Fig. 1

Exemplary images for the image evaluation in each of T2W and DWI images. a Score 2 in both T2W and DWI as the fistula is well visualized in both images. b Score 2 in T2W and score 1 in DWI, as the fistula was well visualized in T2W and suboptimally visualized in DWI (yellow arrows). Another fistula was scored 2 in both images (red arrow). C) Score 0 in both T2W and DWI as no fistula could be seen in either images. This T2W image (C) is only a representative image from another patient, without perianal fistula