Single 15-Min Protocol Yields the Same Cryoablation Size and Margin as the Conventional 10–8–10-Min Protocol: Results of Kidney and Liver Swine Experiment
The objective was to determine the ablation size of a single 15-min freeze and compare it with the conventional 10-min freeze–8-min thaw–10-min freeze protocol. Secondary objectives were to determine the ablation margin and to ascertain whether islands of viable tissue remain within the ablation zone.
Materials and Methods
Five adult swine under general anesthesia were used. After surgical abdominal exposure, two ablations were performed in liver and two in kidney. One ablation utilized the 15-min and the second the 10–8–10-min protocol. At maximum ice-ball, tissue ink was infused via an angiographic catheter in hepatic or renal artery to stain the non-frozen tissue. Animals were euthanized and organs examined macro- and microscopically.
Three histological regions were observed: (A) a viable/stained region representing the tissue outside the ice-ball, (B) a central necrotic area representing the ablated region within the ice-ball and (C) an unstained but viable margin representing the non-lethal margin within ice-ball. Ablation size did not vary with protocol but did for tissue type. Renal ablation was approximately 5 × 4 cm with both protocols, whereas liver ablation was approximately 6.7 × 4.4 cm. Ablation margin was measured at 1 mm irrespective of ablation protocol or tissue. No islands of viable tissue were identified within the ablation zone.
Fifteen-minute cryoablation yielded an ablation size and margin identical to that of the conventional 10–8–10-min protocol. Within the ablated region, cell death was uniform. The only difference was a larger cryoablation zone in hepatic tissue compared to renal tissue, likely attributable to differences in blood perfusion.
KeywordsCryoablation Margin Ablation size
The study was supported by Galil Medical.
Compliance with Ethical Standards
Conflict of interest
Senior author is a consultant for Galil Medical. On behalf of the other authors, the corresponding author states that there is no conflict of interest.
The study was approved by the Johns Hopkins University Animal Care & Use Committee.
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