bookmark BET / Brain Extraction Tool Deletes non-brain tissue from an image of the whole head. BET can also estimate the inner and outer skull surfaces, and outer scalp surface, if T1 and T2 input images are of good quality. It is very robust and accurate and has been tested on thousands of data sets from a wide variety of scanners and taken with a wide variety of magnetic resonance sequences. BET uses a deformable model that evolves to fit the brain's surface by the application of a set of locally adaptive model forces. The method is very fast and requires no preregistration or other pre-processing before being applied. BET takes about 5-20 sec to run on a modern desktop computer and is freely available, as a standalone program that can be run from the command line or from a simple GUI, as part of FSL (FMRIB Software Library).