Previous studies have shown that cardiac CEST technique can detect myocardial metabolic abnormalities in chronic myocardial infarction. However, this navigator-gated technique is still sensitive to B₀ field variations caused by respiratory motion within the acceptance window. 

In this work, we developed a cardiac CEST dual-echo technique which not only acquires CEST-weighted image, but also enables acquisition of B₀ map for each saturation frequency offset. The reproducibility of this technique was also assessed.

We sought to quantitatively investigate the performances on blood suppression efficiency, wall-lumen CNR and plaque burden measurements for the RECS-3D MERGE sequence in carotid vessel wall MR imaging.

Twelve patients with carotid artery stenosis were recruited in this study. Lumen SNR and wall-lumen CNR were calculated and plaque burden measurements (i.e., lumen area, wall area, mean wall thickness and maximum wall thickness) were measured.

The RECS-3D MERGE was quantitatively demonstrated to have the ability to provide the comparable blood suppression, black-blood image quality and the highly correlated morphometry with the current plaque imaging protocol. The RECS-3D MERGE could be a promising tool for plaque burden measurement in a short scan time.

Dual phase whole heart imaging allows accurate depiction of cardiac segmental anatomy for congenital heart disease. We applied image-based navigation (iNAV) to improve its clinical utility. Qualitative and quantitative image quality scoring showed that iNAV gave equivalent image quality compared to the standard respiratory navigator. However, the distal coronary arteries were better visualized and the sequence duration was shorter. Using dual-phase iNAV, complete segmental anatomy was delineated in 27/30 patients (90%). The use of iNAV dual phase 3D SSFP whole heart acquisition allows complete morphological diagnosis for congenital heart disease with high image quality with more clinically acceptable time constraints.

We present the combination of ECG-triggered retrospective gating and compressed sensing for segmented 2D Cine imaging at high spatiotemporal resolution. This enables capturing the complete cardiac cycle in segmented acquisitions, while significantly reducing the total acquisition time with compressed sensing and auto-calibration. The method was evaluated in 8 healthy volunteers and ventricular function parameters were compared to reference 2D Cine acquisitions featuring ECG-triggered retro-gating. Both methods resulted in comparable image quality and equivalent quantitative values for ventricular function parameters.

Intravoxel incoherent motion diffusion weighted imaging (IVIM-DWI) is a novel functional MRI technique which has been demonstrated with excellent diagnostic capability. Respiratory motion artifacts are the main source of error in the acquisition and quantification of parameters for multi-b-value DWI. This work develops a reliable approach to compensate for misalignments between multi-b-value images during free-breathing based on pyramidal Lucas-Kanade registration. Preliminary results show that our proposed approach can well correct motion-related artifacts misalignment. In addition, visual quality of the ADC, f, D and D* maps indicate that contours of kidney look better defined after registration.  

The purpose of this study was to propose a robust technique for the determination of unbiased kurtosis values in body applications; for this aim, a new strategy to pixelwise estimate the noise level in DKI acquisitions is described and its feasibility for pelvic DKI is demonstrated in prostate tissue.

The "naive" evaluation (without considering the image noise) resulted in significantly biased positive kurtosis values of urine of $$$K=0.42\,($$$standard deviation: $$$0.06)$$$, indicating non-monoexponential signal decay caused by the influence of noise at higher b-values. This bias is almost completely removed ($$$K=-0.01\,(0.32)$$$) after including the pre-calculated noise-level map in the evaluation.

Hepatobiliary phase image on gadoxetic acid-enhanced magnetic resonance (MR) imaging has been described as a way to quantify liver function and potential to estimate regional liver function.  The purpose of this study was to investigate whether gadoxetic acid-enhanced MR imaging can estimate lobar liver function by comparing with ^99mTc-GSA SPECT imaging.

The results of this study showed that hepatic lobar function significantly differs according to the presence of biliary obstruction.  Combined volumetric and functional assessment calculated by hepatobiliary phase images on gadoxetic acid-enhanced MR images can estimate lobar liver function.

Acquiring high spatial-temporal resolution images is important for dynamic contrast-enhanced (DCE) imaging. In this work, we proposed a weighted k-t SPIRiT method and tested it in both simulation and in-vivo liver imaging studies based on motion-insensitive golden angle radial stack-of-stars sampling. In this study, feasibility of the weighted k-t SPIRiT has been validated. The results showed that, weighted k-t SPIRiT can improve the image quality compared with SPIRiT, while preserve highly accurate temporal information.

Scan time reduction with partial Fourier was investigated for 4D flow MRI of mean velocity and turbulent kinetic energy. It was shown analytically, that PF leads to a loss in resolution for phase images. According to experiments with in-vivo data, the precondition of slowly varying phases is not met for PF reconstructions of 4D flow MRI, making homodyne reconstruction and POCS fail. Therefore, it is concluded, that PF cannot recover missing k-space samples in 4D flow MRI and does not offer a benefit over symmetric k-space sampling with the same number of phase encodes.

Acute pulmonary hypertension was induced in dogs by micro embolization. RHC was performed, as well as 4D flow MRI pre and post-embolization. MRI data was used to develop a CFD model of the proximal pulmonary circulation while comparing two inlet boundary conditions: velocity definition as defined from 2D flow MRI and from 4D flow MRI, which takes into account the directionality of the velocity. WSS tended to decrease post-embolization. Pressure gradient distribution shows that during peak systole, a constant normal inlet condition might be sufficient for CFD simulation; however, differences might be present during diastole.

4D flow normally uses respiratory gating to mitigate breathing artifacts for thoracic and abdominal applications. Respiratory Controlled Adaptive k-space Reordering (ReCAR) employs k-space reordering based on the current respiratory position. It has been reported to increase respiratory gating efficiency for 4D flow applications. The purpose of this study was to systematically compare the image quality of 4D flow data acquired with and without adaptive k-space reordering.