Degradation of hyaluronan by PEGPH20 can improve stromal-dense tumour response to therapy. Given PEGPH20 treatment is associated with a reduction in tumour water content, we hypothesised that T1, T2, MTR and ADC may inform on PEGPH20 response. MRI was performed before and after PEGPH20 treatment in 4T1 HAS3 and MDA-MB-231 LM2-4 orthotopic breast tumours. T1, T2, and ADC significantly decreased, and MTR significantly increased following PEGPH20 treatment in 4T1 HAS3 tumours. PEGPH20 significantly decreased ADC but did not change T1, T2 or MTR in MDA-MB-231 LM2-4 tumours. These data suggest that ADC can detect breast tumour response to PEGPH20.