DIAGNOSTIC ACCURACY OF MAGNETIC RESONANCE IMAGING IN PERIANAL FISTULA
Objective: To evaluate the diagnostic accuracy of magnetic resonance Imaging in pre-operative evaluation of fistula-
Material and Methods: The study was conducted in the department of Radiology Khyber Teaching Hospital MTI
Peshawar from June, 2014 to June, 2016. A total of 50 patients with symptomatic fistula-in-ano referred for MRI pelvis
and meeting the inclusion criteria were included in the study. Informed consent was taken for MRI pelvis. All patients
had body coil MR Imaging examinations including the following sequences for anatomic and pathological information:
T2 sagittal, T1 axial oblique, T2 axial oblique, oblique axial and oblique coronal fat suppressed T1 with gadolinium
based contrast medium. Surgical findings were accepted as gold standard. MR Imaging findings were compared with
surgical findings using Park’s Classification and St. James University Hospital classification. The data were entered
and analysed into SPSS (version 21).
Results: In our study of 50 patients 44 patients were reported to have correct MRI assessment (88%) confirmed on
peroperative findings. 30 (68 %) cases had intersphincteric primary tract , 9 (20%) patients had trans sphinteric primary
tract, 4 cases(9%) suprasphincteric and 1(2.2%) had extrasphincteric primary tract according to Park’s classification.
Primary tracts were correctly identified in all patients. In 40 out of 44 patients internal opening were identified while
remaining 4 patients showed diffuse trans mural signal abnormality .In 35patients (80%) external opening were correctly
identified. 26 patients(60%) had low fistula in Ano, 11(26%) had high anal fistula and in 3 (6%) patients low rectal fistula
was identified.4 patients had complex fistula. The sensitivity, specificity, positive predictive value, negative predictive
value and accuracy were 91.6%, 85.7%, 97.7%, 60% and 90.9% respectively.
Conclusion: MR imaging provides precise definition of the fistulous track, along with its relationship to pelvic structures,
and allows identification of secondary fistulas or abscesses. Accordingly, MR imaging provides accurate information
for appropriate surgical treatment, decreasing the incidence of recurrence and allowing side effects such as fecal