Implicit surface registration with surface-oriented anisotropic deformation field smoothing

This paper introduces a variant of the Demon´s algorithm with an anisotropic smoothing term designed for the registration of surfaces with significant conformal differences. Because of the chosen implicit surface representation, the deformation field at each iteration can be easily defined with respect to the evolving surface. Anisotropic smoothing is performed preferentially in the tangent plane to the surface, preserving local, complex deformations. This method is applied to the registration of consecutive neonatal cortical surfaces from MR images acquired at 30 and 40 week gestational ages. Our method preserves the emergence of small, new folds, while greatly reducing noise in the resulting deformation field.