The Optical Properties of Indocyanine Green suspended in Solution as Observed under Near Infrared LED and LASER Light Conditions

The use of Indocyanine Green (ICG) as a fluorescent marker at Near Infrared (NIR) excitation wavelengths is well established in clinical imaging. Typical systems comprise multiple LED sources for optimal imaging which can result in unnecessary energy transfer to patients and contribute to tissue damage. An experimental setup comprising a 780 nm excitation channel generating up to 10 mW of optical power is used in order to determine if there is potential to exploit the optical properties of ICG, in order to reduce the total excitation power through pulsing. We demonstrate in this work that a single 1.6 Megapixel CMOS camera with quantum efficiency of less than 30% is appropriate to capture both fluorescent and non-fluorescent landmarks at NIR wavelengths. Experimental results verify that all ICG solutions tested yielded detectable fluorescence and that degradation of fluorescence intensity over time is multifaceted.