Ex Vivo Performance of a Flexible Microwave Ablation Antenna.

OBJECTIVE In this study, we investigate the performance of a flexible microwave ablation antenna for generating localized ablation zones. METHODS We designed a helical dipole antenna to operate at 1.9 GHz in egg white and liver. Semi-rigid prototypes of the antenna were fabricated and used to perform ablation experiments in egg white and perfused liver. Pulsed and continuous-wave power deliveries at different power levels were used. Flexible prototypes of the antenna were fabricated and used to perform ex vivo ablation experiments in perfused liver. RESULTS Pulsing was effective in reducing the shaft heating of semi-rigid cables. The antenna was capable of producing substantial ablation zones in perfused liver. Typical diameters (perpendicular to the antenna axis) of generated ablation zones with semi-rigid antennas in egg white and perfused liver were 30 mm and 20 mm, respectively. The flexible antenna had a good impedance match while bent. Average diameter of generated ablation zones by the flexible antenna with 10-W continuous wave experiments in perfused liver was 26 mm. No significant difference was observed between the performances of semi-rigid and flexible prototypes. CONCLUSION The flexible helical dipole antenna is capable of maintaining its good impedance match while bent and can generate substantial ablation zones in presence of perfusion. SIGNIFICANCE The proposed flexible antenna is promising for minimally invasive treatment of tumors that are otherwise inaccessible by rigid antennas. One example is lung where a catheter-based deployment of the flexible antenna into the tumor via airways may substantially reduce risks associated with using rigid antennas.