Regional apparent metabolite concentrations in young adult brain measured by ¹H MR spectroscopy at 3 Tesla

Purpose: To quantify and examine the distribution of brain metabolites in normal young adults using single voxel MR spectroscopy at 3 Tesla (T). Materials and Methods: Short-echo time single-voxel PRESS technique was used to measure the apparent concentration of five metabolites at nine locations in the brains of young adults. Concentrations were estimated by means of an automated fitting method (LCModel) with reference to an unsuppressed water signal and were corrected for T₁ relaxation, T₂ relaxation, and cerebrospinal fluid partial volume. Analysis of variance with Tukey post hoc test was used to evaluate regional variations. Results: Statistically significant differences in regional concentrations were detected for each of the metabolites. The number of significant differences was greatest for total choline, whereas myo-inositol and the sum of glutamine and glutamate had the fewest. Magnitude of variation was greatest for total choline and least for the sum of N-acetyl aspartate and N-acetylaspartylglutamate. Conclusion: In agreement with previous studies at other field strengths, we found heterogeneous distribution of the major spectroscopically measurable brain metabolites. Although the most distinct differences are between tissue types, there is appreciable variation within a tissue type at different locations. The spectra and metabolite concentrations presented should provide a useful reference for both clinical and research MR spectroscopy studies performed at 3T.