Defining Radiological Healing in Perianal Fistulizing Crohn's Disease: a TOpClass Global Expert Delphi Consensus

Easan Anand; Jalpa Devi; David H Ballard; Shivani Joshi; Phil Tozer; Ailsa Hart; Anna Antoniou; Parakkal Deepak; Jaap Stoker; Phillip Lung; TOpClass collaborative authors

doi:10.1016/j.cgh.2025.02.009

Defining Radiological Healing in Perianal Fistulizing Crohn's Disease: a TOpClass Global Expert Delphi Consensus

Clin Gastroenterol Hepatol. 2025 Apr 8:S1542-3565(25)00248-4. doi: 10.1016/j.cgh.2025.02.009. Online ahead of print.

Authors

Collaborators

TOpClass collaborative authors:
Vineet Ahuja, Emre Altinmakas, Sulak Anandabaskaran, David H Ballard, Rupa Banerjee, Corina Behrenbruch, Willem Bemelman, Elena Bermejo, Gauraang Bhatnagar, Gabriele Bislenghi, Cristiana Bonifacio, Christianne Buskens, Bénédicte Caron, Michele Carvello, María José Casanova, Ben Cohen, Susan Connor, Andre D'Hoore, Bari Dane, Silvio Danese, Isabelle De Kock, Vincent de Parades, Parakkal Deepak, Anders Dige, Jonathan Dillman, Nik Ding, Michael Eberhardson, Nadia Fathallah, Joel Fletcher, José Carlos Garcia-Gil, Krisztina Gecse, Jeroen Geldof, Mary-Louise Greer, Arun Gupta, Steve Halligan, Carla Harmath, Ailsa Hart, Stefan Holubar, Karin Horsthuis, Chenchan Huang, Nusrat Iqbal, Sergey Khaitov, Paulo Kotze, Andrea Laghi, Jean-Frederic LeBlanc, Amy Lightner, Triana Lobaton, Lilli Lundby, Phillip Lung, Francesca Maccioni, Jeffrey McCurdy, Benjamin McDonald, Gordon Moran, Pär Myrelid, Anne Negård, Siew Ng, Pasquale Paolantonio, Alyssa Parian, Bodil Ginnerup Pedersen, Andrew Plumb, Nick Powell, Natalia Queiroz, Jordi Rimola, Pablo Rodríguez Carnero, David Rubin, Kapil Sahnan, Martina Scharitzer, David Schwartz, Melanie Seale, Shaji Sebastian, Vishal Sharma, Ajit Sood, Antonino Spinelli, Jaap Stoker, Stuart Taylor, Jeroen Tielbeek, Phil Tozer, Dirk Van de Putte, Bram Verstockt, Janindra Warusavitarne, Leon Shin-Han Winata, Serre-Yu Wong, Guy Worley

Affiliations

¹ Department of Surgery & Cancer, Imperial College London, London, United Kingdom; Robin Phillips Fistula Research Unit, St Mark's the National Bowel Hospital, London, United Kingdom. Electronic address: era24@ic.ac.uk.
² Division of Gastroenterology, Washington University School of Medicine in St Louis, St Louis, Missouri.
³ Department of Surgery & Cancer, Imperial College London, London, United Kingdom; Robin Phillips Fistula Research Unit, St Mark's the National Bowel Hospital, London, United Kingdom.
⁴ Robin Phillips Fistula Research Unit, St Mark's the National Bowel Hospital, London, United Kingdom.
⁵ Radiology and Nuclear Medicine, Amsterdam University Medical Centre, University of Amsterdam, Amsterdam, The Netherlands.
⁶ Department of Surgery & Cancer, Imperial College London, London, United Kingdom; Robin Phillips Fistula Research Unit, St Mark's the National Bowel Hospital, London, United Kingdom. Electronic address: philliplung@nhs.net.

PMID: 40210078
DOI: 10.1016/j.cgh.2025.02.009

Abstract

Background & aims: Perianal fistulising Crohn's disease (pfCD) affects one-fifth of patients with Crohn's disease (CD), significantly affecting their quality of life. Magnetic resonance imaging is the gold standard for evaluating fistula healing in pfCD, but variability in radiological definitions hampers meaningful clinical interpretation and consistent trial design. This study aimed to establish an international consensus on the definition of radiological healing in pfCD.

Methods: The study was conducted in 2 phases. Phase 1 involved a systematic review to identify magnetic resonance imaging-based variables and indices used to define healing in pfCD, assessing methodological quality using the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) framework. Phase 2 utilized a 2-round online Delphi consensus process with 84 international experts, followed by a stakeholder meeting to achieve consensus (agreement threshold >80%). Results were reported as per Accurate Consensus Reporting Document (ACCORD) guidelines.

Results: A radiologically healed fistula can be defined by the absence of T2-weighted hyperintensity, a completely fibrotic fistula tract and, when contrast is used, the absence of contrast enhancement on post-contrast T1-weighted images (95% consensus). Radiological improvement of a fistula can be defined (80% consensus) by the presence of a least one essential criterion: an increasingly fibrotic fistula tract, an unequivocal reduction in one or more of the following: T2-weighted hyperintensity, fistula diameter, fistula length, abscess size, or contrast enhancement of the fistula tract.

Conclusion: This international Delphi consensus standardizes radiological endpoints in pfCD, improving consistency in clinical and research settings. Future studies will validate this definition and assess how radiological changes predict long-term clinical outcomes and quality of life improvements.

Keywords: Endpoints; Fistula; Healing; MRI; Perianal Fistulising Crohn’s Disease.