Frayne R, Steinman D A, Ethier C R, Rutt B K
Department of Radiology, University of Western Ontario, London, Canada.
J Magn Reson Imaging. 1995 Jul-Aug;5(4):428-31. doi: 10.1002/jmri.1880050410.
The accuracy of MR phase contrast (PC) velocity measurements for unsteady flow has been quantitatively assessed. Spatially resolved velocity fields were measured in a long straight tube using a gated PC technique, and the resulting MR PC velocity data were compared with velocities derived from the analytic Womersley solution to the Navier-Stokes equations governing fluid flow. The overall root-mean-square (rms) difference between the measured and analytic velocities was 1.6 cm s-1 for nominally sinusoidal flow waveforms with peak velocities ranging from 51.6 cm s-1 to 59.8 cm s-1. This rms difference corresponded to 7.5% of the mean fluid velocity, which is similar to the cited accuracy of approximately 5% for MR PC velocimetry for steady flows. Linear regression between the PC velocity measurements and the velocities obtained using the analytic expression was highly significant (r2 = 0.997) and yielded a slope of 0.998, close to the expected value of 1. We conclude that the gated MR PC velocity measurements in unsteady flow are accurate.
已对用于非定常流动的磁共振相位对比（PC）速度测量的准确性进行了定量评估。使用门控PC技术在长直管中测量空间分辨的速度场，并将所得的磁共振PC速度数据与从描述流体流动的纳维 - 斯托克斯方程的解析沃默斯利解得出的速度进行比较。对于峰值速度范围为51.6 cm s⁻¹至59.8 cm s⁻¹的名义正弦流动波形，测量速度与解析速度之间的总体均方根（rms）差为1.6 cm s⁻¹。该均方根差相当于平均流体速度的7.5%，这与文献中报道的稳态流动磁共振PC测速法约5%的精度相似。PC速度测量值与使用解析表达式获得的速度之间的线性回归非常显著（r² = 0.997），斜率为0.998，接近预期值1。我们得出结论，非定常流动中的门控磁共振PC速度测量是准确的。
