Diffusion-weighted magnetic resonance for assessing fibrosis in Crohn's disease.

BACKGROUND: Intestinal fibrosis is a key feature of Crohn's Disease lesions, and mucosal biopsies do not exactly represent transmural damage. Magnetic resonance enterography (MRE) allows for a panoramic study of the bowel loops. Diffusion-weighted imaging (DWI) through the restriction of the apparent diffusion coefficient (ADC) allows for an accurate evaluation of disease activity in Crohn's Disease patients avoiding contrast agents. The aim of this study was to investigate whether DWI sequences were able to identify intestinal fibrosis in candidates for surgery, using histopathology as the gold standard. MATERIALS AND METHODS: Thirty Crohn's Disease patients undergoing surgery for stricturing ileo-colonic disease were consecutively enrolled from October 2010 to November 2015. All patients underwent MRE with DWI before surgery. Radiological parameters were calculated in the stenotic segment and in the ileum proximal to the stenosis. The histopathological examination was performed using a histological score for fibrosis and inflammation. RESULTS: ADC value correlated with the fibrosis score (r = -0.648; p < 0.0001), inflammation score (r = -0.763; p < 0.0001) and percentage of gain (r = -0.687; p < 0.0001). A correlation emerged between wall thickness and fibrosis score (r = 0.671; p < 0.0001). The threshold of wall thickness for fibrosis was > 6.3 mm (AUC 0.89, specificity 100% and sensitivity 69.23%). The cut-off of ADC value for fibrosis was < 1.1 × 10-3 mm2 s-1 with a sensitivity of 72% and specificity of 94% (AUC = 0.83). CONCLUSIONS: The DWI sequence with ADC value could be useful to identify fibrosis in the intestinal wall of Crohn's Disease patients.

Diffusion-weighted magnetic resonance for assessing ileal Crohn's disease activity.

BACKGROUND: Endoscopy and imaging objectively assess Crohn's disease (CD) activity. Magnetic resonance enterography (MRE) uses no ionizing radiation, carries no significant morbidity, and is highly sensitive in revealing soft tissues inflammation. Diffusion-weighted imaging can distinguish intestinal inflammation from a lower diffusion of water molecules giving rise to a reduced apparent diffusion coefficient. The magnetic resonance index of activity score and, more recently, the Clermont score were recently developed for staging CD activity. The aim of this study was to compare the MRE scores and the Simple Endoscopic Score for CD in identifying ileal CD activity. METHODS: Fifty-five patients with ileal and ileocolonic CD were consecutively enrolled between June 2012 and June 2013. All patients underwent clinical examination, biochemical tests, MRE, and colonoscopy to assess disease activity. RESULTS: MRE assessed active ileal disease in 31 patients (56.3%). The Clermont score significantly correlated with the magnetic resonance index of activity score (r = 0.91; P < 0.0001) and the Simple Endoscopic Score for CD (r = 0.76; P < 0.0001). The apparent diffusion coefficient correlated with the Simple Endoscopic Score for CD (r = -0.63; P < 0.0001) especially in unoperated patients. CONCLUSIONS: The Clermont score and the apparent diffusion coefficient value can stage ileal CD, avoiding the need to use contrast agents.