Katsuichi Imaizumi

Reflected illumination-type imaging system for the development of infrared fluorescence endoscopy

Fluorescent labeled monoclonal antibodies against carcinoembryonic antigen (CEA) may provide a specific label for lesions of the GI tract. We previously developed an indocyanine green (ICG) derivative (ICG N‐hydroxy sulfo succinimide ester; ICG‐sulfo‐Osu) as a fluorescent label that is excited by infrared rays and is suitable for vital immunohistochemical staining. We also previously developed a transmitted illumination‐type (transmitted type) fluorescence imaging system that uses infrared rays to detect ICG‐sulfo‐Osu. In this paper we describe a new reflected illumination‐type (reflected type) imaging system for infrared fluorescence endoscopy. We tested the efficacy of this system on sections of human esophagus and normal skeletal muscle stained with ICG‐sulfo‐Osu labeled anti‐epithelial membrane antigen (EMA) antibody, and on sections of human gastric cancer tissue stained with ICG‐sulfo‐Osu labeled anti‐CEA antibody. Infrared fluorescent images were obtained with both fluorescent antibodies, and results correlated well with oxidized DAB‐positive sites. Vital immunohistochemical staining of micro cancers should be detectable by exciting an ICG‐sulfo‐Osu labeled antibody specific to the tumor cells with infrared rays, using this reflected type imaging system.