Qualitative analysis of BI-RADS 4
malignancy
All patients with BI-RADS grade 4 lesions were diagnosed by a senior breast radiologist with 15 years of experience. The senior radiologist relied on the morphology (size, margin and internal enhancement pattern) and time–signal intensity curve (TIC) to assess the lesions in isolation and was blinded to the pathological results. BI-RADS category 4 corresponds to a likelihood of malignancy between 2 and 95% and is further divided into categories 4a, 4b, and 4c. According to the American College of Radiology and BI-RADS in 2013, the definitions of 4a/4b/4c are as follows [