title: Delayed enhanced CT for differentiation of benign from malignant adrenal masses.
abstract: OBJECTIVE
  To determine whether adenomas can be differentiated from nonadenomas on 1-hour-delayed enhanced computed tomographic (CT) scans.
  
  
  METHODS
  In a prospective evaluation of 51 adrenal masses in 39 patients, the CT attenuation was measured at the time of contrast enhancement and 1 hour later. The results were compared for adenomas (n = 41) and metastases (n = 10).
  
  
  RESULTS
  On 1-hour-delayed enhanced CT scans, the mean attenuation of the adenomas was 11 HU +/- 13 versus 49 HU +/- 8.3 for metastases (P < .001). At a threshold value of 30 HU, specificity and positive predictive value for the diagnosis of adenoma were 100% with a sensitivity of 95%. The mean decrease in attenuation during the 1-hour delay was 74% +/- 37 for the adenomas versus 31% +/- 28 for the metastases (P < .001).
  
  
  CONCLUSIONS
  CT densitometry on delayed scans obtained 1 hour after contrast enhancement may be useful in characterizing an adrenal mass as an adenoma. When CT is performed with a 150-mL bolus injection of contrast material and with the scanning parameters described in this study, other procedures or imaging studies may be unnecessary if the mass measures less than 30 HU on the delayed scans.
authors: Department of Radiology, University of Michigan Hospitals, Ann Arbor 48109-0030, USA.
authors: M
authors: M
authors: Korobkin
authors: F J
authors: FJ
authors: Brodeur
authors: I R
authors: IR
authors: Francis
authors: L E
authors: LE
authors: Quint
authors: N R
authors: NR
authors: Dunnick
authors: M
authors: M
authors: Goodsitt
mesh_terms: D000230:Adenocarcinoma / Q000000981:diagnostic imaging* / Q000556:secondary; D000236:Adenoma / Q000000981:diagnostic imaging*; D000310:Adrenal Gland Neoplasms / Q000000981:diagnostic imaging* / Q000556:secondary; D000311:Adrenal Glands / Q000000981:diagnostic imaging; D000328:Adult; D000368:Aged; D003287:Contrast Media; D003937:Diagnosis, Differential; D003973:Diatrizoate; D005260:Female; D006801:Humans; D007472:Iohexol; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012372:ROC Curve; D012680:Sensitivity and Specificity; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods* / Q000706:statistics & numerical data
chemical_list: D003287:Contrast Media; D003973:Diatrizoate; D007472:Iohexol