Oeltzschner Georg, Schnitzler Alfons, Wickrath Frithjof, Zöllner Helge Jörn, Wittsack Hans-Jörg
Institute of Clinical Neuroscience and Medical Psychology, Medical Faculty, Heinrich-Heine-University Düsseldorf, D-40225, Düsseldorf, Germany; Department of Diagnostic and Interventional Radiology, University Dusseldorf, Medical Faculty, D-40225, Düsseldorf, Germany; Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, United States; F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States.
Institute of Clinical Neuroscience and Medical Psychology, Medical Faculty, Heinrich-Heine-University Düsseldorf, D-40225, Düsseldorf, Germany.
Magn Reson Imaging. 2016 Oct;34(8):1057-63. doi: 10.1016/j.mri.2016.04.013. Epub 2016 Apr 21.
To compare two different methods of obtaining the water reference for determination of quantitative water-scaled in vivo concentration estimates of γ-aminobutyric acid (GABA).
Water-scaled GABA estimates from localized J-difference edited MR spectroscopy experiments can be computed using standard values for tissue-specific water content and relaxation times. Water content and relaxation may, however, be altered in pathology. This work re-analyzed data from a recent study in healthy controls and patients with minimal (mHE) or grade I (HE 1) hepatic encephalopathy, a disease associated with slight elevation of brain water content. J-difference edited MR spectroscopy data were combined with quantitative brain water measures, which provided individual water density references and T1 relaxation times. Resulting GABA estimates were compared to concentration values obtained using standard tissue-specific water content and relaxation values.
Occipital GABA concentration values obtained from individual water and T1 maps were 1.64±0.35mM in controls, and significantly higher (P<0.01) than in mHE (1.15±0.28mM) and HE 1 patients (1.18±0.09mM). Results from the tissue-dependent approach (1.58±0.30mM (controls), 1.10±0.27mM (mHE) and 1.12±0.12mM (HE 1)) were slightly lower (P<0.05 in each group).
Water-scaled in vivo GABA estimates can be obtained with individual water density and T1 relaxation mapping. This approach may be useful for studying GABA levels in pathologies with substantial brain water content or relaxation changes.
比较两种不同的获取水参考值的方法，用于测定γ-氨基丁酸（GABA）体内定量水标度浓度估计值。
通过局部J-差异编辑磁共振波谱实验得到的水标度GABA估计值，可以使用组织特异性含水量和弛豫时间的标准值来计算。然而，含水量和弛豫在病理状态下可能会发生改变。这项工作重新分析了最近一项针对健康对照者以及患有轻度（mHE）或I级（HE 1）肝性脑病患者的研究数据，肝性脑病是一种与脑含水量轻微升高相关的疾病。J-差异编辑磁共振波谱数据与定量脑水测量相结合，后者提供了个体水密度参考值和T1弛豫时间。将得到的GABA估计值与使用标准组织特异性含水量和弛豫值获得的浓度值进行比较。
从个体水和T1图谱获得的枕叶GABA浓度值在对照组中为1.64±0.35mM，显著高于mHE组（1.15±0.28mM）和HE 1患者组（1.18±0.09mM）（P<0.01）。基于组织依赖方法的结果（对照组为1.58±0.30mM，mHE组为1.10±0.27mM，HE 1组为1.12±0.12mM）略低（每组P<0.05）。
通过个体水密度和T1弛豫图谱可以获得体内水标度GABA估计值。这种方法可能有助于研究脑含水量或弛豫发生显著变化的病理状态下的GABA水平。
