Role of Magnetic Resonance Imaging in the Assessment of Perianal Fistulas

Objective: This study was carried out to evaluate the role of magnetic resonance imaging (MRI) in preoperative assessment of fistula-in-ano. Subjects and Methods: Twenty-six patients (21 male and 5 female, age 19–65 years) were prospectively studied from July 1999 to December 2001 using a 1.0-tesla superconducting magnet. T1-weighted fast spin echo (T1W FSE) images before and after gadolinium injection and fat suppressed T2-weighted fast spin echo (T2W FSE) images were obtained in transverse and coronal planes. MRI findings were correlated with surgical findings. Results: Twenty-one of the 26 patients demonstrated active fistulas. The MRI findings were in accordance with the examination findings under anesthesia and/or surgery in 15 of 16 cases. Both coronal and transverse planes were useful in assessing the location and direction of tracts and abscesses. Both contrast-enhanced T1W FSE and fat-suppressed T2W FSE images were useful in assessing the activity of lesions and the course of tracts. Conclusion: MRI showed accurate correlation with surgical findings and aided in preoperative management and planning for surgery.