Thyroid nodules are very common and most are benign, but ultrasound is essential for characterization and risk stratification. Thyroid ultrasound evaluates nodule echogenicity, composition, margins, calcifications, shape, and vascularity to determine malignancy risk using the ACR TI-RADS or ATA classification systems.
TI-RADS Classification
The ACR Thyroid Imaging, Reporting and Data System (TI-RADS) assigns points based on five sonographic categories and determines whether follow-up or fine-needle aspiration biopsy (FNA) is recommended based on total score and nodule size.