Indocyanine Green Enhanced Endobronchial Ultrasound-Guided Transbronchial Laser Photoablation of Mediastinal Lymph Nodes.

SESSION TYPE: Thoracic Surgery IPRESENTED ON: Monday, October 22, 2012 at 11:15 AM - 12:30 PMPURPOSE: Endbronchial laser ablation is mainly used for treatment of endobronchial tumors. In this study, endobronchial ultrasound guided transbronchial needle aspiration (EBUS-TBNA) was utilized for ablative therapy for target lesions located in mediastinum. We examined the efficacy of indocyanine green (ICG) enhanced laser photoablation to lung cancer in both in-vitro and ex-vivo setting. The concept of EBUS-guided ICG injection / laser ablation was tested using in-vivo porcine model.METHODS: ICG enhanced laser photoablation (808 nm, < 250 mW) was performed in-vitro using cultured A549 lung cancer cells, and cytotoxic effect was assessed by MTS assay. Photoablation effect on human lung cancer tissue was examined using nude mouse orthotopic human lung cancer A549 Xenograft model in ex-vivo setting. EBUS guided ICG injection and laser photoablation was tested for the lymph nodes of a porcine model in in-vivo setting. The range of ablation in the treated lymph node was determined with NADH metabolic activity staining.RESULTS: ICG enhanced laser irradiation decreased the viability of A549 cancer cells down to 20% after 5 minutes of treatment. A549 orthotopic human lung cancer Xenograft tissue was heated up to 58 °C immediately when 50ul of ICG (0.25mg/ml) was locally injected and the laser was irradiated, and the ablated tissue was negative for NADH activity. In-vivo porcine model study revealed that EBUS guided ICG injection and laser irradiation (250 mW for 3 minutes ) ablated 8 x 6 mm of area of lymph node parenchyma, while the lymph node to which saline injected and laser irradiated did not show any histological changes.CONCLUSIONS: ICG enhanced laser photoablation exhibited sufficient cytotoxic effect in both in-vitro and ex-vivo settings. EBUS guided ICG injection and Laser photoablation successfully ablated mediastinal lymph node in a porcine model.CLINICAL IMPLICATIONS: The study allows further investigation for the development of ICG enhanced EBUS-TBN laser ablation therapy which may be applicable to localized mediastinal lymph node metastasis.DISCLOSURE: The following authors have nothing to disclose: Takashi Anayama, Takahiro Nakajima, Shaf Keshavjee, Kazuhiro YasufukuLab use laser generator and a fiber optics were used in the studyLatner Thoracic Surgery Research Laboratory, Division of Thoracic Surgery, Department of Surgery, Toronto General Hospital, University Health Network, Toronto, ON, Canada.