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首页> 外文期刊>IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control >Optical and acoustical observations of the effects of ultrasound oncontrast agents
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Optical and acoustical observations of the effects of ultrasound oncontrast agents

机译：超声对造影剂影响的光学和声学观察

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Optimal use of encapsulated microbubbles for ultrasound contrastnagents and drug delivery requires an understanding of the complex set ofnphenomena that affect the contrast agent echo and persistence. With thenuse of a video microscopy system coupled to either an ultrasound flownphantom or a chamber for insonifying stationary bubbles, we show thatnultrasound has significant effects on encapsulated microbubbles. Innvitro studies show that a train of ultrasound pulses can alter thenstructure of an albumin-shelled bubble, initiate various mechanisms ofnbubble destruction or produce aggregation that changes the echonspectrum. In this analysis, changes observed optically are compared withnthose observed acoustically for both albumin and lipid-shelled agents.nWe show that, when insonified with a narrowband pulse at an acousticnpressure of several hundred kPa, a phospholipid-shelled bubble cannundergo net radius fluctuations of at least 15%; and an albumin-shellednbubble initially demonstrates constrained expansion and contraction. Ifnthe albumin shell contains air, the shell may not initially experiencensurface tension; therefore, the echo changes more significantly withnrepeated pulsing. A set of observations of contrast agent destruction isnpresented, which includes the slow diffusion of gas through the shellnand formation of a shell defect followed by rapid diffusion of gas intonthe surrounding liquid. These observations demonstrate that thenlow-solubility gas used in these agents can persist for several hundrednmilliseconds in solution. With the transmission of a high-pulsenrepetition rate and a low pressure, the echoes from, contrast agents cannbe affected by secondary radiation force. Secondary radiation force isnan attractive force for these experimental conditions, creatingnaggregates with distinct echo characteristics and extended persistence.nThe scattered echo from an aggregate is several times stronger and morennarrowband than echoes from individual bubbles
机译：为超声造影剂和药物输送最佳地使用封装的微泡，需要了解影响造影剂回声和持久性的复杂现象。然后，使用视频显微镜系统，将其耦合到超声流管或用于声波固定气泡的腔室，我们显示了超声对封装的微气泡具有重要影响。 Innvitro研究表明，一系列超声波脉冲可以改变带壳蛋白的气泡的结构，引发各种气泡破坏机制或产生聚集物，从而改变超声光谱。在此分析中，将用光学方法观察到的变化与通过声学方法观察到的对于白蛋白和脂质带壳试剂的变化进行了比较.n我们表明，当在几百kPa的声压下用窄带脉冲进行声波照射时，磷脂壳气泡会经历至少15％；白蛋白带壳的气泡最初显示出受约束的膨胀和收缩。如果白蛋白外壳中含有空气，则外壳最初可能不会经受表面张力；因此，在没有重复脉冲的情况下，回声变化更为明显。提出了一系列造影剂破坏的观察结果，包括气体通过壳的缓慢扩散和壳缺陷的形成，然后气体迅速扩散到周围的液体中。这些观察结果表明，这些试剂中使用的低溶解度气体可以在溶液中持续数百毫微秒。通过高脉冲重复率和低压的传输，造影剂的回波不会受到二次辐射力的影响。在这些实验条件下，次级辐射力是南引力，产生具有明显回波特性和持久性的团聚体。n团聚体的散射回波比单个气泡的回波强和窄带几倍。

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