The surface area is the actual area of the surface. I think you may be thinking of the jacobian, which measures the amount of stretching needed to register with the surface atlas. Total cortical volume is available from the "header" of the aseg.stats file, and that is a surface-based measure. As of version 5, we stopped reporting the volume-based cortical volume measure.
doug
On 9/29/10 9:57 PM, Jeff Sadino wrote:
Hello,
As I understand it, the surface area measure is not a real surface area measure. It is more a measure of how much the brain has to be stretched in order to get into a common space. My question is that if the cortical volume is calculated by multiplying the thickness and the surface area (right?), then is it a real volume that can be compared between subjects?
Also, is it is more accurate to use the cortical volume measures from the aparc files rather than the aseg files, since the aseg files overestimate the white matter due to the manual tracing it is based on?
Thank you, Jeff _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer