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Multiprobe RF ablation: A Feasibility Study

Multiprobe RF ablation: A Feasibility Study. Fred T. Lee Jr., MD Dieter Haemmerich, MS Andrew S. Wright, MD David M. Mahvi, MD John G. Webster, PhD. University of Wisconsin Depts. Of Radiology, Bioengineering, Surgery. Why multiprobe RF?. Why multiprobe RF?. Why multiprobe RF?.

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Multiprobe RF ablation: A Feasibility Study

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  1. Multiprobe RF ablation: A Feasibility Study Fred T. Lee Jr., MD Dieter Haemmerich, MS Andrew S. Wright, MD David M. Mahvi, MD John G. Webster, PhD University of Wisconsin Depts. Of Radiology, Bioengineering, Surgery

  2. Why multiprobe RF?

  3. Why multiprobe RF?

  4. Why multiprobe RF?

  5. Why multiprobe RF? • Simultaneous ablations • Increase lesion number • Multiple probes in large tumor • Decrease ablation time • Improve temperature distribution in lesion (make ablation more effective) • Control lesion (bigger not always better)

  6. Current RF systems • Multiple prongs run at same voltage RITA Radionics RTC

  7. Faraday Effect

  8. Faraday Effect Electrodes at same voltage

  9. Faraday Effect Probes at different voltage=bipolar Current flows between probes

  10. Faraday Effect Electrically independent probes

  11. How independent probes created • Rapid switching between probes • Temperature in tissue changes much slower than switching • Temperature/impedance feedback algorithm

  12. How independent probes created

  13. Prototype dual probe unit

  14. Prototype dual probe unit

  15. Ex vivo results: Dual probes in pig liver at same temperature

  16. In vivo results • Domestic pigs (n=3, mean wt=35 kg) • 13 RF lesions • 3 single control lesions • 10 dual (5 pairs created simultaneously) RITA Model 150 generator (150 W), Starburst electrode deployed to 3.0 cm. 10 minute ablation, 100° C.

  17. In vivo results vs Single Simultaneous dual RF Note: same scale

  18. In vivo results • Time to temperature (100°C) single: 2.7 minutes (162 seconds) dual: 3.4 minutes (204 seconds)

  19. In vivo results:volume of necrosis • Single: 10.7 cc • Dual (each individual lesion): 17.3cc Therefore, 34.6 cc ablation obtained in approximately same time as 10.7 cc ablation

  20. In vivo results:max diameter • Single: 3.3 cm • Dual (each individual lesion): 3.8 cm

  21. Conclusions • Feasible to create multiple simultaneous burns with a single generator • No lesion size penalty • Slight increase in time to temperature

  22. What’s next? • Increase # of probes (?4) • Will require increased generator power • Many technical factors involved with rapid switching (mechanical electrical) • Cluster probes in close proximity to increase lesion size, temperature

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