A study on magnetic resonance imaging in patients having perianal pathology

Abstract

Introduction: Perianal region is a commonly affected area in the course of several inflammatory, infectious, and neoplastic diseases. Several imaging modalities are used in imaging evaluation of this area and magnetic resonance imaging (MRI) emerges as the imaging modality of choice due to its superb soft tissue resolution. MRI is not only useful for initial detection of perianal pathologies but also in the follow-up of these disorders. Magnetic resonance imaging (MRI), with its superb soft tissue resolution, is the imaging modality of choice for anal and perianal abnormalities. Pelvic phased array coils allow more comfortable and tolerable scans with higher signal-to-noise ratios and wider field of view. Parallel imaging techniques result in shorter scan durations T2-weighted images obtained with and without fat saturation as well as postcontrast T1-weighted images with fat suppression are the most helpful sequences. Postcontrast images are helpful, mainly for differentiating postoperative changes and chronic granulation or fibrotic tissue from active inflammation and abscess formation. Axial and coronal oblique images of the anal canal should be acquired with proper and accurate multiplanar prescription in order to get ideal images which are perpendicular and coronal to the anal canal. Materials and MethodsInclusion criteria: Patients with perianal discharge, swelling, pain or pruritus & diagnosed of having perianal pathology by MRI study (1.5 T MRI). Exclusion criteria: All patients referred to department of radiology, L G hospital, maninagar, Ahmedabad with rectal mass by MRI study (1.5 T MRI) All patients with contraindications to MRI like patients with metallic implants, claustrophobia, pacemakers and patients with contrast allergy. Study type: Retrospective study (record-based study). Consent not required for retrospective study. Results and Conclusion In our study of 50 patients, out of which 42 were males & 8 were females, the most common affected age group were between 25-35 years (42%). The most common location of fistula in our study was at 6'O -7'O clock (36%) position followed by 12-1'O clock (28%) position.  The most common type in our study being intersphincteric type (48%) according to PARK'S classification and the most common Grade in our study being grade 1 (simple intersphincteric fistula) (26%) according to St JAMES classification.  Adequate understanding of relevant pelvic anatomy and fistula classification on MRI examination is essential in providing proper assessment of perianal fistulas.  Evaluation of clinically undetectable disease has significant bearing on guiding medical & surgical therapy & can help minimize recurrence & better predict outcome compared to surgical exploration.