Using MRI to guide surgical strategy for perianal fistulas: from conventional acquisition to 3D modeling.

Magnetic resonance imaging (MRI) is the gold-standard imaging modality for evaluating perianal fistulas, playing a pivotal role in characterizing fistula anatomy and guiding optimal surgical strategies. Appropriate preoperative MRI assessment can significantly reduce recurrence rates and minimize the risk of complications, such as fecal incontinence. This article reviews the most relevant information that an MRI report should contain to aid effective surgical decision-making for perianal fistulas. These features influence therapeutic choices, including decisions regarding the suitability of techniques like fistulotomy, ligation of the intersphincteric fistula tract (LIFT), video-assisted anal fistula treatment (VAAFT), fistula-tract laser closure (FiLaC), and advancement flaps. The emerging role of three-dimensional (3D) modeling from MRI data is also discussed, highlighting its potential to enhance surgeons' spatial understanding of complex fistulous anatomy, thereby improving surgical planning, reducing operative time, and ultimately improving outcomes. However, the generation of accurate 3D models depends on meticulous image segmentation and interpretation by experienced radiologists. Future research directions, including the integration of 3D models with intraoperative navigation and standardized assessment of inflammatory activity, are also addressed in this review.