Differential diagnosis between brain tumor recurrence and radionecrosis is still problematic. MR Spectroscopy Imaging (MRSI) is useful in differentiating between these two histologically and radiologically distinct entities. Six methods with different combination of metabolic parameters were used to compare 37 lesions examined by 2D/3D MRSI. The lesional and contralateral comparison of choline-containing compounds and lactate using long echo time achieved the highest sensitivity and specificity. Choline to creatine ratio showed low specificity. The distinction of regressive recurrence as a separate entity is helpful in the effort to discern the complexity of events leading to new enhancing lesions in neurooncologic patients.

DNP highly improves the sensitivity of magnetic resonance spectroscopy allowing for greater insight into in vivo metabolic activity. We used our dissolution ¹³C DNP system to monitor the Warburg effect in MIA PaCa human pancreatic carcinoma model mice subjected to radiotherapy or chemotherapy. In vivo production of ¹³C lactate in tumors showed a significant reduction after radiation therapy. Mice subjected to anticancer drugs also showed a significant reduction in the relative production of ¹³C lactate at an early stage of the treatment course before any anatomical changes in the structure or size of the tumors were detectable by MRI images.

Hepatitis B virus (HBV)-related decompensated cirrhosis is well-known risk factor for developing hepatocellular carcinoma (HCC). Therefore, it is critical to assess the risk of developing HCC in these patients. Magnetic resonance elastography (MRE) has promise in predicting future events in many chronic liver diseases, but its prognostic role in predicting HCC development of HBV-related decompensated cirrhosis remains unclear. In our study, we evaluated the performance of baseline liver stiffness measurement (LSM) by MRE in predicting HCC development in patients with HBV-related decompensated cirrhosis. Our results showed that MRE-based LSM was associated with HCC development and is independently predictive of HCC development in patients with HBV-related decompensated cirrhosis.

Evaluating short and long-term apparent diffusion coefficient (ADC) and relative fat fraction (rF%) changes could provide a better understanding of therapy response of bone metastases from breast cancer. Baseline ADC and rF% values computed from whole-body MRI, were compared with those measured at 12 and 36 week evaluations after treatment start. ADC and rF% significantly increased in responders at 12-weeks. At 36-weeks, ADC values range broadened, while rF% further increased. Short-term ADC and rF% changes are consistent with previous reports. Long-term changes highlight two patterns of response in which either high diffusion or fat repopulation prevail.

Injuries to the developing brain due to hypoxia–ischemia (HI) are common causes of neurological disabilities in preterm babies Lactoferrin (Lf) is an iron-binding protein shown to have antioxidant, anti-inflammatory and anti-apoptotic properties when administered to mothers as a dietary supplement during pregnancy and/or lactation in preclinical studies of developmental brain injuries. Here, we tested three different doses of dietary maternal Lf supplementation using the postnatal day 3 HI model and evaluated the acute neurochemical damage profile using ¹H MRS and DTI/NODDI. In conclusion, Lf supplementation attenuates, in a dose-dependent manner, the acute and long-term cerebral injury caused by HI.

Brain injuries and subsequent neurodevelopmental impairments observed following Fetal Growth Restriction (FGR) were shown to be associated with an exacerbated neonatal neuro-inflammation. The aim of this work was to characterize a rat model of FGR by advanced diffusion MRI (DTI and NODDI) and functional ultrasounds (fUS). We show in this study that neonatal inflammation lead to transient microstructural damages and subsequent behavioral and functional disabilities at long term. This model mimics very closely clinical reality in babies born following FGR. Innovative neuroimaging tools associated with this neuro-inflammatory model pave the way for their translational use in human neonates.

Cerebrovascular reactivity (CVR) is typically measured with hypercapnic challenges, which require considerable subject cooperation. Recent CVR mapping approaches using resting-state BOLD data are promising, but their sensitivity is low in subjects with minimal spontaneous changes in breathing pattern. Performed in conjunction with resting-state BOLD scans, intermittent breath modulation enhances variations in breathing pattern while requiring minimal subject compliance, and is a promising tool for CVR mapping without gas inhalation. Here we conducted simultaneous fMRI-EEG experiments to investigate origins of the global BOLD signal fluctuations during intermittent breath modulation, to verify the validity of this new approach. 

Reliable differentiation of tumor recurrence and treatment effects in glioblastoma patients is still a prevailing challenge. The purpose of this study is to identify the optimal threshold for generating fractional tumor burden (FTB) maps derived from single-dose, dual-echo based standardized relative cerebral blood volume measurements. To establish the threshold, dual-echo data was compared to the well-validated, double-dose single echo standardized FTB map. In summary, with the optimized threshold, the single-dose, dual-echo approach yielded FTB maps that strongly agreed with the reference standard, providing a compelling option for clinical use.

In this study, we evaluate the test-retest repeatability of the recently developed multi-compartment relaxometry method for myelin water imaging (MCR-MWI). Cross-protocol repeatability is also studied using 3 GRE protocols with different echo spacing and TR. Good cross-session and cross-protocol repeatability is observed for MCR-MWI. Additionally, tissue parameters along 8 major white matter bundles are studied, and myelin water fraction is the most robust tissue parameter across various protocol settings.

Microscopy data can provide detailed descriptions of how cortical microstructure varies across the brain. However, the relationship between cortical microstructure and MRI signals remains relatively unexplored. Here we develop a pipeline to extract cortical profiles from co-registered MRI and microscopy data in the BigMac dataset. We compare cortical profiles of cell density and microstructural dispersion from Nissl-stained histology slides with matched profiles from structural and diffusion MRI. Using CCA we find modes of microstructure variation common to microscopy and structural MRI, but not diffusion, indicating variable sensitivity of the MR metrics to brain-wide variations in Nissl-stained cytoarchitecture.

Sensory substitution devices (SSDs) can represent the structure of visual space through sound. To determine whether this representation is topographically organized in the congenitally blind brain, we used NORDIC de-noising and population receptive field mapping (pRF) to correlate functional brain changes to changes in sound stimulus verticality (frequency) and laterality (panning/timing) following SSD principles. We show that NORDIC significantly increased temporal signal-to-noise ratios and activation areas in subjects’ auditory cortices. PRF revealed that auditory topographic maps representing verticality and laterality emerged in occipital-parietal cortices of 3/7 congenitally blind subjects only after 10-minutes of SSD training, indicating rapid cross-modal cortical recruitment.

Blood volume fraction maps derived from diffusion weighted imaging using intravoxel incoherent motion (IVIM) modeling may be an alternative to contrast-enhanced imaging for visualization of local uterine fibroid perfusion, during magnetic resonance-guided high intensity focused ultrasound (MR-HIFU) ablation procedures. In this study, blood volume fraction maps calculated with a T2-corrected IVIM model were compared to T2-uncorrected parameter maps using two fitting techniques. Based on general inspection, T2-corrected parameter maps from deep learning-based fitting were visually the most appealing. A preliminary evaluation showed a linear association between NPVs delineated on blood volume fraction maps and gadolinium contrast-enhanced T1w scans.

MR lymphangiography (MRL) utilizing the clinically available small molecular weight gadolinium contrast agents suffers from diffusion of contrast out of the lymphatic system and into the blood pool. We describe a modified MRL technique where a clinically available iron oxide nanoparticle (ferumoxytol) is used as the lymphatic contrast agent. The higher molecular weight of these nanoparticles results in retention of contrast within the lymphatic system. This simplifies peripheral lymphatic imaging by eliminating the need for vascular contamination suppression techniques and should allow better tracking of contrast through the central lymphatics following pedal injections.

Using a 3T ioMRI system with an 8-channel intraoperative coil, we developed passive sensorimotor intraoperative fMRI protocol under anaesthesia at our site. We successfully applied it to passive fMRI of hand and foot in an exploratory cohort of four patients, confirming correspondence of activation to preoperative fMRI scans. This is the first reported implementation of intraoperative 3T passive fMRI.

MRI/CT fusion may enable MRI-guided biopsy without the requirement for dedicated interventional MRI facilities.  Assessment and training in MRI/CT-fusion biopsy requires phantoms containing targets that can be seen on MRI but not on CT and can be biopsied. These requirements are not met using commercially available phantoms. We produced a phantom containing targets that can be appreciated on MRI but not CT, which is reproducible, can be biopsied and assessed for core adequacy. We successfully biopsied targets (1-3cm diameter) using a commercially available interventional robot equipped with work-in-progress MRI/CT-fusion software, including targets with steep out-of-plane angulations, within clinically reasonable timeframes. 

Tissue biomechanical properties are highly promising biomarkers for HIFU ablation monitoring. A quantitative, MR-acoustic radiation force imaging (ARFI)-based method is proposed for measuring both tissue elasticity and viscosity, together with PRFS-derived temperature. This method is based on the identification of the MR-ARFI focal spot pattern. The method was first validated in a phantom with known properties.  The method was then evaluated during HIFU heating in a gelatin phantom. Both elastic modulus and viscosity were found to decrease as temperature increased. These results highlight the ability of this method to provide new, quantitative biomarkers of tissue thermal damage in real time.

Temperature monitoring plays an essential role in transcranial MR-guided focused ultrasound (tcMRgFUS) surgery for measuring thermal dose at the target. Unintended heating of the skull and nearby brain tissue is not currently monitored. By using a two-echo 3D spiral ultra-short echo time (UTE) sequence, we demonstrate a method that combines T1-mapping and proton resonance frequency (PRF) shift thermometry to simultaneously monitor skull and brain heating and validate it in an in vitro model.

Acute kidney injury (AKI) is associated with increased mortality in COVID-19 patients. Multiparametric MRI was performed to study renal perfusion, oxygenation and tissue structure in nineteen COVID-19 intensive care patients. Results are compared between patients with and without COVID-19 associated AKI, and with healthy volunteers (HV). Cortical perfusion was lower in COVID-19 compared to HVs (P=0.0002) with cortex and medullary perfusion lower in AKI compared to non-AKI (P<0.03). Correlations between cortex measures in COVID-19 showed T₁ was positively correlated with T₂ and ADC, and T₂ was positively correlated with ADC and T₂* suggesting interstitial oedema resulting from inflammation.

-       The proposed method allows a comprehensive relaxation times estimation (T1, T2, T2*) on MRgRT systems.

-       The methodology was validated on phantom and volunteer for accuracy and reproducibility.

-       For T1 and T2, less than 5 % coefficient of variation was observed and less than 10 % for the T2*.

-       Trends on 5 patients show a slight decrease and a recovery for the T1 and T2 values in both the boost and whole prostate during their treatment.

-       The dispersion of T1 and T2 decreased for all patients for the whole prostate whereas it was stable for the boost.

Developing preclinical imaging techniques in the field of preeclampsia is essential to test the effectiveness of new therapeutic approaches. We applied T2* weighted and three-dimensional dynamic contrast-enhanced MRI in a pregnant rat model of reduced uterine perfusion pressure (RUPP) to test their feasibility and ability to detect differences in placental oxygenation and perfusion in RUPP rats compared to control. These techniques produced high-quality data that enabled the assessment of oxygenation and perfusion parameters. Oxygenation was decreased in RUPP placenta; however, perfusion parameters did not reveal differences, which requires further investigations.

Therapeutic hypothermia can improve neurological recovery and reduce mortality in acute stroke. Pharmacologically-induced hypothermia (PIH) has been investigated in preclinical and clinical studies. Usually the core temperature (rectal or esophageal) is measured to monitor the temperature changes of the subject during the treatment. However, it remains unknown how the brain temperature is affected by PIH as the brain temperature can be different from the core temperature and affected by the anesthesia. In the present study, the brain temperature changes of adult rhesus monkeys maintained under isoflurane for over 3 hours were examined and evaluated using diffusion MRI. 

Deuterium Metabolic Imaging (DMI) is a novel method to assess metabolism in vivo using ²H MR Spectroscopic Imaging (MRSI) combined with the administration of deuterated substrates. In this pilot study, we applied 2D DMI following an intravenous injection of deuterated glucose and palmitic acid to evaluate the differences in liver metabolism of rats on standard and high fat diet at 9.4T. The spectra show a lower uptake of glucose and a higher uptake of palmitic acid after injection in high fat diet rats, indicating that liver metabolism is slowed down in rats with fatty livers.

In this study choroid plexus tissue perfusion and blood to CSF barrier function in rats were studied using long and short TE continuous arterial spin labeling technique. Non-mono exponential perfusion weighted signal decay in the CP was modelled by a two-compartment perfusion model and we report that partial volume effect is significant and must be considered to derive accurate choroid plexus tissue perfusion measurements.

· Evoked BOLD and calcium signals were recorded in the visual pathway using standard (TR=1s) and ultrafast (TR=0.3s) EPI of two TEs.

· Hemodynamic response function was estimated based on neuronal calcium activity. HRF estimated from ultrafast fMRI shows faster kinetics in the lateral geniculate nucleus than the visual cortex.

· BOLD signal was predicted from calcium signal convoluted by HRF. Using ultrafast fMRI significantly improved the accuracy of the predicted BOLD.

Non-invasive quantitative imaging of cerebral metabolic rate of oxygen (CMRO₂) is essential to understand oxidative metabolism in health and disease. Hypercapnia is often used as a calibration for MRI methods associated with quantifying CMRO₂. Here we show that CMRO­₂ remains constant during hypercapnia. We also provide a novel multimodal NIRS-MRI system that can assess absolute values of multiple metabolic correlates noninvasively in living mouse brain, and with no need for calibration with gas mixtures.  Moreover, this technique is capable to monitor mitochondrial status by measuring the redox state of cytochrome oxidase, the enzyme responsible for oxygen consumption in the cell.

Here we propose to use ¹³C diffusion-weighted MRS of hyperpolarized pyruvate and lactate to probe diffusion properties in distinct compartments of the mouse brain, tentatively extracellular (ECS) and intracellular spaces (ICS). Hyperpolarized ¹³C-pyruvate is injected intravenously and taken up by the brain before entering cells, where it is quickly converted to lactate, so that ¹³C-pyruvate concentration in ICS must remain low, while newly produced ¹³C-lactate should remain predominantly intracellular during the relatively short measurement time. We measure faster diffusion for pyruvate even after removing IVIM effect, suggesting faster diffusion in the ECS, and slow release of lactate in the ECS.

Contrast agents play a significant role in clinical MRI and are administered to detect pathology in over a third of clinical scans. Gadolinium (Gd)-based contrast agents (GBCAs) are the mainstream MRI contrast agents used in the clinic. Although GBCAs have shown efficacy and are safe to use with most patients, some GBCAs have a small risk of adverse effects, such as nephrogenic systemic fibrosis (NSF) and gadolinium deposition in the human brain. Therefore, developing novel Gd-free MRI contrast agents are in great demand. Herein, we developed a new type of MRI contrast agent using naturally derived hemin to shorten the T1 relaxation time of water.

The way brain injury can evolve has different manifestations on imaging in multiple MRI modalities, pointing to different pathological etiologies. The true picture can be seen only by correcting for free water, as it biases all the diffusion measurements, especially the longitudinal outcome. While this has been observed in humans, it is for the first time free water analysis has been carried out in a gyrencephalic pig model of TBI. In the future, co-registration with histopathological outcomes will be undertaken to verify the specificity of the diffusion measurements, which will lay the foundation for interpretation of unbiased diffusion measurements.

IDH-wildtype glioblastoma and IDH-mutant astrocytoma are classified as different gliomas according to WHO 2021. IDH mutations are key at clinical level, since they are associated with patient prognosis and seem to be critical for treatment selection. Despite these evidences, current protocols do not include the full sequencing for all tumors. In this sense, non-invasive and automatically calculated MRI-based biomarkers can be helpful for the clinical practice. 

Our results show that perfusion markers obtained in an automated, repeatable, and non-invasive manner may be candidates for being surrogate predictive markers of IDH mutation status in astrocytomas grade 4.

Although 3D T2W imaging can make up for deficiencies, such as thick layer thickness, low spatial resolution and no retrospective post-processing, of 2D acquisitions, the long imaging time and uncertain diagnostic benefits have limited its clinical application. We compared the quality of 2D, 3D and CS sense accelerated 3D T2W imaging in patients with rectal cancer and found that 3D T2W imaging resembled CS sense accelerated 3D T2W imaging, both superior to 2D acquisitions, while the latter scanning faster than the former. It’s conclude that CS sense accelerated 3D T2W imaging can substitute the 2D acquisitions.

Human renal cell carcinomas (RCC) have a variety of pathologies and are known to have alterations in cellular metabolism, although many aspects remain unknown. Fumarate hydratase (FH)-deficient tumors exhibit a shift to aerobic glycolytic system due to several factors including loss and mutation of mitochondrial DNA. We investigated the partial pressure of oxygen, vascular permeability, and blood perfusion in FH-deficient UOK262 xenografts and a type 1 papillary RCC xenograft using EPRI and DCE-MRI. Despite low oxygen consumption rates in vitro, UOK262 xenografts showed a modest median pO₂ and increased hypoxic fraction as compared to a type 1 papillary RCC xenografts.

A short quality control acquisition was developed to detect hardware issues and receiver coil positioning errors in whole-body MRI (WB-MRI). Individual coil element images were reconstructed to investigate potential broken elements and coil positioning was assessed by comparison with images acquired using the integral body coil.

This approach was implemented in a group of healthy volunteers and patients with myeloma and successfully identified a previously undetected broken coil element. The expected signal difference between coil array and integral body coil images was defined and deviation from this expected profile was used to distinguish images acquired with deliberately imperfect coil set-ups.

Neoadjuvant chemotherapy can improve oncologic outcomes and overall survival rate. However, not all patients respond well during treatment, and continuous treatment will be painful, costly, and even increase risk of progression. Thus, early stratification of treatment response and screening of patients who may not be effective in treatment is very important. We investigated the value of T1 and T2 mapping MRI in response evaluation and found that T2 value showed a significant difference between groups of pre and 1-week post-treatment, while the T1 value had no statistical difference. T2 mapping may be a useful functional biomarker for early responses evaluation.