Purpose

Magnetic Resonance Imaging (MRI) is the reference standard for determining the extent of perianal fistulising Crohn’s disease (pCD), for which the original van Assche (VA) and recently the modified van Assche (mVA) and MAGNIFI-CD indices can be used. These three scores were compared in a hyperbaric oxygen therapy trial (HBO).

Material and methods

17 patients with therapy-refractory pCD were treated with 40 HBO sessions. Co-primary outcomes were clinical response (perianal disease activity index, PDAI) and MRI (sagittal/coronal/transversal T2, transversal FST2, transversal CE-FST1) improvement, 2 months after HBO as compared to baseline MRI.

Results

17 patients (6 female, median age 34 years) were treated; thirteen had complex transsphincteric fistulae, 7 supralevatoric extension. Inflammatory mass was present in 13, including 1 small and 2 medium collections. Most tracts were predominantly filled with granulation tissue (14 patients), and 3 with fluid/pus. 10 patients had rectal wall involvement.

Median scores for PDAI decreased from 8 (95%CI 6-10) at baseline to 4 (95%CI 3-6) at follow-up (p<0.001). Median scores for the VA index decreased from 13 (95%CI 11-16) to 12 (95%CI 10-13)(p=0.017), mvA index from 9.4 (95%CI 7-11.2) tot 7.3 (95%CI 6.9-10)(p=0.001) and MAGNIFI-CD from 16 (95%CI 13-19) to 14 (95%CI 13-16)(p=0.003).

Items that were most subject to change were inflammatory mass, rectal wall involvement and dominant feature of the primary tract (fluid/pus; granulation tissue; fibrosis).

Conclusion

All three MRI indices showed significant improvement after treatment with HBO. Inflammatory items as well as the dominant feature of the primary tract were responsive to hyperbaric treatment.