Bone flap perfusion assessment using near-infrared fluorescence imaging

Abstract

Background Microsurgical vascularized bone flaps are a versatile technique for reconstructing large bone defects. However, assessment of perfusion is challenging, as clinical examination is difficult intra-operatively and often not possible post-operatively. Therefore, it is important to develop techniques to assess perfusion of vascularized bone flaps, and potentially improve surgical outcomes. Near-infrared (NIR) fluorescence imaging has been previously shown to provide real-time, intra-operative evaluation of vascular perfusion. This pilot study investigates the ability of NIR imaging to assess perfusion of vascularized bone flaps. Materials and Methods Vascularized bone flaps were created on female Yorkshire pigs using well-established models for porcine forelimb osteomyocutaneous flap allotransplantation (N = 8) and hindlimb fibula flaps (N = 8). Imaging of the bone flaps was performed during harvest using the FLARE™ intraoperative fluorescence imaging system following systemic injection of indocyanine green (ICG). Perfusion was also assessed using standard of care by clinical observation and Doppler. NIR fluorescence perfusion assessment was confirmed by intermittent clamping of the vascular pedicle. Results NIR fluorescence imaging can identify bone perfusion at the cut end of the osteotomy site. When the vascular pedicle is clamped or ligated, NIR imaging demonstrates no fluorescence when injected with ICG. With clamp removal, the osteotomy site emits fluorescence indicating bone perfusion. Results using fluorescence imaging show 100% agreement with clinical observation and Doppler. Conclusion Vascularized bone transfers have become an important tool in reconstructive surgery; however, no established techniques adequately assess perfusion. Our pilot study indicates that NIR imaging can provide real-time, intra-operative assessment of bone perfusion.

Use of Intraoperative Fluorescent Angiography to Assess and Optimize Free Tissue Transfer in Head and Neck Reconstruction

“…To the authors' knowledge, this has not been described previously within human clinical models, but this concept has been proved within animal studies by Nguyen et al 30 The ability to objectively assess these tissue structures has clear ramifications in the design and harvest of the bone and composite flaps. The authors were able to better design their osteotomies when sectioning the fibula to create mandibular constructs.…”

Near‐infrared imaging for the assessment of anastomotic patency, thrombosis, and reperfusion in microsurgery: A pilot study in a porcine model

“…Our laboratory has previously demonstrated real‐time intraoperative NIR fluorescence angiography as a means of determining perforator location in addition to flap perfusion . NIR angiography has also been evaluated for the detection of flow changes following graded experimental arterial stenosis in a rodent model with encouraging results .…”

“…Collectively, these studies demonstrate the utility of NIR fluorescence as a comprehensive tool for guidance during tissue flap transplantation. Further study will be necessary to determine optimal use in evaluating other flaps, such as muscle; although pilot studies have examined use in vascularized bone flaps …”

Near-infrared imaging of face transplants: are both pedicles necessary?

“…Additionally, our group has demonstrated that NIR imaging can provide real-time, intraoperative assessment of bone perfusion. [30]…”