MATERIAL AND METHODS This prospective observational study was carried out on 80 patients in SS institute of medical sciences, Davangere, Karnataka with main source of data for the study were patients from S.S. Institute of medical sciences Davangere and clinical inputs, illustrations from Dr. B.R. Ambedkar Medical college, Bangalore. The study period was 2 years (May 2017 to May 2019). This study was based on prospective analysis of 40 patients with clinical diagnosis of perianal fistulae. This MRI preoperative analysis of perianal fistulae revealed total 40 patients with fistulous tract. The principle objective of this study was to classify the perianal A B S T R A C T Introduction: A fistula-in-ano is an abnormal hollow tract or cavity that is lined with granulation tissue and that connects a primary opening inside the anal canal to a secondary opening in the perianal skin; secondary tracts may be multiple and can extend from the same primary opening. Radiograph and Computed tomography has become obsolete investigation. In this study we gave an outline of classification of perianalfistulae and present a pictorial assay of sphincter anatomy and USG, MRI findings inperianal fistulae. Material and methods: This prospective study had been carried out with main source of data for the study were patients from S.S. Institute of medical sciences Davangere and clinical inputs, illustrations from Dr.B.R. Ambedkar Medical college, Bangalore. This study is based on prospective analysis of 40 patients with clinical diagnosis of perianal fistulae. Results: In the present study, On Radiological evaluation we found that-In 40cases 32 patients had single tract (80%), 8 cases had multiple tracts (20%). 38 cases(95%) had single external opening, rest of 2 cases (5%) multiple external opening. 33(82.2%) cases shows ramification. 26 cases (65%) intersphincteric fistulae seen. 12cases (30%) Transphincteric fistulae seen.2 cases (5%) extrasphincteric fistulae seen. The 8 cases were presented with swelling. Conclusion: Radiograph and computed tomography do not provide much details and can be consider as obsolete investigation. The endo-anal ultrasound approach was entirely helpful for evaluating the sphincteric course of fistula, but gives no mind about the extrasphincteric course which made magnetic resonance imaging more acceptable technique for evaluating perianal fistula since it presents an estimate about the extrasphincteric course. MR imaging provides precise location of the fistulous track, and its relationship to pelvic floor and the sphincter complex and helps in the identification of secondary tracks and abscesses. Hence forth the present study showed that MR imaging provides precise location of the fistulous track, and its relationship to pelvic floor and the sphincter complex and helps in the identification of secondary tracks and abscesses

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