Ch 6c--ULTRASONOGRAPHY of the THYROID

Thyroid ultrasonography (US) is the most common and extremely useful, safe, and costeffective way to image the thyroid gland and its pathology. US has largely replaced the need for scintiscanning except to detect iodine-avid thyroid metastases after thyroidectomy. This chapter reviews the literature; discusses the science and method of performing US; examines it’s clinical utility to assess thyroid goiters, nodules, cancers, post-operative remnants, cervical lymph nodes, and metastases; presents it’s practical value to enhance US-guided aspiration biopsy of thyroid lesions (FNA); and mentions it’s importance in medical education. US reveals, with good sensitivity but only fair specificity, very important and diagnostically useful clues to the clinician and surgeon about the likelihood that a thyroid nodule is malignant. Color flow Doppler enhancement of the US images that delineates the vasculature is essential. Comprehensive understanding of the local anatomy, the specific disease process, technical skill and experience are essential to proper interpretation of the US images. Features that favor the presence of a malignant nodule include decreased echogenicity, microcalcifications, central hypervascularity, irregular margins, an incomplete halo, a tall rather than wide shape, documented enlargement of the solid portion of the nodule and associated lymphadenopathy. Several of these attributes enhance the diagnostic probability. A patient’s history, physical examination, and comorbidities refine the diagnosis. FNA and cytological examination of thyroid nodules and adenopathy in adults, children, and adolescents has become a major, specific, and highly diagnostic tool that is safe and inexpensive. In addition, the aspirate maybe analyzed by evolving molecular genetic methods. For complete coverage of this and related areas in Endcorinology, visit our FREE web-text book, www.endotext.org.