Sonography of the Thyroid.

Nodular thyroid disease is very common, and the vast majority of nodules are benign. Sonography serves as an effective diagnostic tool in identifying nodular features that are concerning for malignancy and those with a benign appearance. The American College of Radiology has developed a risk-stratification system called the Thyroid Imaging Reporting and Data System, which uses the sonographic appearance of nodules combined with nodule size to determine the need for fine-needle aspiration or sonographic surveillance to diagnose malignancy. Familiarity with the sonographic appearance of diffuse thyroid disease allows differentiation of these conditions from nodular thyroid disease.