BIDS Validator Errors: Code 54, Code 66, Code 75


I just validated my dataset using and have come across a few errors. Most of them are small and easily fixed, however I am not sure how to fix Error Code 54, Error Code 66 and Error Code 75.

Error Code 54: BOLD_NOT_4D, Bold scans must be 4 dimensional.
This error is only occurring consistently across participants/scans. Each participant has 2 rest and 4 task-based bold scans. However, not all participants have the same error on the same scans. For example, one participant only gets the error on 1/2 rest scans and 1/4 task-based scans. While another gets the error on 2/2 rest and 3/4 task-based.
These dicoms were converted using dcm2niix.

Error code 66: SLICETIMING_VALUES_GREATOR_THAN_REPETITION_TIME. This error suggests that SliceTiming values should be in seconds not milliseconds, and should be smaller than TR. Our TR is 1s, and the slice timing error here occurs when the SliceTiming values are above 1s. They are in seconds not milliseconds so I’m not sure how to fix this.

Error Code 75: NIFTI_PIXDIM4. Nifit file header is missing time dimension information.

Another thing I noticed is that the same files get all three of the errors. That is, if a run (e.g. rest run 1) got the BOLD NOT 4D error it also gets the SliceTiming and Nifti time dimension errors. All the files are converted at once in a script that calls dcm2niix, not sure what it is about those acquisitions that is problematic. Finally, each participant does not get the errors on the same acquisitions/ sequences. It is not consistent across participants.

Thank you, I hope this makes sense. Please let me know if I can provide any additional info/screenshots.


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A colleague helped me on this and it seems dcm2niix did not convert some of the files correctly and the dimensions were not correct. I think that may solve some of the errors, but not the SliceTiming parameter error. Any suggestions on that? The validator says it’s a common error.