With this predominantly pictorial based overview, we aim to enlighten the reader about the differentfeatures of disease activity of Crohn's disease. The review focuses on small bowel Crohn's disease, as assessment of colonic disease ismostly endoscopic. We will briefly discuss the importance of accurate assessment of disease activity in Crohn’s disease and the increasingly important role MRI playsin this assessment. 1,2 With this poster we aim to: highlight what the clinician needs and wants to know from our Crohn's disease MRI reports. enable the reader...

In a stepwise approach,using examples from MRI small bowel studies as well as a review of the literature, we aim to demonstrate and discuss the common and validated key signs seen in the different stages of disease activity. These signs include layered/stratified enhancement, the comb sign, bowel wall oedema, restricted diffusion within the bowel wall and fibrotic strictures. 3,4 By using these key signs we have subdivided MRI-based disease activity into two groups, active and inactive disease. We also outline a simplified and structured approach...

The assessment of disease activity is complex, but vital for treatment planning and to guide the clinician in the use of immune-modulating, biologic andsurgical therapies.4,5 Assessing disease activity and severity remains difficult as there is a lot of overlap between stages of disease activity. Within individual patients, and even within lesions, active and inactive disease may co-exist. Accurate assessment requires a combination of clinical, biochemical, endoscopic, histological andradiological measures.5 There are numerous tools to assess the disease activity, including:Crohn’s disease activity index, faecal calprotectin,ileocolonoscopy, imaging,...

Small bowel MRI is an important and useful tool in assessing disease activity in patients with Crohn’s disease. Assessing disease activity can be complex and there is a lot of overlap between active and inactive disease, but when a simplified and structured approach is applied, using the key MRI findings we have illustrated, achieving an accurate assessment of Crohn's activity is significantly easier.

Evolving role of MRI in Crohn's disease. Yacoub JH, Obara P, Oto A et al. J Magn Reson Imaging. 2013 Jun;37(6):1277-89. Small bowel MR enterography:problem solving in Crohn’s disease. Griffin N, Grant LA, Anderson S et al. Insights Imaging. 2012 Jun;(3):251-63 Small-bowel MRI in children and young adults with Crohn disease: retrospective head-to-head comparison of contrast-enhanced and diffusion-weighted MRI. Neubauer H, Pabst T, Dick A et al. Pediatr Radiol. 2013 Jan;43(1):103-14 Mural inflammation in Crohn disease: location-matched histologic validation of MR imaging features. Punwani S,Rodriguez-Justo...