[Mristudio-users] Flipping eigen vectors in fiber tracking

[Barbara Weiland]

Graeme -

yes - we are using a GE system and are also flipping the z direction,

Barbara

-- 
Barbara Weiland, PhD
Post Doc Fellow/MEG Physicist
Neuromagnetism Laboratory
Neurology Research
Henry Ford Health System
2799 W. Grand Blvd., CFP 79
Detroit, MI  48202-2689
313-916-1075
bjweiland at gmail.com



On 6/17/08, Graeme Schwindt <graeme.schwindt at gmail.com> wrote:
>
> 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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>
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