Recent Advances of Magnetic Resonance Imaging in Evaluation of Recurrent Perianal Fistula

Background: Evaluation of recurrent perianal fistulae can be challenging; knowledge of relevant pelvic anatomy and fistula classification remains crucial in the diagnosis of recurrent perianal fistula. Magnetic Resonance Imaging (MRI) has been shown to demonstrate accurately the anatomy of the perianal region. In addition to showing the anal–sphincter mechanism, MRI clearly showed the relationship of fistulae to the pelvic diaphragm and the ischiorectal fossae, especially for patients with complex and recurrent fistulae. Objective: The aim of this study is to discuss the usefulness of high-resolution magnetic resonance imaging with contrast and/or local gel or saline injection in evaluation of recurrent perianal fistula. Methods: This prospective study included 30 symptomatic cases with suspected recurrent perianal fistula referred to Radiodiagnosis and Medical Imaging Department at Tanta University Hospitals through period extending from May 2017 to December 2019. MRI had been done for all selected patients. Perianal fistulas were classified according to the St James’s University Hospital classification. Results: Contrast enhanced MRI and local gel or saline injection showed 93.3% accuracy in detecting grade I, grade II and 100% accuracy with grade III, grade IV fistulae, ischeoanal abscesses and fibrotic tracts. Conclusion: Contrast enhanced MRI with local gel or saline injection in selective cases with external oozing opening is a very useful procedure for successful management of recurrent peri-anal fistula by correct assessment of the extent of fisulae, relationship to sphincter complex, detection of secondary tracts and abscesses, aiming to reduce complications and recurrences.