SURFACE AND VOLUME REGISTRATION OF BRAIN MAGNETIC RESONANCE IMAGES

3D volumetric registration of brain images is particularly challenging in cortical regions due to their high complexity and folding. Here we develop a new combined algorithm for surface and volume registration of brain MR images. Our method proceeds in 3 steps: First, we segment the cortices and use the Freesurfer registration algorithm to obtain a map between cortical surfaces. This matching is extended to the whole brain volume by computing an harmonic map between the brain manifolds such that their surfaces remain aligned. Finally, the registered images from the first two steps are used as input to a 3D Riemannian fluid algorithm in order to obtain an accurate matching of the subcortical structures. The results show significant improvement over using fluid registration alone.