Acoustic Contrast Agents for Use with High-frequency Ultrasound

描述(由申请人提供)：这项研究的目标是利用高频超声(HFU，&GT；10 MHz)的声学造影剂，以成像微循环并通过声孔法启动基因导入。目前的造影剂并不是为这些高频而设计的。这项研究将评估两个重要的应用：1)兔眼和小鼠胚胎中慢流微血管的成像；2)在小鼠胚胎中启动超声操作，以评估基因转移的可能性。与传统的成像频率(&lt；10 MHz)不同，高频超声为微循环成像提供了实现精细横向分辨率的手段，并为声波手术提供了高度局部化的压力暴露。具体地说，我们建议开展与声学造影剂高频超声激发相关的全面的理论和实验研究。目前可用的蛋白质、脂肪和聚合物外壳试剂以及我们自己定制的聚合物外壳试剂将进行实验表征，以量化后向散射(散射截面、非线性响应等)、衰减、声速和破坏阈值。将建立理论模型，扩展早期的模型，并将径向响应和毒剂破坏的模拟与实验结果进行比较。这些模型将被用来更好地理解高频超声应用中造影剂的最佳材料特性，并深入了解导致造影剂破坏的物理机制。理论和实验结果将被用于制定成像和信号处理策略，以更好地可视化微循环。从初步的实验和理论工作中获得的知识也将用于优化体内动物实验的声暴露条件。这些造影剂将用于成像兔眼和小鼠胚胎的微循环，并通过声学修饰启动小鼠胚胎的基因导入。动物实验，特别是那些涉及兔眼的实验，将与成像人类疾病直接相关，包括青光眼(美国为200万至300万)、黄斑变性(美国每年新增病例20万例)和原发眼内肿瘤(美国每年新增病例3000例)。例如，带有造影剂的高频超声可以通过评估视神经和睫状体的微循环来帮助诊断青光眼，青光眼是美国导致失明的主要原因。公共卫生相关性这项研究的最终目标是将声学造影剂的使用扩展到更高的频率，以便能够通过声学造影术进行微循环成像和启动基因转染术。我们所产生的知识将有助于设计新的试剂，优化声暴露条件，并最终将导致新的临床应用，如眼病诊断和靶向基因转染。

DESCRIPTION (provided by applicant): The goal of this study is to utilize acoustic contrast agents with high-frequency ultrasound (HFU, > 10 MHz) in order to image microcirculation and initiate gene transfection via sonoporation. Current contrast agents were not designed for these high frequencies. The study will assess two important applications: 1) imaging of slow-flow microvasculature in rabbit eyes and mouse embryos; and 2) the initiation of sonoporation in mouse embryos to assess the potential for gene transfection. Unlike with conventional imaging frequencies (< 10 MHz), HFU provides the means to achieve fine-scale lateral resolution for microcirculation imaging and highly localized pressure exposure for sonoporation. Specifically, we propose undertaking comprehensive theoretical and experimental studies related to HFU excitation of acoustic contrast agents. Currently available protein-, lipid-, and polymer-shelled agents along with our own custom-made, polymer-shelled agents will be characterized experimentally to quantify backscatter (scattering cross section, nonlinear response, etc.), attenuation, speed of sound, and destruction threshold. Theoretical models that extend well-founded earlier models will be developed and simulations of radial response and agent destruction will be compared to experimental results. The models will be utilized to better understand the optimal material properties of contrast agents for HFU applications and to gain insight into the physical mechanisms that lead to the destruction of contrast agents. The theoretical and experimental results will then be used to formulate imaging and signal processing strategies to better visualize microcirculation. Knowledge gained from the initial experimental and theoretical work will also be applied to optimizing acoustic exposure conditions for in vivo animal experiments. The contrast agents will be used to image microcirculation in rabbit eyes and mouse embryos as well as to initiate gene transfection via sonoporation in mouse embryos. The animal experiments, particularly those involving the rabbit eye, will have direct relevance for imaging human diseases including glaucoma (2-3 million in U.S.), macular degeneration (200,000 new cases each year in U.S.), and primary intraocular tumors (3,000 new cases each year in U.S.). For instance, HFU with contrast agents may help diagnose glaucoma, the leading cause of blindness in the U.S., by permitting the assessment of microcirculation in the optic nerve and ciliary body. PUBLIC HEALTH RELEVANCE The ultimate goal of this research is to extend the use of acoustic contrast agents to higher frequencies in order to permit the imaging of microcirculation and the initiation of gene transfection via sonoporation. The knowledge we generate will assist in the design of new agents, optimizing acoustic exposure conditions, and, ultimately, will lead to new clinical applications such as ocular disease diagnosis and targeted gene transfection.