Burn depth estimation by use of indocyanine green fluorescence: initial human trial

Indocyanine green dye (ICG) fluoresces when illuminated by infrared light. After successful trials in a porcine model and with approval of the Massachusetts General Hospital's human studies committee, 10 adult patients with burn injuries were given 0.2 mg/kg ICG intravenously, and 825 nm fluorescence images were obtained with 780 nm excitation at 5 minutes after injection in the initial five patients and at 1, 2, 3, 4, 5, and 10 minutes in the subsequent five patients. Fluorescence intensities at burned and unburned sites were determined and images were correlated with burn depth as determined by healing or intraoperative assessment. In the latter five patients, seven sites were imaged (six that were of partial thickness and one that was of full thickness). The burn/normal skin fluorescence ratio was greater than 1 for superficial burns and less than 1 for deep burns. Imaging within 5 minutes of injection resulted in optimal contrast between injured and uninjured tissue. In this initial pilot trial it is apparent that ICG fluorescence has potential value as an aid in the early estimation of burn depth. In subsequent trials we will attempt to refine our ability to correlate ICG fluorescence images with burn depth.