Computed tomography evaluation of adrenal masses

Computed tomography is the first line modality in the evaluation of patients with adrenal gland masses, and has the potential to be very accurate in the localization of adrenal gland masses in patients with diseases associated with hyperfunctioning conditions of the adrenal gland. Computed tomography allows a specific diagnosis of acute adrenal haemorrhage, adrenal myelolipoma, and adrenal cysts. It is also helpful in the assessment of patients with Addison's disease, particularly the subacute form secondary to granulomatous diseases. Quantitative evaluation of adrenal masses on unenhanced or delayed-enhanced computed tomography has been shown to be highly accurate in distinguishing adrenal adenomas from non-adenomas. Attenuation of 18 HU or less on unenhanced computed tomography scans indicates adenoma with a high specificity and acceptable sensitivity. On delayed-enhanced computed tomography scans, adrenal adenomas exhibit a greater washout of contrast material than do adrenal non-adenomas. Therefore, adrenal non-adenomas have significantly higher attenuation than adenomas on delayed-enhanced computed tomography scans obtained at arbitrarily chosen times (3-60 min) after the initiation of contrast material administration.