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RSNA 2005 > CT Virtual Colonoscopy Computer-aided Polyp Detection ...

  CODE: SSG10-05
  SESSION: Gastrointestinal (CT Colonography: Computer-aided Diagnosis)
  CT Virtual Colonoscopy Computer-aided Polyp Detection in a Screening Population

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Ronald Summers MD, PhD
Abstract Co-Author
Jack Yao PhD
Perry Pickhardt MD
Marek Franaszek PhD
Ingmar Bitter PhD
Jong-Ho Choi MD
et al
- Author stated no financial disclosure

- Disclosure information unavailable
  DATE: Tuesday, November 29 2005
  START TIME: 11:10 AM
  END TIME: 11:20 AM

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

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