The BI-RADS classification consists of two major parts, one for the conventional classification and one for the special classification. The conventional classification refers to categories 1 to 5, the higher the number, the higher the risk of malignancy. category 1 refers to normal breasts, no clear abnormal nodules or abnormal structures of the breast are found, which are judged as BI-RADS classification category 1 at this time. category 2 refers to definitely benign breast abnormalities, mainly including breast cysts and coarse calcified foci in the breast, some of the breast nodules with long-term follow up if they do not appear to grow, are also judged as BI-RADS classification category 2. Category 3 refers to breast nodules or abnormal structures that are probably benign and have a low risk of breast cancer, less than 2%. category 4 and 5 refer to breast nodules or abnormal structures that have a risk of malignancy, where the risk for category 4 is 2% to 90% and for category 5 is 95% or more. the BI-RADS classification also contains two special categories, one is category 0, which mainly refers to Category 6 refers to patients with pathologically confirmed breast cancer.