title: Colorectal polyps: detection with low-dose multi-detector row helical CT colonography versus two sequential colonoscopies.
abstract: OBJECTIVE
  To prospectively evaluate the diagnostic accuracy of low-radiation-dose computed tomographic (CT) colonography for detection of colorectal polyps by using two sequential colonoscopies, with the second colonoscopy as the reference standard.
  
  
  METHODS
  The study was local ethics committee approved, and all patients gave written informed consent. Colonographic images were acquired by using a low-dose multi-detector row CT protocol (effective milliampere-second setting, 10 mAs). Three observers interpreted the CT colonographic data separately and independently by using a two-dimensional technique. Initial conventional colonoscopy was performed by an endoscopist unaware of the CT colonographic findings. Second colonoscopy performed within 2 weeks by a colonoscopist aware of both the CT colonographic and the initial colonoscopic findings served as the reference standard. The sensitivities of CT colonography and initial colonoscopy were calculated on a per-polyp and a per-patient basis. Specificities and positive and negative predictive values also were calculated on a per-patient basis.
  
  
  RESULTS
  Eighty-eight patients underwent CT colonography and initial conventional colonoscopy on the same day. Per-polyp sensitivities were 62% and 83% for CT colonography and initial colonoscopy, respectively. Sensitivities for detection of polyps 6 mm in diameter or larger were 86% and 84% for CT colonography and initial colonoscopy, respectively. Initial colonoscopy failed to depict 16 polyps, six of which were correctly detected with CT colonography. For identification of patients with polyps 6 mm in diameter or larger, CT colonography and initial colonoscopy, respectively, had sensitivities of 84% and 90%, specificities of 82% and 100%, positive predictive values of 70% and 100%, and negative predictive values of 91% and 95%.
  
  
  CONCLUSIONS
  Low-dose CT colonography compares favorably with colonoscopy for detection of colorectal polyps 6 mm in diameter or larger, with markedly decreased performance for detection of polyps 5 mm in diameter or smaller.
authors.affiliation: Department of Radiological Sciences, University of Rome-La Sapienza, Rome, Italy. r_iannaccone@yahoo.it
authors.forename: Riccardo
authors.initials: R
authors.lastname: Iannaccone
authors.forename: Carlo
authors.initials: C
authors.lastname: Catalano
authors.forename: Filippo
authors.initials: F
authors.lastname: Mangiapane
authors.forename: Takamichi
authors.initials: T
authors.lastname: Murakami
authors.forename: Antonietta
authors.initials: A
authors.lastname: Lamazza
authors.forename: Enrico
authors.initials: E
authors.lastname: Fiori
authors.forename: Alberto
authors.initials: A
authors.lastname: Schillaci
authors.forename: Daniele
authors.initials: D
authors.lastname: Marin
authors.forename: Italo
authors.initials: I
authors.lastname: Nofroni
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Hori
authors.forename: Roberto
authors.initials: R
authors.lastname: Passariello
mesh_terms: D000368:Aged; D003111:Colonic Polyps / Q000000981:diagnostic imaging*; D023881:Colonography, Computed Tomographic; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D011829:Radiation Dosage; D012680:Sensitivity and Specificity