Rosenfeld D, Zur Y
School of Physics and Astronomy, Tel-Aviv University, Israel.
Magn Reson Med. 1996 Jul;36(1):124-36. doi: 10.1002/mrm.1910360121.
Adiabatic pulses play an important role in magnetization inversion in the presence of RF field inhomogeneity. In this work the authors present an efficient adiabatic inversion pulse that is able to selectively invert magnetization over a large frequency bandwidth in a short time. The pulse is constructed in two steps: (i) the optimal trajectory is determined and (ii) the optimal rate of motion along that trajectory is determined. The resulting pulse enables separately controlling and trading off the pulse duration against the transition width. The superiority of this pulse over the well known sech/tanh adiabatic pulse is demonstrated in a scenario where a large bandwidth should be inverted at a short time using limited B1 amplitude.
绝热脉冲在存在射频场不均匀性的情况下的磁化反转中起着重要作用。在这项工作中，作者提出了一种高效的绝热反转脉冲，它能够在短时间内在大频率带宽上选择性地反转磁化。该脉冲分两步构建：（i）确定最优轨迹，（ii）确定沿该轨迹的最优运动速率。所得脉冲能够分别控制脉冲持续时间与跃迁宽度，并进行权衡。在使用有限B1幅度在短时间内反转大带宽的情况下，证明了该脉冲优于著名的sech/tanh绝热脉冲。
