Objective:To clarify the evidences of hippocampal injury after radiotherapy avoiding hippocampus and explore its relationships with cognition.Methods:A prospective design was adopted in this study.A total of 183 patients with nasopharyngeal carcinoma treated by intensity modulated radiation therapy (IMRT group) and 30 matched healthy control (HC group)were collected in the Affiliated Hospital of Jiangsu University and Southeast University Affiliated Zhongda Hospital from January 2017 to December 2019. All subjects were assessed by Montreal Cognitive Assessment (MoCA-B) at baseline and 6 months after radiotherapy, then the patients with nasopharyngeal carcinoma were divided into cognitive impairment group and non-cognitive impairment group. Subjects were scanned with Siemens 3.0 T MR, and T 1WI was used as analysis sequence.The individual standardized hippocampus ROIs were extracted based on Montreal Neurological Institute(MNI) brain template.All texture features were calculated using the Radiomics developed by C++and Delphi, and the intra group correlation coefficients (ICC), average direction, machine learning (random forest) and autocorrelation matrix were used for reducing the features dimension. One-way ANOVA and generalized linear models were used to compare the differences among different groups. Pearson correlations analyses were used to evaluate the relationships between important texture features and clinical data. Logistic regressions were used to calculate the abilities of texture features to predict cognitive impairment. Results:After 9 patients who lost follow-up were excluded, a total of 164 patients with nasopharyngeal carcinoma were included as IMRT group.Texture features of ROIs were extracted and dimensionally reduced successfully. Five differences features (Variance, Entropy, GlevNonU, RLNonUni and Contrast)were found among HC group, cognitive impairment group and non-cognitive impairment group, and the last three further showed significant differences within IMRT group (GlevNonU, P=0.011;RLNonUni, P<0.001;Contrast, P<0.001). Hippocampal doses were positively correlated with Variance ( r=0.448, P<0.05), and negatively correlated with Entropy ( r=-0.461, P<0.05). There was a positive correlation between MoCA-B scores with GlevNonU, RLNonUniand Contrast ( r=0.503, P<0.05; r=0.587, P<0.05; r=0.531, P<0.05). GlevNonU and Contrast were independent predictors of cognitive impairment in hippocampal avoidance of radiotherapy (OR=0.731, 95%CI 0.610-0.857; OR=0.651, 95%CI 0.496-0.853). Conclusion:Results of texture analysis could be used as micro imaging evidences of hippocampal injury in radiotherapy avoiding hippocampus, and could also effectively predict the occurrences of cognitive impairment.