Hello Everyone,

I'm creating VDM maps for distortion correction in my preprocessing using two magnitude volumes and one phase volume.  I get this error in one participant:

ERROR DESCRIPTION:
Error using sqrtm (line 35)
Expected input to be finite.
Error in pm_segment>get_p (line 581)
Error in pm_segment>run_segment (line 364)
Error in pm_segment (line 119)
Error in pm_brain_mask (line 48)
Error in FieldMap (line 1611)
Error in FieldMap_create (line 146)
Error in conn_setup_preproc (line 2432)
Error in conn (line 1081)
Error in conn_menumanager (line 120)
CONN18.b
SPM compiled
Matlab v.2018b
project: CONN18.b
storage: 853.4Gb available
ans =
logical
1


In a couple of similar questions, I saw that one suggested solution was to add a small constant value of 1/1000 to the magnitude files.  I've checked the range of the two magnitude/echo files however and none have any zero-valued voxels, the range is between ~25 - 1500. I've already specified the input format vs letting the code determine it. Anyone have any ideas of what else to try?

I also have a mag/phase files generated in FSL with the phase diff file in rad/s, so conceivably I could create a json file that had the units set to that, but I haven't been able to find an example json file that shows the required format nor how to input such a file into the processing step.

Any advice is appreciated and thanks in advance.

regards,
Karl