Diagnostic performance of CT colonography in a population with high prevalence of large bowel disease.

Background: Although CT colonography (CTC) is a well-known diagnostic modality, it is not yet established as an official screening method mainly due to discrepancies in diagnostic accuracy values reported in the literature. We examined the diagnostic accuracy of CTC in a population with suspicion of large bowel disease.
Material/methods: CTC was performed in 77 patients with 2- and 16-slice CT units after the standard preparation. The results were compared with optical colonoscopy (39%) and/or barium enema (35%) and pathomorphological examinations (44%) and statistically evaluated.
Results: CTC visualized large bowel pathology in 75% of patients. Its diagnostic accuracy vs. optical colonoscopy was significant (C=0.8719, p<0.0001) and higher than that of barium enema (C=0.7774, p<0.0001). CTC was the most accurate in the diagnosis of colorectal carcinoma (C=0.7071). There was statistically significant accuracy between CTC and optical colonoscopy in the evaluation of polyps diameter (C=0.7657), localization (C=0.8913), and morphology (C=0.7568). CTC was the most accurate in depicting large polyps (<10 mm): its sensitivity was 100% and specificity 98%. The diagnostic accuracy of CTC was also statistically significant compared with pathomorphology (C=0.7812, p<0.0001). In 78% of the examined patients, extra-colonic findings were visualized with CTC, 13% of which were clinically important and 22% of which had been occult before.
Conclusions: The diagnostic accuracy of CTC in patients from a population with a high prevalence of large bowel disease was statistically significant. It also enabled the visualization of pathological findings in extra-colonic locations.