Thank great helps from the group. I have a related issue. In my images some
gray matters at the top of medial wall is lass than 60, so that these small
areas are not included in gray matter. This may be due to the shadow of RF
coil. Can I fix it by either decrease the threshold of gray matter or manually
include these small areas?
Thank you again,
Xin
Bruce Fischl
Mon, 09 Jul 2007 15:08:20 -0700
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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