[Freesurfer] Clarification regarding bvec processing in TRACULA

Hi,

After much searching, it appears to be pretty uniform that the product DTI sequence performed on GE requires the y gradient to be flipped. For the datasets with which I am working diffusion toolkit, vistalab and exploredti all require the y gradient to be flipped. However, Tracula makes appropriate outputs when I give it the default gradient table without flipping Y. When I flip Y and run it through Tracula, the forceps major is inverted (noted by checking the overlay of dtifit_fa and dtifit_V1 using fslview and by using TVglyphView using DTI-TK.

I suspect that somehow Tracula is flipping the Y sign for the gradient (while the other programs I mentioned do not) - can anyone confirm this?

Thanks!

-Sal