Ultrasonography is the method of choice for the evaluation of thyroid nodules. Thyroid nodules suspected on palpation or suggested on X-rays, CT, MRI, or PET. Ultrasound of the neck should be performed in all cases. Certain ultrasound signs can help distinguish benign from malignant thyroid nodules. Almost all thyroid nodules with the following two types of ultrasound changes are benign: 1) purely cystic nodules; 2) nodules with multiple small vesicles occupying more than 50 of the nodule volume with spongy changes, 99.7 are benign. The following ultrasound signs suggest the possibility of thyroid cancer: 1) solid hypoechoic nodules; 2) rich blood supply in the nodules; 3) irregular nodule shape and margin, halo absence; 4) microcalcifications, pinpoint-like diffuse distribution or clusters of calcifications; 5) abnormal ultrasound images of cervical lymph nodes, such as round lymph nodes, irregular or blurred borders, uneven internal echogenicity, internal calcifications, and poorly defined corticomedullary space. The lymph nodes were round, irregular or blurred borders, uneven internal echogenicity, internal calcification, poorly delineated corticomedullary, disappearance of lymphatic portal or cystic changes.