Davis W L, Turski P A, Gorbatenko K G, Weber D
Department of Radiology, University of Utah Medical Center, Salt Lake City 84132.
J Magn Reson Imaging. 1993 Jul-Aug;3(4):603-9. doi: 10.1002/jmri.1880030409.
The velocity-phase relationship intrinsic to phase-contrast magnetic resonance (MR) angiography permits the quantitative and qualitative assessment of blood flow. The ability to measure velocity and vessel cross-sectional area allows noninvasive assessment of volume flow rate (VFR) in the internal carotid artery (ICA). Phase-contrast techniques also demonstrate flow direction. Using two-dimensional cine phase-contrast angiography, the authors evaluated VFR in the ICA and collateral flow about the circle of Willis in 15 patients with ischemic neurologic symptoms. The VFR in each carotid artery was correlated with the degree of stenosis and presence or absence of abnormal circle of Willis collateral flow. There was a correlation between a decrease in VFR and abnormal circle of Willis collateral flow. In addition, a correlation between severe stenosis and a decrease in VFR was found. In patients with ischemic neurologic symptoms without severe stenosis (< 70% diameter stenosis), no decrease in VFR was seen. It is hoped that flow quantification and directional flow imaging with phase-contrast angiography will help further characterize carotid artery occlusive disease by enabling assessment of VFR changes associated with ischemic neurologic symptoms. This study also supports the hypothesis that two mechanisms--hemodynamic and embolic--play a role in ischemic neurologic symptoms.
相位对比磁共振血管造影固有的速度-相位关系能够对血流进行定量和定性评估。测量速度和血管横截面积的能力使得无创评估颈内动脉（ICA）的容积流率（VFR）成为可能。相位对比技术还能显示血流方向。作者采用二维电影相位对比血管造影术，对15例有缺血性神经症状的患者的颈内动脉VFR以及 Willis 环周围的侧支血流进行了评估。每条颈动脉的VFR与狭窄程度以及 Willis 环侧支血流是否异常相关。VFR降低与 Willis 环侧支血流异常之间存在相关性。此外，还发现严重狭窄与VFR降低之间存在相关性。在无严重狭窄（直径狭窄<70%）的缺血性神经症状患者中，未观察到VFR降低。希望通过相位对比血管造影进行血流定量和血流方向成像，能够通过评估与缺血性神经症状相关的VFR变化，进一步明确颈动脉闭塞性疾病的特征。本研究还支持血流动力学和栓塞这两种机制在缺血性神经症状中起作用的假说。
