Pulsed focused ultrasound-induced displacements in confined in vitro blood clots.
Pulsed focused ultrasound-induced displacements in confined in vitro blood clots.
复制标题
脉冲聚焦超声引起的体外有限血凝块位移。
DOI：
10.1109/tbme.2011.2180904
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
Goertz,DavidE
中科院分区：
文献类型：
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作者：
Wright,CameronC;Hynynen,Kullervo;Goertz,DavidE
在一系列体外和体内研究以及临床试验中，超声波已被证明可增强组织纤溶酶原激活剂的作用，以改善凝块溶解。一种可能的作用机制是声辐射力诱导的凝块移位。在这项研究中，我们调查的时间和空间动态凝块位移和应变发起的聚焦超声脉冲。在琼脂血管体模通道内约束的凝块中，通过1.51 MHz f数1换能器在声功率范围（1-85 W）内产生位移。使用20 MHz高频超声成像探头在5.45 ms治疗脉冲期间和之后跟踪位移。峰值血栓位移被发现是声功率的线性函数，直到60 W，然后在最高发射功率的128 μm附近趋于平稳。血凝块的峰值位移时间和恢复时间在很大程度上与声功率无关，测量值接近2 ms。观察到峰值轴向应变与发射功率之间的线性关系，在35 W时达到峰值11%。对于横向和轴向研究的所有屈光度，峰值应变发生在距离焦点区约0.75 mm处。这些结果表明，大量的位移可以引起的聚焦超声在封闭的血凝块，空间和时间的位移模式是复杂的，高度依赖于暴露条件，这对未来的工作有影响，调查他们的联系，凝块溶解和开发方法，利用这些效果。
Ultrasound has been shown to potentiate the effects of tissue plasminogen activator to improve clot lysis in a range of in vitro and in vivo studies as well as in clinical trials. One possible mechanism of action is acoustic radiation force-induced clot displacements. In this study, we investigate the temporal and spatial dynamics of clot displacements and strain initiated by focused ultrasound pulses. Displacements were produced by a 1.51 MHz f-number 1 transducer over a range of acoustic powers (1-85 W) in clots constrained within an agar vessel phantom channel. Displacements were tracked during and after a 5.45 ms therapy pulse using a 20 MHz high-frequency ultrasound imaging probe. Peak thrombus displacements were found to be linear as a function of acoustic power up to 60 W before leveling off near 128 μm for the highest transmit powers. The time to peak displacement and recovery time of blood clots was largely independent of acoustic powers with measured values near 2 ms. A linear relationship between peak axial strain and transmit power was observed, reaching a peak value of 11% at 35 W. The peak strain occurred ~0.75 mm from the focal zone for all powers investigated in both lateral and axial directions. These results indicate that substantial displacements can be induced by focused ultrasound in confined blood clots, and that the spatial and temporal displacement patterns are complex and highly dependent on exposure conditions, which has implications for future work investigating their link to clot lysis and for developing approaches to exploit these effects.