Echo time optimization for J-difference editing of glutathione at 3T.
Echo time optimization for J-difference editing of glutathione at 3T.
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DOI：
10.1002/mrm.26122
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发表时间：
2017-02
影响因子：
3.3
通讯作者：
Edden RA
中科院分区：
文献类型：
--
作者：
Chan KL;Puts NA;Snoussi K;Harris AD;Barker PB;Edden RA
研究谷胱甘肽j差编辑的回声时间依赖性，并确定3T时体内测量的最佳回声时间（TE）。通过空间分辨密度矩阵模拟和模拟实验，建立了3T时谷胱甘肽信号在编辑开、编辑关和差分光谱中的空间和TE调制。在5名健康受试者中获得体内数据，比较68 ms和120 ms的TE。在较长的TE下，高带宽、频率调制的选择性重聚焦脉冲也与传统的调幅脉冲进行了比较。模拟和弛豫校正幻像实验表明，最大编辑信号发生在TE 160 ms，忽略横向弛豫。考虑到体内T2弛豫时间为67-89 ms，估计体内最佳TE为120 ms。体内测量表明，这种TE比68 ms的TE多出15%的信号。通过使用改进的切片选择性重聚焦脉冲，进一步获得了57%的增益。使用TE 120 ms对谷胱甘肽进行j差编辑，由于提高了编辑效率，可以抵消T2损失，从而增加了信号。额外的回波时间还允许使用改进的切片选择性重聚焦脉冲，从而获得额外的信号增益。
To investigate the echo-time-dependence of J-difference editing of glutathione and to determine the optimal echo time (TE) for in vivo measurements at 3T. Spatially resolved density-matrix simulations and phantom experiments were performed at a range of TEs to establish the spatial and TE modulation of glutathione signals in editing-on, editing-off and difference spectra at 3T. In vivo data were acquired in five healthy subjects to compare TE 68 ms and TE 120 ms. At the longer TE, high-bandwidth, frequency-modulated slice-selective refocusing pulses was also compared with conventional amplitude-modulated pulses. Simulations and relaxation-corrected phantom experiments suggest that the maximum edited signal occurs at TE 160 ms, ignoring transverse relaxation. Considering in vivo T2 relaxation times of 67-89 ms, the optimal in vivo TE is estimated to be 120 ms. In vivo measurements showed that this TE gave 15% more signal than TE 68 ms. A further gain of 57% resulted from using improved slice-selective refocusing pulses. J-difference editing of glutathione using TE 120 ms delivers increased signal due to improved editing efficiency that more than offsets T2 losses. The additional echo time also allows for use of improved slice-selective refocusing pulses, which results in additional signal gains.