and split. Although this topological constraint may be reasonable in the segmentation of the liver, it would certainly be undesirable when segmenting blood vessels in an MR image. An algorithm to overcome these diculties was rst introduced by

and split. Although this topological constraint may be reasonable in the segmentation of the liver, it would certainly be undesirable when segmenting blood vessels in an MR image. An algorithm to overcome these diculties was rst introduced by