@Carlos_Z this is related to dcm2niix issue 455. Thank you for the PAR/REC sample. If anyone in the community has Philips DICOMs that also show pre-computed field maps, I would be grateful to see a set. I think Philips PAR/REC files are underspecified to compute FSL Fugue’s definition of dwell time, as we need to treat partial Fourier and SENSE differently. As I recall, if you provide a field map (which you have), the dwell-time only impacts the scaling for the calibration image generated by Fugue, and not the actual undistorted. Therefore, it does not impact subsequent analyses. So I think you can just put in your best guess (you can test this by computing the results for dramatically different dwell-times).