2 phases SDC outputs partial fieldmap

[jhauneuro]

Summary

When I preprocess my dwi data using 2 phases for susceptibility distortion correction (SDC), the estimated fieldmap appears to be truncated (has only partial brain coverage). The original dwi and fmap data have the same field of view and fully cover the brain. I have successfully preprocessed these data in FSL separately and did not get a truncated or partial fieldmap result. Any idea what is going on or how to fix this?

Additional details

• QSIPrep version: 0.22.0
• Docker version: 25.0.4

What were you trying to do?

Preprocess dwi data using 2 phases for SDC.

What did you expect to happen?

Successfully preprocess the data.

What actually happened?

SDC produced a partial fieldmap and the data were only partially corrected for susceptibility distortions.

Reproducing the bug

Screenshots of the fieldmap:

and reference EPI image: