2 METHOD 2 Brain Mask PD Image Generate Initial Brain

A robust fully automatic method for segmenting the brain from head MR images has been developed , which works even in the presence of RF inhomogeneities. It has been successful in segmenting the brain in every slice from head images acquired from several diierent MRI scanners, using different resolution images and diierent echo sequences. The method uses an integrated approach which employs image processing techniques based on anisotropic lters and \snakes" contouring techniques, and a-priori knowledge, which is used to remove the eyes, which are tricky to remove based on image intensity alone. It is a multi-stage process, involving rst removal of the background noise leaving a head mask, then nding a rough outline of the brain, then reenement of the rough brain outline to a nal mask. The paper describes the main features of the method, and gives results for some brain studies.