【作者】 李晓；

【导师】 刘晓晟；

【作者基本信息】 上海交通大学 ， 影像医学与核医学， 2017， 硕士

【摘要】 第一部分:基于三维影像数据应用CFD研究颈动脉粥样硬化斑块形成与局部血流动力学的关系目的:基于三维对比增强磁共振血管造影(contrast enhanced-magnetic resonance angiography,CE-MRA)图像,运用计算流体力学(computational fluid dynamics,CFD)方法,比较正常在体颈动脉斑块易发部位与血管其它部位壁面剪切力(wall shear stress,WSS)、压力、血流速度及血流状态的差异,探讨颈动脉粥样硬化斑块形成与局部血流动力学因素的相关性。材料和方法:选取16根由颈动脉磁共振成像证实的无明显动脉粥样硬化斑块的颈动脉纳入研究,并收集其CE-MRA原始图像用于血管三维建模。应用CFD方法建模分析正常颈动脉斑块易发部位(颈动脉窦)和血管其它部位(颈总动脉远端及颈内动脉远端)WSS、压力、血流速度及血流状态的分布情况,并采用方差分析方法对不同部位间的差异进行统计学分析。结果:CFD分析发现颈动脉窦处WSS及血流速度均小于颈总动脉远端(P=0.011,P<0.001)和颈内动脉远端(P<0.001,P<0.001),且于颈动脉窦处形成涡流。而颈动脉窦处平面内压力差大于颈总动脉远端(P<0.001)及颈内动脉远端(P=0.005)。结论:应用CFD方法分析发现正常颈动脉窦处具有低WSS、高平面内压力差、低血流速度及形成涡流的血流动力学特征,与该部位易发生动脉粥样硬化斑块有关。第二部分:基于三维影像数据应用CFD研究狭窄颈动脉及狭窄修复后颈动脉局部血流动力学参数的变化目的:运用血管表面修复方法模拟颈动脉粥样硬化(carotid atherosclerosis,CAS)斑块发生前的状态,比较斑块发生前后颈动脉局部血流动力学的变化,探究局部血流动力学因素与CAS斑块形成及发展的关系。材料和方法:选取16根由颈动脉磁共振成像证实的单发于颈动脉窦处动脉粥样硬化狭窄的颈动脉纳入研究,并收集其三维对比增强磁共振血管造影(contrast enhanced-magnetic resonance angiography,CE-MRA)原始图像用于三维血管重建。运用血管表面修复方法修复狭窄颈动脉以模拟正常血管。应用计算流体力学(computational fluid dynamics,CFD)方法建模分析比较狭窄修复后颈动脉窦和血管其它部位、狭窄修复前后颈动脉窦、修复后颈动脉窦和修复前狭窄血管的斑块上下游壁面剪切力(wall shear stress,WSS)、压力、血流速度及血流状态的差异。结果:CFD分析发现狭窄修复后血管的颈动脉窦相比于其它部位(颈内动脉内侧与颈动脉窦相对处、颈总动脉内外侧及颈内动脉内外侧)具有低WSS(4.66 vs.14.30,7.05,6.51,8.71,12.20Pa,P<0.05)及低血流速度(0.43 vs.1.20,0.79,0.94,1.29,0.91m/s,P<0.05)的特征,且形成涡流。狭窄修复后血管的颈动脉窦水平压力差显著高于颈总动脉及颈内动脉水平(202 vs.37,143 Pa,P<0.05)。相较于狭窄修复后血管的颈动脉窦,狭窄血管斑块上游WSS更低(3.44 vs.4.66Pa,P<0.05)而斑块下游WSS与之相仿(5.16 vs.4.66Pa,P=0.87);相较于狭窄修复后血管的颈动脉窦,狭窄血管斑块上下游血流速度与之相仿(0.43,0.21 vs.0.43m/s,P=0.76,P=0.36);斑块上下游均形成涡流。结论:血管表面修复法可一定程度上模拟正常血管的形态,将该方法用于模拟分析颈动脉斑块发生前后的随访性研究是一种较方便、经济及简单的方法。CAS易发部位具有低WSS、高平面内压力差、低血流速度及涡流形成的血流动力学特征,与该部位易发动脉粥样硬化斑块有关。此外,斑块上下游具有与颈动脉窦相仿的血流动力学环境,与斑块进展有关。第三部分:基于三维影像数据应用CFD分析颈动脉粥样硬化斑块破裂与局部血流动力学的关系目的:运用血管表面修复方法修复颈动脉粥样硬化(carotid atherosclerosis,CAS)破裂斑块,模拟斑块破裂前的状态,分析斑块易破裂部位周围血流动力学特征,探讨可能导致斑块破裂的血流动力学因素。材料和方法:选取13根由颈动脉磁共振成像证实的含破裂动脉粥样硬化斑块的颈动脉纳入研究,并收集其三维对比增强磁共振血管造影(contrast enhanced-magnetic resonance angiography,CE-MRA)原始图像进行血管三维重建。运用血管表面修复方法将颈动脉破裂斑块修复成未破裂斑块,模拟其破裂前的状态。计算流体力学(computational fluid dynamics,CFD)建模分析斑块易破裂部位及斑块其它部位、斑块破裂前后局部血流动力学的特征。结果:13例斑块破裂位置均位于斑块近心端。修复后斑块近心端较斑块其它部位壁面剪切力(wall shear stress,WSS)高(160 vs.92 Pa,P<0.0001),压力高(18070vs.10295Pa,P<0.0001)及血流速度高(11.46 vs.7.5m/s,P<0.0001)。易破裂斑块形成高表面压力差,斑块破裂后,表面压力差降低(35 vs.8065Pa,P<0.0001)破裂部位WSS、压力及血流速度均降低(1.63 vs.160Pa,7023 vs.18070Pa,1.56 vs.11.46m/s,P<0.0001)。结论:血管表面修复法可一定程度上反映斑块破裂前的形态,将该方法用于模拟分析斑块破裂前后的随访性研究是一种较方便、经济及简单的方法。易破裂斑块近心端局部呈现高WSS、高压力、高血流速度及高斑块表面压力差血流动力学特征,与斑块近心端易于发生破裂有关。更多还原

【Abstract】 Part I: Association Between Formation of Carotid Atherosclerotic Plaque and Local Hemodynamics Using CFD Based on Three-dimensional ImagesObjective: To compare the difference of wall shear stress(WSS),pressure,blood flow velocity and flow pattern between plaque-prone area and other areas in normal carotid artery in vivo,using computational fluid dynamics(CFD)based on three-dimensional contrast enhanced-magnetic resonance angiography(CE-MRA)images and to discuss the association between formation of carotid atherosclerotic plaque and local hemodynamic factors.Materials and Methods: Sixteen carotid arteries without atherosclerotic plaque confirmed by carotid MR imaging were enrolled in our study.Original CE-MRA images were obtained for three-dimensional reconstruction.CFD analysis was then performed to estimate WSS,pressure,blood flow velocity and flow pattern in atherosclerosis-prone(sinus)and other areas(distal common carotid artery and distal internal carotid artery)in normal carotid artery.One-way analysis of variance was conducted to analyze differences among these areas.Results: CFD analysis revealed that WSS and velocity were significantly lower in sinus compared to distal common carotid artery(CCA)(P=0.011,P<0.001,respectively)and distal internal carotid artery(ICA)(P<0.001,P<0.001),and formed a vortex in sinus.While in-plane pressure difference was significantly higher in sinus compared to distal CCA(P <0.001)and distal ICA(P =0.005).Conclusion: Hemodynamic environment in sinus of normal carotid artery assessed using CFD analysis which appeared to be with lower WSS,higher in-plane pressure difference,lower velocity and formed vortex.These characterizations might facilitate the formation of atherosclerotic plaque.Part II: CFD Study of Local Hemodynamic Parameters Variation in Stenotic and Stenosis-repaired Carotid Arteries Based on Three-dimensional ImagesObjective: To study the variation before and after the formation of carotid atherosclerotic(CAS)plaque using vessel surface repaired method simulating normal carotid artery and to discuss the association between formation and development of carotid atherosclerotic plaque and local hemodynamic factors.Materials and Methods: Sixteen carotid arteries with sinus atherosclerotic plaque only confirmed by carotid MR imaging were enrolled in our study.Original three-dimensional(contrast enhanced-magnetic resonance angiography)CE-MRA images were obtained for three-dimensional reconstruction.The stenotic segments of carotid arteries were repaired by vessel surface repaired method to simulate normal carotid arteries.Computational fluid dynamics(CFD)analysis was performed to estimate wall shear stress(WSS),pressure,blood flow velocity and flow pattern in sinus and other areas in stenosis-repaired carotid artery,sinus before and after repaired,sinus in stenosis-repaired carotid artery and upstream and downstream of stenosis in stenotic carotid artery.Results: Compared with other areas(inner lateral internal carotid artery opposite to sinus,inner and outer lateral at common carotid artery and internal carotid artery)in stenosis-repaired artery,sinus demonstrated significantly lower WSS(4.66 vs.14.30,7.05,6.51,8.71,12.20 Pa,P<0.05,respectively)and lower velocity(0.43 vs.1.20,0.79,0.94,1.29,0.91m/s,P<0.05,respectively),and formed a vortex.Compared with common carotid artery level and internal carotid artery level in stenosis-repaired artery,sinus demonstrated higher in-plane pressure difference(202 vs.37,143 Pa,P <0.05,respectively).Compared with carotid sinus in stenosis-repaired carotid artery,the WSS in the upstream of stenosis in stenotic carotid artery was lower(3.44 vs.4.66 Pa,P<0.05)while in the downstream area was similar(5.16 vs.4.66 Pa,P=0.87),both upstream and downstream of stenosis were demonstrated similar velocity to carotid sinus in stenosis-repaired carotid artery(0.43,0.21 vs.0.43m/s,P=0.76,P=0.36,respectively).Both the upstream and downstream of stenosis formed vortex.Conclusion: Using the vessel surface repaired method to simulating normal vessel as follow up study of carotid plaque formation is feasible,economical,and simple.Atherosclerosis-prone areas harbor a hemodynamic environment characterized by lower WSS,higher in-plane pressure difference,lower velocity and formed vortex,favoring the formation of atherosclerosis.The hemodynamic characters of upstream and downstream may relate to the progress of atherosclerotic plaque.Part III: Association Between Rupture of Carotid Atherosclerotic Plaque and Local Hemodynamics Using CFD Based on Three-dimensional ImagesObjective: To analyze the hemodynamic characteristics in prone-rupture area of carotid atherosclerotic(CAS)plaque using vessel surface repaired method simulating pre-rupture plaque and to explore the possible hemodynamic factors lead to plaque rupture.Materials and Methods: Thirteen carotid arteries with ruptured atherosclerotic plaques confirmed by carotid MR imaging were enrolled in our study.Original three-dimensional contrast enhanced-magnetic resonance angiography(CE-MRA)images were obtained for three-dimensional reconstruction.The rupture area of carotid plaque was repaired by vessel surface repaired method to simulate pre-rupture plaque.Computational fluid dynamics(CFD)analysis was performed to estimate hemodynamic factors in prone-rupture area,other area,before and after rupture.Results: All of the thirteen rupture sites were located in proximal side of plaque.In rupture-repaired carotid plaque,compared with other area,the proximal side of plaque demonstrated significantly higher wall shear stress(WSS)(160 vs.92 Pa,P<0.0001),higher pressure(18070 vs.10295 Pa,P<0.0001)and larger velocity(11.46 vs.7.5m/s,P<0.0001).And form a high pressure difference on prone-rupture plaque.The WSS,pressure and velocity was lower(1.63 vs.160 Pa,7023 vs.18070 Pa,1.56 vs.11.46m/s,P<0.0001,respectively)when the plaque was rupture.Conclusion: Using the vessel surface repaired method to simulating pre-rupture plaque as follow up study of carotid plaque rupture is feasible,economical,and simple.The proximal side of pre-rupture plaque harbor a hemodynamic environment characterized by higher WSS,higher pressure,higher velocity and high pressure difference across plaque may favoring the rupture of plaque.更多还原