Near-infrared fluorescence angiography with Indocyangreen (NIRF)
Near-infrared fluorescence angiography (NIRF) provides real-time visualization of vessel structure during surgical procedures. This uses near-infrared fluorescence technology to visualize detailed information about the blood vessels. This is done by injecting a dye -mostly- indocyanine green (ICG) intravenously - binding to albumin in the plasma [67] and capturing images with near-infrared light. NIRF delivers intraoperative visualization of vascular structures, leveraging advanced near-infrared fluorescence technology. By intravenously administering indocyanine green (ICG), NIRF enables real-time imaging of intricate blood vessel networks, as meticulously detailed in the Meta-analysis conducted by Smit et al. This timeframe varies between 12 and 27 seconds. [68]
Depending on the available system, a movable arm allows flexible positioning of light sources and optics over the surgical area. The captured images can be displayed either as still images or as movies on monitors. This technique has proven successful in both preclinical research and clinical applications from vascular surgery over Plastic surgery [67] to breast reconstruction after mastectomy. [69] Perfusion patterns visualized with NIRF imaging are quantified using time-intensity curves, providing various parameters for statistical analysis and visualization. These parameters, including Ingress, Egress, Fluorescence intensity, Tmax, T1/2, and others, allow for standardized quantification of tissue perfusion using NIRF imaging, aiding in clinical decision-making and optimizing surgical outcomes. [67]
It can also be used to assess tissue flap perfusion during surgical planning in the location of perforators to predict tissue flap survival and reduce the risk of necrosis areas. [69-72] As described in the study by Lee et al, near-infrared fluorescence angiography enables real-time visualization of vessel structure intraoperatively. Near-infrared fluorescence angiography can be used in the course of flap planning of perforating vessels and a study by Matsiu et al was able to predict the survival of submental flaps via ICG injections at 0, 0.5, 24, 48, and 72 hours postoperatively via the percentage area of vital perfusing flap areas and predict necrosis areas after 72 hours. [72] In a study by Lohman et al, the above technology application had a high sensitivity of 90 per cent in intraoperative flap planning in terms of blood flow indication. [73] Furthermore, as described by Ludolph et al, this technique can be a viable tool for perfusion monitoring over longer periods and can be used to evaluate free flap-Autonomization. [21]