Enhancement of Boiling Histotripsy by Steering the Focus Axially During the Pulse Delivery.
Enhancement of Boiling Histotripsy by Steering the Focus Axially During the Pulse Delivery.
复制标题
通过在脉冲传输过程中轴向控制焦点来增强沸腾组织解剖学。
DOI：
10.1109/tuffc.2023.3286759
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发表时间：
2023
期刊：
影响因子：
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通讯作者：
Khokhlova,VeraA
中科院分区：
文献类型：
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作者：
Thomas,GillesPL;Khokhlova,TatianaD;Sapozhnikov,OlegA;Khokhlova,VeraA
沸腾组织摧毁术（BH）是一种脉冲高强度聚焦超声（HIFU）方法，依赖于在焦点处产生高振幅冲击、局部增强冲击波加热以及由冲击驱动的气泡活动来诱导组织液化。BH使用具有超过60 MPa振幅的冲击波阵面的1-20 ms长的脉冲序列，在每个脉冲内在HIFU换能器的焦点处引发沸腾，并且脉冲的剩余冲击然后与沸腾蒸汽腔相互作用。这种相互作用的一个效果是由于来自最初产生的mm大小的空腔的冲击的反射而产生预聚焦气泡云：当从压力释放空腔壁反射时，冲击被反转，从而产生足够的负压以达到空腔前面的固有空化阈值。由于第一层云的冲击波散射，形成了次级云。这种焦前气泡云的形成被认为是BH中组织液化的机制之一。在这里，提出了一种方法来扩大轴向尺寸的气泡云转向后，直到每个BH脉冲结束沸腾的换能器的HIFU焦点，从而加速治疗。使用包括连接到Verasonics V1系统的1.5MHz 256元件相控阵列的BH系统。在透明凝胶中进行BH声处理的高速摄影，以观察由冲击反射和散射引起的气泡云的延伸。体积BH病变，然后在离体组织中使用所提出的方法产生。结果显示，与标准BH相比，BH脉冲输送期间轴向焦点转向的组织消融率增加了近三倍。
Boiling histotripsy (BH) is a pulsed high-intensity focused ultrasound (HIFU) method relying on the generation of high-amplitude shocks at the focus, localized enhanced shock-wave heating, and bubble activity driven by shocks to induce tissue liquefaction. BH uses sequences of 1–20 ms long pulses with shock fronts of over 60 MPa amplitude, initiates boiling at the focus of the HIFU transducer within each pulse, and the remainder shocks of the pulse then interact with the boiling vapor cavities. One effect of this interaction is the creation of a prefocal bubble cloud due to reflection of shocks from the initially generated mm-sized cavities: the shocks are inverted when reflected from a pressure-release cavity wall resulting in sufficient negative pressure to reach intrinsic cavitation threshold in front of the cavity. Secondary clouds then form due to shock-wave scattering from the first one. Formation of such prefocal bubble clouds has been known as one of the mechanisms of tissue liquefaction in BH. Here, a methodology is proposed to enlarge the axial dimension of this bubble cloud by steering the HIFU focus toward the transducer after the initiation of boiling until the end of each BH pulse and thus to accelerate treatment. A BH system comprising a 1.5 MHz 256-element phased array connected to a Verasonics V1 system was used. High-speed photography of BH sonications in transparent gels was performed to observe the extension of the bubble cloud resulting from shock reflections and scattering. Volumetric BH lesions were then generated in ex vivo tissue using the proposed approach. Results showed up to almost threefold increase of the tissue ablation rate with axial focus steering during the BH pulse delivery compared to standard BH.