Toward an in Vivo Neurochemical Profile: Quantification of 18 Metabolites in Short-Echo-Time 1H NMR Spectra of the Rat Brain

✍ Scribed by Josef Pfeuffer; Ivan Tkáč; Stephen W. Provencher; Rolf Gruetter

• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 203 KB
• Volume: 141
• Category: Article
• ISSN: 1090-7807
• DOI: 10.1006/jmre.1999.1895

✦ Synopsis

Localized in vivo 1 H NMR spectroscopy was performed with 2-ms echo time in the rat brain at 9.4 T. Frequency domain analysis with LCModel showed that the in vivo spectra can be explained by 18 metabolite model solution spectra and a highly structured background, which was attributed to resonances with fivefold shorter in vivo T 1 than metabolites. The high spectral resolution (full width at half maximum approximately 0.025 ppm) and sensitivity (signal-to-noise ratio approximately 45 from a 63-L volume, 512 scans) was used for the simultaneous measurement of the concentrations of metabolites previously difficult to quantify in 1 H spectra. The strongly represented signals of Nacetylaspartate, glutamate, taurine, myo-inositol, creatine, phosphocreatine, glutamine, and lactate were quantified with Crame ´r-Rao lower bounds below 4%. Choline groups, phosphorylethanolamine, glucose, glutathione, ␥-aminobutyric acid, Nacetylaspartylglutamate, and alanine were below 13%, whereas aspartate and scyllo-inositol were below 22%. Intra-assay variation was assessed from a time series of 3-min spectra, and the coefficient of variation was similar to the calculated Crame ´r-Rao lower bounds. Interassay variation was determined from 31 pooled spectra, and the coefficient of variation for total creatine was 7%. Tissue concentrations were found to be in very good agreement with neurochemical data from the literature.