Spectrally Selective B1-Insensitive T2 Magnetization Preparation Sequence
Spectrally Selective B1-Insensitive T2 Magnetization Preparation Sequence
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DOI：
10.1002/mrm.21742
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发表时间：
2009-06-01
影响因子：
3.3
通讯作者：
McVeigh, Elliot R.
中科院分区：
文献类型：
--
作者：
Nezafat, Reza;Ouwerkerk, Ronald;McVeigh, Elliot R.
提出了一种T-2磁化准备（T-2 Prep）序列，该序列对B-1场变化不敏感，同时提供脂肪抑制，而不会进一步增加比吸收率（SAR）。在较高磁场强度（B-0 >= 3 T）下增加的B-1不均匀性需要对B变化不太敏感的制备顺序。对于所提出的技术，在图像中的T-2加权是通过插入两个相等长的延迟，一个在初始反向绝热半通过（AHP）之后，另一个在BIR-4脉冲的最终AHP段之前，使用分段的B-1-不敏感旋转（BIR-4）绝热脉冲来实现的。该序列产生具有B-1和B-0不敏感性的T-2加权。为了同时抑制脂肪信号（以B-0不灵敏度为代价），延长第二延迟，使得脂肪由于其化学位移而积累额外的相位。数值模拟以及幻影和在体内的图像采集进行了显示所提出的技术的有效性。Magn Reson Med 61：1326-1335，2009. (C)2009 Wiley-Liss，Inc.
A T-2 magnetization-preparation (T-2 Prep) sequence is proposed that is insensitive to B-1 field variations and simultaneously provides fat suppression without any further increase in specific absorption rate (SAR). Increased B-1 inhomogeneity at higher magnetic field strength (B-0 >= 3T) necessitates a preparation sequence that is less sensitive to B, variations. For the proposed technique, T-2 weighting in the image is achieved using a segmented B-1-insensitive rotation (BIR-4) adiabatic pulse by inserting two equally long delays, one after the initial reverse adiabatic half passage (AHP), and the other before the final AHP segment of a BIR-4 pulse. This sequence yields T-2 weighting with both B-1 and B-0 insensitivity. To simultaneously suppress fat signal (at the cost of B-0 insensitivity), the second delay is prolonged so that fat accumulates additional phase due to its chemical shift. Numerical simulations as well as phantom and in vivo image acquisitions were performed to show the efficacy of the proposed technique. Magn Reson Med 61:1326-1335, 2009. (C) 2009 Wiley-Liss, Inc.