Multi-shell DTI report showing same SNR for best and worst volumes

[HQHuang]

What happened?

We ran MRIQC in docker to get a report on multi-shell diffusion data (1 scan of b=0, 64 scans of b=1500 and 64 scans of b=3000). For shell1 (b=1500), we got same snr values for best and worst volumes. However, for shell2 (b=3000), we got a high snr for best volume and low snr for worst volume. See the screenshot below.

What command did you use?

docker run -it --rm -v $mriqc_in_dir:/data:ro -v $mriqc_out_dir:/out nipreps/mriqc:latest /data /out participant --participant_label ${mriqc_group} --n_procs 6 --no-sub

What version of the software are you running?

24.1.0.dev0+g3fe90466.d20240417

How are you running this software?

Docker

Is your data BIDS valid?

Yes

Are you reusing any previously computed results?

No

Please copy and paste any relevant log output.

No response

Additional information / screenshots

No response

[oesteban]

@HQHuang could you share this particular image? If not, have you opened the file and checked whether it looks generally good (meaning, that the b-1500 is not always the same or something weird).

[oesteban]

cc/ @arokem

[HQHuang]

@oesteban Thank you for the reply! The 64 images from shell1 (b=1500) look different from each other. The whole diffusion file is too large to be uploaded here. Here I attached the screenshots of the first two volumes in shell1. Please let me know if you need further information!