Hi Sam
usually this means that the cerebellum is too far from isocenter and hence has low SNR/more distortion. If you can place your subjects higher in the scanner that might help.
For existing data try putting some control points in cerebellar wm or brainstem. That might help
cheers Bruce
On Mon, 1 Aug 2016, Sam Mathias wrote:
Dear list, I'm interested in measuring cerebellar volumes using freesurfer. However, the automatic segmentation (aseg) seems to be doing a poor job of capturing the whole structure for many subjects. Specifically, it is chopping off the bottom of the cerebellum. Here is an example:
https://drive.google.com/open?id=0B68CY3v4cg7tS0hSNkVVMWNiZV8xYWR2eTJQQlhFe VM0Q2Jn
The issue seems to be when the cerebellum is very close to the bottom of the image, as is the case in many of our scans. Has anyone encountered similar issues with cerebellum segmentation, and if so, have any advice about how to improve it?
Many thanks,
-- Samuel R. Mathias, Ph.D. Associate Research Scientist (ARS) Neurocognition, Neurocomputation and Neurogenetics (n3) Division Yale University School of Medicine 40 Temple Street, Room 694 New Haven CT 06511 http://www.srmathias.com