Application of MRI Images Based on Autoregressive Model Algorithm in Diagnosis and Classification of Anal Fistula Disease

Abstract

Objective: To analyze the accuracy of DWI-MRI combined with conventional MRI sequence in the diagnosis and classification of anal fistula, and to explore its application value. Methods: The clinical and imaging data of 56 patients with anal fistula confirmed by surgery were collected. All patients underwent conventional MR scans (axial T1WI, T2WI and axial, coronary, sagittal T2WI fat suppression) and axial DWI. With the surgical pathology results as the gold standard, the diagnostic compliance rate of anal fistula inside and outside mouth, main fistula, branch fistula, and abscess were observed and relied on both conventional sequence and conventional sequence combined with DWI. At the same time, the patients in this group were classified according to Parks classification of anal fistula, and the results were compared with the surgical results. Results: Fifty-six patients with anal fistula were confirmed to have 7 simple anal fistulas and 49 complicated anal fistulas. According to Parks anal fistula classification, MRI diagnosed 7 cases of intersphincteric fistula, 24 cases of trans sphincteric type fistula, 16 cases of superior sphincteric type fistula, and included 9 cases of rectal vaginal/scrotal fistula into the scope of extra-sphincteric fistula. The overall coincidence rate of scores was 87.5% (49/56). Conclusion: In preoperative MRI examination of anal fistula, compared with relying only on conventional sequences, the combined use of DWI sequences has higher accuracy in displaying the inner, outer and branch fistulas, and provides more detailed images before clinical operation. Anatomical information should be applied as a routine examination sequence for preoperative diagnosis of anal fistula.