Dear SPM:
Has anyone looked into how to decide objectively on the performance of
various structural sequences for VBM? I have read over the recent paper by
Deichmann for example and he cites improvements in CNR and SNR, but to some
extent the evidence for the goodness of a sequence is visual ("it looks
good"). Are there any tools for quantitating this goodness? Is there a
measure for deciding when the bias field or inhomogeneity is minimized?
Let's say i have a T1 sequence and a T2 sequence. I segment each to their
respective templates and find that the T2 sequence shows narrower Standard
deviations for all three compartments (gray, white and CSF) in the
segmentation printout. Does this suggest that this sequence was better
because it produced better separated tissue clases?
thanks,
Darren
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Darren R. Gitelman, M.D.
Cognitive Neurology and Alzheimer¹s Disease Center
Northwestern Univ., 320 E. Superior St., Searle 11-470, Chicago, IL 60611
Voice: (312) 908-9023 Fax: (312) 908-8789
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