Hi @Chris_Rorden and others,
I converted a DICOM “3D_B0_map” file from a GE 3T Signa Premier scanner using MRIcroGL (1.2.20220720 x86-64 FPC) to NIfTI files. I clicked “import” and then “DICOM to NIFTI”, then I used default options, including the flag “advanced precise Philips Scaling”. There are two output files: one named “map.nii.gz” and the other “fieldmaphz.nii.gz”. However, the accompanying JSON files do not specify which file is the magnitude image and which is the field map. Based on the file names and data characteristics in the header of the files, I believe fieldmaphz.nii.gz (data ranging from -220 to 220) is the phase map and map.nii.gz (data ranging from 0.0 to 6341.0) is the magnitude map.
Could you confirm if this assumption is correct, or guide me on how to distinguish between them when the JSON files are ambiguous?
I’ve changed the file names to “sub-2mid_fieldmap”, and “sub-2mid_magnitude”.
Additionally, I need to add a “B0FieldIdentifier” key to the JSON files to comply with BIDS standards. Which of the two json files “sub-2mid_fieldmap.json”, and “sub-2mid_magnitude.json” I should add “B0FieldIdentifier”? Thanks for your help.