A thyroid nodule is a discrete growth or lump within the thyroid gland. Thyroid nodules are extremely common — detectable by ultrasound in up to 50 to 67 percent of the general population — but the vast majority are benign. On ultrasound, nodules are characterized by their composition (solid, cystic, or mixed), echogenicity (hyper-, iso-, or hypoechoic), margins (smooth, irregular, or lobulated), the presence of calcifications (microcalcifications, macrocalcifications, or rim), and shape (wider-than-tall or taller-than-wide). These features are used in the TI-RADS (Thyroid Imaging Reporting and Data System) classification to assign a risk category and determine whether biopsy is recommended based on the nodule’s size and suspicion level. Ultrasound is the primary tool for detecting, characterizing, and monitoring thyroid nodules over time.
Sonography Term