OBJECTIVETo evaluate magnetic resonance (MR) Imaging and (1)H magnetic resonance spectroscopy ((1)HMRS) in the study of normal biochemical process of the brain, as well as differentiation of normal senile brain from cerebral diseases related to senility.

METHODSOne hundred and eighty healthy adult volunteers were selected for MR examination and 60 other healthy subjects for (1)HMRS examination. Ages of subjects ranged from 18 to 80 years. They were divided into six age groups. A 0.35 T superconductive MR system was used to perform MR examination. Point resolved spectroscopy sequence was required for (1)HMRS. The metabolites in the spectra included: N-acetylaspartate (NAA), choline compounds (CHO), creatine compounds (CR), myo-inositol (MI), glutamate and glutamine (Glu-n).

RESULTSIn 180 cases of MR, the shortest T(2) relaxation time occurred in the deep gray matter within the same age group while the length of T(1) relaxation time was ordered from low to high compared to age groups. T(2) relaxation time decreased as age increased. The peaks, ordered from high to low, were as follows in 60 cases of (1)HMRS: NAA, CR, CHO, MI, Glu-n. The ratios of NAA/CR and Glu-n/CR were higher in the senile age group, while that of MI/CR was lower. The ratio of CHO/CR was increased as age decreased. The ratio of NAA/CR and MI/CR gradually decreased in relation to movement from the anterior to the posterior part of the brain; the ratio of CHO/CR was highest in the occipital cortex. Correlation of T(1) relaxation time and partial metabolite ratios to age were present in gray matter.

CONCLUSIONSQuantitative studies of MR T(1) and T(2) relaxation times and (1)HMRS are essential to evaluation of normal myelinization processes, neuronal integrity and age-related biochemical changes in the brain.