The thickness is an average of two numbers. One is the distance from a white surface vertex to the pial surface along the normal to the white. The other is the distance from the pial to the white along the normal to the pial.
Volume (in v6) is computed as the volume of a truncated tetrahedron. Prior to v6 it was surface area times thickness
On 04/10/2017 12:24 PM, John Anderson wrote:
Dear Freesurfer experts, I highly appreciate if anybody clarify how Freesurfer calculate cortical thickness and gray matter volume. If the cortical thickness of e.g. precentral gurus is measured as the closest distance from the gray-white boundary to the gray-CSF boundray at each vertex on the tessellated surface (Fischl and Dale. 2000). How the gray matter volume for the precentral gyrus was measured?
Thank you for any clarification!
John
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