Zhang Qi, Steinman David A, Friedman Morton H
Department of Electronic and Information Engineering, Shanghai University, Shanghai, China.
J Biomech Eng. 2010 Nov;132(11):114505. doi: 10.1115/1.4002538.
The detailed geometry of atherosclerosis-prone vascular segments may influence their susceptibility by mediating local hemodynamics. An appreciation of the role of specific geometric variables is complicated by the considerable correlation among the many parameters that can be used to describe arterial shape and size. Factor analysis is a useful tool for identifying the essential features of such an inter-related data set, as well as for predicting hemodynamic risk in terms of these features and for interpreting the role of specific geometric variables. Here, factor analysis is applied to a set of 14 geometric variables obtained from magnetic resonance images of 50 human carotid bifurcations. Two factors alone were capable of predicting 12 hemodynamic metrics related to shear and near-wall residence time with adjusted squared Pearson's correlation coefficient as high as 0.54 and P-values less than 0.0001. One factor measures cross-sectional expansion at the bifurcation; the other measures the colinearity of the common and internal carotid artery axes at the bifurcation. The factors explain the apparent lack of an effect of branch angle on hemodynamic risk. The relative risk among the 50 bifurcations, based on time-average wall shear stress, could be predicted with a sensitivity and specificity as high as 0.84. The predictability of the hemodynamic metrics and relative risk is only modestly sensitive to assumptions about flow rates and flow partitions in the bifurcation.
易发生动脉粥样硬化的血管段的详细几何结构可能通过介导局部血流动力学来影响其易感性。由于可用于描述动脉形状和大小的众多参数之间存在相当大的相关性，因此对特定几何变量作用的认识变得复杂。因子分析是一种有用的工具，可用于识别此类相互关联数据集的基本特征，以及根据这些特征预测血流动力学风险并解释特定几何变量的作用。在此，因子分析应用于从50个人类颈动脉分叉的磁共振图像中获得的一组14个几何变量。仅两个因子就能够预测与剪切力和近壁停留时间相关的12个血流动力学指标，调整后的皮尔逊相关系数平方高达0.54，P值小于0.0001。一个因子测量分叉处的横截面扩张；另一个因子测量分叉处颈总动脉和颈内动脉轴的共线性。这些因子解释了分支角度对血流动力学风险明显缺乏影响的原因。基于时间平均壁面剪应力，50个分叉之间的相对风险可以以高达0.84的敏感性和特异性进行预测。血流动力学指标和相对风险的可预测性对分叉处流速和血流分配假设的敏感性仅为中等。
