fixel2sh and sh2peak issue

Dear MRTrix community,

We would like to focus the change by disease in FBA. DWI data was processed under the pipeline in MRtrix3 recommended.

The WM-FOD (sagittal view) in projection fiber near the ventricle was:

The FD result (sagittal view) in one subject in the same view was:

The fixel2sh was executed in this subject and the SH result (sagittal view) was displayed in the same view.

Finally, the sh2peaks was executed in the SH result and sh2peaks result (sagittal view) was displayed in the same view.

I don’t understand why there exist the different orientation (Can I call it that?) in final sh2peaks result compared with the WM-FOD or FD result.

Thank you for your great help!

Welcome @NAS!

The fixel2sh was executed in this subject and the SH result (sagittal view) was displayed in the same view.

The data being shown in the corresponding screenshot were produced by the fixel tool, but the output of the fixel2sh command is an SH series, which should be displayed using the ODF tool. It might be useful to be able to see those intermediate data to know where the problem first originates.

I don’t understand why there exist the different orientation (Can I call it that?) in final sh2peaks result compared with the WM-FOD or FD result.

Neither do I. These kinds of orientation flips can happen, e.g. converting between formats, but not normally in a subset of the image like that. I did a quick sanity check that that sequence of commands doesn’t cause an issue on an exemplar dataset. But I’m kind of baffled.

In addition to fixing the screenshot for the output of fixel2sh, it would be useful if you could post the exact commands that were used to generate the final result.
(If you’ve used the .mif format throughout, you could run mrinfo -property command_history on the output of sh2peaks and post the relevant content here)

Cheers
Rob