[Age-dependent changes in metabolites of the normal brain in childhood : observation by proton MR spectroscopy]

We investigated aging-dependent changes in proton magnetic resonance spectroscopy (1H-MRS) of the normal brain in childhood, and observed differences in the four portions of the brain. Measurement by 1H-MRS was carried out on the frontal lobe, parietotemporal lobe, temporal lobe and cerebellum. The NAA/Cho ratio increased rapidly in the period from 0 to 2 years of age in all portions except for the cerebellum, and gradually increased after three years of age. The number of measurements of the cerebellum was not sufficient to reach a conclusion, but no clear aging-related change was found. The Cho/Cr ratio decreased according to the neural development in all portions except the cerebellum. Because the T2 relaxation time of water after four years of age was almost the same as that of young adults, we used the relaxation times specified in the literature to quantify the metabolites observed by 1H-MRS. The subjects used for quantification were aged from 4 to 12 years. The concentration of NAA in the temporal lobe was the lowest of the four portions, and that of Cho and Cr in the cerebellum was the highest in four portions. These results could not be obtained by signal ratios alone, and we considered that the quantification of metabolites is necessary for a better understanding of 1H-MRS. This study showed that the results of 1H-MRS vary depending on age and the portion in the brain. Our results may serve as a normal basis for the detection of pathological changes by 1H-MRS.