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| 0999 | In vivo MR elastography of the murine hippocampus is sensitive to the microscopic mechanical properties of dentate gyrus subzones | |
| Anna Morr1, Marcin Nowicki2, Gergely Bertalan1, Rafaela Vieira da Silva1, Carmen Infante Duarte1, Stefan Paul Koch1, Philipp Boehm-Sturm1, Ute Krügel2, Jürgen Braun1, Barbara Steiner1, Josef Käs2, Thomas Fuhs2, and Ingolf Sack1 | ||
1Charité - Universitätsmedizin Berlin, Berlin, Germany, 2Universität Leipzig, Leipzig, Germany |
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In this study, we investigated the mechanical properties of subregions of the murine dentate gyrus in vivo using MR elastography (MRE) and ex vivo with atomic force microscopy (AFM). Consistent with AFM, subregional analysis of the dentate gyrus by MRE revealed that the subgranular zone (SGZ), in which adult neurogenesis takes place, is characterized by marked soft-solid properties. We conclude that MRE is sensitive to micromechanical properties beyond the image resolution. The observed soft-solid material properties of the SGZ quantified by AFM and MRE might be of functional relevance for neurogenesis in the mouse brain. |
| 1000 | Are multiple sclerosis lesions stiffer or softer than surrounding brain tissue? | |
| Helge Herthum1, Stefan Hetzer2, Michael Scheel1, Friedemann Paul3, Heiko Tzschätzsch1, Tom Meyer1, Mehrgan Shahryari1, Jürgen Braun4, and Ingolf Sack1 | ||
1Experimentelle Radiologie, Charité Universitätsmedizin Berlin, Berlin, Germany, 2Berlin Center for Advanced Neuroimaging (BCAN), Berlin, Germany, 3NeuroCure Clinical Research Center and Clinical and Experimental Multiple Sclerosis Research Center, Berlin, Germany, 4Institut für medizinische Informatik, Charité Universitätsmedizin Berlin, Berlin, Germany |
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Using multifrequency MR elastography with 2- and 1.5mm resolutions in a cohort of 19 patients with multiple sclerosis and a total 206 analyzed lesions we found no evidence for systematic differences in the viscoelastic properties between MS lesions and surrounding brain tissue. Although future technical improvements in MRE resolution and parameter reconstruction methods might reveal significant differences between lesion and brain properties, our results indicate that those differences are minor compared to other published changes in brain viscoelasticity of the human brain. |
| 1001 | Brain MR-Elastography in microgravity analogous conditions | |
| Fatiha Andoh1, Claire Pellot-Barakat1, and Xavier Maître1 | ||
1Université Paris-Saclay, CEA, CNRS, Inserm, BioMaps, Orsay, France |
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The head down tilt (HDT) position is commonly used to simulate vascular and tissue fluid dynamics during spaceflights. In HDT position, the cerebral autoregulation faces difficulties to adjust the vascular tone while the cephalad fluid shifts may yield increased intracranial pressures and altered mechanical properties. MRI T2 mapping in HDT position have shown fluid overpressure in the brain and resulting loss of water contents in the CSF and orbital compartments. Whole brain MRE was performed here in similar HDT conditions. It was sensitive enough to provide new insights on the overall mechanical response of brain tissues in microgravity analogous conditions. |
| 1002 | Micro MR elastography of the zebrafish brain | |
| Jakob Jordan1, Gergely Bertalan1, Heiko Tzschätzsch1, Tom Meyer1, Anton Gauert2, Anja Heeren-Hagemann2, Jürgen Braun3, and Ingolf Sack1 | ||
1Department of Radiology, Charité - Universitätsmedizin Berlin, Berlin, Germany, 2Department of Hematology/Oncology, Charité - Universitätsmedizin Berlin, Berlin, Germany, 3Institute of Medical Informatic, Charité - Universitätsmedizin Berlin, Berlin, Germany |
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Zebrafish have emerged as a versatile, cost-efficient and easy-to-handle animal model in many areas of biomedical research. Using multifrequency MR elastography at 7-Tesla and 1000 to 1400 Hz excitation frequency, we analyzed the viscoelastic properties of the post-mortem zebrafish brain. Shear wave speed as a surrogate marker of stiffness was mapped with an in-plane resolution of 40 microns showing stiffer properties (1.2±0.3 m/s) of the brain than skeletal muscle (0.89±0.09 m/s). Furthermore, sub-regions showed distinct stiffness properties, which, however, lacked significance in this preliminary feasibility study. |
| 1003 | Heterogeneity of Viscoelastic Properties in Prostate Cancer Assessed by Ex Vivo MR Elastography | |
| Rolf Reiter1,2, Shreyan Majumdar2, Steven Kearney2, Andre Kajdacsy‐Balla3, Virgilia Macias3, Michael Abern4, Simone Crivellaro4, Thomas J. Royston2, and Dieter Klatt2 | ||
1Radiology, Charité - Universitätsmedizin Berlin, Berlin, Germany, 2Bioengineering, University of Illinois at Chicago, Chicago, IL, United States, 3Pathology, University of Illinois at Chicago, Chicago, IL, United States, 4Urology, University of Illinois at Chicago, Chicago, IL, United States |
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We aimed to evaluate the heterogeneity of viscoelastic tissue properties of fresh prostatectomy specimens of men with prostate cancer using MR elastography and histopathology as a reference. Our results suggest that prostate cancer is characterized by a stiff yet homogeneous biomechanical signature. A possible explanation for this finding might be differences of healthy vs. cancerous tissue based on anatomical zones and their specific nonmalignant pathologies (prostatitis in the peripheral zone and benign prostatic hyperplasia in the central gland), and the unique nondestructive growth pattern of PC with intervening stroma which might provide a rigid scaffold. |
| 1004 | MR elastography of abdominal aortic aneurysm specimens | |
| Dilyana B. Mangarova1,2, Julia Brangsch1, Marcus R. Makowski1,3, Bernd Hamm1, Ingolf Sack1, Jürgen Braun 4, and Gergely Bertalan1 | ||
1Department of Radiology, Charité - Universitätsmedizin Berlin, Berlin, Germany, 2Department of Veterinary Pathology, Free University of Berlin, Berlin, Germany, 3Department of Diagnostic and Interventional Radiology, Technical University of Munich, Berlin, Germany, 4Institute for Medical Informatics, Charité - Universitätsmedizin Berlin, Berlin, Germany |
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Abdominal aortic aneurysms (AAA) are among the worldwide leading causes of death. Standard MRI and ultrasonography cannot predict the risk of life-threatening AAA rupture. The ECM composition and therefore the stiffness of the aortic wall changes during AAA development and progression. Therefore, we investigated AAA stiffness in murine tissue samples using MR elastography with an in-plane resolution of 40 microns. Compared to healthy aorta, we found an increase of vessel wall stiffness in AAA of approximately 20% and an excellent correlation of histology-quantified ECM accumulation with thrombus stiffness. |
| 1005 | Viscoelastic Differences in Human Gray and White Matter at Different Spatial Resolutions | |
| Shruti Mishra1,2, Bin Deng2,3,4, W. Scott Hoge1,2,3, Giacomo Annio5, Ralph Sinkus5, and Samuel Patz1,2 | ||
1Department of Radiology, Brigham & Women's Hospital, Boston, MA, United States, 2Harvard Medical School, Boston, MA, United States, 3Athinoula A. Marginos Center for Biomedical Imaging, Charlestown, MA, United States, 4Radiology, Massachusetts General Hospital, Boston, MA, United States, 5Laboratory for Vascular Translational Science (LVTS), Institut National de la Santé et de la Recherche Médicale (INSERM), Paris, France |
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Magnetic resonance elastography (MRE) was utilized to demonstrate differences in shear wavelength between human cortical gray matter and subcortical white matter and evaluate the effect of spatial resolution on wavelength estimation. Much greater brain architectural detail was discerned in the viscoelastic maps when going from 2.5 mm to 1.5 mm isotropic spatial resolution. We also demonstrate in individual healthy subjects, through two adjacent multi-voxel regions of interest, that cortical gray matter is stiffer than adjacent subcortical white matter, and that this difference is accentuated at higher resolutions. Furthermore, we show that the mean estimated wavelength increases with decreasing spatial resolution. |
| 1006 | Assessment of Obesity-Related Inflammation in Subcutaneous Adipose Tissue with MR Elastography (MRE) | |
| Jiahui Li1, Prachi Singh2, Marzanna Obrzut1, Xin Lu1, Kevin J. Glaser1, Alina Allen3, Sudhakar K. Venkatesh1, Taofic Mounajjed4, Jun Chen1, Armando Manduca1, Vijay Shah3, Richard L. Ehman1, and Meng Yin1 | ||
1Radiology, Mayo Clinic, Rochester, MN, United States, 2Sleep and Cardiometabolic Health, Pennington Biomedical Research Center, Baton Rouge, LA, United States, 3Gastroenterology, Mayo Clinic, Rochester, MN, United States, 4Anatomic Pathology, Mayo Clinic, Rochester, MN, United States |
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Multiparametric MRI and MRE was performed in 27 obese patients who had biopsies of liver and subcutaneous adipose tissues. We found significant correlations between the mechanical properties of liver and subcutaneous fat and their histological and biochemistry results. A model combining liver proton density fat fraction and subcutaneous fat stiffness had a slightly higher AUC for diagnosing nonalcoholic steatohepatitis than liver stiffness (AUC: 0.87 vs. 0.84, p=0.74). The results indicate that obesity-induced systemic inflammation affects both adipose and liver tissue mechanical properties and, therefore, models utilizing mechanical biomarkers from adipose tissue may improve the diagnosis of steatohepatitis in obese patients. |
| 1007 | Anisotropic stiffness of the supraspinatus muscle estimated via MR elastography and transversely isotropic nonlinear inversion. | |
| Elijah Van Houten1, Cyril Tous2,3, Alexandre Jodoin4, Matthew McGarry5, Philip Bayly6, Keith Paulsen5,7, Curtis Johnson8, and Nathalie Bureau2,4 | ||
1Mechanical Engineering, Université de Sherbroke, Sherbrooke, QC, Canada, 2Centre de recherche du Centre hospitalier de l’Université de Montréal, Montréal, QC, Canada, 3Université de Montréal, Montréal, QC, Canada, 4Department of Radiology, Centre hospitalier de l’Université de Montréal, Montréal, QC, Canada, 5Thayer School of Engineering, Dartmouth College, Hanover, NH, United States, 6Department of Mechanical Engineering & Materials Science, Washington University in St. Louis, St. Louis, MO, United States, 7Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States, 8Department of Biomedical Engineering, University of Delaware, Newark, DE, United States |
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Surgical planning for rotator cuff repair would benefit significantly from quantitative measures of the muscle stiffness to avoid re-tearing of the muscle after surgery. MR Elastography (MRE) can provide quantitative measures of soft tissue stiffness in-vivo, but repeatable, stable results require accurate tissue models capable of treating the specific geometry and highly anisotropic structure of muscle tissue. Here, MRE based on a nearly incompressible, transversely isotropic continuum model is developed and applied to the case of the supraspinatus muscle. Overall, results show good agreement between reconstructed anisotropic stiffness values and independently published results based on wavelength analysis. |
| 1008 | Assessment of Shear Strain in Intervertebral Discs In Vivo with Magnetic Resonance Elastography | |
| Yuan Le1, Jun Chen1, Phillip J. Rossman1, Ziying Yin1, Kevin J. Glaser1, Joshua D. Trzasko1, Yi Sui1, Stephan Kannengiesser2, Bradley D. Bolster, Jr.3, Joel P. Felmlee1, and Richard L. Ehman1 | ||
1Radiology, Mayo Clinic, Rochester, MN, United States, 2Siemens Healthcare GmbH, Erlangen, Germany, 3Siemens Medical Solutions USA, Inc., Salt Lake City, UT, United States |
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This study is to test the feasibility of visualizing waves propagating in the spine and measuring the strain in the intervertebral discs (IVDs) in vivo with Magnetic Resonance Elastography (MRE). Our results show that waves can be visualized, and that IVD shear strain can be quantitatively assessed. Degeneration of the IVD is thought to decrease disc shear stiffness. Preliminary results in a series of volunteers demonstrated increasing IVD shear strain with age, consistent with the known gradual degradation of IVD function with age. |
| 1009 | 3D-MRE as independent predictor of direct portal venous pressure compared to Biopsy derived Fibrosis Measurements | |
| Giacomo Annio1,2, Ahmed Hamimi3, Khaled Z. Abd-Elmoniem 3, Theo Heller3, Elliot Levy 3, David E. Kleiner4, Ohad Etzion5, Rabab Ali6, Ralph Sinkus1,2, and Ahmed M. Gharib3 | ||
1LVTS, INSERM U1148, Paris, France, 2Department of Biomedical Engineering, King's College London, London, United Kingdom, 3Biomedical and Metabolic Imaging Branch, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD, United States, 4Center for Cancer Research, National Cancer Institute, Bethesda, MD, United States, 5Department of Gastroenterology and Liver Diseases, Ben-Gurion University of the Negev, Be'er Sheva, Israel, 6Department of Internal Medicine, Duke University, Durham, NC, United States |
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The assessment of liver fibrosis and inflammation is crucial to the clinical management of patients suffering from liver diseases. Portal venous pressure assessment has important prognostic implications for hepatic disease patients’ care. However, it can only be measured invasively. In this work we show that liver stiffness quantified via 3DMRE is a strong independent predictor of DPVP compared to invasive biopsy. Moreover stiffness as evaluated with 3DMRE is an operator independent and non-invasive biomarker which could hence constitute an optimal method for diagnosis and fibrosis staging in all patients and a non-invasive surrogate of DPVP. |
| 1010 | Estimating Aortic Stiffness Using Aortic MR Elastography Using an Inversion without Considering the Geometry | |
| Huiming Dong1, Prateek Kalra1, Richard D White1, and Arunark Kolipaka1 | ||
1Radiology, The Ohio State University Wexner Medical Center, Columbus, OH, United States |
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Aortic stiffness is a valuable imaging marker because of its association with a variety of cardiovascular conditions such as abdominal aortic aneurysm (AAA). Calculating AAA stiffness from aortic MRE data presents a unique challenge due to the relatively small size of an AAA compared to the liver. In the present study, we propose a new inversion strategy that consists of directional filters that are designed to extract the propagating waves along the axial direction of the AAA, and uses the wave information along the axial direction for stiffness calculation to reduce the impact of AAA geometry on stiffness estimation. |
| 1011 | Preliminary MR elastography investigation on HIV+ cohort with cerebral small vessel disease | |
| Abrar Faiyaz1, Irteza Enan Kabir1, Marvin M Doyley1, Ingolf Sack2, Md Nasir Uddin3, and Giovanni Schifitto3 | ||
1Department of ECE, University of Rochester, Rochester, NY, United States, 2Department of Radiology, Charité - Universitätsmedizin Berlin, Berlin, Germany, 3Department of Neurology, University of Rochester, Rochester, NY, United States |
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Neuroinflammation plays a crucial role in HIV-infected subjects at risk of cerebral small vessel disease. As MR-Elastography (MRE) has shown the potential to link inflammation with brain stiffness reduction, we investigated the brain viscoelastic properties of the HIV-infected and HIV-uninfected individuals. The preliminary results with MRE are promising, complementing other imaging modalities such as diffusion MRI (DTI, NODDI) to investigate brain microstructure integrity in HIV infection. |
| 1012 | A Learned Phase Correction Algorithm Outperforms a Conventional Filter for 3D Vector MRE | |
| Jonathan M Trevathan1, Jonathan M Scott1, Joshua D Trzasko1, Armando Manduca1, John Huston1, Richard L Ehman1, and Matthew C Murphy1 | ||
1Mayo Clinic, Rochester, MN, United States |
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Bulk motion during the motion encoding of multi-slice spin-echo EPI pulse sequences used to acquire 3D MRE data creates a slice-to-slice phase jitter. A 3D convolutional neural network was trained to estimate a phasor corresponding to noise-free displacements given noisy, complex-valued MRE data. The net outperformed its filtering counterpart in noisy and noise-free simulation data, and decreased test-retest repeatability error in vivo. |
| 1013 | MR Elastography Reconstruction Based on a Linear Integral Equation Derived from the Helmholtz Identity | |
| Motofumi Fushimi1, Naohiro Eda1, and Takaaki Nara1 | ||
1The University of Tokyo, Tokyo, Japan |
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This paper presents a novel reconstruction method for MR Elastography. Unlike most conventional methods that solve Navier's partial differential equation (PDE), the proposed approach solves a linear integral equation derived from Helmholtz’s identity. The proposed method can reconstruct the complex shear modulus without calculating higher-order derivatives of the measured displacement data, nor solving a nonlinear minimization problem that could result in local minima. Our preliminary study by numerical simulations demonstrated that the proposed method could robustly estimate the complex shear modulus. Future work is to compare the effectiveness of the proposed method with the PDE-based conventional methods. |
| 1014 | Viscoelastic MRE Phantoms with Tunable Damping Ratio Independent of Shear Stiffness | |
| L. Tyler Williams1, Zheng Cao1, Matthew D. J. McGarry2, Elise A. Corbin1, and Curtis L. Johnson1 | ||
1Biomedical Engineering, University of Delaware, Newark, DE, United States, 2Thayer School of Engineering, Dartmouth College, Hanover, NH, United States |
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This study validates the use of LPAA/PAA gels as viscoelastic MRE phantoms with tunable damping ratio independent of shear stiffness. PAA concentration was 6wt% across all phantoms while LPAA concentration ranged from 0 to 6wt%. High-resolution MRE scans were conducted with 600, 700, 800, and 900 Hz vibrations. For each frequency, storage modulus and shear stiffness were constant while loss modulus and damping ratio increased with increasing LPAA concentration. For each LPAA concentration, loss modulus increased with increasing frequency indicating viscoelastic behavior. These results verify the independent tunability of damping ratio and shear stiffness. |
| 1015 | Investigation of Motion as a Source of Error in MR Elastography | |
| Emily Chan1, Daniel Fovargue1, Matt Kelly2, Ralph Sinkus1,3, and Julia A Schnabel1 | ||
1School of Biomedical Engineering & Imaging Sciences, King's College London, London, United Kingdom, 2Perspectum, Oxford, United Kingdom, 3INSERM U1148, Laboratory for Vascular Translational Science, University Paris Diderot, University Paris 13, Paris, France |
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Clinically, motion occurring between breath-hold acquisitions during a magnetic resonance elastography (MRE) scan is assumed negligible and therefore not corrected. In this work, we demonstrate through simulations on a phantom that motion of this degree does impact elasticity reconstruction, which highlights the need for care to be taken to account for this motion. |
| 1016 | A viscoelastic phantom of the healthy human liver for elastography in MRI and ultrasound | |
| Anna Morr1, Helge Herthum1, Felix Schrank1, Steffen Görner1, Jürgen Braun1, Ingolf Sack1, and Heiko Tzschätzsch1 | ||
1Charité - Universitätsmedizin Berlin, Berlin, Germany |
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Elastography in MRI (MRE) and ultrasound (USE) are the most reliable imaging techniques for liver fibrosis detection. However, there is no established, standardized material that mimics the elasticity and viscous behavior of liver tissue and can be used as a phantom for MRE and USE. We developed a phantom based on polyacrylamide which shows a viscoelastic dispersion from 5-3000 Hz similar to that observed in the healthy human liver, which is measurable by MRE and USE, stable over months and can be produced in a reproducible way. The novel phantom facilitates technical improvements and cross-modality comparisons in MRE and USE. |
| 1017 | Simultaneous acquisition for magnetic resonance elastography and fat quantification of the liver | |
| Shuo Li1, Suhao Qiu1, Chenfei Shen1, Yuan Feng1, and Yiping P. Du1 | ||
1School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China |
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Magnetic resonance elastography (MRE) has been used for tumor detection and liver fibrosis evaluation. The existence of intratumoral fat suggests a lower risk of microvascular invasion of combined hepatocellular-cholangiocarcinoma. The combination of MRE and fat quantification can provide sufficient sensitivity to detect substantial macrovesicular hepatic steatosis or fibrosis. In clinical practice, MRE and fat quantification are scanned separately. However, this may cause slice mis-registration between MRE and fat quantification, and increase scan time. In this study, the feasibility of simultaneous acquisition for MRE and fat quantification was demonstrated. This technique can have several potential clinical applications without increasing scan time. |
| 1018 | Effect of different driver power amplitudes on the measurement of liver stiffness in pediatric liver MR elastography | |
| Dong Kyu Kim1, Kyunghwa Han2, Haesung Yoon3, Mi-Jung Lee3, and Hyun Joo Shin3 | ||
1Radiology, Armed Forces Capital Hospital, Seongnam, Korea, Republic of, 2Center for Clinical Imaging Data Science, Severance Hospital, Seoul, Korea, Republic of, 3Radiology, Severance Hospital, Seoul, Korea, Republic of |
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The standard driver power of magnetic resonance elastography (MRE) in pediatric patients is recommended to be reduced by 20–50%, compared to adult patients, to keep the patients from any injury due to the vibrating driver, however, there is limited published information on driver power of MRE in pediatric applications. Furthermore, there is lack of study to evaluate whether different amplitudes of driver power may affect the measurement of liver stiffness on pediatric MRE. In this abstract, we assessed the effect of different driver power amplitudes on the measurement of liver stiffness in pediatric liver MRE. |
| 1019 | Optimal multiple motion encoding in phase contrast MRI | |
| Helge Herthum1, Hugo Carrillo2, Axel Osses2, Sergio Uribe3, Ingolf Sack1, and Cristóbal Bertoglio4 | ||
1Experimentelle Radiologie, Charité Universitätsmedizin Berlin, Berlin, Germany, 2Center for Mathematical Modeling, Universidad de Chile, Santiago, Chile, 3Department of Radiology, School of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile, 4Bernoulli Institute, University of Groningen, Groningen, Netherlands |
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Optimal multiple motion encoding (OMME) for phase-contrast MRI was developed with application to magnetic resonance elastography for unwrapping motion images. OMME is formulated as a least-squares problem using multiple phase-contrast measurements with different motion encoding gradients (MEG). OMME is applied to phantom and in vivo human brain experiments. The wrap-free motion images are further used to reconstruct shear-wave-speed maps and compared to conventional phase unwrapping methods. OMME generates wrap free phase-contrast images with the wrap limit determined by the smallest MEG used, while maintaining the signal-to-noise ratio(SNR) of the largest MEG, which makes OMME especially suitable for high SNR applications. |
| 1020 | In Silico Evaluation of Magnetic Resonance Elastography of the Kidney | |
| Deirdre McGrath1, Christopher Bradley1, and Susan Francis1 | ||
1Sir Peter Mansfield Imaging Centre, University of Nottingham, Nottingham, United Kingdom |
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The accuracy of clinical magnetic resonance elastography (MRE) is difficult to determine. Finite element modelling (FEM) simulation allows evaluation of the errors on acquired MRE measures, and also informs methodological optimisation. In this study kidney MRE is simulated using an anthropomorphic personalised model of the kidneys, and simulated data is compared with a 2D GRE MRE acquisition of the same volunteer on whom the model was based. The optimum MRE imaging resolution was identified, and through adding simulated noise to the FEM data, errors were estimated for the acquired MRE data, and recommendations made for kidney MRE optimisation. |
| 1021 | Optimization of GRE-MRE in the pancreas | |
| Anne-Sophie van Schelt1, Nienke Wassenaar1, Eric M Schrauben1, Marian Troelstra1,2, Jules L. Nelissen1, Ralph Sinkus2,3, Jaap Stoker4, Aart J Nederveen1, and Jurgen H Runge1 | ||
1Radiology and Nuclear Medicine, Amsterdam UMC location AMC, Amsterdam, Netherlands, 2Department of Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom, 3Inserm U1148, LVTS, University Paris Diderot, Paris, France, 4Radiology and Nuclear medicine, Amsterdam UMC location AMC, Amsterdam, Netherlands |
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Pancreatic Magnetic Resonance Elastography (MRE) allows non-invasive estimation of pancreatic tissue visco-elastic properties for multiple pathophysiological diseases. The aim of this study is to optimize pancreatic GRE-MRE to provide an in-depth analysis of the propagation and registration of shear waves. Optimization was performed using four combinations of frequency, the number of measured wave-phase offsets, and TE. Pancreas GRE-MRE at 40Hz, TE 6.9ms and 4 or 5 wave-phase offsets can estimate the SWS of the pancreas head with optimal encoding and propagation and has an acceptable breath-hold duration for clinical purposes. |
| 1022 | An Electromagnetic Actuator for Brain Magnetic Resonance Elastography | |
| Suhao Qiu1, Zhao He1, Runke Wang1, Ruokun Li2, Fuhua Yan2, and Yuan Feng1 | ||
1the Institute for Medical Imaging Technology, Shanghai Jiao Tong University, Shanghai, China, 2the Department of Radiology, Ruijin Hospital, Shanghai, China |
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Effective actuators are crucial for brain magnetic resonance elastography (MRE). In this study, we designed, tested, and verified an electromagnetic actuator. With a grappler-shaped design, the actuator was easy to use and comfortable to wear on head. Phantom and brain experiments indicated that the proposed actuator did not interference with routine imaging sequences. It generated stable shear waves with a full width at half maximum of 0.3 Hz in the frequency spectrum. Phantom and brain MRE demonstrated that the actuator could carry out multi-frequency MRE with a high frequency accuracy. |
| 1023 | Magnetic resonance elastography of the in vivo human brain using multifrequency wavenumber analysis in 2D and 3D. | |
| Helge Herthum1, Heiko Tzschätzsch1, Tom Meyer1, Mehrgan Shahryari1, Lisa Stencel1, Jing Guo1, Jürgen Braun2, and Ingolf Sack1 | ||
1Experimentelle Radiologie, Charité Universitätsmedizin Berlin, Berlin, Germany, 2Institut für medizinische Informatik, Charité Universitätsmedizin Berlin, Berlin, Germany |
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Wavenumber analyses in MR elastography (MRE), which use first-order finite difference operators, are known to be more stable against noise than second-order finite derivative methods. However, wavenumber analyses for the human brain normally suffer from abundant heterogeneities and solid-fluid interfaces. We here present multifrequency wavenumber analysis for MRE of the human brain in 2D and 3D based on adapted bandpass filters. We show that both approaches provide better repeatability in test-retest experiments compared to standard analyses. Moreover, wavenumber analyses yield stable values and rich detail in regions of lower signal-to-noise-ratio such as deep gray matter. |
| 1024 | Deep Learning Automation for Human Brain Masking of Multi-Band MR Elastography | |
| Aaron Thomas Anderson1,2, Siddharth Muralidaran3, Alexander M Cerjanic1,4, Bradley P Sutton1,4, Mark A Anastasio1,4, and Frank J Brooks1,4 | ||
1Beckman Institute for Advanced Science & Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States, 2Stephens Family Clinical Research Institute, Carle Foundation Hospital, Urbana, IL, United States, 3Electrical & Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, United States, 4Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL, United States |
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The processing steps involved in MR elastography include custom imaging sequences, image reconstruction, and material property estimation, but the most person-hours are spent on manual image masking. Manual corrections are needed because automated brain segmentation often fails near temporal lobe artifacts, which are unique for each subject. A deep learning method, specifically, a U-net architecture, is trained to map input MRE-image intensity data to corresponding manually corrected masks (N=44) with the goal of automating the masking of future MRE brain datasets. We observed the U-net-based masking maintained data quality (OSS-SNR) for all subjects. |
| 1025 | Effect of Spatial Inhomogeneity Models on Performance of Machine Learning Based Inversion Algorithms for Brain Magnetic Resonance Elastography | |
| Jonathan M Scott1, Joshua D Trzasko1, Armando Manduca1, Matthew L Senjem1, Clifford R Jack1, John Huston III1, Richard L Ehman1, and Matthew C Murphy1 | ||
1Mayo Clinic, Rochester, MN, United States |
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Four machine learning inversion algorithms with different material spatial property assumptions (trained on simulated data with homogeneous, piecewise constant, smooth, or piecewise smoothly varying material properties) were evaluated in a brain simulating phantom with stiff inclusions, a test-retest repeatability dataset, and an Alzheimer’s disease dataset. The piecewise smooth inversion produced the highest contrast to noise ratio and allowed the best visualization of inclusions in the phantom study. All four inversions produced stiffness estimates that were repeatable and sensitive to stiffness changes in Alzheimer’s disease. |
| 1026 | Cerebral inversion recovery MR elastography for cortical stiffness quantification | |
| Ledia Lilaj1, Helge Herthum2, Tom Meyer2, Mehrgan Shahryari2, Gergely Bertalan2, Alfonso Caiazzo2, Jürgen Braun3, Thomas Fischer2, Sebastian Hirsch4,5, and Ingolf Sack2 | ||
1Radiology, Charité – Universitätsmedizin Berlin, Berlin, Germany, 2Charité – Universitätsmedizin Berlin, Berlin, Germany, 3Institute of Medical Informatics, Charité – Universitätsmedizin Berlin, Berlin, Germany, 4Berlin Center for Advanced Neuroimaging, Charité – Universitätsmedizin Berlin, Berlin, Germany, 5Bernstein Center for Computational Neuroscience, Berlin, Germany |
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Inversion recovery magnetic resonance elastography (IR-MRE) is a new acquisition technique that performs MRE while selectively nulling the signal generated by one compartment with a specific T1. In phantom and in vivo experiments, free fluid, water or cerebrospinal fluid, was nulled. The shear wave speed (SWS) maps showed no overall change in average values. However, in cortical areas, IR-MRE revealed cortical SWS values 10% higher than in standard MRE, resulting in sharper tissue-CSF interfaces. Besides, ventricles are 39% narrower in IR-MRE than in MRE. In conclusion, IR-MRE allows a more precise quantification of cortical stiffness. |
| 1027 | Multi-Excitation Actuator Design for Anisotropic Brain MRE | |
| Diego A. Caban-Rivera1, Daniel R. Smith1, Keshav A. Kailash2, Ruth J. Okamoto2, Matthew D.J. McGarry 3, Lance T. Williams1, Charlotte Guertler2, Grace Mcilvain1, Damian Sowinski3, Elijah E.W. Van Houten 4, Keith D. Paulsen3,5, Philip V. Bayly2, and Curtis L. Johnson1 | ||
1Biomedical Engineering, University of Delaware, Newark, DE, United States, 2Mechanical Engineering and Material Science, Washington University in St. Louis, St. Louis, MO, United States, 3Thayer School of Engineering, Dartmouth College, Hanover, NH, United States, 4Mechanical Engineering, Université de Sherbrooke, Sherbrooke, QC, Canada, 5Dartmouth-Hitchcock Medical Center, Lebanon, NH, United States |
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The goal of this study is to thoroughly examine a novel customized multi-excitation MRE actuator combining both left-right (LR) and anterior-posterior (AP) drivers for use in estimating anisotropic mechanical properties of the brain. We demonstrate the key differences in wave patterns and how these lead to distinct stiffness estimations. The displacement fields from both excitations were combined to recover repeatable anisotropic properties in the corticospinal tract. The improved ME-MRE actuator can be used for future studies of white matter mechanical properties in health and disease. |
| 1028 | Intra-patient comparison of 3D and 2D MRE techniques for assessment of liver fibrosis | |
| Roberta Catania1, Amir A. Borhani1, Camila Lopes Vendrami1, Roger C Grimm2, Bradley D. Bolster3, and Frank Miller1 | ||
1Northwestern University Feinberg School of Medicine, Chicago, IL, United States, 2Mayo Clinic, Rochester, MN, United States, 3Siemens Medical Solutions USA, Inc., Salt Lake City, UT, United States |
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3D MRE allows volumetric assessment of liver stiffness. Performance of this method as compared to 2D techniques (GRE and seEPI), was evaluated, with respect to the ROI areas per slice, stiffness values, and presence of artifacts. The 3D MRE provided larger area of liver and was less prone to artifacts. Liver Stiffness Measures (LSM) based on 3D technique were lower than 2D technique. 3D MRE exhibits less susceptibility to artifacts and provides larger measurable areas of liver. LSM based on 3D MRE however were lower than 2D techniques. |
| 1029 | Short echo time dual-frequency MR Elastography with Optimal Control RF pulses | |
| Pilar Sango Solanas1, Kevin Tse Ve Koon1, Eric Van Reeth1,2, Cyrielle Caussy3,4, and Olivier Beuf1 | ||
1Univ Lyon, INSA‐Lyon, Université Claude Bernard Lyon 1, UJM-Saint Etienne, CNRS, Inserm, CREATIS UMR 5220, U1206, F‐69616, Lyon, France, 2CPE Lyon, Département Sciences du Numérique, Lyon, France, 3Univ Lyon, Laboratoire CarMen, Inserm, INRAe, INSA Lyon, Université Claude Bernard Lyon 1, Pierre-Bénite, France, 4Hospices Civils de Lyon, Département Endocrinologie, Diabète et Nutrition, Hôpital Lyon Sud, Pierre-Bénite, France |
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Magnetic Resonance Elastography (MRE) quantifies the mechanical properties of tissues, typically applying motion encoding gradients (MEG). High frequencies are difficult to reach due to slew rate limitations and low frequencies induce too long TEs, yielding magnitude images with low SNR. Multifrequency results allow better characterizations of tissues using data usually acquired through sequential monofrequency experiments. In this study, we generate optimal control-based RF pulses to outperform simultaneous multifrequency MRE. The pulse is applied with a constant gradient during the mechanical excitation to simultaneously achieve spatially selective excitation and motion encoding. Results on phantom demonstrated the feasibility of the proposed method. |
| 1030 | Comparative analysis of indentation and magnetic resonance elastography for measuring viscoelastic properties | |
| Yu Chen1, Suhao Qiu1, Zhao He1, Fuhua Yan2, Ruokun Li2, and Yuan Feng1 | ||
1Institute for Medical Imaging Technology, School of Biomedical Engineering, Shanghai Jiao Tog University, Shanghai, China, 2Department of Radiology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China |
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Comparing viscoelastic properties of soft tissues measured in vivo and ex vivo are of interests for basic science and clinical translation. Magnetic resonance elastography (MRE) and indentation are two commonly used techniques for measurement of tissue viscoelasticity. In this study, we used a gelatin phantom to compare measurements by MRE and indentation. Using 2nd-order Prony series, frequency response measured from indentation was estimated. We observed apparent frequency-dependent behaviors from MRE in the range of 50-100 Hz, but not from indentation. Results implied that MRE and indentation measures at different frequency ranges. |
| 1031 | Development of robust MRE for measurement of high-speed functionally mediated changes in human brain viscoelasticity | |
| Bin Deng1,2,3, W. Scott Hoge3,4, Shruti Mishra3,4, Giacomo Annio5, Ralph Sinkus5, and Samuel Patz3,4 | ||
1Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States, 2Radiology, Massachusetts General Hospital, Boston, MA, United States, 3Harvard Medical School, Boston, MA, United States, 4Radiology, Brigham and Women’s Hospital, Boston, MA, United States, 55. Laboratory for Vascular Translational Science (LVTS, Institut National de la Santé et de la Recherche Médicale (INSERM), Paris, France |
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Our aim is to develop a robust, high-spatial resolution and highly reproducible MRE methodology for the measurement of rapid functionally mediated changes in human brain viscoelasticity. Based on prior work in mice, we expect to observe changes in shear wavelength of ~2mm due to functional activation. Using a modified Ristretto fMRE pulse sequence to acquire control data in healthy volunteers, we evaluated the reproducibility of MRE measurements at 2.5-, 2- and 1.5-mm isotropic spatial resolution. Excellent intra-scan consistency was observed between two interleaved paradigm acquisitions at all resolutions with comparable data quality. Robust inter-scan repeatability was also observed. |
| 1032 | Anisotropic Mechanical Properties of White Matter Tracts Estimated with Multi-Excitation MRE and TI-NLI | |
| Daniel R. Smith1, Diego A. Caban-Rivera1, Matthew D. J. McGarry2, L. Tyler Williams1, Grace McIlvain1, Charlotte Guertler3, Ruth J. Okamoto3, Damian Sowinski2, Elijah Van Houten4, Phil V. Bayly3, Keith D. Paulsen2, and Curtis L. Johnson1 | ||
1Biomedical Engineering, University of Delaware, Newark, DE, United States, 2Thayer School of Engineering, Dartmouth College, Hanover, NH, United States, 3Mechanical Engineering and Materials Science, Washington University in St. Lous, St. Louis, MO, United States, 4Mechanical Engineering, Universite de Sherbrooke, Sherbrooke, QC, Canada |
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In this study, we used multi-excitation MR elastography (MRE) in conjunction with transversely isotropic NLI (TI-NLI) to estimate the anisotropic viscoelastic parameters of the human brain. We collected data on ten subjects and took averages of the parameters within individual regions of the brain. Through comparison of regions of interest, we found significant differences between the parameter estimate of gray matter and white matter and between individual white matter tracts. The results of this study indicate that multi-excitation MRE and TI-NLI can generate consistent anisotropic parameter estimates for WM that capture innate differences in individual tract structure. |
| 1232
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Quantitative myelin-sensitive MRIs exhibit differential sensitivity to multiple sclerosis pathology in distinct brain lesions and regions | |
| Reza Rahmanzadeh1,2,3, Po-Jui Lu1,2,3, Muhamed Barakovic1,2,3, Matthias Weigel1,2,3, Laura Gaetano4, Riccardo Galbusera1,2,3, Thanh D. Nguyen5, Francesco La Rosa 6,7, Daniel S. Reich8, Pascal Sati8,9, Yi Wang5, Meritxell Bach Cuadra6,7, Ernst-Wilhelm Radue1,2, Jens Kuhle1,3, Ludwig Kappos1,3, Stefano Magon10, and Cristina Granziera1,2,3 | ||
1Neurologic Clinic and Policlinic, Departments of Medicine, Clinical Research and Biomedical Engineering, University Hospital Basel and University of Basel, Basel, Switzerland, 2Translational Imaging in Neurology (ThINk) Basel, Department of Biomedical Engineering, University Hospital Basel and University of Basel, Basel, Switzerland, 3Research Center for Clinical Neuroimmunology and Neuroscience (RC2NB) Basel, University Hospital Basel and University of Basel, Basel, Switzerland, 4Hoffmann-La Roche Ltd., Basel, Switzerland, 5Department of Radiology, Weill Cornell Medical College, New York, NY, United States, 6Signal Processing Laboratory (LTS5), Ecole Polytechnique Fédérale de Lausanne (EPFL), Laussane, Switzerland, 7Radiology Department, Center for Biomedical Imaging (CIBM), Lausanne University and University Hospital, Laussane, Switzerland, 8Translational Neuroradiology Section, National Institute of Neurological Disorders and Stroke, NIH, 10 Center Drive MSC 1400, Building 10 Room 5C103, Bethesda, MD, United States, 9Department of Neurology, Cedars-Sinai Medical Center, Los Angeles, CA, United States, 10Pharmaceutical Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd., Basel, Switzerland |
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The differential sensitivity of myelin-sensitive advanced MRIs (aMRIs) to the pathology in various brain lesions and regions in multiple sclerosis (MS) is currently debated. This study aimed to address this issue using myelin water fraction maps (MWF), quantitative susceptibility mapping (QSM) and T1 relaxometry (qT1). Our results show that (i) qT1 is the most sensitive in differentiating white matter and cortical MS lesions from normal-appearing tissue (ii) QSM is best differentiating lesions with various extent of damage (lesions with vs without paramagnetic rim & periventricular vs juxta-cortical lesions) and (iii) MWF outperforms the other aMRI methods in identifying occult normal appearing pathology. |
| 1233 | Three-dimensional whole-brain simultaneous quantitative mapping of T1, T2, T2*, and susceptibility with MR Multitasking | |
| Tianle Cao1,2, Sen Ma1, Nan Wang1, Sara Gharabaghi3, Yibin Xie1, Zhaoyang Fan1,4,5, Elliot Hogg6, E. Mark Haacke 3,7,8, Michele Tagliati6, Anthony G. Christodoulou1,2, and Debiao Li1,2 | ||
1Biomedical Imaging Research Institute, Cedars Sinai Medical Center, Los Angeles, CA, United States, 2Department of Bioengineering, University of California, Los Angeles, Los Angeles, CA, United States, 3Magnetic Resonance Innovations, Inc., Bingham Farms, MI, United States, 4Department of Radiation Oncology, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States, 5Department of Radiology, University of Southern California, Los Angeles, CA, United States, 6Department of Neurology, Cedars Sinai Medical Center, Los Angeles, CA, United States, 7Department of Radiology, Wayne State University School of Medicine, Detroit, MI, United States, 8The MRI Institute for Biomedical Research, Bingham Farms, MI, United States |
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A new approach for simultaneous quantitative mapping of T1, T2, T2*, and susceptibility was developed. This technique employs hybrid T2 preparation/inversion pulse modules followed by fully flow-compensated multi-echo FLASH readouts. Our method reconstructs images with different T2 preparation times, echo times, and inversion times in the MR Multitasking framework and use them for parameter quantification. Results of both visual comparison and statistical analysis showed that our proposed method agreed well with reference methods while being more time efficient. |
| 1234 | 3D Isotropic-resolution Non-rigid Motion Compensated Liver T1, T2 and fat fraction mapping | |
| Giorgia Milotta1, Gastao Cruz2, Radhouene Neji2, Claudia Prieto2, and Rene Botnar2 | ||
1University College London, London, United Kingdom, 2King's College London, London, United Kingdom |
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Quantitative T1 and T2 mapping has shown promising results in the quantification of liver fibrosis and inflammation, whereas proton density fat fraction mapping has been used to quantify the hepatic lipid content in fatty liver diseases. Conventionally multiple sequential 2D breath-held scans are performed to acquire sequential 2D T1, T2 and fat fraction maps. However, this approach suffers from limited spatial resolution and coverage and potential misregistration errors. In this work, we sought to develop a free-breathing non-rigid motion corrected 3D sequence for simultaneous and co-registered acquisition of joint liver T1, T2 and fat fraction maps for quantitative tissue characterization |
| 1235 | Multi-contrast MRI Atlas of the Cynomolgus Macaque Brain | |
| Rakshit Dadarwal1,2 and Susann Boretius1,2 | ||
1Functional Imaging Laboratory, German Primate Center, Göttingen, Germany, 2Georg August Universität Göttingen, Göttingen, Germany |
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Neuroimaging studies require a species-specific template to promote an exquisite spatial normalization. In this work, we provide a high-resolution multi-contrast MRI template of the cynomolgus macaque (Macaca fascicularis) brain. This template may serve as a standard neuroanatomical template to normalize single subject scans in the stereotaxic space. The incorporation of multiple MRI contrast mechanisms provides excellent contrast between gray matter, white matter, and subcortical structures with fine neuroanatomical details. |
| 1236 | Generation of co-registered multi-contrast MR images for carotid atherosclerosis evaluation based on a single SIMPLE sequence | |
| Jiaqi Dou1, Yajie Wang1, Huiyu Qiao1, Zhensen Chen1, Yuze Li1, Haikun Qi2, Jie Sun3, Dongxiang Xu3, Xihai Zhao1, and Huijun Chen1 | ||
1Center for Biomedical Imaging Research, School of Medicine, Tsinghua University, Beijing, China, 2School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom, 3Department of Radiology, University of Washington, Seattle, WA, United States |
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Carotid atherosclerosis is a leading cause of ischemic stroke worldwide. Multi-contrast magnetic resonance imaging (MRI) is an ideal non-invasive technique to assess carotid plaque. However, its clinical application is limited by long scan time and non-rigid registration between different contrasts. In this study, we generated a set of co-registered T1w, T2w, PDw images, and MR angiogram (MRA) in one scan based on the SIMPLE (SImultaneous T1 and T2 Mapping of carotid PLaquE) sequence. Preliminary experiments on patients validated the feasibility of the generated multi-contrast images for carotid plaque assessment and comparable performance with conventional sequences. |
| 1237 | Multiparametric MRI Distinguishes Cerebral Radiation Necrosis vs. Recurrent Glioma in Mouse Models | |
| Xia Ge1, John A Engelbach1, Liya Yuan2, Sonika Dahiya3, Feng Gao4, Keith M Rich2, Joseph JH Ackerman1,5,6,7, and Joel R Garbow1,5 | ||
1Radiology, Washington University in St Louis, St Louis, MO, United States, 2Neurosurgery, Washington University in St Louis, St Louis, MO, United States, 3Neuropathology, Washington University in St Louis, St Louis, MO, United States, 4Surgery, Washington University in St Louis, St Louis, MO, United States, 5Alvin J Siteman Cancer Center, Washington University in St Louis, St Louis, MO, United States, 6Internal Medicine, Washington University in St Louis, St Louis, MO, United States, 7Chemistry Department, Washington University in St Louis, St Louis, MO, United States |
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Malignant brain tumor patients treated with radiation are at risk of developing subsequent treatment effects, including radiation necrosis (RN), which cannot be differentiated from recurrent tumor. We have developed mouse models of RN and of admixed tumor growing in previously irradiated brain (“mixed lesion”) that recapitulate the major histologic characteristics of human RN and recurrent glioma, respectively. These models provide a platform for the development of imaging biomarkers capable of differentiating RN vs. tumor. We demonstrate a multiparametric, clinically translatable 1H MRI pipeline (R1, R1-post-contrast, R2, ADC, MTR, and DCEAUC) that shows significant promise for differentiating RN vs. recurrent tumor. |
| 1238 | Changes of native T1, T1ρ, and T2 values during liver fibrosis in rats at 11.7T MRI | |
| Yimei Lu1, Qianfeng Wang2, and Dengbin Wang1 | ||
1Department of Radiology, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, shanghai, China, 2Fudan University, Institute of Science and Technology for Brain-Inspired Intelligence, shanghai, China |
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The relaxation times (including T1, T2, and T1ρ) are tissue-specific parameters , and depend on the physical, chemical and biological characteristics of the tissue. In liver fibrosis, the deposition of macromolecules (such as collagen fibers, proteoglycans, etc.) in the extracellular matrix may affect the movement of free protons, resulting in tissue relaxation times change. Many studies have shown that native T1 and T2 values are related to the degree of liver fibrosis. We investigate the influence of different pathological changes on T1 mapping, T1ρ, and T2 mapping in two vivo animal models of liver fibrosis, with a focus on liver fibrosis. |
| 1239 | Multi-Physics Multi-Contrast Magnetic Resonance Imaging | |
| Mehdi Sadighi1, Mert Şişman1, and B. Murat Eyüboğlu1 | ||
1Electrical and Electronics Eng., Middle East Technical University (METU), Ankara, Turkey |
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In this study, a Diffusion-Weighted (DW) Spin Echo (SE) based pulse sequence with current injection is proposed to combine data acquisitions of the Diffusion Tensor ($$$\overline{\overline{D}}$$$), current-induced magnetic flux density $$$B_z$$$ and the magnetohydrodynamic (MHD) flow imaging. The current density distribution ($$$\overline{J}$$$) can be estimated from the measured $$$B_z$$$ using the MRCDI method and the conductivity tensor can be reconstructed from the acquired $$$\overline{\overline{D}}$$$ and the estimated $$$\overline{J}$$$ using the DT-MREIT method. The acquired results of an experimental phantom with anisotropic diffusion using DW-SE pulse sequence shows that the proposed method could provide multi-contrast imaging based on multiple physical properties. |
| 1240 | Optimising multi-contrast MRI experiment design using concrete autoencoders | |
| Chantal Tax1,2, Hugo Larochelle3, Joao P. De Almeida Martins4, Jana Hutter5, Derek K. Jones2, Maxime Chamberland2, and Maxime Descoteaux6 | ||
1Image Sciences Institute, University Medical Center Utrecht, Utrecht, Netherlands, 2CUBRIC, Cardiff University, Cardiff, United Kingdom, 3Google Brain, Montreal, QC, Canada, 4Department of Radiology and Nuclear Medicine, St. Olav's University Hospital, Trondheim, Norway, 5Centre for Medical Engineering, King's College London, London, United Kingdom, 6SCIL, University of Sherbrooke, Sherbrooke, QC, Canada |
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Multi-contrast MRI provides a comprehensive picture of tissue microstructure, but the high dimensionality of the parameter space increases scan time. In this work, we present a data-driven approach to multi-contrast MRI experiment design using concrete autoencoders. Concrete autoencoders simultaneously perform measurement subset-selection and learn a prediction of the full set of measurements. This approach was evaluated on two multi-contrast databases encoding diffusion, relaxation, and susceptibility. The results showed similar patterns of measurement-subset selection and mean-squared errors across different training sets. The increasing availability of public multi-contrast MRI databases can further push data-driven approaches in providing recommendations for experiment design. |
| 1241 | A Semi-Supervised Learning Framework for Jointly Accelerated Multi-Contrast MRI Synthesis without Fully-Sampled Ground-Truths | |
| Mahmut Yurt1,2, Salman Ul Hassan Dar1,2, Berk Tinaz1,2,3, Muzaffer Ozbey1,2, Yilmaz Korkmaz1,2, and Tolga Çukur1,2,4 | ||
1Department of Electrical and Electronics Engineering, Bilkent University, Ankara, Turkey, 2National Magnetic Resonance Research Center, Bilkent University, Ankara, Turkey, 3Department of Electrical and Computer Engineering, University of Southern California, Los Angeles, CA, United States, 4Neuroscience Program, Aysel Sabuncu Brain Research Center, Bilkent University, Ankara, Turkey |
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Current approaches for synthetic multi-contrast MRI involve deep networks trained to synthesize target-contrast images from source-contrast images in fully-supervised protocols. Yet, their performance is undesirably circumscribed to training sets of costly fully-sampled source-target images. For practically advanced multi-contrast MRI synthesis accelerated across the k-space and contrast sets, we propose a semi-supervised generative model that can be trained to synthesize fully-sampled images using only undersampled ground-truths by introducing a selective loss function expressed only on the acquired k-space coefficients randomized across training subjects. Demonstrations on multi-contrast brain images indicate that the proposed model maintains equivalent performance to the gold-standard fully-supervised model. |
| 1242 | Multi-Contrast Whole Brain MRI: Optimization of Imaging Parameters and Motion Compensation | |
| Jing Liu1, Angela Jakary1, Duan Xu1, and Janine Lupo1 | ||
1Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, United States |
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Multi-contrast anatomical brain MR images are widely used for tissue characterization and lesion detection, by applying multiple sequences. We developed a single continuous data acquisition applied with multiple inversion pulses, allowing multi-contrast imaging with high data acquisition efficiency. In order to achieve accurate tissue segmentation based on the multi-contrast images, imaging parameters are optimized based on simulated signal evolutions for achieving good image quality and accurate tissue characterization. A motion compensation approach for 3D whole-brain, multi-contrast MRI, was developed by exploiting the flexible data sampling strategy that allows for arbitrary combination of data collected throughout acquisition time and inversion times. |
| 1243 | Adaptive Multi-contrast MR Image Denoising based on a Residual U-Net using Noise Level Map | |
| Jiahao Hu1,2,3, Yilong Liu1,2, Zheyuan Yi1,2,3, Yujiao Zhao1,2, Fei Chen3, and Ed X. Wu1,2 | ||
1Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Hong Kong, China, 2Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong, China, 3Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, China |
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Multi-contrast MRI offers us images with complementary diagnostic information. Despite the dramatic difference in contrast, multi-contrast images often share highly correlated structure information. A deep learning (DL) based strategy is proposed to denoise multi-contrast MR images with flexible noise-levels using residual U-Net. This method utilizes the structural similarities across contrasts by simultaneously denoising multiple contrasts while existing single-contrast MRI denoising methods neglect the analogous structure information. The proposed method outperforms BM3D in terms of better noise reduction and details preservation. More importantly, we introduce a noise-level map that can be manually set to fit the different noise levels. |
| 1244 | Simultaneous morphological and quantitative lumbar MRI with 3D isotropic high-resolution using MIXTURE T2 | |
| Daichi Murayama1, Takayuki sakai1, Masami Yoneyama2, and Shigehiro Ochi1 | ||
1Radiology, Eastern Chiba Medical Center, Chiba, Japan, 2Philips Japan, Tokyo, Japan |
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We propose a new sequence called MIXTURE (Multi-Interleaved X-prepared TSE with inTUitive RElaxometry). MIXTURE based is a 3D TSE that can set arbitrary echo times using the T2 preparation pulses, and enables several image contrasts (such as PDW, T2W) and T2 mapping by acquiring at least two echo time images. MIXTURE could simultaneously provide morphology, pathology and T2 quantitative lumbar imaging in one single scan. This sequence is very promising to evaluate the degeneration of nerve roots and intervertebral disc for 3D T2 mapping and improve the ability of diagnostic imaging around the lumbar for 3D multi contrast MRI. |
| 1245 | Accelerated MR parametric mapping with a hybrid deep learning model | |
| Haoxiang Li1,2, Jing Chen1, Yuanyuan Liu1, Hairong Zheng1, Dong Liang1, and Yanjie Zhu1 | ||
1Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China, 2Shenzhen College of Advanced Technology, University of Chinese Academy of Sciences, Shenzhen, China |
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Magnetic Resonance (MR) parametric mapping like $$$T_1$$$ , $$$T_2$$$, proton density is a powerful tool for biology tissue characterization, which is useful for clinical application such as diagnosis of pathologies including Alzheimer’s disease and multiple sclerosis1, evaluation of myocardial fibrosis2 and assessment of knee cartilage damage3. However the long scan time makes it challenging for practical clinical application. The purpose of this study was to develop a deep learning based method for accelerated MR parametric mapping with good performance at high acceleration rate both by reducing the contrast number and undersampling the k-space data. |
| 1246 | Simultaneous 3D T1 weighted, T2 weighted and FLAIR imaging using Serial Connection of Echo Train Acquisitions (SCETA) for Multi-contrast imaging | |
| Naoyuki Takei1, Shohei Fujita2,3, Issei Fukunaga2, Mitsuharu Miyoshi1, Shigeki Aoki2, Suchandrima Banerjee4, and Tetsuya Wakayama1 | ||
1MR Applications and Workflow, GE Heatlcare, Tokyo, Japan, 2Juntendo University School of Medicine, Tokyo, Japan, 3The University of Tokyo Graduate School of Medicine, Tokyo, Japan, 4MR Applications and Workflow, GE Heatlcare, Menlo Park, CA, United States |
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To aim for accelerated brain routine MRI, a novel 3D multi-contrast imaging technique using the hybrid acquisition of FSE and GRE was proposed. The basic image contrasts commonly used in clinical practice such as T1 weighted, T2 weighted and FLAIR were acquired simultaneously. The comparison with conventional 3D imagings was performed in term of image contrast and scan time to demonstrate the proof of concept. The proposed technique potentially gives a new perspective of the use of 3D acquisition strategy. |
| 1247 | Rapid and Simultaneous Acquisition of T2-weighted and Fluid-attenuated Brain Images using a Spiral-ring Turbo Spin-echo Imaging | |
| Zhixing Wang1, Xue Feng1, John Mugler2, and Craig Meyer1 | ||
1Biomedical Engineering, University of Virginia, Charlottesville, VA, United States, 2Radiology & Medical Imaging, University of Virginia, Charlottesville, VA, United States |
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This study describes a new approach to obtain T2-weighted and fluid-attenuated inversion recovery (FLAIR) images simultaneously in a short scan time. In this technique, the Cartesian readout is replaced by an annular spiral-ring segmentation, and a 180°(y)-90°(x) preparation RF pulse at the end of the echo train is used for driven inversion, rather than a single 180° inversion pulse as used for conventional FLAIR. Both the T2-weighted and FLAIR images can be acquired in a single scan, with higher scan efficiency and similar image quality, when compared with Cartesian TSE and Cartesian FLAIR. |
| 1248 | Merging T1 weighted images with QSM provides a unique contrast for brain tissue segmentation in humans and non-human primates | |
| Rakshit Dadarwal1,2 and Susann Boretius1,2 | ||
1Functional Imaging Laboratory, German Primate Center, Göttingen, Germany, 2Georg August Universität Göttingen, Göttingen, Germany |
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Automatic brain tissue segmentations mostly rely on T1 weighted images (T1w) which provide an excellent grey matter – to -white matter contrast but T1w lacks sufficient contrast for major subcortical nuclei. Particularly in non-human primates, these segmentation approaches encounter their limits. By merging T1w with Quantitative Susceptibility Mapping, a unique brain tissue contrast could be generated. TQ-SILiCON maps allowed for an improved subcortical nuclei classification while retaining the excellent white matter delineation of T1w. The approach works equally well for humans and non-human primates. |
| 1249 | Comprehensive multiparametric cardiac MRI tissue phenotyping (LGE, T1, T2, DWI, BOLD & VAI) of acute myocardial infarction in swine | |
| Holly Doig1, Maaike van den Boomen1,2,3, Erin Connors1, Joan Kim1, Jaume Coll-Font1,3, Robert A. Eder1, Shi Chen1, Yoshiko Iwamoto1, Kyrre E. Emblem4, Kawin Setsompop3, Niek H.J. Prakken2, Ronald J.H. Borra2,5, and Christopher T. Nguyen1,3 | ||
1Cardiovascular Research Center, Massachusetts General Hospital, Boston, MA, United States, 2Department of Radiology, University Medical Center Groningen, Groningen, Netherlands, 3A.A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA, United States, 4Department of Diagnostic Physics, Oslo University Hospital, Oslo, Norway, 5Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, Groningen, Netherlands |
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Myocardial infarction (MI) and ischemic reperfusion (IR) injury are a common western world problem and are aimed to be better understood by imaging techniques to enable non-invasive longitudinal follow up. Novel MRI based techniques, such as cardiac DWI, BOLD and VAI, are emerging and detailed assessment and comparison with current golden standard and histology is needed to determine their role in treatment planning and revalidation of MI patients. Here we show that specifically BOLD can be used as an early marker in the acute MI phase. |
| 1250 | Stroke analysis with fully automatic multi-contrast MR image registration | |
| Weijian Huang1, Yulon Qi2, Qiang He3, Ting Ma4, Xin Liu1, Guanxun Cheng2, Hairong Zheng1, and Shanshan Wang1 | ||
1Paul C Lauterbur Research Center, Shenzhen Institutes of Advanced Technology Chinese Academy of Sciences, Shenzhen, China, 2Radiology department, Peking University Shenzhen Hospital, shenzhen, China, 3United Imaging Research Institute of Innovative Medical Equipment, Shenzhen, China, 4Pengcheng Laboratory, Shenzhen, China |
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Stroke is a leading cause of death and disability worldwide. However, the misalignment between multi-contrast MR images bring difficulties in identifying the lesions. We propose an automatic framework including affine and deformation transformation for multi-contrast stroke images registration. In the framework, a new inverse operation is proposed to maintain the topology of images and a background suppression loss function is designed to optimize background predictions. The method achieves the best Dice score of 0.826 compared to 5 state-of-the-art methods. Moreover, our method is about 17 times faster than the most competitive method SyN when testing on a same CPU. |
| 1251 | In-vivo ferumoxytol imaging and T1/T2 characterization at 64mT | |
| Thomas Campbell Arnold1, Samantha By2, Hadrien Dyvorne2, Rafael O'Halloran2, Farzana Sayani3, Lisa M. Desiderio4, Brian Litt1,5, and Joel M. Stein4 | ||
1Bioengineering, University of Pennsylvania, Philadelphia, PA, United States, 2Hyperfine Research, Guilford, CT, United States, 3Medicine, Perelman School of Medicine, Philadelphia, PA, United States, 4Radiology, Perelman School of Medicine, Philadelphia, PA, United States, 5Neurology, Perelman School of Medicine, Philadelphia, PA, United States |
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MRI provides superior imaging for diverse clinical applications, but cost and other factors limit availability in various healthcare and lower resource settings. Low-field strength units promise to expand access but involve trade-offs including reduced signal, longer acquisitions, and uncertain benefit of contrast agents. Here we characterize T1 and T2 properties of ferumoxytol, an iron oxide agent with prolonged blood pool phase and higher R1 and R2 values than gadolinium, on a 64mT portable system. We demonstrate enhancement across a range of concentrations in phantoms and visualization of cerebral vasculature in patients receiving the agent for iron-deficiency anemia. |
| 1252 | BOLD-free fMRI? | |
| Tobias C Wood1 and Nikou Louise Damestani1 | ||
1Neuroimaging, King's College London, London, United Kingdom |
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We demonstrate a proof-of-concept fMRI experiment using a BOLD-insensitive MT-prepared ZTE pulse sequence, which exploits the recently proposed Arterial Blood Contrast mechanism. We show tightly localised responses to a visual checkerboard task in a small number of subjects. |
| 1253 | High neuromelanin contrast achieved using sandwiched flow saturation RF pulses: sandwich-fsNM imaging | |
| Sooyeon Ji1, Eun-Jung Choi1, Eung Yeop Kim2, Dong Hoon Shin3, Hyeong-Geol Shin1, and Jongho Lee1 | ||
1Department of Electrical and Computer Engineering, Seoul National University, Seoul, Korea, Republic of, 2Department of Radiology, Gachon University Gil Medical Center, Incheon, Korea, Republic of, 3Department of Neurology, Gachon University Gil Medical Center, Incheon, Korea, Republic of |
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A neuromelanin-sensitive imaging protocol based on a GRE sequence, sandwich-fsNM, is developed using multiple flow saturation pulses instead of MT pulses. The flow saturation pulses are located both superior and inferior to the imaging volume, like a sandwich, to avoid asymmetric MT across slices. The proposed protocol yields higher contrast between crus cerebri and substantia nigra and better visualizes locus coeruleus, compared to MT prepared GRE or TSE sequences. |
| 1254 | EPR measurements on human brain tissue at variable temperature | |
| Fábio Seiji Otsuka1, Carlos Salmon1, Otaciro Nasimento2, and Maria Otaduy3 | ||
1Physics Department, University of São Paulo, Ribeirão Preto, Brazil, 2Physics Institute, University of São Paulo, São Carlos, Brazil, 3Medical School, University of São Paulo, São Paulo, Brazil |
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On this work it was evaluated the EPR measurements at variable temperature on tissue samples from different brain regions. For all samples, four different peaks were observed and their relationship with temperature were analyzed. High-spin rhombic iron(g = 4.3), copper(g = 2.06, g = 2.28) and organic radical (g = 1.989) peaks showed a Curie behavior with antiferromagnetic contributions. By other hand, a broad peak centered at g = 2.0 showed an antiferromagnetic behavior with Curie contribution. Additionally, a fifth peak was observed only for the Locus Coeruleus sample with a temperature dependent g-value (3.62 - 2.55). |
| 1255 | Radiofrequency heating measurement using MR thermometry and field monitoring: methodological considerations and first in vivo results. | |
| Caroline Le Ster1, Franck Mauconduit1, Christian Mirkes2, Michel Bottlaender3,4, Fawzi Boumezbeur1, Boucif Djemai1, Alexandre Vignaud1, and Nicolas Boulant1 | ||
1Paris-Saclay University, CEA, CNRS, BAOBAB, Neurospin, Gif-sur-Yvette, France, 2Skope MRT, Zurich, Switzerland, 3Paris-Saclay University, CEA, CNRS, INSERM, BioMaps, Service hospitalier Joliot, Orsay, France, 4UNIACT, Neurospin, CEA, Gif-sur-Yvette, France |
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An MR thermometry (MRT) method with field monitoring is proposed to improve the measurement of small temperature variations occurring in head MRI exams. MRT experiments were performed at 7T with concurrent radiofrequency heating and field monitoring on an agar-gel phantom and on an anaesthetized macaque. Inclusion of field fluctuations in image reconstruction showed beneficial for the measurement of small temperature rises as encountered in standard brain exams. |
| 1256 | Experimental Evaluation of Spin Echo based Magnetic Resonance Magnetohydrodynamic Flow Velocimetry | |
| Mert Şişman1, Mehdi Sadighi1, Hasan Hüseyin Eroğlu2,3, and B. Murat Eyüboğlu1 | ||
1Electrical and Electronics Engineering, Middle East Technical University (METU), Ankara, Turkey, 2Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital, Amager and Hvidovre, Denmark, 3Center for Magnetic Resonance, DTU Health Tech, Technical University of Denmark, Kgs Lyngby, Denmark |
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Magnetohydrodynamic (MHD) flow occurs due to the Lorentz force formed by the interaction between the static magnetic field of the MR scanner and the externally injected electric current. The MR based imaging of MHD flow has become a research field of interest recently. The MHD flow can be extracted from the MR phase images obtained using a pulse sequence with flow-encoding gradients. In this study, the MHD flow distributions of a simulated model and a homogeneous experimental phantom are obtained. The MHD velocity contrast images reconstructed using simulated and experimental measurements are consistent. |
| 1257 | Simultaneous Magnetic Resonance Magnetohydrodynamic Flow Velocity and Diffusion Tensor Imaging | |
| Mert Şişman1, Mehdi Sadighi1, and B. Murat Eyüboğlu1 | ||
1Electrical and Electronics Engineering, Middle East Technical University (METU), Ankara, Turkey |
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Recently, it is shown that the magnetohydrodynamic (MHD) flow has potential in clinical applications. In addition, diffusion tensor imaging (DTI) is widely used as an exclusive clinical diagnostic method. To obtain the MHD flow velocity distributions in three directions, twelve acquisitions with flow-encoding gradients and external current injection are needed. By choosing flow-encoding directions carefully, it is possible to obtain MHD flow velocity and DT distributions from the MR phase and magnitude images of the same acquisition. In this study, the MHD flow and DT data of an imaging phantom are acquired simultaneously using a spin echo based pulse sequence. |
| 1258 | Theoretical evaluation of the feasibility to detect label-exchange by proton MRS at 7T in human brain after administration of deuterated glucose. | |
| Simone Poli1, Lia Bally2, Roland Wiest3, and Roland Kreis1 | ||
1Department of Radiology and Biomedical Research, University of Bern, Bern, Switzerland, 2Department of Diabetes, Endocrinology, Nutritional Medicine and Metabolism, Inselspital, Bern University Hospital and University of Bern, Bern, CH, Bern, Switzerland, 3Institute of Diagnostic and Interventional Neuroradiology, Inselspital, Bern University Hospital and University of Bern, Bern, CH, Bern, Switzerland |
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This study aims to analyze the feasibility of indirect detection by 1H MRS of cerebral metabolism following intake of deuterated glucose in humans on a clinical 7T system. Brain spectra before and after [6,6’-2H2]-glucose administration were simulated with realistic SNR and linewidth to evaluate the best achievable precision in quantifying specific deuterated and non-deuterated metabolites. We expect labeling of glutamate, lactate and glutamine to be observable from single spectra of large VOIs, but also in MRSI at resolutions of 2-5 cm3. The simulations were corroborated with phantom data but eventual feasibility will remain to be confirmed in vivo. |
| 1259 | Relaxation Anisotropy in Biological Tissues | |
| Nina Elina Hänninen1,2, Mikko Johannes Nissi1,2, Matti Hanni1,3,4, Olli Gröhn5, Miika Tapio Nieminen1,3,4, and Timo Liimatainen1,4 | ||
1Research Unit of Medical Imaging, Physics and Technology, University of Oulu, Oulu, Finland, 2Department of Applied Physics, University of Eastern Finland, Kuopio, Finland, 3Medical Research Center, University of Oulu and Oulu University Hospital, Oulu, Finland, 4Department of Diagnostic Radiology, Oulu University Hospital, Oulu, Finland, 5A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland |
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Relaxation times of tissues can depend on tissue orientation with respect to main magnetic field. However, these effects are still unknown in many biological tissues. Relaxation anisotropy provides a base to develop novel quantitative MRI contrasts and unwrap the theory behind different relaxation mechanisms. We investigated relaxation anisotropy of conventional and rotating frame relaxation parameters in brain, spinal cord, tendon, cartilage, kidney and cardiac muscle tissue. The findings show that relaxation anisotropy varies between relaxation parameters and between different tissue types. |
| 1260 | Towards high precision thermal based RF safety assessment with cardiac triggered MR thermometry | |
| Bart R. Steensma1, Cornelis A.T. van den Berg1, and Alexander J.E. Raaijmakers2 | ||
1Center for Image Sciences - Computational Imaging Group, University Medical Center Utrecht, Utrecht, Netherlands, 2Biomedical Engineering - Medical Imaging Analysis, Eindhoven University of Technology, Eindhoven, Netherlands |
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To validate thermal simulations, high precision in vivo MR thermometry measurements are required. We demonstrate in vivo MR thermometry in the upper leg at 7T, where we improved the precision of our temperature measurements by using cardiac triggering with a PPU. The standard deviation in baseline measurements without RF heating decreased more than two-fold (0.1 ° C with PPU compared to 0.21 ° C without PPU). We were able to perform reproducible MR thermometry measurements in vivo, with local temperature increases of less than 1 °C. |
| 1261 | Virtual non-contrast enhanced MRI (VNC-MRI) | |
| Thomas Lindner1, Hanna Debus1, and Jens Fiehler1 | ||
1University Hospital Hamburg-Eppendorf, Hamburg, Germany |
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This study presents an approach to retrospectively remove contrast agent from the final images, denoted as "virtual non-contrast enhanced imaging" |
| 1262 | Monte Carlo Simulation for Magnetic Nanoparticle Biosensors | |
| Tristhal Parasram1, Rongsheng Lu2, Yi Chen2, and Dan Xiao1 | ||
1University of Windsor, Windsor, ON, Canada, 2Southeast University, Nanjing, China |
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Magnetic nanoparticles can bind to biomarkers. The particles dispersed in solution become clustered if the targets exist, leading to a different T2 relaxation time. The relaxation switch mechanism has been applied as a biosensor for various biomarkers. However, the change in relaxation rate is related to the nanoparticle size and concentration. Some theoretical models have been applied to predict this rate of change in search for the optimal system parameters. In this work, an open-source Monte Carlo algorithm has been developed to simulate water diffusion in microscopic environments with nanoparticles and the effective T2 relaxation times. |
| 1263 | Feasibility of Magnetic Resonance Thermometry at 0.55T | |
| Waqas Majeed1, Axel J. Krafft2, Sunil Patil1, Henrik Odéen3, John Roberts3, Florian Maier2, Dennis L. Parker3, and Himanshu Bhat1 | ||
1Siemens Medical Solutions USA Inc., Malvern, PA, United States, 2Siemens Healthcare GmbH, Erlangen, Germany, 3Department of Radiology and Imaging Sciences, University of Utah, Salt Lake City, UT, United States |
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Low field MRI offers advantages such as reduced cost and improved safety of implantable and interventional devices, and reduced RF energy deposition over high field alternatives. However, the accuracy of proton resonance frequency (PRF) thermometry suffers at low field due to reduced signal to noise ratio as well as lower temperature-sensitivity of MR phase. In this study we demonstrate that reduced off-resonance effects, increased T2* and shorter T1 associated with low field can be leveraged to achieve high quality MR thermometry in the brain and prostate at 0.55T. |
| 1264 | Improved PRF-based MR Thermometry for Tissues with Aqueous and Adipose | |
| Chang-Sheng Mei1, Shenyan Zong2, and Guofeng Shen2 | ||
1Department of Physics, Soochow University, Taipei, Taiwan, 2Biomedical Instrument Institute, School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China |
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The proton resonance frequency (PRF) offset, which is linear to the temperature changes, has been developed and applied for thermal ablation therapies. However, the conventional PRF-based thermometry is limited in temperature measurements of fat due to the absence of hydrogen bonds. In this work, we proposed a revised and retrospective PRF method merged with the nonlinear circle fitting, to detect the accurate phase changes of water for achieving temperature measurements in aqueous and adipose tissues. The in vitro water-bathing heating for phantom and ex vivo focused ultrasound (FUS) heating for swine tissues were performed to verify the proposed method. |
| 1265 | Effects of T2* on accuracy of single reference variable flip angle T1 – mapping for MR thermometry | |
| Michael Malmberg1, Dennis L Parker2, and Henrik L Odéen2 | ||
1Biomedical Engineering, University of Utah, Salt Lake City, UT, United States, 2Radiology and Imaging Sciences, University of Utah, Salt Lake City, UT, United States |
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Neglecting the effects of T2* changes in the single reference variable flip angle (SR-VFA) method for T1-mapping produces a substantial systematic bias on T1 that increases with TE, T1 changes, and T2* changes. These effects were simulated using 1000 noisy signals of a single voxel using the SPGR equation. It was found that the bias can be corrected by measuring T2* changes dynamically, at the expense of noise, which noise could be mitigated through weighted T1-map combinations across echo times. Multi-echo T1-mapping with the SR-VFA method could be combined with PRFS thermometry to allow fast, accurate T1-mapping of heterogeneous tissue. |
| 1266 | Accuracy of MR thermometry during deep radiofrequency hyperthermia treatments in the pelvic region | |
| Iva VilasBoas-Ribeiro1, Sergio Curto1, Gerard C. van Rhoon1,2, and Margarethus M. Paulides1,3 | ||
1Department of Radiotherapy, Erasmus MC Cancer Institute, University Medical Center Rotterdam, Rotterdam, Netherlands, 2Department of Radiation Science and Technology, Faculty of Applied Sciences, Delft University of Technology, Delft, Netherlands, 3Center for Care and Cure Technologies Eindhoven (C3Te), Department of Electrical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands |
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Proton resonant frequency shift is the most frequently used method for MR-thermometry. This method is sensitive to patient motion which poses issues that affect the MR-thermometry accuracy. Few studies have evaluated MR thermometry in the pelvis, but only in volumes far from the regions with air motion, and without an objective patient data exclusion criteria. In this study, we assessed accuracy of MR thermometry for a selected group of patients with cervical carcinoma. We showed that changing gastrointestinal air volume was an important confounder for MR thermometry accuracy and that this can be exploited for selection criteria prior to treatment. |
| 1267 | Towards correlating tissue status with dynamic PRF-T1 measurements using a single reference dual flip angle technique | |
| Henrik Odéen1, Sara L Johnson1, Allison H Payne1, and Dennis L Parker1 | ||
1Radiology and Imaging Sciences, University of Utah, Salt Lake City, UT, United States |
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Simultaneous PRF/T1 measurements using a single reference variable flip angle method is used to investigate the utility of T1 as a complimentary measure to thermometry for treatment outcome in MR guided thermal interventions, such as focused ultrasound. Both temperature and thermal dose have been shown to be inaccurate indicators of treatment outcome, creating a potential need for alternative quantitative metrics. This can be of particular value in adipose tissues where PRF has very low sensitivity. It is shown that the slope of the T1 vs. temperature curve correlates with amount of delivered thermal dose. |
| 1268 | Analysis of neurodegeneration using diffusion and functional MRI in FTLD model marmoset | |
| Mitsuki Rikitake1, Junichi Hata2, Fumiko Seki3, Shinsuke Ishigaki4, Kuniyuki Iwata-Endo4, Nobuyuki Iwade4, Takako Shirakawa1, Hirotaka James Okano2, Hideyuki Okano5, and Gen Sobue4 | ||
1Department of Redioligical Science, Human Health Science, Tokyo Metroplitan University, Tokyo, Japan, 2Jikei University Graduate School of Medicine, Tokyo, Japan, 3Central Institute for Experimental Animals, Kanagawa, Japan, 4Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya, Japan, 5RIKEN Center of Brain Science, Saitama, Japan |
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Symptom of FTLD is known brain atrophy and neurodegeneration predominantly in frontal and temporal lobes.However, the regularity of neurodegeneration and image analysis methods have not been established.The purpose of this study was to conduct multiparametric MRI to analyze the neurodegeneration caused by FTLD using structural MRI and fMRI.We used marmosets, which have a relatively similar brain structure to humans, as the experimental subjects.Statistical imaging analysis using diffusion MRI showed gray matter degeneration was observed, mainly in the caudate nucleus.The fMRI showed decreased brain activity in the frontal lobe and basal ganglia. |
| 1269 | The Use of the 3He/129Xe MRI Lung Morphometry for a Longitudinal Observation of the Emphysema Progression in AATD Patients | |
| Elise Noelle Woodward1, Matthew S Fox1,2, Tingting Wu3, Hacene Serrai1, David G McCormack4, Grace Parraga3,4,5,6, and Alexei Ouriadov1,2,6 | ||
1Physics and Astronomy, Western University, London, ON, Canada, 2Lawson Health Research Centre, London, ON, Canada, 3Department of Medical Biophysics, Western University, London, ON, Canada, 4Department of Medicine, Respirology, Western University, London, ON, Canada, 5Robarts Research Institute, London, ON, Canada, 6School of Biomedical Engineering, Western University, London, ON, Canada |
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In this study, we demonstrated a possible solution to underestimation of the global mean that can mask the severity of emphysema progression. Four patients with Alpha-1 Anti-Trypsin Deficiency disorder (AATD) were measured in 2014 using hyperpolarized He to measure lung function, and again in 2018 to measure lung function. While it is evident looking at morphometry images that there is a significant reduction in pixels and therefore emphysema progression, it is not at first evident in morphometry estimates. By normalizing these morphometry estimates of ADC/Lm, we can better characterize emphysema progression in individuals with AATD |
| 1270 | Metabolite-specific echo planar imaging of hyperpolarized 13C-pyruvate at 4.7T | |
| Tyler Blazey1, Galen D Reed2, Joel R Garbow1, and Cornelius von Morze1 | ||
1Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, MO, United States, 2GE Healthcare, Dallas, TX, United States |
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Hyperpolarization greatly increases the sensitivity of MRI studies of 13C-labeled substances. To expand our ability to investigate in vivo metabolism with hyperpolarized MRI, we developed a metabolite-specific 2D EPI pulse sequence with custom flyback spatially-selective RF pulses for [1-13C]pyruvate and [1-13C]lactate at 4.7T. Spectral profiles for each metabolite obtained using a [13C]urea phantom showed good correspondence with simulated profiles. In vivo testing was performed by imaging the liver and kidney of a rat following the injection of hyperpolarized [1-13C]pyruvate. Both the temporal and spatial resolution of [1-13C]pyruvate and [1-13C]lactate images was higher with our metabolite-specific EPI sequence than with CSI. |
| 1271 | Feasibility of model-based omega-3 fatty acid fraction mapping using multi-echo gradient-echo imaging at 3T | |
| Dominik Weidlich1, Julius Honecker2, Claudine Seeliger2, Daniela Junker1, Marcus R. Makowski1, Hans Hauner2, Dimitrios C. Karampinos1, and Stefan Ruschke1 | ||
1Department of Diagnostic and Interventional Radiology, School of Medicine, Technical University of Munich, Munich, Germany, 2Else Kröner Fresenius Center for Nutritional Medicine, Technical University of Munich, Freising, Germany |
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A non-invasive method allowing the probing of the relative ω-3 fatty acid content in adipose tissue has the potential to reveal unknown metabolic patterns in physiology and pathology. In the current study, a model-based triglyceride mapping scheme is extended to enable the differentiation between ω-3 and non-ω-3 fatty acids by exploiting additional knowledge about the chemical shift properties. This extended scheme is combined with a chemical shift encoding imaging sequence and evaluated in a phantom validation experiment against gas chromatography–mass spectrometry. Furthermore, feasibility is demonstrated in both in vitro and in vivo settings. |
| 1451 | DeepCEST: 7T Chemical exchange saturation transfer MRI contrast inferred from 3T data via deep learning with uncertainty quantification | |
| Leonie E. Hunger1, Alexander German1, Felix Glang2, Katrin M. Khakzar1, Nam Dang1, Angelika Mennecke1, Andreas Maier3, Frederik Laun4, and Moritz Zaiss1,2 | ||
1Department of Neuroradiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany, 2High-field Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany, 3Pattern Recognition Lab, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany, 4Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany |
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The deepCEST approach enables to perform CEST experiments at a lower magnetic field strength and predict the contrasts of a higher field strength. This is possible through the application of a neural network, which was trained with low and high B1 Z-spectra acquired at 3T as input data, and as target data 5-pool-Lorentzian fitted amplitudes obtained from 7T spectra were used. The network included an uncertainty quantification to verify the reliability of the predicted images. |
| 1452 | Reduction of 7T CEST scan time and evaluation by L1-regularised linear projections | |
| Moritz Simon Fabian1, Felix Glang2, Katrin Michaela Khakzar1, Angelika Barbara Mennecke1, Alexander German1, Manuel Schmidt3, Burkhard Kasper4, Arnd Dörfler1, Frederik B. Laun1, and Moritz Zaiss1 | ||
1Department of Neuroradiology, University Hospital Erlangen, Friedrich Alexander University Erlangen-Nürnberg, Erlangen, Germany, 2High-field Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Tübungen, Germany, 3Department of Neuroradiology, University Hospital Erlangen, Erlangen, Germany, 4Department of Neurology, Epilepsy Center, University Hospital Erlangen, Erlangen, Germany |
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Measurement and evaluation of multi-parametric CEST protocols requires complex and time consuming processing for correction of field inhomogeneities and contrast generation. In this work, we expand the linear projection approach for mapping motion corrected 7T CEST data directly to Lorentzian target parameters by L1-regularisation. This translates to subsampling in the frequency offset domain, resulting in reduced acquisition time. The method generalizes from healthy subject training data to unseen healthy test data and a tumor patient dataset. The L1-regularized linear projection approach integrates shortcutting of B0 and B1 correction, denoising, and Lorentzian fitting. It enforces sparsity of required frequency offsets. |
| 1453 | Open source Pulseq interpreter for CEST MRI on Bruker systems | |
| Sebastian Mueller1, Kai Herz1, Klaus Scheffler1,2, and Moritz Zaiss1,3 | ||
1High-field Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Tuebingen, Germany, 2Department of Biomedical Magnetic Resonance, Eberhard Karls University Tuebingen, Tuebingen, Germany, 3Department of Neuroradiology, University Hospital Erlangen, Erlangen, Germany |
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CEST MRI becomes a frequently applied tool, however, a lot of method development is still done on pre-clinical scanners. Here we propose an approach that allows a fully automatic combination of existing MRI readouts for Bruker systems with open source pulseq-files for definition of CEST pre-saturation, without additional sequence programming. We believe that our work facilitates both basic research on CEST MRI and straightforward implementation of sophisticated, precisely defined CEST experiments on Bruker systems. Additionally, the use of Pulseq provides a universal, sharable standard to run the exact same pre-saturation in simulations and on clinical devises at a later stage. |
| 1454 | Linear projection-based CEST reconstruction – the simplest explainable AI | |
| Felix Glang1, Moritz Fabian2, Alex German2, Katrin Khakzar2, Angelika Mennecke2, Frederik Laun3, Burkhard Kasper4, Manuel Schmidt2, Arnd Doerfler2, Klaus Scheffler1,5, and Moritz Zaiss1,2 | ||
1High-field Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany, 2Department of Neuroradiology, University Hospital Erlangen, Erlangen, Germany, 3Institute of Radiology, University Hospital Erlangen, Erlangen, Germany, 4Neurology, Epilepsy Center, University Clinic of Friedrich Alexander University Erlangen-Nürnberg, Erlangen, Germany, 5Department of Biomedical Magnetic Resonance, Eberhard Karls University Tübingen, Tübingen, Germany |
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Evaluation of multi-parametric in vivo CEST MRI often requires complex computational processing for both field inhomogeneity correction and contrast generation. In this work, linear regression was used to obtain coefficient vectors that directly map uncorrected 7T spectra to corrected Lorentzian target parameters by simple linear projection. The method generalizes from healthy subject training data to unseen test data of both healthy subjects and tumor patients. The linear projection approach thus integrates correction of both B0 and B1 inhomogeneity as well as contrast generation in a single fast and interpretable computation step. |
| 1455 | In-Vivo Sub-Minute rNOE Mapping Using AutoCEST: a Machine-Learning Approach for CEST/MT Protocol Invention and Quantitative Reconstruction | |
| Or Perlman1, Bo Zhu1,2, Moritz Zaiss3,4, Naoyuki Shono5, Hiroshi Nakashima5, E. Antonio Chiocca5, Matthew S. Rosen1,2, and Christian T. Farrar1 | ||
1Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, United States, 2Department of Physics, Harvard University, Cambridge, MA, United States, 3Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany, 4Department of Neuroradiology, University Clinic Erlangen, Erlangen, Germany, 5Brigham and Women’s Hospital and Harvard Medical School, Boston, MA, United States |
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The long acquisition-time and the semi-quantitative nature of the typical CEST-MRI experiment constitute a major obstacle for its clinical adoption. Recently, a machine-learning approach termed AutoCEST was developed, for the automatic design of the optimal acquisition schedule and the reconstruction of quantitative 2-pool CEST maps. Here, we expand this approach for in-vivo scenarios, by incorporating the semisolid-pool into the underlying computational-graph and allowing 3 pools. AutoCEST was evaluated for quantitative rNOE mapping using a GBM mouse model, resulting in a total acquisition and reconstruction times of 49.15s. The tumor rNOE volume-fraction was significantly decreased, in agreement with previous human studies. |
| 1456 | Whole-Brain Steady-State CEST at 3T Using MR Multitasking | |
| Pei Han1,2, Karandeep Cheema1,2, Hsu-Lei Lee1, Zhengwei Zhou1, Tianle Cao1,2, Sen Ma1, Nan Wang1, Anthony G. Christodoulou1,2, and Debiao Li1,2 | ||
1Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, United States, 2Department of Bioengineering, UCLA, Los Angeles, CA, United States |
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We propose a fast 3D steady-state CEST (ss-CEST) method at 3T using MR Multitasking. By exploiting the correlation among images throughout the spatial, time, and offset frequency dimensions, the low-rank tensor framework shows a possibility for at least 2x acceleration of ss- CEST. High-quality quantitative maps can be generated from ss-CEST images. The Z-spectrum acquisition with whole-brain coverage can be done within 5.5min. |
| 1457 | Deep Learning-based image reconstruction improves CEST MRI | |
| Shu Zhang1, Xinzeng Wang2, F. William Schuler1, R. Marc Lebel3, Mitsuharu Miyoshi4, Ersin Bayram2, Elena Vinogradov5, Jason Michael Johnson6, Jingfei Ma7, and Mark David Pagel1,7 | ||
1Cancer Systems Imaging, MD Anderson Cancer Center, Houston, TX, United States, 2Global MR Applications & Workflow, GE Healthcare, Houston, TX, United States, 3Global MR Applications & Workflow, GE Healthcare, Calgary, AB, Canada, 4Global MR Applications & Workflow, GE Healthcare Japan, Tokyo, Japan, 5Radiology, UT Southwestern Medical Center, Dallas, TX, United States, 6Neuroradiology, MD Anderson Cancer Center, Houston, TX, United States, 7Imaging Physics, MD Anderson Cancer Center, Houston, TX, United States |
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Chemical exchange saturation transfer (CEST) measurements can be compromised by a low signal-to-noise ratio (SNR) due to the small CEST contrast in vivo. Deep learning-based image reconstruction (DL Recon) can enhance image SNR without losing image resolution or altering the image contrast, hence has the potential to improve quantitative CEST measurements. In this study, we investigated the improvement to CEST quantitation by DL Recon in glioma patients. We found that DL Recon substantially reduced the noise in the MTRasym maps and improved the lesion conspicuity. |
| 1458 | Indirect Inference of Acidification in Exercised Skeletal Muscle using Creatine CEST | |
| Dushyant Kumar1, Ryan Armbruster1, Neil Wilson2, Ravi Prakash Reddy Nanga1, and Ravinder Reddy1 | ||
1Radiology, University of Pennsylvania, Philadelphia, PA, United States, 2Siemens Medical Solutions USA Inc, Malvern, PA, United States |
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Intracellular acidosis, mainly due to lactic acid accumulation, has been regarded as the major contributor of skeletal muscle fatigue and may be a contributing factor across many musculoskeletal disorders, such as peripheral arterial disease (PAD), Duchenne dystrophy and Becker dystrophy, primary mitochondrial disorders, diabetes mellitus, and cardiovascular disease. Hence, an imaging biomarker capable of inferring the underlying acidification during varying exercise conditions could be valuable in assessing the efficacy of potential therapy options. Here, we demonstrate the feasibility of indirect detection of acidification in exercised skeletal muscle using creatine CEST. |
| 1459 | Simultaneous mapping of B0, B1 and T1 for the correction of CEST-MRI | |
| Kerstin Heinecke1, Henrik Narvaez1, Christoph Kolbitsch1, and Patrick Schuenke1 | ||
1Physikalisch-Technische Bundesanstalt (PTB), Braunschweig and Berlin, Germany |
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One of the bottlenecks in Chemical Exchange Saturation Transfer (CEST) MRI is its susceptibility to magnetic field inhomogeneities and dependency on T1 relaxation times. To enable efficient correction for these parameters, we propose a new method for simultaneous quantitative mapping of B0, B1 and T1 using a simple CEST sequence with a modified preparation block. For the analysis, we developed a neural network that provides an additional uncertainty estimation for each parameter. First results on phantom simulations demonstrate the feasibility of this approach as well as its applicability for the correction of CEST-MRI data. |
| 1460 | Quasi-steady-state (QUASS) CEST solution improves the accuracy of CEST quantification – QUASS CEST MRI-based omega plot analysis | |
| Phillip Zhe Sun1 | ||
1Department of Radiology and Imaging Sciences, Emory University, Atlanta, GA, United States |
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CEST MRI omega plot quantifies the labile proton fraction ratio (fr) and exchange rate (ksw), yet it assumes long RF saturation time (Ts) and relaxation delay (Td). Our study aimed to test if a quasi-steady-state (QUASS) CEST analysis that accounts for the effect of finite Ts and Td could improve the accuracy of CEST MRI quantification. Both simulation and CEST MRI experiments confirmed that the QUASS solution enabled robust quantification of ksw and fr, superior over the omega plot analysis based on the conventional apparent CEST MRI measurements. |
| 1461 | MTC removed and exchange rate differentiated CEST using Variable Delay Multi Pulse (VDMP) in the human brain at 7T | |
| Bárbara Schmitz Abecassis1, Elena Vinogradov Vinogradov2,3, Jannie P. Wijnen4, Thijs van Harten1, Evita C. Wiegers4, Hans J.M. Hoogduin4, Matthias J.P. van Osch 1, and Ece Ercan1 | ||
1Department of Radiology, Leiden University Medical Center, Leiden, Netherlands, 2Department of Radiology, UT Southwestern Medical Center, Dallas, TX, United States, 3Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, TX, United States, 4Department of Radiology, University Medical Center Utrecht, Utrecht, Netherlands |
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Variable-delay multi-pulse (VDMP) is a chemical exchange saturation transfer (CEST) editing technique relying on the exchange rate as a filter to separate the CEST- effect from different solute pools. We investigated this method to evaluate CEST-effects from metabolites and proteins in in vivo human brain at 7T. We removed the pronounced magnetization transfer contrast present in vivo via Lorentzian-fittings, and evaluated the effect of B1 on saturation build-up curves of the different CEST-pools. MTC-removed VDMP-curves from the human brain are reported for the first time, where the effect of slow and fast exchanging protons allows distinguishing different CEST-pools. |
| 1462 | Highly Accelerated 1mm3-Isotropic 3D CEST MRI with Spectral Random Walk CAIPIRINHA Sampling at 7T | |
| Sugil Kim1, Seong-Gi Kim2,3, and Suhyung Park4,5 | ||
1Siemens Healthineers, Seoul, Korea, Republic of, 2Center for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon, Korea, Republic of, 3Department of Biomedical Engineering, Sungkyunkwan University, Suwon, Korea, Republic of, 4Department of Computer Engineering, Chonnam National University, Gwangju, Korea, Republic of, 5Department of ICT Convergence System Engineering, Chonnam National University, Gwangju, Korea, Republic of |
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We propose highly accelerated 3D CEST MRI using CAIPI sampling based 3D segmented EPI with spectral random walk, potentially enabling 1mm-isotropic whole-brain CEST imaging within 5min at 7T. |
| 1463 | Mapping of intracellular pH in vivo using amide and guanidyl CEST-MRI at 9.4 T | |
| Philip S Boyd1, Johannes Breitling1, Stephanie Laier2, Karin Mueller-Decker2, Andrey Glinka3, Mark E Ladd1, Peter Bachert1, and Steffen Goerke1 | ||
1Division of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany, 2Center for Preclinial Research, Core Facility Tumor Models, German Cancer Research Center (DKFZ), Heidelberg, Germany, 3Division of Molecular Embryology, German Cancer Research Center (DKFZ), Heidelberg, Germany |
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In this study, we present a method for mapping intracellular pH values based on amide and guanidyl CEST-MRI which simultaneously compensates for concentration changes, the semi-solid magnetization transfer, and spillover dilution. Compensation of the concomitant effects and calculation of reliable pH maps in the range of pH 6.5-7.5 was verified experimentally in porcine brain lysates. Applicability in vivo was demonstrated in the lesions of three tumor-bearing mice showing an average intracellular pH of approximately 7. Consequently, endogenous amide and guanidyl signal-based mapping of the intracellular pH is now applicable for tumor imaging which was previously prevented by the concomitant effects. |
| 1464 | 7 tricks for 7T CEST: improving the reproducibility of multi-pool evaluation | |
| Angelika Mennecke1, Katrin Khakzar1, Kai Herz2, Moritz Fabian1, Alexander German1, Andrzej Liebert3, Ingmar Blümcke4, Burkhard Kasper5, Manuel Schmidt1, Arnd Dörfler1, Armin Nagel3, Frederik Laun3, and Moritz Zaiß1 | ||
1Department of Neuroradiology, University Hospital of Erlangen, FAU Erlangen-Nürnberg, Erlangen, Germany, 2High-field Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany, 3Institute of Radiology, University Hospital of Erlangen, FAU Erlangen-Nürnberg, Erlangen, Germany, 4Institute of Neuropathology, University Hospital of Erlangen, FAU Erlangen-Nürnberg, Erlangen, Germany, 5Department of Neurology, Epilepsy Centre, University Hospital of Erlangen, FAU Erlangen-Nürnberg, Erlangen, Germany |
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With the help of the presented post-processing procedure, it is possible to obtain an increased reproducibility. For the amide contrast, the CoV decreased from 4% to less than 1.2 %. |
| 1465 | Pulseq-CEST: Towards multi-site multi-vendor compatibility and reproducibility of CEST experiments using an open source sequence standard | |
| Kai Herz1,2, Sebastian Mueller1, Maxim Zaitsev3, Linda Knutsson4,5, Jinyuan Zhou5, Phillip Zhe Sun6, Peter van Zijl5,7, Klaus Scheffler1,2, and Moritz Zaiss1,8 | ||
1Magnetic Resonance Center, MPI for Biological Cybernetics, Tuebingen, Germany, 2Biomedical Magnetic Resonance, University of Tuebingen, Tuebingen, Germany, 3Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria, 4Medical Radiation Physics, Lund University, Lund, Sweden, 5Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, United States, 6Yerkes Imaging Center, Emory University, Atlanta, GA, United States, 7F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States, 8Neuroradiology, Friedrich‐Alexander Universität Erlangen‐Nuernberg, Erlangen, Germany |
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The design of the preparation period is crucial for a CEST experiment, thus, a common, easy-to-use and vendor-independent file format to share exact preparation parameters is desirable. Here, we propose the use of Pulseq to define CEST parameters in an open source and human-readable file format. By providing a protocol database, a pulseq-compatible Bloch-McConnell simulation and a hybrid sequence using Pulseq for CEST preparation, we present a straightforward approach to standardize, share, simulate and measure different CEST preparation schemes, which are inherently completely defined. |
| 1466 | Assessment of acquisition strategies of CEST MR fingerprinting pH imaging using Cramer-Rao Bound algorithm | |
| Jie Liu1, Hui Liu2, Qi Liu2, Jian Xu2, Hairong Zheng1, and Yin Wu1 | ||
1Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China, 2United Imaging Healthcare America, Houston, TX, United States |
||
Optimization of acquisition strategies plays a key role in CEST-MRF imaging. However, an effective method to assess the performance of acquisition strategies in CEST quantification is lacking. In this study, we proposed a Cramer-Rao bound (CRB) based metric to measure the accuracy of CEST-MRF in pH quantification under various acquisition schemes. The results of both simulation and phantom experiments showed that the CRB-based index outperformed the conventionally used dictionary similarity metrics that are measured with dot products and Euclidean distance, implying that the proposed algorithm has great potential in optimizing CEST-MRF imaging for improved pH measurement. |
| 1467 | A comparison of several tumor endogenous pH mapping methods using CEST at 11.7T | |
| Ying Liu1,2, Botao Zhao1,2, and Xiao-Yong Zhang1,2 | ||
1Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, China, 2Key Laboratory of Computational Neuroscience and Brain-Inspired Intelligence (Fudan University), Ministry of Education, Shanghai, China |
||
CEST-MRI has emerged as a noninvasive pH imaging technique based on the pH-dependence of the prototropic exchange rates. In this work, we compared several recently published CEST pH imaging methods and proton exchange rate value in rat glioma models at 11.7T. All of these pH-weighted contrasts show a pH correlation and have significantly different signal intensities between the tumor region and the surrounding normal tissue. Our results demonstrated that pH enhanced method and APT imaging are not concentration-independent while the sensitivity of AACID is affected by the weak amine signals at 2.7ppm. |
| 1468 | Whole-brain amide CEST at 3T with a steady-state radial MRI acquisition | |
| Ran Sui1,2,3, Lin Chen1,2, Yuguo Li1,2, Jianpan Huang4, Kannie W.Y Chan2,4, Xiang Xu5, Peter C.M.van Zijl1,2, and Jiadi Xu1,2 | ||
1F.M. Kirby Research Center for Functional Brain Imagin, Kennedy Krieger Institute, Baltimore, MD, United States, 2Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, United States, 3Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, United States, 4Department of Biomedical Engineering, City University of Hong Kong, Hong Kong, China, 5BioMedical Engineering and Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States |
||
We aim to develop an acquisition and processing pipeline for amideCEST mapping on human brain at 3T. This includes steady-state radial CEST (starCEST) using PROPELLOR-based sampling to acquire Z-spectra that are robust to brain motions and one multi-linear singular value decomposition (MLSVD) post-processing for enhancing the CEST SNR. Finally, the amideCEST peak was quantified using the polynomial and Lorentzian line-shape fitting (PLOF) approach.The amideCEST contrast extracted by the PLOF method trended towards a stronger gray matter (GM) signal (1.33% ± 0.34%) than white matter (WM) (0.92% ± 0.09%; p=0.06, n=4). |
| 1469 | Investigating MT and CEST Characteristics of DU145 Prostate Tumour Xenografts in Relation to Radiation Treatment Response | |
| Leedan Murray1, Wilfred W. Lam1, and Greg J. Stanisz1,2 | ||
1Physical Sciences, Sunnybrook Research Institute, Toronto, ON, Canada, 2University of Toronto, Toronto, ON, Canada |
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MT and CEST characteristics of DU145 prostate tumour xenografts with known responses to radiation treatment were investigated to determine characteristics that may predict treatment response. After excision for histology, tumours were categorized according to their response to treatment (responder, partial responder and non-responder). Average MTR, qMT parameters, and CEST and rNOE contributions were calculated for each category. Significant changes were mostly observed in the necrotic/apoptotic regions of the tumour and were most evident in the qMT parameters. It may be possible to determine efficacy early on in the course of treatment based on the studied MR characteristics. |
| 1470 | An ASL and CrCEST combined protocol at 3T in the Study of Metabolic and Perfusion Changes Post Revascularization in Peripheral Arterial Disease | |
| Helen Sporkin1, Toral Patel2, Christopher Schumann2, Christopher Kramer2,3, and Craig Meyer1,3 | ||
1Biomedical Engineering, University of Virginia, Charlottesville, VA, United States, 2Cardiovascular Medicine, University of Virginia, Charlottesville, VA, United States, 3Radiology and Medical Imaging, University of Virginia, Charlottesville, VA, United States |
||
Patients with peripheral arterial disease (PAD) have been shown to have a delayed phosphocreatine recovery due to chronic ischemia. Creatine chemical exchange saturation transfer (CrCEST) is an MRI technique that allows for creatine concentrations to be monitored at high spatial resolution. Combining ASL and CrCEST in the same protocol allows for spatial visualization of metabolism and perfusion. The goal of this study is to use this combination to assess changes after revascularization in patients undergoing both endovascular and surgical procedures and evaluate the recovery of both perfusion and metabolism in their muscle tissue. |
| 1471 | Accelerating T1ρ mapping using patch-based low-rank tensor | |
| Yuanyuan Liu1, Zhuo-Xu Cui1, Xin Liu1, Dong Liang1, and Yanjie Zhu1 | ||
1Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China |
||
T1ρ mapping requires the acquisition of multiple T1ρ-weighted images with different spin lock times to obtain the T1ρ maps, resulting in a long scan time. Compressed sensing has shown good performance in fast quantitative T1ρ mapping. In this study, we used a patch-based low-rank tensor imaging method to reconstruct the T1ρ-weighted images from highly undersampled data. Preliminary results show that the proposed method achieves a 6-fold acceleration and obtains more accurate T1ρ maps than the existing methods. |
| 1472 | Robust Quantitative T1rho imaging | |
| Huimin Zhang1, Baiyan Jiang1, Jian Hou1, Queenie Chan2, and Weitian Chen1 | ||
1Imaging and Interventional Radiology, The Chinese University of Hong Kong, Sha Tin, Hong Kong, 2Philips Healthcare, Hong Kong, Hong Kong |
||
T1rho is a valuable biomarker to probe macromolecular components in tissue. However, conventional T1rho quantification techniques are susceptible to B1 RF and B0 field inhomogeneities, which cause failure of spin-lock and signal oscillation. Adiabatic pulses have been used before and after spin-lock for simultaneous B1 RF and B0 field inhomogeneities compensation and have achieved robust spin-lock, but it does not remove the effect of field inhomogeneities to the actual T1rho value. Therefore, robust T1rho quantification still remains a problem. In this work, we utilized AC-iTIP and combined it with a proposed correction method to address this problem. |
| 1473 | R1ρ Dispersion imaging in human skeletal muscle at 3 Tesla | |
| Fatemeh Adelnia1, Zhongliang Zu1,2, Feng Wang1,2, Kevin D Harkins3, and John C Gore1,2,3,4,5 | ||
1Vanderbilt University Institute of Imaging Science, Nashville, TN, United States, 2Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, United States, 3Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, United States, 4Department of Physics and Astronomy, Vanderbilt University, Nashville, TN, United States, 5Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, United States |
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R1ρ dispersion over a range of weak locking fields has the potential to reveal information on microvascular geometry and density such as microvascular spacing. This work presents in-vivo results supporting the application of R1ρ dispersion at low locking fields to the measurement of microvascular sizes and spacings in skeletal muscle. We present model fit parameters from measurements of R1ρ dispersion of human skeletal muscle that is close to ex-vivo data. |
| 1474 | Highly accelerated T1ρ imaging using kernel-based low-rank compressed sensing reconstruction in knees with and without osteoarthritis | |
| Jeehun Kim1,2, Chaoyi Zhang3, Mingrui Yang1, Hongyu Li3, Mei Li1, Richard Lartey1, Leslie Ying3,4, and Xiaojuan Li1 | ||
1Department of Biomedical Engineering, Program of Advanced Musculoskeletal Imaging (PAMI), Cleveland Clinic, Cleveland, OH, United States, 2Department of Electrical Engineering, Case Western Reserve University, Cleveland, OH, United States, 3Electrical Engineering, University at Buffalo, State University of New York, Buffalo, NY, United States, 4Biomedical Engineering, University at Buffalo, State University of New York, Buffalo, NY, United States |
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The T1ρ imaging is a promising biomarker for early diagnosis of osteoarthritis, but the application of the method is hindered by its long scan time. In this work, a novel compressed sensing algorithm based on kernel-based low-rank was proposed. The algorithm was evaluated with numerical simulation and volunteer scans, where the volunteers with and without osteoarthritis was scanned with prospective downsampling to evaluate the algorithm performance regarding the presence of pathology. |
| 1475 | Reproducible high-resolution T1ρ maps of the brain in under seven minutes using compressed sensing | |
| Gabriele Bonanno1,2,3, Tom Hilbert4,5,6, Patrick Leibig7, and Tobias Kober4,5,6 | ||
1Advanced Clinical Imaging Technology,Siemens Healthcare AG, Bern, Switzerland, 2Translational Imaging Center, sitem-insel AG, Bern, Switzerland, 3Departments of Radiology and Biomedical Research, University of Bern, Bern, Switzerland, 4Advanced Clinical Imaging Technology, Siemens Healthcare AG, Lausanne, Switzerland, 5Department of Radiology, University Hospital (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland, 6LTS5, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland, 7Siemens Healthcare GmbH, Erlangen, Germany |
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Relaxometry in the rotating frame can give unique insights into low frequency biological processes, and therefore may be a valuable quantitative MRI method for clinical research of neurodegenerative diseases. However, T1ρ maps require long scan times for whole-brain coverage with high isotropic resolution. We present a T1ρ mapping method based on an accelerated spiral-phyllotaxis 3D Cartesian gradient echo scan with compressed sensing reconstruction that allows for <7-min acquisition time and provides maps directly at the scanner to facilitate a fast workflow for clinical applications. Our method also demonstrated excellent repeatability and reproducibility. |
| 1476 | Correction of errors in estimates of T1ρ at low spin-lock amplitudes in the presence of B0 and B1 inhomogeneities | |
| Zhongliang Zu1, Fatemeh Adelnia1, Kevin Harkins1, Feng Wang1, and John Gore1 | ||
1Vanderbilt University Medical Center, Nashville, TN, United States |
||
Spin-lock imaging at low locking amplitudes are sensitive to the effects of water diffusion in intrinsic gradients and may provide information on tissue microvasculature. However, although composite pulse preparations have been used to reduce artifacts due to B0 and B1 inhomogeneities, there are still residual errors. Here, we analyze the source of these errors and developed an approximate theoretical analysis to correct these errors. Simulations and experiments on a healthy human subject show that these errors are mainly due to B0 shifts, and can be reduced by this correction approach when the B0 shift is relatively small compared with w1. |
| 1477 | High Resolution Adiabatic T1ρ Mapping Using 3D MAPSS Sequence at 3T | |
| Can Wu1,2 and Qi Peng3 | ||
1Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY, United States, 2Philips Healthcare, Andover, MA, United States, 3Department of Radiology, Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, NY, United States |
||
The 3D MAPSS T1ρ sequence provides fast and accurate T1ρ quantification with high spatial fidelity using RF phase cycling and variable flip angle in a MP-GRE sequence. However, the conventional 3D MAPSS sequence uses continuous-wave RF pulses for spin locking and is thus sensitive to B0 and B1 field inhomogeneities. In this study, a 3D MAPSS T1ρ sequence with adiabatic RF pulses was implemented and was shown to be less sensitive to B0 frequency offset on phantom compared to conventional 3D MAPSS T1ρ mapping. It was also successfully applied to high-resolution 3D T1ρ mapping of knee cartilage and brain tissue. |
| 1478 | Comprehensive T1ρ Measurement of in vivo Lumbar Intervertebral Discs using a 3D Adiabatic T1ρ Prepared UTE (UTE-Adiab-T1ρ) Sequence | |
| Zhao Wei1,2,3, Alecio F. Lombardi1, Zubiad Ibrahim1, Mohammadamin Cheraghi1, Koihi Masuda4, Jiang Du1, Eric Y. Chang1,5, Graeme M. Bydder1, Wenhui Yang2,3, and Ya-Jun Ma1 | ||
1Department of Radiology, UC San Diego, San Diego, CA, United States, 2Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing, China, 3University of Chinese Academy of Sciences, Beijing, China, 4Department of Orthopedic Surgery, UC San Diego, San Diego, CA, United States, 5Radiology Service, Veterans Affairs, San Diego Healthcare System, San Diego, CA, United States |
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To assess the feasibility of using a 3D ultrashort echo time sequence with adiabatic T1ρ preparation (UTE-Adiab-T1ρ) to map the T1ρ of entire lumbar intervertebral discs (IVDs), 17 human subjects’ lumbar spines were scanned. Correlations between T1ρ values of all of the components of the IVD and disc degeneration grades and subjects' ages were calculated. T1ρ differences between subjects with and without low back pain were also assessed. The study showed that the UTE-Adiab-T1ρ sequence can measure T1ρ values of the whole IVD. These may be useful for assessment of IVD degeneration. |
| 1479 | Quantitative inhomogeneous MT with Cramer Rao lower bound optimized protocol to distinguish tissue from donors with/without Multiple Sclerosis | |
| Gopal Varma1, Aaron K Grant1, Olivier M Girard2, Guillaume Duhamel2, and David C Alsop1 | ||
1Radiology, Division of MR Research, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States, 2CNRS, CRMBM, Aix-Marseille Univ, Marseille, France |
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Inhomogeneous magnetization transfer (ihMT) is predominantly associated with myelin imaging and shows promise in detection and monitoring myelin related disorders, including multiple sclerosis (MS). Extraction of quantitative parameters from ihMT data (qihMT) would ideally provide information independent of the ihMT sequence. We used Cramer Rao lower bound analysis to develop an optimized acquisition protocol for qihMT and simulations to test the fidelity of the protocol. Preliminary application to central nervous system samples showed differences in free pool longitudinal relaxation rate R1a, bound pool transverse relaxation time T2b, and dipolar relaxation time T1d between specimens from donors with and without MS. |
| 1480 | Fast 3D steady state inhomogeneous magnetization transfer imaging with Segmented Spoiled Gradient Echo - Echo Planar Imaging. | |
| Masanori Ozaki1 and Masao Yui1 | ||
1Research and Development Center, Canon Medical Systems Corporation, Kawasaki, Japan |
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Inhomogeneous magnetization transfer is a promising technique to provide high sensitivity and specificity of detecting myelinated content in tissue. 3D steady-state ihMT imaging with 3D segmented Spoiled Gradient Echo (SPGR) sequence can provide myelin information of the whole brain within 5-10min of acquisition time. In this work, we demonstrate 3D steady-state ihMT imaging with a 3D segmented Spoiled Gradient Echo - Echo Planar Imaging (SPGR-EPI) sequence instead of 3D segmented SPGR to reduce acquisition time. We successfully reduced approximately 30% of the acquisition time for 3D steady-state ihMT imaging by applying 3D Segmented SPGR-EPI compared to 3D segmented SPGR. |
| 1481 | Accelerated Fitting for Quantitative Magnetization Transfer in Glioblastoma Multiforme Patients with Uncertainty using Deep Learning | |
| Matt Hemsley1,2, Rachel W Chan2, Liam Lawrence1,2, Sten Myrehaug3,4, Arjun Sahgal2,3,4, and Angus Z Lau1,2 | ||
1Medical Biophysics, University of Toronto, Toronto, ON, Canada, 2Department of Physical Sciences, Sunnybrook Research Institute, Toronto, ON, Canada, 3Department of Radiation Oncology, Sunnybrook Health Sciences Centre, Toronto, ON, Canada, 4Department of Radiation Oncology, University of Toronto, Toronto, ON, Canada |
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qMT has been suggested as a biomarker in Glioblastoma patients. However, reconstruction involves a computationally expensive fitting procedure involving the Bloch-McConnell equations. In this work, the use of neural networks was investigated to perform the fit and to compute uncertainty heatmaps to identify regions of potential error. The dataset consisted of 164 scans from N=41 glioblastoma patients (33=training, 8=testing). Models were evaluated using MAE and correlation in the whole-head volumes and specific ROIs. The model output agreed with a conventional curve-fitting algorithm (r=0.93, and <1% error) with speed up factors of 240000x. Uncertainty predictions were correlated with prediction error (r=0.59). |
| 1482 | Super-Lorentzians and MT Asymmetries and Dipolar Order – Oh My! | |
| Scott D. Swanson1 | ||
1Department of Radiology, University of Michigan, Ann Arbor, MI, United States |
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MT studies of model systems disentangle effects of MT asymmetry and dipolar oder. Choice of lipid materials controls amplitude of ihMT. These studies help outline the physical mechanisms of MT and provide guidance for design of MT, MTA, and ihMT phantoms. |
| 1483 | Toward more specific imaging of fibrosis: The z-spectrum of collagen | |
| Nabeelah Jinnah1, Olivier Mougin1, Penny Gowland1, Caroline Hoad1, Gordon Moran1, Andrew Carradus1, and Hannah Williams1 | ||
1University of Nottingham, Nottingham, United Kingdom |
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We have characterized the z-spectrum of collagen at 3T and 7T. We found two peaks +1.9 ppm and at +3.5 ppm and fitting to the Bloch McConnell equations yielded pool sizes that increased monotonically with concentration. |
| 1484 | Differential diagnosis rectal cancer with and without lymph node metastasis using amide proton transfer-weighted imaging and T1 map | |
| Anliang Chen1, Ailian Liu1, Jiazheng Wang2, Zhiwei Shen2, Deshuo Dong1, Wan Dong1, Yuhui Liu1, Qingwei Song1, and Renwang Pu1 | ||
1Radiology, The First Affiliated Hospital of Dalian Medical University, Dalian, China, 2Philips Healthcare, Beijing, China |
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Amide proton transfer-weighted (APTw) imaging can be used to assess changes of intracellular protein concentration and the pH value. Non-invasive visualization and quantification of tissue composition could be detected by T1 map. In this study, we aim to explore the value in difference of rectal cancer with and without lymph node metastasis using APTw imaging combined with T1 map. High diagnostic efficacy (AUC: 0.891; sensitivity: 81.8%; specificity: 100.0%) was achieved with combination of APT and T1 values. |
| 1485 | B0 and B1 correction anti-respectively for chemical exchange saturation transfer imaging | |
| Ying-Hua Chu1, Yi-Cheng Hsu1, and Patrick Alexander Liebig2 | ||
1MR Collaboration, Siemens Healthcare Ltd., Shanghai, China, 2Siemens Healthcare GmbH, Erlangen, Germany |
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We propose a new simultaneous B0 and B1 correction for Chemical Exchange Saturation Transfer imaging. This method undersamples the number of offsets on the B1 and B0 plane. The CEST map's mean error almost halved at the upper brain region compared with the conventional method and the minimal sampled B0/B1 correction method. The proposed method provides an efficient B0 and B1 correction and may improve the diagnostic accuracy using CEST imaging at 3T. |
| 1486 | Golden-Angle Radial CEST MR Fingerprinting with Temporal Compressed Sensing Reconstruction | |
| Ouri Cohen1 and Ricardo Otazo1 | ||
1Memorial Sloan Kettering Cancer Center, New York, NY, United States |
||
Chemical Exchange Saturation Transfer (CEST) is a novel imaging technique that is sensitive to metabolite concentrations at imaging resolutions in clinically relevant scan times. These features have generated much interest and applications of CEST in assessing disease pathologies, progression and therapeutic response are currently being explored. A quantitative framework for CEST based on MR Fingerprinting (MRF) was recently proposed using an EPI readout. Here we describe preliminary work to leverage the inherent B0 and motion robustness of radial imaging to develop a clinical golden-angle radial CEST-MRF that doesn't suffer from the classic EPI drawbacks. |
| 1487 | Improving Fidelity of Concentration Dependence in CEST- MRI using pH-insensitive Low Duty Cycle Saturation Pulse Trains | |
| Julius Chung1 and Tao Jin1 | ||
1University of Pittsburgh, Pittsburgh, PA, United States |
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Low duty cycle π-pulsed CEST is an easy to implement method for exchange rate insensitive CE-MRI measurement that is dependent on labile proton concentration. In creatine phantoms with varying pH, decreasing duty cycle of π-pulse trains decreased pH dependence. In creatine phantoms of varying concentration and varied pH, exchange dependent relaxation asymmetry of π-pulsed CEST shows stronger linear dependence on concentration at lower duty cycles than continuous wave. Low duty cycle π-pulsed CEST may be useful in studies in which a change of chemical exchange rate (e.g., pH, catalyst concentration, and temperature changes) can interfere with accurate assessment of pathology. |
| 1488 | Glutamine contribution to GluCEST at 7.0T | |
| Ravi Prakash Reddy Nanga1, Mohammad Haris2, Hari Hariharan1, and Ravinder Reddy1 | ||
1Radiology, University of Pennsylvania, Philadelphia, PA, United States, 2Research Branch, Sidra Medical and Research Center, Doha, Qatar |
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Glutamate chemical exchange saturation transfer (GluCEST) is an emerging imaging technique and in the recent years has shown promising applications in Alzheimer’s, Parkinson’s, Epilepsy, Brain tumors and Schizophrenia. Due to structural similarity of glutamine with glutamate, often there is a misconception of glutamine contribution to CEST effect of glutamate. In this study, we investigated the glutamine contribution to glutamate CEST at 3ppm offset. |
| 1489 | A comparison of recent motion-correction methods for CEST-MRI | |
| Botao Zhao1, Ying Liu1, and Xiao-Yong Zhang1 | ||
1Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, China |
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The motion in chemical exchange saturation transfer (CEST) image was overlooked in many published studies. Fortunately, several works have been reported to do motion correction for CEST processing. However, the performance of these methods has not been evaluated. The main purpose of this study is to compare the performance of these methods on motion correction for CEST imaging. We used NMSE, MCC, and UI to evaluate the performance of these methods. Our simulation and preliminary in-vivo data showed that the method of Reg2mean works the best. |
| 1490 | Sensitivity-enhanced and Shading-reduced Chemical Exchange Saturation Transfer Imaging of the Abdomen using Parallel Transmission | |
| Ruibin Liu1, Zihua Qian2, Zhe Wu3, Yi-Cheng Hsu4, Caixia Fu5, Yi Sun4, Dan Wu1, and Yi Zhang1 | ||
1Key Laboratory for Biomedical Engineering of Ministry of Education, Department of Biomedical Engineering, College of Biomedical Engineering & Instrument Science, Zhejiang University, Hangzhou, China, 2Department of Radiology, The Children’s Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China, 3Techna Institute, University Health Network, Toronto, ON, Canada, 4MR Collaboration, Siemens Healthcare Ltd., Shanghai, China, 5MR Application Development, Siemens Shenzhen Magnetic Resonance Ltd., Shenzhen, China |
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CEST imaging benefits from longer saturation duration and a higher saturation duty cycle. Dielectric shading effects occur when the RF wavelength approaches the object size. Here, we proposed a parallel-transmission-based CEST (pTx-CEST) sequence to extend the maximum saturation duration at 100% duty-cycle and mitigate shading effects. The maximum saturation duration in pTx-CEST was lengthened to 2170, 3150, and 4130ms compared to 1050ms in non-pTx-CEST at TR of 3s, 4s, and 5s, respectively, leading to a significant sensitivity enhancement. Besides, the optimal amplitude ratio and phase difference between RF channels, manifesting circular or elliptical polarization, help reduce the dielectric shading effects. |
| 1824 | The Effect of Transmit B1 Inhomogeneity on Hyperpolarized [1-13C]-Pyruvate Metabolic MR Imaging Biomarkers | |
| Collin J. Harlan1, Zhan Xu1, Christopher M. Walker1, Keith A. Michel1, Galen D. Reed 2, and James A. Bankson1,3 | ||
1Department of Imaging Physics, The University of Texas M.D. Anderson Cancer Center, Houston, TX, United States, 2GE Healthcare, Dallas, TX, United States, 3The University of Texas M.D. Anderson Cancer Center UT Health Graduate School of Biomedical Sciences, Houston, TX, United States |
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Accurate signal excitation is imperative when conducting hyperpolarized 13C MRI studies. It has been determined from previous work that greater than ±10% deviation in excitation angle can lead to significant excitation angle dependent errors in kinetic analysis of HP [1-13C] pyruvate to lactate conversion. This work was conducted to characterize the B1+ field homogeneity of a 13C volume transmit clamshell coil. Furthermore, an assessment of the impact of potential B1+ inhomogeneities on semi-quantitative and quantitative hyperpolarized metabolic MR imaging biomarkers was conducted. |
| 1825 | Simultaneous quantification of T2 and T2* by accelerated 10-echo GESE-EPIK sequence for carrageenan-phantoms and in vivo data | |
| Fabian Küppers1,2,3, Seong Dae Yun1, and N. Jon Shah1,2,4,5 | ||
1Institute of Medicine and Neuroscience 4, Forschungszentrum Juelich GmbH, Jülich, Germany, 2Institute of Medicine and Neuroscience 11, Forschungszentrum Juelich GmbH, Jülich, Germany, 3RWTH Aachen University, Aachen, Germany, 4Department of Neurology, RWTH Aachen University, Aachen, Germany, 5JARA - BRAIN - Translational Medicine, Aachen, Germany |
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Combining GE and SE signals enables quantification of several pertinent parameters making it useful in various applications. An 10-echo GESE sequence based on EPIK, known as EPI with keyhole, has been presented in our earlier work. This work employs an accelerated sequence implementation and aims to perform quantification of T2/T2* for both phantom and in vivo data. The method was configured to provide improved resolution within feasible TEs for brain scans, i.e. 1 minute. The quantified T2/T2* values were in good agreement with values from reference methods. Moreover, an SNR/tSNR analysis proves the signal and time gain from multi-shot acceleration. |
| 1826 | Highly accelerated compressed sensing chemical exchange saturation transfer | |
| Ying-Hua Chu1, Patrick Alexander Liebig2, He Wang3, and Yi-Cheng Hsu1 | ||
1MR Collaboration, Siemens Healthcare Ltd., Shanghai, China, 2Siemens Healthcare GmbH, Erlangen, Germany, 3Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, China |
||
We proposed a CEST imaging method using compressed sensing to accelerate image acquisition. Compared with the full sampled one with two averages, the compressed sensing method used only 7.6% scan time with around 0.5% error in amide proton transfer weighted (APTw) images. The whole-brain acquisition for one RF offset took only 6 seconds. This method can accelerate conventional APTw images to reduce motion artifact and make a high signal-to-noise ratio acquisition with large number offsets for Lorentzian fitting possible. |
| 1827 | In Vivo Mapping of Non-heme Iron Using Time-dependent R2* Relaxation Measured with MGRE | |
| Sohae Chung1,2, Dmitry S. Novikov1,2, Pippa Storey1,2, and Yvonne W. Lui1,2 | ||
1Center for Advanced Imaging Innovation and Research (CAI2R), Department of Radiology, New York University Grossman School of Medicine, New York, NY, United States, 2Bernard and Irene Schwartz Center for Biomedical Imaging, New York University Grossman School of Medicine, New York, NY, United States |
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Identification and quantification of imaging biomarkers sensitive to iron are important in understanding neurodegenerative disorders and aging. In this study, we introduce a microstructural parameter, $$$\delta\Omega^{2}$$$, the Larmor frequency variance, measured from the curvature in the logarithm of the signal from a 3D multiecho gradient echo sequence. Non-monoexponential relaxation originates from magnetic field perturbations due to the presence of mesoscopic susceptibility sources such as cellular-level iron. Our results in 26 healthy subjects show a strong linear correlation between $$$\delta\Omega^{2}$$$ and published values for iron concentration in deep gray matter regions, suggesting its potential as an imaging biomarker for iron. |
| 1828 | 3D Silent Parameter Mapping: Further refinements & quantitative assessment | |
| Florian Wiesinger1,2, Graeme McKinnon3, Sandeep Kaushik1, Ana Beatriz Solana1, Emil Ljungberg2, Mika Vogel1, Naoyuki Takei4, Rolf Schulte1, Carolin Pirkl1, Cristina Cozzini1, Laura Nuñez-Gonzalez5, Juan A. Hernandez Tamames5, and Mathias Engström6 | ||
1GE Healthcare, Munich, Germany, 2IoPPN, Department of Neuroimaging, King's College London, London, United Kingdom, 3GE Healthcare, Waukesha, WI, United States, 4GE Healthcare, Hino, Japan, 5Erasmus MC, Rotterdam, Netherlands, 6GE Healthcare, Stockholm, Sweden |
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Here we present further improvements of a 3D Silent Parameter Mapping method in terms of Deep Learning image reconstruction and synthetic CT image conversion. We evaluated its quantitative accuracy using the NIST/ISMRM phantom and illustrate healthy volunteer results at 1.5T and 3T. |
| 1829 | The “Prequence” Concept: Toward Significantly Faster Clinical MRI Exams | |
| Vincent Schmithorst1, Ashok Panigrahy2, and Rafael Ceschin3 | ||
1Radiology, University of Pittsburgh, Pittsburgh, PA, United States, 2University of Pittsburgh, Pittsburgh, PA, United States, 3Bioinformatics, University of Pittsburgh, Pittsburgh, PA, United States |
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Availability of clinical fMRI would be much improved via reduction of clinical exam times. A major factor in length of exam times is that typical MRI pulse sequences are optimized for a single image contrast (T1, T2, FLAIR, etc.) necessitating multiple pulse sequences each with significant “dead time” to acquire all desired contrasts for a given protocol. We here propose instead the time-efficient “prequence” (protocol sequence) concept which aims at acquisition of all desired contrasts in one or only a few sequences with minimal dead time. Preliminary proof-of-concept is demonstrated via a simultaneous T1/T2 contrast whole-brain neuro acquisition. |
| 1830 | Balanced SSFP Parameter Estimation by Fitting Multi-TR Ellipses | |
| Nicholas McKibben1, Michael Mendoza2, Neal K Bangerter2, and Michael N Hoff3 | ||
1University of Utah, Salt Lake City, UT, United States, 2Department of Bioenginnering, Imperial College London, London, United Kingdom, 3Deptartment of Radiology, University of Washington, Seattle, WA, United States |
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Multiple linearly phase-cycled, multiple-TR bSSFP can be used to effectively estimate off-resonance and condition input to the PLANET algorithm to make it robust to noise and lack of available phase-cycled images. We provide methods of estimating off-resonance given 6 or 8 phase-cycles distributed across multiple-TR acquisitions. Using the elliptical signal model, it is shown that similar ellipse shape at high flip angles allow rotated ellipses to be superimposed, leading to the construction of "virtual" ellipses. Virtual ellipses are shown to be robust to noise and perform well in simulation and phantom studies. |
| 1831 | Pyruvate Infusion Rates for Hyperpolarized Metabolite Imaging of Human Heart | |
| Jeffry R. Alger1,2,3,4, Jae Mo Park1, Junjie Ma1, Mahitha Roy1, Crystal Harrison1, James Ratnakar1, Albert Chen5, Galen Reed6, A. Dean Sherry1,7, Vlad Zaha1, and Craig R. Malloy1,8 | ||
1Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, United States, 2Neurology, University of California, Los Angeles, Los Angeles, CA, United States, 3NeuroSpectroScopics LLC, Sherman Oaks, CA, United States, 4Hura Imaging Inc, Los Angeles, CA, United States, 5GE Healthcare, Toronto, ON, Canada, 6GE Healthcare, Dallas, TX, United States, 7Chemistry, University of Texas at Dallas, Richardson, TX, United States, 8Cardiology, Veterans Affairs North Texas Healthcare System, Dallas, TX, United States |
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MRI/MRS metabolic tracing in human heart with hyperpolarized 13C-enriched pyruvate is feasible, but there remains a need to define the optimal infusion timing that accommodates both short polarization lifetime and subject comfort. Typical studies have used a 5.0 cm3/sec pyruvate infusion rate. We hypothesized that slower infusion is feasible because of the in vitro versus intravascular T1 difference and because vascular properties limit the rate of pyruvate delivery from the infusion site to the heart. Vascular dynamic simulations and preliminary human investigations suggest that a 2.0 cm3/sec pyruvate infusion rate be effectively used. |
| 1832 | Dipole inversion by recurrent inference for quantitative susceptibility mapping | |
| Samy Abo Seada1, Emanoel Ribeiro Sabidussi1, Sebastian Weingärtner2, Dirk H. J. Poot1, and Juan Antonio Hernandez-Tamames1 | ||
1Department of Radiology and Nuclear Medicine, Erasmus MC, Rotterdam, Netherlands, 2Department of Imaging Physics, TU Delft, Delft, Netherlands |
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QSM dipole inversion remains a challenge and recent machine learning approaches have not incorporated the known forward model directly. We propose using recurrent inference machines (RIM), a type of unrolled optimization technique, which are proposed for solving iterative inverse problems specifically. RIMs enable incorporating the forward dipole convolution directly in the learning process. Simulated data was used for training. The QSM reconstruction was tested on simulated data and healthy subject data acquired at 3T. |
| 1833 | Improvements from local B0 shimming for QSM at 7 Tesla | |
| Sina Straub1, Mark E. Ladd1,2, Paul Chang3, and Sahar Nassirpour3 | ||
1Division of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany, 2Faculty of Physics and Astronomy, Faculty of Medicine, University of Heidelberg, Heidelberg, Germany, 3MR Shim GmbH, Reutlingen, Germany |
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A 14-channel local array of shim coils was used to improve B0 homogeneity and reduce artifacts in quantitative susceptibility mapping at 7T. Using the local array of shim coils in addition to the standard 2nd order spherical harmonic shims, the B0 shim quality was improved by an average of 16% across all volunteers. Local inhomogeneities were significantly reduced and could be correlated to reduced artifacts in QSM. |
| 1834 | Development of a simulation method to evaluate T2* shortening due to susceptibility of fat in the liver using the finite element method | |
| Daiki Tamada1, Noriaki Nagata1, Ryoichi Kose2, Katsumi Kose2, Utaroh Motosugi3, and Hiroshi Onishi1 | ||
1Department of Radiology, University of Yamanashi, Chuo, Japan, 2MRIsimulations Inc., Tokyo, Japan, 3Department of Radiology, Kofu-Kyoritsu Hospital, Kofu, Japan |
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A method to simulate T2* shortening by the susceptibility of fat in the liver using FEM and simple modeling was developed. The model consisting of water and lipid droplets (LD) placed randomly. Simulation and in vivo studies indicated the feasibility of our method. The results suggested the microscopic field inhomogeneity by LDs leads to non-neglectable T2* decay. Besides, the result of in vivo study was fairly agreed with the simulation. |
| 1835 | Software for T1ρ Mapping in the Knee: Addressing the Critical Role of Motion Correction | |
| Artem Mikheev1, Louisa Bokacheva1, Azadeh Sharafi1, Ravinder Regatte1, and Henry Rusinek1 | ||
1Department of Radiology, New York University School of Medicine, New York, NY, United States |
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T1ρ mapping enables detecting early changes in the knee cartilage associated with osteoarthritis. Reproducible T1ρ measurements are challenging because of the motion artifacts arising from a long acquisition time of images at multiple spin-lock times. We implemented a new elastic motion correction method and applied it to T1ρ-weighted acquisitions in 20 subjects with normal knees and early osteoarthritis. The T1ρ voxel maps in articular cartilage generated from motion-corrected images showed significantly lower variability compared to maps derived from uncorrected images. The finding underscores the importance of motion correction in T1ρ mapping of the knee. |
| 1836 | Early results from a patient study aimed at testing a quantitative and synthetic brain MRI method, for abbreviated neuro protocols | |
| Cheng-Chieh Cheng1, Jeffrey P. Guenette2, and Bruno Madore2 | ||
1Computer Science and Engineering, National Sun Yat-sen University, Kaohsiung, Taiwan, 2Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States |
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We developed a quantitative and synthetic MRI method capable of generating the most-commonly encountered contrasts in neuro protocols, along with quantitative parameter maps, with full brain coverage and 1-mm isotropic resolution, from only about 5 min of scanning. The eventual goal is for this sequence and associated processing to play a role in abbreviated neuro protocols. Promising results were obtained in healthy volunteers and we recently embarked on a larger patient study. After a few months of delay, largely associated with the pandemic, patient recruitment has started, and preliminary results are shown here. |
| 1837 | Shearlet-based susceptibility map reconstruction with additional TGV-regularization | |
| Janis Stiegeler1,2 and Sina Straub1 | ||
1Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany, 2Faculty of Physics and Astronomy, University of Heidelberg, Heidelberg, Germany |
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The 2016 Reconstruction Challenge urged the need of QSM algorithms which minimize several classical image quality measures relatively to a ground truth, but also achieve an acceptable human image perception by avoiding oversmoothing effects. A multicale shearlet system was used together with a total generalized variation (TGV) term to regularize the susceptibility-phase convolution problem. The results show that these regularizers are useful to obtain quantitative susceptibility maps which are rich in detail and simultaneously can achieve top five results in the ranking of the 2016 Reconstruction Challenge regarding all classical image quality measures used in this challenge. |
| 1838 | New method of estimating static field inhomogeneity for MR susceptometry-based oximetry | |
| Alexander M Barclay1, Michael C Langham1, and Felix W Wehrli1 | ||
1Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States |
||
Large vein blood oxygenation level can be estimated by magnetic susceptibility-based oximetry. Calculation of the local field shift between intravascular blood and surrounding tissue using measurement of signal phase is done with field mapping. Measurement is confounded by background static field inhomogeneity. Correction by either high-pass filtering to remove spatially slow-varying inhomogeneity, or polynomial fitting of inhomogeneity to be subtracted-out require measuring reference tissue phase, imparting bias and constraining signal-to-noise ratio considerations to tissue, not lumen. An objective approach based on inhomogeneity estimation using a smoothness criterion is proposed. Tissue phase is eliminated, allowing measurement of intravascular phase alone. |
| 1839 | A Deep Learning Approach to QSM Background Field Removal: Simulating Realistic Training Data Using a Reference Scan Ground Truth and Deformations | |
| Oriana Vanesa Arsenov1, Karin Shmueli1, and Anita Karsa1 | ||
1Medical Physics and Biomedical Engineering, University College London, London, United Kingdom |
||
Current techniques for background field removal (BGFR), essential for quantitative susceptibility mapping, leave residual background fields and inaccuracies near air-tissue interfaces. We propose a new deep learning method aiming for robust brain BGFR: we trained a 3D U-net with realistic simulated and in-vivo data augmented with spatial deformations. The network trained on synthetic data predicts accurate local fields when tested on synthetic data, (median RMSE = 49.5%), but is less accurate when tested on in-vivo data. The network trained and tested on in-vivo data performs better, suggesting our synthetic set did not fully capture the complexity found in vivo. |
| 1840 | Measuring inhomogeneous MT (ihMT) in human brain by multi-parameter mapping (MPM) | |
| Gunther Helms1,2, Lenka Vaculčiaková2, Kerrin J. Pine2, Harald E. Moeller3, and Nikolaus Weiskopf2,4 | ||
1Medical Radiation Physics, Clinical Sciences Lund, Lund University, Lund, Sweden, 2Neurophysics, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany, 3NMR Methods & Development Group, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany, 4Felix Bloch Institute for Solid State Physics, Leipzig University, Leipzig, Germany |
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Inhomogenous Magnetization Transfer (ihMT), the differential response to irradiation at single and dual frequency offsets, is sensitive to myelination. Quantification of ihMT in terms of MT saturation (MTsat), the percent reduction of Mz, corrects for underlying T1 and B1+ and allows comparing different implementations to optimize multi-parameter mapping (MPM) protocols. ihMTsat in white matter is roughly one twentieth of MTsat, merely 0.2 p.u. at 5kHz and 100% SAR at 3T. Noise propagation demands acquisition at 1.5mm resolution, large-array coils, and smaller offsets than suggested previously. Inverse MT ratios are highly correlated to ihMTs but obscure the true effect size. |
| 1841 | Reliable estimation of the MRI-visible effective axon radius using light microscopy: the need for large field-of-views | |
| Laurin Mordhorst1, Maria Morozova2,3, Sebastian Papazoglou1, Björn Fricke1, Jan Malte Oeschger1, Henriette Rusch3, Carsten Jäger2, Markus Morawski2,3, Nikolaus Weiskopf2,4, and Siawoosh Mohammadi1,2 | ||
1Institute of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany, 2Department of Neurophysics, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany, 3Paul Flechsig Institute of Brain Research, University of Leipzig, Leipzig, Germany, 4Felix Bloch Institute for Solid State Physics, Faculty of Physics and Earth Sciences, Leipzig, Germany |
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MRI-based models enable non-invasive characterization of brain microstructure, e.g. the effective axon radius ($$$r_{\text{eff}}$$$). Often, these models were validated by small-field-of-view microscopy (sFoVM) images (~10³ axons). As $$$r_{\text{eff}}$$$ is dominated by large, sparsely occurring axons, sFoVM-based estimations may miss large axons and underestimate $$$r_{\text{eff}}$$$. We employed an in-house developed pipeline to estimate $$$r_{\text{eff}}$$$ on large-scale light microscopy (lsLM) sections with similar spatial extent as the voxel sizes in human MRI systems. Taking lsLM as a baseline, we showed that sFoVM is an unsuitable reference for $$$r_{\text{eff}}$$$ and verified the potential of $$$r_{\text{eff}}$$$ to capture relevant spatial, anatomical variation. |
| 1842 | Simultaneous Quantification of Mean Intracellular Water Lifetime and Cell Size Using Temporal Diffusion Spectroscopy | |
| xiaoyu jiang1, sean p devan1, john c. gore1, and junzhong xu1 | ||
1Vanderbilt University Institute of Imaging Science, nashville, TN, United States |
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There is an increasing interest in characterizing tissue microstructure using multi-compartment diffusion MRI models involving multiple b values and diffusion times ($$$t_{diff}$$$s). However, previous models usually ignore water exchange between intra- and extracellular compartments, which limits the accuracy of the fitted model parameters and potentially their interpretation as indicators of disease progression or treatment response. Here, we propose a simplified biophysical model of solid tissues that allows derivation of the mean intracellular water lifetime ($$$\tau_{i}$$$) and other microstructural parameters (e.g., cell size d) simultaneously from the $$$t_{diff}$$$ dependence of diffusion MRI signals. |
| 1843 | Metabolic Effects of Deferiprone on Triple Negative Breast Cancer | |
| Paola Porcari1, Ellen Ackerstaff1, H. Carl Lekaye1, and Jason A. Koutcher1,2,3,4 | ||
1Medical Physics, Memorial Sloan Kettering Cancer Centre, New York, NY, United States, 2Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, United States, 3Molecular Pharmacology Program, Memorial Sloan Kettering Cancer Center, New York, NY, United States, 4Weill Cornell Medical College, Cornell University, New York, NY, United States |
||
Triple-negative breast cancer (TNBC) metastasizes and is currently associated with poor prognosis and lack of effective targeted therapies. We are studying the potential of Deferiprone, an intracellular iron chelator clinically used for non-cancer-related diseases, to improve the chemotherapeutic treatment response in TNBC by altering cellular iron-dependent proliferation and metabolism. Here, cellular and energy metabolism changes in response to Deferiprone were assayed in live TNBC cells by multi-nuclear MRS in our MR-compatible bioreactor. Metabolic changes in a human TNBC cell line are compared to previous findings in murine TNBC cells. |
| 3557 | Convolutional Neural Networks for Super-resolution of Hyperpolarized 129Xe MR Images of the Lung | |
| Junlan Lu1, Suphachart Leewiwatwong2, David Mummy3, Elianna Bier2, and Bastiaan Driehuys3 | ||
1Medical Physics, Duke University, Durham, NC, United States, 2Biomedical Engineering, Duke University, Durham, NC, United States, 3Radiology, Duke University, Durham, NC, United States |
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Although hyperpolarized 129Xe gas exchange MRI enables imaging ventilation, barrier, and RBC components in a single breath-hold, the necessary under-sampling imposed by limited imaging time constrains image resolution. Therefore, it is common to acquire an additional dedicated ventilation scan, which increases cost and imaging time. Instead, we demonstrate that deep convolutional neural networks with template-based augmentation can be trained to transform under-sampled low-resolution 129Xe ventilation images to a level of detail comparable to that of a dedicated ventilation scan. We evaluate the performance of multiple super-resolution models based on signal-to-noise ratio and structural similarity. |
| 3558 | Optimizing Acquisition and Analysis for Diffusion Weighted Hyperpolarized 129Xe MRI of Pediatric and Adult Lungs | |
| Abdullah S. Bdaiwi1,2, Peter J. Nedbalski1, Md M. Hossain3, Matthew M. Willmering1, Laura L. Walkup1,2,4, Hui Wang5, Robert P. Thomen1, Kai Ruppert1, Jason C. Woods1,4,6, and Zackary I. Cleveland1,2,4,6 | ||
1Center for Pulmonary Imaging Research, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States, 2Biomedical Engineering Department, University of Cincinnati, Cincinnati, OH, United States, 3Division of Biostatistics and Epidemiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States, 4Division of Pulmonary Medicine, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, United States, 5Philips, Cincinnati, OH, United States, 6Department of Pediatrics, University of Cincinnati, Cincinnati, OH, United States |
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Hyperpolarized (HP) 129Xe MRI can non-invasively quantify lung microstructure through measuring the gas-phase apparent diffusion coefficient (ADC), providing insights into disease pathophysiology—e.g., emphysema severity. To maximize the utility of this method, we developed an analytical model, based on HP-specific Bloch equations and error propagation, to optimize ADC measurements in terms of acquisition parameters (b-value, flip angle, phase encodes, etc.) and the ADC itself and validated this model via Monte Carlo and phantom studies. Finally, a lower bound on the expected 129Xe ADC was obtained by measuring ADC as a function of age in human subjects as young as six years. |
| 3559 | Assessment of dynamic airflow heterogeneity after bronchodilator in asthma using hyperpolarized helium-3 MRI | |
| Mu He1, Lindsay A. Somerville1, Nicolas J. Tustison1, James Patrie1, Jaime F. Mata1, Joanne M. Cassani2, Roselove Nunoo-Asare1, Alan Ropp1, Wilson G. Miller1, Yun Michael Shim1, Talissa A. Altes2, John P. Mulger1, and Eduard E. de Lange1 | ||
1University of Virginia, Charlottesville, VA, United States, 2University of Missouri, Columbia, MO, United States |
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With hyperpolarized helium-3 (3He) MRI regional differences in airflow heterogeneity can be assessed. In this study, we used weighted entropy to evaluate dynamic ventilation heterogeneity in asthmatics. Serial 3He/1H scans were co-registered and normalized for comparison. Weighted entropy was calculated based on entropy and Ventilation defect percentage (VDP) values derived from normalized 3He scans. Lobar analysis was performed to identify lobar weighted entropy. We found that asthmatics have more heterogeneous ventilation distribution in the lower lobes at baseline. Variable airflow heterogeneity changes were observed globally in asthmatics, with the most significant bronchodilator response in the left lung. |
| 3560 | Comparison of 3D convolutional neural networks and loss functions for ventilated lung segmentation using multi-nuclear hyperpolarized gas MRI | |
| Joshua R Astley1,2, Alberto M Biancardi1, Paul J Hughes1, Laurie J Smith1, Helen Marshall1, Guilhem J Collier1, James Eaden1, Nicholas D Weatherley1, Jim M Wild1, and Bilal A Tahir1,2 | ||
1POLARIS, University of Sheffield, Sheffield, United Kingdom, 2Oncology and Metabolism, University of Sheffield, Sheffield, United Kingdom |
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Deep learning has shown great promise for numerous medical image segmentation tasks, including delineation of ventilated lung volumes from hyperpolarized gas MRI. We previously demonstrated the utility of a VNet convolutional neural network (CNN), trained on a combination of 3He and 129Xe scans, in producing accurate segmentations that outperform conventional methods. In this work, we compared the performance of several 3D CNNs and loss functions for segmentation of ventilated lungs on a significantly larger and more diverse multi-nuclear hyperpolarised gas MRI dataset using several training strategies. We observe that the UNet CNN provides the best performing model for our dataset. |
| 3561 | Hyperpolarized 3He MRI ADC and Ventilation Features Predict Rapidly Worsening Emphysema Using Machine-learning | |
| Maksym Sharma1, Alexander M Matheson1, David G McCormack2, David A Palma1,3, and Grace Parraga1,2,3 | ||
1Medical Biophysics, Western University, London, ON, Canada, 2Division of Respirology, Department of Medicine, Western University, London, ON, Canada, 3Department of Oncology, Western University, London, ON, Canada |
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Pulmonary hyperpolarized 3He MRI provides a way to measure lung ventilation heterogeneity in patients with COPD, including terminal airspace enlargement or emphysema that is typically quantified using CT densitometry. Unfortunately, MRI-derived biomarkers of emphysema progression remain unconfirmed, and also likely because of radiation dose considerations, CT follow-up of emphysema is rarely performed, and hence its longitudinal progression is not well-understood. Here we developed a machine-learning pipeline that identified hyperpolarized 3He MRI texture features that independently and uniquely correlated and predicted rapidly-worsening emphysema nearly 3 years later, measured as CT RA950, using a Decision Tree algorithm that achieved 82% prediction accuracy. |
| 3562 | Imaging Gas-Exchange Lung Function using Density-Weighted MRSI and Hyperpolarised 129Xe Gas | |
| Rolf F Schulte1, Guilhem J Collier2, James Ball2, Graham Norquay2, Madhwesha Rao2, and Jim M Wild2 | ||
1GE Healthcare, Munich, Germany, 2POLARIS, Department of Infection Immunity & Cardiovascular Disease, University of Sheffield, Sheffield, United Kingdom |
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3D density-weighted MRSI in combination with a frequency-tailored RF excitation pulse was designed, implemented and used to detect xenon gas in the lungs and xenon dissolved in lung tissue and blood. These images were used to calculate quantitative ratio maps of tissue-to-gas, blood-to-gas, and blood-to-tissue with good SNR. |
| 3563 | A 129Xe/1H Switched Frequency High Pass Birdcage Coil for Hyperpolarized 129Xe Gas Lung Imaging in Neonates at 1.5 T | |
| Ronald Pratt1, Randy Giaquinto1, Wolfgang Loew1, Christopher Ireland1, Neil Stewart2,3, Nara Higano2, Jason Woods2, and Charles Dumoulin1 | ||
1Imaging Research Center/Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States, 2Center for Pulmonary Imaging Research/Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States, 3POLARIS, Imaging Sciences, Dept of Infection, Immunity & Cardiovascular Disease, University of Sheffield, Sheffield, United Kingdom |
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Production of hyperpolarized 129Xe gas has opened new frontiers for imaging lung anatomy and function using MRI. Our institution has the goal of using hyperpolarized 129Xe gas for MR imaging of neonatal lungs at 1.5 T. To realize this goal, it is essential that the RF coil used for imaging operate at both the 129Xe and 1H frequencies. This report provides fabrication details of a novel 129Xe/1H switched frequency transmit/receive 16 rung high-pass birdcage RF coil. Images collected with hyperpolarized 129Xe gas and water in phantoms demonstrate that the coil provides excellent image quality at both frequencies. |
| 3564 | Temporal correlation of alveolar-capillary 129Xe signal dynamics with the cardiac cycle | |
| Graham Norquay1, Guilhem J Collier1, and Jim M Wild1 | ||
1Infection, Immunity and Cardiovascular Disease, University of Sheffield, Sheffield, United Kingdom |
||
Global 129Xe MRS was acquired in the lungs synchronously with an ECG recording to enable association of dissolved-phase 129Xe signal dynamics with the cardiac cycle. Time-domain Voigt fitting was used to calculate resonance parameters corresponding to 129Xe in red blood cells and tissue/blood plasma in the lungs. Positive and negative signal changes of 129Xe in the blood were found to be associated with ventricular systole and diastole in a healthy volunteer. |
| 3565 | Feasibility of Xenon Polarization Transfer Contrast Imaging using Continuous RF Irradiation | |
| Faraz Amzajerdian1, Tahmina Achekzai1, Luis Loza1, Hooman Hamedani1, Yi Xin1, Harilla Profka1, Ian Duncan1, Stephen Kadlecek1, Kai Ruppert1, and Rahim Rizi1 | ||
1University of Pennsylvania, Philadelphia, PA, United States |
||
Xenon-polarization Transfer Contrast (XTC) imaging is a powerful technique for quantifying exchange rates between gas- and dissolved-phase xenon compartments and involves a series of radiofrequency (RF) saturation pulses applied to the targeted dissolved-phase resonance. Although increasing the number of pulses and their spacing generates greater contrast, it also increases acquisition time. In this work, in an effort to reduce acquisition time, particularly for free-breathing imaging protocols, we explored the use of continuous RF irradiation to depolarize dissolved-phase xenon, with the goal of producing results similar to those achieved with pulsed saturations, but in a significantly shorter time period. |
| 3566 | Reproducibility Study Measuring Ventilation, Gas Exchange and Surface-to-Volume Using Hyperpolarized Xenon in Free-breathing Human Subjects | |
| Hooman Hamedani1, Stephen Kadlecek1, Faraz Amzajerdian1, Ryan Baron1, Kai Ruppert1, Ian Duncan1, Yi Xin1, Luis Loza1, Tahmina Achekzai1, Maurizio Cereda1, Kevin Ma1, David DiBardino1, and Rahim Rizi1 | ||
1University of Pennsylvania, Philadelphia, PA, United States |
||
We have previously shown the advantages of multi- over single-breath imaging of lung ventilation using HP gas MRI, and have recently introduced our approach for comprehensively assessing the lung function during a tidal breathing scheme to quantify ventilation and dissolved parameters of xenon distribution. Here, we presented the repeatability of the imaging markers in a healthy subject and a patient with severe chronic obstructive pulmonary disease (COPD) with persisting cough. We have shown that the technical back-to-back reproducibility of measuring lung function with our scheme is excellent in a healthy subject and satisfactory in a COPD subject with persisting cough. |
| 3567 | 3D isotropic spectroscopic imaging of hyperpolarized 129Xe in the human brain | |
| Madhwesha R Rao1, Guilhem J Collier1, Graham Norquay1, Rolf F Schulte2, and Jim M Wild1 | ||
1University of Sheffield, Sheffield, United Kingdom, 2GE Healthcare, Munich, Germany |
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3D isotropic images of hyperpolarized 129Xe dissolved in the brain were acquired with 1 L of inhaled xenon gas dose using a density-weighted MR spectroscopic imaging method. Images were acquired from 2 healthy male volunteers. The data was acquired with a voxel size of (2cm)3 and reconstructed to a voxel size of (0.625 cm)3 through zero filling. The isotropic voxel size and the high spectral resolution surpass previous reports using conventional 2D and echo planar spectroscopic imaging methods. |
| 3568 | Background field inhomogeneity effects on hyperpolarized 129Xe diffusion-weighted MRI at 1.5T and 3T | |
| Ho-Fung Chan1, Guilhem J Collier1, Madhwesha Rao1, and Jim M Wild1 | ||
1Infection, Immunity and Cardiovascular Disease, University of Sheffield, Sheffield, United Kingdom |
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Background field inhomogeneities due to air-tissue interface magnetic susceptibility differences in the lungs increases derived ADC measurements from 3He PGSE diffusion-weighted (DW) lung MRI at higher field strengths. To determine if the same effects are observed with 129Xe DW-MRI, 129Xe ADC and mean diffusive length scale (LmD) from healthy volunteers imaged at 1.5T and 3T were compared. A small bias towards increased 129Xe ADC (6.3%) and LmD (2.2%) values at 3T was obtained, which is smaller than the reported bias of 3He ADC (15.5%) and 3He mean chord length (10.5%), and similar to the reported 129Xe DW-MRI inter-scan repeatability differences. |
| 3569 | Detection of pulmonary abnormalities in a rabbit thoracic insufficiency syndrome model using hyperpolarized xenon-129 MRI | |
| Kai Ruppert1, Faraz Amzajerdian1, Yi Xin1, Hooman Hamedani1, Luis Loza1, Tahmina S Achekzai1, Ryan J Baron1, Ian F Duncan1, Harrilla Profka1, Yiwen Qian1, Stephen Kadlecek1, Alessandra Fusco2, Benjamin Sinder3, Patrick J Cahill3, Brian Snyder3,4, Thomas P Schaer2, and Rahim R Rizi1 | ||
1University of Pennsylvania, Philadelphia, PA, United States, 2School of Veterinary Medicine, University of Pennsylvania, Kennett Square, PA, United States, 3Children's Hospital of Philadelphia, Philadelphia, PA, United States, 4Boston Children's Hospital, Boston, MA, United States |
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Thoracic insufficiency syndrome (TIS) progresses to the development of restrictive lung disease and is commonly treated through surgical intervention. In this work, we used a rib-tether rabbit model to investigate the sensitivity of dynamic 1D simultaneous dissolved- and gas-phase hyperpolarized xenon-129 MRI imaging to pulmonary abnormalities secondary to TIS. We found asymmetric lung ventilation patterns and increases in alveolar septal wall thickness in both lungs of a rib-tethered rabbit compared to an age-matched control animal. These findings could help identify the optimal timepoint at which to conduct chest expansion surgery so as to maximize the resulting improvements in lung maturation. |
| 3570 | Modelling realistic Rb density and temperature distributions in a high throughput xenon-129 polariser | |
| James Ball1, Jim M. Wild1, and Graham Norquay1 | ||
1POLARIS, Department of Infection, Immunity and Cardiovascular Disease, The University of Sheffield, Sheffield, United Kingdom |
||
Hyperpolarised xenon-129 (129Xe) production via continuous-flow spin-exchange optical pumping often produces lower than predicted 129Xe polarisation. Frequently, thermodynamics within polariser systems is not considered, as well as spatially variant changes in rubidium (Rb) source distributions and changes in 129Xe relaxation over time. This work models realistic Rb and temperature distributions within a large-scale 129Xe-Rb polariser cell. Results show that Rb density varies significantly depending upon incident photon flux and Rb source distribution in the cell. Modelling allows estimation of the Rb presaturator length required at different gas flow rates in order to reach optimal Rb density and high 129Xe polarisation. |
| 3571 | Template-based bias field correction of Hyperpolarized 129Xe Gas Ventilation MRI | |
| Junlan Lu1, David Mummy2, Suphachart Leewiwatwong3, Elianna Bier3, and Bastiaan Driehuys2 | ||
1Medical Physics, Duke University, Durham, NC, United States, 2Radiology, Duke University, Durham, NC, United States, 3Biomedical Engineering, Duke University, Durham, NC, United States |
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Accurately correcting hyperpolarized 129Xe ventilation MRI for coil-induced bias field remains the most significant obstacle to precise, repeatable quantitative image analysis. Estimates using B1 maps from RF-depletion in radially acquired images may provide an improvement on the standard N4ITK solution, which recent works suggests may perform an overly aggressive correction. Here, we develop a template-based approach to bias field correction using B1 maps derived from multiple subjects. This paradigm is then evaluated by applying it to a set of test images reflective of a range of disease types and levels of ventilation obstruction. |
| 3572 | Performance of XTC imaging in a free-breathing mouse model exploring variable saturation delay times | |
| Tahmina Susan Achekzai1, Luis Loza2, Stephen Kadlecek2, Kai Ruppert2, Faraz Amzajerdian2, and Rahim R. Rizi1 | ||
1Radiology, University of Pennsylvania, Philadelphia, PA, United States, 2University of Pennsylvania, Philadelphia, PA, United States |
||
XTC imaging takes advantage of the exchange between gas and dissolved phase Xe to provide information on lung function, as direct dissolved phase imaging is limited in signal. In this study, we demonstrate XTC imaging in a regular and transgenic mouse model. We aim to optimize depolarization effectiveness by varying delay time and number of saturation pulses applied in the imaging scheme and demonstrate the dependence of depolarization to these parameters. |
| 3573 | Fully-automated Multi-spectral Pulmonary Registration for Hyperpolarized Noble Gas MRI Using Neural Networks | |
| Alexander M Matheson1, Rachel L Eddy1, Jonathan L MacNeil2, Marrissa J McIntosh1, and Grace M Parraga1,2 | ||
1Medical Biophysics, Robarts Research Institute, Western University, London, ON, Canada, 2School of Biomedical Engineering, Robarts Research Institute, Western University, London, ON, Canada |
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Co-registered hyperpolarized gas and proton MRI are required to calculate functional lung biomarkers using semi-automated pipelines. Automated registration between different spectral acquisitions is difficult due to differences in contrast and imaging features between different spectral images. Convolutional neural networks create abstract representations of images that may overcome these feature differences. We retrospectively pooled data sets previously registered using a semi-automated pipeline and applied random two-dimensional affine transformations and noise. Neural networks generated inverse transformation matrices from these data to correct the applied transformations. The trained network successfully corrected mis-alignment with an average error of less than one pixel. |
| 3574 | The effects of an initial depolarization pulse on the dissolved phase hyperpolarized 129Xe images | |
| Yurii Shepelytskyi1,2, Vira Grynko1,2, Tao Li3, Ayman Hassan4,5, Karl Granberg4, and Mitchell S Albert2,3,5 | ||
1Chemistry and Materials Science Program, Lakehead University, Thunder Bay, ON, Canada, 2Thunder Bay Regional Health Research Institute, Thunder Bay, ON, Canada, 3Chemistry, Lakehead University, Thunder Bay, ON, Canada, 4Thunder Bay Regional Health Sciences Centre, Thunder Bay, ON, Canada, 5Northern Ontario School of Medicine, Thunder Bay, ON, Canada |
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Hyperpolarized (HP) xenon-129 (129Xe) freely dissolves in pulmonary blood and travels to highly perfused organs. Dissolved phase HP 129Xe imaging is commonly used for evaluating gas-blood exchange in lungs, imaging cerebral perfusion, detecting hemodynamic response, and kidney perfusion. However, the signal-to-noise ratio (SNR) of HP 129Xe dissolved phase images varies between breath-holds, especially for brain imaging. In this work, we demonstrated a significant reduction in the variability of MRI image SNR by implementing an additional depolarization pulse prior to image acquisition. |
| 3575
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2D and 3D Spiral for Diffusion Weighted MRI with Hyperpolarized 129Xe | |
| Abdullah S. Bdaiwi1,2, Matthew M. Willmering1, Hui Wang3, and Zackary I. Cleveland1,2,4,5 | ||
1Center for Pulmonary Imaging Research, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States, 2Biomedical Engineering Department, University of Cincinnati, Cincinnati, OH, United States, 3Philips, Cincinnati, OH, United States, 4Department of Pediatrics, University of Cincinnati, Cincinnati, OH, United States, 5Division of Pulmonary Medicine, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, United States |
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Diffusion-weighted hyperpolarized 129Xe MRI is a validated measure of lung microstructure and can assess changes in alveolar dimensions. These images are commonly acquired via 2D gradient recalled echo (GRE), but 129Xe GRE images suffer from coarse resolution in the slice dimension and breath-hold durations (≤16 s) that may be difficult for pediatric and severely ill subjects. To overcome these limitations, we implemented 2D- and 3D-spiral (FLORET, Fermat looped, orthogonally encoded trajectories) sequences for 129Xe diffusion imaging. These sequences enable either rapid acquisition or high-resolution, isotropic lung coverage and display image quality and ADC accuracy comparable to that of conventional 2D-GRE. |
| 3576
|
Evaluating the Fractal Nature of 129Xe MRI Ventilation Heterogeneity | |
| Rachel L Eddy1,2, Alexander M Matheson3,4, Marrissa J McIntosh3,4, and Grace Parraga3,4 | ||
1St. Paul's Hospital, UBC Centre for Heart Lung Innovation, Vancouver, BC, Canada, 2Division of Respiratory Medicine, Department of Medicine, University of British Columbia, Vancouver, BC, Canada, 3Robarts Research Institute, London, ON, Canada, 4Department of Medical Biophysics, Western University, London, ON, Canada |
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Pulmonary ventilation has been shown to follow a fractal distribution using fluorescence imaging. 129Xe MRI provides high spatial-temporal resolution images of pulmonary ventilation so here, we aimed to determine the fractal properties of 129Xe MRI ventilation heterogeneity using the box-counting method. In 25 patients with asthma, MRI ventilation heterogeneity followed a power law and mean fractal dimension for MRI signal ranged from 1.39-1.82. Fractal analysis can provide a new tool to measure regional MRI ventilation heterogeneity and investigate pulmonary structure-function relationships in patients with lung disease. |
| 3577
|
Dual-Phase Imaging of Cardiac Metabolism using Hyperpolarized [1-13C]Pyruvate | |
| Junjie Ma1, Craig R. Malloy1,2,3, Crystal E. Harrison1, James Ratnakar1, Galen D. Reed4, Vlad G. Zaha1,2, and Jae Mo Park1,3,5 | ||
1Advanced Imaging Research Center, UT SOUTHWESTERN MEDICAL CENTER, Dallas, TX, United States, 2Internal Medicine, UT Southwestern Medical Center, Dallas, TX, United States, 3Radiology, UT Southwestern Medical Center, Dallas, TX, United States, 4GE Healthcare, Dallas, TX, United States, 5Electrical and Computer Engineering, UT Dallas, Richardson, TX, United States |
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A dual-phase 13C imaging sequence that acquires multi-echo images of hyperpolarized [1-13C]pyruvate, [1-13C]lactate, [1-13C]alanine and [13C]bicarbonate was implemented to acquire metabolic data at both end systole and end diastole from the human heart in a single injection. The proposed method was demonstrated in short-axis and long-axis ventricle views. |
| 3578 | Metabolic response of radiotherapy in patient-derived glioblastoma xenografts using hyperpolarized magnetic resonance | |
| Travis Salzillo1, Vimbai Mawoneke2, Joseph Weygand2, Akaanksh Shetty2, Joy Gumin3, Niki Zacharias2, Seth Gammon2, David Piwnica-Worms2, Gregory Fuller4, Christopher Logothetis5, Frederick Lang3, and Pratip Bhattacharya2 | ||
1Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX, United States, 2Cancer Systems Imaging, University of Texas MD Anderson Cancer Center, Houston, TX, United States, 3Neurosurgery, University of Texas MD Anderson Cancer Center, Houston, TX, United States, 4Pathology, University of Texas MD Anderson Cancer Center, Houston, TX, United States, 5Genitourinary Medical Oncology, University of Texas MD Anderson Cancer Center, Houston, TX, United States |
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Glioblastoma is an aggressive cancer with a median survival of 16 months. Thus, waiting for changes in tumor volume to determine prognosis is too slow to benefit the patient. In this study, we show that in vivo measurements of tumor metabolism with hyperpolarized magnetic resonance can detect changes more rapidly and reliably than conventional anatomic MRI throughout all stages of tumor progression. These data are supported through ex vivo metabolic profiling. Interpretation of these results demonstrate the value that hyperpolarized magnetic resonance can bring to the clinic by addressing specific challenges encountered throughout the the care of glioblastoma patients. |
| 3579 | Hyperpolarized 13C MRI of Fumarate Metabolism for Imaging Necrosis in Hepatitis Mice by Parahydrogen-induced Polarization. | |
| Shingo Matsumoto1, Neil J. Stewart1, Hitomi Nakano1, Takuya Hashimoto2, and Hiroshi Hirata1 | ||
1Information Science and Technologies, Hokkaido University, Sapporo, Japan, 2Department of Chemistry, Chiba University, Chiba, Japan |
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Hyperpolarized [1-13C]fumarate is a promising MRI biomarker for cellular necrosis, which plays an important role in various diseases and cancer treatment response. To demonstrate the feasibility of hyperpolarized MRI of [1-13C]fumarate metabolism using parahydrogen-induced polarization (PHIP) – a low-cost alternative to dissolution dynamic nuclear polarization (dDNP), a cost-effective synthetic pathway for high-yield production of a fumarate precursor [1-13C]acetylenedicarboxylate was developed. A simple hydrogenative PHIP set-up was used to generate hyperpolarized [1-13C]fumarate at sufficient polarization and concentration for in vivo [1-13C]fumarate metabolic MRS/MRI in acetaminophen-induced murine model of hepatitis. |
| 3580 | Dependency of glycolytic factors in HCC lactate and alanine flux as measured by hyperpolarized 13C MRI | |
| Qianhui Dou1, Aaron K. Grant1, Cody K. Callahan1, Muneeb Ahmed1, and Leo Lee Tsai1 | ||
1Radiology, Beth Israel Deaconess Medical Center, Boston, MA, United States |
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This study investigated the feasibility of hyperpolarized 13C (h13C) MRI as diagnostic tool to monitor hepatocellular carcinoma (HCC) activity. h13C MRI showed significant increase in pyruvate-lactate conversion and decrease in pyruvate-alanine in N1S1 HCC tumors following stimulation from nearby hepatic radiofrequency ablation, while no such changes were seen with the MCA-RH7777 HCC tumors, despite increased tumor burden or proliferation in both cell lines. The h13C measurements matched mRNA expression patterns of glycolysis-related genes, which were relatively lower for MCA-RH7777. h13C pyruvate MRI may provide insight into malignant tumor behavior but is contingent on the activity of key glycolytic regulators. |
| 3581 | Imaging Treatment Response with Hyperpolarized Pyruvate in Anaplastic Thyroid Carcinoma | |
| Christopher M Walker1, Zhan Xu1, Keith Michel1, Gary Martinez1, Collin J. Harlan1, Jeremy W. Gordon2, Stephanie Carlon1, Sandra Williams1, Freddy Gonzalez1, Stacy Hash1, Jerell Jones1, Asa McCoy1, Brandy Willis1, Michelle Underwood1, Andrew Day3, Moin Chariwala3, Dao Le4, Gregory Waligorski3, Daniel B. Vigneron2, Dawid Schellingerhout5, Stephen Y. Lai6, and James A. Bankson1 | ||
1Imaging Physics, MD Anderson Cancer Center, Houston, TX, United States, 22. Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, San Francisco, CA, United States, 3Center for Advanced Biomedical Imaging, MD Anderson Cancer Center, Houston, TX, United States, 4Nuclear Medicine, MD Anderson Cancer Center, Houston, TX, United States, 5Nueroradiology, MD Anderson Cancer Center, Houston, TX, United States, 6Head and Neck Surgery, MD Anderson Cancer Center, Houston, TX, United States |
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This case report presents the detection of hyperpolarized lactate production in a patient with anaplastic thyroid carcinoma. Lactate signal was observed following injection of hyperpolarized pyruvate and the signal was well localized to the tumor. The normalized lactate signal was reduced eight days following the onset of systemic therapy with Pembro and Lenvatinib. |
| 3582 | Off-Resonance Correction with Self-Estimated Field Map for Hyperpolarized 13C Metabolic Imaging | |
| Xiaoxi Liu1, Shuyu Tang1,2, Xucheng Zhu1,3, and Peder E.Z. Larson1 | ||
1Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, United States, 2HeartVista, Inc., Los Altos, CA, United States, 3GE Healthcare, Sunnyvale, CA, United States |
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Hyperpolarized 13C magnetic resonance imaging is a non-invasive imaging tool to assess metabolic process in-vivo that has been most commonly applied to imaging cancer and heart disease. Spiral readout, as a rapid acquisition technique, is commonly used to acquire hyperpolarized metabolic data. However, the spiral readout is sensitive to the off-resonance effect and has blurring artifacts as a result. The blurring also affects the measurement of metabolism. In this project, we investigated two off-resonance correction methods with self-estimated field maps and applied them on different anatomies. |
| 3583 | In Vivo Evaluation of Glutaminase Activity with Hyperpolarized [5-13C,4,4-2H2,5-15N]-L-Glutamine in PDAC | |
| Roozbeh Eskandari1, Arsen Mamakhanyan1, Michelle Saoi2, Kristin L Granlund1, Justin Cross2, Craig B Thompson3, and Kayvan Rahimi Keshari1,4 | ||
1Radiology, Memorial Sloan Kettering Cancer Center, New York, NY, United States, 2Memorial Sloan Kettering Cancer Center, New York, NY, United States, 3Cancer Biology & Genetics Program Share, Memorial Sloan Kettering Cancer Center, New York, NY, United States, 4Radiology, Memorial Sloan Kettering, New York, NY, United States |
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Aberrations in glutaminase enzyme expression are associated with a variety of pathologies, and an in vivo probe to quantify flux through this pathway may provide a new layer of information. We developed a custom-synthesized compound, [5-13C,4,4-2H2,5-15N]-L-Glutamine, as a hyperpolarized MRI probe for glutaminase activity. Triple labeling of glutamine and D2O solvation reduces quadrupolar relaxation and extends both T1 and T2, facilitating in vivo imaging. We were able to acquire 13C spectroscopic data on a subcutaneous PDAC xenograft murine model and detect in vivo conversion of hyperpolarized glutamine to glutamate, which permits further exploration of this imaging probe in the future. |
| 3584 | Magnetic Resonance Imaging Comparisons of Renal Cell Carcinoma Patient-derived Xenografts | |
| Joao Piraquive1, Hongjuan Zhao2, Rosalie Nolley2, Robert Bok1, James D. Brooks2, Donna M. Peehl1, John Kurhanewicz1, and Renuka Sriram1 | ||
1Department of Radiology and Biomedical Imaging, University of California San Francisco, University of California San Francisco, San Francisco, CA, United States, 2Department of Urology, Stanford University, Stanford, CA, United States |
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We demonstrated substantial morphologic and glycolytic metabolic differences using proton and hyperpolarized 13C magnetic resonance imaging, respectively between and within RCC patient derived xenografts (PDXs). Our findings showed substantial inter-PDX differences in tumor growth rates, as well as the cystic and necrotic components. Furthermore, the xenograft (XEN) established from cell lines derived from the PDX showed significant morphological differences from the parent PDX. Interestingly, upon comparison of two subsequent passages of the same PDX, we found that while the morphological similarities persisted, the glycolytic capacity was significantly increased in the latter passage, implying natural selection of the more aggressive cells. |
| 3585 | In Vivo T2* of Hyperpolarized 13C-Metabolites in Human Brain, Heart, Kidney, and Spleen: An Imaging Approach | |
| Junjie Ma1, Crystal E. Harrison1, James Ratnakar1, Galen D. Reed2, Rolf F. Schulte3, Vlad G. Zaha1,4, Craig R. Malloy1,4,5, and Jae Mo Park1,5,6 | ||
1Advanced Imaging Research Center, UT SOUTHWESTERN MEDICAL CENTER, Dallas, TX, United States, 2GE Healthcare, Dallas, TX, United States, 3GE Healthcare, Munich, Germany, 4Internal Medicine, UT Southwestern Medical Center, Dallas, TX, United States, 5Radiology, UT Southwestern Medical Center, Dallas, TX, United States, 6Electrical and Computer Engineering, UT Dallas, Richardson, TX, United States |
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Multi-echo 13C spiral imaging sequence combined with a spectral-spatial radiofrequency pulse can measure T2* of 13C-labeled metabolite signals in vivo. In this study, we measured T2*s of hyperpolarized [1-13C]pyruvate and products in human heart, brain, kidney and spleen. |
| 3586 | Kinetic Analysis of Multi-resolution Hyperpolarized 13C Human Brain MRI | |
| Jasmine Y Graham1, Adam W Autry2, Yaewon Kim2, Robert A Bok2, Yan Li2, Peder EZ Larson1,2, Daniel B Vigneron1,2, and Jeremy W Gordon2 | ||
1Bioengineering, UC San Francisco, UC Berkeley, San Francisco, CA, United States, 2Radiology and Biomedical Imaging, UC San Francisco, San Francisco, CA, United States |
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Utilizing a multi-resolution acquisition for hyperpolarized [1-13C]pyruvate brain MRI (7.5 mm in-plane for pyruvate and 15 mm in-plane resolution for lactate & bicarbonate) minimized partial volume effects from vascular pyruvate signals while maintaining the SNR of the downstream metabolites. In the healthy volunteers studied, higher resolution HP 13C-pyruvate multi-slice EPI images improved the quantification of kinetic rates in the brain. Selected voxels near veins and in white and gray matter showed on average >20% higher kPL using higher resolution pyruvate images, consistent with reduced partial volume contributions from vascular HP 13C-pyruvate. |
| 3587 | A genetic algorithm-optimized hetero-nuclear polarization transfer pulse sequence for metabolic imaging | |
| Vencel Somai1,2, Felix Kreis3, Adam Gaunt1, and Kevin M Brindle1,4 | ||
1Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing Centre, Robinson Way, Cambridge, United Kingdom, 2Department of Radiology, University of Cambridge, School of Clinical Medicine Box 218, Cambridge Biomedical Campus, Cambridge, United Kingdom, 3Department of Information Technology and Electrical Engineering, ETH Zurich, Rämistrasse 101, Zurich, Switzerland, 4Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, United Kingdom |
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An optimized polarization transfer pulse designed using a genetic algorithm is presented, which has greater immunity to the effects of B0 and B1 field inhomogeneity and ~2 times lower peak B1 compared to the BINEPT pulse sequence. The optimization provides a simple framework that accounts for finite pulse lengths and relaxation and outputs a shaped pulse on each frequency channel. Performance was tested on a [15N2]urea phantom at thermal equilibrium, where the polarization transferred from protons to 15N was 1.32 times greater than that transferred using BINEPT. Partial transfer of polarization from hyperpolarized 15N to proton was also demonstrated. |
| 3588 | DNP Polarizing Agents in Preclinical HP MRS: Influence in the Context of Transient Ischemic Stroke | |
| Thanh Phong Lê1,2, Lara Buscemi3, Mario Lepore4, Lorenz Hirt3, Jean-Noël Hyacinthe1,5, and Mor Mishkovsky2 | ||
1Geneva School of Health Sciences, HES-SO University of Applied Sciences and Arts Western Switzerland, Geneva, Switzerland, 2Laboratory of Functional and Metabolic Imaging, EPFL (Swiss Federal Institute of Technology in Lausanne), Lausanne, Switzerland, 3Department of Clinical Neurosciences, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland, 4Center for Biomedical Imaging (CIBM), EPFL, Lausanne, Switzerland, 5Image Guided Intervention Laboratory, University of Geneva (UNIGE), Geneva, Switzerland |
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Used at low concentration in DNP sample preparations, radicals are typically chemically highly reactive species that could potentially interfere with the biochemical processes assessed in HP MR experiments. In this work, we investigate the influence of the nitroxyl radical TEMPOL on the cerebral metabolic response to a bolus of hyperpolarized [1-13C]lactate in a mouse model of transient ischemic stroke. Our results show that TEMPOL, administered at the same dose as when used as a polarizing agent for DNP, alters substantially the metabolic outcome of the experiment and notably results in a significantly different pyruvate labelling after hyperpolarized lactate infusion. |
| 3589 | Transportable hyperpolarized glucose: protocol for sample extraction and delivery | |
| Andrea Capozzi1, Jan Kilund2, Magnus Karlsson2, Mathilde Hauge Lerche2, and Jan Henrik Ardenkjær-Larsen2 | ||
1LIFMET, EPFL, Lausanne, Switzerland, 2Health Technology, Technical University of Denmark, Kgs. Lyngby, Denmark |
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Our vision is to make it possible to deliver hyperpolarized compounds to MR facilities that currently have no access to hyperpolarization technology. Today this is not the case and represents hyperpolarized-MR via dissolution Dynamic Nuclear Polarization (dDNP) main shortcoming. The reason is intrinsic in the technique and deals with the presence, in the dDNP sample, of organic free radicals necessary to generate the hyperpolarization. Herein, we demonstrate, for the first time, transportation at cryogenic temperature and remote dissolution of hyperpolarized glucose. The core idea of this project is to exploit the non-persistency of UV-induced radicals for dDNP. |
| 3590 | Hyperpolarized [1-13C] pyruvate MR spectroscopic imaging to detect metabolic changes in liver in a MCD rat model of fatty liver disease | |
| Joao Piraquive1, Shubhangi Agarwal1, Robert Bok1, John Kurhanewicz1, Aras Mattis2,3, Jaqueline Maher3,4, Cornelius von Morze5, and Michael A. Ohliger1,3 | ||
1Department of Radiology and Biomedical Imaging, University of California San Francisco, University of California San Francisco, San Francisco, CA, United States, 2Department of Pathology, University of California San Francisco, San Francisco, CA, United States, 3Liver center, University of California, San Francisco, CA, United States, 4Department of Medicine, University of California San Francisco, San Francisco, CA, United States, 5Biomedical Magnetic Resonance Laboratory, Washington University School of Medicine, St. Louis, MO, United States |
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Hyperpolarized 13C MRI was used to noninvasively detect metabolic changes in a rat model of non-alchoholic steatohepatitis. Rats were fed a methionine- and choline-deficient (MCD) diet for up to 18 weeks. In this preliminary study, we showed a significant increase in fat signal fraction and borderline-signifcant decrease in 13C lactate production in rats fed the MCD diet. Findings in this work suggest that HP 13C pyruvate can be a promising tool to monitor noninvasively the progress of fatty liver disease in patients. |
| 3591 | Constrained UNFOLD (CoUNFOLD)-a New Constrained Reconstruction for Hyperpolarized 13C Pyruvate Imaging | |
| Zhan Xu1, Christopher M Walker1, Collin J Harlan1, Keith A Michel1, Gary V Martinez1, and James A Bankson1,2 | ||
1Imaging Physics, MD Anderson Cancer Center, Houston, TX, United States, 2UT Health Graduate School of Biomedical Sciences, The University of Texas MD Anderson Cancer, Houston, TX, United States |
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A new pharmacokinetic-model-based constrained reconstruction method CoUNFOLD is introduced for hyperpolarized 13C pyruvate imaging. This method extended classic UNFOLD method by introducing model constraint which described the signal evolution of multiple substrates. CoUNFOLD successfully accelerated the data acquisition, and the reconstruction was implemented on single channel. An in silico experiment demonstrated the accuracy of reconstruction at a reduction factor of 2. The quantitative estimation of the conversion ratio from pyruvate to lactate was achieved with high accuracy when peak pyruvate SNR was as low as 20 |
| 3592 | Hyperpolarized 13C-pyruvate MR imaging in rodent model of ventricular fibrillation cardiac arrest: A feasibility study | |
| Hyeong Yeon Lee1, Najmiddin Mamadjonov2, Nguyen Trong Nguyen2, Luu-Ngoc Do3, Tien Ahn Nguyen3, and Ilwoo Park3,4,5 | ||
1Emergency Medicine, Chonnam National University Hospital, Gwangju, Korea, Republic of, 2Biomedical Science, Chonnam National University, Gwangju, Korea, Republic of, 3Radiology, Chonnam National University, Gwangju, Korea, Republic of, 4Radiology, Chonnam National University Hospital, Gwangju, Korea, Republic of, 5Artificial Intelligence Convergence, Chonnam National University, Gwangju, Korea, Republic of |
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This study demonstrated that hyperpolarized 13C metabolic imaging can identify the metabolic changes within 1 hour of return of spontaneous circulation in rodent model of ventricular fibrillation-induced cardiac arrest. Brain histology performed at 72 hours after ROSC showed marked difference in the levels of neuronal death and reactive astrocyte change between the cardiac arrest model and sham control. The results from this study suggest that this new metabolic imaging technique may provide a unique and noninvasive imaging biomarker for assessing functional changes at early stage of post ROSC and warrant further investigation. |
| 3593 | Accelerating Hyperpolarized 13C Spiral Chemical Shift Imaging with Joint Spectral-Spatial Low Rank Plus Sparse Reconstruction | |
| Minjie Zhu1, Stephen DeVience2, and Dirk Mayer1 | ||
1University of Maryland Baltimore, Baltimore, MD, United States, 2Scalar Magnetics, LLC, Cuyahoga Falls, OH, United States |
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The goal of this study is to incorporate the spectral dimension into the Low Rank Plus Sparse Reconstruction algorithm with application of undersampled dynamic Hyperpolarized 13C imaging. The proposed method can be used to increase temporal and/or spatial resolution without significantly compromising image quality. |
| 3594 | Comparing aspartate and bicarbonate produced from hyperpolarized 1-13C pyruvate as markers of renal gluconeogenic flux | |
| Hikari A. I. Yoshihara1, Arnaud Comment2,3, and Juerg Schwitter4,5 | ||
1Laboratory for Functional and Metabolic Imaging, Institute of Physics, Swiss Federal Institute of Technology, Lausanne (EPFL), Lausanne, Switzerland, 2Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge, United Kingdom, 3General Electric Healthcare, Chalfont St Giles, United Kingdom, 4Division of Cardiology, Lausanne University Hospital (CHUV), Lausanne, Switzerland, 5Cardiac MR Center, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland |
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Labeled metabolites of hyperpolarized 1-13C pyruvate, including aspartate, malate and fumarate are detected in the rat kidney in vivo, indicating the possibility of detecting gluconeogenic flux. Pyruvate-to-bicarbonate conversion in the fasted rat liver is a marker of PEP-CK flux. Fasting resulted in lower bicarbonate and higher aspartate in the kidney. Conversely, treatment with the PEP-CK inhibitor 3-MPA did not affect bicarbonate production but did yield a lower normalized aspartate signal, with a 12-fold reduction in fasted rats. Renal pyruvate-to-bicarbonate conversion is therefore largely attributable to pyruvate hydrogenase flux, while pyruvate-to-aspartate conversion is a potential marker of renal gluconeogenesis. |
| 3595 | Metabolic Role of ATM in Development of Diffuse Large B-cell Lymphoma | |
| Aditya Jhajharia1, Sui Seng Tee1, Maninder Singh1, Sausan Jaber2, Binny Bhandary3, Brian Polster2, Ronald B. Gartenhaus3,4, Kavita Bhalla3, and Dirk Mayer1 | ||
1Diagnostic Radiology and Nuclear Medicine, University of Maryland School of Medicine, Baltimore, MD, United States, 2Department of Anesthesiology, University of Maryland, Baltimore, MD, United States, 3Department of Medicine, University of Maryland, Baltimore, MD, United States, 4Veterans Administration Medical Center, Baltimore, MD, United States |
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Ataxia-telangiectasia mutated (ATM) kinase regulates critical metabolic processes of B-cell lymphoid malignancies. Diffuse large B-cell lymphoma (DLBCL) is clinically a very aggressive tumor subtype. This study investigates the role of ATM in metabolism. Oxygen consumption rate measurements showed decreased respiration in DLBCL cells lacking ATM. MRS of hyperpolarized [1-13C]pyruvate in DLBCL line HLY that were either wild-type or had ATM knocked down showed increased conversion of hyperpolarized pyruvate to lactate in HLY cells lacking ATM. These results indicate that deregulation of mitochondrial structure/function due to ATM deficiency results in metabolic changes and may contribute to the development of cancer. |
| 3596
|
Imaging pH, metabolism and hypoxia using hyperpolarized 13C-MRI and [18F]FMISO-PET to predict NIS expression in MSC gene therapy in glioblastoma | |
| Martin Grashei1, Carolin Kitzberger2, Jason G. Skinner1, Sandra Sühnel1, Geoffrey J. Topping1, Elisabeth Bliemsrieder1, Christian Hundshammer1, Katja Steiger3, Peter J. Nelson4, Rainer Glaß5, Wolfgang Weber1, Christine Spitzweg2, and Franz Schilling1 | ||
1Department of Nuclear Medicine, Klinikum rechts der Isar, Technical University of Munich, School of Medicine, Munich, Germany, 2Medizinische Klinik und Poliklinik IV-Campus Großhadern, University Hospital of Munich, Ludwig-Maximilians-University Munich, Munich, Germany, 3Department of Pathology, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany, 4Medizinische Klinik und Poliklinik IV, University Hospital of Munich, Ludwig-Maximilians-University Munich, Munich, Germany, 5Neurosurgical Research University Clinics, Ludwig-Maximilians-University Munich and Walter-Brendel-Centre of Experimental Medicine, Munich, Germany |
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A novel treatment approach for glioblastoma is based on mesenchymal stem cell (MSC)-mediated gene therapies whereby cell accumulation can be influenced by the tumor microenvironment. Here, we demonstrate the ability to image pH, metabolic pyruvate-lactate conversion and hypoxia in glioblastoma using hyperpolarized [1,5-13C2,3,6,6,6-D4]zymonic acid-MRSI, [1-13C]pyruvate-MRI and [18F]FMISO-PET as predictors for hypoxia-targeted sodium-iodide-symporter (NIS)-expression of tumor-infiltrating MSCs assessed by 124I-PET. Observed hypoxia (SUVmean = 0.49±0.05) was confirmed by histology and occurred together with increased lactate-production (AUCmean = 1.14±0.17) and mild acidification (pHmean = 7.34±0.02). This shows to be a suitable environment for NIS-MSC-activity, thereby allowing efficient therapy. |
| 3773 | Global and Direct Electrical Properties Tomography Method Based on the Linear Integral Equations for Impedivity | |
| Motofumi Fushimi1, Naohiro Eda1, and Takaaki Nara1 | ||
1The University of Tokyo, Tokyo, Japan |
||
The present paper introduces novel reconstruction methods for electrical properties tomography (EPT), in which conductivity and permittivity are reconstructed from the complex B1 field, and phase-based EPT, in which only conductivity is reconstructed from the B1 phase. The proposed methods reconstruct electrical properties (EPs) by solving a linear integral equation derived from Helmholtz's identity, and does not require calculation of the second-order derivatives of the measured data nor iterative updating of the estimates. Numerical simulations and phantom experiments showed that the proposed method could retrieve EPs more stably than the conventional method that solves a linear partial differential equation. |
| 3774 | New Approaches for Simultaneous Noise Suppression and Edge Preservation to Achieve Accurate Quantitative Conductivity Mapping in Noisy Images | |
| Anita Karsa1 and Karin Shmueli1 | ||
1Department of Medical Physics and Biomedical Engineering, University College London, London, United Kingdom |
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Due to their extreme noise amplification, current Quantitative Conductivity Mapping (QCM) techniques require high SNR images. Simultaneous Quantitative Susceptibility Mapping and QCM uses low-SNR gradient-echo sequences, creating a need for QCM methods appropriate for noisy images. Here we proposed, optimised, and compared several new QCM methods (all shared on https://xip.uclb.com/i/software/MRI_conductivity.html) built on the widely-used phase-based formula and its equivalent, less popular integral form. We found that solving the integral equation provided lower errors and better edge preservation in both simulated and in-vivo images, and that edge preservation combining magnitude-based and image-segmentation-based techniques resulted in the best in-vivo conductivity map. |
| 3775 | Optimal Kernel Radii for Calculating the Derivatives of Noisy B1 Phase for Accurate Phase-Based Quantitative Conductivity Mapping | |
| Anita Karsa1, Patrick Fuchs1, and Karin Shmueli1 | ||
1Department of Medical Physics and Biomedical Engineering, University College London, London, United Kingdom |
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Quantitative conductivity mapping (QCM) techniques use the first spatial derivatives and/or the Laplacian of the B1 phase. These are commonly estimated by fitting a 3D quadratic function within a kernel around each voxel. However, small kernels lead to severe noise amplification and large kernels induce inaccuracies. Here we determined the optimal kernel radii across a range of magnitude SNR using an anthropomorphic, numerical brain phantom. The optimal kernel size decreased with increasing SNR. Calculating the first derivatives required smaller kernels than calculating the Laplacian making QCM methods using first derivatives likely more accurate than Laplacian-based techniques. |
| 3776 | An Iterative Method for Electrical Properties Tomography Based on the Helmholtz Decomposition for the Electric Field | |
| Naohiro Eda1, Motofumi Fushimi1, and Takaaki Nara1 | ||
1The University of Tokyo, Tokyo, Japan |
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This paper proposes a novel, integral-equation-based (IE-based) reconstruction method for magnetic resonance electrical properties tomography (MREPT). The proposed method can reconstruct the electric field and EPs simultaneously based on the Helmholtz decomposition of the electric field. In the proposed algorithm, we iteratively apply the projections onto the spaces in which the true electric field is contained. An advantage of the proposed method is that convergence is theoretically guaranteed in this iterative process. The efficacy of the proposed method is validated through numerical simulations. |
| 3777 | Uncertainty assessment under repeatability conditions in Helmholtz-based electric properties tomography | |
| Alessandro Arduino1, Francesca Pennecchi1, Ulrich Katscher2, Luca Zilberti1, and Maurice Cox3 | ||
1Istituto Nazionale di Ricerca Metrologica (INRIM), Torino, Italy, 2Philips Research Laboratories, Hamburg, Germany, 3National Physical Laboratory (NPL), Teddington, United Kingdom |
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This work shows the uncertainty evaluation under repeatability conditions of the phase-based Helmholtz-electric properties tomography (EPT) technique. Repeated MRI scans of a homogeneous cylindrical phantom are analyzed with appropriate statistical techniques to evaluate the covariance matrix of the EPT input. This matrix is propagated through the EPT technique according to the law of propagation of uncertainty. The estimated electric conductivity is highly repeatable and exhibits a spatial dispersion, whose average value, within a central region, gives an accurate estimate of the phantom conductivity. The described approach will be applied in future to extend the characterization under reproducibility conditions. |
| 3778
|
EPTlib: an open-source C++ library of electric properties tomography methods | |
| Alessandro Arduino1, Umberto Zanovello1, Luca Zilberti1, and Oriano Bottauscio1 | ||
1Istituto Nazionale di Ricerca Metrologica (INRIM), Torino, Italy |
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This abstract introduces EPTlib, an open-source, extensible C++ library collecting electric properties tomography (EPT) methods. Currently, the library implements three methods (Helmholtz-EPT, convection reaction–EPT and gradient-EPT), but the list will be updated in the future. EPTlib comes along with a console application that allows to run all the implemented methods. After a brief description of the software architecture and of the EPT methods, an example of usage of each implemented method with simulated input data is provided. |
| 3779 | Evidence for tissue dielectric property differences between neonates and adults: a retrospective study using MR-EPT | |
| Roy Kurtzbard1, Anthony Price2, Joseph V Hajnal1,2, Jeffrey W Hand2, and Shaihan J Malik1,2 | ||
1Biomedical Engineering Department, School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom, 2Centre for the Developing Brain, School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom |
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Electromagnetic simulations for RF safety calculation require knowledge of tissue dielectric properties, but these are not well understood for neonates whose tissues have much higher water content than adults. This work retrospectively used MR-EPT on archived raw data obtained from a study on 800+ neonates, to measure tissue conductivity and permittivity at 128MHz. Presented are initial results from 50 subjects. The measured properties are rather noisy at the individual level, but across the whole cohort the median brain conductivity in neonates is approximately 1.8 times greater than in adults, in line with expectations from scaling arguments. |
| 3780 | Fast 3D Undersampled Bloch-Siegert based B1+ Mapping for use in MREPT | |
| Safa Ozdemir1, Efe Ilicak1, Carmen Stutz1, Mara Berger1, Jascha Zapp1, Lothar R. Schad1, Yusuf Z. Ider2, and Frank G. Zöllner1,3 | ||
1Computer Assisted Clinical Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany, 2Electrical and Electronics Engineering, Bilkent University, Ankara, Turkey, 3Mannheim Institute for Intelligent Systems in Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany |
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Magnetic Resonance Electrical Properties Tomography (MREPT) technique utilizes complex B1+ information to obtain conductivity (σ) and permittivity (ϵ). Since obtaining B1+ magnitude is rather time consuming, several phase-based MREPT methods were previously suggested. However, these methods contain inaccuracies especially towards the periphery of the imaged object. In this paper, we utilize one of the fastest B1+ magnitude mapping techniques in order to obtain fast and accurate B1+ magnitude maps to be used in conductivity imaging. Phantom measurements show that accurate 3D B1+ magnitude maps can be acquired in less than 30 seconds, therefore improving the practicality of conductivity imaging. |
| 3781 | Fast virtual B1-mapping for the in silico characterization of EPT | |
| Alessandro Arduino1 and Luca Zilberti1 | ||
1Istituto Nazionale di Ricerca Metrologica (INRIM), Torino, Italy |
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A fast modelling of B1-mapping techniques is proposed for the in silico characterization of electric properties tomography method. The performances of three B1-mapping techniques are analyzed on a realistic model problem, obtaining information on the systematic errors and on the random errors through the application of a Monte Carlo method. An Helmholtz-based electric properties tomography technique is tested on input provided by the B1-mapping techniques. |
| 3782 | Permittivity Mapping with B1-TRAP | |
| Santhosh Iyyakkunnel1,2, Carl Ganter3, Francesco Santini1,2, and Oliver Bieri1,2 | ||
1Department of Radiology, University Hospital Basel, Basel, Switzerland, 2Department of Biomedical Engineering, University of Basel, Basel, Switzerland, 3Department of Radiology, Technical University of Munich, Munich, Germany |
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Permittivity mapping strongly depends on the accuracy and the signal-to-noise ratio (SNR) of the underlying B1+ magnitude estimation method. In this work, we assess the suitability of a transient phase SSFP method, termed B1-TRAP, for permittivity mapping and compare this B1+ mapping method with the commonly-used Actual Flip Imaging (AFI) method. |
| 3783 | An Application of a Projected Newton Method to Electrical Properties Estimation via Global Maxwell Tomography | |
| Jose EC Serralles1, Ilias I Giannakopoulos2, Jacob K White1, Luca Daniel1, and Riccardo Lattanzi2,3,4 | ||
1Electrical Engineering and Computer Science, Computational Prototyping Group (CPG), Research Laboratory of Electronics (RLE), Department of Electrical Engineering and Computer Science (EECS), Massachusetts Institute of Technology (MIT), Cambridge, MA, United States, 2Center for Advanced Imaging Innovation and Research (CAI2R), Department of Radiology, New York University Grossman School of Medicine, New York, NY, United States, 3The Bernard and Irene Schwartz Center for Biomedical Imaging (CBI), Department of Radiology, New York University Grossman School of Medicine, New York, NY, United States, 4Vilcek Institute of Graduate Biomedical Sciences, New York University Grossman School of Medicine, New York, NY, United States |
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Global Maxwell Tomography (GMT) is a recently introduced technique that estimates tissue electrical properties from magnetic resonance measurements by solving an inverse scattering problem. In this work, we propose a new implementation of GMT that uses a Projected Newton method to minimize the cost function, instead of the quasi-Newton method employed by the original GMT. We demonstrated the new approach with two numerical experiments, using a four--compartment phantom and a realistic head model. Compared to the results obtained with the original GMT, the number of iterations required for convergence was drastically reduced and the estimated EP were more accurate. |
| 3784 | Electrical Properties Reconstruction from Free Induction Decay Measurements | |
| Patrick Fuchs1 and Rob Remis1 | ||
1Microelectronics, Delft University of Technology, Delft, Netherlands |
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By incorporating scattering of dielectric tissue into the measurement model of the MRI signal we show a direct relationship between conductivity and permittivity of the tissue and the measured signal. Simplifying this for a known geometry a reconstruction of the dielectric properties is demonstrated based on the most simple of MRI signals, the finite induction decay or FID. This relationship can of course be exploited for more complicated applications such as local SAR, antenna design and optimisation and SNR computations, especially for high field applications. |
| 3785 | The electrical conductivity reconstruction using MR structural information | |
| Xiangdong Sun1, Chunyi Liu2, Lijun Lu2, Xiaoyun Liu1, and Wufan Chen1,2 | ||
1School of Automation Engineering,University of Electronic Science and Technology of China, Chengdu, China, 2School of Biomedical Engineering, Southern Medical University, Guangzhou, China |
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The conductivity of biological tissues can be potentially used for a cancer diagnostic. Thus, imaging conductivity is useful for clinical applications. Here, we developed a conductivity imaging method based on the gradient conductivity imaging method by incorporating information from anatomical MR images. The characteristic of the defined prior was extracting the structure information and guided the conductivity reconstruction. To evaluate the performance of the proposed method, the electromagnetic field and magnitude images were simulated for a cylindrical phantom and brain model. The results demonstrated that the proposed method preserves more details of the conductivity images and mitigates the noise affection. |
| 3786 | Comparison of MR-based low-frequency electrical conductivity tensor using DT-MREIT and CTI: a biological tissue phantom study | |
| Saurav Zaman Khan Sajib1, Munish Chauhan1, Sulagna Sahu1, Enock Boakye1, and Rosalind J Sadleir1 | ||
1School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ, United States |
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Diffusion tensor magnetic resonance electrical impedance tomography (DT-MREIT) and electrodeless conductivity tensor imaging (CTI) are two emerging modalities that can quantify low-frequency tissue anisotropic conductivity properties by considering the relationship between ion mobility and water diffusion. While both methods have potential applications to estimating neuro-modulation fields or formulating forward models used for electrical source imaging, a direct comparison of these two modalities has not yet been performed. Therefore, the aim of this study to test the equivalence of these two modalities. |
| 3787 | Phase Dispersion from Steady-State Signal Behavior in Phase-Sensitive Multiband Imaging with Application to MREIT | |
| Guita Banan1, Munish Chauhan2, Manish Amin1, Sudhir Ramanna3, Zahra Hosseini4, Essa Yacoub3, Michael Schär5, Thomas H Mareci1, and Rosalind J Sadleir2 | ||
1Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, United States, 2School of Biological and Health System Engineering, Arizona State University, Tempe, AZ, United States, 3University of Minnesota, Minneapolis, MN, United States, 4MR R&D Collaboration, Siemens Medical Solutions USA, Atlanta, GA, United States, 5Department of Radiology, Johns Hopkins University, Baltimore, MD, United States |
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Incorporating multiband excitation into phase-sensitive imaging introduces distortions in the phase measurements. We used simulations and phantom images to show that a previously unreported phase dispersion problem arises within multiband-slice phase maps. We show that this problem can be understood in terms of the steady-state signal behavior and propose imaging protocols to resolve it. Human scans using these protocols show minimal phase dispersion. We are adopting this protocol for our studies of phase-sensitive magnetic resonance electric impedance tomography (MREIT). |
| 3788 | Sensitivity and resolution improvement for in-vivo magnetic resonance current density imaging (MRCDI) of the human brain | |
| Cihan Göksu1,2, Klaus Scheffler2,3, Fróði Gregersen1,4,5, Hasan Hüseyin Eroğlu1,4, Rahel Heule2,3, Hartwig R. Siebner1,6,7, Lars G. Hanson1,4, and Axel Thielscher1,4 | ||
1Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital, Amager and Hvidovre, Denmark, 2High-Field Magnetic Resonance Center, Max-Planck-Institute for Biological Cybernetics, Tübingen, Germany, 3Department of Biomedical Magnetic Resonance, University of Tübingen, Tübingen, Germany, 4Section for Magnetic Resonance, DTU Health Tech, Technical University of Denmark, Kgs Lyngby, Denmark, 5Sino-Danish Center for Education and Research, Aarhus, Denmark, 6Department of Neurology, Copenhagen University Hospital, Bispebjerg, Denmark, 7Institute for Clinical Medicine, Faculty of Medical and Health Sciences, University of Copenhagen, Copenhagen, Denmark |
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Effective use of transcranial electrical stimulation (TES) in clinical and neuroscience applications requires the exact knowledge of TES currents. MRCDI uses MRI to measure the TES-induced magnetic fields for estimating the underlying current flow distributions. Their accuracy highly depends on the sensitivity and spatial resolution of the MR measurements. Here, we propose an advanced gradient-echo-based MRCDI method utilizing an optimized spoiling, acquisition-weighting, and navigators to achieve a noise sensitivity of 84pT at 2×2×3mm3 resolution for a total scan time of less than five minutes. We test the method's performance by phantom and human in-vivo experiments for two TES injection profiles. |
| 3789 | Optimization of SNR and the total acquisition time in MRCDI | |
| Mehdi Sadighi1, Mert Şişman1, and B. Murat Eyüboğlu1 | ||
1Electrical and Electronics Eng., Middle East Technical University (METU), Ankara, Turkey |
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The clinical applicability of magnetic resonance current density imaging (MRCDI) is highly dependent on the sensitivity of the acquired current-induced magnetic flux density ($$$\widetilde{B}_z$$$) distribution. Here, the combined effect of relevant parameters of the ICNE-SPGE pulse sequence on the SNR level and the total acquisition time of the $$$\widetilde{B}_z$$$ images are analyzed. The optimized sequence parameters are estimated to acquire $$$\widetilde{B}_z$$$ images with the highest possible SNR for a given acquisition time or the desired SNR in the shortest scan time. Besides, alternative sequence parameters are estimated to acquire the same SNR level for a given acquisition time. |
| 3790 | High-resolution whole-brain Conductivity Tensor Imaging of the human brain | |
| Marco Marino1,2, Dante Mantini1,2, and Giulio Ferrazzi2 | ||
1Research Center for Motor Control and Neuroplasticity, KU Leuven, Leuven, Belgium, 2IRCCS San Camillo Hospital, Venice, Italy |
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We propose a framework to achieve high-resolution whole-brain conductivity tensor imaging (CTI) with MRI at low frequencies. Our methodology overcomes the limitations of previous approaches based on B1 mapping techniques, both in terms of spatial resolution and brain coverage. This was attained by combining high-frequency conductivity estimates derived from a water-mapping technique with multi-b-value diffusion tensor imaging data. We obtained conductivity values for grey matter and white matter that are in line with previous studies. Overall, our findings highlight noteworthy within- and between- subject variability of the conductivity values. |
| 3791 | Establishing the Structurally Limited Healthy RBC to Barrier Ratio for 129Xe Gas Exchange MRI | |
| Bastiaan Driehuys1 and Elianna Ada Bier2 | ||
1Radiology, Duke University, Durham, NC, United States, 2Biomedical Engineering, Duke University, Durham, NC, United States |
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In quantitative 129Xe gas exchange MRI, the RBC/barrier ratio is emerging as a robust and important functional metric. However, it depends strongly on how it is measured, specifically on flip angle and repetition time. Moreover, we don’t yet have a clear understanding of its expected range in healthy subjects. Here, we demonstrate that by combining a physical diffusion model of 129Xe signal recovery with the recently introduced concept of flip angle to TR-equivalence, we can estimate the “structural limit” for the maximum RBC/barrier ratio expected in healthy adult subjects at any TR and flip angle. |
| 3792 | Within-session Repeatability of Pulmonary 129Xe Static and Dynamic Spectroscopy | |
| Elianna Ada Bier1, David G Mummy2, Junlan Lu3, and Bastiaan Driehuys2 | ||
1Biomedical Engineering, Duke University, Durham, NC, United States, 2Radiology, Duke University, Durham, NC, United States, 3Medical Physics Graduate Program, Duke University, Durham, NC, United States |
||
129Xe MRS has the potential to detect and characterize cardiopulmonary disease; however, clinical use demands a better understanding of the repeatability of these measurements. We studied the within-session repeatability of 129Xe MR static and dynamic spectroscopy of 117 pairs of scans with matched heart rates and adequate quality in both scans. Repeatability of each spectroscopic measurement was quantified using the coefficient of repeatability (CR), coefficient of variation (CV), and the intraclass correlation coefficient (ICC). All measurements had very little bias between the two scans and significant ICCs. The CRs for RBC:barrier and RBC amplitude oscillation were 0.07 and 4.2%, respectively. |
| 3793 | Assessment of Gas Exchange Parameters in Healthy and COPD Subjects using Hyperpolarized Xenon-129 MRI and Alveolar Gas-exchange Model | |
| Ozkan Doganay1, Minsuok Kim2, and Fergus Gleeson3 | ||
1Ege University, Izmir, Turkey, 2Loughborough University, Loughborough, United Kingdom, 3University of Oxford, Oxford, United Kingdom |
||
Hyperpolarized Xenon-129 MRI ventilation and gas exchange imaging and computational modelling provide a way to quantitatively assess gas ventilation and gas exchange parameters. This new imaging and modelling technique can be used to assess pulmonary diseases including COPD and emphysema and promises to be sensitive to variation in healthy subjects due to age, and/or early phases of pulmonary gas exchange impairment. |
| 3794 | A Comparison of Multi-breath Wash-in/Wash-out and RF-Contrast Hyperpolarized 129Xe Imaging Schemes for Quantifying Fractional Ventilation | |
| Luis Loza1, Tahmina Achekzai1, Stephen Kadlecek1, Hooman Hamedani1, Ian Duncan1, and Rahim R. Rizi2 | ||
1University of Pennsylvania, Philadelphia, PA, United States, 2Radiology, University of Pennsylvania, Philadelphia, PA, United States |
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Fractional ventilation, a metric denoting per-breath pulmonary gas replacement, has been shown to be sensitive to disease-induced alterations in ventilation in diseases such as emphysema. We have developed two discrete techniques for measuring FV using hyperpolarized 129Xe MR imaging and demonstrated their acquisition in a rat. Although the two techniques yield different FV maps, these two techniques offer both a quick and cost-effective method and a longer, robust method for probing pulmonary ventilation. |
| 3795 | Optimized Magnetization Decay Correction of Hyperpolarized 129Xe Ventilation Images Using Radial-Keyhole | |
| Mariah L. Costa1,2, Peter J. Niedbalski3, Matthew M. Willmering1, and Zackary I. Cleveland1,2,4 | ||
1Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States, 2Biomedical Engineering, University of Cincinnati, Cincinnati, OH, United States, 3Internal Medicine, University of Kansas Medical Center, Kansas City, KS, United States, 4Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States |
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Advances in hyperpolarization (HP) technology have expanded the translation and clinical utility of HP media MR. Unfortunately, HP images suffer from artifacts and inaccuracies due to magnetization decay. To mitigate decay, we introduced a method to map magnetization dynamics via Bloch-equation modeling and keyhole reconstruction. Here we extend the approach to include optimization via uncertainty propagation. As proof-of-principle, we compared a linear and interleaved keyhole to map HP decay in digital phantoms and 129Xe ventilation images. Linear keyhole yielded uniform decay values, while interleaved keyhole generated physically improbable distributions, demonstrating the utility of analytical optimization in radial-keyhole decay correction. |
| 3796 | Simulating the impact of asymmetric geometries on apparent alveolar septal wall thickness measurements with hyperpolarized xenon-129 MRI | |
| Yiwen Qian1, Kai Ruppert1, Faraz Amzajerdian1, Yi Xin1, Hooman Hamedani1, Luis Loza1, Tahmina S Achekzai1, Ryan J Baron1, Ian F Duncan1, Stephen Kadlecek1, and Rahim R Rizi1 | ||
1University of Pennsylvania, Philadelphia, PA, United States |
||
Measurement of the apparent alveolar septal wall thickness (SWT) via chemical shift saturation recovery (CSSR) with hyperpolarized xenon-129 is emerging as a robust and sensitive technique for detecting lung disease. However, the extracted pulmonary physiological values are obtained by fitting theoretical gas uptake curves that are based on assumptions of an unrealistically symmetric alveolar anatomy to the measurement data. In this work, we investigated the impact of asymmetric septal walls on the fitting parameters using numerically simulated CSSR measurement data. Our simulations predict potentially large errors in all fitting parameters other than the total septal wall thickness. |
| 3797 | 3D Multi-slice hyperpolarized 129Xe imaging of the human brain | |
| Vira Grynko1,2, Yurii Shepelytskyi1,2, Tao Li3, Ayman Hassan4,5, Karl Granberg4, and Mitchell S. Albert2,3,5 | ||
1Chemistry and Materials Science Program, Lakehead University, Thunder Bay, ON, Canada, 2Thunder Bay Regional Health Research Institute, Thunder Bay, ON, Canada, 3Chemistry Department, Lakehead University, Thunder Bay, ON, Canada, 4Thunder Bay Regional Health Sciences Centre, Thunder Bay, ON, Canada, 5Northern Ontario School of Medicine, Thunder Bay, ON, Canada |
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Hyperpolarized (HP) 129Xe magnetic resonance imaging (MRI) of the brain can be used to evaluate cerebral perfusion. Currently, all HP 129Xe brain imaging techniques were only performed for single slice imaging. To further develop clinical applications of functional HP 129Xe brain imaging, multi-slice acquisitions are necessary. In this work, we demonstrate the capability of multi-slice human brain imaging with HP 129Xe using 3D gradient echo imaging with a Cartesian readout. This will allow further progress in various HP 129Xe functional brain imaging applications such as perfusion evaluation and hemodynamic response detection. |
| 3798 | Molecular translation in inhomogeneous field can dramatically reduce the efficiency of spin-order transfer at high field | |
| Vladislav Ivantaev1, Stephan Berner1,2,3, Henri de Maissin1, Jan-Bernd Hövener 4, Jürgen Hennig1, Dominik v. Elverfeldt1, Valerij G. Kiselev1, and Andreas B. Schmidt1,2,3 | ||
1Department of Radiology, Medical Physics, Medical Center, University of Freiburg, Faculty of Medicine, Freiburg, Germany, 2German Consortium for Cancer Research (DKTK), partner site Freiburg, Freiburg, Germany, 3German Cancer Research Center (DKFZ), Heidelberg, Germany, 4Section Biomedical Imaging, Department of Radiology, University Medical Center Schleswig-Holstein, Campus Kiel, Kiel, Germany |
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Parahydrogen induced polarization (PHIP) allows providing hyperpolarized (HP) agents for metabolic MRI within seconds and at negligible cost. Recently, we demonstrated PHIP inside of an MRI system using spin-order transfer (SOT) sequences and showed direct in-vivo administration of the agent without transport. Here, we show that molecular translational motion in the inhomogeneous field of the MRI during SOT can strongly corrupt the HP yield. While we already demonstrated signal enhancement of 13C of 40.000-fold at 7 Tesla with our method, we suggest that the HP can be further improved by a better field homogeneity and reduced motion during the SOT. |
| 3799 | The effect of 2-deoxyglucose and lactate on cell metabolism in acute myeloblastic leukemia ML-1 Cells | |
| Johanne Haahr Knudsen1 and Lotte Bonde Bertelsen1 | ||
1The MR Research Centre, Department of Clinical Medicine, The Faculty of Health Sciences, Aarhus University, Aarhus, Denmark |
||
Deoxy-D-glucose (2-DG) is a synthetic glucose analog, which inhibits the first step in the glycolysis by inhibiting the enzyme hexokinase. It has been shown to increase chemosensitivity in some cancers and to reverse glucocorticoid resistance in acute lymphoblastic leukemia. This could have potential for treatment in other leukemia diseases. The present study investigates whether hyperpolarized 13C-MR can be used to explore into the effect of 2-DG and lactate on cell metabolism in acute myeloblastic leukemia cells. |
| 3800 | Effects of Blood Oxygen Content on Longitudinal Relaxation of Hyperpolarized 13C Agents at 7 Tesla | |
| Keith Michel1, Collin Harlan1, Trevor Mitcham1, Matthew Merritt2, Richard Bouchard1, and James Bankson1 | ||
1Imaging Physics, UT MD Anderson Cancer Center, Houston, TX, United States, 2Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, United States |
||
Longitudinal relaxation time constants of hyperpolarized [1-13C]pyruvate, [13C,15N2]urea and [2-13C]dihydroxyacetone in whole bovine blood were measured via low excitation angle dynamic pulse-acquire NMR spectroscopy at 7T. A small lactate signal was produced in scans of pyruvate, corresponding to <1% of the pyruvate precursor signal. All three 13C agents demonstrated shorter T1 relaxation time constants in blood with arterial oxygen content than in blood with venous oxygenation, and the greatest oxygen-accelerated relaxation effect was observed for pyruvate. |
| 3801 | Hyperpolarized 13C Spectroscopy with Simple Slice-and-Frequency-Selective Excitation | |
| Geoffrey J. Topping1, Irina Heid2, Marija Trajkovic-Arsic3,4, Lukas Kritzner2, Martin Grashei1, Christian Hundshammer1, Maximilian Aigner1, Jason G. Skinner1, Rickmer Braren2, and Franz Schilling1 | ||
1Department of Nuclear Medicine, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany, 2Diagnostic and Interventional Radiology, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany, 3German Cancer Consortium (DKTK) and German Cancer Research Center (DKFZ), Heidelberg, Germany, 4Division of Solid Tumor Translational Oncology, German Cancer Consortium (DKTK), West German Cancer Center, University Hospital Essen, Essen, Germany |
||
A narrow-bandwidth alternating-frequency multi-frame slice-selective-excitation FID spectroscopy sequence was implemented with minimal pulse sequence modification by prescribing spatially offset slices. This sequence was used to measure hyperpolarized [1‑13C]lactate and its downstream metabolite [1‑13C]pyruvate in a xenograft rat model of human pancreatic cancer (PSN1). Broad bandwidth excitation has difficulty separating the smaller pyruvate peak from the larger peak of injected lactate, when analyzed with magnitude spectra, phased complex spectra, or spectral fitting with the AMARES algorithm, particularly for multi-frame data. Narrow bandwidth excitation spectroscopy is simpler and more consistent to analyze, by achieving the spectral separation during acquisition. |
| 3802 | Hyperpolarized 13C Imaging Using a Custom-built 13C Jacket Coil in a 3 T GE Scanner | |
| GUANNAN ZHANG1, Kofi Deh1, Avigdor Leftin2, and Kayvan R. Keshari1,3 | ||
1Memorial Sloan Kettering Cancer Center, New York, NY, United States, 2GE Healthcare, New York, NY, United States, 3Weill Cornell Graduate School, New York, NY, United States |
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Hyperpolarized MRI using [1-13C] pyruvate is a novel technique that has been safely performed in humans for cancer studies. Here, we present preliminary work on acquiring dynamics of hyperpolarized [1-13C] pyruvate images using a custom-built 13C jacket coil, demonstrating the applicability of the method to image patients with metastatic cancer in the abdomen. The jacket coil provides coverage and RF excitation over the whole abdominal area, allowing to detect the spread of the metastatic cancer. The hyperpolarized 13C images acquired by a spiral sequence show a good quality, demonstrating the feasibility of the method for future hyperpolarization studies in patients. |
| 3803 | Slowing T1 relaxation of hyperpolarized [2-13C]pyruvate with deuterium enrichment | |
| Albert P Chen1, Kayvan R Keshari2, and Charles H Cunningham3 | ||
1GE Healthcare, Toronto, ON, Canada, 2Radiology, Memorial Sloan Kettering Cancer Center, New York, NY, United States, 3Physical Sciences, Sunnybrook Research Institute, Toronto, ON, Canada |
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The effect of deuterium enrichment on T1 relaxation was investigated for hyperpolarized [2-13C]pyruvate. The T1 increased by 10s at 3T with deurterium enrichment on the sample molecule. The T1 further increased by almost 30s when the hyperpolarized sample was dissolved using D2O instead of H2O. Deuterium enrichment of the substrate and the dissolution media has the potential to significantly increase the available non-equilibrium polarization available at the time of injection for dissolution DNP experiments. |
| 3804 | Hyperpolarized in-vivo Metabolic Imaging at 14.1T: dDNP Cryogenic Insert Redesign and Implementation | |
| Thanh Phong Lê1,2, Andrea Capozzi2,3, and Jean-Noël Hyacinthe1,4 | ||
1Geneva School of Health Sciences, HES-SO University of Applied Sciences and Arts Western Switzerland, Geneva, Switzerland, 2Laboratory of Functional and Metabolic Imaging, EPFL (Swiss Federal Institute of Technology in Lausanne), Lausanne, Switzerland, 3Department of Health Technology, Center for Hyperpolarization in Magnetic Resonance, Technical University of Denmark, Kongens Lyngby, Denmark, 4Image Guided Intervention Laboratory, University of Geneva (UNIGE), Geneva, Switzerland |
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Hyperpolarized MR studies of localized animal disease models, specifically our studies of cerebral metabolism after transient ischemia in a mouse model of stroke, are greatly improved by implementation of spatially resolved measurements. The latter allows unfolding specific metabolic alterations in core, penumbra and peripheral tissues taking place after ischemia. To achieve higher specificity, the performances of a DNP polarizer were improved by installing a custom fluid path dissolution system to achieve higher polarization levels. In parallel, we implemented a dynamic spiral acquisition sequence to enable time-resolved MR metabolic imaging. Herein, we present our preliminary in-vivo proof of principle. |
| 3805 | Dramatic Effect of Pulse Length and Bandwidth on the Efficiency of Pulsed Spin-Order-Transfer Sequences at High Field. | |
| Henri de Maissin1, Stephan Berner2, Vladislav Vladislav Ivantaev3, Jan Hövener4, Jürgen Hennig5, Dominik von Elverfeldt5, and Andreas Schmidt6 | ||
1Radiology, Uniiklinik Freiburg, Freiburg, Germany, 2radiology, Uniklinik Freiburg, Freiburg, Germany, 3radiology, Uniklinik freiburg, freiburg, Germany, 4hyperpolarization, Kiel university, Kiel, Germany, 5radiology, Uniklinik Freiburg, freiburg, Germany, 6Radiology, Uniklinik Freiburg, freiburg, Germany |
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Para-Hydrogen Induced Polarization (PHIP) is a promising cost- and time-efficient technique for highly-sensitive metabolic MRI. We recently demonstrated PHIP with 13C-polarizations of 25% inside MRI systems at high field using spin-order transfer (SOT) sequences. Here, we show that SOT is extremely sensitive to limited proton-RF bandwidth available in MRI setups. This effect is crucial for hyperpolarization of metabolic agents like acetate and pyruvate; and for PHIP in human MRI setups, dedicated hardware may be required. Still, high-field PHIP is promising as the setup is inexpensive and simple and requires no transport of the agents to the MRI system is needed. |
| 3806 | Effect of Radical Concentration on the Hyperpolarization of Silicon Nanoparticles using Dynamic Nuclear Polarization | |
| Catriona H.E. Rooney1, Jack J.J.J. Miller1,2,3, and Damian J. Tyler1,3 | ||
1Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, United Kingdom, 2Department of Physics, University of Oxford, Oxford, United Kingdom, 3Oxford Centre for Clinical Magnetic Resonance Research, University of Oxford, Oxford, United Kingdom |
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Silicon nanoparticles (SiNPs) retain enhanced polarization for several hours following hyperpolarization due to their long nuclear T1 relaxation time and are therefore attractive candidates for use as MRI contrast agents. However, “bare” SiNPs show low signal enhancement and require the addition of exogenous radicals to reach sufficient signal enhancements for MRI. Here, the addition of two radicals (Finland trityl and TEMPO) and the effect of their concentration on SiNP build-up and decay properties were investigated. Optimising SiNP polarization characteristics is necessary if their clinical translation as targeted hyperpolarized contrast agents is to be achieved. |
| 3807 | Early detection of Pancreatic Cancer by merging Hyperpolarized Magnetic Resonance and Artificial Intelligence | |
| José Santiago Enriquez1,2, Shivanand Pudakalakatti1, Prasanta Dutta1, Florencia McAllister2,3, and Pratip Bhattacharya1,2 | ||
1Cancer Systems Imaging, UT MD Anderson Cancer Center, Houston, TX, United States, 2UT MD Anderson UT Health GSBS, Houston, TX, United States, 3Clinical Cancer Prevention, UT MD Anderson Cancer Center, Houston, TX, United States |
||
Early detection and prevention of pancreatic cancer is a modern-day challenge and there is an unmet need for non-invasive imaging markers that help identify the aggressive sub-type(s) of pancreatic ductal adenocarcinoma (PDAC) at diagnosis Our objective is to address this knowledge gap by combining hyperpolarized metabolic imaging with Artificial Intelligence (AI). |
| 3808 | Setup of a cryogen-free DNP polarizer in a preclinical imaging lab | |
| Arianna Ferrari1, Josh Philipp Peters1, Mariia Anikeeva1, Frowin Ellermann1, Andrey Pravdivtsev1, Kolja Them1, and Jan-Bernd Hövener1,2 | ||
1SBMI Rad. UKSH, Kiel, Germany, 2Emmy Noether Group Molecular and Metabolic MRI - M3, Freiburg, Germany |
||
The setup of a cryogen-free device for dissolution dynamic nuclear polarization (dDNP) in an imaging facility is described. Fully automated procedures were used to calibrate the system and to perform hyperpolarization of pyruvic acid. Polarizations exceeding 30 % were achieved routinely within an experiment duration of less than an hour. Pitfalls are discussed and solutions proposed. |
| 3809 | Accelerated hyperpolarized 13C MRI using 23Na coil sensitivity mapping, proof of concept | |
| James T. Grist1,2,3, Juan Diego Sanchez4, Nikolaj Bøgh5, Esben Søvsø Szocska Hansen5, Jan Henrik Ardenkjær-Larsen6, Damian J. Tyler1,2, and Christoffer Laustsen5 | ||
1Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom, 2Oxford Centre for Magnetic Resonance, University of Oxford, Oxford, United Kingdom, 3Radiology, Oxford NHS Foundation Trust, Oxford, United Kingdom, 4Health Technology, Danish Technical University, Copenhagen, Denmark, 5Aarhus University, Aarhus, Denmark, 6Danish Technical University, Copenhagen, Denmark |
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Multi-channel acceleration of hyperpolarised 13C MRI is hindered by a lack of prior coil sensitivity profile knowledge. Here we harness a 13C tuned flexible multi-channel array to provide subject specific coil sensitivity measurements from 23Na and subsequent SENSE reconstruction of under-sampled hyperpolarised imaging data. |
| 3810 | Simulating the Effects of Diffusion on Hyperpolarized [1-13C]-Pyruvate Signal Evolution | |
| Reshmi J. S. Patel1, Collin J. Harlan1, and James A. Bankson1,2 | ||
1Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, United States, 2The University of Texas MD Anderson Cancer Center UT Health Graduate School of Biomedical Sciences, Houston, TX, United States |
||
Hyperpolarized [1-13C]-pyruvate MRI is an emerging imaging method that offers unprecedented spatiotemporal resolution for monitoring tumor metabolism in vivo. To establish a robust imaging biomarker, we must characterize phenomena that may modulate the apparent conversion rate of pyruvate into lactate (kpl). We sought to investigate the potential effect of diffusion on pyruvate-to-lactate conversion. HP signal evolution, as calculated by finite-difference time domain simulation of a 2D tissue model, was fit to a two-compartment pharmacokinetic model. Results indicate for low intracellular kpl, diffusion has a minimal impact, but pyruvate diffusion can reduce the apparent rate of conversion at high intracellular kpl. |
| 3965 | Asymmetric Susceptibility Tensor Imaging | |
| Steven Cao1, Jingjia Chen1, Hongjiang Wei2, and Chunlei Liu1 | ||
1UC Berkeley, Berkeley, CA, United States, 2Shanghai Jiao Tong University, Shanghai, China |
||
Susceptibility Tensor Imaging (STI) is a recently developed technique that uses phase data to solve for the underlying susceptibility tensor of the tissue. While STI has the potential for early diagnosis of many diseases including Parkinson’s and Alzheimer’s, it suffers from low image quality. From physics, the susceptibility tensor can be shown to be symmetric, so current approaches impose a symmetry constraint during inversion. We propose an inversion algorithm without this constraint, and instead enforce symmetry post-inversion by decomposing the result into symmetric and antisymmetric parts. We justify this approach empirically by comparing reconstructions of mouse brain and kidney data. |
| 3966
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High angular resolution susceptibility and diffusion imaging in post mortem chimpanzee brain: Tensor characteristics and similarities | |
| Dimitrios G. Gkotsoulias1, Riccardo Metere2, Yanzhu Su1, Cornelius Eichner1, Torsten Schlumm1, Roland Müller1, Alfred Anwander1, Toralf Mildner1, Carsten Jäger1, André Pampel1, Catherine Crockford3,4, Roman Wittig3,4, Liran Samuni 4,5, Kamilla Pleh 6, Chunlei Liu7, and Harald E. Möller1 | ||
1Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany, 2Donders Institute for Brain, Cognition and Behaviour, Nijmegen, Netherlands, 3Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany, 4Tai Chimpanzee Project, Centre Suisse de Recherches Scientifiques en Cote d'Ivoire, Abidjan, Cote D'ivoire, 5Department of Human Evolutionary Biology, Harvard University, Cambridge, MA, United States, 6Project Group Epidemiology of Highly Pathogenic Microorganisms, Robert Koch Institute, Berlin, Germany, 7EECS, UC Berkeley, Berkeley, CA, United States |
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We present a ‘high angular resolution’ approach to susceptibility tensor imaging (STI) consisting of susceptibility-weighted acquisitions at 60 independent orientations in post- mortem chimpanzee brain. The derived susceptibility tensor and metrics are compared with the corresponding diffusion tensor-derived metrics and single-orientation quantitative susceptibility mapping (QSM) results. A preliminary approach to assess the voxel-wise relationship of the two tensors in white matter is presented: using machine learning strategies, an effort to estimate the susceptibility tensor from the diffusion tensor and minimum single-orientation QSM data in selected regions of interest was made. |
| 3967
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Rotation-Free Mapping of Magnetic Tissue Properties in White Matter | |
| Anders Dyhr Sandgaard1, Valerij G. Kiselev2, Noam Shemesh3, and Sune Nørhøj Jespersen1,4 | ||
1Department of Clinical Medicine, Center for Functionally Integrative Neuroscience, Aarhus University, Aarhus, Denmark, 2Medical Physics, Department of Radiology, Faculty of Medicine, University of Freiburg, Freiburg, Germany, 3Champalimaud Neuroscience Programme, Champalimaud Centre for the Unknown, Lisbon, Portugal, 4Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark |
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Mapping tissue magnetic properties may be a useful tool for understanding basic disease mechanism in neurodegenerative diseases. However, magnetic properties depend on the arrangement of magnetic susceptibility on all scales, including the microstructure, and typically require impractical sample rotations for robust estimation. By modeling white matter fibers as a system of cylinders, here we show that the first cumulant $$$\langle\Omega\rangle$$$ of the FID signal can be obtained without the need for sample rotation, by utilizing the fiber orientation distribution function estimated by diffusion imaging. |
| 3968
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Magnetic susceptibility source separation: validation with Monte-Carlo simulation & application to human brain with histological comparison | |
| Hyeong-Geol Shin1, Young Hyun Yun2, Seong Ho Yoo2, Sehoon Jung3, Sunhye Kim3, Hyung Jin Choi 2, and Jongho Lee1 | ||
1Seoul National University, Seoul, Korea, Republic of, 2Seoul National University College of Medicine, Seoul, Korea, Republic of, 3Research Institute of Industrial Science and Technology, Pohang, Korea, Republic of |
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We validate the magnetic susceptibility source separation method, which is recently proposed to separate paramagnetic (e.g., iron) and diamagnetic sources (e.g., myelin), by performing Monte-Carlo simulation. Then, the method is applied to ex-vivo and in-vivo human brains and compared to histology. In the simulation, we show the method successfully estimates the paramagnetic and diamagnetic susceptibility concentrations. When compared to histology, the ex-vivo and in-vivo results demonstrated that the positive and negative susceptibility maps from the method highly correspond to the iron and myelin distributions, respectively, proving its feasibility as a tool to map iron and myelin distributions in the brain. |
| 3969 | Validating DECOMPOSE QSM with temperature variant ex vivo brainstem imaging experiments | |
| Jingjia Chen1, Khallil Taverna Chaim2, Maria Concepción García Otaduy2, and Chunlei Liu1,3 | ||
1Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, CA, United States, 2LIM44, Instituto e Departamento de Radiologia, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, Brazil, 3Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA, United States |
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A model and corresponding solver for estimating sub-voxel paramagnetic and diamagnetic susceptibility components are validated based on the temperature dependence of magnetic susceptibility. Two pieces of brainstem sample were scanned under various temperature conditions to test the properties of the separated paramagnetic and diamagnetic components. |
| 3970 | Studying magnetic susceptibility, microstructural compartmentalisation and chemical exchange in a formalin-fixed, whole-brain specimen | |
| Kwok-Shing Chan1, Jeroen Mollink2, Jenni Schulz1, Anne-Marie van Cappellen van Walsum2, and José P. Marques1 | ||
1Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, Netherlands, 2Department of Medical Imaging, Anatomy, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, Netherlands |
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In this work, we study the feasibility of using formalin-fixed post-mortem specimen to investigate MRI phase contrast in brain tissue. Despite the magnetic susceptibility maps derived from in vivo and ex vivo imaging share similar contrasts, the non-susceptibility contributions on measured fields of ex vivo sample were clear affected by fixation process, and we found its microstructural compartmentalisation effect are also greatly reduced. Therefore, extra care has to be taken to directly translate ex vivo findings to in vivo applications. |
| 3971 | Robust Masking Techniques for Multi-Echo Quantitative Susceptibility Mapping | |
| Ashley Stewart1,2, Simon Daniel Robinson2,3, Kieran O'Brien1,2,4, Jin Jin1,2,4, Georg Widhalm5, Gilbert Hangel3,5, Angela Walls6, Jonathan Goodwin7,8, Korbinian Eckstein3, Markus Barth1,2,9, and Steffen Bollmann1,2,9 | ||
1Centre for Innovation in Biomedical Imaging Technology, University of Queensland, Brisbane, Australia, 2Centre for Advanced Imaging, University of Queensland, Brisbane, Australia, 3High Field MR Center, Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, Vienna, Austria, 4Siemens Healthcare Pty Ltd, Brisbane, Australia, 5Department of Neurosurgery, Medical University of Vienna, Vienna, Austria, 6Clinical & Research Imaging Centre, South Australian Health and Medical Research Institute, Adelaide, Australia, 7Department of Radiation Oncology, Calvary Mater Hospital, Newcastle, Australia, 8School of Mathematical and Physical Science, University of Newcastle, Newcastle, Australia, 9School of Information Technology and Electrical Engineering, University of Queensland, Brisbane, Australia |
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Quantitative Susceptibility Mapping (QSM) is a post-processing technique applied to gradient-echo phase data. QSM generally requires a signal mask to identify reliable phase values before reconstruction. Most QSM pipelines do not include masking procedures, and often suggest masking techniques that introduce artefacts, work only in the human brain, and lose critical information, especially near strong susceptibility sources. We propose two novel echo-dependent masking strategies and find that they significantly reduce streaking artefacts, particularly surrounding strong sources and tissue boundaries in multi-echo data. Our techniques are open-source and implemented in a new framework for automated, scalable, and robust QSM processing. |
| 3972 | Quantitative susceptibility mapping in water–fat regions using in-phase echoes introduces significant quantification bias | |
| Christof Boehm1, Maximilian N. Diefenbach1,2, Sophia Kronthaler1, Jakob Meineke3, Kilian Weiss4, Marcus R. Makowski1, and Dimitrios C. Karampinos1 | ||
1Department of Diagnostic and Interventional Radiology, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany, 2Division of Infectious Diseases and Tropical Medicine, University Hospital, LMU Munich, Munich, Germany, 3Philips Research Lab, Hamburg, Germany, 4Philips Healthcare, Hamburg, Germany |
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Gradient echo imaging using in-phase echoes has been proposed to reduce the field-map estimation in water–fat regions to a convex nonlinear least squares problem. However, it is known that the fat spectrum is complex and the definition of in-phase echo times remains problematic. In this work, the in-phase assumption is compared to standard water–fat imaging with respect to field- and quantitative susceptibility-mapping. The in-phase assumption is shown to be associated with quantification bias when subsequently estimating the field map and magnetic susceptibility in the spine, the liver and the breast. |
| 3973 | Investigating the Effect of Flow Compensation Schemes and Processing Pipelines on the Accuracy of Venous Quantitative Susceptibility Mapping | |
| Ronja C. Berg1, Christine Preibisch1, Claus Zimmer1, David L. Thomas2,3, Karin Shmueli4, and Emma Biondetti5 | ||
1School of Medicine, Department of Neuroradiology, Technical University of Munich, Munich, Germany, 2Dementia Research Centre, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom, 3Wellcome Centre for Human Neuroimaging, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom, 4Department of Medical Physics and Biomedical Engineering, University College London, London, United Kingdom, 5Institut du Cerveau – ICM, INSERM U 1127, CNRS UMR 7225, Sorbonne Université, Paris, France |
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Venous quantitative susceptibility mapping (QSM) enables quantification of venous oxygenation. Flow-compensated acquisition is generally recommended for venous QSM, although its effect on the accuracy of venous susceptibility values has not been systematically evaluated. Moreover, QSM processing methods tend to be optimized for brain parenchyma tissues rather than veins. Here, we compared five different acquisition protocols (incorporating distinct flow compensation schemes) and six QSM processing methods in ten healthy volunteers. We found that venous susceptibility values depend strongly on the QSM pipeline (effect size ηp2=0.861) and much less on acquisition parameters including flow compensation (effect size ηp2=0.016). |
| 3974 | Reproducibility of R2* and quantitative susceptibility mapping in deep grey matter at 3T: Cross-vendor non-harmonized protocol study | |
| Nashwan Naji1, M. Louis Lauzon2,3, Peter Seres1, Emily Stolz1, Richard Frayne2,3, Catherine Lebel4, Christian Beaulieu1, and Alan H. Wilman1 | ||
1Department of Biomedical Engineering, University of Alberta, Edmonton, AB, Canada, 2Departments of Radiology and Clinical Neurosciences, Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada, 3Seaman Family MR Research Centre, Foothills Medical Centre, Calgary, AB, Canada, 4Department of Radiology, Alberta Children’s Hospital Research Institute and Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada |
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R2* and QSM provide noninvasive ways to measure iron concentration in human brain. Performing multi-center studies help exploring wider demographical and pathological conditions. However, data pooled from multiple sites typically contain local acquisition sequence variations. In this study, the reproducibility of R2* and QSM at 3T are evaluated in 21 healthy adults (“traveling phantoms”) scanned 2x per site using independently site-optimized sequences from three sites and two scanner vendors. Mean R2* and susceptibility measurements in four deep grey matter structures were found to be highly correlated (r2 ≥ 0.98) and reproducible with SD of 1.2 s-1 and 4.1 ppb, respectively. |
| 3975 | Deep learning based quantitative susceptibility mapping (QSM) in the presence of fat by using synthetically generated multi-echo phase data | |
| Jannis Hanspach1, Aurel Jolla1, Michael Uder1, Bernhard Hensel2, Steffen Bollmann3, and Frederik Bernd Laun1 | ||
1Institute of Radiology, University Hospital Erlangen, Friedrich‐Alexander‐Universität Erlangen‐Nürnberg (FAU), Erlangen, Germany, 2Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Center for Medical Physics and Engineering, Erlangen, Germany, 3University of Queensland, Brisbane, Australia, School of Information Technology and Electrical Engineering, Brisbane, Australia |
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Deep Learning reconstruction methods are increasingly investigated in Quantitative Susceptibility Mapping (QSM). In this work, we applied a UNET to reconstruct susceptibility maps in the presence of fat from unwrapped phase maps. The network was trained using synthetically generated multi-echo phase data and does not require explicit masking for the background field correction. Our results show that the proposed approach is well-suited to rapidly reconstruct high quality susceptibility maps in the presence of fat (e.g., outside the central nervous system) in in vivo data. |
| 3976
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Necessity for a common dataset for a fair comparison between deep neural networks for QSM | |
| Chungseok Oh1, Woojin Jung1, Hwihun Jeong1, and Jongho Lee1 | ||
1Seoul National University, Seoul, Korea, Republic of |
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We demonstrated that at least two conditions are required for a fair comparison between deep neural networks for dipole inversion: First, test data need to have the same characteristics as training data. Second, hyperparameter tuning should be performed if training dataset is changed. Our study implies that a common dataset is necessary for a fair comparison of deep neural networks for QSM. |
| 3977 | Generalization of deep learning-based QSM by expanding the diversity of spatial gradient in training data | |
| Woojin Jung1, Steffen Bollmann2, Se-Hong Oh3, Hyeong-geol Shin1, Sooyeon Ji1, and Jongho Lee1 | ||
1Department of Electrical and Computer Engineering, Seoul National University, Seoul, Korea, Republic of, 2The University of Queensland, Brisbane, Australia, 3Biomedical Engineering, Hankuk University of Foreign Studies, Yongin, Korea, Republic of |
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In this work, the effect of spatial gradients in the training data on deep learning-based QSM is explored. We observe that deep learning-based QSM underestimates the susceptibility values when spatial gradients differ between training and test data. For demonstration, three types of networks were trained by using different spatial gradients of training images and evaluated on test data with varying spatial gradients. The results indicate that expanding the spatial gradient distribution of training data improves the performance of deep learning-based QSM. Furthermore, we demonstrate that augmenting spatial gradients may improve deep-learning based QSM to work for various image resolutions. |
| 3978 | NeXtQSM - A complete deep learning pipeline for data-consistent quantitative susceptibility mapping trained with synthetic data | |
| Francesco Cognolato1,2, Kieran O’Brien2,3, Jin Jin2,3, Simon Robinson4,5, Markus Barth1,2,6, and Steffen Bollmann1,2,6 | ||
1Centre for Advanced Imaging, The University of Queensland, Brisbane, Australia, 2ARC Training Centre for Innovation in Biomedical Imaging Technology, The University of Queensland, Brisbane, Australia, 3Siemens Healthcare Pty Ltd, Brisbane, Australia, 4High Field MR Center, Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, Vienna, Austria, 5Department of Neurology, Medical University of Graz, Graz, Austria, 6School of Information Technology and Electrical Engineering, The University of Queensland, Brisbane, Australia |
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Deep learning based quantitative susceptibility mapping has shown great potential in recent years, outperforming traditional non-learning approaches in speed and accuracy in many applications. Here we aim to overcome the limitations of in vivo training data and model-agnostic deep learning approaches commonly used in the field. We developed a new synthetic training data generation method that enables the background field correction and a data-consistent solution of the dipole inversion to be learned using a variational network in one pipeline. NeXtQSM is a complete deep learning based pipeline for computing robust, fast and accurate quantitative susceptibility maps. |
| 3979 | Total Deep Variation Regularization for Improved Iterative Quantitative Susceptibility Mapping (TDV-QSM) | |
| Carlos Milovic1, Jose Manuel Larrain2,3, and Karin Shmueli1 | ||
1Department of Medical Physics and Biomedical Engineering, University College London, London, United Kingdom, 2Department of Electrical Engineering, Pontificia Universidad Catolica de Chile, Santiago, Chile, 3Biomedical Imaging Center, Pontificia Universidad Catolica de Chile, Santiago, Chile |
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Quantitative Susceptibility Mapping (QSM) is an ill-posed inverse problem. Traditionally, it is solved by minimization of a functional. Regularization terms may be interpreted as a denoising process. Many state-of-the-art methods are based on Total Variation regularization terms, with great success. With the advent of Deep Learning, new regularization strategies have been derived from training datasets. Total Deep Variation (TDV) is a recently proposed technique, showing impressive results. We applied a pre-trained TDV network as a denoising step in an iterative QSM solver. Results show improved error metrics for synthetic brain phantoms and enhanced in-vivo reconstructions, compared to Total-Variation-based algorithms. |
| 3980 | Exploring domain adaption for deep neural network trained QSM | |
| JUAN LIU1 and Kevin Koch2 | ||
1Yale University, New Haven, CT, United States, 2Medical College of Wisconsin, Milwaukee, WI, United States |
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We aim to address the domain adaption problem of neural networks for QSM reconstruction which are learned from synthetic data while applied on real data. To address the unsupervised domain adaption, we apply domain-specific batch normalization layers in convolutional neural networks while allowing them to share all other model parameters. The proposed method is evaluated on multiple orientation datasets and single-orientation QSM datasets. Compared withTKD, MEDI, and DL-based method first training on synthetic datasets then model-based fine-tuning on real datasets, the proposed method achieved better performance. |
| 3981 | HANDI: Hessian Accelerated Nonlinear Dipole Inversion for rapid QSM | |
| Christian Kames1,2, Jonathan Doucette1,2, and Alexander Rauscher1,2,3 | ||
1UBC MRI Research Centre, The University of British Columbia, Vancouver, BC, Canada, 2Department of Physics and Astronomy, The University of British Columbia, Vancouver, BC, Canada, 3Department of Pediatrics, The University of British Columbia, Vancouver, BC, Canada |
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We propose an extension of nonlinear dipole inversion (NDI), a first order method for solving the nonlinear formulation of the dipole inversion in quantitative susceptibility mapping (QSM), by using a second order method to increase the convergence rate of the minimization. The proposed method, Hessian Accelerated Nonlinear Dipole Inversion (HANDI), is shown to require fewer iterations than NDI, resulting in reconstruction times of a few seconds, more than 10x faster than NDI, without sacrificing accuracy. We further propose a learned proximal Newton method (HANDINet) and show that it outperforms learned variational networks based on NDI and standard dipole deconvolution minimizations. |
| 3982 | Automatic, Non-Regularized Nonlinear Dipole Inversion for Fast and Robust Quantitative Susceptibility Mapping | |
| Carlos Milovic1 and Karin Shmueli1 | ||
1Department of Medical Physics and Biomedical Engineering, University College London, London, United Kingdom |
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Quantitative Susceptibility Mapping (QSM) is an ill-posed inverse problem often solved by regularization: minimizing a functional until it converges. This is usually time-consuming, requiring fine-tuning of several parameters by many repetitions of the whole optimization solver. Nonlinear Dipole Inversion is a QSM method that solves a nonlinear Tikhonov-regularized functional with a gradient descent solver. We show that stopping this method early provides optimal results, largely independent of the regularization weight. Here, we propose a non-regularized nonlinear conjugate gradient solver with a new stopping criterion based on analysing susceptibility map spatial frequency coefficients to achieve fast, parameter-free and automatic QSM. |
| 3983 | Improving Quantitative Susceptibility Mapping reconstructions via non-linear Huber loss data fidelity term (Huber-QSM) | |
| Mathias Gabriel Lambert1,2,3, Carlos Milovic4, and Cristian Tejos1,2,3 | ||
1Department of Electrical Engineering, Pontificia Universidad Católica de Chile, Santiago, Chile, 2Biomedical Imaging Center, Pontificia Universidad Católica de Chile, Santiago, Chile, 3Millennium Nucleus for Cardiovascular Magnetic Resonance, Santiago, Chile, 4Department of Medical Physics and Biomedical Engineering, University College London, London, United Kingdom |
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Compared to L2-norm based QSM reconstructions, methods based on L1-norm data consistency are less prone to artifact generation caused by phase inconsistencies (e.g. unwrapping artifacts, intravoxel dephasing). However, L2-norm methods present better denoising performance in high SNR regions. Here, we present a QSM algorithm that combines the strengths of the L1 and L2 norms, using Huber's loss function as the data consistency term. Simulations and in vivo reconstructions showed enhanced performance, with superior artifact suppression capabilities of our proposed method. |
| 3984 | Non-regularized Dipole Inversion with streaking suppression via L1-norm optimization | |
| Mathias Gabriel Lambert1,2,3, Cristian Tejos1,2,3, and Carlos Milovic4 | ||
1Department of Electrical Engineering, Pontificia Universidad Católica de Chile, Santiago, Chile, 2Biomedical Imaging Center, Pontificia Universidad Católica de Chile, Santiago, Chile, 3Millennium Nucleus for Cardiovascular Magnetic Resonance, Santiago, Chile, 4Department of Medical Physics and Biomedical Engineering, University College London, London, United Kingdom |
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Non-regularized QSM reconstructions are feasible by stopping gradient descent methods before they diverge. These methods consume less computation time, while avoiding the time required for parameter selection. In this work we present a linear dipole inversion method without regularization that uses the L1-norm in a proximal step to prevent streaking propagation and present more robustness against phase outliers. Compared to the Nonlinear Dipole Inversion method, our implementation achieved lower RMSE scores in phantom experiments and in vivo reconstructions with fewer artifacts. |
| 3985 | Quantitative susceptibility mapping MRI of brain iron and PET of β-amyloid predict cognitive decline during aging | |
| Lin Chen1,2, Anja Soldan3, Kenichi Oishi1, Andreia Faria1, Marilyn Albert3, Peter van Zijl1,2, and Xu Li1,2 | ||
1Department of Radiology and Radiological Sciences, Johns Hopkins University, Baltimore, MD, United States, 2F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States, 3Department of Neurology, Johns Hopkins University, Baltimore, MD, United States |
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We investigated associations of brain volume, iron levels as measured by QSM-MRI, and β-amyloid plaque load as measured by 11C-PiB PET imaging on prospective cognitive trajectories, measured using a global and domain-specific cognitive composite scores (e.g., episodic memory, executive function, visuospatial processing and language) in cognitively normal older adults with maximum follow-up of 5 years. Greater volume of multiple cortical and subcortical brain regions was strongly associated with the rate of cognitive decline. Associations between brain iron and β-amyloid and longitudinal cognitive decline were weaker, with brain iron in the basal ganglia and entorhinal cortex predicting global decline. |
| 3986 | Prediction of Amyloid-β Deposition Using Multiple Regression Analysis of Quantitative Susceptibility Mapping | |
| Ryota Sato1, Kohsuke Kudo2, Niki Udo3, Masaaki Matsushima4, Ichiro Yabe4, Akinori Yamaguchi2, Makoto Sasaki5, Masafumi Harada6, Noriyuki Matsukawa7, Tomoki Amemiya1, Yasuo Kawata1, Yoshitaka Bito1, Hisaaki Ochi1, and Toru Shirai1 | ||
1Healthcare Business Unit, Hitachi, Ltd., Tokyo, Japan, 2Department of Diagnostic Imaging, Hokkaido University Graduate School of Medicine, Hokkaido, Japan, 3Department of Psychiatry, Hokkaido University Graduate School of Medicine, Hokkaido, Japan, 4Department of Neurology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Hokkaido, Japan, 5Institute for Biomedical Sciences, Iwate Medical University, Iwate, Japan, 6Department of Radiology, Tokushima University, Tokushima, Japan, 7Department of Neurology, Nagoya City University, Aichi, Japan |
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For early diagnosis of Alzheimer’s disease, we created and evaluated a prediction method of amyloid β deposition based on multiple regression analysis of quantitative susceptibility mapping. A multiple regression model to predict standard uptake values (SUVs) of amyloid PET was constructed based on susceptibilities in 47 brain regions with the constraint Aβ deposition and susceptibility being positively correlated. The correlation coefficients between true and predicted SUVs were increased by incorporating the constraint, and the area under the receiver operating characteristics curve to predict Aβ positivity was 70%. The results suggest that the model could predict Aβ positivity at moderate accuracy. |
| 3987 | Quantifying iron deposition in Multiple System Atrophy via multi-echo Quantitative Susceptibility Mapping | |
| Marta Lancione1,2, Matteo Cencini2,3, Mauro Costagli3,4, Graziella Donatelli2,5, Michela Tosetti2,3, Claudio Pacchetti6, Pietro Cortelli7,8, and Mirco Cosottini5 | ||
1IMT School for Advanced Studies Lucca, Lucca, Italy, 2IMAGO7 Foundation, Pisa, Italy, 3IRCCS Stella Maris, Pisa, Italy, 4Department of Neuroscience, Rehabilitation, Ophtalmology, Genetics, Maternal and Child Sciences (DINOGMI), University of Genova, Genova, Italy, 5Azienda Ospedaliero-Universitaria Pisana, Pisa, Italy, 6Parkinson and Movement Disorder Unit, IRCCS Mondino Foundation, Pavia, Italy, 7Department of Biomedical and NeuroMotor Sciences, University of Bologna, Bologna, Italy, 8Clinica Neurologica, IRCCS Istituto delle Scienze Neurologiche di Bologna, Bologna, Italy |
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In this work we quantified iron deposition in gray matter nuclei in a cohort of MSA patients with parkinsonian and cerebellar phenotypes using Quantitative Susceptibility Mapping (QSM). As it captures different tissues contribution depending on TE, we performed an ROI-based histogram analysis on susceptibility maps computed at each TE of a multi-echo GRE sequence. We observed significant differences among groups in several ROIs, such as putamen, globus pallidus, caudate nucleus, substantia nigra and dentate nucleus. The area under the ROC curve was higher for short TEs suggesting that short-TE QSM enhances diagnostic performances in the presence of strong susceptibility sources. |
| 3988 | Clinical correlations of iron-rich deep grey matter of MS patients | |
| Ibrahim Khormi1,2, Oun Al-iedani1,2, Amir Fazlollahi2,3, Bryan Paton2,4, Jeannette Lechner-Scott2,4,5, Abdulaziz Alshehri1,2, Kieran O'Brien6,7, Steffen Bollmann8, Rishma Vidyasagar9, Scott Ayton9, Anne-Louise Ponsonby9,10, and Saadallah Ramadan1,2 | ||
1School of Health Sciences, University of Newcastle, Newcastle, Australia, 2Hunter Medical Research Institute, Newcastle, Australia, 3CSIRO Health and Biosecurity, Brisbane, Australia, 4University of Newcastle, Newcastle, Australia, 5John Hunter Hospital, Newcastle, Australia, 6Siemens Healthcare Pty Ltd, Brisbane, Austria, 7ARC Training Centre for Innovation in Biomedical Imaging Technology, The University of Queensland, Brisbane, Australia, 8The University of Queensland, Brisbane, Australia, 9The Florey Institute of Neuroscience & Mental Health, Parkville, Australia, 10Murdoch Children's Research Institute, Royal Children's Hospital, University of Melbourne, Melbourne, Australia |
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This novel study compared quantitative magnetic susceptibility signal of deep grey matter (DGM) structures in the MS brain. We evaluated the QSM metrics in selected deep grey matter regions in 5 RRMS patients and 9 matched HCs. The STI suite software package was used for QSM image reconstruction. Compared to a reference region in HCs, a significant susceptibility change was detected in most DGM regions showing statistically significant RRMS cohort differences. QSM metrics in caudate showed strong correlations with depression scores, while pallidum and thalamus correlated significantly with anxiety. While results are limited due to small numbers, they provide the opportunity for further investigation in larger cohorts and strengthen these preliminary results. |
| 3989 | Separation of positive and negative susceptibility contrast at 7 Tesla allows for a more detailed characterization of multiple sclerosis lesions | |
| Julian Emmerich1,2, Frederik L. Sandig3, and Sina Straub1 | ||
1Division of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany, 2Faculty of Physics and Astronomy, University of Heidelberg, Heidelberg, Germany, 3Division Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany |
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Quantitative susceptibility mapping (QSM) is known for its usefulness in imaging multiple sclerosis lesions. However, the co-occurrence of demyelination and iron accumulation due to the underlying inflammatory processes limit QSM from truthfully representing histology-like information as phase effects from positive and negative susceptibility sources within the same voxel cancel out in QSM. Here, it is shown that the separation of positive and negative susceptibility sources provides additional information to characterize susceptibility lesions. |
| 3990 | Quantitative susceptibility mapping in the infant brain diagnosed with congenital heart disease | |
| Zungho Zun1,2,3,4, Kushal Kapse1, Nicole Andersen1, Scott Barnett1,2,3,4, Anushree Kapse1, Kristina Espinosa1, Jessica Quistorff1, Catherine Lopez1, Jonathan Murnick1,3,4, Mary T. Donofrio2,3,5, and Catherine Limperopoulos1,2,3,4 | ||
1Division of Diagnostic Imaging and Radiology, Children's National Hospital, Washington, DC, United States, 2Division of Fetal and Transitional Medicine, Children's National Hospital, Washington, DC, United States, 3Department of Pediatrics, George Washington University, Washington, DC, United States, 4Department of Radiology, George Washington University, Washington, DC, United States, 5Division of Cardiology, Children’s National Hospital, Washington, DC, United States |
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Quantitative susceptibility mapping may be used to assess brain development in infants based on its ability to evaluate iron and myelin contents. We measured magnetic susceptibilities in healthy infants and those diagnosed with congenital heart disease (CHD) in the early postnatal period and investigated the associations with neurodevelopmental outcomes. We report significantly lower magnetic susceptibilities in white matter and temporal lobe of the CHD cohort and significant associations between magnetic susceptibility of the temporal lobe and Bayley-III language scores at 18 months. Our findings may suggest disturbed iron deposition in the temporal lobe can lead to delays in language development. |
| 3991 | Quantitative Susceptibility Mapping of Venous Vessels in Neonates With Perinatal Asphyxia | |
| Alexander Mark Weber1, Yuting Zhang2, Christian Kames3, and Alexander Rauscher1 | ||
1Pediatrics, UBC, Vancouver, BC, Canada, 2Radiology, Children’s Hospital of Chongqing Medical University, Chongqing, China, 3Physics, UBC, Vancouver, BC, Canada |
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We aimed to test whether Cerebral venous oxygen saturation (CSVO2) could be measured using quantitative susceptibility mapping (QSM) in three distinct groups: healthy term neonates, and asphyxia injured term and preterm neonates. We acquired multi-echo gradient echo MRI data in 16 neonates with perinatal asphyxia and moderate or severe hypoxic-ischemic encephalopathy (HIE) (eight term-age, eight preterm, in eight healthy term-age controls. QSM derived oxygen saturation values in preterm and term neonates agreed well with past literature. CSVO2 in preterm and term neonates with HIE, however, were not found to be significantly different from each other or healthy controls. |
| 3992 | Investigating the Effect of Positive Airways Pressure on Venous Oxygenation in Sickle Cell Anemia with Quantitative Susceptibility Mapping | |
| Russell Murdoch1, Hanne Stotesbury2, Jamie Kawadler2, Dawn Saunders2, Fenella Kirkham2, and Karin Shmueli1 | ||
1Department of Medical Physics and Biomedical Engineering, University College London, London, United Kingdom, 2Imaging and Biophysics, Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, London, United Kingdom |
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In 88 sickle cell anaemia (SCA) patients and 30 healthy controls, quantitative susceptibility mapping (QSM) showed significantly lower venous oxygen saturation (Yv) in the superior sagittal sinus of SCA patients. SCA subjects with silent cerebral infarcts (SCI) showed significantly lower Yv relative to those without SCI. 39 SCA subjects participated in a clinical study investigating the effect of auto-adjusting positive airways pressure (APAP) over a period of six months. No significant Yv differences were observed between 21 patients receiving APAP and 18 receiving standard care. In the APAP group, treatment compliance was positively correlated with increases in Yv. |
| 3993 | Validation Study of Venous Oxygenation in Internal Cerebral Vein in Patients with Sickle Cell Disease by QSM and CISSCO Method | |
| Jian Shen1, Aart Nederveen2, and John Wood1,3 | ||
1Biomedical Engineering, University of Southern California, Los Angeles, CA, United States, 2Radiology, Academic Medical Center, Amsterdam, Netherlands, 3Children's Hospital Los Angeles, Los Angeles, CA, United States |
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Brain oxygenation can be measured using either T2-based methods or magnetic susceptibility-based methods. This study validates QSM and CISSCO methods in measuring the oxygenation in the internal cerebral vein and compares the results in sickle cell disease patients, anemia subjects with normal hemoglobin and healthy controls. Both methods reveal the group difference in the oxygen saturation in the deep structures. The limitations for both methods are discussed and the explanation for the bias between the two methods is provided. |
| 3994 | Investigating the Magnetic Susceptibility of Silent Cerebral Infarcts in Sickle Cell Anaemia Using Two Different Gradient Echo Acquisitions | |
| Russell Murdoch1, Hanne Stotesbury2, Jamie Kawadler2, Dawn Saunders2, Fenella Kirkham2, and Karin Shmueli1 | ||
1Department of Medical Physics and Biomedical Engineering, University College London, London, United Kingdom, 2Imaging and Biophysics, Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, London, United Kingdom |
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Little is known about the histopathology of silent cerebral infarcts (SCI) in sickle cell anaemia (SCA). Therefore, we measured the magnetic susceptibility (χ) of SCI in 45 SCA subjects and 10 healthy controls using quantitative susceptibility mapping (QSM) calculated from two different gradient-echo (GRE) acquisitions. Significantly lower χ was measured in lesions located in the parietal lobes relative to the frontal lobe. No significant relationships with mean lesion χ were observed with subject age, lesion size or depth in white matter. Strong correlations and minimal biases were observed between mean lesion χ measured using the two GRE acquisitions. |
| 3995 | Improved Regularization for Quantitative Susceptibility Mapping of Liver Iron Overload | |
| Julia V Velikina1, Ruiyang Zhao1,2, Collin Buelo2, Alexey A Samsonov1, Scott Reeder1,2,3,4,5, and Diego Hernando1,2 | ||
1Radiology, University of Wisconsin-Madison, Madison, WI, United States, 2Medical Physics, University of Wisconsin - Madison, Madison, WI, United States, 3Biomedical Engineering, University of Wisconsin - Madison, Madison, WI, United States, 4Emergency Medicine, University of Wisconsin - Madison, Madison, WI, United States, 5Medicine, University of Wisconsin - Madison, Madison, WI, United States |
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QSM may enable accurate quantification of liver iron overload. However, QSM of the abdomen faces a number of unique challenges due to large variations in susceptibility, presence of fat, and motion, which further confound the ill-posed inverse problem. We propose an approach to optimize the use of additional information provided by CSE imaging to regularize the QSM inversion problem. We validated this approach at 3T in patients with various levels of iron overload, including assessment of test-retest repeatability. This approach resulted in significantly reduced shading artifact, improved quality of susceptibility maps, and higher repeatability of measurements. |
| 3996 | Quantitative Susceptibility Mapping of Liver Iron Overload using Deep Learning | |
| Ruiyang Zhao1,2, Collin J Buelo2, Julia V Velikina1, Steffen Bollmann3, Ante Zhu4, Scott B Reeder1,2,5,6,7, and Diego Hernando1,2 | ||
1Radiology, University of Wisconsin-Madison, Madison, WI, United States, 2Medical Physics, University of Wisconsin-Madison, Madison, WI, United States, 3School of Information Technology and Electrical Engineering, University of Queensland, Brisbane, Australia, 4GE Global Research, Niskayuna, NY, United States, 5Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, United States, 6Medicine, University of Wisconsin-Madison, Madison, WI, United States, 7Emergency Medicine, University of Wisconsin-Madison, Madison, WI, United States |
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A novel deep learning-based technique for quantitative susceptibility mapping (QSM) of liver iron overload was developed and validated. The proposed method relies on a 3D fully convolutional neural network, trained using synthetic dataset from a digital torso phantom that includes major organs. This study also included patients with iron overload who were imaged under 3T with using a single breath-hold multi-echo acquisition. Results showed promising performance and agreement with reference susceptibility measurements across a wide range of iron overload cases. |
| 3997 | Comparison of True Susceptibility Weighted Imaging (tSWI) with SWI and QSM for Intracranial Hemorrhage | |
| Ashmita De1, Derek J. Emery2, Kenneth S. Butcher3, and Alan H. Wilman1 | ||
1Department of Biomedical Engineering, University of Alberta, Edmonton, AB, Canada, 2Department of Radiology and Diagnostic Imaging, University of Alberta, Edmonton, AB, Canada, 3Division of Neurology, Department of Medicine, University of Alberta, Edmonton, AB, Canada |
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Quantitative Susceptibility Weighted Imaging or True SWI(tSWI) has been recently developed to overcome the shortcomings of SWI. SWI images are computed from filtered phase images, however, tSWI utilizes the susceptibility maps for its computation. Eight intracranial hemorrhage patients were scanned at 3T with 3D SWI sequence. Blooming effect and phase wrap artifacts that remain on SWI images of hemorrhage are removed in tSWI. tSWI provides better susceptibility weighting than magnitude within the hemorrhage and improved the texture visualization as compared Quantitative Susceptibility Mapping(QSM). Thus, tSWI can be a useful addition for hemorrhage visualization when SWI cannot provide a clear depiction. |
| 3998 | Radiomic Features on Quantitative Susceptibility Mapping Classify Amyotrophic Lateral Sclerosis Patients from Mimics | |
| Anja Samardzija1, Thanh Nguyen2, Elizabeth Sweeney2, Kailyn Lee2, Ilhami Kovanlikaya2, Yi Wang 2, Andrew Schweitzer2, and Apostolos Tsiouris2 | ||
1Electrical and Computer Engineering, Cornell University, Highlands, NJ, United States, 2Weill Cornell Medicine, New York City, NY, United States |
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We trained a Random Forest classification model to classify amyotrophic lateral sclerosis (ALS) patients from those with mimicking clinical presentations based on QSM radiomic features extracted from the primary motor cortex. In a validation set, the model has 0.8 accuracy, 0.75 specificity of 0.75 and 0.84 sensitivity, which is superior to models using the mean QSM value as cutoff with 0.59 accuracy, 0.94 specificity and 0.14 sensitivity. |
| 3999 | Quantitative susceptibility mapping in the basal ganglia of systemic lupus erythematosus patients with neuropsychiatric complaints | |
| Marjolein Bulk1, Thijs van Harten1, Boyd Kenkhuis1, Francesca Inglese1, Ingrid Hegeman1, Sjoerd van Duinen1, Ece Ercan1, Cesar Magro-Checa1,2, Jelle Goeman1, Christian Mawrin3, Mark van Buchem1, Gerda Steup-Beekman1, Tom Huizinga1, Louise van der Weerd1, and Itamar Ronen1 | ||
1Leiden University Medical Center, Leiden, Netherlands, 2Zuyderland Medical Center, Heerlen, Netherlands, 3Otto-von-Guericke University, Magdeburg, Germany |
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We explored the link between iron accumulation and neuroinflammation in basal ganglia in SLE using quantitative susceptibility mapping. We hypothesized that SLE patients, and in particular NPSLE patients would have increased numbers of activated microglia co-localizing with iron, which in turn would be reflected in increased local susceptibility. Based on QSM results in patients, as well as on iron staining of post-mortem SLE brain tissue, our results suggest that neuroinflammation in NPSLE is not necessarily associated with iron accumulation, and that the inflammatory pathomechanism in SLE may differ from the one observed in neurodegenerative diseases and in multiple sclerosis. |
| 4000 | Scan Efficiency Optimisation for Quantitative Susceptibility Mapping of White Matter at 7T. | |
| Jan Sedlacik1,2, Raphael Tomi-Tricot1,3, Pip Bridgen1,2, Tom Wilkinson1,2, Sharon Giles1,2, Karin Shmueli4, Jo V Hajnal1,2, and Shaihan J Malik1,2 | ||
1Centre for the Developing Brain, School of Biomedical Engineering & Imaging Sciences, King’s College London, London, United Kingdom, 2Biomedical Engineering Department, School of Biomedical Engineering & Imaging Sciences, King’s College London, London, United Kingdom, 3MR Research Collaborations, Siemens Healthcare Limited, Frimley, United Kingdom, 4MRI Group, Department of Medical Physics and Biomedical Engineering, University College London, London, United Kingdom |
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Quantitative Susceptibility Mapping (QSM) used for microstructural assessment of white matter (WM) is very attractive at ultra high magnetic field strengths, due to the increased signal-to-noise ratio (SNR) and phase sensitivity. This allows shortening echo and repetition times and, therefore, acquisition time. Further advantages of QSM are the low flip angles used for scanning, which results in low specific absorption rates, and the B1 insensitivity of the signal phase. However, suboptimal choice of imaging parameters will result in suboptimal SNR. The purpose of this work is to find and test optimal scanning parameters for QSM of the WM at 7T. |
| 4001 | Whole brain CSF segmentation for consistent zero-referencing and longitudinal study applicability of MEDI+0 | |
| Alexey Dimov1, Thanh Nguyen1, Susan Gauthier2, and Yi Wang3 | ||
1Radiology, Weill Cornell Medicine, New York, NY, United States, 2Neurology, Weill Cornell Medicine, New York, NY, United States, 3Weill Cornell Medicine, New York, NY, United States |
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The role of CSF segmentation for zero-referenced MEDI+0 is demonstrated. In the present study we show that it is essential to enforce consistency in the CSF mask between different timepoints to ensure value reproducibility and to minimize effects of random shifts in the solution of MEDI+0 minimization |
| 4002 | Artifact Evaluation of Quantitative Susceptibility Mapping Reconstructions Using Mask Parameter Perturbation | |
| Priya S Balasubramanian1,2, Alexandra Grace Roberts1,2, Pascal Spincemaille2, Thanh Nguyen 2, and Yi Wang1,2 | ||
1Cornell University, New York City, NY, United States, 2Weill Cornell Medical College, New York City, NY, United States |
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QSM uses a mask to separate tissue of interest from background to avoid the strong susceptibility sources and poor signals that are known to cause artifacts in QSM. In brain QSM, the strongly paramagnetic superior sagittal sinus (SSS) lies at the border of brain mask. Perturbing the brain mask by reducing the SSS inclusion in QSM reconstruction also affects the convergence of strong susceptibility sources inside the brain. This mask perturbation propagates into QSM perturbation, which may be used as a measure of artifacts associated with strong susceptibility sources as validated in numerical phantom and COSMOS data. |
| 4003 | Regional Susceptibility Reconstruction Improves Artifact Incidence and Error in Quantitative Susceptibility Mapping through POSSUM | |
| Priya S Balasubramanian1,2, Pascal Spincemaille2, Thanh Nguyen2, and Yi Wang1,2 | ||
1Cornell University, New York City, NY, United States, 2Weill Cornell Medical College, New York City, NY, United States |
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Quantitative susceptibility mapping methods that selectively mask based on susceptibility thresholds and do regional reconstructions have been introduced to reduce shadowing artifacts when dealing with a large dynamic susceptibility range within the image. Here, we combine this technique with total field reconstructions, which have been shown to reduce errors resulting from incomplete background field removal. Reduced errors and shadow artifacts are demonstrated when compared to prior techniques. |
| 4004 | Quantitative Susceptibility Mapping in Preoperative Assessment of Microvascular Invasion of Hepatocellular Carcinoma: a Preliminary Study | |
| Chang Liu1, Hongru Jia1, Weiqiang Dou2, Jing Ye1, and Xianfu Luo1 | ||
1Northern Jiangsu People’s Hospital, Yang zhou, China, 2GE Healthcare,MR Research China, Bei jing, China |
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In this study, we aimed to investigate susceptibility changes related to microvascular invasion (MVI) of hepatocellular carcinoma. We applied liver quantitative susceptibility mapping to measure lesions’ susceptibility. Significant differences in both tumorous and peritumoral susceptibility values were observed for MVI positive and negative lesions. With these findings, QSM imaging can be considered a potential technique for noninvasive preoperational assessment of MVI in hepatocellular carcinoma. |