Finding a Needle in a Haystack: Review of Imaging to Identify Parathyroid Adenoma

Primary hyperparathyroidism is characterized by hypercalcemia secondary to increased production or altered excretion of the PTH. Primary hyperparathyroidism is the most common cause of primary hypercalcemia. This is typically caused by parathyroid adenomas. A parathyroid adenoma can be difficult to localize given its small size and occasional ectopic location. With the advent of newer imaging techniques and the intraoperative PTH assay, directed minimally invasive surgery has replaced the standard 4-gland exploration for resection of single-gland adenomas. For minimally invasive surgery, precise preoperative localization of the adenoma is critical. We aim to review the anatomy, embryology, and different imaging modalities helpful in diagnosing parathyroid adenomas, with particular emphasis on efficacy and limitation.