Polzin J A, Alley M T, Korosec F R, Grist T M, Wang Y, Mistretta C A
Department of Radiology, University of Wisconsin, Madison, USA.
J Magn Reson Imaging. 1995 Mar-Apr;5(2):129-37. doi: 10.1002/jmri.1880050202.
Magnetic resonance (MR) phase-difference methods work well for measuring volumetric flow rates when the vessel diameter is large compared with the in-plane voxel dimensions. For small vessels (eg, coronary arteries), partial-volume effects introduce substantial errors in the measured volume flow rate. To correctly measure flow rates through a voxel, both the fraction of the voxel containing moving spins and the phase shift imparted to those spins must be known. The authors propose a flow measurement method that combines information obtained with both the complex-difference and phase-difference processing techniques and thereby provides the fractional volume occupied by the moving spins and the phase of those spins. The complex-difference flow map method proposed results in improved accuracy of MR phase-contrast flow measurements in the presence of partial-volume effects.
当血管直径相对于平面内体素尺寸较大时，磁共振（MR）相位差方法在测量体积流速方面效果良好。对于小血管（如冠状动脉），部分容积效应会在测量的体积流速中引入大量误差。为了正确测量通过体素的流速，必须知道体素中包含移动自旋的部分以及赋予这些自旋的相移。作者提出了一种流量测量方法，该方法结合了通过复差分和相位差处理技术获得的信息，从而提供了移动自旋所占的分数体积以及这些自旋的相位。所提出的复差分流图方法在存在部分容积效应的情况下提高了MR相位对比血流测量的准确性。
