Abstract: A total of 83 patients with complex anal fistula in our hospital were selected as the observation group, and 80 healthy patients were selected as the control group during the same period. All patients underwent magnetic resonance imaging-diffusion weighted imaging (MRI-DWI) examination. The apparent diffusion coefficient (ADC) value and perianal disease activity index (PDAI) of the two groups were counted. The results showed that ADC value was negatively correlated with the score of abnormal perianal excretion, as well as the scores of complicated perianal type and perianal induration (P<0.05). The ROC curve showed that the area under the curve (AUC) of ADC in the diagnosis of complex anal fistula was 0.826, and the diagnostic sensitivity and specificity were 85.54% and 66.25%, respectively. It can be seen that there is a certain correlation between ADC value and perianal disease activity, efficacy and perianal function in patients with complex anal fistula. Early use of MRI-DWI technology can provide auxiliary imaging methods for the diagnosis and treatment of complex anal fistulas, as well as for the judgment of disease severity and prognosis evaluation.

Key words: MRI-diffusion weighted imaging technique, complex anal fistula, apparent diffusion coefficient, anal function