Dear group,
I am having no luck in obtaining clean segmentations, in particular much
of the retrobulbar anatomy is being included with the gray matter, which
alters my gm/wm/csf proportions. I have followed advice from the archives
regarding creating my own study-specific apriori maps
(the 'make_template.m' script), with even worse results (I am using 30
subjects, which should be enough to generate usable maps).
My mprage scans were obtained on a 3T scanner, and I understand that the
apriori maps included with SPM are based on scans from a 1.5T scanner.
Could this difference be responsible for the poor gray segmentation I am
seeing? Or is this related to the mprage sequence (or both the sequence
and field strength)? Furthermore, is anyone able to share any advice in
creating study-specific apriori maps.
George P Thomas, Jr.
University of Kansas Medical Center
Brain Aging Project
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