BI-RADS is the Breast Imaging Reporting and Data System, which was introduced by the American College of Radiology in 1992. The BI-RADS classification is now used to guide not only mammography, but also ultrasound and MRI. According to the BI-RADS grading criteria mammography, ultrasound and MRI findings are classified into 0-6 grades with the following meanings: Grade 0: incomplete assessment, other imaging is needed: Grade 1: no abnormalities seen on imaging; Grade 2: imaging findings are benign signs; Grade 3: imaging suggests a high likelihood of benignity; Grade 4: imaging suggests suspicious malignancy, according to the degree of risk. 4A (malignant likelihood 3-8%) 4B (malignant likelihood 9-49%) 4C (malignant likelihood 50-94%) three subgrades; Grade 5: three or more signs suggesting malignancy, with a high malignant likelihood of ≥95%; Grade 6: lesions that have been confirmed to be malignant by puncture or surgical pathology. The BI-RADS also provides recommendations for the management of graded breast lesions. Grade 0 population is incompletely evaluated and requires additional imaging; Grade 1 population is normal and does not require treatment; Grade 2 are benign breast lesions, such as: lobular hyperplasia mammary adenopathy, breast cysts, fibroadenoma, etc., which are treated according to clinical routine Grade 3 suggests a high likelihood of benignity and less than 3% risk of malignancy, which is recommended to be reviewed after 3-6 months; Grade 3 lesions include: breast first detected in patients >25 years old Fibroadenoma, mammary adenomatous hyperplasia, complex cysts of the breast, etc. Grade 4 lesions have a high possibility of malignancy and often require ultrasound-guided biopsy to clarify the diagnosis before treatment; Grade 5 lesions are equivalent to breast cancer that has not been confirmed by pathological examination and require inpatient surgery, chemotherapy or radiation therapy; Grade 6 lesions are breast cancer that has been pathologically confirmed and imaging It is mainly used for pre-treatment evaluation or post-treatment efficacy determination.