I’m in the process of evaluating a diffusion protocol. The purpose is to do tractography of some main fiber tracts (CST, SLF, Cingulum, IFOF) and to quantify the DTI parameters in them. There is time for 60 DWIs (and some b-zeroes) and voxel size is 2 x 2 x 2.6 mm (this was the most isotropic that could be reached). I’m now wondering what the optimal configuration would be for the DWIs:
- 20 unique gradient directions repeated 3 times.
- 30 unique gradient directions repeated 2 times
- 60 unique gradient directions (not repeated)
What would you recommend, taking into account that more repetitions will result in higher SNR, but more unique directions will facilitate tractography? We tested the first version (3 x 20 unique directions) and the tracts already looked good using iFOD2 as tractography method. But perhaps there are reasons to push for one of the other options?