Staging of colon carcinoma using water enema CT.

OBJECTIVE: To determine the accuracy of water enema CT (WECT) for staging colon carcinoma.
MATERIALS AND METHODS: Thirty patients with colon cancer, diagnosed by barium enema and/or colonoscopy, underwent preoperative WECT. Dynamic contrast enhanced CT studies were performed after rectal administration of < or = 2 L lukewarm tap water. Images were prospectively analyzed for depth of tumor invasion, nodal involvement, and distant metastases by investigators blinded to the results of barium enema and colonoscopy. Surgical/pathologic proof was obtained in all cases.
RESULTS: Using WECT, 23 of 30 patients were correctly staged. Correct staging occurred in 2 of 2 patients with Stage A, 3 of 3 patients with Stage B1, 6 of 9 patients with Stage B2, 1 of 2 patients with Stage C1, 5 of 8 patients with Stage C2, and 6 of 6 patients with Stage D tumors. Of the patients incorrectly staged, 4 were understaged and 3 were overstaged; all were due to errors in predicting lymph node involvement. Sensitivity and specificity for evaluating nodal involvement were 60 and 79%, respectively.
CONCLUSIONS: Water enema CT allows for accurate depiction and staging of colon carcinoma. Aqueous distention of the colon avoids artifacts seen with positive contrast agents yet allows accurate evaluation of the bowel wall and pericolonic structures.