Hi
> Hi,
> I tried to analyze DTI got from Phillips Scanner. I have several
> questions:
> 1) dtifit step, I got some dti_FA ( dti_V1...) result. I open the
> dti_V1
> and dti_FA. They looks OK. Some color image similar to the website.
> How can
> I verify that the result is correct ( especially dti_FA ). There
> are a lot
> of e-mails mention that *-1 in bvecs. some FA values >1, how to
> adjust it?
dti_FA is unlikely to be sensitive to a sign change in your bvecs.
dti_V1 will be.
Load dti_V1 into fslview, and select "lines" mode. Make sure vectors
in the corpus callosum line
up with each other in all three views (by "line up", I mean form a
continuous path)
This will tell you about "-1" errors. It will not tell you about more
subtle errors in bvecs.
You should find out if your images were acquired in "pure axial"
sections, or if there was a rotation of the axial slice.
If there was a rotation, have the bvecs been corrected for this
rotation?
>
> 2) We use 16+1(B0) volumes. Is it OK to do fiber tracking. Because our
> subjects are dementia patients. We can't hold them too long.
Sure - You will probably be limited to tracking major fibre bundles.
> 3) Fiber tracking step. Because I'm not sure where I put ROI, how
> can I
> know the tracking is make sense. For example, typical cortical-spinal
> tracking to see the motor function of brain, I follow steps
> described in
> some papers but I can't get same fiber result.
I guess this will be because your bvecs are defined wrong (see above)
> Is there some links
> talking about basic fiber tracking use FSL.
http://www.fmrib.ox.ac.uk/connectivity/
and follow the software links there... plenty
> It's better that there is an
> example data attached.
There is example dataset in the fsl course data which you can get at
www.fmrib.ox.ac.uk/fslcourse
cheers
T
> Then I can repeat it.
> Anyone has some idea or hint? Thanks a lot!
>
> Chunchun
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