Encapsulated microbubbles and echogenic liposomes for contrast ultrasound imaging and targeted drug delivery.

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™) 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.

微米至纳米尺寸的超声造影剂，如包裹的微泡和回声脂质体，正被开发用于诊断成像以及超声介导的药物/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。我们还综述了在我们实验室进行的基于微泡的造影剂声学特性的体外实验表征。我们所开发的对造影剂进行建模的分层双管齐下的方法，针对一种脂质包裹的（索纳佐伊德™）和一种聚合物外壳的（聚D - L -乳酸）造影微泡进行了展示。讨论了新开发的回声脂质体作为同时用于成像和药物/基因递送的试剂的声学和药物释放特性。尽管在实验中确凿地证明了回声性，但其物理机制仍不确定。解决此处提出的问题将加速这些新技术的进一步发展以及最终的临床批准。