Comparison of Microwave and Radiofrequency Ablation of Hepatic Tissue in a Porcine in vivo Model.
Comparison of Microwave and Radiofrequency Ablation of Hepatic Tissue in a Porcine in vivo Model. Andrew Wright MD, Chris Johnson, Fred Lee Jr. MD, and David Mahvi MD. Departments of Radiology and Surgery University of Wisconsin Hospital. Microwave Ablation.
Comparison of Microwave and Radiofrequency Ablation of Hepatic Tissue in a Porcine in vivo Model.
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Comparison of Microwave and Radiofrequency Ablation of Hepatic Tissue in a Porcine in vivo Model. Andrew Wright MD, Chris Johnson, Fred Lee Jr. MD, and David Mahvi MD Departments of Radiology and Surgery University of Wisconsin Hospital
Microwave Ablation • Theoretical advantages over radiofrequency ablation • No ground pad • Not limited by tissue charring and impedence changes • Larger zone of active heating • Use of Multiple Probes
Hypothesis • Because microwave and radiofrequency ablation are both heat based, there will be no difference in ablation size or lesion pathology between the two technologies
Methods • Microwave Ablation • Vivant Medical prototype system • 10 minute ablation, 40 Watts • Radiofrequency Ablation • RITA Medical Systems Starburst • 10 minute ablation, 3cm deployment 100oC target temperature
Microwave Ablation System • Vivant Medical • 13g, 15cm dipole antenna • 915MHz generator • Fiberoptic temperature monitor
Radiofrequency Ablation System • RITA Medical • 14g, 15cm expandable array • 460 kHz generator • Integrated thermocouple
Treatment Protocol • Nineteen crossbred female swine • 0, 2, and 28 day survival groups • Mix of MW and RF lesions in each animal • Pathology, serial CT scanning • 28 Day survival group • 4 MW or 4 RF lesions in each animal • Pathology, serial lab draws
Lesion Volume * * * p=.02
Lesion Length * ▪ ▪ ◦ * ◦ * p<.001 ▪ p=.02 ◦ p<.001
Laboratory Data • No significant difference in AST, ALT, LDH, Alkaline Phosphatase, WBC, or HCT * * p<0.001
48o Pathology RFA MW Immediate 4 weeks
CT Imaging 48 Hours 4 Weeks
Summary • MW lesions longer than RF • Pathological and radiologic characteristics similar between RF and MW ablation • Both MW and RF cause thrombocytopenia at 48 hours • MW ablation technically easier than multiple-prong RF ablation
Conclusions • MW creates similar zones of coagulation necrosis as RF • MW ablation has several theoretical advantages over RF • Larger zone of active heating • Ability to use multiple probes