title: CT colonography: multiobserver diagnostic performance.
abstract: OBJECTIVE
  To prospectively evaluate multiobserver diagnostic performance and reader agreement for colorectal polyp detection in a well-characterized cohort of patients with increased number of polyps, compared with an average-risk patient, with colonoscopy as the reference standard.
  
  
  METHODS
  A cohort of 70 patients suspected of having polyps was examined with spiral computed tomographic (CT) colonography, with colonoscopy performed the same day. After air insufflation per rectum, supine and prone images were obtained with single-detector row CT (5-mm collimation, 8-mm table increment, 2-mm reconstruction interval). Images were analyzed independently by four experienced abdominal radiologists using two-dimensional multiplanar reformation followed by selective use of three-dimensional endoscopic volume-rendered images. Data were analyzed both per polyp and per patient.
  
  
  RESULTS
  Analysis per polyp demonstrated a pooled sensitivity of 0.68 for lesions 10 mm or larger (n = 40), with 75% agreement among the four readers. Analysis per patient demonstrated improved detection and agreement, with a pooled sensitivity of 0.88 for patients with polyps or cancers 10 mm or larger (n = 28), with 94% agreement. When sensitivity and receiver operating characteristic analyses were analyzed per polyp size threshold, results among readers converged and peaked at polyp diameters of approximately 10 mm.
  
  
  CONCLUSIONS
  In this patient cohort, diagnostic performance and interobserver agreement with single-detector row CT colonography was sufficient for detection of patients with lesions 10 mm or larger, with more variable results for smaller polyps.
authors.affiliation: Mallinckrodt Institute of Radiology, Washington University School of Medicine, 510 S Kingshighway Blvd, St Louis, MO 63110, USA. mcfarlandb@mir.wustl.edu
authors.forename: Elizabeth G
authors.initials: EG
authors.lastname: McFarland
authors.forename: Thomas K
authors.initials: TK
authors.lastname: Pilgram
authors.forename: James A
authors.initials: JA
authors.lastname: Brink
authors.forename: Ronan A
authors.initials: RA
authors.lastname: McDermott
authors.forename: Cynthia V
authors.initials: CV
authors.lastname: Santillan
authors.forename: Patrick W
authors.initials: PW
authors.lastname: Brady
authors.forename: Jay P
authors.initials: JP
authors.lastname: Heiken
authors.forename: Dennis M
authors.initials: DM
authors.lastname: Balfe
authors.forename: Leonard B
authors.initials: LB
authors.lastname: Weinstock
authors.forename: Erik P
authors.initials: EP
authors.lastname: Thyssen
authors.forename: Benjamin
authors.initials: B
authors.lastname: Littenberg
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D003111:Colonic Polyps / Q000000981:diagnostic imaging*; D023881:Colonography, Computed Tomographic / Q000706:statistics & numerical data*; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity