| I am trying to segment images prior to normalising the tissue maps
| separately. However, the segmented grey matter maps sometimes contain a
| little bit of scalp. Is it possible to tweak the segmentation to avoid
| this, or to remove it during the normalisation by some kind of masking?
The <Xtract Brain> utility within SPM99b can be used to clean up the grey
and white matter segments. Specify the xxx_seg1.img and xxx_seg2.img files, and
it will produce a brain__xxx.img file, that contains values of one for brain
and zero otherwise (after taking scalefactors into account). You can then
multiply xxx_seg1.img by brain_xxx.img using the <ImCalc> button (and
an expression something like "i1.*i2").
Regards,
-John
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