The system has been applied to angiogram images of vessels in the pelvis and thigh. Although the system can detect vessels within single images, it cannot yet provide three-dimensional information about the shapes. It is hoped that by applying the algorithm to angiograms taken from many angles around the patient, the results can be combined to obtain the three-dimensional structure of the vessels. An algorithm like that presented in [3] can then be used to measure the diameters vessel precisely. Such measurements are helpful to physicians in diagnosing and treating patients.