a method for segmenting an anatomical image , including : receiving a patient anatomical image ; receiving a baseline anatomical image having pre - segmented labels , wherein the pre - segmented labels identify regions of interest in the baseline anatomical image ; aligning the patient anatomical image with the baseline anatomical image to produce a transformation that when applied to the pre - segmented labels roughly identifies regions of interest in the patient anatomical image that correspond to the regions of interest in the baseline anatomical image ; and updating the pre - segmented labels , which have been deformed by application of the transformation , with a new transformation that minimizes the likelihood of intensity distributions within the regions of interest of the patient anatomical image to produce a gradient image that better identifies the regions of interest of the patient anatomical image .