Objective:To investigate the changes of brain microstructure in active Crohn's disease (CD) patients with or without anxiety by diffusion kurtosis imaging (DKI), and to explore the relationship between brain microstructure and anxiety in patients with CD.Methods:Thirty-seven patients with CD who were treated in Changzhou Second People's Hospital Affiliated to Nanjing Medical University from January 2022 to January 2023 were included as the CD group, and 20 healthy subjects were included as the healthy control group during the same period. All subjects were assessed with hospital anxiety and depression scale-anxiety (HADS-A) before magnetic resonance imaging(MRI) scan. According to the HADS-A score, CD patients were divided into the CD group with anxiety (16 cases) and the CD group without anxiety (21 cases). After MRI scan, DKI parameters were obtained by DKE software. One-way analysis of variance was used to compare DKI parameters between the two groups of CD patients and the healthy control group. Pearson correlation was used to analyze the correlation between DKI parameters in different brain areas and psychological scale scores in the two groups of CD patients.Results:The axial diffusion kurtosis(AK)values in the right insula, the left superior temporal gyrus, the right thalamus, the left middle temporal gyrus, the right inferior temporal gyrus, the left lingual gyrus and the right anterior cuneus were significantly different among the three groups ( F=3.060-9.627, all P<0.05).There were significant differences in the radial diffusion kurtosis(RK) values in the right cerebellar region 6 and the left hippocampus among the three groups ( F=4.124, 3.536, 4.200, all P<0.05). Further multiple comparison results showed that the AK values of the right insula (0.701±0.028)( P=0.019), the left superior temporal gyrus (0.764±0.016)( P=0.002) and the right thalamus (0.728±0.016)( P=0.001) in the CD group without anxiety were lower than those of the healthy control group(0.726±0.010, 0.780±0.015, 0.771±0.082), and the RK value of the right cerebellar region 6 ( P=0.021) was lower than that of the healthy control group. The AK values of the right insula ( P=0.023), the left superior temporal gyrus ( P=0.015), the right thalamus ( P=0.031), the left middle temporal gyrus ( P=0.006), the right inferior temporal gyrus ( P=0.001) and the left lingual gyrus ( P=0.007) in the CD group with anxiety were lower than those in the healthy control group. The RK values of right cerebellar region 6 ( P=0.012) and left hippocampus ( P=0.004) were lower than those of healthy control group. The AK values of the right insula ( P=0.002) and the right anterior cuneus ( P=0.017) in the group with anxiety were lower than those in the CD group without anxiety. In the CD group with anxiety, the AK value of the right insula was correlated with erythrocyte sedimentation rate(ESR)( r=-0.47, P=0.048), HADS-A score ( r=-0.68, P=0.002), SES-CD( r=-0.84, P<0.001) and duration of disease ( r=-0.61, P=0.008) were negatively correlated. AK values in the left superior temporal gyrus with anxiety CD group were negatively correlated with HADS-A score ( r=-0.51, P=0.030) and SES-CD score ( r=-0.48, P=0.046). Conclusion:The microstructure of some brain regions was damaged in CD patients with or without anxiety, which was manifested as decreased RK and AK values in DKI parameter values, which may be related to the anxiety state in active CD patients.