Thyroid and parathyroid imaging.

This article reviews the current roles of imaging in the diagnosis of thyroid and parathyroid disorders, with an emphasis on ultrasound evaluation. Imaging of the thyroid and parathyroid can be performed with nuclear medicine, ultrasound, CT, and MRI. Indications for thyroid and parathyroid imaging studies have recently changed. The availability of experienced endocrine surgeons, as well as the development of accurate laboratory tests, fine-needle aspiration (FNA) biopsy, and high-resolution ultrasound, have dramatically influenced the evaluation of thyroid and parathyroid disease. In patients with thyroid nodular disease, a clinical examination by an experienced clinician with appropriate lab values and palpation-guided FNA is the current diagnostic protocol of choice. Ultrasound evaluation of high-risk patients and ultrasound-guided FNA both augment this protocol when necessary. In patients with diffuse thyroid glandular disease, radionuclide imaging and color Doppler sonography both can be used for evaluation. When preoperative imaging is clinically necessary, sonography or scintigraphy can be used for parathyroid adenoma localization in patients with primary hyperparathyroidism. The recent development of technetium-99m sestamibi as a parathyroid imaging agent has improved the sensitivity of scintigraphy for parathyroid adenoma localization. Ultrasound and radionuclide imaging have also become valuable imaging techniques for parathyroid localization in patients with recurrent or persistent hyperparathyroidism.