title: CT colonography for synchronous colorectal lesions in patients with colorectal cancer: initial experience.
abstract: OBJECTIVE
  To assess accuracy of CT colonography (CTC) in identifying synchronous lesions in patients with colorectal carcinoma.
  
  
  METHODS
  This study included 174 consecutive patients undergoing CTC as part of staging or primary investigation where a colorectal cancer was diagnosed between 2004 and 2007. Prone unenhanced and portal phase enhanced supine series with air or CO(2) distension were acquired using 4- or 16-slice CT (Toshiba) and read by 2D +/- 3D formats. Synchronous lesions were classified according to American College of Radiology's (ACR) polyp classification. Segmental gold standard was flexible sigmoidoscopy/colonoscopy within 1 year and/or histology of colonic resection supplemented by follow-up. Nine patients without gold standard were excluded. Sensitivity, specificity and accuracy were calculated on a per polyp, per patient and per segment basis and discrepancies analysed.
  
  
  RESULTS
  Direct comparable data were available for 764/990 colonic segments from 165 patients. Of 41 (C2-C4) synchronous lesions on "gold standard", 33 were correctly identified on virtual colonoscopy (VC), overall per polyp sensitivity was 80.5%, with detection rates of 20/24 C3 (83.3%) and 3/3 C4 (100%) with per patient and per segment specificity of 95.4% and 99.2%, respectively.
  
  
  CONCLUSIONS
  CTC is an accurate technique to assess for significant synchronous lesions in patients with colorectal cancer and is applicable for total pre-operative colonic visualisation.
authors.affiliation: Department of Surgery, Heart of England NHS Foundation Trust (Teaching), Bordesley Green East, Birmingham, B9 5SS, UK.
authors.forename: D R
authors.initials: DR
authors.lastname: McArthur
authors.forename: H
authors.initials: H
authors.lastname: Mehrzad
authors.forename: R
authors.initials: R
authors.lastname: Patel
authors.forename: J
authors.initials: J
authors.lastname: Dadds
authors.forename: A
authors.initials: A
authors.lastname: Pallan
authors.forename: S S
authors.initials: SS
authors.lastname: Karandikar
authors.forename: S
authors.initials: S
authors.lastname: Roy-Choudhury
mesh_terms: D000328:Adult; D000368:Aged; D003111:Colonic Polyps / Q000150:complications / Q000000981:diagnostic imaging*; D023881:Colonography, Computed Tomographic / Q000379:methods*; D015179:Colorectal Neoplasms / Q000150:complications* / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity