基于超声脉搏波成像的颈动脉弹性成像方法研究

发布时间：2018-06-22 08:00

本文选题：分段式脉搏波成像 + 血管硬度　；参考：《深圳大学》2017年硕士论文

【摘要】：动脉硬化一般起病隐匿,进展缓慢,严重时会导致心血管疾病的发生如心脏病、中风、脑血栓等,心血管疾病现已成为全世界人口死亡的主要原因,因此早期诊断动脉弹性对预防与治疗心血管疾病有着重要意义。动脉脉搏波起始于左心室,作为压力波在动脉树中传播,同时引起管壁的收缩膨胀。临床认为脉搏波速度是反映动脉弹性一个重要指标,是临床评价动脉弹性的金标准。血管在不同位置硬度是不同的,脉搏波速度也不一样,因此需要测量局部血管的脉搏波速度,这样才能更准确的反映血管的力学特性,从而为临床诊断提供可靠的依据。本文的主要目的是利用局部血管处的脉搏波速度定量评估管壁甚至斑块的硬度,为此需要寻找一种能够无创、准确测量局部脉搏波速度的技术。现有的超声脉搏波速度测量技术,如血管回声跟踪技术的可重复性和准确性都较差,而UltraFast极速脉搏波速度测量技术应用范围狭窄。脉搏波成像是目前测量脉搏波速度的新技术,能够捕捉到任意血管位置的脉搏波传播,提供丰富的血管弹性信息,尚未进入临床应用。本文重点探究了超声脉搏波成像这一方法在定量评估血管硬度的临床可行性。本文提出了一种新的成像方法—分段式脉搏波成像,对颈动脉管壁、斑块进行硬度测量,1)首先利用有限元仿真软件COMSOL仿真血管—管壁的流固耦合作用,捕捉管壁上的脉搏波,对脉搏波速度与血管硬度的关系进行了研究,证实了利用脉搏波速度可以定量评估血管硬度;2)对分段式脉搏波成像中的散斑追踪算法进行了研究,选出了一种相对优秀的血管壁位移追踪的算法;利用生物力学测试仪对血管仿体的硬度进行测量,作为金标准,验证了超声脉搏波成像所得的血管管壁硬度的准确性;通过不同的数据处理方式,评估了血管硬度测量时所需的超声系统成像参数;3)目前的超声脉搏波成像技术最主要的做法是通过减少线密度提高帧率,线密度是影响分段式脉搏波成像的一个关键因素,针对此缺陷提出将平面波成像技术应用于分段式脉搏波成像,通过血管仿体实验证实了可行性;4)与深圳市第二人民医院超声科合作,采集了正常人颈动脉与动脉粥样硬化患者相关的临床实验数据,利用分段式脉搏波成像对其硬度进行了计算;对比正常人颈动脉与动脉粥样硬化患者结果,不仅能够明显的区分管壁、斑块的软硬程度,还能区分斑块、管壁的交界位置,与传统血管超声弹性方法相比,灵敏度更高。
[Abstract]:Arteriosclerosis, which usually starts and progresses slowly, can lead to cardiovascular diseases such as heart disease, stroke, cerebral thrombosis and so on. Cardiovascular disease has become the leading cause of death in the world's population. Therefore, early diagnosis of arterial elasticity is of great significance in the prevention and treatment of cardiovascular diseases. The arterial pulse wave originates from the left ventricle and propagates through the arterial tree as a pressure wave, which also causes the contraction and expansion of the wall. Pulse wave velocity is considered as an important index to reflect arterial elasticity and a gold standard for clinical evaluation of arterial elasticity. The hardness of blood vessels is different in different positions and the pulse wave velocities are different. So it is necessary to measure the pulse wave velocities of local blood vessels so as to more accurately reflect the mechanical characteristics of blood vessels and provide reliable basis for clinical diagnosis. The main purpose of this paper is to quantitatively evaluate the hardness of the wall and even plaque by using the pulse wave velocity of the local blood vessel. Therefore, we need to find a non-invasive and accurate technique to measure the local pulse wave velocity. The existing ultrasonic pulse wave velocity measurement techniques, such as vascular echo tracking, have poor repeatability and accuracy, while UltraFast pulse velocity measurement technology has a narrow range of application. Pulse wave imaging is a new technique to measure pulse wave velocity at present. It can capture pulse wave propagation at any position of blood vessel and provide abundant information of vessel elasticity. It has not been applied in clinic. This paper focuses on the clinical feasibility of ultrasonic pulse wave imaging in quantitative evaluation of vascular hardness. In this paper, a new imaging method, segmental pulse wave imaging, is proposed. The hardness of carotid artery wall and plaque is measured. Firstly, the fluid-solid coupling between vessel and wall is simulated by finite element simulation software COMSOL to capture the pulse wave on the wall. The relationship between pulse wave velocity and blood vessel hardness is studied. It is proved that pulse wave velocity can be used to quantitatively evaluate the vascular hardness. (2) the speckle tracing algorithm in segmented pulse wave imaging is studied. A relatively excellent algorithm for tracking the displacement of vascular wall is selected, and the hardness of vascular imitating body is measured by biomechanical testing instrument, which is used as gold standard to verify the accuracy of the hardness of vascular wall obtained by ultrasonic pulse wave imaging. By using different data processing methods, the ultrasonic system imaging parameters needed for vascular hardness measurement are evaluated. (3) the most important method of ultrasonic pulse wave imaging is to increase the frame rate by reducing the linear density. Linear density is a key factor affecting segmented pulse wave imaging. In view of this defect, plane wave imaging technology is applied to segmented pulse wave imaging. The feasibility of the experiment was confirmed by blood vessel phantom test. (4) the clinical data of carotid artery and atherosclerosis patients in normal people were collected in cooperation with ultrasound department of Shenzhen second people's Hospital. The hardness was calculated by segmental pulse wave imaging. Comparing the results of carotid artery and atherosclerotic patients in normal people, not only the wall, the soft and hard degree of plaque, but also the junction of plaque and wall could be distinguished. Compared with the traditional vascular ultrasound elastic method, the sensitivity is higher.
【学位授予单位】：深圳大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R543;TP391.41

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