Study on the vascular structure of esophagial varices using infrared fluorescent endoscopy

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Several studies reported that infrared endscopy (IRE) is useful for examining esophageal varices. Although infrared fluorescence has been used in the field of ophthalmology and dermatology, it has not yet been used in endoscopy for the digestive tracts. Using infrared fluorescent endoscopy (IRFE) developed by Ito et al., the present study evaluated the detectability of esophageal varices. The subjects were 12 patients with esophageal varices. The postoperative course of these patients were followed after the treatment by endoscopic variceal ligation (EVL) or endoscopic injection sclerotherapy (EIS). ICG was administered intravenously at k different doses (2 mg/kg, 0.2 mg/kg, or 0.01 mg/kg), and infrared fluorescent images were acquired. The entire esophageal mucosae were visualized by strong white infrared fluorescence in 2 patients treated with 2 mg/kg of ICG and in 2 patients treated with 0.2 mg/kg of ICG. Therefore, the discrimination of esophageal varices from the normal mucosae was difficult in these patients. Infrared fluorescence corresponding to the esophageal varices observed by conventional endoscopy was clearly observed in 7 patients treated with 0.01 mg/kg of ICG. IRFE facilitated the visualization of microvessels after endoscopic treatment of esopliageal varices. In addition, tissues other than blood vessels did not show infrared fluorescence. Compared to conventional IRE, IRFE facilitated the observation of esophageal varices after intravenously injecting a markedly small amount of ICG. Therefore, IRFE may be useful for preventing ICG-induced complications. In the future, due to its higher sensitivity and specificity, IRFE may be used in the diagnosis of vascular lesious in the digestive tract as a novel diagnostic endoscopy.