【作者】 郭健；

【导师】 唐达林；

【作者基本信息】 东南大学 ， 生物医学工程， 2018， 硕士

【摘要】 心血管疾病是人类健康的头号杀手。其中大部分临床事件的发生如急性心脏病、心绞痛以及中风都与动脉粥样硬化过程有着密切的联系。随着大量有关动脉粥样硬化易损斑块增长与破裂研究的开展,越来越多的证据表明力学因素在易损斑块的增长与破裂过程中扮演着重要的角色。研究人员引进了多种基于医学多模态影像的计算生物力学仿真模型以求理解斑块增长和破裂的机理,并为临床诊断提供更多有用的信息。由于易损斑块的结构复杂性,成分多样性,三维流固耦合易损斑块模型的搭建及求解需要大量的时间,这也限制了将生物力学模型应用于临床辅助诊疗的可能性。二维模型虽然大大减少了建模及求解时间,以三维流固耦合模型作为金标准,二维模型的精度不足以满足临床要求。因此,本文引入一种三维薄片模型作为三维流固耦合模型的近似,探究三维薄片模型替代三维流固耦合模型以及应用三维薄片模型于冠脉斑块增长预测分析和临床应用的可行性。本文采用已有的四组病人的初访(T1)及随访(T2)数据,包括血管内超声图像(IVUS)以及血管造影数据搭建了8个三维流固耦合模型及385个三维薄片模型,提取两种模型的斑块壁面应力、斑块壁面应变及壁厚进行对比分析,确定三维薄片模型替代三维流固耦合模型产生的误差。同时本文选取壁厚增长为斑块增长的度量,分别研究比较了两种模型计算得到的应力、应变及壁厚三组力学影响因子与斑块增长的相关性及其差异。本文还进一步对力学模型中的周向收缩率、轴向拉伸过程以及循环弯曲对两种模型计算结果带来的影响进行了仔细的研究。结果表明,三维薄片模型与三维流固耦合模型的平均壁面应力与应变的差异均小于10%(应力:9.1%;应变:8.4%)。同时,两组模型的斑块增长与影响因子的相关性也体现出了一致性(正相关负相关结论相同率:87.5%).。从时间成本考虑,三维薄片模型将构造三维流固耦合模型的10-15天压缩至数个小时,在保证一定精度的前提下,大大缩短了模型建模与求解的时间,为生物力学模型应用于临床诊断辅助分析提供了可能性。三维薄片模型仍需大量的患者数据以获得进一步的验证。更多还原

【Abstract】 Cardiovascular disease(CVD)is the leading cause of death in the world.Considerable research has been done linking various risk factors to plaque progression and rupture which often lead to drastic clinical events such as heart attack and stroke.There has been evidence indicating that mechanical stress and strain may play an important role in plaque progression.Researchers have proposed various image-based computational biomechanical models to understand the mechanisms governing plaque progression and rupture and try to provide more useful information for clinical screen strategy.Due to the complexity of plaque structure and composition,3D fluid-structure interaction(FSI)plaque model construction is extremely time-consuming and making 3D models is near impossible for clinical implementations.2D structure-only model is easy to make,but its stress/strain predictions are not good enough to serve as approximation to 3D solutions.In this study,an in vivo IVUS based 3D Thin-Wall(TW)model was developed to approximate 3D FSI model for plaque progression investigation and potential clinical implementations.Eight 3D FSI models and 385 3D thin-walled models based on IVUS image and X ray data at baseline(T1)and follow-up(T2)were constructed in this thesis using existing data to extract plaque wall stress(PWS),strain(PWSn),and wall thickness(WT)values for analysis.Results on matched lumen nodes from TW and FSI models were compared to investigate their differences.For progression analysis,slices at baseline(T1)and follow up(T2)were paired.Plaque progression was measured by wall thickness increase(WTI)defined as WT at T2 – WT at T1.Correlation results using FSI models and TW models were compared.Moreover,impact of circumference shrinkage,pre-stretching and bending on results from FSI and TW models was investigated.Results from the 385 TW models and 8 FSI models for the 4 patients indicated that the differences of mean stress and strain values were less than 10%(stress error 9.1%;strain error 8.4%).Plaque progression correlation results from TW models were consistent with that from the FSI models(positive/negative correlation agreement rate 87.5%).In terms of time cost,TW models shortened the 10-15 days of FSI model construction and solution time per patient to several hours under the premise of ensuring the precision,which would make it possible to implement biomechanical models for realistic clinic applications.Large scale studies are needed to further investigate the feasibility of using TW models as approximation for FSI models.更多还原