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May 10, 2022 01:05 PM | Paul Kornman - Brown University Clinical Neuroimaging
Finding diffusion directions using Bvec and Bval Files
Hello,
I need help finding out how to find diffusion directions using Bvec and Bval files for dwi data. My first theory is to count the number of bval types (e.g., if there are 20 1000s/mm2 bvals then that would equal 20 diffusion directions). Is there a way to find out how many diffusion direction per type of bval? I know mine is a multshell acquisition based on information from Andrew Jahn's website: https://andysbrainbook.readthedocs.io/en/latest/MRtrix/MRtrix_Course/MRtrix_00_Diffusion_Overview.html#mrtrix-00-diffusion-overview.
Diffusion: For each subject, we collected 2 runs of diffusion weighted imaging per session using monopoly scheme with multiple shells of diffusion values (b = 100, 200, 250, 350, 450, 550, 650, 900, and 1000 s/mm2.
Example from Khalilian et al., (2021): For data acquisition, four shells were selected at b = 1000,3000, 5000 and 10,000 s/mm2 with 64, 64, 128, and 256 diffusion directions.
I need help finding out how to find diffusion directions using Bvec and Bval files for dwi data. My first theory is to count the number of bval types (e.g., if there are 20 1000s/mm2 bvals then that would equal 20 diffusion directions). Is there a way to find out how many diffusion direction per type of bval? I know mine is a multshell acquisition based on information from Andrew Jahn's website: https://andysbrainbook.readthedocs.io/en/latest/MRtrix/MRtrix_Course/MRtrix_00_Diffusion_Overview.html#mrtrix-00-diffusion-overview.
Diffusion: For each subject, we collected 2 runs of diffusion weighted imaging per session using monopoly scheme with multiple shells of diffusion values (b = 100, 200, 250, 350, 450, 550, 650, 900, and 1000 s/mm2.
Example from Khalilian et al., (2021): For data acquisition, four shells were selected at b = 1000,3000, 5000 and 10,000 s/mm2 with 64, 64, 128, and 256 diffusion directions.