3-DIMENSIONAL DISPLAY OF THE PELVIC STRUCTURE OF ANORECTAL-MALFORMATIONS BASED ON CT AND MR-IMAGES

Three-dimensional images of the pelvic structure of patients with anor ectal malformation (ARM) were constructed by computer graphics based o n radiographic computerized tomography (CT) and magnetic resonance (MR ) images. Organ contour data from CT images and raw MR image data were transferred to a personal computer and to a graphic workstation respe ctively. On MR image processing, organs were extracted semiautomatical ly by thresholding enclosed areas. After several steps of image proces sing, three-dimensional anatomy of each anomaly was visualized with em phasis on position and shape of the muscle complex. In control patient s without an anomaly, images showed that the rectum is supported by th e levator muscle from behind and descends along with the urethra. In t he male patient, the anal canal separates from the urethra and penetra tes through the middle of the sphincter complex to reach the orifice. In those with low-type anomaly with a fistula opening to the perineum or the vestibule, images showed the fistula descending through the ant erior portion of the sphincter complex. Images of those with a rectour ethral fistula could show the muscle complex behind the rectum and at the region where the external sphincter should be. In those with cloac al anomalies, anatomical position and the shape of three different vis cera were easily recognized, and the muscle complex was shown like tha t of rectourethral-type anomalies. This study is a new approach to the anomaly to facilitate understanding it and can assist a surgeon in pl anning a procedure. This kind of application would make it possible fo r a surgeon to consider the strategy on a display screen before the re al surgery. Copyright (C) 1995 hy W.B. Saunders Company