Hi Stefan
If the transformation is just a rotation, then the tensor that you
will estimate is just a rotated tensor w.r.t. the true one.
Which means it has the same eigenvalues, but rotated eigenvectors,
i.e. the same FA.
Cheers,
Saad.
On 3 Dec 2009, at 10:50, Stefan Kreisel wrote:
> Getting the correct gradient tables (bvecs) out of your DICOM images
> has
> always been a hassle. dcm2nii does a brilliant job - unfortunately
> if your
> DICOM tags are muddled, things don't work.
> -> A simple question for you mathematicians out there: using dtifit
> requires
> the bvecs, but do I really need normalized, patient postition, oblique
> gradient etc. adjusted values? Or could I not just use the
> "standard" table
> for 6, 12 or how many directions you may have for calculating just!
> the FA.
> You clearly need the real thing for tractography, but for FA?
> Regards
> Stefan
>
--
Saad Jbabdi
University of Oxford, FMRIB Centre
JR Hospital, Headington, OX3 9DU, UK
+44 (0) 1865 222466 (fax 717)
www.fmrib.ox.ac.uk/~saad
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