OP06. Endocytoscopy allows accurate in vivo differentiation of mucosal inflammatory cells in IBD – a pilot study

H. Neumann1, M. Vieth2, M. Grauer1, N. Thiem1, P. Schroll1, J. Mudter1, C. Günther1, M. Neurath1, R. Atreya1

1University of Erlangen-Nuremberg, Department of Medicine 1, Erlangen, Germany; 2Klinikum Bayreuth, Institute of Pathology, Bayreuth, Germany

Background: Precise activity assessment of inflammatory bowel disease (IBD) is essential to determine extent and severity of disease for optimized therapy. Nevertheless, despite ongoing developments in the field of gastrointestinal endoscopy, final diagnosis still relies on the interpretation of histopathological features of intestinal biopsies. Recently, endocytoscopy (EC) was introduced as a new endoscopic imaging modality, enabling in vivo microscopic imaging within the mucosal layer of the gut at a magnification level of up to 1400-fold. The aim of our study was to determine the reliability of EC for the discrimination of mucosal inflammatory cells and intestinal inflammatory disease activity in patients with IBD.

Methods: 40 patients with IBD (Crohn's disease n = 19; ulcerative colitis n = 21) who underwent colonoscopy were prospectively included in this study. Methylene blue or toluidine blue was topically applied to enable EC. Data were digitally saved and analyzed independently from each other by two gastroenterologists and one pathologist blinded to clinical and endoscopic data.

Results: EC enabled visualization of different histopathological features. Based on these specifications, it was possible to reliably distinguish single inflammatory cells by EC with the following sensitivities and specificities: neutrophilic (60% and 95%), basophilic (74.43% and 94.44%), eosinophilic granulocytes (75% and 90.48%) and lymphocytes (88.89% and 93.33%). Interobserver agreement between two investigators was substantial (Kappa 0.61–0.78) while intraobserver agreement was substantial for basophilic granulocytes (Kappa 0.76) and almost perfect for adjacent cell types (kappa 0.86–0.88). Concordance between EC and histopathology for grading intestinal disease activity was 100%.

Conclusions: EC enabled the detection and discrimination of single mucosal inflammatory cells and inflammatory disease activity. Therefore, this technique has the potential to improve both in vivo diagnosis and clinical management of IBD patients.