Connectivity-based parcellation of the cortical surface using q-ball imaging

This work exploits the idea that each individual brain region has a specific connection profile to create parcellations of the cortical surface using MR diffusion imaging. The parcellation is performed in two steps. First, for each vertex of a cortical surface mesh, a connection profile is computed using a probabilistic tractography framework. The tractography is performed from q-ball fields using regularized particle trajectories. The raw connectivity matrix is smoothed over the surface to account for a reasonable uncertainty on the tractography result. A cortical surface parcellation in 36 large gyri is used to reduce the connectivity profiles dimension. For each vertex, interconnection with the gyri is determined, leading to a connectivity profile made up of only 36 connection strengths. These profiles are clustered on a gyrus by gyrus basis using a k-means approach including spatial regularization. The reproducibility of the results is studied for three subjects.