What is is_derived in heudiconv outputs meaning?


In is_derived column of dicominfo.tsv file what is TRUE or FALSE meaning? Each row it is either TRUE or FALSE. Is this scans constructed from others and shall I not include it?

Actually, it say to skip this rows -> https://github.com/nipy/heudiconv/blob/master/heudiconv/heuristics/reproin.py#L491 ?

And actually, if I include this is_derived=TRUE files then https://bids-standard.github.io/bids-validator/ I get ‘DWI scans should have a corresponding .bvec file.’ error for some files.

Thanking you,

is_derived = TRUE means that image volume is derived from one of the other image volumes. For example, a T1 weighted image that is acquired in a sagittal orientation can be reformatted at the MRI workstation computer into axial and coronal planes through post-processing before being saved as a DICOM. In this example, the re-formatted axial and coronal planes would be “derived” from the original sagittal acquisition and so would have is_derived = TRUE. While the original sagittal would be is_derived = FALSE.

You’ll notice the is_derived = FALSE (the original sequence acquisitions) are typically at the beginning of your data set and the derived reformats are typically towards the end.

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Thanking you greatly Jarod,

So is it that I should not include this derived files when running heudiconv? (Would this derived files have their own .bvec files? If not, shall I not include it.)

Sorry for my poor English, thanking you for helping.

You probably just want the original if you are running some tractography or other standard analysis. Although that may vary depending on exactly what you’re doing.
The derived data are usually some post-processed version of the original data. This could re-orienting (such axial -> coronal) or for diffusion weighted may be a color coded FA or some other metric derived from the original data.