Abstract: ObjectiveTo explore the clinical value of different MR sequences in diagnosis of perianal fistula. MethodsMRI was performed on fifteen cases of clinically suspected as perianal fistula. The MR pulse sequences included sagittal T₂ WI (SAG T₂ WI), coronal T₂ WI with fat suppression (COR T₂ FS)， axial T₁WI(AX T₁WI), axial T₂WI(AX T₂WI), axial T₂WI with fat suppression(AX T₂ FS) and dynamic contrast enhancement(DCE). The MR findings were compared with the surgical results. Results16 internal opening and 14 tracks were found in 15 cases. Based on John Morris′s study, 3 cases were grade1, 6 cases were grade2, 3 cases were grade3, 2 cases were grade 4, and 1 case was grade 5. 2 cases only had perianal abscess. The internal opening display rate of the DCE imaging was much higher than that of other sequences, but there were no statistical differences between the DCE and AX T2 FS（P＞0.05）. The fistula track display rate of the DCE imaging was also much higher than that of the other sequences, and there were statistical differences only between the DCE and AX T1WI（P＜0.05). ConclusionOptimized coronal T2 fat suppression and dynamic contrast enhanced MR imaging are critical for perianal fistula, which provides great help for surgical planning and treatment.

Key words: Magnetic resonance imaging, Perianal fistula