Infrared endoscopy in the diagnosis and treatment of early gastric cancer

Infrared endoscopy combined with indocyanine green injection allows visualization of the vessels in the gastrointestinal tract. The depth of gastric cancer invasion has been diagnosed through evaluation of the submucosal vessels using this method. Small-scale retrospective studies have reported an accuracy for infrared endoscopy of >80% for the diagnosis of the depth of cancer invasion, regardless of ulcerative changes. This endoscopic technique should thus be considered as an additional diagnostic modality for determining the depth of gastric cancer, particularly in cases with ulcerative changes. However, the risk of a toxic reaction to indocyanine green must be addressed before the widespread use of infrared endoscopy can be implemented. Infrared fluorescence endoscopy utilizes the fluorescence of indocyanine green, and has been used not only for diagnosing the depth of gastric cancer invasion, but also for detecting neoplasia. Labeling and visualization of cancer in a resected specimen were possible following pre-treatment with anti-carcinoembryonic antigen antibody labeled with an indocyanine green derivative. A critical requirement for the detection of cancer using infrared fluorescence endoscopy is the identification of a safe labeling substance that attaches to the cancer with high affinity. It was possible to detect sites of bleeding during endoscopic resection of gastric cancers by submucosal injection or flushing of the bleeding site with indocyanine green solution. The dose of indocyanine green required by these methods is relatively low, and they can therefore be used to improve the safety of endoscopic resection with no increased risk of toxicity.