Objective To examine the prediction value of diffusion-weighted magnetic resonance imaging (DWI) on radiotherapy response in esophageal cancer.Methods A total of 24 subcutaneous esophageal cancer xenograft models were randomly divided into experimental group (n =14,received a single dose of 15 Gy radiotherapy) and control group (n =10,without any treatment).MRI were required before and after radiotherapy at different check time points (1,6,13 days) of T1WI,T2WI,and DWI measurements.Apparent diffusion coefficient (ADCX) and volume (VX) of each xenograft were measured,and both △ADCX and △VX were calculated.Results The ADC values of both group were decreased at the first day,however,the decrease in experimental group were more obviously with an increase at 6 and 13 d gradually.However,the ADC values of the control group showed a persistent decline.There was no significant difference in the ADC values between the two different groups before radiotherapy (P ＞ 0.05),while significant difference was found in the ADC values (F =6.178,16.181,58.733,P ＜ 0.05) and △ADC after radiotherapy (F =9.038,12.360,35.140,P ＜ 0.05).The xenografts volume in the experimental group showed a significant growth delay.There was no significant difference in volume between the two groups (P ＞ 0.05) before radiotherapy.Significant difference in V between the two groups only began to exist at 5 d after radiotherapy (F =28.587,P ＜ 0.05).The ADC0,ADC1 of transplanted tumor in control group had linear correlation relationships with its volume of later period.After radiotherapy,the trend of r values gradually increased from-0.118 to 0.896.Conclusions ADC values may change significantly at the early stage after radiotherapy,and initial and early ADC value may have close relationship with xenograft volumes of later period,which indicates that DWI has huge potential in the prediction of radiotherapy response.