Change of the brain proton magnetic resonance spectroscopy metabolite’s ratios with aging

Background: Proton magnetic resonance spectroscopy (HMRS) is a noninvasive diagnostic method, which allows for assessment of tissue concentrations of metabolites. The aim of our study was to analyze the ratios of metabolite signals in HMRS within the brain in the healthy population and correlate them with age.
Material/Methods: We studied prospectively 90 subjects aged from 8 to 80 years without neurologic symptoms and abnormalities in MR imaging. In all patients, brain HMRS with SignaHDx 1.5T was performed with the PRESS sequence using a single voxel, at an echo time of 35 milliseconds and a repetition time of 1500 milliseconds. Spectroscopic evaluation involved voxels placed in the grey matter of the posterior cingulate gyrus (PGM) and the white matter of the parietal lobe (PWM). Based on the intensity of N-acetylaspartate (NAA), creatine (Cr), choline (Cho), myoinositol (mI), and water signals, the ratios of the signals of different combinations of metabolites were calculated. We evaluated correlations of these metabolites’ ratios with age.
Results: We found statistically significant correlations with age of the ratios of the examined metabolites (α=0.05), resulting mainly from a decrease in NAA with age in both PGM and PWM. In PGM there were negative correlations with age for NAA/Cr, NAA/H2O, Cr/H2O, and mI/H2O ratios, while the correlation was positive for Cho/NAA and mI/NAA. In the case of PWM, we found negative correlations with age for NAA/Cr and NAA/H2O, while the correlations were positive for mI/NAA and Cho/NAA ratios.
Conclusions: There are statistically significant correlations between age and metabolite ratios detected by HMRS in the healthy aging human brain. NAA concentration has the greatest influence on these correlations.

Keywords: Magnetic Resonance Spectroscopy, Aging, Brain, metabolites