Advances in multimodal imaging for adrenal gland disorders: integrating CT, MRI, and nuclear medicine

Adrenal diseases pose significant diagnostic challenges due to the wide range of neoplastic and non-neoplastic pathologies. Radiologists have a crucial role in diagnosing and managing these conditions by, leveraging advanced imaging techniques. This review discusses the vital role of computed tomography (CT), magnetic resonance imaging (MRI), and nuclear medicine in adrenal imaging, and focuses on morphological and functional evaluations. First, the anatomy and physiology of the adrenal glands are described, followed by a discussion on ectopic adrenocortical adenomas and how they develop. The concepts and imaging findings of congenital diseases, such as congenital adrenal hyperplasia (CAH), adrenal rest tumors, and adrenocortical nodular disease, considering recent updates to the WHO Classification of Tumours (5th ed.) terminology are highlighted. The diagnostic value of dynamic contrast-enhanced CT and chemical-shift MRI for identifying adrenocortical adenomas are emphasized, alongside the use of adrenocortical scintigraphy such as ¹³¹I-adosterol scintigraphy for diagnosing Cushing's disease, Cushing's syndrome (CS), subclinical CS, and ectopic adrenocorticotropic hormone-producing tumors. Systemic complications associated with CS, and the diagnosis and treatment of pheochromocytomas, paragangliomas (PPGLs), and neuroblastomas, will also be discussed focusing on ¹²³I-metaiodobenzylguanidine (MIBG) imaging and ¹³¹I-MIBG therapy. Pitfalls in ¹²³I-MIBG imaging and the increasing importance of diagnosing hereditary PPGLs due to increased genetic testing are also be discussed. Additionally, the broad differential diagnosis for adrenal masses-including malignancies like adrenal carcinoma, metastases, and malignant lymphoma, as well as benign conditions like myelolipoma and ganglioneuroma, and complications, such as adrenal hemorrhage, infarction, and infections-will be outlined. The goal of this review was to provide an overview of adrenal diseases that includes the most recent information for radiologists to stay updated on the latest imaging techniques and advancements that can ensure accurate diagnosis and effective management.