Imaging and modeling the biomechanics of large cerebral blood vessels using high-speed dynamic MRI

摘要 这项建议的R21工作的目标是开发和展示一种新型的高速（10 Hz）多切片 动态MRI采集和基于模型的分析技术，以量化 脑血管这种新方法测量T1加权流入波动（与血液相关 流量/速度）。基于流体力学模型的分析， 应用于检查频率相关阻尼和测量速度波形之间的相位 从血管段的近端和远端的测量允许表征生物物理特性 这些节段的特性包括血管阻力、电感和顺应性。这些高时间 信号与结构MRI血管造影术相结合，以提供血管特性的空间图 和拓扑学。 我们相信这些可量化的生物力学和数学参数可以与大脑 血管疾病，因为这些直接反映了血管的刚性和流动阻力等特性。 这些方法的发展对定量评估具有重要的临床意义。 在血管疾病如高血压、狭窄和脑血管病风险的背景下， 中风作为这种方法的概念验证，并初步调查这种方法的灵敏度， 技术将被应用于表征两组慢性脑血管病患者的脑血管特性。 高血压和单纯收缩期高血压与年龄匹配的正常血压对照相比。的 该项目的具体目标是： 目标1.优化高速MR动脉顺应性标测方法。 目标2.证明慢性患者中高速MR动脉顺应性标测的概念验证 高血压（HT）和单纯收缩期高血压（ISH）患者，并与年龄匹配的 正常血压（NT）健康对照。 我们假设： 假设1.血管阻力和顺应性的测量对肥大性变化敏感， HT和ISH患者，可以使用我们提出的高速MR动脉顺应性可靠地测量 映射方法 假设2. HT和ISH患者将表现出电阻增加（僵硬）和电容降低 （合规性）与NT对照相比。ISH组的这些变化更大。动态大脑 自动调节指数（dCAI）在HT和ISH中都将受损。

ABSTRACT The objective of this proposed R21 work is to develop and demonstrate a novel high-speed (10Hz) multi-slice dynamic MRI acquisition and model-based analysis technique to quantify the biomechanical properties of cerebral blood vessels. This novel approach measures T1-weighted inflow fluctuations (related to blood flow/velocity) in large arterial and venous blood vessels. Fluid mechanics model-based analysis is then applied to examine the frequency-dependent dampening and phase between velocity waveforms measured from proximal and distal ends of blood vessel segments allows the characterization of the biophysical properties of these segments including vascular resistance, inductance, and compliance. These high temporal signals are combined with structural MRI angiography to provide a spatial map of the blood vessel properties and topology. We believe that these quantifiable biomechanical and mathematical parameters can be linked to cerebral vascular diseases, since these directly reflect properties such as the rigidity and flow resistance of the vessels. The development of these methods has significant clinical implications toward quantitative assessment of cerebral vascular physiology in the context of vascular disorders such as hypertension, stenosis, and risk of stroke. As a proof-of-concept of this approach, and to initially investigate the sensitivity of this method, this technique will be applied to characterize the cerebral vascular properties of two groups of patients with chronic hypertension and isolated systolic hypertension in comparison to age-matched normotensive controls. The specific aims of this project are: Aim 1. Optimize methods for high-speed MR arterial compliance mapping. Aim 2. Demonstrate proof-of-concept for high-speed MR arterial compliance mapping in chronic hypertensive (HT) and isolated systolic hypertension (ISH) patients and compared to age-matched normotensive (NT) healthy controls. We hypothesize that: Hypothesis 1. Measurements of vascular resistance and compliance is sensitive to hypertrophic changes in HT and ISH patients and can be reliably measured using our proposed high-speed MR arterial compliance mapping approach. Hypothesis 2. HT and ISH patients will show increased resistance (stiffness) and decreased capacitance (compliance) compared to NT controls. These changes will be larger in the ISH group. The dynamic cerebral auto-regulation index (dCAI) will be impaired in both HT and ISH.