indocyanine green

Indocyanine green

Indocyanine green (ICG) is a cyanine dye used in medical diagnostics. It is used for determining cardiac output, hepatic function, liver and gastric blood flow, and for ophthalmic and cerebral angiography. It has a peak spectral absorption at about 800 nm. These infrared frequencies penetrate retinal layers, allowing ICG angiography to image deeper patterns of circulation than fluorescein angiography. ICG binds tightly to plasma proteins and becomes confined to the vascular system. ICG has a half-life of 150 to 180 seconds and is removed from circulation exclusively by the liver to bile. ICG is a fluorescent dye which is used in medicine as an indicator substance (e.g. for photometric hepatic function diagnostics and fluorescence angiography) in cardiac, circulatory, hepatic and ophthalmic conditions. It is administered intravenously and, depending on liver performance, is eliminated from the body with a half-life of about 3 to 4 minutes. ICG sodium salt is normally available in powder form and can be dissolved in various solvents; 5% (< 5% depending on batch) sodium iodide is usually added to ensure better solubility. The sterile lyophilisate of a water-ICG solution is approved in many European countries and the United States under the names ICG-Pulsion and IC-Green as a diagnostic for intravenous use.