Abstract:

Aim: The aim of this study was to evaluate the role of diffusion-weighted magnetic resonance imaging (MRI) in assessing the activity of perianal fistulae. Method: This retrospective, cross-sectional study included 30 patients with perianal fistula. MRI with diffusion-weighted imaging (DWI) was performed with 1.5 T-scanner. The MRI findings were correlated with local clinical examination and or postoperative findings as reference. Results: A total of 42 perianal fistulae in 30 patients were identified. The detection rate of perianal fistula by DWI was less than by T2-weighted (T2W) and combined DWI-T2W imaging. Thirty-three perianal fistulae (76.2%) were clearly diagnosed in 42 fistulae on DWI, 40 (88.1%) on T2W, and 41 fistulae (95.2%) on DWI-T2W images. The mean of apparent diffusion coefficient (ADC) values was significantly different between active fistulae at 0.919±0.165 x10-3 mm2/s and inactive fistulae at 1.235±0.220 x10-3 mm2/s (p<0.0035). A cut-off mean ADC value of 1.005 x10-3 mm2/s was used to differentiate active from inactive fistula with a sensitivity of 84% and a specificity of 71.5%. Conclusion: These results showed that the ADCs measured from active and inactive perianal fistulae differ significantly in patients who were on an antibiotic treatment. Therefore, DWI may be used to evaluate the activity of a perianal fistula and identify patients with a higher likelihood of recurrence.

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