A pictorial review of the impact of adding diffusion-weighted MR imaging to other MR sequences for assessment of anal fistulae.

The purpose of this article was to review the utility of diffusion-weighted MR imaging (DWI) findings in anal fistulae compared to other sequences, and to become familiar with the wide variety of DWI findings of this entity. DWI is useful for evaluating anal fistulae because it makes it possible to detect small lesions and many lesions at the same time, show the spread of the lesions, and assess the degree of inflammation, and it can be useful when following up anal fistulae.