Objective To 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 ce...Objective To 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. Methods One 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). Results In 180 cases of MR, the shortest T2 relaxation time occurred in the deep gray matter within the same age group while the length of T1 relaxation time was ordered from low to high compared to age groups. T2 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 T1 relaxation time and partial metabolite ratios to age were present in gray matter.Conclusions Quantitative studies of MR T1 and T2 relaxation times and 1 HMRS are essential to evaluation of normal myelinization processes, neuronal integrity and age-related biochemical changes in the brain.展开更多
C NMR spin-lattice relaxation times (T1), line widths, nuclear Overhauser effects (NOE) at room temperature have been measured for radiated ets 1,4-polybutadiene.With the increase of radiation dose T1 is almost invari...C NMR spin-lattice relaxation times (T1), line widths, nuclear Overhauser effects (NOE) at room temperature have been measured for radiated ets 1,4-polybutadiene.With the increase of radiation dose T1 is almost invariant, but line width of the methylene (-CH2-) carbon increases remarkably, and its NOE factor decreases sharply. This implies that the long-range segmental motion is hindered, and saturated tertiary carbon (-C H- ) is formed during crosslinking of ets 1,4-polybutadiene.展开更多
文摘Objective To 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. Methods One 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). Results In 180 cases of MR, the shortest T2 relaxation time occurred in the deep gray matter within the same age group while the length of T1 relaxation time was ordered from low to high compared to age groups. T2 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 T1 relaxation time and partial metabolite ratios to age were present in gray matter.Conclusions Quantitative studies of MR T1 and T2 relaxation times and 1 HMRS are essential to evaluation of normal myelinization processes, neuronal integrity and age-related biochemical changes in the brain.
文摘C NMR spin-lattice relaxation times (T1), line widths, nuclear Overhauser effects (NOE) at room temperature have been measured for radiated ets 1,4-polybutadiene.With the increase of radiation dose T1 is almost invariant, but line width of the methylene (-CH2-) carbon increases remarkably, and its NOE factor decreases sharply. This implies that the long-range segmental motion is hindered, and saturated tertiary carbon (-C H- ) is formed during crosslinking of ets 1,4-polybutadiene.
