〔Abstract〕 Objective To observe the change of quantitative parameters of dynamic enhanced magnetic resonance(DCE-MRI) during neoadjuvant chemotherapy(NAC) in breast cancer, and to investigate the feasibility of predicting the pathological efficacy of breast cancer with NAC.Methods Eighty patients with breast cancer received NAC were retrospectively analyzed. All patients underwent surgery after chemotherapy were divided into pathological complete response(pCR) group and non-pCR group. Statistical analysiswas used to compare the changes and differenceof DCE-MRI quantitative parameters before and after NACbetween pCR and non-pCR group. Pearson correlation analysis was used to analyze the correlation between the changes of DCE-MRI parametersand Δd before and after NAC treatment. The receiver operating characteristic curve(ROC) was used to analyze the diagnostic efficacy of DCE-MRI quantitative parameters. Results The 34 cases of 80 cases with invasive carcinoma were pCR and 46 cases of that were non-pCR. There was no significant difference in d value between p CR group and non-pCR group before NAC( P = 0. 320). The perfusion transfer coefficient( Ktrans) and reflux rate( Kep) values of p CR group before NAC were statistically lower than those of non-pCR group( P<0. 05). The values of d,Ktrans,Kepand Vpafter NAC in p CR group were statistically lower than those before NAC( P<0. 05),and the values of d and Ktransafter NAC in non-pCR group were lower than those before NAC( P<0. 05). The ΔKtransand ΔKepvalues between pCR group and non-pCR group were statistically different( ΔKtrans: P = 0. 022,ΔKep: P = 0. 016). Correlation analysis showed that there was a positive correlation between ΔKtransand Δd after NAC( r = 0. 730,P<0. 001). The areas under the ROC of Ktrans,ΔKtrans和 Kepwere 0. 822,0. 747 and 0. 705 respectively. The sensitivity and specificity of the diagnosis were 84. 000% and 81. 200%,84. 000% and 74. 910%,76. 000% and 79. 800% respectively.Conclusion Ktrans,ΔKtransand Kephave higher diagnostic efficacy in predicting the pathological response of NAC in locally advanced breast cancer.