A processing system for and a method of segmenting a physiological image is provided. Once the physiological image is received, extrinsic data defining extrinsic regions is further received. Additionally, intrinsic data defining at least one intrinsic region, each intrinsic region corresponding to one extrinsic region is received. A primary modification is performed, where a shape and size of at least one extrinsic region having a corresponding intrinsic region is modified based on a shape and size of the corresponding intrinsic region, to form a modified extrinsic data. The physiological image is segmented into segmented regions based on the modified extrinsic data, each segmented region which has a corresponding intrinsic region representing a primary modification based on the corresponding intrinsic region.