The lymphatic system plays a crucial role in the spread of solid tumors and is often the first site of metastasis, as cancer cells typically invade nearby lymph nodes (LN) before potentially spreading to other LNs through the lymphatic system and distant organs through the bloodstream

Background: Fracture non-union cause chronic pain, dysfunction, and high healthcare costs. Treatment consists of revitalizing the nonhealed fracture site through debridement, bone resection, grafting, or stabilization if indicated. Adequate bone perfusion is essential for healing, but current intraoperative assessments are subjective. This study explores the feasibility of using quantitative near-infrared fluorescence (NIRF) imaging with indocyanine green (ICG) to assess bone perfusion in non-union surgery. This technique allows real-time visualization of tissue perfusion through tracing intravascular injected ICG. Methods: This prospective, multicenter feasibility study was conducted in 2 Dutch academic hospitals. Intraoperative ICG NIRF imaging was performed in non-union patients after debridement and before osteosynthesis. Time-intensity curves were derived from intraoperative data, and 3 time-related perfusion parameters were extracted to quantify the perfusion in various osseous structures. Demographic data included patient's age, sex, race, and body mass index. Results: ICG NIRF measurement was successfully performed in 20 patients (median age 50.5 years, 65% female, and 90% White) at 7 fracture locations. Three distinct perfusion patterns were observed. (1) rapid ingress and egress, (2) rapid ingress with a plateau phase, and (3) prolonged ingress with no egress within the measurement. The median Tmax was 214 s (inter-quartile range [IQR]): 69-246 s. The normalized maximum ingress slope was 4.4%/s (IQR: 2.4-6.5), and the median Egress-60 was 84.7% (IQR: 77.4-94.8). Conclusion: ICG NIRF imaging is a feasible and reproducible method for intraoperative bone perfusion assessment in fracture non-union, potentially offering an objective measure of bone vitality. Perfusion parameters and time-intensity curves were successfully quantified across various bone structures, revealing patterns similar to those linked with clinical outcomes in other studies. Future research should evaluate how these perfusion patterns relate to bone healing. Level of Evidence: Level II . See Instructions for Authors for a complete description of levels of evidence.