PERIANAL FISTULA

EVALUATION OF THE PERIANAL FISTULA BY MRI: OUR EXPERIENCE

Abstract

MRI is increasingly used nowadays in the evaluation and management of Perianal
Fistula. Objectives: To assess the role of MRI in the detection and classification of Perianal
Fistula and correlation of preoperative MRI findings with the findings on surgery. Study Design:
Prospective study. Setting: Department of Radiology King Khalid Civilian Hospital Tabuk
Kingdom of Saudi Arabia. Study Period: Two years between February 2013 and February 2015.
Material and Methods: 60 patients were referred from surgical department for evaluation of
Perianal fistula by MRI during the above mentioned period. MRI was performed in 48 Patients.
(42 males and 6 Females) using variety of MRI sequences. Fistulas were classified according to
SJUH (St James’s University Hospital classification MR imaging based grading system) and MRI
findings of individual MRI sequence used were correlated with operative findings. Results: Most
common fistula was Grade 1 (37.5%).In majority of the cases internal opening was found at 6 O
clock position. Post intravenous contrast enhanced Axial and coronal oblique (CE FST1WFSE)
Fat suppressed T1 weighted Fast spin echo and Axial and coronal Fat suppressed T2W FSE
sequence (FST2WFSE) showed the highest Accuracies 98.13% and 97.06% respectively in
diagnosis of anorectal fistulae. Conclusion: MRI should be used as a first line imaging modality
in the preoperative assessment of Perianal fistula. Findings on Axial and coronal oblique CE
FST1WFSE, axial and coronal oblique FST2WFSE showed the excellent agreement with the
surgical findings. By using MRI as the first line imaging modality in the evaluation of Perianal
Fistula one can percept best possible surgical management resulting in prevention of residual/
recurrence disease and complications such as fecal incontinence.