Microbubbles assist goat liver ablation by high intensity focused ultrasound
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High intensity focused ultrasound (HIFU) has been introduced to treat cancers. However, this therapy is a time-consuming procedure; destructing a deeper volume is also difficult as ultrasonic energy attenuates exponentially with increasing depth in tissues. The aim of the present study was to investigate the effects of introducing microbubbles on liver HIFU ablation. Seventeen goats were divided into groups A (n=8) and B (n=9). The livers in both groups were ablated using HIFU (1.0 MHz, 22,593 W/cm2) performed in the manner of a clinical regime using a clinical device. A microbubble agent was bolus-injected intravenously before HIFU exposure in group B. All animals in group A and seven goats in group B were euthanased to evaluate the ablation efficiency 24 h after HIFU. The necrosis rate (mm3/s), which was the volume of necrosis tissue per second of HIFU exposure, was used to judge the ablation efficiency. Pathological examinations were performed to determine whether there were residual intact tissues within the exposed volume. The other two goats in group B were used to determine the delayed pathological changes 7 days after ultrasonic ablation. The necrosis rate (mm3/s) was increased in group B (14.4647±4.1960 versus 33.5302±12.4484, P=0.0059). Pathological examinations confirmed that there were no residual unaffected tissue focuses within the exposed volume. Two remarkable changes occurred in the other two goats in group B 7 days after HIFU: there were ghost-cell islands at the periphery of the ablated tissues, and surrounding adjacent tissues outside the reactive zone necrotized. These findings showed that microbubbles could be used to assist liver HIFU ablation.
KeywordsHigh intensity focused ultrasound Liver Microbubble Ablation efficiency Delayed necrosis
- 9.Stride E, Saffari A (2003) Microbubble ultrasound agents: a review. Proc Inst Mech Eng [H] 217:429–447Google Scholar
- 17.Wang W, Zhou J, Liu W, Bai L, Ye H, Gai L, Tan Y, Yang T (2002) Treatment of unresectable nodular hepatocellular carcinoma with high-intensity focused ultrasound combined transarterial oily chemoembolization: preliminary clinical outcomes. In: Andrew MA, Crum LA, Vaezy A (eds) Proceedings of 2nd International Symposium on Therapeutic Ultrasound, University of Washington, pp 44–50Google Scholar
- 20.Fry FJ (1991) Intense focused ultrasound in medicine. Eur Urol 23 (Suppl 1):2–7Google Scholar
- 24.Umemura S, Kawabata K, Sanghvi N, Sasaki K (2002) Enhancement of ultrasonic adsorption by microbubble agent for HIFU. In: Andrew MA, Crum LA, Vaezy A (eds). Proceedings of 2nd International Symposium on Therapeutic Ultrasound, University of Washington, pp 527–538Google Scholar