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Objectives: This study aimed to explore the interactions between microbubbles and microwave ablation (MWA). Methods: The study employed custom‐made phantoms (in vitro) and white New Zealand rabbits (in vivo). MWA was performed with or without microbubbles in the phantoms (2 × 105 particles mL−1) and rabbit livers (intravenous injection of 0.05 mL/kg SonoVue). During the MWA, K‐type thermocouple probes were used to monitor the MWA‐induced temperature increase. Contrast‐enhanced ultrasound imaging (CEUS) was used to monitor and analyze the microbubbles signal intensity. After MWA, the ablation‐zone volumes were evaluated and compared between the groups with and without microbubbles. Results: In both the phantom models and rabbits, microbubbles showed no significant influence on MWA, including the ablation range and MWA‐induced temperature increase. In phantoms and rabbit livers filled with microbubbles, MWA caused the formation of a gradually expanding microbubble‐defect region over the ablation time. An increase in the temperature caused microbubble destruction. Conclusions: Microbubbles had no significant influence on MWA. However, MWA induced the destruction of microbubbles in a temperature‐dependent manner. Thus, the poor thermotolerance of microbubbles is a non‐negligible barrier when using CEUS to monitor the ablation range during MWA in real‐time. [ABSTRACT FROM AUTHOR]

To determine the effects of tract embolization with gelatin sponge particles on the prevention of pneumothorax after percutaneous microwave ablation (MWA) in rabbit lungs. Twenty-four New Zealand white rabbits were randomly divided into Group A (MWA followed by tract embolization with gelatin sponge particles, n = 12) and Group B (MWA without tract embolization, n = 12). For each group, CT images were reviewed for the occurrence of pneumothorax within 30 min after MWA. The rate of pneumothorax was compared by Chi-square Test. Lung tissue around the needle tract was harvested after the rabbits were euthanized, and histopathological examinations were performed and studied with hematoxylin and eosin stains. Twenty-four animals underwent 47 sessions of MWA (24 sessions in Group A and 23 sessions in Group B). Group A had a statistically lower rate of pneumothorax than Group B (25.0 vs. 56.5%; p = 0.028). The pathological examinations of both groups demonstrated thermal injury of the needle tract characterized by a rim of the coagulated lung parenchyma, which might be responsible for pneumothorax after MWA. Gelatin sponge particles could be arranged in irregular flakes densely to effectively seal the needle tract, thus reducing the occurrence of pneumothorax. The gelatin sponge particles could be almost completely absorbed about 14 days later. Results of the present study showed needle tract embolization with gelatin sponge particles after CT-guided pulmonary MWA can significantly reduce the incidence of pneumothorax. Gelatin sponge particles can effectively seal the needle tract after ablation and can be completely absorbed in the body with good safety. [ABSTRACT FROM AUTHOR]