Tung Yao-Sheng, Liu Hao-Li, Wu Chih-Ching, Ju Kuen-Cheng, Chen Wen-Shiang, Lin Win-Li
Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan.
Ultrasound Med Biol. 2006 Jul;32(7):1103-10. doi: 10.1016/j.ultrasmedbio.2006.04.005.
The small thermal lesions induced when using high-intensity focused ultrasound (HIFU) to ablate tumors results in long treatment duration. In this study, the effect of using ultrasound contrast agent (UCA, Definity) to enhance the ultrasound (US) thermal effects and, thus to enlarge the lesion size, was studied in transparent tissue phantoms insonified by 1.85-MHz US with acoustical powers of 28.9 and 40.4 W. The experimental results show that the lesion size depended strongly on the electrical power and the concentration of UCA. UCA also reduced the power required to form a lesion of a certain size by about 30%. However, UCA moved the greatest heating position from the transducer focus, by 2.16 cm for 0.015% UCA at 40.4 W, and with lesions forming at the surface for UCA concentrations higher than 0.1%. An optimal result was obtained when using 0.001% UCA and 28.9-W US, which produced a lesion 12 times larger and an acceptable shift (less than half of the lesion length). UCA can effectively increase the size of the HIFU lesions, but lesion shift should be carefully considered while performing HIFU ablations.
使用高强度聚焦超声（HIFU）消融肿瘤时产生的微小热损伤会导致治疗时间延长。在本研究中，研究了在由1.85MHz超声以28.9W和40.4W的声功率进行超声照射的透明组织仿体中，使用超声造影剂（UCA，Definity）增强超声热效应从而扩大损伤尺寸的效果。实验结果表明，损伤尺寸强烈依赖于电功率和UCA浓度。UCA还使形成一定尺寸损伤所需的功率降低了约30%。然而，UCA使最大加热位置从换能器焦点发生了移动，在40.4W功率下，0.015%的UCA使其移动了2.16cm，且当UCA浓度高于0.1%时，损伤在表面形成。使用0.001%的UCA和28.9W的超声可获得最佳结果，其产生的损伤大12倍且位移可接受（小于损伤长度的一半）。UCA可有效增加HIFU损伤的尺寸，但在进行HIFU消融时应仔细考虑损伤位移。
