Adrenal lesion characterization by washout on a three-phase CT

Characterization of adrenal masses that are less than 3cm in diameter can be achieved by calculating its washout on a three-phase CT acquisition (unenhanced, venous, and delayed phase). It does not apply to masses that have a specific appearance such as myelolipoma (fat attenuation). Lesions with attenuation ≤10HU on unenhanced scan are lipid-rich adenomas.


  • Unenhanced
  • 150 ml iodine c.m. i.v. 2 ml/s
  • Venous phase at 60 s
  • Delayed scan at 15 min
  • ROI min. 1/2 size of the lesion
Parameter Value  
Unenhanced attenuation HU
Venous phase attenuation * HU
Delayed phase attenuation * HU
* Required fields


1. Blake MA, Kalra MK, Sweeney AT, Lucey BC, et al. Distinguishing benign from malignant adrenal masses: multi-detector row CT protocol with 10-minute delay. Radiology. 2006;238:578-585.