冠脉血管三维建模与血液动力学研究

发布时间：2018-04-20 07:05

本文选题：冠脉造影 + 血管提取　；参考：《吉林大学》2017年硕士论文

【摘要】：目前,心脑血管疾病已然成为人类健康的主要“杀手”,尤其是发生在冠状动脉血管上的相关疾病更是成为健康的主要威胁。因此,若将生物医学图像技术处理与计算血液流体动力学紧密结合作为冠脉血管疾病的辅助决策是非常必要的,不仅通过建立冠脉血管三维图像可为医学工作者提供直观、形象的病症分析,而且通过分析血管内血液与弹性管壁相互耦合效应可为医学工作者研究相关疾病病理提供理论基础与研究方法。在生物医学图像技术处理过程中可以利用不同造影角度形成的二维血管图像重构三维冠脉图像正确反应出血管的形状、病变程度、量化参数等信息,从而方便医学工作者直观、精确地对血管相关病变作出判断。针对噪声与低对比度影响冠脉造影血管提取精度的难题,本课题在充分综合冠脉造影图像自身特性后,根据冠脉造影图像序列对血管进行提取,通过区分冠脉造影图像序列中冠脉与背景点灰度变化趋势,采用高通频域滤波器对冠脉血管进行增强处理并降低背景点的噪声。然后,采用形态学的改进方法与阈值的相对比较继续增强血管、降低噪声影响并提取冠脉血管;利用形态学细化方法对已较精确提取出的冠脉血管进行骨架提取,并运用“8-链码”进行数学表达。然后,采用垂直线提取方法对冠脉血管直径进行提取;针对冠脉血管的三维建模,首先研究了造影系统的成像原理、造影角度、空间坐标变换以及三维重建所需参数,然后基于已知不同造影角度的冠脉造影图像平面上的血管骨架离散点求解出冠脉三维骨架离散点,随后,运用B样条拟合并插值出更多的三维骨架离散点,使血管三维骨架的可视化具有连续性。在判断冠脉血管具体病变的同时,也要通过计算血液流体动力学来研究冠脉血管相关病变的发病机理,这样才能为冠脉血管疾病的治疗起到辅助决策作用。其中,从冠脉血管三维建模中得到的有关血管的形状与具体量化参数等信息对计算血液流体动力学的研究起到至关重要作用。针对冠状动脉血管中血液流体力学研究,选取三种具有代表性的血管模型:锥形血管,局部狭窄血管,异径血管。根据流体弹性力学基本理论知识,简化流动血液的Navier-stokes方程和血管壁运动方程。运用相容拉格朗日-欧拉法建立血液流动与血管壁运动的耦合条件方程,并基于脉搏波波形、血管的形状,建立流动状态下血液速度的数学表达,结合血管壁运动方程推导血管壁所受压力与血管壁变形表达式。血液在异径血管中流动时由于其特性阻抗的存在会产生压力降,因此,异径血管各血管段的压力降是通过求取各管段的特性阻抗以及脉搏波速得到。本课题通过血管具体实例,分析了脉搏波在一个心动周期内血管相关的参数:半径、厚度、弹性模量,不同血压,压力降以及血管不同的狭窄程度对血管壁所受应力与变形的影响。为了验证理论部分的工作,采用Ansys有限元软件中的流固耦合模块,在给定特定值下进行数值模拟,并与理论部分比较,从而验证理论解的正确性。
[Abstract]:At present, cardiovascular and cerebrovascular diseases have become the main "killer" of human health, especially the related diseases that occur on the coronary arteries, which are the major threats to health. Therefore, it is necessary to cooperate with the calculation of the biomedical image technology and the calculation of blood fluid dynamics closely to assist the decision-making of coronary vascular disease. Not only can the three-dimensional image of coronary artery be established to provide medical workers with intuitionistic and visualized disease analysis, but also through the analysis of the interaction between the blood and the elastic tube wall in the blood vessel, it can provide the theoretical basis and research method for the medical workers to study the related diseases pathology. The reconstruction of three-dimensional coronary images with different angiographic images correctly reacts the shape of the blood vessel, the degree of disease and the quantitative parameters, so that it is convenient for the medical workers to judge the vascular related lesions accurately and intuitively. After fully integrating the characteristics of coronary angiography images, the blood vessels are extracted according to the coronary angiography image sequence. By distinguishing the trend of coronary and background points in the coronary angiography image sequence, high pass frequency filter is used to enhance the coronary vessels and reduce the noise of the back spots. Then, the morphological improvement side is used. The relative comparison between the method and the threshold value continues to strengthen the blood vessels, reduce the noise influence and extract the coronary vessels, and use the morphological thinning method to extract the coronary vessels which have been extracted accurately, and use the "8- chain code" for mathematical expression. Then, the vertical line extraction method is used to extract the diameter of the coronary vessels. The imaging principle of contrast system, the contrast angle, the spatial coordinate transformation and the parameters needed for 3D reconstruction are first studied. Then, the discrete points of the coronary artery are solved based on the discrete points of the vascular skeleton on the coronary angiography image plane with different contrast angles. Then, the B spline is used to interpolate more three. The visualization of vascular three-dimensional skeleton is continuous. In judging the specific coronary artery disease, it is also necessary to study the pathogenesis of coronary vascular related diseases by calculating the blood fluid dynamics, so as to help the treatment of coronary artery disease. Information about the shape of the blood vessels and the specific quantized parameters obtained in the model play an important role in the study of blood fluid dynamics. For the study of blood hydrodynamics in the coronary arteries, three representative vascular models are selected: conical vessels, local narrow vessels, and different diameter vessels. According to the elastic mechanics of fluid This theoretical knowledge simplifies the Navier-stokes equation of the flowing blood and the motion equation of the blood vessel wall. By using the compatible Lagrange Euler method, the coupling condition equation of blood flow and the movement of blood vessel wall is established. Based on the waveform of the pulse wave and the shape of the blood vessel, the mathematical expression of the blood velocity under the flow state is established, and the blood is derived from the equation of movement of the blood vessel wall. The pressure drop of the blood vessel wall is caused by the characteristic impedance of the blood in the different diameter vessels. Therefore, the pressure drop of the various vascular segments of the different diameter vessels is obtained by obtaining the characteristic impedance and the pulse wave velocity of each section of the vessel. Blood vessel related parameters in the dynamic cycle: radius, thickness, modulus of elasticity, the influence of different blood pressure, pressure drop and different degree of blood vessel on the stress and deformation of blood vessel wall. In order to verify the work of the theoretical part, the flow and solid coupling module in Ansys finite element software is used to simulate the value under given value and to the theory department. A comparison is made to verify the correctness of the theoretical solution.

【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP391.41

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