Magnetic resonance imaging
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Diffusion weighted magnetic resonance imaging (DWI) has been mostly acquired using single-shot echo-planar imaging (ss EPI) to minimize motion induced artifacts. The spatial resolution, however, is inherently limited in ss EPI especially for abdominal imaging, even with the advances in parallel imaging. A novel method of reduced Field of View ss EPI (rFOV ss EPI) has achieved high resolution DWI in human carotid artery, spinal cord with reduced blurring and higher spatial resolution than conventional ss EPI, but it has not been used to pancreas imaging. ⋯ However, subjective scores of image quality was significantly higher at rFOV ss DWI (P=0.008 and 0.000 for b-value=0s/mm(2) and 600s/mm(2) respectively). The spatial resolution of DWI for pancreas was increased by a factor of over 2.0 (from almost 3.0mm/pixel to 1.25mm/pixel) using rFOV ss EPI technique. Reduced FOV ss EPI can provide good DW images and is promising to benefit applications for pancreatic diseases.
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Coronary artery stents are made from metallic mesh and, therefore, to ensure patient safety, these implants must be evaluated to determine risks associated with MRI. Recently, bioabsorbable scaffolds, which have metallic markers, have been developed for use in the coronary arteries. Because of the metallic materials, these implants may present issues for patients undergoing MRI. Therefore, the objective of this investigation was to assess MRI issues (i.e., magnetic field interactions, MRI-related heating, and artifacts at 3 T) for a new bioabsorbable, coronary artery scaffold with metallic markers. ⋯ The results demonstrated that the coronary artery scaffold is acceptable (or "MR conditional," using current MRI labeling terminology) for a patient undergoing an MRI procedure at 3 T or less. To our knowledge, this is the first bioabsorbable, coronary artery scaffold that has been evaluated for MRI issues.
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Diffusion-weighted magnetic resonance imaging (DWMRI) is used to study white matter (WM) in normal and clinical populations. In DWMRI studies, diffusion tensor imaging (DTI) models the WM anisotropy with one dominant direction, detecting possible pathway abnormalities only in large and highly coherent fiber tracts. However, more general anisotropy models like Q-ball imaging (QBI) may provide more sensitive WM descriptors in single patients. ⋯ Particularly, the left corticospinal tracts resulted more markedly depicted by the QBI than by the DTI model, with GFA predicting ALS disability better than FA. The present findings demonstrate that QBI model is suitable for studying WM tract degeneration in population-level clinical studies. Particularly, group-level studies of fiber integrity may benefit from QBI when DTI is biased towards low values, such as in cases of fiber degeneration, and in regions with more than one dominant fiber direction.