Perianal fistulas in Crohn's disease: MRI diagnosis and surgical planning: MRI in fistulazing perianal Crohn's disease.

Crohn's disease is a chronic, transmural inflammatory process of the gastrointestinal tract. It often affects the colon with the perianal area. The most common intestinal manifestations include external and/or internal fistulas and abscesses. Assessment of the activity of perianal fistulas in the course of Crohn's disease seems to be an important factor influencing therapeutic approach. Fistula's activity is evaluated by such methods as magnetic resonance imaging, anal ultrasound and examination under anaesthesia. Usefulness of imaging methods in the diagnosis of fistulas still remains to be defined.MRI is used to present a wide spectrum of perianal fistulazing Crohn's disease. Additionally, it is an important instrument revealing location, extent and severity of inflammation. It is also very helpful to detect clinically silent sepsis related to small, local inflammation. The most common method used in MR imaging to assess topography of a fistula's track, is Parks' classification.Clinical indications to MRI may include follow-up studies of a diagnosed disease, classification of fistulas' subtypes in the course of Crohn's disease, determination of the extent of fistulas' tracts and spread of an inflammatory process what can guide surgical procedures.