脉冲系列脉冲系列是MRI中的重要问题,它与成象方法(如二维投影重建等)不同,是指RF脉冲激励的时序与性质,从而产生横向磁化的问题。为了解释各组织之间的相对对比度,需要较深入地理解RF脉冲序列对核自旋系统动力学的影响。NMR信号的幅度可由时变宏观磁化量M来描述: Pulse series Pulse series is an important issue in MRI. Unlike imaging methods (such as two-dimensional projection reconstruction, etc.), it refers to the timing and nature of RF pulse excitation, resulting in the problem of transverse magnetization. In order to explain the relative contrast between tissues, it is necessary to understand more deeply the influence of RF pulse sequences on the kinetics of nuclear spin systems. The magnitude of the NMR signal can be described by the time-varying macroscopic magnetization M: