Dear everyone,
I tried the spatial normalization and it works well.
Although I do not know, how I can disable the
nonlinear wraping ?
The segmentation is not generaly bad, only segmented
areas in upper regions are incorect.(see example.tif)
I do not think, that any function is not working,
because there are no error messages during
segmentation. Exists any limitation for segmenting ?
Thanks
Gregor
> > If your data are not already spatially normalised,
> > then
> > the first thing that the segmentation in SPM does
> is
> > to
> > attempt a 12-parameter affine registration to one
> of
> > the
> > template images. This is so that it can overlay
> the
> > prior probability images of GM, WM and CSF. If
> this
> > stage
> > fails, then the segmentation can go horribly
> wrong.
> >
> > You could test this by spatially normalising the
> > problematic
> > images (after disabling the nonlinear warping).
> If
> > this is
> > the problem, then try first reorienting the images
> > via the
> > Display button, so that they are transverse, with
> > the
> > origin near the AC. Once the spatial
> normalisation
> > is
> > working, then there should be fewer problems with
> > the
> > segmentation.
> >
> > Good luck,
> > -John
> >
> > | I use SPM'99 to segment 3-d gradient-echo
> > datasets.(TR
> > | = 19ms, TE = 4,4 ms, flip = 8, FOV = 23 cm,
> > thickness
> > | 3mm, gap = 0, slices = 60). I get good results,
> > when I
> > | use the PD-weigthed template. Usually the
> > segmentation
> > | is almost perfect. Sometimes (on some heads) the
> > | segmented areas are much too small, especialy in
> > upper
> > | regions. I tried quite a lot to find the reason
> > for
> > | that but I can't find a systematic. I have a
> > couple of
> > | ideas: Does the ratio between FOV and head size
> > have
> > | any influence on the segmentation ? How does the
> > | position of the head (i.e. rigth-left) influence
> > the
> > | quality of the segmentation ? The results are
> > better
> > | if the first 5 slices(head first) of the dataset
> > are
> > | above the skull, but this is difficult to
> > implement
> > | into clinical routine.
> > | Does anybody have an idea ?
> >
> >
>
>
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