Diagnostic performance of computed tomography colonography and colonoscopy: a prospective and validated analysis of 231 paired examinations

Detection of colorectal tumors with computed tomography colonography (CTC) is an alternative to conventional colonoscopy (CC), and clarification of the diagnostic performance is essential for cost-effective use of both technologies.

To evaluate the diagnostic performance of CTC compared with CC.

231 consecutive CTCs were performed prior to same-day scheduled CC. The radiologist and endoscopists were blinded to each other's findings. Patients underwent a polyethylene glycol bowel preparation, and were scanned in prone and supine positions using a single-detector helical CT scanner and commercially available software for image analysis. Findings were validated (matched) in an unblinded comparison with video-recordings of the CCs and re-CCs in cases of doubt.

For patients with polyps >/=5 mm and >/=10 mm, the sensitivity was 69% (95% CI 58-80%) and 81% (68-94%), and the specificity was 91% (84-98%) and 98% (93-100%), respectively. For detection of polyps >/=5 mm and >/=10 mm, the sensitivity was 66% (57-75%) and 77% (65-89%). A flat, elevated low-grade carcinoma was missed by CTC. One cancer relapse was missed by CC, and a cecal cancer was missed by an incomplete CC and follow-up double-contrast barium enema.

CC was superior to CTC and should remain first choice for the diagnosis of colorectal polyps. However, for diagnosis of lesions >/=10 mm, CTC and CC should be considered as complementary methods.