Wellnhofer Ernst, Goubergrits Leonid, Kertzscher Ulrich, Affeld Klaus
Biofluid Mechanics Laboratory, Charité-Universitätsmedizin Berlin, Berlin, Germany.
Biomed Eng Online. 2006 Jun 14;5:39. doi: 10.1186/1475-925X-5-39.
Clinical studies suggest that local wall shear stress (WSS) patterns modulate the site and the progression of atherosclerotic lesions. Computational fluid dynamics (CFD) methods based on in-vivo three-dimensional vessel reconstructions have recently been shown to provide prognostically relevant WSS data. This approach is, however, complex and time-consuming. Methodological simplifications are desirable in porting this approach from bench to bedside. The impact of such simplifications on the accuracy of geometry and wall shear stress calculations has to be investigated.
We investigated the influence of two methods of lumen reconstruction, assuming circular versus elliptical cross-sections and using different resolutions for the cross-section reconstructions along the vessel axis. Three right coronary arteries were used, of which one represented a normal coronary artery, one with "obstructive", and one with "dilated" coronary atherosclerosis. The vessel volume reconstruction was performed with three-dimensional (3D) data from a previously validated 3D angiographic reconstruction of vessel cross-sections and vessel axis.
The difference between the two vessel volumes calculated using the two evaluated methods is less than 1 %. The difference, of the calculated pressure loss, was between 2.5% and 8.5% for the evaluated methods. The distributions of the WSS histograms were nearly identical and strongly cross-correlated (0.91-0.95). The good agreement of the results was confirmed by a Chi-square test.
A simplified approach to the reconstruction of coronary vessel lumina, using circular cross-sections and a reduced axial resolution of about 0.8 mm along the vessel axis, yields sufficiently accurate calculations of WSS.
临床研究表明，局部壁面切应力（WSS）模式可调节动脉粥样硬化病变的部位和进展。基于体内三维血管重建的计算流体动力学（CFD）方法最近已被证明可提供具有预后相关性的WSS数据。然而，这种方法复杂且耗时。将这种方法从实验室应用到临床需要进行方法简化。必须研究这种简化对几何形状和壁面切应力计算准确性的影响。
我们研究了两种管腔重建方法的影响，一种假设横截面为圆形，另一种假设为椭圆形，并沿血管轴使用不同的分辨率进行横截面重建。使用了三支右冠状动脉，其中一支代表正常冠状动脉，一支有“阻塞性”病变，另一支有“扩张性”冠状动脉粥样硬化病变。血管体积重建是利用先前验证过的血管横截面和血管轴的三维血管造影重建的三维数据进行的。
使用两种评估方法计算得到的两个血管体积之间的差异小于1%。评估方法计算得到的压力损失差异在2.5%至8.5%之间。WSS直方图的分布几乎相同且具有很强的互相关性（0.91 - 0.95）。通过卡方检验证实了结果的良好一致性。
采用圆形横截面并沿血管轴将轴向分辨率降低至约0.8 mm的简化冠状动脉管腔重建方法，能够得到足够准确的WSS计算结果。
