通过体内单体素磁共振波谱法测量的脑谷氨酸浓度的区域和组织特异性差异。
Regional and tissue-specific differences in brain glutamate concentration measured by in vivo single voxel MRS.
作者信息
Zhang Yan, Shen Jun
机构信息
MR Spectroscopy Core Facility, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA.
MR Spectroscopy Core Facility, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA; Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA.
出版信息
J Neurosci Methods. 2015 Jan 15;239:94-9. doi: 10.1016/j.jneumeth.2014.09.021. Epub 2014 Sep 27.
BACKGROUND
There is growing interest in characterizing spatial distribution of glutamate (Glu) in brain disorders. Comparing the differences in Glu concentration using magnetic resonance spectroscopy (MRS) is hampered by the confounding effects of different anatomical regions and tissue composition.
NEW METHOD
Effect of tissue composition on Glu concentrations was studied by selecting closely adjacent voxels within a designated cortical region. Glu regional differences were assessed using voxels comprising essentially the same tissue composition from different cortical regions.
RESULTS
Using point-resolved-spectroscopy (PRESS)-based averaged echo time method, Glu concentration in the anterior cingulate cortex (ACC) was found to correlate strongly with tissue gray matter (GM) fraction (r=0.87, p=10(-5)). No significant regional difference in Glu concentration was found between frontal and occipital lobes (p=0.23) when the two measured voxels had essentially the same tissue composition.
COMPARISON WITH EXISTING METHODS
The method of the current study is aimed to circumvent the difficulties in differentiating anatomical region from tissue composition, given that both can lead to Glu variations in brain. Glu concentration versus tissue composition was measured in the same anatomical region, while the comparison of regional differences was performed with the two regions that had essentially the same tissue composition.
CONCLUSIONS
In brain cortices, Glu level is significantly higher in GM than in WM. Glu level difference between frontal lobe and occipital lobe is insignificant.
背景
人们对表征脑部疾病中谷氨酸（Glu）的空间分布越来越感兴趣。使用磁共振波谱（MRS）比较Glu浓度差异时，不同解剖区域和组织成分的混杂效应会造成干扰。
新方法
通过在指定皮质区域内选择紧密相邻的体素，研究组织成分对Glu浓度的影响。使用来自不同皮质区域、基本具有相同组织成分的体素评估Glu区域差异。
结果
使用基于点分辨波谱（PRESS）的平均回波时间方法，发现前扣带回皮质（ACC）中的Glu浓度与组织灰质（GM）分数密切相关（r = 0.87，p = 10⁻⁵）。当两个测量的体素基本具有相同的组织成分时，额叶和枕叶之间未发现Glu浓度存在显著区域差异（p = 0.23）。
与现有方法的比较
鉴于解剖区域和组织成分都可能导致大脑中Glu的变化，本研究方法旨在规避区分解剖区域和组织成分的困难。在相同解剖区域测量Glu浓度与组织成分的关系，同时在基本具有相同组织成分的两个区域之间进行区域差异比较。
结论
在脑皮质中，GM中的Glu水平显著高于WM。额叶和枕叶之间的Glu水平差异不显著。
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