Diagnostic accuracy of CT colonography and optical colonoscopy evaluated using surgically resected specimens

The aim of this study was to clarify the diagnostic ability of CT colonography (CTC) using surgically resected specimens to avoid inaccuracy associated with optical colonoscopy (OC).

CTC and OC were performed in 152 consecutive patients with colorectal cancer. Forty patients had simultaneous lesions other than the ones for which the surgery was intended, and these lesions were used as the gold standard. In 24 patients without stenosis, the sensitivity and positive predictive values (PPV) of CTC and OC were evaluated. In 16 patients with stenosis, the diagnostic ability of CTC for lesions located proximal to the stenosis was assessed.

Sensitivity of CTC and OC was 81% and 66% (P = 0.16), and PPV was 90% and 100% (P = 0.13), respectively. For 22 lesions larger than 5 mm, the sensitivity of CTC and OCS was 96% and 91% (P > 0.50), and PPV was 100% and 100%, respectively. In patients with stenosis, sensitivity and PPV were 89% and 80%, respectively. These results were not significantly different from those in patients without stenosis.

CTC is a reliable modality for the diagnosis of colorectal polyps. It is also useful to evaluate the colon proximal to severe stenosis which could not be observed by OC.