Dear Carles,
>we would like to find correlation between the difference of pre
>and post surgery SPECT brain perfusion images and the result of
>some neurological tests.
I think your best bet would be to compare pre and post images
to a set of normal SPECT images (32 sounds good) of a similar
age range.
Then use the perfusion deficits (i.e. lesion volumes) that SPM
detected in a correlation analysis with your neurological
test scores, in any statistical package.
Alternatively, you could try to do a conditions and covariates
analysis where your conditions would be pre and post surgery
and your covariates of interest would be the neurological test
scores.
>Are these differences affected by normalization procedure?
If your images do not have large abnormalities, normalisation
will have no detrimental effect on them but if there are large
abnormalities you should avoid non-linear normalisation.
Best wishes,
Emmanuel
______________________________________________________________
Emmanuel A Stamatakis PhD Tel: +44 (0) 1223 766454
Centre for Speech and Language Fax: +44 (0) 1223 766452
Department of Experimental Psychology
Cambridge University
Downing Street
Cambridge CB2 3EB
U.K. http://csl.psychol.cam.ac.uk
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