Human Brain Proton Metabolite Mapping at Short TE

描述（由申请人提供）： 在短TE下通过高场磁共振（MR）光谱成像（MRSI）获得的质子代谢物的定量中的主要问题是将代谢物共振与不均匀和变化的基线分离。一些基线波动是由于体积外的水和脂质信号，而其他变化是由于大分子的存在，我们提出了一系列措施，以提高分离代谢物和基线的能力。信号，其中最重要的包括在不同TE时间获得一系列中等信噪比（S/N）谱，该谱具有包括紧密间隔的180度脉冲的序列（CP脉冲序列）这保留了不同TE值处强耦合共振的谱图，即使信号幅度由于T2弛豫而衰减预期光谱组的同时拟合使得能够改进代谢物信号与基线的分离，并且提供代谢物共振面积的更可靠的估计。许多额外的措施包括1）改进的RF脉冲，包括双曲正割脉冲的改进和对CP脉冲串的B1不均匀性具有免疫力的自旋回波脉冲级联，2）改进的匀场方法，3）改进的MRSI采集序列，4）改进的代谢物谱处理方法，和5）基于与组织分段结构MRI数据的共分析，计划改进机构单位中的代谢物定量。最后，将开发正常大脑的代谢物图谱，反映区域代谢物水平和变化。脉冲、数据和信息，以加强这两个地点的研究。

DESCRIPTION (provided by applicant): A major problem in quantification of proton metabolites obtained by high field magnetic resonance (MR) spectroscopic imaging (MRSI) at short TE is separating the metabolite resonances from the uneven and varying baseline Some of the baseline fluctuations are due to out-of-volume water and lipid signals, while other variations are due to the presence of macromolecules We propose a series of measures to improve the ability to separate metabolite and baseline signals, the most important of which involves obtaining a series of moderate signal-to noise (S/N) spectra at differing TE times with a sequence that includes closely spaced 180 degrees pulses (CP pulse train) to reduce J evolution for strongly coupled spins prior to acquisition This preserves the spectral patterns for strongly coupled resonances at the different TE values even though the signal amplitudes decay due to T2 relaxation Simultaneous fitting of the suite of spectra is expected to enable improved separation of metabolite signals from baseline, and to provide more reliable estimates of metabolite resonance areas A number of additional measures including 1) improved RF pulses, including improvement of hyperbolic secant pulses and a spin echo pulse cascade with immunity to B1 inhomogenicity for the CP pulse train, 2) improved methods of shimming, 3) improved MRSI acquisition sequences, 4) improved methods for processing of metabolite spectra, and 5) improvements for metabolite quantification in institutional units, based on coanalysis with tissue segmented structural MRI data, are planned Finally, a metabolite atlas of normal brain, reflecting regional metabolite levels and variations, will be developed This proposal is coordinated with the partner IRPG proposal for sharing of programs, pulses, data, and information to enhance the research at both sites.