BIDS - nonstandard ex vivo B1+ mapping

Hi BIDS experts,

We’re trying to organize our ex vivo MRI data into BIDS-compliant format, and are facing issues with our B1+ maps.

We are not using any of the standard B1+ mapping protocols listed in the qMRI appendix and are not sure how to best organize this data. To measure B1, we acquire FLASH images with many different flip angles and a long TR, and fit the bloch equation using a look-up table.

I see three potential ways of organizing this data:

  • Create a new TB1 file collection (TB1VFA?), but this does not seem to be BIDS-compatible
  • Use one of the standard TB1 suffixes. This feels very wrong.
  • Add them as anatomical VFA data. But I am worried it will confuse users, who will have to differentiate between the actual high-resolution anatomical VFAs, and the low-resolution VFAs used for B1 mapping.

Is there a good way to do this?