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Aim: This study was to evaluate the value of diffusion-weighted imaging (DWI) in predicting the efficacy of radiotherapy for esophageal cancer from xenograft model level., Subjects and Methods: Thirty-two tumor-bearing mice from the Eca-109 cell line nude mice models were established. The experimental group (n = 16) received a single dose of 15 Gy (6MV X-ray), whereas the control group (n = 16) did not receive any treatment. The tumor volume and apparent diffusion coefficient (ADC) were obtained. The cell density, tissue necrosis ratio, and CD31 expression were determined at matched time points., Results: The tumor volume was smaller in the experimental group than in the control group (P < 0.05) on the 7 th day after radiotherapy (1.580 ± 0.965 cm 3 vs . 2.671 ± 0.915 cm 3 ). The ADC values were higher in the experimental group than in the control group on the 3 rd day (P < 0.05) (998.15 ± 163.76 ×10 - 6 mm 2 /s vs. 833.32 ± 142.15 ×10 - 6 mm 2 /s). On the 3 rd day after radiotherapy, the differences in cell density and necrosis ratio between the two groups were statistically significant; the tumor cell density was lower in the experimental group (25.56 ± 1.40%) than in the control group (33.48 ± 4.18%) (P < 0.05), and the proportion of tissue necrosis was higher in the experimental group (32.19 ± 1.21%) than in the control group (29.16 ± 2.16%) (P < 0.05). The negative and weak positive rate of CD31 expression in the experimental group was higher than the control group, whereas the generally positive and strong positive rate of CD31 expression was significantly lower than the control group in the early stage (P < 0.05)., Conclusion: ADC values may change at the early stage before the morphological changes of tumors. Changes in cell density and necrosis ratio of transplanted tumors correspond to the changes in ADC values. DWI can be used for the early prediction of esophageal cancer radiotherapy efficacy., Competing Interests: None

The aim of the present study was to assess the predictive value of diffusion kurtosis imaging (DKI) on the effects of radiotherapy in a xenograft model of esophageal cancer. A total of 40 tumor-bearing mice, established by injection of Eca-109 cells in nude mice, were used. The experimental group (n=24) received a single dose of 15 Gy (6 MV by X-ray), and the control group (n=16) did not receive any treatment. Tumor volume, apparent diffusion coefficient (ADC), mean kurtosis (MK) and mean diffusivity (MD) of the two groups were compared, and the expression of aquaporin (AQP) 3 and necrosis ratio at matched time points in xenografts were also observed. There was a significant difference between the two groups from the 7th day of radiotherapy onwards; the xenograft volume of the experimental group was significantly smaller compared with the control group (P<0.05). On the 3rd day, the ADC and MD of the experimental group was significantly higher compared with the control group, and MK was significantly lower compared with the control group (P<0.05). On the 3rd day, AQP3 expression in the experimental group was lower compared with the control group, and the proportion of necrotic cells was higher compared with the control group (P<0.05). Single large fraction dose radiotherapy inhibited the growth of a xenografted esophageal tumor. Changes in ADC, MK and MD were observed prior to morphological changes in the tumor. The change in AQP3 expression and necrosis ratio was in also agreement with the DKI parameters assessed. DKI may thus provide early predictive ability on the effect of radiotherapy in esophageal carcinoma. [ABSTRACT FROM AUTHOR]