Dear MRtrix team,
Apologies in advance for the basic question! I’m planning to do FBA analyses on a set of multi-shell dMRI data (b = 1000, 32 directions; b = 2500, 64 directions). The data is intersected by 2 b0 and 6 b100 volumes. While preprocessing the data, Eddy threw the error “Global index not DWI”. Following reading this thread Dwipreproc - Eddy error: global index not dwi
I resolved the issue by replacing b of 100 in the gradient table with 0s (as the two images are very similar) and proceeded with bias field correction and estimation of the response function using dhollander algorithm. So far, the outputs look alright. My questions are:
Does replacing b100 with 0 in the gradient table make sense?
Can this affect the output of CSD and subsequent FBA results or cause an error?
A colleague suggested discarding the actual b0 volumes from the preprocessed data, modifying the gradient table (replacing 0s with 100 as it was in the first place), and move on with the FBA analyses. What do you think of this approach? Would greatly appreciate hearing your thoughts.
Thanks a lot for your help,