Evaluation of Regional Arterial Wall Elasticity and Intra-atheromatous Physical Property by Novel High-Resolution Doppler Method -Quantitative Relationship between Multiple Risk Index and Physical Property of Arterial Wall in the Group Medical Examination

在本项目中，我们进一步将无创高分辨率诊断方法“分期追踪法”改进为临床模式，测量动脉粥样硬化的区域性、十微米级病理变化，并将该方法应用于群体体检。我们还研究了Framingham报告中提出的每个动脉粥样硬化危险因素或多重危险指数与颈动脉病理病变以及动脉粥样硬化内斑块物理性质之间的关系。以下是本项目的成果：我们能够精确地评估动脉壁厚度的区域硬化变化，心脏周期内壁厚的瞬时变化，适当的区域弹性刚度不仅在整个壁厚上，而且在壁上每10微米厚度层上。这些测量可在5分钟内完成，成为真正的常规诊断方法。动脉硬化最早的变化是固有壁的改变，而不是以往报道认为的动脉壁增厚。利用这种方法，我们可以评估动脉粥样硬化斑块内部的物理性质。斑块的基本物理特征表明，较硬的帽表面覆盖了内部更柔顺的材料。通过控制风险指数，粥样斑块的物理性质在相对较短的几周内发生了变化。动脉粥样硬化斑块的稳定性被认为是急性冠脉综合征的关键因素。这里开发的非侵入性多普勒技术提供了斑块上每一层的粘弹性值和物理稳定性的信息。新型多普勒方法可用于临床集体检查中的保健教育，并可通过药物治疗明确局部动脉粥样硬化病变的变化情况。

In this project, we further improved the non-invasive high-resolution diagnostic method "Phased Tracking Method" for the clinical modality to measure regional, tenth micron-order pathological change of the arterioatherosclerosis, applying the method for the group medical examination. We also examined relationships between each areteriosclerotic risk factor or the multiple risk index proposed in Framingham report and the pathological lesion at carotid artery as well as the intra-atheromatous physical property of the carotid arterial plaque.Followings are results form this project ;1. We become able to evaluate precisely the regional sclerotic change of the arterial wall thickness, the instantaneous change in the wall thickness during the cardiac cycle, proper regional elastic stiffness snot only across the entire wall thickness but also of each tenth-micron thickness layer across the wall. These measurements could be accomplished within 5 minutes and become real routine diagnostic method.2. The earliest change of the arteriosclerosis was the change in the proper wall, not the thickening of the wall as believed in the previous report.3. Using this method, we can evaluate the physical nature inside the atheromatous plaque. The basic physical feature of the plaque suggested that the stiffer cap covered superficially the much compliant material interior.4. The physical nature of the atheromatous plaque changed within relatively short period of several weeks by the control of the risk index.The stability of the atheromatous plaque has been suggested to be the key factor of the acute coronary syndrome. The non-invasive Doppler technique developed here supplies the information of the visco-elastic value at each layer across the plaque and physical stability. The novel Doppler method would be useful for the health care education in the group clinical examination and clarify the changing aspect of the regional atheromatous lesion through the medical therapy.