Wedeen V J, Rosen B R, Buxton R, Brady T J
Magn Reson Med. 1986 Apr;3(2):226-41. doi: 10.1002/mrm.1910030206.
Projective MR images of vascular anatomy and flow are performed at 0.14 T by using phase contrast to suppress the signal contribution of the stationary background. The source of the contrast is the distinctive phase evolution of moving protons under the influence of the read-out gradient of a conventional two-dimensional Fourier transform (2D FT) spin-echo pulse sequence. By using short echo times, small phase shifts may be obtained. When phase shifts are less than about 45 degrees, the phase contrast assumes a simple and useful form. The flow image intensity at any pixel becomes proportional to the net flux or flow volume of protons which cross the corresponding voxel. This proportionality is demonstrated in images of flow phantoms as is the reproducibility of measured flow volume under a variety of transformations of imaging conditions and of the subject. Projective images gated in vivo produce angiographic views of arteries and veins, in systole and diastole, in the neck of a dog and in the lower extremities of a human subject.
通过使用相位对比法抑制静止背景的信号贡献，在0.14T磁场下获取血管解剖结构和血流的投影磁共振图像。对比度的来源是在传统二维傅里叶变换（2D FT）自旋回波脉冲序列读出梯度影响下，移动质子独特的相位演变。通过使用短回波时间，可以获得小的相移。当相移小于约45度时，相位对比呈现出一种简单且有用的形式。任何像素处的血流图像强度与穿过相应体素的质子净通量或血流量成正比。这种比例关系在血流模型图像中得到了证明，在各种成像条件和受试者的变换下，测量血流量的可重复性也是如此。体内门控的投影图像可生成狗颈部和人类受试者下肢在收缩期和舒张期动脉和静脉的血管造影视图。
