Multi-parametric MRI in the early prediction of response to neo-adjuvant chemotherapy in breast cancer: Value of non-modelled parameters.

•A decrease in tumour volume of 71% after 2 cycles of NAC can predict pCR with a sensitivity of 74% and specificity of 77% (AUC=0.77).•A decrease in the enhancement fraction is the best metric for predicting pCR after 2 cycles of neoadjuvant chemotherapy.•Non-contrast enhanced-derived parameters such as the ADC and R2* were not useful in determining pCR after 2 cycles of NAC in breast cancer.•The enhancement fraction can be used as a surrogate semi-quantitative imaging biomarker to predict pCR to NAC at an early time point.•Use of a multi-parametric MRI model to assess early response to breast cancer emphasises the importance of the change in vascular parameters.