An endoscopic approach providing near-infrared laser-induced coagulation with accurate depth limits

Abstract

This article investigates an endoscopic approach that utilizes negative pressure to achieve laser-induced thermal coagulation limited to the esophageal wall's mucosal and superficial submucosal layers. The study was built upon a series of studies combining numerical simulation based on the Monte-Carlo technique and ex vivo porcine tissue experiments, including apparatus design and histology analysis. An endoscopy apparatus was developed using 3D printing to validate the tissue stretching-based approach. A fiber-pigtailed diode was used as the near-infrared source, emitting 208.8 W/cm² laser irradiance at 1.5 μm. Simulation results suggested that the approach successfully created a local heat well to prevent residual thermal effects (>65°C) from penetrating the deeper submucosal layer. Histology analysis of ex vivo tissues showed that at a fluence of 5.22 kJ/cm², the depth of thermal coagulation was reduced by half compared to the control. With further preclinical studies, including endoscopy apparatus design, the approach can be applied to the larger esophageal surface.