419 Endoscopic Visualization of the Submucosal and Myenteric Neuronal Network of the GI Tract Using EUS-Guided Needle Based Confocal LASER Induced Endomicroscopy: Exploring the New Blue Ocean of the Submucosal Space

419 Endoscopic Visualization of the Submucosal and Myenteric Neuronal Network of the GI Tract Using EUS-Guided Needle Based Confocal LASER Induced Endomicroscopy: Exploring the New Blue Ocean of the Submucosal Space Jason B. Samarasena*, Andrzej S. Tarnawski, Susumu Shinoura, Amrita Ahluwalia, John G. Lee, Kee Don Choi, Kenneth J. Chang Gastroenterology, Univ of California Irvine, Orange, CA; Long Beach VA Healthcare System, LONG BEACH, CA Background: Confocal laser induced endomicroscopy (CLE) is a novel tool that enables in-vivo histologic imaging by detection of fluorescence. Using probebased CLE, in-vivo imaging of the neural network of the muscularis propria (MP) of the porcine esophagus has been recently described. Access to the MP was achieved via a technically challenging submucosal tunneling technique. Recently, an ultrathin CLE catheter probe has been developed which inserts into a standard 19G needle and allows for endoscopic ultrasound guided needle-based CLE (nCLE), thus providing the opportunity for less invasive imaging of submucosal and myenteric structures. Aims: To determine the feasibility of invivo visualization of the submucosal and myenteric neural network in the porcine esophagus, stomach and duodenum using EUS guided nCLE with local injection of a fluorescent neuronal molecular probe Neurotrace®. Materials And Methods: Studies were performed in 4 anesthetized pigs. Mid and distal (near lower esophageal sphincter) esophageal sites, proximal and distal stomach sites, and duodenum were evaluated in each pig. At each site, Neurotrace was injected via EUS-guided 19G FNA needle at the submucosa-muscularis propria interface. The nCLE probe (Cellvizio AQ-Flex-19, Mauna Kea Technologies, Paris, France) was then introduced to the site and nCLE imaging performed with time to identification of neuronal structures and quality of images recorded. After obtaining CLE images, pigs were euthanized and esophagus, stomach and duodenum sites injected with NeuroTrace were obtained for histologic examination and molecular imaging with HuC antigen, a specific neuronal marker to further characterize and independently validate nCLE findings. Results: EUS-guided nCLE was successful in accessing the esophageal deep submucosa and MP for imaging in all 4 animals. In 30secs 2min after Neurotrace injection, nCLE clearly visualized submucosal and myenteric neural structures at all sites. Imaging quality of neuronal structures in the esophagus, stomach and duodenum was excellent. EUS injected NeuroTrace was visible in histologic sections under fluorescent microscopy and was localized to neural structures confirming nCLE findings. Immunohistochemical staining with HuC antibody showed expression and distribution in the neuronal ganglia and nerves that was similar to that of Neurotrace, thereby confirming in-vivo nCLE imaging. Conclusions: EUS-guided nCLE following local injection of Neurotrace successfully allowed for in-vivo imaging of the myenteric and submucosal neural network without the need for submucosal tunneling or resection. Endoscopic access into the submucosal space with interrogation of the neural network has the potential to provide new insights into a wide spectrum of motility disorders of the GI tract.