[Brains-users] Gyrification index

[Greg Harris]

Roberto,

The short answer is no, brains2 doesn't produce a Gyrification Index.

The best we can do in brains2 is a GTSurface workup.  After you create your
left and right surfaces with the Workup > Run Surface ... panel as directed
in the manual, you can Measure Surface Mask (b2 measure GTSurface mask)
which will produce measures like
  
   FundalSumArea 48339.711333774794184
   FundalMeanCurvature -0.097746881788291
   FundalStdDevCurvature 0.087318902788583
   GyralSumArea 53227.931754728640954
   GyralMeanCurvature 0.074606313229215
   GyralStdDevCurvature 0.052893375664620
   TotalSumArea 101567.643088503435138
   FundalMeanDepth 1.741774498054365
   GyralMeanDepth 1.884058467992384
   TotalMeanDepth 1.816340385490125

along with some others you should ignore.  Your mask will focus the surface
measurement on a region of interest.  Curvatures of 0.0000 indicate flat,
negative is concave, positive is convex.  Depths are the distance from
surface vertices to white matter;  since the surface follows a path midway
through the gray mantle, brains2 depth is an index.

The GTSurface workup commands are not built under SunOS and MacOSX.  You
will need to install brains2 on a Linux machine.

On the other hand, a FreeSurfer workup will offer you these measures:
MeanCurvature, GaussianCurvature, FoldingIndex, CurvatureIndex.  Both of
these indices seem to be highly correlated with the sum of surface area for
the region.

The brains2 curvatures correspond to statistics of the MeanCurvatures,
their means and standard deviations on the given mask region of interest.

Greg Harris


On 7/2/08 4:52 AM, "Roberto Roiz Santiáñez" <rroiz at humv.es> wrote:

> 
> 
> Hello
> 
> Does anyone know whether it is possible to calculate the Gyrification
> Index with BRAINS2
> 
> Regards



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