Hi Antonio,
that's why we we use the surfaces for white matter and cortical gray
matter volume.
cheers,
Bruce
On Mon, 25 Jun 2007, Gallo, Antonio (NIH/NINDS) [F] wrote:
Hi Bruce,
Thank you for your quick response.
Our problem, actually, is that when we visualize the aseg.mgz volume
(with color-coded subcortical structures) we see that WM is classified
as GM (left circle around insula in the figure) and GM is classified as
WM (right lower circle in the figure).
So, even if the surfaces look good, we are worried about the effects of
this misclassification on volume measurements in aseg.mgz.
Thanks,
Antonio
-----Original Message-----
From: Bruce Fischl [mailto:[EMAIL PROTECTED]
Sent: Monday, June 25, 2007 4:10 PM
To: Gallo, Antonio (NIH/NINDS) [F]
Cc: freesurfer@nmr.mgh.harvard.edu
Subject: Re: [Freesurfer] Segmentation
Hi Antonio,
I wouldn't use the wm.mgz for much of anything. It's really just an
intermediate step in the creation of the surfaces. In general we trust
the
?h.white and ?h.pial surfaces first, then the aseg.mgz for things like
hippocampus, ventricles, etc...
Bruce
On Mon, 25 Jun 2007, Gallo, Antonio (NIH/NINDS) [F] wrote:
Hi All,
Upon reviewing subortical segmentations I see that often a mismatch
exists between what appears on the wm.mgz and the color-coded
segmented
maps.
Precisely - as an example - in the attached figure you can see that
in
the case of left insula WM, part of the tissue was classified as GM
(in
brown) in the color-coded segmented map and as WM in the wm.mgz.
Contrariwise, the right temporal-parietal GM cortex part of the
tissue
is classified as WM (in green) the color-coded segmented map and as
non-WM in the wm.mgz. The latter occurs in many regions of the brain
without a clear anatomical pattern.
I was wondering if this is just a display issue or it rather reflects
some mismatch in actual tissue classification with consequential
errors
in the generated values of thickness and volumes as well?
If so, is there any way I can correct for this?
Thank you in advance,
Antonio
Antonio Gallo, MD
NIB-NINDS-NIH
10 Center Drive
Building 10, Room 5B16
Bethesda, MD, 20892 - USA
ph #: 001-301-402.6391
fax #: 001-301-402.0373
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