Oh Great BIDS Gurus,
I am trying to figure out whether my func metadata is supposed to have PhaseEncodingAxis or PhaseEncodingDirection as its metadata field name for our BIDS app. The standard currently says this about PhaseEncodingDirection:
RECOMMENDED. Possible values:
k-. The letters
kcorrespond to the first, second and third axis of the data in the NIFTI file. The polarity of the phase encoding is assumed to go from zero index to maximum index unless
-sign is present (then the order is reversed - starting from the highest index instead of zero).
PhaseEncodingDirectionis defined as the direction along which phase is was modulated which may result in visible distortions. Note that this is not the same as the DICOM term
InPlanePhaseEncodingDirectionwhich can have
COLvalues. This parameter is REQUIRED if corresponding fieldmap data is present or when using multiple runs with different phase encoding directions (which can be later used for field inhomogeneity correction).
So, which is it? Is PhaseEncodingAxis an artifact of an older standard version maybe?
P.S. I also found this conversation: https://github.com/rordenlab/dcm2niix/issues/258
~Eric Earl, OHSU