CT Colonography with Computer-aided Detection as a Second Reader: Observer Performance Study

doi:10.1148/radiol.2453062161

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Gastrointestinal Imaging

CT Colonography with Computer-aided Detection as a Second Reader: Observer Performance Study¹

Nicholas Petrick, PhD, Maruf Haider, MD, Ronald M. Summers, MD, PhD, Srinath C. Yeshwant, BS, Linda Brown, MD, Edward M. Iuliano, DO, Adeline Louie, MD, J. Richard Choi, MD, ScD, and Perry J. Pickhardt, MD

¹ From the Diagnostic Radiology Department, Clinical Center, National Institutes of Health, Bldg 10, Room 1C351, Bethesda, MD 20892-1182 (M.H., R.M.S., S.C.Y., L.B., A.L.); National Institute of Biomedical Imaging and Bioengineering (NIBIB)/Center for Devices and Radiological Health Joint Laboratory for the Assessment of Medical Imaging Systems, U.S. Food and Drug Administration (FDA), Rockville, Md (N.P.); Department of Radiology, Georgetown University School of Medicine, Washington, DC (E.M.I.); Department of Radiology, Walter Reed Army Medical Center, Washington, DC (J.R.C.); and Department of Radiology, University of Wisconsin Medical School, Madison, Wis (P.J.P.). From the 2005 RSNA Annual Meeting. Received December 19, 2006; revision requested February 16, 2007; revision received April 4; final version accepted May 4. Supported in part by the intramural research program of the National Institutes of Health Clinical Center (NIBIB). No FDA endorsement of any product or company mentioned in this manuscript should be inferred. Address correspondence to R.M.S. (e-mail: rms{at}nih.gov).

Purpose: To evaluate the effect of computer-aided detection (CAD)as second reader on radiologists' diagnostic performance in interpretingcomputed tomographic (CT) colonographic examinations by using a primarytwo-dimensional (2D) approach, with segmental, unblinded opticalcolonoscopy as the reference standard.

Materials and Methods: This HIPAA-compliant study was IRB-approvedwith written informed consent. Four board-certified radiologistsanalyzed 60 CT examinations with a commercially available reviewsystem. Two-dimensional transverse views were used for initial polypdetection, while three-dimensional (3D) endoluminal and 2D multiplanarviews were available for problem solving. After initial review withoutCAD, the reader was shown CAD-identified polyp candidates. The readerswere then allowed to add to or modify their original diagnoses. Polyplocation, CT Colonography Reporting and Data System categorization,and reader confidence as to the likelihood of a candidate being apolyp were recorded before and after CAD reading. The area underthe receiver operating characteristic (ROC) curve (AUC), sensitivity,and specificity were estimated for CT examinations with and withoutCAD readings by using multireader multicase analysis.

Results: Use of CAD led to nonsignificant average reader AUC increasesof 0.03, 0.03, and 0.04 for patients with adenomatous polyps 6 mmor larger, 6–9 mm, and 10 mm or larger, respectively (P $≥$ .25);likewise, CAD increased average reader sensitivity by 0.15, 0.16,and 0.14 for those respective groups, with a corresponding decreasein specificity of 0.14. These changes achieved significance for the6 mm or larger group (P < .01), 6–9 mm group (P < .02),and for specificity (P < .01), but not for the 10 mm or largergroup (P > .16). The average reading time was 5.1 minutes ±3.4 (standard deviation) without CAD. CAD added an average of 3.1minutes ± 4.3 (62%) to each reading (supine and prone positionscombined); average total reading time, 8.2 minutes ± 5.8.