Magnetic Resonance Imaging (MRI) Evaluation of Perianal Fistulae with Surgical Correlation

Abstract

Aims:The purpose of the study was to evaluate the role of Magnetic Resonance Imaging in detection and characterization of perianal fistulae and correlating it with surgical findings.Methods: Fifty consecutive patients with suspected perianal fistulae having one or more external openings were prospectively selected for MRI evaluation. Previously operated or patients with recurrent perianal disease were excluded from the study. MRI findings were recorded according to "St. James's University Hospital MR Imaging Classification of Perianal Fistulae" and correlated with surgical observations. Finally, comparison between T2-weighted fat saturated and postcontrast T1-weighted fat saturated sequences was done.Results: Amongst the total of 50 patients, per-operative findings confirmed perianal fistulae in 45 patients. The sensitivity and specificity of MRI in correctly detecting and grading the primary tract was found to be 95.56% and 80% respectively; for abscess, it was 87.50% and 95.24% respectively. High sensitivity was also discerned in identification of secondary tract (93.75%), correct localization of internal opening (95.83%) and for correctly detecting the horse-shoeing (87.50%). Our assumption of null hypothesis was accepted on comparing results of T2-weighted fat saturated sequences and postcontrast T1-weighted fat saturated sequences. Conclusion:Magnetic Resonance Imaging (MRI) was highly accurate in assessment of surgically important parameters (primary tract and its grading, internal opening, secondary tract, abscess, horseshoeing) of perianal fistulae. Comparison of results of imaging findings on T2-weighted and postcontrast T1-weighted fat saturated sequences were statistically similar, so contrast study can be omitted, particularly while evaluating primary / previously unoperated perianal fistulae.

Magnetic Resonance Imaging (MRI) Characterization of Perianal Fistulous Disease in a Rural Based Tertiary Hospital of North India

“…The results are in agreement with studies by Siddiqui et al, Singh et al and Becklingham et al who reported sensitivity of 95%, 95.5% and 97%, respectively [19–21]. PPV in our study is also comparable to a similar study by Singh et al who reported a PPV value of 97.7% in their study [20]. …”

MRI Enteroclysis and Enterography

“…In a recent study, Singh et al [16] stated that the contrast study can be omitted, particularly while evaluating primary/previously unoperated perianal fistulae because the results of imaging findings on T2-weighted and postcontrast T1-weighted fat saturated sequences were statistically similar. In our study, we focused on the role of STIR sequences in patients with CD in the diagnosis of perianal fistulas and in the evaluation of the extension of the inflammatory process in the perianal and perirectal areas, by comparing STIR and T1-images.…”

“…However, contrast medium is still used to assess perianal CD in different radiological centers as demonstrated by many studies [15][16][17]. Recent guidelines reported the usefulness of gadolinium-enhanced T1-weighted sequence for the differentiation between fluid/pus and granulation tissue [18].…”

“…The site of abnormality was classified radially around a clock face, with the patient in the lithotomy position. Fistulas were classified according to the Parks' criteria [16] as follows: superficial (a), inter-(b), trans-(c), supra-(d) or extra-(e) sphincteric. Patients were also classified as having simple fistulas or complex perianal disease.…”

Perianal Fistüllerde MR Görüntüleme

“…Fistül saptanmasında postkontrast yağ baskılı T1 (T1 YB) görüntüler de T2 ağırlıklı görüntüler kadar başarılıdır [22]. Pek çok merkezde olduğu gibi bizim birimimizde de postkontrast T1 YB görüntüler T2 görün-tülerle birlikte alınmaktadır.…”