P0254Evaluating the Magnetic Resonance Novel Index for Fistula Imaging and 3D volumetry for perianal Crohn’s disease: Reader agreement and disease severity

Abstract Background The Magnetic Resonance Novel Index for Fistula Imaging in Crohn’s Disease (MAGNIFI-CD)1,2 and 3D volumetry3 are emerging metrics for quantifying and visualizing perianal Crohn’s disease (pCD). This study evaluates inter-reader agreement for these metrics and examines their relationship to disease severity. Methods Fifty pelvic magnetic resonance imaging (MRI) examinations of 50 pCD patients were retrospectively selected from a single-centre hospital IBD database: 25 with minimal disease or fistula repair potential (TOpClass 1–2a) and 25 with symptom control or proctectomy as the clinical target (TOpClass 2b–3)4. Five abdominal radiologists and one senior radiology resident independently assessed each MRI using a commercial MAGNIFI-CD module (Entrolytics® by Motilent®), blinded to clinical data. The MAGNIFI-CD index (0–25) was recorded, and contrast-enhancing fistula volumes were manually segmented on axial post-contrast T1-weighted images (Figure 1). Inter-reader agreement was calculated using the intraclass correlation coefficient (ICC, two-way random-effects model). Group comparisons used t-test and Mann-Whitney U test. Results Overall inter-reader agreement was substantial for MAGNIFI-CD (ICC=0.75; 95% CI: 0.64–0.84) and almost perfect for 3D volume (ICC=0.89; 0.83–0.93). Agreement for MAGNIFI-CD was substantial in both TOpClass 1–2a, (ICC=0.71; 0.56–0.83) and in TOpClass 2b-3 (ICC=0.66; 0.48–0.82). Agreement for 3D volume was moderate (ICC=0.54; 0.37–0.72) in TOpClass 1–2a and almost perfect (ICC=0.89; 0.80–0.94) in TOpClass 2b–3. Mean MAGNIFI-CD score was higher in TOpClass 2b–3 (12,9 ± 4,5) than in TOpClass 1–2a (7,6 ± 4,2; p0.001). Median fistula volume was also greater in TOpClass 2b–3 (1911 mm³; IQR 921-3705) compared to TOpClass 1–2a (414 mm³; IQR 57–1109; p0.001). Conclusion MAGNIFI-CD and 3D volume measurements show substantial to almost perfect inter-reader agreement overall, supporting their reliability for clinical and research use. Agreement was moderate in mild disease, indicating greater assessment variability in this subgroup. Higher MAGNIFI-CD scores and larger fistula volumes were related to advanced TOpClass disease stages. References: 1. Hindryckx P, Jairath V, Zou G, et al. Development and Validation of a Magnetic Resonance Index for Assessing Fistulas in Patients With Crohn’s Disease. Gastroenterology. Nov 2019;157(5):1233–1244 e5. doi:10.1053/j.gastro.2019.07.0272. 2. Beek KJ, Mulders LGM, van Rijn KL, et al. External validation of the MAGNIFI-CD index in patients with complex perianal fistulising Crohn’s disease. European Radiology. 2024/08/30 2024;doi:10.1007/s00330-024-11029-33. 3. Caballol B, Ordás I, Saavedra C, et al. Volumetric Changes in Perianal Fistulizing Crohn’s Disease Measured by Magnetic Resonance Is Feasible and Could Be a Potential Biomarker to Predict Clinical Outcomes. United European Gastroenterol J. Jul 18 2025;doi:10.1002/ueg2.700034. 4. Geldof J, Iqbal N, LeBlanc JF, et al. Classifying perianal fistulising Crohn’s disease: an expert consensus to guide decision-making in daily practice and clinical trials. Lancet Gastroenterol Hepatol. Jun 2022;7(6):576–584. doi:10.1016/S2468-1253(22)00007-3. Conflict of interest: Johnson, Kristin: Consultant: Spago Nanomedical Speaker: Siemens Healthineers, Pfizer Shareholder: Sectra De Kock, Isabelle: Consultation fees from Motilent, Takeda, Alimentiv. Bengtsson, Johan: Consultant: Bayer Janssens, Birgitt: I do not have any conflict of interest to declare. Bislenghi, Gabriele: no conflict of interest Menys, Alex: CEO Motilent Associate Prof UCL Greer, Christian: Has been a paid contractor for Motilent Bhatnagar, Gauraang: Share options: Motilent Ltd. Fetch Health Radiology Lead: Motilent Central reader: Alimentiv Received payment for IBUS bootcamp Copenhagen, October 2025 funded by Helmsley. Verstockt, Bram: Research support from AbbVie, Biora Therapeutics, Celltrion, Landos, Pfizer, Sanofi, Sossei Heptares/Nxera and Takeda. Speaker’s fees from Abbvie, Agomab, Alfasigma, Biogen, Bristol Myers Squibb, Celltrion, Eli Lily, Falk, Ferring, Galapagos, Materia Prima, Johnson and Johnson, Pfizer, Sandoz, Takeda, Tillots Pharma, Truvion and Viatris. Consultancy fees from Abbvie, Alfasigma, Alimentiv, Anaptys Bio, Applied Strategic, Astrazeneca, Atheneum, BenevolentAI, Biora Therapeutics, Boxer Capital, Bristol Myers Squibb, Domain Therapeutics, Eli Lily, Galapagos, Guidepont, Landos, Merck, Mirador Therapeutics, Mylan, Nxera, Inotrem, Ipsos, Johnson and Johnson, Pfizer, Sandoz, Sanofi, Santa Ana Bio, Sapphire Therapeutics, Sosei Heptares, Takeda, Tillots Pharma and Viatris. Stock options Vagustim and Thethis Pharma.