I have just learned of a setting on our Siemens scanner which effectively reverses the phase encoding direction if switched on: “Invert RO/PE Polarity” (https://github.com/CMRR-C2P/MB/issues/84).
Does anyone know if this inversion would be detected by dcm2nii (and subsequently passed to heudiconv) so that the correct phase encoding direction would be written to the field map and BOLD json files for fmriprep?
This concern has been raised as we have a sequence which has been incorrectly named as “xxx_PA” (posterior-anterior), which the radiographer suggested might have the geometry as A>P but the encoding direction inverted. I’d like to be sure that should this inversion option be switched on, dcm2nii would be able to catch it and label it appropriately. Invert RO/PE is “off” for the BIDS formatted data I have available, so I haven’t got an example to check against.