BI-RADS is essentially a breast imaging reporting and grading system that classifies all nodules of unknown nature as risky on imaging, that is, to determine the probability of benign and malignant nodules with abnormal images. High probability is benign, and such nodules can be monitored closely by observation and follow-up. For nodules with grade 4 or higher, they represent the possibility of malignancy and are relatively risky, and puncture or excisional biopsy will be recommended to clarify the nature.