Run parameter for Diffusion imaging


We’ve run into an issue with the BIDS naming schema. We have been collecting multiple runs of diffusion imaging on our subjects within a single session. According to the standard BIDs specifications, _run- is not a valid option for diffusion data. Is it possible to include _run as a valid option for diffusion data? If not, any suggestions on how to deal with multiple runs?


I just had a look at the spec and _run is definitely part of the spec for DWI data (see


What made you say run is not a valid option?

Interesting. It’s not listed in Appendix IV as a valid option, and the online BIDS validator is giving us a naming error for all our diffusion data. Our files are names:
sub-_ses-_acq-_run-_dwi.nii.gz (example: sub-STELLA_ses-20180515_acq-DSIq5_run-1_dwi.nii.gz). The BIDs Validator is passing back the error: “Files with such naming scheme are not part of BIDS specification.”

I fixed the table in the most recent draft - thanks for reporting.

I had a look at the validator code and this should work. What is the full path to the file that gives you issues?

So I’m using the online validator with some local data on our servers. The local path is /projects/bruss/tmp_data/BIDS_warehouse/sub-STELLA/ses-20180515/diff/. Every file in that directory is passing back the same naming error.

I passed the BIDS_warehouse to the online validator (

I see the problem now. Try renaming diff to dwi.

Thanks that fixed the error. We’ll replicated that change into our converter and file structure.

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