3437 Dynamic holographic endoscopy - pilot investigations using an in-vitro model.

Abstract

The combination of holographic interferometric metrology and endoscopic imaging can be applied to assess disturbances of gastrointestinal wall elasticity. Connecting an Electronic Speckle Pattern Interferometry (ESPI) camera system with a continuous wave Argon-ion laser (λ=514,5 nm) as its light source to a standard fiber glass gastroscope, we performed in-vitro experiments on porcine stomachs to detect areas characterized by altered tissue elasticity. Linking the endoscopic ESPI camera system to a fast image processing system, we were able to apply the method of double pulse exposure image subtraction at a video frame rate of 12,5 Hz. In a series of experiments, we analysed the speckle correlation patterns resulting from gastric wall deformation induced by gentle touch with a guidewire. Interferograms of gastric wall areas without structural abnormalities showed concentric fringes, the center of which corresponding to the point of stimulation. In contrast to that, fringe patterns that corresponded to areas of reduced tissue elasticity, as produced by implanting foreign materials (e.g., tissue glue) into the muscularis propria layer, were characterized by parallel lines, indicating that stimulation primarily led to tilting. We conclude that gastric wall abnormalities leading to altered tissue elasticity (but not necessarily producing visible changes on the mucosal surface) can be demonstrated by applying the method of dynamic holographic endoscopy.