(P 515) ENDOBRONCHIAL NAVIGATION AS AN INTRAOPERATORY TOOL FOR RESECTION OF SMALL PULMONARY METASTASES IN SARCOMA PATIENTS

Objective: To describe our new approach combining intraoperatively electromagnetic navigation bronchoscopy (ENB) with pleural dye marking and/or technetium99-macroaggregated albumin (99mTC-MAA) administration in a series of pulmonary nodules thoracoscopically resected.

Methods: A first phase of planning was developed by reconstruction of a computed tomography (CT) (thickness of 1-1.25 mm; overlap 20-50%) with the Illumisite© version 7.2 of Medtronic. We obtained a 3D image of the tracheobronchial tree which was used to create a pathway to reach the target (pulmonary nodule). The second phase was carried out directly at the operating room under general anesthesia. An electromagnetic field was generated by placing a board under the thorax of the patient combined with three electrodes. Then we performed a bronchoscopy with a locatable guide provided with an electrode to guide us through that field. Once reached the target, we administered 12MBq (0.2 ml) of 99mTC-MAA or 0.1 ml of the chosen dye (indocyanine green or methylene blue). The intrapulmonary deposit was confirmed with a portable gammacamera in the case of 99mTC-MAA and the activity measured in vivo. Finally, a video-assisted thoracoscopic surgery (VATS) was carried out. We used a gamma detector probe to localize the pulmonary region of maximum activity (hotspot) of 99mTC-MAA and a wedge resection was performed. In cases of dye marking, we localized directly the pleural surface coloured in green or in blue. We analyzed variables related to demography, navigation, surgery, postoperatory and histology. We considered a successful procedure when the central allocation of the lesion was situated within 1.5 cm of the hotspot or of the dye marking in the specimen.

Results: From 1st February 2022 to 31st March 2023 we localized 19 pulmonary nodules (mean size 9.4 mm, SD 4.2) in 15 patients combining ENB with 99mTC-MAA and/or dye marking. Mean time of ENB procedure was 16 minutes (SD 8.7). Mean time required to localize the hotspot intraoperatively was 1 minute (1-3) in cases of 99mTC-MAA. Successful rate was 84.2%. Four of the 19 nodules resected (21.1%) corresponded to sarcoma metastases (leiomyosarcoma, osteosarcoma and rhabdomyosarcoma; mean size 6.8 mm, SD 1.92), being all margins of resection microscopically free from tumour. (See Table 1).

Conclusion: Combining ENB with 99mTC-MAA or dye marking allowed us to localize small and peripheral pulmonary lesions, otherwise difficult to palpate by VATS. In our experience, it is a feasible, quick and reproducible technique, with a low rate of easily solved complications. Combination of BNE with 99mTC-MAA is a new option, not previously described, for localizing pulmonary nodules. Given the high incidence of pulmonary metastases from sarcomatous tumours during the evolution of the disease (in many cases small nodules difficult to palpate through minimally invasive approaches), we should have in mind BNE as a useful tool in cases of selected metastasectomy.