Thyroid and parathyroid imaging

Abstract

With the advent of better thyroid function tests, a tumor marker, and fine-needle aspiration, the role of thyroid imaging studies in the evaluation of the patients with thyroid disease has diminished. Although multimodality thyroid imaging had improved our understanding of thyroid disease, current indications for thyroid imaging are the solitary or dominant thyroid nodule, an upper mediastinal mass, differentiation of hyperthyroidism, detection and staging of postoperative thyroid cancer, neonatal hypothyroidism, thyroid developmental anomalies, and the thyroid mass post-thyroidectomy for benign disease. To provide optimal, cost-effective, care for the thyroid patient, the physician must understand the advantages and disadvantages of each imaging modality--scintigraphy, real-time sonography (RTS), computed tomography, and magnetic resonance--in specific clinical settings. Similarly, preoperative noninvasive localization of hyperfunctioning parathyroid tissue in patients with primary hyperparathyroidism undergoing their initial neck exploration usually is not warranted. In this situation, the best localization procedure is to enlist the services of an experienced parathyroid surgeon. However, if this is not feasible because of local constraints, both sestamibi methoxy isobutyl isonitrile (MIBI) scintigraphy and magnetic resonance imaging (MRI) provide excellent localization (< 90%) of juxta-thyroidal and ectopic parathyroid adenomas. Hyperplastic glands are more difficult to detect because of their smaller size, and tandem studies (MIBI and MRI) should provide higher sensitivity before initial exploration, especially in patients with ectopic glands. In patients with persistent or recurrent disease, multimodality imaging with MIBI, MR, computed tomography and RTS in a sequential fashion is warranted to optimize two-test, site-specific localization.