Sensitivity of CT Colonography for Nonpolypoid Colorectal Lesions Interpreted by Human Readers and With Computer-Aided Detection

Abstract

The purpose of our study was to determine the sensitivity of CT colonography (CTC) interpreted by human readers and with computer-aided detection (CAD) for genuinely nonpolypoid colorectal lesions, defined as 2 mm or less in lesion height at colonoscopy. A computerized database search for a 33-month period found 21 patients who had undergone both colonoscopy and CTC and who had a total of 23 genuinely nonpolypoid colorectal lesions: eight adenomas (9-30 mm in width), 10 stage Tis or T1 adenocarcinomas (10-25 mm), and five nonadenomatous lesions (8-20 mm). CTC was performed using a cathartic preparation and fecal tagging and was interpreted by experienced readers in a blinded manner using a primary 3D method and with CAD. The sensitivities of human readers for nonpolypoid adenomatous lesions (i.e., both adenomas and adenocarcinomas), adenocarcinomas, and nonadenomatous lesions were 66.7% (12/18), 90% (9/10), and 0% (0/5), respectively. Sensitivities were 55.6% (10/18), 90% (9/10), and 0% (0/5) for CAD. A 10-mm stage T1 adenocarcinoma was missed by a human reader on blinded review but was detected with CAD. Both human readers and CAD yielded significantly higher sensitivity for adenomatous lesions than for nonadenomatous lesions (p = 0.014 and 0.046, respectively) and for adenocarcinomas than for noncancerous lesions (p = 0.003 and 0.0001, respectively). CTC showed a high sensitivity for nonpolypoid stage Tis and T1 adenocarcinomas 10 mm or greater in width despite the limited overall sensitivity for nonpolypoid adenomatous lesions, when performed using cathartic preparation and fecal tagging.