usually it's because the bias field brings the gm too low, so if you find
nearby white matter (that is *not* partial volumed) that is below 110,
putting some control points there will also move the pial surface out a
bit. Or the skull strip could have removed it. Or the topology fixer might
have done something strange. This can be checked by looking at the
?h.orig.nofix surface and seeing if it is more accurate than the ?h.orig.
If this is the case you'll need to identify and correct the topological
defect in the wm.mgz volume.
cheers,
Bruce
On Mon, 9 Jul 2007, Sebastian Moeller wrote:
Hi,
not being an expert, please take my rambling with a grain of salt. But I am
somewhat curious to learn better ways ;)
On Jul 9, 2007, at 11:03 PM, [EMAIL PROTECTED] wrote:
Message: 9
Date: Mon, 9 Jul 2007 17:01:42 -0400
From: "Wang, Xin" <[EMAIL PROTECTED]>
Subject: [Freesurfer] add the gray matter
To: "freesurfer" <freesurfer@nmr.mgh.harvard.edu>
Message-ID:
<[EMAIL PROTECTED]>
Content-Type: text/plain; charset="iso-8859-1"
Hello, Group
I need to edit the pial surface. I learned to remove points with tkmedit
from the tutorial. But how to add gray matter in the pial surface?
1) If you have nothing where gray matter should be, then check
brainmask.mgz, if this is missing gray matter, around where your problems
occur edit the bainmask.mgz volume and pick up your reconstruction from
there. (IIRC there is something in the tutorial about this)
2) If there is white matter where gray matter should be, be sure to
to check nu.mgz and brainmask.mgz at the critical parts for too high
intensity in the supposed gray matter. Either control points might helo
(unlikely) or redoing the intensity correction (and then starting again from
that point). At least for my data, acquired with surface coils, sub-optimal
intensity correction is really annoying.
ahoi & good luck
Sebastian
Thank you in advance.
Xin
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