I have a parcellation mask generated from freesurfer, its resolution is 256X256X256, while my DWI data is 128X128X70, can I use the atlas directly to tck2connectome without registering the space resolation between atlas and DWI?
No, there is no need to resample / regrid / reslice the parcellation image onto the same voxel grid as the DWIs in order to run tck2connectome. This is because all of MRtrix3’s tractography code operates in scanner space, which is independent of the voxel grid on which the data of any specific image are defined.
I would however avoid use of the word “registering” in this way. Ideally image data from the two modalities should be “registered” (the process of figuring out how to make the information within two images align with one another), and one image should be “transformed” to the other (moving the image information in space), but the process of defining information from one image onto the voxel grid of another via interpolation is not necessary in this context. Unfortunately many either conceptually consider or pragmatically perform all three as a single thing, which leads to the requirement for such clarifications here since we very deliberately treat them as different things.
Starting to think we need a docs page on this…
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