The concentration of N-acetyl aspartate, creatine + phosphocreatine, and choline in different parts of the brain in adulthood and senium.

The fully relaxed water signal was used as an internal standard in a STEAM experiment to calculate the concentrations of the metabolites: N-acetyl aspartate (NAA), creatine + phosphocreatine (Cr + PCr), and choline (Cho) containing compounds in four different parts of the brain in two age groups of healthy volunteers (20-30 yr, n = 8) and (60-80 yr, n = 8). Furthermore, T1 and T2 relaxation time of the metabolites and signal ratios: NAA/Cho, NAA/Cr + PCr, and Cho/Cr + PCr at TE = 272 msec were calculated. The experiments were carried out using a Siemens Helicon SP 63/84 wholebody MR-scanner at 1.5 T. In the younger age group, the concentration of NAA was significantly higher in the occipital part than in the other three parts of the brain. No significant regional variation was found for any other metabolite concentration. There was a significantly higher concentration of NAA in the occipital part of the brain in the younger age group compared to the older one. No significant regional or age dependent variation was found concerning the T1 and T2 relaxation times.