Dear Crisitna,
> I would like to create the customized prior probability maps, I read from
one email > (15 Jan 2002) that
> >5) Normalise the images by estimating a set of affine transformation
parameters
> >from the unsmoothed GM. Apply these parameters to the smoothed
partitions,
> writing
> >the data with the "Template" bounding box.
> I have to normalized the clean up GM images using affine transformation,
but which > template should I use?The mean of the clean up GM images, is it
right?
At this point, you should use the apriori GM template to transform the
brains into a standardized space. I guess, your original images are oriented
differently for each subject, so, averaging at this point would not help.
To get a new template, you average the normalized brain (like point 6 in the
mail, you mentioned.).
Having this new template, you have to do the normalisation procedure again
and now, you can use your own template.
> Should I do this for WM and CSF images too?
Yes, you should apply the transformation parameters from the first
normalization (GM onto apriori\GM template) to the WM and CSF images, also.
Otherwise, if you normalise them individually, they will represent slightly
different spaces, which is not useful.
Good luck,
Karsten
----------------------------------
Karsten Specht
fMRI Section
Department of Neuroradiology
Medical Centre Bonn
Spessartstrasse 9
53119 Bonn
Germany
Phone: ++49-(0)228/90 81-178
Fax: ++49-(0)228/90 81-190
E-Mail: [log in to unmask]
WWW: http://www.mcbonn.de/Praxis/praxis15/fmri1.htm
|