Do you categorize scans normalized by the scanner as derivative scans in BIDS?

Our scanner can save both original and normalized versions of a scan. Do you consider the normalized version a ‘derivative’ for the purposes of BIDS? The BIDS spec certainly suggests that should be the case (Common data types and metadata - Brain Imaging Data Structure v1.8.0), but I’m curious to know how others have handled this.

Hi @maramather,

Normalized versions of scans (and other off-the-scanner reconstructions) would probably be better going in your BIDS root directory with the rec-norm label (or something similar).


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I can see that this makes sense. However, the spec for the desc entity says:

Examples of preprocessing:

Motion-corrected, temporally denoised, and transformed to MNI space BOLD series
Inhomogeneity corrected and skull stripped T1w files
Motion-corrected DWI files
Time-domain filtered EEG data
MaxFilter (for example, SSS) cleaned MEG data

So inhomogeneity corrected is listed here which is confusing if we should instead be labeling these files using the rec-norm label. Is the critical distinction that it is an off-the-scanner reconstruction?

From BIDS website:

Even though motion correction is considered preprocessing step, the MoCo files taken from the scanner would still be labeled with rec. So you can take the same approach with norm.



Pretty much agree with all @Steven said.

That is pretty much a good rule of thumb to decide whether something is “raw” BIDS and uses the rec entity or if something is a derivative and you should consider user the desc entity.