Objective:To investigate the value of synthetic MRI quantitative parameters in identifying different molecular types of breast cancer and triple negative breast cancer (TNBC) and non-TNBC.Methods:A retrospective analysis was performed on 208 patients diagnosed with invasive ductal breast cancer in the First Affiliated Hospital of China Medical University from March 2019 to September 2020. All patients underwent synthetic MR examinations and the following quantitative parameters were measured, including tumor diameter, volume, apparent diffusion coefficient (ADC), and corresponding values of T 1, T 2, and proton density (PD). According to the immunohistochemical results, there were 122 cases of progesterone receptor (PR) positive and 86 cases of PR negative, 123 cases of estrogen receptor (ER) positive and 85 cases of ER negative, 79 cases of human epidermal growth factor receptor-2 (HER2) positive and 129 cases of HER2 negative, 149 cases of Ki-67 high expression and 59 cases of Ki-67 low expression; there were 36 cases of TNBC and 172 cases of non-TNBC. Independent samples t test or Mann-Whitney U test were used to compare the quantitative parameters of different molecular types, TNBC and non-TNBC patients. Multivariate logistic regression was used to analyze independent predictors of TNBC, and receiver operating characteristic curve and area under the curve (AUC) were used to evaluate the efficacy of sole and combined parameters in identifying TNBC. Results:T 1 and T 2 values in PR negative breast cancer patients were higher than those in PR positive patients ( t=2.30, Z=2.04, P<0.05); the values of T 1 and T 2 in ER negative patients were higher than those in ER positive patients ( t=2.52, Z=2.48, P<0.05); ADC value and tumor diameter of HER2 positive patients were larger than those in HER2 negative patients ( t=-3.21, Z=-3.22, P<0.05). T 2 value, tumor volume and diameter in patients with Ki-67 high expression were significantly higher than those in patients with Ki-67 low expression ( Z=-3.47, -2.51, -2.84, P<0.05); ADC value in Ki-67 high expression group was less than that in Ki-67 low expression group ( t=3.94, P<0.001). T 1, T 2 values and tumor volume in TNBC patients were higher than those in non-TNBC patients ( t=-3.26, Z=-5.58, Z=-2.02, P<0.05], and ADC value in TNBC patients was lower than that in non-TNBC patients ( t=3.07, P=0.002). Multivariate logistic regression analysis showed that T 2 (OR=1.060, 95%CI 1.028-1.093, P<0.001) and ADC value (OR=0.947, 95%CI 0.911-0.984, P=0.005) were independent predictors of TNBC. The efficacy of each parameter alone and in combination to identify TNBC showed that the T 2 value in the single parameter had the largest AUC (0.759), and there was no significant difference between T 2 value and its combined parameters in the diagnosis of TNBC. Conclusions:The quantitative parameters based on synthetic MRI, especially T 2 value, have value in differentiating different molecular types of breast cancer, TNBC and non-TNBC may be another non-contrast parameter for evaluating tumor aggressiveness beyond ADC value.