Bvecs retreived by transformation matrices

Hello everyone,

I am trying some FODs reconstruction and the dataset is peculiar in a way: The acquisition was not based on a coil gradient scheme, but the gradient was stable and directions changed by re-orienting the object inside the MF (with stable center), 60 times, on angles pre-set by electrostatic repulsion on sphere surface.
Each direction transformation was obtained by registration of the re-orientations to the reference and converted to a vector.
Could these vectors be directly used in -fslgrad bvecs selection or you spot any issue on the described process/difference with the regular bvecs from gradient schemes?

Thank you!

Whoa, that sounds interesting!

As long as the reorientation of the gradients is correct, I reckon that should work as expected. Personally, I’d be more worried about matching all the different geometric distortions, etc across volumes, but I assume you’ve got all that under control. I’d love to see what you’re cooking up here… :yum:

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So… the “cooking” in that case doesn’t have to do only with diffusion actually…!
The aim is to study the possibility of deriving FODs in white matter, based on high-angular local phase data (susceptibility induced phase) which regionally exhibit highly anisotropic characteristics, and subsequent comparison with the same analysis on DTI data.
The experiment acquisitions include multi-orientational DTI, STI data on post-mortem brains, and gradient scheme-based DTI acquisitions for reference. The processing is pretty long, including of course calculation of the FODs using MRTRIX.
On a first analysis (we are on the way for a new acquisition), the preliminary results look promising on the main fibers, like CST, despite I have some issues with the coloring of the FODs in mrview as the scanner vs image coordinate system seems to be confused in a non-clear way (for me).

I would be happy to share more details with you if you are interested, and of course any suggestion is more than welcome!