Nope, there's no flipping in tracula. But, *both* the gradient vectors and the DWIs are converted to LAS orientation as the first step in the preprocessing. This makes the FSL tools that are run later in the preprocessing (dtifit and bedpostx) run smoothly without any flipping.
On Mon, 26 Aug 2013, Salil Soman wrote:
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
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