P273 Prediction of treatment response in Crohn's disease patients using contrast enhanced ultrasound: a pilot study

Abstract

Background: Increased vascularity of the bowel wall is an early pathologic change that occurs in patients with active Crohn's disease (CD) and is used in imaging methods with intravenous contrast. We investigated whether a baseline contrast-enhanced ultrasound (CEUS) can differentiate responders from non-responders treated medically over a period of 6 to 12 months. Methods: Unselected adult CD patients from a tertiary care IBD center were recruited. Baseline demographic and clinical data was gathered and CEUS was performed at baseline in patients using a second-generation US microbubble contrast agent (Definity®) using 0.2 ml as bolus followed by drip infusion at a fixed rate. Following placement of an ROI (region of interest) over the bowel wall, perfusion analysis software modeled time-intensity curves (TIC) and relative kinetic perfusion parameters were measured. In each patient, clinical activity, treatment and therapeutic outcome were assessed at 3, 6 and 12 months after the CEUS. Treatment changes after baseline, systemic steroid dependency, ongoing clinical activity, new disease complications and need for surgery during the observation period were considered treatment failures. CEUS parameters were compared in patients with active (aCD) versus inactive CD (aCD) at baseline and in patients with favorable versus poor outcome at 3, 6 and 12 months post CEUS. Results: Twenty-one patients (9 men, median age 32 years, median disease duration 13 years; 15 aCD and 12 with previous surgery) were recruited. Baseline kinetic CEUS parameters peak systolic velocity (PSV-wash in rate) & wash in/wash out area under curve (WiWoAUC) in bolus and drip infusion differed significantly in aCD (n=15) versus iCD patients (n=6), while there was no difference in bowel wall US features including peristalsis, vascularity, layers loss, submucosa echogenicity nor in CRP levels between the two groups (Table 2). At baseline, 8 patients were started on a new treatment or were escalated and 5 of them were non-responders at 6 months. There was a trend towards higher median values in baseline CEUS kinetic parameters (PSV and WiWoAUC) in responders versus non-responders (Table 2). Conclusions: CEUS is a potentially useful, non-invasive tool to identify patients with active CD and who are more likely to respond to therapy.