Detection of the fluorescence of GI vessels in rats using a CCD camera or a near-infrared video endoscope

Background: Choroidal near-infrared fluorescent angiography can detect vessels in the eye with high resolution. Observation of fluorescent gastrointestinal (GI) vessels by endoscopy may be useful in portal hypertension and bleeding ulcer. We here describe a technique for the detection of fluorescent GI vessels with a CCD camera or a near-infrared video endoscope. Methods: Laparotomy was performed on rats. A tissue target was excited by means of a laser diode. We took pictures of tissue under both white and near-infrared light, both before and after intravenous injection of indocyanine green. Fluorescent light was selected by means of filters placed in front of the lens of a CCD camera or a near-infrared video endoscope. Results: Under near-infrared light and after dye injection, we observed fluorescent vessels in real time and distinguished arterial from venous fluorescence. Conclusions: This device permits visualization of GI vessels, which could be useful for diagnosis of vascular abnormalities during endoscopy and surgery.