Quantitative phase-velocity MR imaging of in-plane laminar flow: effect of fluid velocity, vessel diameter, and slice thickness.
Quantitative phase-velocity MR imaging of in-plane laminar flow: effect of fluid velocity, vessel diameter, and slice thickness.
复制标题
面内层流的定量相速度 MR 成像：流体速度、血管直径和切片厚度的影响。
DOI：
10.1118/1.596854
复制
发表时间：
1992
期刊：
影响因子：
3.8
通讯作者：
Fatouros,PP
中科院分区：
文献类型：
--
作者：
Kraft,KA;Fei,DY;Fatouros,PP
定量MR相位成像经常用于测量自旋速度。然而，当获取携带层流的血管的平面内相位图像时，可能会出现潜在的困难，其中流体速度分布是抛物线。在这种情况下，取决于流速（v）、血管直径（D）和所选择的MR切片厚度（ST），在每个管腔内体素内将在一定程度上存在自旋速度梯度。可以预期所得到的体素内相位分散影响净像素相位值，并且因此损害相移和速度之间的假定线性相关性。在这项研究中，改变ofv，D和ST上的表观图像相位的影响进行了研究的情况下，层流方向平行于序列读取梯度。一个理论模型的开发和实验测试的结论使用流量幻影。数据表明，当定量平面内相流图像时，当净流动诱导相移较小且MR切片厚度是血管直径的一个可观部分时，可能会发生显著的速度低估。
Quantitative MR phase imaging is frequently used to measure spin velocities. A potential difficulty may arise, however, when in‐plane phase images are acquired of a vessel carrying laminar flow, for which the fluid velocity profile is parabolic. In that case, depending on the flow velocity (v), the vessel diameter (D), and the chosen MR slice thickness (ST), a spin velocity gradient will be present to some extent within each intraluminal voxel. The resulting intravoxel phase dispersion may be expected to affect the net pixel phase value, and hence compromise the assumed linear correlation between phase shift and velocity. In this study, the effects of alterations ofv,D, and ST on the apparent image phase are investigated for the case of laminar flow directed parallel to the sequence read gradient. A theoretical model is developed and the conclusions experimentally tested using a flow phantom. The data demonstrate that when quantitating in‐plane phase‐flow images, significant velocity underestimations may occur when the net flow‐induced phase shifts are small and the MR slice thickness is an appreciable fraction of the vessel diameter.