[Imaging diagnostics of hyperparathyroidism]

Primary hyperparathyroidism is diagnosed by the presence of hypercalcemia, hypercalciuria and elevated serum levels of parathyroid hormone and is treated surgically by removal of the enlarged gland. Both ultrasound and 99m-Tc-MIBI scintigraphy are used to localize enlarged parathyroid glands. With sonography, enlarged parathyroid glands are hypoechoic and are most frequently found dorsally or caudally to the thyroid and medially to the carotid arteries. Ectopic parathyroid glands in the mediastinum can be detected by scintigraphy only. Computed tomography and magnetic resonance imaging are not primarily indicated. The sensitivity of ultrasound is 90% at best. Causes for false negative ultrasound examinations are ectopic glands in the mediastinum, small glands weighing less than 200 mg and large goiters which make assessment of the retrothyroid space difficult. Ultrasound and scintigraphy in combination can achieve a sensitivity of more than 90%. A combination of both is indicated prior to minimally invasive resection and in cases of recurrence or persistence of hyperparathyroidism after resection.