Mechanisms of Image Quality Improvement via Harmonic Imaging

描述（由申请人提供）：尽管超声谐波成像已被广泛接受，但其成像质量优于传统超声成像的机制尚不清楚。文献中提出了三种这样的机制，这些机制已经在水箱实验中得到了证明。然而，这些机制对体内成像的意义仍然不明确。我们假设，阐明这些机制可以优化谐波信号的产生，并进一步提高图像质量。我们开发了强大的模拟工具，能够在各种介质中传播非线性波，包括漫射散射体和层状和像差介质。这些模拟不仅限于前向传播波，而且可以模拟来自漫射散射点的多径反射和来自分层和像差介质的混响。我们还开发了体内实验技术来单独表征每种机制。我们已经开发了这些技术，用于能够实时三维成像的新型1728通道波束形成系统。我们提出了一系列的实验，旨在分离和确定每个机制在体内的贡献。这些实验是在志愿者和患者的膀胱和肝脏中使用1728通道波束形成系统进行的。此外，我们提出了新的模拟研究，通过我们的体内实验，能够三维非线性波传播。基于我们的模拟和临床研究，我们提出了谐波信号生成的优化方法，并进行了第二轮临床研究，在体内观察优化后的谐波成像方法。公共卫生相关性：在本提案中，我们讨论超声谐波成像的物理机制。关键问题是，在对人体进行成像时，人们对这些机制知之甚少。我们建议扩大我们对这些机制的认识，并在此基础上改进谐波成像方法。

DESCRIPTION (provided by applicant): Despite the widespread acceptance of harmonic imaging in ultrasound, the mechanisms by which image quality is improved over conventional ultrasonography are not well understood. Three such mechanisms have been proposed in the literature, and these mechanisms have been demonstrated in water tank experiments. However, the significance of these mechanisms remain ambiguous for in vivo imaging. We hypothesize that elucidation of these mechanisms can lead to optimization of harmonic signal generation and yield further image quality improvement. We have developed powerful simulation tools capable of propagating nonlinear waves through various media including diffuse scatterers and layered and aberrating media in 3-D. These simulations are not limited to forward propagating waves, and can model mul- tipath reflections from diffuse scattering sites and reverberations from layered and aberrating media. We have also developed in vivo experimental techniques for characterizing each mechanism individually. We have developed these techniques to be used on a novel 1728 channel beamforming system capable of real-time 3-D imaging. We propose a series of experiments designed to separate and determine the contribution of each mechanism in vivo. These experiments are performed in the bladders and livers of volunteers and patients using the 1728 channel beamforming system. In addition, we propose novel simulation studies, informed by our in vivo experimentation, that are capable of 3-D nonlinear wave propagation. Based on our simulations and clinical studies, we propose optimization methods of harmonic signal generation and a second round of clinical studies to observe the optimized harmonic imaging methods in vivo. PUBLIC HEALTH RELEVANCE: In this proposal, we address the physical mechanisms of harmonic imaging in ultrasound. The key problem is that these mechanisms are poorly understood when imaging the human body. We propose to expand our knowledge of these mechanisms and improve harmonic imaging methods based on this knowledge.