CT colonography effectively identifies carpet lesions

CT colonography has been found to effectively depict carpet lesions, according to a study published in the February issue of Radiology.

The study also revealed that common carpet lesion features include older patient age, rectal or cecal location, surface coating with oral contrast material, multiple computer-aided detection (CAD) hits, advanced but benign histologic features, and surgical treatment.

Controversy surrounds the clinical importance of nonpolypoid colorectal lesions. While carpet lesions, a subset of nonpolypoid colorectal lesions, have demonstrated clinical relevance, information regarding their detection at CT colonography remains limited. Lead author Perry J. Pickhardt, MD, of the University of Wisconsin in Madison, and colleagues aimed to describe the clinical, imaging, and pathologic features of carpet lesions at CT colonography.

Imaging reports for 9,152 adults undergoing initial CT colongraphy were included in the study for retrospective review. Those with neoplastic carpet lesions were analyzed for maximal lesion width and height, oral contrast material coating, segmental location, and CAD findings. The researchers identified 18 carpet lesions in 18 patients, which were then confirmed at colonoscopy and pathologic examination. The overall prevalence of carpet lesions in the study population was 0.2 percent.

The average lesion width was 46.5 millimeters, while the average height was 7.9 millimeters. Pickhardt et al noticed surface retention of oral contrast material in all cases. Sixteen of the lesions were found in the distal rectosigmoid or proximal right colon. CAD detected 17, or 94.4 percent, of the carpet lesions. Sixteen of the lesions exhibited advanced histologic features and sixteen needed surgical treatment for complete excision.

Despite lack of formal assessment of population prevalence and accuracy, Pickhardt and colleagues wrote, “Our experience with carpet lesions at CT colonography could help raise awareness of the imaging manifestations of these uncommon but important lesions.”