No blood flow signal was seen in breast nodule 4A, suggesting that the nodule is low malignant, but malignancy has not been ruled out, and a puncture biopsy is recommended. In the diagnostic imaging of the breast, there is the BI-RADS classification, which divides breast nodules into seven categories, and category 4 is divided into three levels, with 4A, 4B, and 4C representing low (2%-10%), moderate (10%-50%), and high (50%-95%) malignancy, respectively. Breast nodule 4A No blood flow signal is the presentation of breast nodule on ultrasound image, which is a description of the nodule from the imaging physician in terms of morphology, size, borders, and internal echoes. The absence of blood flow signal indicates that there is no neovascularization around the nodule, which means that the nodule may be proliferating or the proliferation is not very active, but it is also possible that the malignant nodule is too small to detect the blood flow signal. Blood flow signal is not a very sensitive indicator, so we can’t judge whether a nodule is benign or malignant solely by the presence or absence of blood flow signal, and we need to do further examination to clarify the nature of the nodule, which is usually done by puncture biopsy in clinical practice.