Hi Linn
The text you cite is how we measure it. It is the signed distance each points
moves to get from the white to the inflated surface, where outwards movement is
positive (along the surface normal direction) and inwards distance is negative.
Cheers
Bruce
From: freesurfer-boun...@nmr.mgh.harvard.edu
<freesurfer-boun...@nmr.mgh.harvard.edu> On Behalf Of Linn Christin Bonaventure
Norbom
Sent: Tuesday, February 6, 2024 8:28 AM
To: freesurfer@nmr.mgh.harvard.edu
Subject: [Freesurfer] calculation of sulcal depth
External Email - Use Caution
Dear experts,
I am assessing different morphological aspects of the cortex including sulcal
depth but am struggling to understand how this is calculated in FreeSurfer. I
see that a previous correspondence
(https://www.mail-archive.com/freesurfer@nmr.mgh.harvard.edu/msg43772.html)
points to this being described on page 199 within the "Cortical surface-based
analysis II" - paper, by Fischl et al. but to my understanding it only
describes the inflation process. Is it so that as concave areas like sulci move
outward, while convex areas like gyri move inward during this process, this
movement is somehow quantified and used to calculate sulcal depth? I also see a
previous article stating that "..Freesurfer's sulcal depth measurement measures
how far a vertex moves during an inflation operation", also referencing the
same Fischl paper.
While other folding measures like LGI (MailScanner has detected a possible
fraud attempt from "secure-web.cisco.com" claiming to be
https://surfer.nmr.mgh.harvard.edu/fswiki/LGI<https://secure-web.cisco.com/1rZbD04F-L_WBb_-7dP8B298OK6uZo1zDlLneMBGyND_ivL2gPkiZTug0WyglfVkOxxiC02F2Fh9blwiaSive2lw9mQNXXar3KvM6viLVnbE0k8g7scdmmyXJnbPb5wzV7dorN16_yT8hpRYKkSnOgVJPTiYFr6imCXCw0oqSa3vw69icYlZlp0nrJEZ8CQI6THyg7T7c18tXbLwhC255w6lGcKFdcqQrkDtTxdDJ2m2rKsF8kH0AyALHcPwzFqoW5lVOAgzmbhZXo18NET-ucEVyQLZkek29qz2zU84XKJGF_9yRPSlYxRMomM5dW00gbbDpAYbhEk1jwn-WXxTb6w/https%3A%2F%2Fsurfer.nmr.mgh.harvard.edu%2Ffswiki%2FLGI>
and curvature (MailScanner has detected a possible fraud attempt from
"secure-web.cisco.com" claiming to be
https://surfer.nmr.mgh.harvard.edu/fswiki/MeanCurvature<https://secure-web.cisco.com/1bY39JsrtiDKpPFJNg4aHhIchmGuug1PSRGvTczzLFMkNC8ifemRnYXnUDdmvRVVZ4BQmPxQvIJYXoUo14A2_GWqoJNuEnMk1x13Nj6Nu8dkE12w8VdN62Wvy5k2ihHSWjarOV9aYXxP7z56hbzOv-OIIfyD4jdXX65nYsgl0gy63HZMpxvtIe7E4aREI07xP6OJiWKOkIBQcg4rhaXvSYofqQl930k1EpdawV8TMZBGr7tPI8p4Q8x99pg9LtQAkPs9_1zpMUeiIRrajetzyPwuc597BofExcrVipWR3eBC0nVk_aC7UjmoHJciUUPE-q2SMcd8zX2FMOXGT2RJfng/https%3A%2F%2Fsurfer.nmr.mgh.harvard.edu%2Ffswiki%2FMeanCurvature>)
are neatly covered, I unfortunately could not find the same descriptions for
sulcal depth. Any clarifications would be greatly appreciated.
Thank you in advance!
Kind regards Linn Norbom
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