Hi Sheeba, Ged and others,
from previous experience I can tell that "images looking fine" does not
mean that everything is OK with your data. As already suggested, I would
also inspect your ResMS images - they will tell you whether the GLM fitted
your data well, and if not, where you had a bad fit. If you are unlucky,
then your quality of fit will vary by an order of magnitude across your
image.
You should track down the source of this error very carefully, but
this can be tricky: equipment brought into the scanner room, RF shielding
problems, subject movement, coil/scanner problems. In our lab, it turned
out to be a stability problem of the head coil, which was not detected by
routine quality checks.
Volkmar
On Mon, 12 Feb 2007, Ged Ridgway wrote:
> I'm afraid I can't think of a good reason why the RPV would look peculiar if
> all the other images look fine. You may or may not be reassured to hear that
> this image isn't actually used by SPM, only the global smoothness estimate is
> used for RFT/FWE correction -- see this thread:
>
> http://www.jiscmail.ac.uk/cgi-bin/webadmin?A2=ind0612&L=SPM&P=8750
>
> Also, note that if you use FDR correction then neither of the global
> smoothness or local roughness estimates will be used.
>
> Having said that, the stripes in RPV might indicate a problem with your data
> (e.g. motion, as Torben suggested) that would be better solved than avoided.
>
> Hope this helps,
> Ged.
>
>
>
--
Volkmar Glauche
-
Department of Neurology [log in to unmask]
Universitaetsklinikum Freiburg Phone 49(0)761-270-5331
Breisacher Str. 64 Fax 49(0)761-270-5416
79106 Freiburg http://fbi.uniklinik-freiburg.de/
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