1. Differential diagnosis by ultrasound of thyroid diseases 1. Localization: determine the source of the lesion, whether it is the thyroid gland, parathyroid glands or other surrounding tissues, etc.; 2. 4. Identify the presence or absence of lymph nodes in the neck and the benignity or malignancy of the lymph nodes: in general, microcalcifications, cystic changes, and cortical thickness >3 mm in the lymph nodes may be malignant metastatic tendencies. Description of ultrasound report of diffuse thyroid lesions 1. measurement of thyroid size: upper and lower diameter / anterior and posterior diameter / left and right diameter, isthmus; 2. morphology: symmetric or asymmetric; 3. gland boundary: clear and ambiguous; 4. echogenicity: normal, hypo-echoic and hyper-echoic, with reference to normal submandibular gland parenchymal echogenicity; 5. echogenicity: uniform or inhomogeneous; 6. degree of blood supply: The degree of blood supply: normal, increased or decreased, keeping in mind special blood flow manifestations such as the “sea of fire sign”; 3. Description of ultrasound report of limited thyroid lesions 1: 3. size: upper and lower diameter, anterior and posterior diameter, left and right diameter, and aspect ratio; 4. morphology: round, oval, round-like, irregular; 5. border: clear or ambiguous, invasion of the peritoneum and surrounding tissue structures; peripheral halo: 1. regular halo: complete, narrow, uniform thickness – benign signs; 2. irregular halo: incomplete, wide 2. Irregular corona: incomplete, wide, uneven thickness – malignant signs; here we would like to remind you that medullary thyroid carcinoma can also be a regular nodule with clear borders, so you need to pay attention to differentiation and malignant signs in the nodule. 1. solid nodules, solid predominant nodules, cystic predominant nodules, cystic nodules; 2. type and number of calcifications: we need to note that the glial matter within the nodule is also punctate with strong echogenicity, but this is followed by a comet tail sign, which is a differentiating point from microcalcifications; 3. posterior echogenicity: enhancement, no change or attenuation, posterior echogenicity attenuation of hypoechoic nodules is generally a malignant sign; blood flow typing: malignant: no peripheral vessels Surrounding vessels <1/2 circle, penetrating blood flow, irregular distribution of internal blood flow; Amphoteric: Surrounding vessels >1/2 circle, no obvious penetrating blood flow, regular distribution. In the examination of focal thyroid lesions, attention should be paid to identify the inflammatory focal lesions and not to assume that they are occupying lesions; 2. metastatic signs; 4. Hashimoto’s thyroiditis generally manifests as diffuse enlargement of the thyroid gland, in which isthmus enlargement is also more obvious; 5. Subacute thyroiditis: there is mostly pressure pain (there are also those without pain), and ultrasound manifests as washout sign; 6. For uncertain lesions, nuclear scan and thyroid function test can be recommended, and for those who suspect medullary carcinoma, blood calcium test is recommended; 7. Patients should be reviewed once every three months (although some thyroid lesions may have slow cycle changes, and some papillary carcinomas may even grow only a few millimeters for more than a decade).