The first step in the segmentation process is an affine registration to MNI
space. In SPM2, this was done by minimising the mean-squared difference
between the image and a template of the same contrast. In SPM5, a mutual
information registration to tissue probability maps is used. As there are
only tissue probability maps of GM, WM and CSF and nothing for skull, scalp
etc, then this is not always stable. Because of this, it can be a good idea
to have your origins set reasonably close to the AC, and the orientation of
the images close to that of the template data.
Best regards,
-John
On Monday 22 October 2007 15:14, Susan> <Shear wrote:
> We are able to segment T1 images including post-contrast images using
> SPM2, but segmentation is corrupted or fails in SPM5 with the post-
> contrast images. Does any one have any suggestions on how to fix this
> problem?
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