From the RSNA refresher courses - State-of-the-art adrenal imaging

The adrenal gland is a common site of disease, and detection of adrenal mas ses has increased with the expanding use of cross-sectional imaging. Radiol ogy is playing a critical role in not only the detection of adrenal abnorma lities but in characterizing them as benign or malignant. The purpose of th e article is to illustrate and describe the appropriate radiologic work-up for diseases affecting the adrenal gland. The work-up of a suspected hyperf unctioning adrenal mass (pheochromocytoma and aldosteronoma) should start w ith appropriate biochemical screening tests followed by thin-collimation co mputed tomography (CT). If results of CT are not diagnostic, magnetic reson ance (MR) and nuclear medicine imaging examinations should be performed. CT has become the study of choice to differentiate a benign adenoma from a me tastasis in the oncology patient. If the attenuation of the adrenal gland i s over 10 HU at nonenhanced CT, contrast material-enhanced CT should be per formed and washout calculated. Over 50% washout of contrast material on a 1 0-minute delayed CT scan is diagnostic of an adenoma. For adrenal lesions t hat are indeterminate at CT in the oncology patient, chemical shift MR imag ing or adrenal biopsy should be performed. Certain features can be used by the radiologist to establish a definitive diagnosis for most adrenal masses (including carcinoma, infections, and hemorrhage) based on imaging finding s alone.