CT Colonography: Investigation of the Optimum Reader Paradigm by Using Computer-aided Detection Software

doi:10.1148/radiol.2461070190

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Gastrointestinal Imaging

CT Colonography: Investigation of the Optimum Reader Paradigm by Using Computer-aided Detection Software¹

Stuart A. Taylor, MD, MRCP, FRCR, Susan C. Charman, MSc, Philippe Lefere, MD, Elizabeth G. McFarland, MD, Erik K. Paulson, MD, Judy Yee, MD, Rizwan Aslam, MD, John M. Barlow, MD, Arun Gupta, MRCP, FRCR, David H. Kim, MD, Chad M. Miller, MD, and Steve Halligan, MD, MRCP, FRCR

¹ From the Department of Specialist X-Ray (S.A.T., S.H.) and Medical Statistics Unit (S.C.C.), University College Hospital, 235 Euston Rd, 2F Podium, London NW1 2BU, England; Department of Radiology, Stedelijk Ziekenhuis, Roeselare, Belgium (P.L.); Department of Radiology, Mallinckrodt Institute of Radiology, St Louis, Mo (E.G.M.); Abdominal Imaging Section, Duke University Medical Center, Durham, NC (E.K.P., C.M.M.); Department of Radiology, San Francisco VA Medical Center, University of California, San Francisco, Calif (J.Y., R.A.); Department of Radiology, Mayo Clinic College of Medicine, Rochester, Minn (J.M.B.); Department of Intestinal Imaging, St Mark's Hospital, Harrow, United Kingdom (A.G.); and Department of Radiology, University of Wisconsin Medical School, Madison, Wis (D.H.K.). From the 2006 RSNA Annual Meeting. Received January 29, 2007; revision requested March 27; revision received May 9; final version accepted June 11. This work was supported in part by the U.K. Department of Health's NIHR Biomedical Research Centres. Address correspondence to S.A.T. (e-mail: csytaylor{at}yahoo.co.uk).

Purpose: To prospectively compare the diagnostic performance andtime efficiency of both second and concurrent computer-aided detection(CAD) reading paradigms for retrospectively obtained computed tomographic(CT) colonography data sets by using consensus reading (three radiologists)of colonoscopic findings as a reference standard.

Materials and Methods: Ethical permission, HIPAA compliance (forU.S. institutions), and patient consent were obtained from all institutionsfor use of CT colonography data sets in this study. Ten radiologistseach read 25 CT colonography data sets (12 men, 13 women; mean age,61 years) containing 69 polyps (28 were 1–5 mm, 41 were $≥$ 6 mm)by using workstations integrated with CAD software. Reading was randomizedto either "second read" CAD (applied only after initial unassistedassessment) or "concurrent read" CAD (applied at the start of assessment).Data sets were reread 6 weeks later by using the opposing paradigm.Polyp sensitivity and reading times were compared by using multilevellogistic and linear regression, respectively. Receiver operatingcharacteristic (ROC) curves were generated.

Results: Compared with the unassisted read, odds of improved polyp( $≥$ 6 mm) detection were 1.5 (95% confidence interval [CI]: 1.0, 2.2)and 1.3 (95% CI: 0.9, 1.9) by using CAD as second and concurrentreader, respectively. Detection odds by using CAD concurrently were0.87 (95% CI: 0.59, 1.3) and 0.76 (95% CI: 0.57, 1.01) those of secondread CAD, excluding and including polyps 1–5 mm, respectively.The concurrent read took 2.9 minutes (95% CI: –3.8, –1.9)less than did second read. The mean areas under the ROC curve (95%CI) for the unassisted read, second read CAD, and concurrent readCAD were 0.83 (95% CI: 0.78, 0.87), 0.86 (95% CI: 0.82, 0.90), and0.88 (95% CI: 0.83, 0.92), respectively.