Review: Computed tomographic colonography has high specificity but low-to-moderate sensitivity for detecting colorectal polyps

met the selection criteria. Reference standards included conventional colonoscopy, segmental unblinded colonoscopy (after each colon segment is examined, the results of CTC are revealed to the endoscopist and discrepant segments are reexamined), optimized colonoscopy (in which videotapes of the endoscopy are reviewed and compared with discrepant CTC findings), and surgical findings or results of double-contrast barium enema. Pooled sensitivities and specificities on a per-patient basis were combined and weighted according to sample size. Sensitivity of CT colonography was heterogeneous but increased progressively as polyp size increased (Table). Characteristics of the CTC scanner (e.g., width of collimation, type of detector, and mode of imaging) explained some of the heterogeneity. Specificity was higher than sensitivity and more homogeneous (Table).