Tu1961 Inter- and Intra-Observer Variability for vs Classification Interpretation by Magnifying Endoscopy With Narrow Band Imaging in Assessment of Superficial Gastric Lesion

exposed to experimental models of colitis and sporadic or inflammation-associated tumor development and human tissue samples from patients with inflammatory bowel disease (Crohn's disease and ulcerative colitis) and sporadic colorectal cancer in comparison to control tissue. Tissue samples were obtained according to ethical guidelines and each patient gave written consent. Following preparation, fresh tissue samples were kept in PBS during multiphoton imaging. Excitation was performed at 800 nm and fluorescence and SHG were detected from 380 to 580 nm using a commercial MPM system. Results: Autofluorescence MPM of control tissue samples provided a detailed visualization of the mucosal layer with subcellular resolution and the possibility to discriminate individual structural components such as collagen filaments. Imaging of deeper tissue layers allowed the visualization of individual resident immune cells in the lamina propria of control tissues. MPM of inflamed murine or human colon tissues revealed a destruction of the mucosal epithelial layer and the crypt architecture together with a strong inflammatory cell infiltration of the lamina propria. MPM of colorectal cancer tissue allowed the visualization of histological characteristics of dysplastic tissue. Depending on the detection of different emission wavelengths, various aspects of tissue morphology could be highlighted (e.g. collagen filaments, infiltrating immune cells). Conclusion: Taken together, the results of this study clearly propose the usability of MPM based on the detection of autofluorescence for the evaluation of gastrointestinal disease. Therefore, the adoption of MPM for gastrointestinal endoscopy seems to be a feasible and attractive aim for the diagnosis of human disease.