Diagnostic performance of computed tomography colonography in symptomatic patients and in patients with increased risk for colorectal disease.

PURPOSE: To evaluate the diagnostic performance (colorectal lesions) of computed tomography (CT) colonography in 111 patients, a majority of whom were at high risk for colorectal neoplasia. MATERIAL AND METHODS: After bowel preparation, CT colonography was performed, immediately followed by conventional colonoscopy. The diagnostic performance of CT colonography was analyzed relative to lesion size, histological diagnosis, and diagnostic certainty. RESULTS: The sensitivity of CT colonography increased with lesion size (P<0.001), and was 91% (21/23) for lesions > or = 10 mm. All 10 carcinomas and 86% (19/22) of adenomas > or = 5 mm were detected. Unconfirmed or false-positive CT findings were generally small and/or reported with low diagnostic certainty. The specificity of CT colonography would be 45% (30/66; 95% CI 34% to 57%) if patients with findings of any size and any diagnostic certainty were selected for follow-up, and 92% (85/92; 95% CI 85% to 96%) if only patients with CT findings > or = 10 mm classified as certain were selected. CONCLUSION: CT colonography had a high sensitivity for lesions > or = 5 mm. The diagnostic performance increased with lesion size and degree of diagnostic certainty, and was higher for adenomas.