Micron- to nanometer-sized ultrasound agents, like encapsulated microbubbles and echogenic liposomes, are being developed for diagnostic imaging and ultrasound mediated drug/gene delivery. This review provides an overview of the current state of the art of the mathematical models of the acoustic behavior of ultrasound contrast microbubbles. We also present a review of the in vitro experimental characterization of the acoustic properties of microbubble based contrast agents undertaken in our laboratory. The hierarchical two-pronged approach of modeling contrast agents we developed is demonstrated for a lipid coated (Sonazoid$$^\mathrm{TM})$$TM) and a polymer shelled (poly D-L-lactic acid) contrast microbubbles. The acoustic and drug release properties of the newly developed echogenic liposomes are discussed for their use as simultaneous imaging and drug/gene delivery agents. Although echogenicity is conclusively demonstrated in experiments, its physical mechanisms remain uncertain. Addressing questions raised here will accelerate further development and eventual clinical approval of these novel technologies.

中文翻译：

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用于对比超声成像和靶向药物输送的封装微泡和回声脂质体


微米到纳米尺寸的超声制剂，如封装的微泡和回声脂质体，正在开发用于诊断成像和超声介导的药物/基因递送。这篇综述概述了超声造影微泡声学行为数学模型的当前技术水平。我们还对我们实验室进行的基于微泡的造影剂的声学特性的体外实验表征进行了回顾。我们开发的分层双管齐下的建模造影剂方法被证明用于脂质涂层（Sonazoid$$^\mathrm{TM}）$$TM）和聚合物壳（聚DL-乳酸）造影微泡。讨论了新开发的回声脂质体作为同步成像和药物/基因递送剂的声学和药物释放特性。尽管回声性在实验中得到了最终证明，但其物理机制仍不确定。解决这里提出的问题将加速这些新技术的进一步开发和最终的临床批准。