title: Computed tomographic histogram analysis in the diagnosis of lipid-poor adenomas: comparison to adrenal washout computed tomography.
abstract: OBJECTIVE
  To evaluate the ability of computed tomographic histogram analysis to diagnose lipid poor adenoma in comparison with adrenal washout computed tomography (CT).
  
  
  METHODS
  Adrenal CT washout examinations performed during a period from January 2000 to July 2005 were reviewed. Computed tomographic histogram analysis was performed on the unenhanced component of the study, and sensitivity was assessed at thresholds of more than 5% and 10% negative pixels. Liver and spleen were used to represent the control/nonadenoma group. Computed tomographic noise was measured recording standard deviation (SD) of mean CT attenuation in adrenal, liver, and spleen.
  
  
  RESULTS
  Twenty-four lipid-poor adenomas included exhibited more than 60% absolute enhancement washout (range, 60%-79%, mean, 69%) and remained stable for a period greater than 6 months. At threshold of more than 5% or 10% negative pixels CT histogram analysis yielded sensitivities of 91.6% and 70.8%, respectively, with 100% specificity. The mean SDs of adrenal, liver, and spleen were 18.2, 16.4 and 15, respectively. These differences in the mean SD were much smaller compared with the differences in the percentage of negative pixels in adrenal, liver, and spleen of 12.75%, 0.75%, and 0.25%, respectively.
  
  
  CONCLUSIONS
  Computed tomographic histogram analysis has good potential in the diagnosis of lipid-poor adenoma and can reduce the need to perform adrenal washout CT.
authors: Department of Medical Imaging, University Health Network and Mount Sinai Hospital, 610 University Avenue, Toronto, Ontario, Canada M5G 2M9. kartik.jhaveri@uhn.on.ca
authors: Kartik S
authors: KS
authors: Jhaveri
authors: Shilpa V
authors: SV
authors: Lad
authors: Masoom A
authors: MA
authors: Haider
mesh_terms: D000236:Adenoma / Q000000981:diagnostic imaging*; D000310:Adrenal Gland Neoplasms / Q000000981:diagnostic imaging*; D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D014057:Tomography, X-Ray Computed / Q000379:methods*