Diagnostic use of ultrasonography in patients with nodular thyroid disease.

OBJECTIVE To review the published reports pertaining to the diagnostic utility of ultrasonography for evaluation of thyroid nodules. METHODS Various roles for diagnostic thyroid ultrasonography and screening ultrasound studies of the thyroid are discussed, and ultrasound characteristics of thyroid nodules and their association with malignant potential are described. RESULTS In two studies that correlated ultrasound findings with physical examination findings in patients with a solitary thyroid nodule detected by palpation, 16% of such patients had no corresponding nodule evident on ultrasonography, and 45% of such patients had an additional nodule detected by ultrasonography. Similarly, approximately 18% of patients with a palpable multinodular thyroid had no nodules larger than 1 cm in diameter on ultrasound studies. Thyroid nodules larger than 1 cm have been found by ultrasonography to be present in from 2 to almost 5% of the population with normal findings on examination of the thyroid. Use of screening ultrasound study of the thyroid has been suggested for patients with a history of childhood irradiation to the head and neck or a family history of thyroid cancer. Numerous investigations that have evaluated ultrasound features of thyroid nodules have suggested five characteristics as suggestive of malignant potential--hypoechogenicity, microcalcifications, irregular or microlobulated border, absent or irregular thick halo, and increased intranodular vascularity. CONCLUSION Correlation of ultrasound and palpation findings will provide a comprehensive evaluation of nodular thyroid disease. Moreover, real-time ultrasonography facilitates characterization of features associated with an increased risk of a malignant lesion. High-resolution thyroid ultrasonography is a dynamic tool for endocrinologists.