ANATOMY OF RADICAL PROSTATECTOMY AS DEFINED BY MAGNETIC-RESONANCE-IMAGING

Purpose: We examined and defined anatomical structures relevant to rad ical prostatectomy using magnetic resonance imaging. Materials and Met hods: Before radical prostatectomy, 15 men underwent high-resolution m agnetic resonance imaging studies of their pelvic floors (fast spin ec ho, T2 weighting of 3- to 4-mm. contiguous or overlapping slices) in a xial, coronal, and sagittal planes. Results: Pubovesical ligaments, ra ther than the commonly reported puboprostatic ligaments, were observed attaching the bladder-prostate unit to the pubis. We suggest that the part of the urethra that extends from the apex of the prostate to the bulb of the penis, which is surrounded by the striated sphincter, sho uld be termed the sphincteric urethra rather than the membranous ureth ra. Further, we found no evidence that supports the traditional concep t of a urogenital diaphragm. The lower part of the striated urethral s phincter was flanked on its sides by the anterior recesses of the isch ioanal fossae. The portion of the levator ani, which we have termed th e puboanalis sling, flanked the apex of the prostate. The most anterom edial portion of this sling inserts into the perineal body and should be termed the puboperinealis. The terminal part of the gastrointestina l tract (the part continued beyond the levator ani) should be termed t he anal canal, not the rectum, as used frequently in the urologic lite rature. Therefore, the initial plane of dissection in radical perineal prostatectomy passes along the anterior portion of the anal canal, no t the rectum. Conclusion: We used magnetic resonance imaging to study male pelvic floor and perineal anatomy without the artifact of dissect ion. This study allowed us to devise a more precise nomenclature with respect to radical prostatectomy and, in so doing, to provide a better understanding of both the retropubic and the perineal operations.