Hi Pam
Yes, that’s pretty accurate.
Cheers
Bruce
From: freesurfer-boun...@nmr.mgh.harvard.edu
<freesurfer-boun...@nmr.mgh.harvard.edu> On Behalf Of Pam Garcia
Sent: Thursday, September 24, 2020 9:40 PM
To: freesurfer@nmr.mgh.harvard.edu
Subject: Re: [Freesurfer] parameterization template and the vertex in the pial
surface
External Email - Use Caution
Thanks for your response Bruce, just to clarify
If I understood, the wm surface is created using a surface deformation
procedure that adaptively determined the MR intensity of the boundaries in
question at each point in the cortex. Next a sphere from the wm inflated
surface is computed, warps the sphere into a 2-D file containing the curvature
and convexity patterns of the subject, and then registers the 2D file with a
reference (parameterization template). This is executed to ensure that the
curvature and convexity patterns are aligned with a generic reference template.
The mean and the variance of curvature and convexity from the smooth and
inflated surface are used in order to do more robust the register. Finally, the
pial surface is created by expanding the white matter surface so that it
closely follows the gray-CSF intensity gradient, keeping the same topology
(number of vertex, edges, faces) and the vertex index is preserved. Finally,
the vertex of the wm and pial surface are mapped in a common space and is here
where we obtained vertex correspondence across the subjects.
Thanks
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