title: CT sensitivity for adrenal adenoma according to lesion size.
abstract: OBJECTIVE
  To retrospectively evaluate CT sensitivity for characterizing adrenal adenoma according to lesion size.
  
  
  METHODS
  Between January 2004 and November 2012, 140 patients with 140 histologically proven adenomas underwent preoperative adrenal CT protocols consisting of unenhanced CT, early enhanced CT, and delayed enhanced CT. Adenomas were divided into three size groups: small adenoma (n = 60), ≥ 1 to <2 cm; medium adenoma (n = 47), ≥ 2 to <3 cm; and large adenoma (n = 33), ≥ 3 cm. Adenoma was diagnosed when a lesion met one of the following criteria: (a) unenhanced CT attenuation value ≤ 10 HU, (b) absolute percentage washout ≥ 60%, or (c) relative percentage washout ≥ 40%. The standard reference was pathologic examination of an adrenalectomy specimen. Adenoma size, lesion attenuation value, or percentage washout was correlated with the Spearman's rank correlation. CT sensitivities were compared between size groups of adenomas with the Fisher's exact test.
  
  
  RESULTS
  As adenoma size increased, the lesion attenuation value (ρ = 0.324; P = 0.001) increased on unenhanced CT, and the absolute (ρ = -0.186; P = 0.028) or relative (ρ = -0.374; P < 0.001) percentage washout decreased on early and delayed enhanced CT. CT sensitivities were 100% (60/60) for small adenomas, 97.9% (46/47) for medium adenomas, and 66.7% (22/33) for large adenomas (P < 0.001).
  
  
  CONCLUSIONS
  Adrenal CT protocols misdiagnose a substantial number of large adenomas as non-adenomas because CT sensitivity for adenoma markedly decreases, when the lesion size is 3 cm or larger.
authors.affiliation: The Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Ilwon-dong, Kangnam-ku, Seoul, 135-710, Korea.|The Department of Radiology, Research Institute of Radiological Science, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Sung Yoon
authors.initials: SY
authors.lastname: Park
authors.affiliation: The Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Ilwon-dong, Kangnam-ku, Seoul, 135-710, Korea. rapark@skku.edu.
authors.forename: Byung Kwan
authors.initials: BK
authors.lastname: Park
authors.affiliation: The Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Ilwon-dong, Kangnam-ku, Seoul, 135-710, Korea.
authors.forename: Jung Jae
authors.initials: JJ
authors.lastname: Park
authors.affiliation: The Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Ilwon-dong, Kangnam-ku, Seoul, 135-710, Korea.
authors.forename: Chan Kyo
authors.initials: CK
authors.lastname: Kim
mesh_terms: D000236:Adenoma / Q000000981:diagnostic imaging*; D000310:Adrenal Gland Neoplasms / Q000000981:diagnostic imaging*; D000311:Adrenal Glands / Q000000981:diagnostic imaging; D000328:Adult; D000368:Aged; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed; D055815:Young Adult
keywords: Adenoma size; Adrenal adenoma; Computed tomography; Sensitivity