Adrenal Masses

Abstract

Adrenal masses are among the most common incidentally discovered lesions on cross-sectional imaging with estimated incidence of approximately 5%. In addition, adrenal lesions can also be detected as part of an endocrinology workup with suspicion of a functional adrenal mass. Regardless of the source of detection, it is crucial to differentiate a benign from a malignant process and furthermore utilize characteristic imaging appearance of different adrenal masses to facilitate diagnosis and guide management. There are numerous imaging protocols and postprocessing methods for evaluation of adrenal masses with high sensitivity and specificity with small differences between institutions. Currently, the most widely used imaging modality for evaluation of adrenal mass is computed tomography without and with contrast washout assessment. In this article, we review diagnostic approaches to adrenal masses using computed tomography and magnetic resonance imaging techniques and present imaging strategies utilized at our institution. The advantages and challenges of these imaging modalities for evaluation of adrenal pathologies are discussed.

Técnicas de imagem na caracterização de lesões adrenais

“…Extensive lesions may cause symptoms, while smaller lesions are in general incidentally identified or found during staging procedures in cancer patients. In both situations, the characterization of the lesion is strongly based on imaging diagnosis techniques (2,4,5) .…”

“…However, up to one third of all adenomas have a reduced amount of intracellular fat, and thus present attenuation values higher than 10 HU at non-contrast enhanced CT, like almost all malignant lesions (2,5,11) . At MRI, the presence of intracellular fat may be detected by means of the chemical shift technique (12) .…”

“…At MRI, the presence of intracellular fat may be detected by means of the chemical shift technique (12) . There is no significant difference between CT and MRI techniques for characterizing lipid-rich adenomas, but MRI may be superior in the evaluation of lipid-poor adenomas which present higher attenuation values (up to 30 HU) at CT (2,5,11) .…”

“…With the value of attenuation at non-contrast enhanced CT, the absolute washout percentage (AWP) may also be calculated. Many studies have demonstrated that both calculations (RWP and AWP) allow for a highly accurate characterization of adrenal lesions, so such measurements are routinely utilized (5,6,15) .…”

“…Different investigation algorithms described in the literature seek to organize the utilization of such tools (2,3,5,18) . Continuous developments in MRI apparatuses have led to the inclusion of spectroscopy as a promising technique to be incorporated into the future investigation guidelines.…”