Measuring arterial material properties using wave-based approaches with ultrasound and computational models

摘要/总结 背景：动脉硬化的增加与脑损伤的指标有关，包括 通过磁共振评估存在白色高信号、梗死和脑萎缩 成像（MRI）。当血管失去机械吸收脉动流影响的能力时， 脉动性被传递到脑中的脉管系统，导致脑组织中的有害变化。 了解超声测量中心导管的粘弹性机械特性的影响（例如， 颈动脉）相对于MRI测量的脑健康指标可能会导致一个非常重要的工具， 预测和管理大脑功能的变化。该研究项目旨在解决这些未得到满足和 迫切需要开发准确和可平移的超声测量技术， 粘弹性动脉机械性能和评估与脑结构变化的关联。 方法：超声是血管评价的一线成像方式，但大多数临床扫描仪不具备这一条件 具有以精确的方式评估血管的弹性或粘弹性机械特性的能力， 具有高时间分辨率的定量方式。在第一轮拨款中，我们开发了一种超声波- 基于称为动脉弥散超声振动测量（ADUV）的方法，该方法利用声辐射力， 在动脉壁中刺激高频（200-1500 Hz）波，然后进行高帧率超声， 测量用于表征动脉粘弹性机械特性的波动。 然而，我们的研究表明，ADUV的几个方面可以进一步改进，然后再用于 每天在诊所里。在这些改进中，增加了波动信噪比， 用超声波精确测量血管几何形状，并改进我们的反演， 分类框架。通过这些改进的ADUV方法，我们将评估粘弹性 颈动脉的性质与大脑的健康有关， 形态学数据凭借强大的合作团队，包括心血管医学，放射学， 超声工程，波导建模，逆问题，数据简化和分类，我们将带来 ADUV更接近于广泛的翻译，具有以下具体目标： 目标1）优化ADUV以提高运动测量质量，使其更准确和精确 力学性能评价 目的2）开发用于估计动脉机械特性的高级数学模型， 疾病状态的分类。 目的3）将颈动脉粘弹性的ADUV测量与脑MRI指标相关联 患者的健康。

ABSTRACT/SUMMARY Background: Increased arterial stiffness has been associated with indicators of damage to the brain including presence of white matter hyperintensity, infarctions, and brain atrophy as assessed with magnetic resonance imaging (MRI). When vessels lose their ability to mechanically absorb the effects of pulsatile flow, that pulsatility is transmitted to the vasculature in the brain leading to deleterious changes in the brain tissue. Understanding the effect of ultrasound measured viscoelastic mechanical properties of central conduit (e.g., carotid) arteries relative to MRI measured brain health indicators could result in a very important tool for predicting and managing changes in brain function. This research project aims to address these unmet and critical needs to develop techniques for the accurate and translatable ultrasound measurement of viscoelastic arterial mechanical properties and evaluate associations with structural changes in the brain. Methods: Ultrasound is a first-line imaging modality for vascular evaluation, but most clinical scanners do not have the ability to evaluate the elastic or viscoelastic mechanical properties of vessels in an accurate, quantitative manner with high temporal resolution. In the first cycle of this grant, we developed an ultrasound- based method called arterial dispersion ultrasound vibrometry (ADUV) that utilizes acoustic radiation force to stimulate high-frequency (200-1500 Hz) waves in the arterial wall, followed by high frame rate ultrasound to measure the wave motion, which is used to characterize arterial viscoelastic mechanical properties. However, our research revealed that several aspects of ADUV could be further improved before being used on a daily basis in the clinic. Among these improvements are increasing the wave motion signal-to-noise ratio, making precise measurements of the vessel geometry with ultrasound, and improving our inversion and classification frameworks. With these improved ADUV methods, we will evaluate how the viscoelastic properties of the carotid artery are associated with the health of the brain as judged using MRI brain morphology data. With the strong collaborative team including expertise in cardiovascular medicine, radiology, ultrasound engineering, waveguide modeling, inverse problems, data reduction and classification, we will bring ADUV closer to widespread translation with the following Specific Aims: Aim 1) Optimize ADUV to enhance motion measurement quality for more accurate and precise mechanical property estimation. Aim 2) Develop advanced mathematical models for estimation of arterial mechanical properties and classification of disease state. Aim 3) Correlate ADUV measurements of carotid artery viscoelasticity with MRI indicators of brain health in patients.