in our experience the 12 and 32 channel coils are much easier to process
than the 8 channels, but it really depends on the coil geometry
Bruce
On Wed, 28
Mar 2012, Tetiana Dadakova wrote:
Do you think 32ch coil would be better? We also have data with the
same scanner and same sequence, but 32ch coil. Although, visually,
32ch data is much more inhomogenious, especially in occipital part (it
is too bright). We were afraid that wm there would be hard to
distinguish from gm and that therefore the thickness would be too
underestimated, that is why we decided to use 8ch data.
Tanja.
On Wed, Mar 28, 2012 at 3:28 PM, Bruce Fischl
<fis...@nmr.mgh.harvard.edu> wrote:
it may also be the 8 channel coil, which can make things hard, particularly
near the vertex. Dielectric effects are usually still pretty modest at 3T
although they are visible. I think control points would be your best bet.
cheers
Bruce
On Wed, 28 Mar 2012, Tetiana Dadakova wrote:
Hello Bruce. Thank you for your reply.
I am not sure why the wm is too dark. Our population is very stressed
(burnout) people vs controls, scanner GE Discovery MR750 3.0T, coil
8ch, we use BRAVO sequence with 1x1x1mm voxels.
Compared to the dataset I worked with before (from 1.5T scanner), here
wm is omitted much more often (and often control points do not work),
but also sometimes some brighter portions of gm are included as wm. I
think the problems can be caused by higher field inhomogeniety with
higher static magnetic field, but I am not sure.
Tanja.
On Wed, Mar 28, 2012 at 3:00 PM, Bruce Fischl
<fis...@nmr.mgh.harvard.edu> wrote:
Hi Tanja
why is the wm too dark? Can you tell us something about your data
(population, coil, scanner, etc...)?
cheers
Bruce
On Wed, 28 Mar 2012, Tetiana Dadakova wrote:
Hi Louis,
thank you very much for your reply.
The problem with our data is that wm is too dark sometimes to use
control points (intensity is too inhomogenious in some parts). That's
why we would like to have the opportunity to just draw the wm where
needed. But for some reason it doesn't correct the surfaces.
Best wishes,
Tanja.
On Tue, Mar 27, 2012 at 4:23 PM, Louis Nicholas Vinke
<vi...@nmr.mgh.harvard.edu> wrote:
Hi Tanja,
I would recommend you try using some control points. Place one or two
just
inside the wm surface near that wm finger which is not being included,
and
then possibly one or two control points carefully placed along the wm
finger
on voxels with the highest intensity (in the middle it looks like).
Not
sure what the other coronal slices look like, but you may want to do
something similar on other slices.
-Louis
On Tue, 27 Mar 2012, Tetiana Dadakova wrote:
Dear FS list,
After recon-all -all we had some wm missing in temporal part of the
brain (fig. wm_missing1). We edited wm.mgz and re-run recon-all
-autorecon2 -autorecon3. After this, the wm.mgz looks as fig.
wm_missing2, but the surfaces still look as fig. wm_missing1.
What can be the reason that wm.mgz edits didn't affect the surfaces?
Thank you,
Tanja.
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