P130 A clear look into the bowel without cleaning it: simultaneous PET/MRI enterography (18F-FDG) for monitoring inflammatory activity in patients with ulcerative coliti—a prospective randomised controlled trial

Abstract

Introduction: The combination of positron emission tomography (PET) with 18Ffluorodeoxyglucose (18F‐FDG) with magnetic resonance imaging (MRI) as integrated PET/MR enterography in one examination is a new cutting‐edge technology for the non‐invasive assessment of the inflammatory activity in ulcerative colitis (UC). Regarding the diagnostic goldstandard procedure ileocolonoscopy beside the risk of injury especially the bowel purgation is rated most bothersome. Aims and Methods: This study's aim was to evaluate whether the inflammatory activity in patients with UC can be detected and accurately quantified by PET/ MRI with and without bowel purgation. Patients were randomized to simultaneous PET/MRI (index test) with or without bowel purgation 24h before ileocolonoscopy (reference standard). In every patient the maximum standardized uptake value ratio gut/liver (SUVQuot), an MRI index and an endoscopy index (EI; rated by 2 independent gastroenterologists) were calculated for every segment (ileum, caecum, ascending colon, transverse colon, descending colon, sigmoid colon and rectum). Sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy were calculated. Furthermore, receiver operating characteristic (ROC) curves for each colon segment were calculated to determine diagnostic accuracy of PET/MRI for the 2 modes of bowel purgation. Results: N=53 patients were included in the study. Ten patients were included for protocol optimization and 43 were randomized. Three patients were dropouts (two due to activity of disease other than UC, one refused endoscopy). Therefore, 19 patients (mean age=42.4 years (SD=11.71), 11 female (57.9%), mean time since diagnosis=13.42 years) were randomized to PET/MRI with bowel purgation and 21 patients (mean age=43.2 years (SD=12.7), 14 female (66.7%), mean time since diagnosis 12 years) to PET/MRI without bowel purgation. Sociodemographic and clinical characteristics did not differ between the groups. SUVQuot and EI correlated significantly for patients without bowel purgation (r=.53, p=.015) but not for those with bowel purgation (r=.46, p=.063). Overall sensitivity, specificity, positive predictive value, negative predictive value, and accuracy using ileocolonoscopy as reference standard are shown in table 1. ROC analyses for each bowel segment show that the diagnostic accuracy of PET was better for patients without bowel purgation (AUC rectum =.87, p=.03; AUC sigmoid colon=.91, p