Is it mandatory to do distortion correction in fMRI preprocessing?

Hi everyone,

I was wondering if it is necessary/mandatory to do distortion correction as a step in fMRI preprocessing? I got confused because I’ve seen papers both with and without this step in the preprocessing pipeline. (I am processing images acquired from a 7T scanner if that is relevant.)
In addition, after looking into the guides I found that I might be missing the field map / reverse phase encoding image that is needed for SDC, so I was also wondering if there is any remedy to this if the step is necessary.

Thank you very much for your help in advance!


It’s not mandatory, but it improves the alignment of your BOLD image with your T1. If you do not have a fieldmap, you can try using the SYN fieldmapless approach in fMRIPrep.


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I see. Thank you very much!