MRtrix3 is a neuroimaging program that can be used to performed diffusion MRI analyses. Official mrtrix3 documentation can be found here. It is advised you follow the official documentation and pipelines as it is updated frequently by the developers. MRtrix3 also has a community forum in which you can find solutions to common problems, or where you can ask your own questions.
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For official pipelines, refer to the tutorials and workflows on the mrtrix3 docs e.g:
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