title: Adrenal masses: characterization with combined unenhanced and delayed enhanced CT.
abstract: OBJECTIVE
  To assess the accuracy of a dedicated adrenal computed tomographic (CT) protocol.
  
  
  METHODS
  One hundred sixty-six adrenal masses were evaluated with a protocol consisting of unenhanced CT, and, for those with attenuation values greater than 10 HU, contrast material-enhanced and delayed enhanced CT. Attenuation values and enhancement washout calculations were obtained. An adenoma was diagnosed if a mass had an attenuation value of 10 HU or less at unenhanced CT or a percentage enhancement washout value of 60% or higher.
  
  
  RESULTS
  The final diagnosis was adenoma in 127 masses and non-adenoma in 39. Masses measuring more than 10 HU on unenhanced CT scans were confirmed at biopsy (n = 28) or were examined for stability or change in size at follow-up CT performed at a minimum interval of 6 months (n = 33). Thirty-six (92%) of 39 non-adenomas and 124 (98%) of 127 adenomas were correctly characterized. The sensitivity and specificity of this protocol were 98% and 92%, respectively. This protocol correctly characterized 160 (96%) of 166 masses.
  
  
  CONCLUSIONS
  With a combination of unenhanced and delayed enhanced CT, nearly all adrenal masses can be correctly categorized as adenomas or non-adenomas.
authors.affiliation: Department of Radiology, University of Michigan Medical Center, 1500 E Medical Center Dr, Ann Arbor, MI 48109-9723, USA. caoili@umich.edu
authors.forename: Elaine M
authors.initials: EM
authors.lastname: Caoili
authors.forename: Melvyn
authors.initials: M
authors.lastname: Korobkin
authors.forename: Isaac R
authors.initials: IR
authors.lastname: Francis
authors.forename: Richard H
authors.initials: RH
authors.lastname: Cohan
authors.forename: Joel F
authors.initials: JF
authors.lastname: Platt
authors.forename: N Reed
authors.initials: NR
authors.lastname: Dunnick
authors.forename: Kartik I
authors.initials: KI
authors.lastname: Raghupathi
mesh_terms: D000236:Adenoma / Q000000981:diagnostic imaging; D000310:Adrenal Gland Neoplasms / Q000000981:diagnostic imaging*; D000311:Adrenal Glands / Q000000981:diagnostic imaging; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011856:Radiographic Image Enhancement; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed
chemical_list: D003287:Contrast Media