Pectinate line

Abstract: PURPOSE: To evaluate the value of magnetic resonance (MR) imaging with a flexible surface coil in predicting the resectability of tumors in the lower rectum and the feasibility of sphincteral salvage. MATERIALS AND METHODS: In a prospective study, 61 patients with histologically proved primary adenocarcinoma of the lower or middle third of the rectum (<12 cm from the pectinate line) were examined at double-contrast-material–enhanced MR imaging with a circular polarized flexible surface coil. RESULTS: Assessment of anal sphincteral infiltration at MR imaging was excellent, with a specificity of 98% and a sensitivity of 100%. In the determination of tumor infiltration into adjacent organs (T4), the specificity was 100%, and the sensitivity was 90%, with surgical and histologic findings as the standards. While MR imaging showed negative nodes in 40 patients (stage N0 at MR imaging), histologic examination showed negative nodes in 27 patients and positive nodes in 34. At MR imaging, sensitivity was 68%, and s...

Abstract: To define the anatomy of the distal anorectal myenteric plexus more clearly, specimens from this region obtained at autopsy from 25 patients ranging from premature infants to children six years of age were studied. A distal zone characterized by a paucity of ganglion cells and the presence of nonmyelinated nerve trunks was identified. This zone is similar in appearance to areas of hypoganglionosis occurring in association with various forms of Hirschsprung's disease. The extent of this zone is quite variable but tends to increase slightly with age. It may extend up to 2.5 cm. proximal to Hilton's line or 2 cm. proximal to the pectinate line. In performing a rectal biopsy for the diagnosis of Hirschsprung's disease care must be taken to remain proximal to this zone. Interpretation of the rectal biopsy should not rest solely upon the identification of ganglion cells but must include an evaluation of the entire morphology of the myenteric plexus.