I am new to dealing with distortion correction by field map. In my dataset, one field map scan (two images with different echo times) was acquired before resting-state fMRI scan. My question is that the field map could be used for DWI distortion correction as well? My guess is that the field map reflect the B0 field inhomogeneity and should not take a big change during an MRI session. I tested this idea on one subject data and it seems the DWI distortion was corrected to some degree. However, I don’t know whether this is a commonly accepted way of acquiring field maps and doing distortion correction?
Thanks, Steven. I will test these field-map-free methods on my data and make some comparisons. I prefer these methods to using a field map scan, because standardizing the processing flow is easier without a field map in my opinion.
Hi @Steven, I tested SynBOLD-DisCo on an example dataset provided by FSL, and compared the performance of distortion correction by visually checking the T1-fMRI registration accuracy. As shown in the figure below, it seems that using a real field map leads to better T1-fMRI registration than using SynBOLD-Disco. However, visual check is sort of subjective and it is possible that there is an interaction between distortion correction and registration approach. Are there any other ways to evaluate the distortion correction performance?
