thyroid scanning, a radionuclear scan that determines the size, shape, position, and physiological function of the thyroid gland. It is useful in patients with neck or substernal masses, thyroid nodules, hyperthyroidism, metastatic tumors without a known primary site, and well-differentiated forms of thyroid cancer. The scan may focus either on the neck area only, or on the whole body (done in patients previously treated for thyroid cancer).
