17283t7t磁化率加权成像回波间方差通道组合技术优化扎尼.pdfVIP

Optimization of Inter-Echo Variance Channel Combination Technique for Susceptibility Weighted Imaging at 3T and 7T 1 2 2,3 Zahra Hosseini , Junmin Liu , and Maria Dran a 1 2 Biomedical Engineering Graduate Program, Western University, London, Ontario, Canada, Imaging Research Laboratories, Robarts Research Institute, London, Ontario, Canada, 3Medical Biophysics, Western University, London, Ontario, Canada TARGET AUDIENCE: Researchers and clinicians interested in vein visualization in brain. INTRIDUCTION: Susceptibility weighted imaging (SWI) is an established MR technique for visualization of veins in the brain. Because susceptibility affects the phase of the complex MR signal, the phase images are used to generate masks that are applied to the magnitude images to rease contrast between veins and surrounding tissues. When multi-channel acquisition is used a robust channel combination technique is required to prevent phase image corruption.1 Recently, a channel combination technique, based on calculating the inter-echo variance (IEV), was introduced and shown to generate accurate local frequency (LFS) maps from multi-echo acquisitions.2 In this study, we evaluate and optimize the application of the IEV technique to SWI in the brain at 3 and 7T. METHODS: Imaging: Healthy volunteers were imaged at 7T and 3T using 16- channel and 32-channel head coils, respectively. Three-dimensional (3D) multi- echo gradient echo sequences were used (7T: 6 echoes, TR/TE/Echo spacing: 40/3.77/4.1 ms, matrix: 380 x 340 x 102; 3T: 4 echoes, TR/TE/Echo spacing: 42.5/13.0/3.8