Greetings Dr Schwarz et al.
I just started testing mri_reface on DICOM images. I had some questions about the conversion process.
Several DICOM attributes are modified. Some are logging that deidentification was done (0012,006x). Others I'm less sure about. Leaving out the former, I saw these changes in my test image:
(0008,0013) InstanceCreationTime: deleted
(0008,0018) SOPInstanceUID: modified [redacted]
(0008,0033) ContentTime: deleted
(0019,1015) Private [Siemens MR header: SlicePosition_PCS]:
deleted
(0020,1041) SliceLocation: deleted
(0028,0101) BitsStored: modified 12 -> 16
(0028,0102) HighBit: modified 11 -> 15
(0028,0103) PixelRepresentation: modified 0 -> 1
(0028,0107) LargestImagePixelValue: modified 11 -> 10
(0028,1050) WindowCenter: deleted
(0028,1051) WindowWidth: deleted
(0029,1010) Private [Siemens CSA header: CSAImageHeaderInfo]:
deleted
(0051,100D) Private [Siemens MR header: SlicePositionText]:
deleted
(0054,0081) NumberOfSlices: added -> 176
(0054,0101) NumberOfTimeSlices: added -> 1
The SOP instance UID makes sense: it says the instance was created by pydicom.
I think the (0028,010x) tags are modified because the pixel data are converted to float when read into nibabel. The largest value could change if the slice includes a face voxel (this is slice 1, so it's probably low because it's mostly air).
The private tag (0029,1010) Siemens CSA header: CSAImageHeaderInfo is listed as preserved in the LONI deidentification protocol (not required though).
I'm considering restoring some of these in a separate postprocessing pass. Can you comment on this, particularly is replacing any tags may be invalid.
Many thanks
Paul