Recently, it has also been used in image-guided surgery studies to assess vessel patency after anastomoses in coronary artery bypass grafting (CABG 16) and to evaluate perforator location and flap perfusion in breast reconstructive surgery after mastectomy 17. ICG has been widely used in clinical applications such as liver function testing, cardiac output monitoring, and ophthalmic angiography. Pharmaceutical grade ICG was purchased from Akorn (Decatur, IL). We also sought to optimize the lymphatic tracer, injection site, dose, and timing for the intraoperative assessment of the thoracic duct. In this study, we hypothesized that these NIR imaging systems might provide adequate contrast for anatomical and functional assessment of thoracic duct after a simple subcutaneous injection. The enabling technology for our study is the Fluorescence-Assisted Resection and Exploration (FLARE) NIR optical imaging system, 15 which provides simultaneous acquisition of color video and two independent channels of invisible NIR fluorescence, one centered at 700 nm and the other at 800 nm, and the new, minimally invasive version of FLARE, the m-FLARE, for video-assisted thoracoscopic surgery (VATS). Intraoperative, real-time NIR fluorescence imaging has been used in many areas of surgery to visualize surgical anatomy and tissue function simultaneously and non-invasively with high spatial resolution. Indeed, thoracic duct NIR fluorescence imaging using ICG has been reported previously for the detection of chyle fistulae in the thoracic cavity. 11 Optical imaging using near-infrared (NIR) fluorescence has the potential to solve all of these problems (reviewed in 12, 13). Although oral administration of heavy cream before surgery is sometimes performed to visualize chylous leakage or to prevent injury to the thoracic duct, the contrast provided is low and identification of the thoracic duct can be difficult. In the past, blue dyes or indocyanine green (ICG) injections have been used, 8 – 10 as well as an invasive injection procedure in which popliteal lymph nodes, testicular parenchyma, or the mesenteric lymph duct are used as the injection site. 5 – 7 In addition, preoperative anatomical information is difficult to transfer directly to the intraoperative situation. 4Ĭurrently, lymphangiography and lymphoscintigraphy are available to preoperatively identify the site of thoracic duct damage however, these techniques do not permit precise localization of the injured site. Because traditional conservative treatment of thoracic duct injury has a high failure rate, 1 intraoperative image guidance is essential for proper surgical management. 1 – 3 Intraoperative identification of the thoracic duct can be difficult, especially during re-operation. Thoracic duct injury is a rare but serious complication following chest surgery and major neck dissections, with high mortality in untreated patients.
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