Hi Matt,
I want to evaluate whether the regions seen with GM atrophy (by VBM) also show reduction in DTI metrics in my patient population. I would like to see whether DTI (to my understanding reflects microscopic changes) changes agree with GM changes (which I believe reflects macroscopic changes). In order to study this I am not sure which DTI measure to use because to my understanding FA is more appropriate to study WM instead of GM, similarly radial diffusivity as it reflects more of myelin changes whereas I can use MD and axial diffusivity (which I believe reflects more of changes in axonal membrane, microfilaments and microtubules similalrly I beleive that axial diffisivity in GM will be reflective of damages to membrane). Please correct me whereever I am wrong and suggest what will be appropriate DTI measure to use.
Thanks
Venkat
________________________________
From: FSL - FMRIB's Software Library on behalf of Matt Glasser
Sent: Fri 3/23/2012 12:30 PM
To: [log in to unmask]
Subject: Re: [FSL] Gray Matter DTI
What is your hypothesis?
Peace,
Matt.
-----Original Message-----
From: FSL - FMRIB's Software Library [mailto:[log in to unmask]] On Behalf
Of Rajagopalan, Venkateswaran
Sent: Friday, March 23, 2012 11:26 AM
To: [log in to unmask]
Subject: Re: [FSL] Gray Matter DTI
Thanks Saad, could you tell me whether axial diffusivity be an appropriate
measure to study changes in GM or what measures of DTI will be more
appropriate to study GM changes.
Thanks a lot
Venkat
________________________________
From: FSL - FMRIB's Software Library on behalf of Saad Jbabdi
Sent: Fri 3/23/2012 8:52 AM
To: [log in to unmask]
Subject: Re: [FSL] Gray Matter DTI
Hi
Dear All,
I am interested in studying DTI changes (MD, I am wondering whether
it will appropriate to study axial diffusivity also in the sense for
instance FA is more for WM than GM) in gray matter between control and our
patient population. I am wondering what is way to segment white matter (WM)
from gray matter (GM).
You can use FAST on a T1-weighted image and map back onto DTI space using
FLIRT.
I am also interested in extracting different lobes of the brain to
study GM changes in each lobe. Basically based on our VBM results where I
see GM volume changes I would like to study whether DTI measure MD changes
in frontal, temporal, occipital and parietal lobes. If so, is there a way I
can use the atlases to separate out different lobes of the brain.
You can use the MNI structural atlas in fslview.
Saad
Thanks
Venkat
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University of Oxford, FMRIB Centre
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