Efstathopoulos Efstathios P, Patatoukas Georgios, Pantos Ioannis, Benekos Odysseas, Katritsis Demosthenes, Kelekis Nikolaos L
2nd Department of Radiology, Medical School, University of Athens, Rimini 1, Chaidari, 12464 Athens, Greece.
Phys Med. 2008 Dec;24(4):175-81. doi: 10.1016/j.ejmp.2008.01.004. Epub 2008 Mar 4.
There is growing evidence that atherosclerosis, as well as endothelial biology, depend on arterial wall shear stress (WSS). Several methods of WSS calculation with varying degrees of complexity have been proposed. This study aimed at investigating whether the most straightforward and easier to apply of these methods give comparable results in clinical practice.
Complete velocity encoding measurements using phase contrast magnetic resonance imaging were performed in 20 patients at a level perpendicular to the long axis of the ascending aorta approximately 2cm above the aortic valve. WSS was calculated at this location on maximum systole. MR imaging was accomplished on a 1.5T scanner. Four methods were applied to calculate WSS; three of them are based on the predictions of Poiseuille's theory of flow, while the last one is based on calculations resulting by the application of the definition of WSS.
WSS calculated with the above mentioned methods was found to be in the range 4.2+/-1.8 to 3.5+/-1.7dynes/m(2). The velocity profile at the site of measurements can be described with a parabolic equation of the form u=ar(2)+br+c with an average r(2)=0.83, which is in good agreement with Poiseuille's theory of flow. Comparison of the results shows no statistically significant differences between WSS measurements calculated with these methods.
The four methods are equivalent in calculating WSS at the ascending aorta when blood flow velocities have a good parabolic distribution.
越来越多的证据表明，动脉粥样硬化以及内皮生物学都取决于动脉壁剪切应力（WSS）。已经提出了几种计算WSS的方法，其复杂程度各不相同。本研究旨在调查这些方法中最直接且易于应用的方法在临床实践中是否能给出可比的结果。
对20名患者在主动脉瓣上方约2cm处垂直于升主动脉长轴的水平进行使用相位对比磁共振成像的完整速度编码测量。在最大收缩期在该位置计算WSS。磁共振成像在1.5T扫描仪上完成。应用四种方法计算WSS；其中三种基于泊肃叶流动理论的预测，而最后一种基于应用WSS定义得出的计算结果。
用上述方法计算出的WSS在4.2±1.8至3.5±1.7达因/米²的范围内。测量部位的速度分布可用u = ar² + br + c形式的抛物线方程描述，平均r² = 0.83，这与泊肃叶流动理论高度一致。结果比较表明，用这些方法计算的WSS测量值之间无统计学显著差异。
当血流速度具有良好的抛物线分布时，这四种方法在计算升主动脉的WSS方面是等效的。
