Effect of microbubble-enhanced ultrasound on percutaneous ethanol ablation of rat walker-256 tumour

Objectives: Percutaneous ethanol ablation (PEA) is an effective method for treating small liver cancer. Microbubble-enhanced ultrasound (MEUS) can potentially promote PEA by disrupting the tumour’s circulation. In this study, treatment combining MEUS and PEA was performed to find any synergistic effects in tumour ablation. Methods: Ten rats bearing subcutaneous Walker-256 tumours were treated by MEUS combined with PEA. The other 18 tumour-bearing rats that were treated by MEUS or PEA served as the controls. MEUS was conducted by therapeutic ultrasound (TUS) and microbubble injection. TUS was operated at a frequency of 831 KHz with a pressure amplitude of 4.3 MPa. Tumour blood perfusion was assessed by contrast-enhanced ultrasound (CEUS), and the tumour necrosis rate was determined by histological examination. Results: CEUS showed that the tumour blood perfusion almost vanished in all of the MEUS-treated tumours. The contrast peak intensity dropped 84.8 % in the MEUS + PEA-treated tumours when compared to 46.3 % (p < 0.05) in the PEA-treated tumours 24 h after treatment. The tumour necrosis rate of the combination therapy was 97.50 %, which is much higher than that of the MEUS- (66.2 %) and PEA-treated (81.0 %) tumours. Conclusion: PEA combined with MEUS can induce a much more complete tumour necrosis. Key Points: • This experiment demonstrated a novel method for enhancing percutaneous ethanol ablation. • Microbubble-enhanced therapeutic ultrasound is capable of disrupting tumour circulation. • Combined therapy of MEUS and PEA can induce more complete necrosis of tumours.