Spiral CT colonography: Reader agreement and diagnostic performance with two- and three-dimensional image-display techniques

PURPOSE: To assess the diagnostic performance and reader agreement with two -dimensional (2D) and three-dimensional (3D) display techniques for detecti ng colorectal polyps with spiral computed tomographic (CT) colonography. MATERIALS AND METHODS: A test set of 30 colonic segments was developed from spiral CT colonographic studies (12 with polyps and 18 without). The 12 se gments with polyps contained 22 lesions (11 polyps <10 mm, 11 polyps or can cers <greater than or equal to>10 mm), with all findings verified with colo noscopy. Three specific 2D and 30 image-display techniques were tested. Thr ee experienced abdominal radiologists independently analyzed each test case and were retested 6 weeks later. RESULTS: The results of readings 1 and 2 were similar for all image-display techniques among the readers. Pooled segment results were sensitivity of 8 9%-92% and specificity of 72%-83%. Pooled polyp size results for sensitivit y and positive predictive value were 77%-86% and 74%-86% tall polyps, n = 2 2), 91%-100% and 85%-100% (polyps or cancers > 10 mm, n = 11), and 61%-73% and 61%-80% (polyps 5-9 mm, n = 11), respectively. Overall intraobserver ag reement was good for the three display techniques (kappa, 0.60-1.00); howev er, interobserver agreement for 2D multiplanar reformation was lower (kappa , 0.53-0.80). CONCLUSION: Among experienced abdominal radiologists, similar diagnostic pe rformance in polyp detection was found among 2D multiplanar reformation and 3D display techniques, although individual cases showed improved character ization with 3D display techniques. Evaluation of reader agreement demonstr ated good intraobserver agreement, with variable interobserver agreement.