This process calculates the 3D Gyrification index by dividing the area of a cortical mesh by the area of its convex hull.
This process uses the RicGyrificationIndex program to determine gyrification index of a cortical mesh by comparing the area of the mesh to the area of its convex hull. An optional ventricle volume file can be used to remove the ventricles from both the cortical mesh and the convex hull. If a ventricle volume file is specified then it is useful to super sample the meshes to make a closer match to the edges of the ventricles.
BIG Warning ... The ventricle volume voxel space must correspond to the mesh volume.
There is also an optional transformation matrix for PeterK to scale the meshes after they have been culled by the ventricle volume.
The gyrification index is output along with the areas of the convex hull and cortical mesh. If there is a ventricle volume then culled meshes for cortex and convex hull are also output.
Click on the link below to download the file. Place it in the root BrainVISA directory. This directory should have subdirectories bin, brainvisa, include, lib, share. Run gunzip to uncompress the file. The run 'tar -xvf RicGyrificationidx.tar' to put all the files in their proper places. A ventricle volume mask file 'ventricles.ima' will be in the root directory. When you run BrainVISA, there will be an additional catagory 'ric' that will contain the plugin.
Download GyrificationIndex plugin for version 3.02 or 3.1 from NITRC (Linux only)