Questions about illustration of sampling scheme in qsiprep HTML report

Software Support
1

Summary of what happened:

I’ve been looking through the HTML reports of my qsiprep run that I performed for my entire sample. Curiously, two participants miss the “diffusion summary” completely, but as far as I could see all the other output files were generated for them and they also have all the necessarily values in in the confounds.tsv. The end of the HTML report says that qsiprep ran with no errors, so I am assuming that this is fine.

However, when going through the HTML output files I also noticed that for a few participants (those with high mean_fd the illustration of the sampling scheme also looks a bit “weird” (to my non-expert eyes: Namely, is seems that some of the points have moved across the plane anteriorly. Is that something normal? Also, related to this, I noticed that compared to the example output of qsiprep on the web site, my sampling scheme looks stretched after preprocessing (see below). Is that something to be concerned about?

Version:

qsiprep version: 1.0.1.dev0+gee9aa2e.d20250115

Environment (Docker, Singularity / Apptainer, custom installation):

Singularity image

Relevant log outputs (up to 20 lines):

End of HTML report file (in all cases, even those two missing the diffusion summary):

Errors

No errors to report!

Screenshots / relevant information:

example_desc-samplingscheme_dwi

2

Hi @t_p,

Perhaps subjects with high motion had to have more rotation applied during Eddy to correct for motion. The different gradient in the high motion subjects might reflect the more severe b-table correction corresponding to the more motion correction?

Best,
Steven

1 Like
3

I see. The gradient (left-right difference in the GIF) actually looks like this after preprocessing in all subjects (as far as I could determine). It looks different in the example given in the qsiprep docs which is why I was wondering if this is a reason for concern or can be disregarded at this point?

Also, if the diffusion summary is missing in two participants (actually two that do not have high mean_fd) but the files seem to be there, then I guess this is a bug/quirk in qsiprep and can be ignored?