Ziegler Magnus, Alfraeus Jesper, Good Elin, Engvall Jan, de Muinck Ebo, Dyverfeldt Petter
Division of Cardiovascular Medicine, Department of Health, Medicine and Caring Sciences, Linköping University, Linköping, Sweden.
Center for Medical Image Science and Visualization (CMIV), Linköping University, Linköping, Sweden.
Front Cardiovasc Med. 2021 Feb 3;7:617755. doi: 10.3389/fcvm.2020.617755. eCollection 2020.
Atherosclerosis manifests as a focal disease, often affecting areas with complex hemodynamics such as the carotid bifurcation. The magnitude and regularity of the hemodynamic shear stresses acting on the vessel wall are thought to generate risk patterns unique to each patient and play a role in the pathogenesis of atherosclerosis. The involvement of different expressions of shear stress in the pathogenesis of carotid atherosclerosis highlights the need to characterize and compare the differential impact of the various expressions of shear stress in the atherosclerotic carotid bifurcation. Therefore, the aim of this study is to characterize and compare hemodynamic wall shear stresses (WSS) in the carotid arteries of subjects with asymptomatic atherosclerotic plaques. Shear stresses were also compared against vessel diameter and bifurcation angle to examine the relationships with the geometry of the carotid bifurcation. 4D Flow MRI and contrast-enhanced MRA data were acquired for 245 subjects with atherosclerotic plaques of at least 2.7 mm in conjunction with the Swedish CArdioPulmonary bioImage Study (SCAPIS). Following automatic segmentation and geometric analysis, time-resolved WSS and near-wall turbulent kinetic energy (nwTKE) were derived from the 4D Flow data. Whole-cycle parameters including time-averaged WSS and nwTKE, and the oscillatory shear index (OSI) were calculated. Pairwise Spearman rank-correlation analyses were used to investigate relationships among the hemodynamic as well as geometric parameters. One hundred and seventy nine subjects were successfully segmented using automated tools and subsequently geometric and hemodynamic analyses were performed. Temporally resolved WSS and nwTKE were strongly correlated, ρ = 0.64. Cycle-averaged WSS and nwTKE were moderately correlated, ρ = 0.57. Cycle-average nwTKE was weakly correlated to OSI (ρ = -0.273), revealing that nwTKE provides information about disturbed flow on the vessel wall that OSI does not. In this cohort, there was large inter-individual variation for both WSS and nwTKE. Both WSS and nwTKE varied most within the external carotid artery. WSS, nwTKE, and OSI were weakly correlated to vessel diameter and bifurcation angle. The turbulent and mean component of WSS were examined together for the first time, and a strong correlation was found between them. nwTKE presents the opportunity to quantify turbulent wall stresses and gain insight into the effects of disturbed flow on the vessel wall. Neither vessel diameter nor bifurcation angle were found to be strongly correlated to the turbulent or mean component of WSS in this cohort.
动脉粥样硬化表现为一种局灶性疾病，常累及具有复杂血流动力学的区域，如颈动脉分叉处。作用于血管壁的血流动力学剪切应力的大小和规律性被认为会产生每个患者独特的风险模式，并在动脉粥样硬化的发病机制中起作用。剪切应力的不同表现形式在颈动脉粥样硬化发病机制中的参与凸显了表征和比较剪切应力各种表现形式在动脉粥样硬化性颈动脉分叉处的差异影响的必要性。因此，本研究的目的是表征和比较无症状动脉粥样硬化斑块受试者颈动脉中的血流动力学壁面剪切应力（WSS）。还将剪切应力与血管直径和分叉角度进行比较，以研究与颈动脉分叉几何形状的关系。结合瑞典心肺生物图像研究（SCAPIS），对245名动脉粥样硬化斑块至少为2.7mm的受试者采集了4D流MRI和对比增强MRA数据。经过自动分割和几何分析后，从4D流数据中得出时间分辨的WSS和近壁湍动能（nwTKE）。计算了包括时间平均WSS、nwTKE和振荡剪切指数（OSI）在内的全周期参数。采用成对Spearman等级相关分析来研究血流动力学参数和几何参数之间的关系。使用自动化工具成功分割了179名受试者，随后进行了几何和血流动力学分析。时间分辨的WSS和nwTKE高度相关，ρ = 0.64。周期平均WSS和nwTKE中度相关，ρ = 0.57。周期平均nwTKE与OSI弱相关（ρ = -0.273），这表明nwTKE提供了关于血管壁上紊乱血流的信息，而OSI则没有。在这个队列中，WSS和nwTKE都存在很大的个体间差异。WSS和nwTKE在外颈动脉内变化最大。WSS、nwTKE和OSI与血管直径和分叉角度弱相关。首次同时检查了WSS的湍流分量和平均分量，发现它们之间存在很强的相关性。nwTKE提供了量化湍流壁面应力并深入了解紊乱血流对血管壁影响的机会。在这个队列中，未发现血管直径和分叉角度与WSS的湍流分量或平均分量有强相关性。
