Partial Fourier tag

[neurolabusc]

The text for 01-magnetic-resonance-imaging-data.md defines PartialFourier as The fraction of partial Fourier information collected. Corresponds to DICOM Tag 0018, 9081. Be aware that 0018,9081 is an enumerated type of YES/NO not a fraction, e.g. (0018,9081) CS [YES]. Might be worth spelling this out, e.g. scan acquired with 5/8 Partial Fourier would report 0.625. I am not aware of a public tag that reports the desired value (for Siemens one can look at the CSA header).

[agahkarakuzu]

@neurolabusc great catch! Thank you for bringing this to our attention. I also could not find any generic tag for the partial Fourier fraction, that corresponds to the current description.

I am not sure how widely this metadata is used by the existing data. Depending on the answer, backwards compatibility may prevent us from a complete redefinition. If anything, we can drop Corresponds to DICOM Tag 0018, 9081 to avoid confusion and improve the description.

[neurolabusc]

Yes, I would simply drop the reference to the DICOM Tag. At the moment, dcm2niix reliably reports the PartialFourier for Siemens (ucPhasePartialFourier in CSA header). I would be happy to hear if anyone knows how to determine this for Philips or GE.