Dual-beam histotripsy: a low-frequency pump enabling a high-frequency probe for precise lesion formation.
Dual-beam histotripsy: a low-frequency pump enabling a high-frequency probe for precise lesion formation.
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DOI：
10.1109/tuffc.2014.6722617
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发表时间：
2014-02
期刊：
影响因子：
--
通讯作者：
Cain CA
中科院分区：
文献类型：
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作者：
Lin KW;Duryea AP;Kim Y;Hall TL;Xu Z;Cain CA
组织破碎术通过短的高压超声脉冲产生的密集的高能气泡云产生组织分离。当使用短于2个周期的脉冲时，这些高能气泡云的产生仅取决于峰值负压（P-）超过介质的固有阈值（在具有高含水量的软组织中为26 - 30 MPa）的位置。本文研究了一种用于精确损伤生成的策略方法，其中应用低频泵浦脉冲以使亚阈值高频探测脉冲超过固有阈值。这种控制超阈值体积的泵浦-探测方法可以称为“双光束组织摧毁术”。使用20个元件双频（500 kHz和3 MHz元件共焦对齐）阵列换能器在RBC模型和猪肝组织标本中产生双束组织破坏脉冲。结果表明，当亚本征阈值泵（500 kHz）和探针（3 MHz）脉冲一起施加时，只有当它们的峰值负压相结合超过本征阈值时，才会产生密集的气泡云（和由此产生的病变）。最小的可再现损伤随泵脉冲和探针脉冲之间的相对幅度而变化，并且，随着探针脉冲的比例更高，可以产生更小的损伤。当探测脉冲相对于泵浦脉冲的传播方向改变时，所产生的损伤的形状基于超过固有阈值的区域而改变。由于低频泵浦脉冲更不受衰减和畸变的影响，而高频探测脉冲可以提供精确的损伤形成，因此这种双光束组织摧毁方法在需要通过高度衰减和畸变介质精确损伤形成的情况下（例如经颅治疗）非常有用。如果小的低衰减声窗可用于高频探头换能器，则尤其如此。
Histotripsy produces tissue fractionation through dense energetic bubble clouds generated by short, high-pressure, ultrasound pulses. When using pulses shorter than 2 cycles, the generation of these energetic bubble clouds only depends on where the peak negative pressure (P–) exceeds an intrinsic threshold of a medium (26 – 30 MPa in soft tissue with high water content). This paper investigates a strategic method for precise lesion generation in which a low-frequency pump pulse is applied to enable a sub-threshold high-frequency probe pulse to exceed the intrinsic threshold. This pump-probe method of controlling a supra-threshold volume can be called “dual-beam histotripsy.” A 20-element dual-frequency (500 kHz and 3 MHz elements confocally aligned) array transducer was used to generate dual-beam histotripsy pulses in RBC phantoms and porcine hepatic tissue specimens. The results showed that, when sub-intrinsic-threshold pump (500 kHz) and probe (3 MHz) pulses were applied together, dense bubble clouds (and resulting lesions) were only generated when their peak negative pressures combined constructively to exceed the intrinsic threshold. The smallest reproducible lesion varied with the relative amplitude between the pump and probe pulses, and, with a higher proportion of the probe pulse, smaller lesions could be generated. When the propagation direction of the probe pulse relative to the pump pulse was altered, the shape of the produced lesion changed based on the region that exceeded intrinsic threshold. Since the low-frequency pump pulse is more immune to attenuation and aberrations, and the high-frequency probe pulse can provide precision in lesion formation, this dual-beam histotripsy approach would be very useful in situations where precise lesion formation is required through a highly attenuative and aberrative medium, such as transcranial therapy. This is particularly true if a small low-attenuation acoustic window is available for the high-frequency probe transducer.