[Mristudio-users] Flipping eigen vectors in fiber tracking

[Graeme Schwindt]

Hello,

>From the informative workshop here in Toronto, I have notes that indicate
when performing fiber tracking, Siemens and GE data should have the eigen
vector flipped in the X direction, and Philips in the Z direction. I have
some GE dicom data, and have followed the protocol as in the workshop,
loading in the AIRed FA map and eigenvector0 .vec file for fiber tracking.

When I chose flip in the X direction, the results of tracking appeared
wrong, with corpus callosum fibers projecting in clearly the wrong direction
and projecting for very short distances. I then tried flipping in the other
two directions, and found extremely good results when flipping in the Z
direction, which I was happy with. But I want to make sure that these
results are not spurious, though the fibers follow anatomical pathways
properly and so seem to be real. I wondered if there may be some orientation
label problem? Is it also correct to load in the eigenvector 0 as the
principal vector? Has anyone else had experience with GE dicom data and used
Z flipping?

Thanks,
Graeme

-- 
Graeme C. Schwindt, HBSc
MD/PhD Student
University of Toronto
graeme.schwindt at gmail.com
416.546.5453
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