Kwiat D, Einav S, Elad D
Biomedical Engineering Program, Faculty of Engineering, Tel Aviv University, Israel.
Med Phys. 1990 Mar-Apr;17(2):258-63. doi: 10.1118/1.596504.
A new magnetic resonance imaging of flow by a method of successive excitation of a moving slice is presented here. The method, which in general belongs to the class of time-of-flight methods, is based upon selectively changing the frequencies in a sequence of rf pulses in such a way that a selected slice moves through the imaged volume in a preselected direction and velocity, and is repeatedly excited. It is claimed that most of the measured signal is contributed by only those parts of the imaged substance that move with the selected slice. The activation procedure of the flowing spins, which is presented here, enhances the imaging of the flowing matter and reduces the signal from static matter. A specially tailored selective sequence of a rf alpha-pulses has been developed. During this sequence, a set of rephasing 180 degrees selective rf pulses is applied. At the end of this sequence an additional 180 degrees rf pulse is applied to eliminate redundant signals from the static matter in the last activated slice.
本文介绍了一种通过移动切片连续激发法进行血流磁共振成像的新方法。该方法总体上属于飞行时间法，其原理是在射频脉冲序列中选择性地改变频率，使选定的切片以预选的方向和速度穿过成像体积，并被重复激发。据称，大部分测量信号仅由成像物质中与选定切片一起移动的那些部分贡献。本文提出的流动自旋激活程序增强了流动物质的成像，并减少了来自静态物质的信号。已开发出一种专门定制的射频α脉冲选择性序列。在这个序列中，应用了一组180度的重相位选择性射频脉冲。在该序列结束时，再施加一个180度的射频脉冲，以消除最后激活切片中静态物质的冗余信号。
