Role of virtual computed tomographic colonography in patients with colorectal cancers and obstructing colorectal lesions

PURPOSE: The aim of this study was to assess the ability of computed tomogr aphic colonography to diagnose colorectal masses, stage colorectal cancers, image the proximal colon in obstructing colorectal lesions, and evaluate t he anastomoses in patients with previous colorectal surgery. METHODS: We pr ospectively performed computed tomographic colonography examinations in 34 patients (20 males; mean age, 64.2; range, 19-91 years): 20 patients had co lorectal masses (defined at endoscopy as intraluminal masses 2 cm or larger ), 7 patients had benign obstructing colorectal strictures, and 7 patients had a prior colorectal resection. Final tumor staging was available in all 16 patients who had colorectal cancers and 15 patients were referred after incomplete colonoscopy. The ability of computed tomographic colonography to stage colorectal cancers, identify synchronous lesions in patients with co lorectal masses, and image the proximal colon in patients with obstructing colorectal lesions was assessed. RESULTS: Computed tomographic colonography identified all colorectal masses, but overcalled two masses in patients wh o were either poorly distended or poorly prepared. Computed tomographic col onography correctly staged 13 of 16 colorectal cancers (81 percent) and det ected 16 of 17 (93 percent) synchronous polyps. Computed tomographic colono graphy overstaged two Dukes Stage A cancers and understaged one Dukes Stage C cancer. A total of 97 percent (87/90) of all colonic segments were adequ ately visualized at computed tomographic colonography in patients with obst ructing colorectal lesions compared with GO percent (26/42) of segments at barium enema (P < 0.01). Colonic anastomoses were visualized in all nine pa tients, but in one patient, computed tomographic colonography could not dis tinguish between local tumor recurrence and surgical changes. CONCLUSION: C omputed tomographic colonography can accurately identify all colorectal mas ses but may overcall stool as masses in poorly distended or poorly prepared colons. Computed tomographic colonography has an overall staging accuracy of 81 percent for colorectal cancer and is superior to barium enema in visu alizing colonic segments proximal to obstructing colorectal lesions.