Quantitative Mapping of the Cerebral Glutamate Concentrations Using Fast Magnetic Resonance Spectroscopic Imaging Technique

Glutamate (Glu) as the most prevalent excitatory neurotransmitter in the brain plays important role in many clinical researches. The quantification of Glu itself in MR spectrum is difficult duo to its complex spectral shape and overlapping with other metabolites especially Glutamine. TE averaged (TE-avg) method is proposed to simplify the Glu quantification while minimize the Gln contribution which offer a potential opportunity to extract Glu content alone. The trade off is the need to collection of multiple spectra TE raging from 35 ms to 185 ms. A general setting of 16 TEs cost 16 times more scan time for each scan which lowers the clinical potential of TE-avg method as for MRSI is desired. This project is aimed to build up a MRSI method to access the concentrations of Glu in the brain with clinical applicability. The MRSI protocol will be based on fast MRSI technique, PEPSI, to speed up the data acquisition and to increase the spatial information and will also adopt TE-avg method to simplify the quantification complexity of Glu and thus increase the reliability of quantification. For the clinical use the protocol will achieve following properties; 1) clinical acceptable acquisition time. 2) coverage for whole brain area in 2D slice. 3) better spatial resolution than conventional MRSI. 4) Feasible for multiple slice orientation. 5) ability for longitudinal and inter subject comparison. The optimized TE-avg PEPSI protocol will be proposed through MRS simulation using GAVA. The improvement in Glu quantification with proposed TE-avg PEPSI protocol will be verified using LCModel with basis generated through GAVA simulation. The inter subject and inter scan variance will be examined with proper scaling procedures to the quantified metabolic concentrations. Established TE-avg PEPSI will be sued to investigate the regional distribution of Glu in het normal brain. The achievement of this project will open up clinical research such as longitudinal effects of drug therapy and drug monitoring, long term alternation for patients with neuronal disorder diseases.

Project ID:PB10007-7261
External Project ID:NSC100-2320-B004-002