E-ISSN 1305-3612
Original Article
Subsequent cooling-circulation after radiofrequency and microwave ablation avoids secondary indirect damage induced by residual thermal energy
Xinyi Shi 1 ,  
Hong Pan 1 ,  
Han Ge 1 ,  
Li Li 1 ,  
Yi Xu 2 ,  
Cong Wang 2 ,  
Hui Xie 1 ,  
1 Department of Breast Surgery, the First Affiliated Hospital of Nanjing Medical University, Nanjing, China  
2 Department of Pathology, the First Affiliated Hospital of Nanjing Medical University, Nanjing, China  
Diagn Interv Radiol ; : -

Abstract

PURPOSE: To determine the exact role of residual thermal (the thermal energy released from the zone after ablation) in microwave ablation (MWA) and radiofrequency ablation (RFA) at the final ablation zoneand transition zone, and whether residual thermal could be removed by subsequent cooling-circulation.


METHODS
: In an ex vivo study, MWA and RFA were performed on fresh porcine liver, and the central temperature and border temperature were compared. In an in vivo study, MWA and RFA were performed to the livers of New Zealand white rabbits. Tissue samples were stained with α-NADH-diaphorase. The coagulation zones (NADH-negative) and transition zones (lightly NADH-stained) of different groups were compared at different time points.


RESULTS
: In the ex vivo model, the residual thermal energy after MWA and RFA could be dispersed by subsequent cooling-circulation due to the temperature decreasing rapidly. In the in vivo study, the coagulation volume in the ablation group was larger than that in the cooling-circulation group (P< 0.05) 2 days after ablation. In the ablation group, the damaged zone (the transition zone plus the coagulation zone) on α-NADH-diaphorase-stained images increased rapidly within 2 hours after ablation and slowly reached the maximum on day 2. However, there were no significant differences among the damaged zones at the three time points in the cooling-circulation group.


CONCLUSION
: The residual thermal energy in MWA and RFA induced secondary damage beyond the direct coagulation zone, and it could be removed by subsequent cooling-circulation, contributing to smaller ablation zoneand transition zone.

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