Fluorescence guidance systems are used for different indications, and the relevant range of concentrations and the relevant dye used varies considerably for human clinical trials. Most systems are designed for high concentration ICG imaging, where 0.1 mg/kg is injected IV and perfusion is imaged, yet other applications such as delayed uptake (or second temporal window) ICG imaging can have tissue concentrations an order of magnitude or more below this. Additionally, IRDye800 is used in both antibody imaging and small protein imaging in clinical trials, but injected doses vary from therapeutic to microdose levels. In this study, the sensitivity to both perfusion dose and microdose ranges were tested for ICG and IRDye800CW, using the Spy Elite system (Stryker) and the Solaris (Perkin Elmer). The sensitivity to ICG was significantly different and the sensitivity to IRDye800 was also different but with opposite choice of the optimal system. The concentrations tested ranged from 0.1 mg/kg down to 0.1 ug/kg. The signal to background limited the sensitivity in both cases, and the ambient light effects were significantly different in the two systems. The in vivo testing in lymphatic and vascular transport was assessed to determine limits to detection for vessel size.
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