Two-dimensional MR Spectroscopic Characterization of HE

描述（由申请人提供）：本申请的主要目标是评估局部二维（2D）磁共振光谱技术（MRS），并明确检测肝性脑病（HE）的脑代谢物。早期病变的发现对HE的诊断至关重要。局部磁共振光谱是表征人体组织中几种非侵入性代谢物的主要生化工具。优秀的一维（1D）磁共振光谱的HE和其他病理已经报道了有希望的结果。然而，各种代谢物的光谱重叠一直是传统1D mrs的主要问题。某些代谢物的光谱分析，即谷氨酸、谷氨酰胺、GABA、肌醇、天冬氨酸、谷胱甘肽，以及NAA和NAAG的天冬氨酸基团，在1.5T时严重重叠而变得复杂。2D MRS似乎很适合解决这个重叠问题。它彻底改变了核磁共振在生物大分子中的应用。其他研究人员之前尝试实现二维磁共振技术的局部版本主要使用幻影溶液，尽管一些结果报告来自动物大脑，使用非局部二维技术。除了1D MRS迄今为止已成功指定和分析的主要代谢物外，更多的代谢物尚未被检测到，并且它们在不同病理中的作用尚未被2D MRS探索。本工作要检验的主要假设是谷氨酰胺/谷氨酸、肌醇、天冬氨酸、与传统的1D mrs相比，在HE中使用局部2D COSY可以更明确地检测GABA和其他脑代谢物。本项目的三个具体目标是：1)获得HE患者前扣带和基底节区基于单体素的2D COSY光谱；2)记录HE患者全球pallidal Mill的变化；3)对HE患者进行神经精神和神经认知评价，并应用多因素回归分析MR表现与神经心理、血氨和肝功能检查结果的相关性。AGE 1.5T MRI扫描仪采用双侧表面“接收”线圈（MRI Devices Corp.）与身体射频“发射”线圈相结合，以实现改进的信号检测。最小的光谱重叠将减少谷氨酸/谷氨酰胺、GABA、肌醇、苏氨酸、葡萄糖、牛磺酸和谷胱甘肽的歧义分配和更好的定量，这将是这项工作的主要成果。

DESCRIPTION (provided by applicant): The major goals of this application are to evaluate a localized two-dimensional (2D) MR spectroscopic technique (MRS) and to detect cerebral metabolites unequivocally in hepatic encephalopathy (HE). Detection of early changes is very critical in the diagnosis of HE. Localized MR Spectroscopy is a major biochemical tool in characterizing noninvasively several metabolites in human tissues. Excellent one-dimensional (1D) MR spectra of HE and other pathologies have been reported with promising results. However, spectral overlap of various metabolites has been a major concern with the conventional 1D MRS. Spectral analysis of certain metabolites, namely glutamate, glutamine, GABA, myo-inositol, aspartate, glutathione, and the aspartyl groups of NAA and NAAG, has been complicated by severe overlap at 1.5T. 2D MRS seems well suited to address this problem of overlap. It has revolutionized the applications of NMR in biological macromolecules. Previous attempts by other researchers to implement the localized versions of the two-dimensional MR techniques mainly used phantom solutions, although some results were reported from animal brains using a non-localized 2D technique. In addition to the major metabolites successfully assigned and analyzed so far with 1D MRS, more metabolites are yet to be detected and their respective roles in different pathologiesare yet to be explored using 2D MRS. A major hypothesis to be tested in this work is whether the changes of glutamine/glutamate, myo-inositol, aspartate, GABA and other cerebral metabolites can be detected using the localized 2D COSY more unambiguously in HE than the conventional 1D MRS. Three specific goals of this project will be: 1) to acquire the single-voxel based 2D COSY spectra in the anterior cingulate and the basal ganglia regions of HE patients; 2) to record the global pallidal Mill changes in HE patients; 3) to perform the neuropsychiatric and neurocognitive assessment in HE patients, and to correlate the MR findings with the neuropsycho-logical, blood ammonia and liver function test results using multivariate regression analysis. AGE 1.5T MRI scanner with a bilateral surface "receive" coil (MRI Devices Corp.) in combination with a body rf "transmit" coil will be used to achieve improved signal detection. Minimal spectral overlap leading to less ambiguous assignment and better quantitation of glutamate/glutamine, GABA, myo-inositol, threonine, glucose, taurine and glutathione, will be a major outcome of this work.