THE CONCENTRATION OF N-ACETYL ASPARTATE, CREATINE PLUS 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 S TEAM experiment to calculate the concentrations of the metabolites: N- acetyl aspartate (NAA), creatine + phosphocreatine (Cr + PCr), and cho line (Cho) containing compounds in four different parts of the brain i n 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 an d signal ratios: NAA/Cho, NAA/Cr + PCr, and Cho/Cr + PCr at TE = 272 m sec 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 gro up, the concentration of NAA wag significantly higher in the occipital part than in the other three parts of the brain. No significant regio nal 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 si gnificant regional or age dependent variation was found concerning the T1 and T2 relaxation times.