Magnetic resonance imaging after ligation of the intersphincteric fistula tract for high perianal fistulas in Crohn's disease: a retrospective cohort study

Aim: Ligation of the intersphincteric fistula tract (LIFT) is increasingly being used for surgical closure of high perianal fistulas in Crohn’s disease. Currently, data on postoperative MRI findings are scarce, although they are considered important for assessing healing and recurrence. Our aim, therefore, was to evaluate fistula characteristics on MRI and their relationship with clinical outcomes after LIFT. Method: Consecutive Crohn's patients treated with LIFT between 2007 and 2018 who underwent baseline and follow-up MRI were retrospectively included. MRIs were scored by two radiologists according to characteristics based on the original and modified Van Assche indices. MRI findings, with emphasis on fibrosis, and the relationship with clinical healing, re-interventions and recurrences are described. Results: Twelve patients were included [four men, median age 34 (interquartile range 28–39) years]. Follow-up MRI was performed at a median of 5.5 months (interquartile range 2.5–6.0) after LIFT. At baseline, all patients showed a tract with predominantly granulation tissue, which changed to predominantly fibrotic in seven (in three of whom it was completely fibrotic). All patients with a (predominantly) fibrotic tract had clinical closure and no re-interventions or recurrences during long-term follow-up. In contrast, of the five patients with persisting granulation tissue, two reached clinical healing, two needed re-intervention and one had a recurrence. Conclusion: Markedly decreased fistula activity can be observed on MRI after LIFT. The majority of patients develop a predominantly fibrotic tract relatively soon after LIFT without clinical recurrence, suggesting a highly effective therapy. Unfavourable clinical outcomes were only present in patients with persisting granulation tissue, indicating the potential prognostic value of MRI