Segmenting cortical gray matter for functional MRI visualization

We describe a system that is being used to segment gray matter and create connected cortical representations from MRI. The method exploits knowledge of the anatomy of the cortex and incorporates structural constraints into the segmentation. First, the white matter and CSF regions in the MR volume are segmented using some novel techniques of posterior anisotropic diffusion. Then, the user selects the cortical white matter component of interest, and its structure is verified by checking for cavities and handles. After this, a connected representation of the gray matter is created by a constrained growing-out from the white matter boundary. Because the connectivity is computed, the segmentation can be used as input to several methods of visualizing the spatial pattern of cortical activity within gray matter. In our case, the connected representation of gray matter is used to create a representation of the flattened cortex. Then, fMRI measurements are overlaid on the flattened representation, yielding a representation of the volumetric data within a single image.