Global Applied Science Laboratory, GE Healthcare, Palaiseau, France.
J Magn Reson. 2011 Aug;211(2):121-33. doi: 10.1016/j.jmr.2011.05.005. Epub 2011 May 15.
The nCPMG sequence is based on a particular phase modulation of the refocusing pulse train, and was originally designed for rendering the spin echo amplitude insensitive to the initial magnetization phase. This pulse sequence has the peculiarity of being easily invertible, which enables perfect driven equilibrium experiments, in the absence of relaxation. This magnetization 'realignment' is effective for all three components. Hence the overall operation is transparent. Supporting theory is presented here, together with the first direct experimental proof of the claim. The experiment shows that, with the present stabilization sequence, perfect realignment is indeed made possible for a range of refocusing pulse nutation angles from 130° to 230°.
nCPMG 序列基于聚焦脉冲序列的特定相位调制,最初设计用于使自旋回波幅度对初始磁化相位不敏感。该脉冲序列具有易于反转的特点,可在无弛豫的情况下实现完美的驱动平衡实验。这种磁化“重定向”对所有三个分量都有效。因此,整体操作是透明的。本文提出了相关理论,并提供了第一个直接实验证据来证明该断言。实验表明,使用目前的稳定化序列,对于聚焦脉冲扭转角从 130°到 230°的一系列范围,确实可以实现完美的重定向。