Objectives

GABA is the most important inhibitory neurotransmitter. Thus, variation in its concentration is connected to a wide variety of diseases. However, the low concentration and the overlap of more prominent resonances hamper GABA quantification using MR spectroscopy. The hippocampus plays a pivotal role in neurodegeneration. Susceptibility discontinuities in the vicinity of the hippocampus cause strong B₀ inhomogeneities, impeding GABA spectroscopy. The aim of this work is to improve the reproducibility of hippocampal GABA+ MRS.

Methods

The GABA+/total creatine ratio in the hippocampus was measured using a MEGA-sLASER sequence at 7 Tesla. 10 young healthy volunteers participated in the study. A dedicated pre-processing approach was established. Spectral quantification was performed with Tarquin. The quantification parameters were carefully adjusted to ensure optimal quantification.

Results

An inter-subject coefficient of variation of the GABA+/total creatine of below 15% was achieved. Additional to spectral registration, which is essential to obtain reproducible GABA measures, eddy current compensation and additional difference artifact suppression improved the reproducibility. The mean FWHM was 23.1 Hz (0.078 ppm).

Conclusion

The increased spectral dispersion of ultra-high-field spectroscopy allows for reproducible spectral quantification, despite a very broad line width. The achieved reproducibility enables the routine use of hippocampal GABA spectroscopy at 7 Tesla.

中文翻译：

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关于使用优化分析管道在 7T 下海马 MEGA-sLASER GABA MRS 的重现性。

目标

GABA是最重要的抑制性神经递质。因此，其浓度的变化与多种疾病有关。然而，低浓度和更显着共振的重叠阻碍了使用 MR 光谱的 GABA 量化。海马在神经退行性变中起关键作用。海马附近的易感性不连续性导致强烈的B ₀不均匀性，阻碍 GABA 光谱。这项工作的目的是提高海马 GABA+ MRS 的重现性。

方法

使用 MEGA-sLASER 序列在 7 特斯拉测量海马中的 GABA+/总肌酸比率。10名年轻的健康志愿者参加了这项研究。建立了专门的预处理方法。用 Tarquin 进行光谱定量。仔细调整量化参数以确保最佳量化。

结果

GABA+/总肌酸的个体间变异系数低于 15%。除了光谱配准，这对于获得可重复的 GABA 测量是必不可少的，涡流补偿和额外的差异伪影抑制提高了可重复性。平均 FWHM 为 23.1 Hz (0.078 ppm)。

结论

尽管线宽非常宽，但超高场光谱增加的光谱色散允许可重复的光谱量化。所达到的可重复性使海马 GABA 光谱能够在 7 特斯拉下常规使用。