MR imaging of the female pelvis at 3 Tesla: Evaluation of image homogeneity using different dielectric pads.

PURPOSE: To evaluate improvements in image homogeneity in pelvic MR imaging at 3 Tesla (T) using two different dielectric pads. MATERIALS AND METHODS: A total of eight healthy females were scanned using a 3T MR scanner equipped with a body-array coil. Axial and sagittal fast spin-echo T2-weighted images (T2WI) (TR/TE = 3200 msec/94 msec), axial fast spin-echo T1-weighted images (T1WI) (TR/TE = 700 msec/11 msec), and sagittal half-Fourier acquisition single-shot turbo spin-echo (HASTE) images (TR/TE = 3000 msec/100 msec) were performed for pelvic imaging. Sequences were repeated with dielectric pads (consisting of either ultrasound [US] gel or water), and without pads. Three or four regions of interest (ROIs) were placed on fatty tissues and the ratio of minimum to maximum signal intensity (RSI) was calculated as a marker of image homogeneity. RESULTS: RSI was significantly higher on T2WI and T1WI when using dielectric pads than when no pad was used. A similar tendency was observed in RSI on HASTE. No significant difference was found between images with US gel pads and those with water pads. CONCLUSION: Dielectric pads consisting of either US gel or water are effective in improving image homogeneity of the pelvis on 3T MRI. (c) 2007 Wiley-Liss, Inc

MRCP imaging at 3.0 T vs. 1.5 T: Preliminary experience in healthy volunteers.

PURPOSE: To evaluate the impact of magnetic resonance cholangiopancreatography (MRCP) imaging at 1.5T and 3.0T on image quality. MATERIALS AND METHODS: Fourteen volunteers were examined at both 1.5T and 3.0T using MRCP imaging performed with a breath-held two-dimensional (2D) half-Fourier acquired single-shot turbo spin-echo (HASTE) thick-slab sequence, a free-breathing navigator-triggered three-dimensional (3D) turbo spin-echo (TSE) sequence with prospective acquisition correction, and a heavily T2-weighted (T2W) sequence with breath-held multislice HASTE. All images were scored for visualization of the biliary and pancreatic ducts, severity of artifacts, image noise, and overall image quality. RESULTS: MRCP imaging at 3.0T yielded a significant improvement in overall image quality compared to 1.5T. We found a trend for superior visualization of the biliary and pancreatic ducts at 3.0T. Heavily T2W imaging with thin sections (1.4 mm) at 3.0T provided diagnostic images and better visualization of the biliary and pancreatic ducts than heavily T2W imaging with standard sections (2.8 mm) at 3.0T. CONCLUSION: Our experience suggests that MRCP imaging at 3.0T has the potential to provide excellent images. High-resolution heavily T2W imaging with a small voxel size (1.3 x 1.3 x 1.4 mm) at 3.0T can provide diagnostic images and allow evaluation of small pathologies of the bile and pancreatic ducts, which 1.5T MRI cannot sufficiently visualize

Diffusion Tensor Imaging of Kidneys With Respiratory Triggering: Optimization of Parameters to Demonstrate Anisotropic Structures on Fraction Anisotropy Maps

PURPOSE: To demonstrate the feasibility of diffusion tensor imaging (DTI) of kidneys with respiratory triggering, and determine the optimal imaging parameters for fraction anisotropy (FA) maps. MATERIALS AND METHODS: DTI of kidneys from 16 healthy volunteers was performed using a 1.5T scanner. Five different sequences with different parameters including respiration-triggered acquisition or multiple breath-holding, slice thicknesses of 3 or 5 mm, and different numbers of signal averaging and b values were compared. FA and apparent diffusion coefficients (ADCs) of the cortex and medulla were measured. Measurement error within the same and repeated examination was examined using within-individual standard deviation (Sw). RESULTS: FAs of the renal cortex were lower than the medulla (mean value of a sequence ranging 0.148-0.224, 0.433-0.476) and the ADCs of the cortex were higher than the medulla (2.26-2.69x10(-3) mm2/s, 1.77-2.19x10(-3) mm2/s) in all sequences (P<0.001). The renal cortex-medulla difference was the largest, with respiratory trigger- ing including a 3-mm slice thickness, three signal averages,and a b-value=0, 200, or 400 s/mm2 (P<0.001). Sw tended to be smaller in the sequence with a b-value of 400 s/mm2. CONCLUSION: DTI of kidneys with respiratory triggering is feasible with excellent cortex-medulla differentiation