Hello,
I've got a question about cortical surfaces in the ventral regions below
the basal ganglia and about tkregister output quality control.
I'm using the latest version of freesurfer:
freesurfer-Linux-centos4_x86_64-stable-pub-v3.0.5
1) In the majority of my data sets, white matter surfaces near the
basal ganglia rise dorsally to include large volumes of the basal
ganglia (putamen, nucleus accumbens, both hemispheres) - attached
image. This results in inaccurate cortical volumes and thickness
estimates from the surface based data for these regions. How can I
compensate for these surface problems in order to get the best possible
estimate of total cortical volume? I've tried editing the white matter
manually and this has little effect on the locations of white matter
surfaces in the basal ganglia.
2) I'm having a difficult time knowing how to determine if the
talairach registration is good enough for each data set, and judging the
quality of my manual edits using tkregister. Could you post an
additional series of tiff or jpg images (multiple parasagittal, coronal,
horizontal) showing how cortical surfaces and movable volumes are
supposed to align in each plane? It would help to see examples of
registrations that are "perfect", "good enough not to edit", and "bad
enough to require adjustment".
Thanks very much!,
Paul