Quantification of metabolites from single-voxel in vivo H-1 NMR data of normal human brain by means of time-domain data analysis

We present here a combination of time-domain signal analysis procedures for quantification of human brain in vivo H-1 NMR spectroscopy (MRS) data. The method is based on a separate removal of a residual water resonance followed by a frequency-selective time-domain Line-shape fitting analysis of metabolite signals. Calculation of absolute metabolite concentrations was based on the internal water concentration as a reference. The estimated average metabolite concentrations acquired from six regions of normal human brain with a single-voxel spin-echo technique for the N-acetylaspartate, creatine, and choline-containing compounds were 11.4 +/- 1.0, 6.5 +/- 0.5, and 1.7 +/- 0.2 mmol kg(-1) wet weight, respectively. The time-domain analyses of in vivo H-1 MRS data from different brain regions with their specific characteristics demonstrate a case in which the use of frequency-domain methods pose serious difficulties.