Here is the function that calculates the folding index and intrinsic curvature
index of the surface -
https://github.com/freesurfer/freesurfer/blob/dev/utils/mrisurf_metricProperties.cpp#L11335
int MRIScomputeCurvatureIndices(MRIS *mris, double *pici, double *pfi)
{
int vno;
VERTEX *vertex;
double k1, k2, ici, fi, area, Kmax, Kmin;
ici = fi = 0.0;
for (vno = 0; vno < mris->nvertices; vno++) {
vertex = &mris->vertices[vno];
if (vertex->ripflag) {
continue;
}
if (vno == Gdiag_no) {
DiagBreak();
}
k1 = (double)vertex->k1;
k2 = (double)vertex->k2;
area = (double)vertex->area;
if (vertex->K > 0) {
ici += area * (double)vertex->K;
}
Kmax = (double)fabs(k1);
Kmin = (double)fabs(k2);
fi += area * Kmax * (Kmax - Kmin);
}
*pfi = fi / (4.0 * M_PI);
*pici = ici / (4.0 * M_PI);
return (NO_ERROR);
}
From: [email protected]
<[email protected]> On Behalf Of littlepotato
Sent: Friday, August 2, 2024 5:40 AM
To: [email protected]
Subject: [Freesurfer] Inquiry on Calculation Methods for Folding Index and
Intrinsic Curvature Index in mris_anatomical_stats
External Email - Use Caution
Dear FreeSurfer Support Team,
I am writing to inquire about the specific methods and formulas used by the
mris_anatomical_stats function in Freesurfer to calculate the Folding Index and
Intrinsic Curvature Index for each label based on annotation files. Could you
please provide detailed information on: the algorithms or mathematical formulas
used to calculate the Folding Index and Intrinsic Curvature Index for each
label.
If there are any available documentation, publications, or example commands
illustrating these calculations, I would greatly appreciate your sharing them.
Thank you for your assistance.
Best regards,
Amber Lin
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