Abstract: Objective To evaluate the value of intravoxel incoherent motion(IVIM) parameters in a group of patients with pre-operative gliomas,predicting tumor grade in the solid tumor area and peritumoral edema areas,and its correlation with the expression of Ki-67.Methods A retrospective analysis of 51 patients with histopathologically confirmed gliomas was performed.All patients underwent brain MRI scan,enhanced and IVIM examination before operation,and the Ki-67 marker index of glioma was obtained by immunohistochemistry after operation.The IVIM parameters of the largest solid area of the tumor and the peritumoral edema area were measured respectively to obtain ADC,pure water diffusion coefficient(D),pseudo-diffusion coefficient(D*),and perfusion fraction(perfusion).fraction,f) value,Kruskal-Wallis test and Mann-Whitney U test were used to compare the differences of four quantitative parameters of tumor body area and peritumoral edema area between grades Ⅱ,Ⅲ,and Ⅳ and between high and low grade groups.The ROC curve was used to evaluate the diagnostic performance of each parameter in differentiating high and low grades of glioma.Spearman's method was used to analyze the correlation between IVIM quantitative parameters and Ki-67 labeling index.Results The ADC value of grade Ⅱ was higher than that of grade Ⅲ and Ⅳ,and that of low-grade glioma was higher than that of high-grade glioma;The D value of grade Ⅱ was higher than that of grade Ⅳ,and the low-grade glioma was higher than that of high-grade glioma;The D*value of grade Ⅱ and III is lower than grade Ⅳ.The f value of grade Ⅱ is lower than grade Ⅳ.In the peritumoral edema area,the ADC value of grade Ⅲ is higher than that of grade Ⅳ;The D value of grade Ⅱ glioma is higher than grade Ⅲ,and the D value of grade III glioma is lower than grade Ⅳ;There is no significant difference between the levels of D* value;The f value of grade Ⅱ glioma was lower than grade Ⅳ;Level Ⅱ f value is lower than level Ⅳ.There was no significant difference in the parameters of edema area between low and high-grade gliomas.Ki-67 was significantly correlated with ADC,D and D* of the solid tumor area.There was no significant correlation between Ki-67 and peritumoral edema parameters.Conclusions IVIM parameters of glioma solid tumor area can evaluate tumor grade non invasively and correlate with Ki-67.

Key words: magnetic resonance imaging, intravoxel incoherent motion, Glioma, Ki-67 labeling index, peritumoral edema invasion