Naming b0maps for fMRIprep

Hello experts!

I asked same question 9 days ago, but I couldn’t progress with this problem.

I have 6 files for fieldmap, as named like below

From the fact that this data was taken from Gradient echo-EPI sequence, I guess just e1 and e2 data might be magnitude1 and magnitude2. (or is this is just complete fieldmap for preprocessing?)

and I guess that Real and imaginary files might be needed to convert into Complex file, and transform into phase file from fsl FUGUE(FUGUE/Guide - FslWiki).

So, I tried ‘slices’ for 6 files. and then

for e1






My question is,

  1. if my hypothesis is true(I should transform real + imaginery = complex → complex = phase + magnitude)
    then, why I need for e1 and e2? or I don’t need to do such a thing for progress?

  2. how to make these files work on fmriprep? If I do fsl preprocessing(fslcomplex and prelude and so on), I don’t have bids json file for derivates from fsl, so I can’t progress on fslprep

Thank you a lot!