Division of Cardiovascular Medicine, Department of Medical and Health Sciences, Linköping University, Linköping, Sweden.
Center for Medical Image Science and Visualization (CMIV), Linköping University, Linköping, Sweden.
Sci Rep. 2016 Dec 22;6:39773. doi: 10.1038/srep39773.
Flow-induced blood damage plays an important role in determining the hemodynamic impact of abnormal blood flow, but quantifying of these effects, which are dominated by shear stresses in highly fluctuating turbulent flow, has not been feasible. This study evaluated the novel application of turbulence tensor measurements using simulated 4D Flow MRI data with six-directional velocity encoding for assessing hemodynamic stresses and corresponding blood damage index (BDI) in stenotic turbulent blood flow. The results showed that 4D Flow MRI underestimates the maximum principal shear stress of laminar viscous stress (PLVS), and overestimates the maximum principal shear stress of Reynolds stress (PRSS) with increasing voxel size. PLVS and PRSS were also overestimated by about 1.2 and 4.6 times at medium signal to noise ratio (SNR) = 20. In contrast, the square sum of the turbulent viscous shear stress (TVSS), which is used for blood damage index (BDI) estimation, was not severely affected by SNR and voxel size. The square sum of TVSS and the BDI at SNR >20 were underestimated by less than 1% and 10%, respectively. In conclusion, this study demonstrated the feasibility of 4D Flow MRI based quantification of TVSS and BDI which are closely linked to blood damage.
血流诱导性血液损伤在确定异常血流的血液动力学影响方面起着重要作用，但量化这些由高度波动的湍流剪切应力主导的影响还不可行。本研究通过使用具有六向速度编码的模拟 4D Flow MRI 数据评估了湍流张量测量的新应用，以评估狭窄湍流血流中的血液动力学应力和相应的血液损伤指数 (BDI)。结果表明，4D Flow MRI 会低估层流粘性应力的最大主剪切应力 (PLVS)，并随着体素尺寸的增加而高估雷诺应力的最大主剪切应力 (PRSS)。在中等信噪比 (SNR) = 20 时，PLVS 和 PRSS 也分别高估了约 1.2 倍和 4.6 倍。相比之下，用于血液损伤指数 (BDI) 估计的湍流粘性剪切应力的平方和 (TVSS) 受 SNR 和体素大小的影响不大。在 SNR >20 时，TVSS 的平方和以及 BDI 的值分别低估了不到 1%和 10%。总之，本研究证明了基于 4D Flow MRI 的 TVSS 和 BDI 定量的可行性，它们与血液损伤密切相关。
