Hi All-
While spm_preproc works quite well in most cases, for certain subjects, spm_preproc completely fails to produce a reasonable normalization, and instead yields a heavily distorted brain as the 'normalized' output (when the transform is applied to the anatomical via spm_write_sn). We've had two subjects for whom this is the case; one of which we scanned twice, with spm_preproc producing ridiculous output both times, although in different ways, for a total of three examples of this bizarre behavior of the algorithm.
Since I can't seem to figure out how to attach emails to this, I've arranged the screenshots in an online album:
http://imgur.com/a/AtTQ2
The order of images is:
1) sub1a anatomical image
2) sub1a normalized anatomical, from spm_preproc
3) sub1b anatomical image (from the second scan)
4) sub1b normalized anatomical, from spm_preproc
5) sub2 anatomical image
6) sub2 normalized anatomical (from spm_preproc)
7) subject anatomical that produces normal spm_preproc output
8) an example of the typical output of spm_preproc in our experience
Please let me know if anyone has had similar experiences, or has any suggestions. Could this be due to the high degree of inclination of the skull in the anatomicals that produce poor outputs?
Thanks!
|