Effectiveness of the near-infrared electronic endoscope for diagnosis of the depth of involvement of gastric cancers

Background: Near-infrared light penetrates deeply into tissue but is not visible with a conventional endoscope, We developed a new infrared electronic endoscope system and evaluated its usefulness for assessing the depth of involvement of gastric cancers. Methods: A total of 61 patients with depressed or ulcerated gastric cancers underwent infrared endoscopy after intravenous injection of indocyanine green. Results: Intramucosal cancers were observed as tumors with or without a homogeneous tumor stain, whereas submucosal or deeper cancers were observed as tumors with an inhomogeneous stain or with pooling of the dye. Histologic examination showed staining properties of gastric cancers were significantly correlated with the characteristics of the vascular bed. The accuracy for depth of cancer invasion was 89% for mucosal cancers and 89% for submucosal or deeper cancers. Conclusion: Our new infrared electronic endoscope system was useful for distinguishing mucosal cancers from submucosal or deeper cancers either with or without ulcerative changes.