Characteristics of laparoscopic microwave ablation with renal tissue: Experimental in vivo study using a porcine model

Abstract

Purpose: A model of in vivo porcine kidneys is used to clarify the characteristics of laparoscopic microwave ablation (MWA) of renal tissue. Materials and methods: Six pigs were utilised for the experiment using 18G water circulating-cooling microwave needles. The operating frequency was 2450 MHz, and the independent variables were power (50–60 W) and time (300–600 s). The kidneys were dissociated laparoscopically and ablated with a single or double needle at different power/time combinations and depths of puncture. Changes in the kidneys were carefully observed. Specimens of the ablated lesions were stained with haematoxylin-eosin (H&E) to evaluate the pathological features. Results: Thirty-four thermoablations were applied. The effective ablation shape was similar to a chestnut. The ablated lesions could be divided into three zones: carbonization zone, coagulation zone, and inflammatory reaction zone. The ablation zone enlarged with increasing power and time. When combined with two needles, the maximum diameter of the ablated lesions significantly increased. Pathological results indicated that renal tissues of the carbonisation zone were thoroughly necrotic. Coagulative necrosis was observed in the coagulation zone. No ‘skipped’ areas were noted in any ablation zone. The structure of the inflammatory reaction zone was integrated, and interstitial small blood vessels were highly expanded and congested with infiltrated inflammatory cells. Conclusions: MWA achieved excellent effects in this porcine model. It can be safely and effectively used in renal tissue. For patients with poor physical condition or small renal masses (<4 cm), we can refer to these data and select the appropriate combinations to obtain satisfactory therapeutic efficacy.

• Ablation techniques
• laparoscope
• kidney neoplasms
• microwave

Acknowledgements

Division of author responsibilities: data collection, management, analysis and manuscript writing, Baoan Hong; project development and manuscript editing, Ning Zhang; help with the pathological image analysis, Yuan Zhao; experiment instruction, Xiaodong Zhang and Yong Yang; help with data collection and management, Xin Du and Guowei Chen. We would also like to express our thanks to Kefei Qi, Jun Zhang, and Yi Wang from Nanjing KangYou company for their expertise in MWA instruments.

Declaration of interest

This study was supported by the 2014 Beijing Natural Science Foundation (grant no.7142059). The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.