体内 J 重聚焦氢磁共振波谱。
In vivo H MR spectroscopy with J-refocusing.
机构信息
Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, Minnesota, USA.
Department of Chemistry, University of Miami, Coral Gables, Florida, USA.
出版信息
Magn Reson Med. 2021 Dec;86(6):2957-2965. doi: 10.1002/mrm.28936. Epub 2021 Jul 26.
PURPOSE
The goal of this study was to propose a novel localized proton MR spectroscopy (MRS) sequence that reduces signal loss due to J-modulation in the rat brain in vivo.
METHODS
Sprague-Dawley rats were studied at 9.4 T. A semi-LASER sequence with evenly distributed echo-time (T ) was used, and a 90° J-refocusing pulse was inserted at T /2. Proton spectra were acquired at two T s (30 and 68 ms), with and without the J-refocused pulse. Data were processed in MATLAB and quantified with LCModel.
RESULTS
The J-refocused spectrum acquired at T = 30 ms did not show any signal losses due to J-modulation and had comparable spectral pattern to the one acquired with semi-LASER using the minimum achievable T . Higher signal amplitudes for glutamine, γ-aminobutyric acid and glutathione led to more reliable quantification precision for these metabolites. The refocused signal intensities at T = 68 ms were also unaffected by J-modulation but were smaller than the signals at T = 30 ms mainly due to transverse T relaxation of metabolites.
CONCLUSION
The proposed localized MRS sequence will be beneficial in both animal and human MRS studies when using ultra-short T is not possible while also providing more reliable quantification precision for J-coupled metabolites.
目的
本研究旨在提出一种新的局部质子磁共振波谱（MRS）序列，以减少活体大鼠脑内 J 调制引起的信号损失。
方法
在 9.4T 下对 Sprague-Dawley 大鼠进行研究。使用具有均匀分布回波时间（T）的半 LASER 序列，并在 T/2 处插入 90°J 重聚焦脉冲。在两个 T（30 和 68ms）处采集质子谱，有和没有 J 重聚焦脉冲。数据在 MATLAB 中进行处理，并使用 LCModel 进行定量。
结果
在 T=30ms 处采集的 J 重聚焦谱没有由于 J 调制引起的任何信号损失，并且与使用最小可实现 T 的半 LASER 采集的谱具有相似的谱图模式。谷氨酸、γ-氨基丁酸和谷胱甘肽的信号幅度更高，导致这些代谢物的定量精度更可靠。在 T=68ms 处的重聚焦信号强度也不受 J 调制的影响，但由于代谢物的横向 T2 弛豫，信号强度小于 T=30ms 处的信号强度。
结论
当无法使用超短 T 时，该提议的局部 MRS 序列将有益于动物和人类 MRS 研究，同时为 J 偶联代谢物提供更可靠的定量精度。
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