Detection of flat colorectal polyps at screening CT colonography in comparison with conventional polypoid lesions

BackgroundAlthough the screening of small, flat polyps is clinically important, the role of CT colonography (CTC) screening in their detection has not been thoroughly investigated.PurposeTo evaluate the detection capability and usefulness of CTC in the screening of flat and polypoid lesions by comparing CTC with optic colonoscopy findings as the gold standard.Material and MethodsWe evaluated the CTC detection capability for flat colorectal polyps with a flat surface and a height not exceeding 3 mm (n = 42) by comparing to conventional polypoid lesions (n = 418) according to the polyp diameter. Four types of reconstruction images including multiplanar reconstruction, volume rendering, virtual gross pathology, and virtual endoscopic images were used for visual analysis. We compared the abilities of the four reconstructions for polyp visualization.ResultsDetection sensitivity for flat polyps was 31.3%, 44.4%, and 87.5% for lesions measuring 2–3 mm, 4–5 mm, and ≥6 mm, respectively; the corresponding sensitivi...