Flexible microwave ablation applicator for the treatment of pulmonary malignancies

Microwave ablation (MWA) is an emerging minimally invasive treatment option for malignant lung tumors. Compared to other energy modalities, such as radiofrequency ablation, MWA offers the advantages of deeper penetration within high impedance tissues such as aerated lung, shorter treatment times, and less susceptibility to the cooling heat-sink effects of air and blood flow. Previous studies have demonstrated clinical use of MWA for treating lung tumors; however, these procedures have relied upon the percutaneous application of rigid microwave antennas. The objective of our work was to develop and characterize a novel flexible microwave applicator which could be integrated with a bronchoscopic imaging and software guidance platform to expand the use of MWA as a treatment option for small (< 2cm) pulmonary tumors. This applicator would allow physicians an even less invasive, immediate treatment option for lung tumors identified within the scope of current medical procedures. It may also improve applicator placement accuracy and increase efficacy while minimizing the risk of procedural complications. A 2D-axisymmetric coupled FEM electromagnetic-heat transfer model was implemented to characterize expected antenna radiation patterns, ablation size and shape, and optimize antenna design for lung tissue. A prototype device was fabricated and evaluated in ex vivo tissues to verify simulation results and serve as proof-of-concept. Additional experiments were conducted in an in vivo animal model to further characterize the proposed system.