Yes, it is. It is confusing when you talk about area and volume since
these are not point measures like thickness (ie, what is the volume or
area of a vertex?). The area of a vertex is computed as the mean of the
adjacent triangles of the vertex. The volume is the mean of the
neighboring truncated tetrahedra. When you run mris_preproc, it will
apply a jacobian correction (like VBM). Otherwise, it operates the same
as if you had a thickness value at the vertex, ie, same GLM, etc. Make
sure to use permutation for correction of multiple comparisons.
On 2/21/2022 12:13 PM, Laura Willers de Souza wrote:
External Email - Use Caution
Hello FreeSurfer Developers,
I would like to know if it is correct to perform volume and surface
area analysis using freesurfer's GLM!?
In several mailing list questions I have already seen instructions for
performing these types of analysis. But I understand that freesurfer
does vertex-wise analysis in the 2D surface space. So, it is not clear
to me how it is possible to evaluate a 3D measurement, as volume, with
a 2D method!?
I've also read that surface area analysis via vertex-wise analysis
doesn't make much sense. The best would be to do ROI-based analysis.
Can you explain that to me?
Thanks in advance!
*Laura Willers de Souza *
Master Student in Biochemistry
Zimmer Lab - Federal University of Rio Grande do Sul
- Porto Alegre/RS - Brazil
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