It is known that benign and malignant breast cancer feature different T1 relaxation, the use of T1 relaxation in differential diagnosis has been reported. However accurate measurement of T1 relaxation requires knowledge of B1 distribution, which is inhomogeneous in breast. Synthetic MRI offers B1 corrected T1 relaxation time, its use breast cancer diagnosis has not yet been reported. Here, the use of the T1 mapping in synthetic MR in differential diagnosis of benign and malignant cancer is investigated. Our results demonstrated that T1 mapping offered by synthetic MR may be a potential quantitative biomarker for diagnosis of breast cancer.