for the continuous curvature you can just cite the FreeSurfer paper, or recon1/2). For the discrete curvature I think Rudolph Pienaar published something on it. Some of the curvature indices are from David Van Essen's papers, and the volume/area calculation is Anderson M. Winkler's paper


On Mon, 9 Sep 2019, Loske, Philipp wrote:

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Hi you two,

thank you very much for your quick reply! Just two short followup questions:

@Bruce: Is this published in any paper or documentation so I can cite it?

@Doug: Has this method been implemented with the last release of FS in 6.0.0
or already before in 5.3.0 (I'm still using this version)?


      For cortical volume we compute  vertex-wise volume based on
      dividing each obliquely truncated   trilateral pyramid into
      three tetrahedra. Based on Anderson M. Winkler's   srf2vol
      matlab script.
On 9/6/2019 10:22 AM, Bruce Fischl wrote:
Hi Philipp

I'll leave the volume question to Doug. The curvatures are estimated
by fitting a second order polynomial to the local height function in
the tangent bundle then computing the Hessian using the white
(gray/white boundary) surface. We also have some discrete measures of
curvature that uses the Gauss-Bonnet theorem, but those aren't run by

On Fri, 6 Sep 2019, Loske, Philipp wrote:

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Hello FreeSurfer Developers,

I have a question about references and descriptions to all the
features available in aparc.stats, extracted from structural MRI. I am
all the different features (SurfArea, GrayVol, ThickAvg, ThickStd,
GausCurv, FoldInd, CurvInd) for the 68 cortical regions available from
Desikan Kiliany atlas. I have been trying to find references to how
features are measured or derived, but couldn't find a proper list of
references to each of the features. I a lot of references
with detailed descriptions on surface reconstruction and how cortical
thickness is measured, but couldn't find a detailed explanation on the
features, especially curvature values.

I think I have been able to find out what each of the measurements
mean and
how they are calculated in principle, through searching the internet a
but with no direct link to FreeSurfer. For instance, I know you can
the curvature values from the principle curvatures, but how does FS
those form the reconstructed Surface? And which one of the two
surfaces does
it use? White-pial or pial-csf surface? I found
helpful, but it says for example that a new way of measuring cortical
was implemented in FS 6.0.0, so does that mean for previous versions
FS uses
the Thickness x SurfaceArea method? Would be great if you can help me
this, or point me to the correct website I might just have missed
during my

Best wishes


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