Staging of rectal carcinoma using MR double surface coil, MR endorectal coil, and intrarectal ultrasound: correlation with histopathologic findings.

OBJECTIVE Our goal was assessment of the preoperative staging of rectal carcinoma with MR with double surface coil, MR with endorectal coil, and intrarectal ultrasound (IUS) as correlated with histopathologic findings. MATERIALS AND METHODS Fifteen patients with rectal carcinoma had preoperative evaluation using intrarectal ultrasound (all 15 patients), MR with double surface coil alone (6 patients), and MR with double surface coil combined with endorectal surface coil (9 patients). The results of the preoperative staging were correlated with the histopathologic findings. RESULTS IUS correctly staged the depth of bowel wall invasion in 10 of 15 patients, understaged 4, and overstaged 1. MRI correctly staged 10 of 15 patients. Without the endorectal surface coil, three of six were correct, and with endorectal surface coil seven of nine. MR with the endorectal surface coil is able to show the rectal wall in more detail than the double surface coil. CONCLUSION Endorectal surface coil MRI provides increased detail of the rectal wall, leading to better delineation of its different layers. This may lead to better staging results than with other MR techniques. The results with endorectal MRI probably equal those of IUS for staging small tumors in the rectal wall. MR with the double surface coil gives additional information about tumor spread in more advanced cases.