Synthetic MRI (syMRI) can quantify multiple relaxation parameters at the same time, which might have potential application value in the BI-RADS 4 lesions. 77 breast disease patients who were defined as BI-RADS 4 in the preoperative MRI examination were prospectively enrolled in this study. Before and after contrast injection, all patients underwent routine MRI and syMRI examinations. The result show that relaxation time and ADC values provided by syMRI and DWI are useful in distinguishing breast BI-RADS 4 lesions. The multi parameter model combined with clinical and imaging features can significantly improve the diagnostic ability of BI-RADS 4 breast lesions.