Jeays A D, Lawford P V, Gillott R, Spencer P, Barber D C, Bardhan K D, Hose D R
Medical Physics, University of Sheffield, Royal Hallamshire Hospital, Glossop Rd, Sheffield, S10 2JF, UK.
J Biomech. 2007;40(9):1916-26. doi: 10.1016/j.jbiomech.2006.09.009. Epub 2006 Oct 30.
In contrast to its prevalence in the surrounding vasculature, occurrence of primary atherosclerotic disease in the superior mesenteric artery (SMA) is rare (Glagov et al., 1988. Hemodynamics and atherosclerosis, Insights and perspectives gained from studies of human arteries. Archives of Pathology and Laboratory Medicine 112(10), 1018-1031; Hansen et al., 2004. Mesenteric artery disease in the elderly. Journal of Vascular Surgery 40(1), 45-52). We hypothesise that this sparing might be attributed to more favourable haemodynamic characteristics in the SMA than in other vessels locally. Dynamic magnetic resonance imaging (MRI) images established that the SMA is highly mobile (Jeays, 2006. Investigation of blood flow in the superior mesenteric artery and its potential influence on atheroma and gut ischaemia. Ph.D. Thesis, University of Sheffield), and thus that an analysis based on rigid geometry might be inappropriate. This paper describes an efficient methodology for the construction of a patient-specific, time-dependent model of an arterial segment and reports the results of a haemodynamic characterisation of the SMA for one individual. A transient computational fluid dynamic (CFD) model was constructed by morphing a parametric mesh constructed from simple geometric primitives. This process has the merit that it is easy to control the element size distribution mapped onto the original geometric primitives. It is robust in operation, and is ideally suited to the generation of dynamic CFD meshes of arterial systems that are free from major pathology. Flow boundary conditions were determined based on phase contrast MRI velocity measurements. Comparative studies with rigid walls and with moving walls, based on the transient data, indicated that, despite the significant motion of the SMA (radial dilation of the order of 10% and translation of the order of the radius), the maximum (spatially and temporally-resolved) wall shear stresses changed by no more than 21.6% of a global norm, and the average change was less than 2.1%.
与周围血管中动脉粥样硬化疾病的普遍存在形成对比的是，肠系膜上动脉（SMA）中原发性动脉粥样硬化疾病的发生较为罕见（Glagov等人，1988年。血流动力学与动脉粥样硬化，从人体动脉研究中获得的见解与观点。《病理学与检验医学档案》112(10)，1018 - 1031；Hansen等人，2004年。老年人肠系膜动脉疾病。《血管外科学杂志》40(1)，45 - 52）。我们推测这种差异可能归因于SMA比局部其他血管具有更有利的血流动力学特征。动态磁共振成像（MRI）图像显示SMA具有高度的可移动性（Jeays，2006年。肠系膜上动脉血流及其对动脉粥样硬化和肠道缺血潜在影响的研究。博士论文，谢菲尔德大学），因此基于刚性几何的分析可能并不合适。本文描述了一种构建特定患者的、随时间变化的动脉节段模型的有效方法，并报告了对一名个体的SMA进行血流动力学特征分析的结果。通过对由简单几何基元构建的参数化网格进行变形，构建了一个瞬态计算流体动力学（CFD）模型。这个过程的优点是易于控制映射到原始几何基元上的单元尺寸分布。它在操作上稳健，并且非常适合生成无重大病变的动脉系统动态CFD网格。基于相位对比MRI速度测量确定了流动边界条件。基于瞬态数据对刚性壁和移动壁的对比研究表明，尽管SMA有显著运动（径向扩张约10%，平移约为半径大小），但最大（空间和时间分辨）壁面剪应力的变化不超过全局标准的21.6%，平均变化小于2.1%。
