Magnetic Resonance Imaging of Fistula-in-ano

Fistula-in-ano is a highly devastating disease due to its high morbidity. In order to achieve excellent surgical outcome, preoperative evaluations are essential. Magnetic resonance imaging (MRI) allows high spatial resolution images and is highly accurate in delineating the type and extent of a perianal fistula. MRI has also been shown to markedly diminish recurrence by improving preoperative planning. Therefore, preoperative pelvic MRI has already become routine in the management of perianal fistula. Adequate knowledge of the relevant pelvic anatomy, pathophysiology, fistula classification, and their implications on the therapeutic options is the key for proper MRI assessment of perianal fistula. This pictorial essay discusses these topics.