A REDUCED POWER SELECTIVE ADIABATIC SPIN-ECHO PULSE SEQUENCE
A REDUCED POWER SELECTIVE ADIABATIC SPIN-ECHO PULSE SEQUENCE
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DOI：
10.1002/mrm.1910180105
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发表时间：
1991-03-01
影响因子：
3.3
通讯作者：
MACOVSKI, A
中科院分区：
文献类型：
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作者：
CONOLLY, S;GLOVER, G;MACOVSKI, A
我们介绍了一种适用于产生选择性自旋回波的选择性绝热脉冲序列，用于磁共振成像和光谱学。这项技术很简单；可以使用任何一对相同的选择性绝热反转脉冲产生的回声。横跨切片的非线性相位被第二个π脉冲完美地补偿。这种补偿不受射频不均匀和非线性的影响。对于成像应用，我们专注于脉冲序列的降低功率版本，其中在存在随时间变化的梯度的情况下，时间可变地被换取为RF幅度。这种技术被称为可变速率激励，当应用于幅度调制脉冲时，会轻微地降低非共振切片轮廓。我们给出了理论解释和实验结果，表明可变速率绝热脉冲不受磁共振成像中通常遇到的幅度的非共振退化的影响。©1991学术出版社。Inc.
We introduce a selective adiabatic pulse sequence suitable for generating selective spin‐echoes for both MR imaging and spectroscopy. The technique is simple; one uses the echo generated by any pair of identical selective adiabatic inversion pulses. The nonlinear phase across the slice is compensated perfectly by the second π pulse. This compensation is immune to RF inhomogeneity and nonlinearity. For imaging applications, we concentrate on a reduced‐power version of the pulse sequence in which time is traded off variably for RF amplitude in the presence of a time‐varying gradient. This technique, known as variable‐rate excitation, mildly degrades the off‐resonant slice profile when applied to amplitude‐modulated pulses. We present theoretical explanations and experimental results that show that the variable‐rate adiabatic pulses are immune to off‐resonant degradation of the magnitude normally encountered in MR imaging. © 1991 Academic Press. Inc.