title: CT colonography for the detection of nonpolypoid adenomas: sensitivity assessed with restricted national CT colonography trial criteria.
abstract: OBJECTIVE
  The purpose of this study was to determine the prevalence of nonpolypoid adenomas and the sensitivity of CT colonography (CTC) in their detection by use of the restricted criteria of height-to-width ratio<50% and height elevation≤3 mm.
  
  
  METHODS
  In the National CT Colonography Trial (American College of Radiology Imaging Network protocol 6664), a cohort of 2531 participants without symptoms underwent CTC and screening colonoscopy. The CTC examinations were interpreted with both 2D and 3D techniques. Nonpolypoid adenomatous polyps identified with CTC or colonoscopy were retrospectively reviewed to determine which polyps met the restricted criteria. The prevalence of nonpolypoid adenomas and the prospective sensitivity of CTC were determined. Descriptive statistics were used to report the prevalence, size, and histologic features. The sensitivities (with 95% CIs) for nonpolypoid and polypoid lesions were compared by two-sided Z test for independent binomial proportions.
  
  
  RESULTS
  The retrospective review confirmed 21 nonpolypoid adenomas, yielding a prevalence of 0.83% (21 of 2531 participants). Eight (38.1%) were advanced adenomas, many (50% [4/8]) only because of large size (≥10 mm). The overall per polyp sensitivity of CTC (combined 2D and 3D interpretation) for detecting nonpolypoid adenomas≥5 mm (n=21) was 0.76; ≥6 mm (n=16), 0.75; and ≥10 mm (n=5), 0.80. These values were not statistically different from the sensitivity of detecting polypoid adenomas (p>0.37).
  
  
  CONCLUSIONS
  In this large screening population, nonpolypoid adenomas had a very low prevalence (<1%), and advanced pathologic features were uncommon in polyps<10 mm in diameter. Most nonpolypoid adenomas are technically visible at CTC. The prospective sensitivity is similar to that for polypoid adenomas when the interpretation combines both 2D and 3D review.
authors.affiliation: 1 Department of Radiology, Mayo Clinic, 200 First St SW, Rochester, MN 55905.
authors.forename: Jeff L
authors.initials: JL
authors.lastname: Fidler
authors.forename: Zheng
authors.initials: Z
authors.lastname: Zhang
authors.forename: Benjamin A
authors.initials: BA
authors.lastname: Herman
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Limburg
authors.forename: J G
authors.initials: JG
authors.lastname: Fletcher
authors.forename: Abraham
authors.initials: A
authors.lastname: Dachman
authors.forename: Jay P
authors.initials: JP
authors.lastname: Heiken
authors.forename: Mark D
authors.initials: MD
authors.lastname: Kuo
authors.forename: Christine O
authors.initials: CO
authors.lastname: Menias
authors.forename: Bettina
authors.initials: B
authors.lastname: Siewert
authors.forename: Jugesh I
authors.initials: JI
authors.lastname: Cheema
authors.forename: Richard G
authors.initials: RG
authors.lastname: Obregon
authors.forename: Peter
authors.initials: P
authors.lastname: Zimmerman
authors.forename: Karen M
authors.initials: KM
authors.lastname: Horton
authors.forename: Kevin
authors.initials: K
authors.lastname: Coakley
authors.forename: Revathy B
authors.initials: RB
authors.lastname: Iyer
authors.forename: Amy
authors.initials: A
authors.lastname: Hara
authors.forename: Robert A
authors.initials: RA
authors.lastname: Halvorsen
authors.forename: Giovanna
authors.initials: G
authors.lastname: Casola
authors.forename: Judy
authors.initials: J
authors.lastname: Yee
authors.forename: Lawrence J
authors.initials: LJ
authors.lastname: Burgart
authors.forename: C Daniel
authors.initials: CD
authors.lastname: Johnson
mesh_terms: D000236:Adenoma / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D000368:Aged; D000369:Aged, 80 and over; D003110:Colonic Neoplasms / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D003111:Colonic Polyps / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D023881:Colonography, Computed Tomographic / Q000379:methods / Q000592:standards*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017410:Practice Guidelines as Topic; D015995:Prevalence; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014481:United States / Q000453:epidemiology
keywords: CT colonography; colon cancer; nonpolypoid adenoma