Ronald M. Summers MD, PhD, Presenter: Nothing to Disclose

Jack Yao PhD, Abstract Co-Author: Nothing to Disclose

Perry Joseph Pickhardt MD, Abstract Co-Author: Nothing to Disclose

Marek Franaszek PhD, Abstract Co-Author: Nothing to Disclose

Ingmar Bitter PhD, Abstract Co-Author: Nothing to Disclose

Jong-Ho Richard Choi MD, Abstract Co-Author: Nothing to Disclose

Daniel Brickman BS, Abstract Co-Author: Nothing to Disclose

Vamsi Krishna BS, Abstract Co-Author: Nothing to Disclose

et al, Abstract Co-Author: Nothing to Disclose

To determine whether a computer-aided detection (CAD) program can detect adenomatous colonic polyps on CT virtual colonoscopy of patients in a screening population.

The data set was a cohort of 1,186 screening patients at three medical centers. All patients underwent same day virtual and optical colonoscopy. Our enhanced gold standard combined segmental unblinded optical colonoscopy and retrospective identification of polyp coordinates. The data were divided into separate training (n=394) and test (n=792) sets for analysis by CAD. Sensitivities, false positive rates and free-response receiver operating characteristic (FROC) curves were computed for adenomatous polyp size thresholds of 8 mm and 10 mm.

For the test set, CAD’s per polyp and per patient sensitivities were 86.2% (25/29, 95% CI [68.3%, 96.1%]) and 89.3% (25/28, [71.8%, 97.7%]), respectively, for detecting adenomatous polyps at least 1 cm in size. The false-positive rate was 2.1 [2.0, 2.2] false polyps per patient. Both carcinomas were detected by CAD at a false positive rate of 0.7 per patient; only one of two was detected by optical colonoscopy prior to segmental unblinding. The per patient sensitivity of CAD for adenomas 8 mm or larger in the test set, 85.4% (41/48, [72.2%, 93.9%]), was comparable to that of optical colonoscopy prior to segmental unblinding, 89.6% (43/48, [77.3, 96.5]). For adenomas 8 mm or larger, the false-positive rate was 6.7 [6.5, 6.9] false polyps per patient. The most common causes of CAD false-positives were ileocecal valves and colonic folds. False-negatives were most commonly on the air-fluid boundary or on or adjacent to normal colonic folds. FROC analysis showed that sensitivities were slightly higher (< 5%) on the training set compared to the test set for both the 8 mm and 10 mm size thresholds.

The sensitivity and false-positive rate of computer-aided adenomatous polyp detection in an asymptomatic screening population were in the range likely to be clinically acceptable at both 8 mm and 10 mm size thresholds and were generalizable to fresh CT virtual colonoscopy data.

P.J.P.: On medical advisory boards of Viatronix, Inc. and Medicsight, IncJ.R.C.: On the medical advisory board of Viatronix, IncR.M.S.,J.Y.,M.F.,P.J.P.: Patents pending and/or awarded in the subject area of this abstract.

Summers, R, Yao, J, Pickhardt, P, Franaszek, M, Bitter, I, Choi, J, Brickman, D, Krishna, V, et al, , CT Virtual Colonoscopy Computer-aided Polyp Detection in a Screening Population.  Radiological Society of North America 2005 Scientific Assembly and Annual Meeting, November 27 - December 2, 2005 ,Chicago IL. http://archive.rsna.org/2005/4406978.html