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

摘要 提出的R21工作的目标是开发和演示一种新型的高速(10赫兹)多片 MRI动态采集和基于模型的分析技术用于量化椎体的生物力学特性 脑血管。这一新方法测量T1加权流入波动(与血液相关 血流/速度)在大的动静脉血管中。然后是基于流体力学模型的分析 用于检测被测速度波形之间的频率相关衰减和相位 从血管节段的近端和远端可以表征生物物理 这些节段的特性包括血管阻力、电感和顺应性。这些高时态 信号与结构磁共振血管造影术相结合以提供血管属性的空间图 和拓扑学。 我们认为，这些可量化的生物力学和数学参数可以与大脑 血管疾病，因为这些疾病直接反映血管的僵硬和流动阻力等特性。 这些方法的发展具有重要的临床意义，对定量评估 脑血管生理学在血管疾病的背景下，如高血压、狭窄和 卒中。作为此方法的概念验证，并初步调查此方法的敏感性，此 将应用这项技术来表征两组慢性阻塞性肺疾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组的比较。这个 该项目的具体目标是： 目的1.优化快速磁共振动脉顺应性成像方法。 目的2.对慢性阻塞性肺疾病患者进行高速磁共振动脉顺应性成像的概念验证 高血压(HT)和单纯收缩期高血压(ISH)患者与年龄匹配的比较 血压正常(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厚的变化很敏感 使用我们建议的高速MR动脉顺应性可以可靠地测量HT和ISH患者的血压 测绘方法。 假设2.高血压和ISH患者将表现出阻力(僵硬)增加和电容减少 (合规性)与NT控制相比。这些变化在ISH组中会更大。充满活力的大脑 HT和ISH患者的自动调节指数(DCAI)均受到损害。

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.