Magnetic resonance imaging of perianal fistula: what could it add to the clinical diagnosis?

Background: Perianal fistula is a chronic inflammation that may be simple or complex. It mainly affects adult males. Their precise diagnosis is important as improper evaluation could result in many unnecessary operations or serious post-operative complications. Aim of work: Was to describe MRI findings of different types of perianal fistulas and to enhance its role in adding great information to the surgeon. Patients and Methods: The study population comprised of 58 patients ranging in age from 8 to 68 years with clinical evidence or suspicion of anal fistulas. MRI was done using phased array coil, before and after IV contrast, using multiple pulse sequences i.e. T1, T2 and STIR. Findings were classified according to St. James classification into 5 grades. Results: MRI could prove the presence of fistula in 82.8% of patients. Maleto female ratio = 3:1. Most fistulas were of grade 1 and 2 (38.2%), 62.5% was single. Most internal openings were located at 6 o’clock (89.5%). 25.9% showed post contrast enhancement of the fistulous track and 5.2% showed enhancement within abscess lesions. Conclusion: MRI is ideal in diagnosing and grading of perianal fistulas and in detecting associated complications that add much to the clinical examination.