This is because there are no tissue probability maps for non-brain
regions. The lack of these means that a modification is needed so that
the tissue probability maps are not stretched to match the whole head.
The original modification was to exclude low intensity regions (mostly
air, but on some sequences this also includes CSF). Since then, there
should be a new modification, which should preserve the CSF in your
tissue class images (based on a mask derived from the initial affine
registration). This modification should be among the latest updates for
SPM5.
Best regards,
-John
-----Original Message-----
From: SPM (Statistical Parametric Mapping) [mailto:[log in to unmask]]
On Behalf Of Matthew L. Senjem
Sent: Tuesday, September 12, 2006 11:01 PM
To: [log in to unmask]
Subject: [SPM] CSF segmentation in SPM5 versus SPM2
Dear John and list,
We have noticed that SPM5 does not correctly identify CSF inside the
ventricles of our MPRAGE scans, probably because CSF has an intensity
distribution similar to that of background.
SPM2, on the other hand, does correctly segment the CSF inside the
ventricles.
Has anyone else noticed this?
Any suggestions for improving the results?
Thank you in advance for any help you may be able to offer.
Best wishes,
Matt.
--
Matthew L. Senjem
Analyst Programmer - Imaging Systems
Mayo Clinic and Foundation
Mail Code: RO_CE_09_IMAGING
200 First St. SW
Rochester, MN 55901
[log in to unmask]
Fax: 507-284-9778
Phone: 507-538-0764
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