title: Computerized detection of colonic polyps at CT colonography on the basis of volumetric features: pilot study.
abstract: OBJECTIVE
  To develop a computer-aided diagnosis (CAD) scheme for automated detection of colonic polyps on the basis of volumetric features and to assess its accuracy on the basis of colonoscopy, the standard.
  
  
  METHODS
  Computed tomographic (CT) colonography was performed in patients with use of standard bowel cleansing, air insufflation, and helical scanning in supine and prone positions. The colon was extracted from volumetric data sets generated from transverse CT sections. Volumetric features characterizing polyps were computed at each point in the extracted colon. Polyps were detected by means of hysteresis thresholding and fuzzy clustering followed by a rule-based test on the basis of feature values. Locations of the detected polyps were compared with those detected at conventional colonoscopy.
  
  
  RESULTS
  Forty-one cases were analyzed: nine cases with polyps and 32 without polyps. Each case with polyps had one polyp of clinically important size (six were 5-9 mm; three, 10 mm). Thus, there were 82 volumetric data sets, 18 included polyps. Eighty-nine percent (16 of 18) of the polyps were detected. Each of the two false-negative findings was detected in the other position; thus, 100% of polyp cases were detected, with 2.5 false-positive findings per patient. The false-positive findings were similar to those due to common perceptual errors. Most of the false-positive findings were easily distinguishable from true polyps by experienced radiologists.
  
  
  CONCLUSIONS
  The CAD scheme has the potential to depict polyps with high sensitivity and an acceptable false-positive rate.
authors.affiliation: Department of Radiology, University of Chicago, Chicago, IL 60637, USA. yoshida@uchicago.edu
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Yoshida
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Masutani
authors.forename: Peter
authors.initials: P
authors.lastname: MacEneaney
authors.forename: David T
authors.initials: DT
authors.lastname: Rubin
authors.forename: Abraham H
authors.initials: AH
authors.lastname: Dachman
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003111:Colonic Polyps / Q000000981:diagnostic imaging* / Q000473:pathology*; D023881:Colonography, Computed Tomographic; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D015203:Reproducibility of Results