1. A method for segmenting an image, comprising a processor for performing steps of the method, comprising the steps of: performing an initial segmentation of the image to produce a previous segmented region; segmenting iteratively the image using a spatial random walk based on a shape prior of the previous segmented region to produce a next segmented region; comparing the next segmented region with the previous segmented region; repeating the segmenting and the comparing until the previous and next segmented regions converge; and selecting the next segmented region as a final segmented region.