TI-RADS assesses the likelihood of malignancy according to the characteristics of thyroid nodules under ultrasound, which are classified into grades 1-5. Of these, grades 1-3 are more likely to be benign and can be observed with regular follow-up as long as there are no obvious symptoms of pressure or sudden increase in size in a short period of time. Among them, class 4 is further divided into 4a, 4b and 4c. For class 4 and 5 nodules, and the line may exceed 20% or even up to 100%, so fine needle aspiration is recommended to clarify the nature of the nodule, and if it is malignant, surgery is recommended.