Contrast-Enhancing Optical Probe for Near-Infrared Fluorescence Imaging Under Surgical Light Illumination

Guided surgery often encounters signal saturation and noise, due to strong illumination from the surgical light. The current study developed a customized optical probe filtering incident wavelengths of ≥800 nm to selectively detect near-infrared (NIR) fluorescence signals under strong illumination. The feasibility of the fabricated filter for fluorescence imaging was evaluated with tubes containing indocyanine green (ICG) and lymph nodes in vivo mouse models. The fluorescent images were acquired under three different conditions for comparison: dark room (DR), conventional surgical light (CSL), and filter-assisted surgical light (FSL). ICG at the concentration of 0.7 μg/ml yielded the highest signal intensity Both DR and FSL yielded higher image contrasts (87.3% and 82.6%) compared to CSL (67.0%). The in vivo results confirmed that the proposed optical probe enhanced the image contrast of the lymph nodes in mice by three-fold (i.e., 16.7±4.4% for CSL vs. 55.6±5.0% for FSL; p < 0.05). However, the condition involving DR (68.5±2.4%) continued to generate a slightly higher image contrast compared to that involving FSL. Thus, we can effectively use the NIR fluorescence imaging system simultaneously in the improved surgical light source by the proposed method.