TRANSPARENCHYMAL MICROWAVE ABLATION ASSESSMENT IN A SURVIVAL PORCINE LUNG MODEL

Abstract

TOPIC: Procedures TYPE: Original Investigations PURPOSE: Percutaneous microwave ablation (MWA) is an established approach for CT-guided treatment of pulmonary tumors. A percutaneous approach for pulmonary MWA limits potential targets to peripheral lesions, and pneumothorax, hemorrhage, and fistula are some of the common complications. We have developed a system for bronchoscopic transparenchymal MWA of pulmonary tumors. Integration of the MWA system with virtual bronchoscopy and transparenchymal nodule access offers potential to enable minimally invasive diagnosis, staging, and treatment of peripheral lung nodules in a single session. In a survival porcine model, we assessed the feasibility of safely delivering MWA by introducing the applicator into lung targets via transparenchymal tunnel through the airway wall. METHODS: A total of 8 MWAs (90 W, 5 min) were performed in 4 pigs with a custom water-cooled, microwave catheter operating at 2.45 GHz. The catheter was introduced into multiple regions of the normal lung parenchyma via tunnels that extended 2.5–4 cm from the airway wall, guided by virtual bronchoscopy (Archimedes, Broncus Medical). Animals were euthanized at 2 (n=2) and 13 days (n=2) post-ablation. CT images were acquired immediately post-ablation and on the day of euthanasia. At necropsy, ablated and surrounding lung tissue was excised. Fresh tissue was used to assess the macroscopic extent of the ablation zones following viability staining. Formalin fixed tissue was processed into paraffin for thin sectioning and stained with hematoxylin and eosin for histopathologic examination. RESULTS: No pneumothorax, major bleeding or fistula were observed during and after ablation procedures. All pigs maintained normal appetite and behavior throughout the survival period. On day 2, ablation zone diameters on CT imaging were in the range 18–47 mm, as compared to 10–18 mm on macroscopic analysis. This discrepancy was likely due to edema, inflammation and/or hemorrhage obscuring the ablation boundary on CT assessment. At day 13, ablation zone diameters on CT imaging and macroscopic analysis were in the ranges 16–21 mm and 14–20 mm, respectively. On day 13, the ablation zone was separated from adjacent, aerated, pulmonary parenchyma by a 1-2 mm wide band of granulation tissue (fibrous connective tissue, fibrocytes, and vessels with macrophages and lymphoplasmacytic infiltrates). One of the animals in the 13-day group developed a severe suppurative bronchopneumonia attributed to secondary bacterial infection (the protocol did not include antibiotics). No evidence of emphysema was observed along the transparenchymal tunnels. CONCLUSIONS: We have demonstrated the feasibility of safely delivering virtual bronchoscopy guided transparenchymal MWA in a survival porcine model. CLINICAL IMPLICATIONS: Further evaluation of virtual-bronchoscopy guided transbronchial MWA in human patients in an ablate-and-resect study to assess safety and feasibility is warranted and planned for 2022. DISCLOSURES: No relevant relationships by Warren Beard, source=Web Response No relevant relationships by David Biller, source=Web Response No relevant relationships by Faraz Chamani, source=Web Response No relevant relationships by Pegah Faridi, source=Web Response Employee relationship with phenoMapper Please note: 09/01/2020-now Added 04/30/2021 by Steven Goh, source=Web Response, value=Salary No relevant relationships by Nicholas Hemphill, source=Web Response No relevant relationships by Margaret Highland, source=Web Response No relevant relationships by David Hodgson, source=Web Response No relevant relationships by Stephen Lam, source=Web Response PI ofan investigator-initiated study relationship with Medtronic Please note: >$100000 by Fabien Maldonado, source=Web Response, value=Grant/Research Supportco-I on investigator-initiated studies relationship with Janssen Please note: $20001 - $100000 by Fabien Maldonado, source=Web Response, value=Grant/Research Support Removed 04/19/2021 by Fabien Maldonado, source=Web Response PI on investigator-initiated relationship with Erbe Please note: $5001 - $20000 by Fabien Maldonado, source=Web Response, value=Grant/Research Support Consulting relationship with Medtronic Please note: $5001 - $20000 by Fabien Maldonado, source=Web Response, value=Honorariaco-I industry-sponsored trial relationship with Lung Therapeutics Please note: $5001 - $20000 by Fabien Maldonado, source=Web Response, value=Grant/Research Supportspeaker relationship with Longitudinal lung nodule fellows program - Please note: $1001 - $5000 by Fabien Maldonado, source=Web Response, value=Honoraria Removed 04/19/2021 by Fabien Maldonado, source=Web Response Board of director member relationship with AABIP Please note: $1-$1000 by Fabien Maldonado, source=Web Response, value=Travel No relevant relationships by Renelle Myers, source=Web Response No relevant relationships by Punit Prakash, source=Web Response No relevant relationships by Jan Sebek, source=Web Response No relevant relationships by Abbe Smith, source=Web Response No relevant relationships by Zixuan Wang, source=Web Response Owner/Founder relationship with phenoMapper, LLC Please note: 01/2021-12/2021 Added 04/30/2021 by Henky Wibowo, source=Web Response, value=Grant/Research Support No relevant relationships by Kun-Chang Yu, source=Web Response