[Radiology of the adrenal glands]

An important principle of diagnostic imaging of the adrenal glands is to characterize an adrenal mass as an adenoma using computed tomography (CT) or magnetic resonance imaging (MRI) techniques. Most techniques exploit the fact that typical adrenal adenomas are lipid-rich so that lipid-poor adenomas, however, remain a diagnostic problem. A CT attenuation ≤ 10 HU, more than 10% negative pixels as demonstrated by histogram analysis, an absolute washout of more than 60%, a relative washout of more than 40% and a signal drop of more than 20% in opposed-phase images are characteristic for adrenal adenomas. Endocrine dysfunction is diagnosed biochemically and not by means of imaging but are necessary to localize a functioning tumor. An important principle is to combine anatomical with functional imaging studies. Percutaneous biopsy of adrenal glands is only indicated when an adrenal mass is the only potential metastasis of a diagnosed primary tumor.