Non-invasive evaluation of the incidentally detected indeterminate adrenal mass

Clinically silent adrenal masses are discovered incidentally during diagnostic testing or treatment for clinical conditions that are not related to suspicion of adrenal disease; thus, they are commonly referred to as ‘incidentalomas’. The widespread use of high-resolution anatomic imaging techniques such as computed tomography (CT) and magnetic resonance (MR) imaging has led to the increased detection of these masses. In many patients without a known extra-adrenal primary malignancy—and even in patients with a primary neoplasm—most adrenal masses ultimately prove to be benign. However, it remains important that these adrenal masses are accurately characterized to exclude the treatable causes of adrenal disease, and also to accurately stage the oncology patient. The purpose of this chapter is to describe the findings and recent advances in non-invasive imaging methods that are now available for the accurate characterization of incidentally detected adrenal masses (i.e. the differentiation of benign from malignant masses). The imaging techniques and the algorithms that are used in our institution for the evaluation of incidentally detected adrenal mass will be described.