The nuclear magnetic resonance (NMR) thermal control subsystem described in this paper is a newly developed platform-based thermal management solution. It presents critical challenges in system architecture design and core component selection. Therefore, it is necessary to carry out sufficient reliability design and verification work in the design and development stage to ensure its high quality and high reliability. Firstly, based on the statistical and analytical calculation of the client installation data of the benchmark product, the reliability metric of the new research subsystem is determined, and its usage and environmental profile are defined. Secondly, for the reliability metric to be verified, the test based on reliability growth and reliability demonstration is planned and implemented. A customized test platform is built, relevant reliability test parameters are designed, and a long-term test monitoring and recording mechanism is established to ensure the high-quality implementation of reliability tests. Finally, a detailed analysis is carried out on the design defects and failure modes exposed during the reliability test, and corresponding control measures are proposed to achieve the engineering goal of improving product robustness throughout its life cycle.
Equipment Design ; Magnetic Resonance Spectroscopy/instrumentation* ; Reproducibility of Results

In this paper, a new method of combining translation invariant (TI) and wavelet-threshold (WT) algorithm to distinguish weak and overlapping signals of proton magnetic resonance spectroscopy (1H-MRS) is presented. First, the 1H-MRS spectrum signal is transformed into wavelet domain and then its wavelet coefficients are obtained. Then, the TI method and WT method are applied to detect the weak signals overlapped by the strong ones. Through the analysis of the simulation data, we can see that both frequency and amplitude information of small-signals can be obtained accurately by the algorithm, and through the combination with the method of signal fitting, quantitative calculation of the area under weak signals peaks can be realized.
Algorithms ; Computer Simulation ; Magnetic Resonance Spectroscopy ; instrumentation ; methods ; Protons ; Signal Processing, Computer-Assisted ; Wavelet Analysis

To research on the effect of three different magnetic nanoparticles upon relaxation time of proton. The detection by magnetic resonance imaging (MRI) indicates that there is the effect of marked difference to right control experiment and to analyze the difference from theory. The result discloses that will be able to perform the experiment of molecular recognition using magnetic nanoparticles later.
Ferric Compounds ; chemistry ; Humans ; Magnetic Resonance Imaging ; instrumentation ; methods ; Magnetic Resonance Spectroscopy ; methods ; Magnetics ; Nanoparticles ; Protons

OBJECTIVETo investigate the effects of long-term low dose hormone replacement therapy (HRT) on postmenopausal women in hormone level, cognition score, hippocampus volume, and magnetic resonance spectroscopy (MRS) parameters.

METHODSA total of 182 postmenopausal women aged 50-87 years were chosen at Peking Union Medical College Hospital and assigned to HRT group and control group. The volunteers of HRT group had taken low dose hormone [estradiol (E2) 0.5-1.0 mg and progesterone 0.5-2.0 mg, once a day] for 4-33 years. The concentrations of E2, progesterone, and testosterone were measured using enzyme-linked immunosorbent assay (ELISA). The gene types of apolipoprotein E (ApoE) were measured by polymerase chain reaction, and the subjects with susceptible genes (ApoE epsilon3/epsilon4) of Alzheimer's disease (AD) were screened. Their hippocampus volumes and MRS parameters were obtained through magnetic resonance imaging (MRI), and results in two groups were analyzed by statistical method.

RESULTSCompared with control group, the concentrations of E2 at each age stage in HRT group were significantly higher (P < 0.05) except the 80-89 years old subgroup; yet, there were no statistical differences in the concentrations of progesterone and testosterone between the two groups. There was no obvious difference in ApoE subtypes distribution between the two groups. The results of hippocampus MRI for the subjects with susceptible genes ApoE epsilon3/epsilon4 (HRT group 14 cases, control group 11 cases) showed that the ratio of bilateral hippocampus volume to whole brain volume in HRT group (0.406 +/- 0.028) was significantly higher than control group (0.369 +/- 0.031, P < 0.05). The results of 1H MRS for the subjects with susceptible genes ApoE epsilon3/epsilon4 (HRT group 12 cases, control group 11 cases) showed that the N-acetylaspartate/total creatine at the area of hippocampus in HRT group (1.54 +/- 0.08) were significantly higher than control group (1.45 +/- 0.13, P < 0.05).

CONCLUSIONSFor postmenopausal women, long-term low dose HRT can maintain the physiological concentration of E2 in plasma. Furthermore, the hippocampus MRI performed on those with ApoE epsilon3/epsilon4 genes shows that long-term low dose HRT can prevent hippocampus atrophy, which is beneficial to maintain the brain function and prevent AD.

Aged ; Aged, 80 and over ; Alzheimer Disease ; prevention & control ; Apolipoprotein E3 ; genetics ; Aspartic Acid ; analogs & derivatives ; metabolism ; Creatine ; metabolism ; Dose-Response Relationship, Drug ; Estradiol ; administration & dosage ; metabolism ; Estrogen Replacement Therapy ; Female ; Hippocampus ; metabolism ; Humans ; Magnetic Resonance Spectroscopy ; instrumentation ; methods ; Middle Aged ; Postmenopause ; metabolism ; Progesterone ; administration & dosage ; metabolism ; Testosterone ; metabolism

OBJECTIVETo evaluate metabolic abnormalities in patients with mesial temporal lobe epilepsy (MTLE) with proton magnetic resonance spectroscopy (MRS) using a 3. 0T MR scanner.

METHODSSixty-three patients (32 women and 31 men) with diagnosed MTLE underwent diagnostic MR imaging (MRI) and proton MRS using a 3. 0T MR scanner. The clinical history and interictal epileptiform discharges (IEDs) were recorded. Sixteen healthy volunteers served as control. The results of proton MRS were compared with the findings of electroencephalogram and structural MRI findings.

RESULTSTwenty-seven of the 63 patients with MTLE showed unilateral hippocampal sclerosis, and 9 showed bilateral hippocampal sclerosis. The concentration ratio of N-acytelaspartate (NAA)/[creatine (Cr) + choline (Cho)] in the hippocampal region of MTLE patients (0.64 +/- 0.07) was significantly lower than control (0.80 +/- 0.05, P = 0.023). In the patients with unilateral hippocampal sclerosis, NAA/(Cr + Cho) in the hippocampal region ipsilateral to the sclerotic hippocampus (0.56 +/- 0.06) was significantly lower than the ratio in the contralateral hippocampal region (0.69 +/- 0.07, P < 0.001). There was significant difference in hippocampal NAA/(Cr + Cho) between the refractory patients and the non-refractory patients (0.64 +/- 0.05 vs. 0.71 +/- 0.07, P = 0.04). Forty-five patients were lateralized by IEDs, while 49 patients were lateralized by metabolite ratio. And lateralization determined by proton MRS and IEDs was concordant in 33 patients.

CONCLUSIONSMRS as a noninvasive tool adds helpful metabolite information to routine MRI in evaluation of MTLE. The method is well established and should be a routine clinical application in the investigation of epilepsy.

Adult ; Aspartic Acid ; analogs & derivatives ; metabolism ; Choline ; metabolism ; Creatine ; metabolism ; Electroencephalography ; Epilepsy, Temporal Lobe ; metabolism ; Female ; Hippocampus ; metabolism ; Humans ; Magnetic Resonance Imaging ; Magnetic Resonance Spectroscopy ; instrumentation ; methods ; Male ; Protons

With the development of magnetic resonance (MR) technology, the concern is focused on molecular and physiological imaging besides structural information. Ultra high field MR scanner shows great superiority. 3. 0-T MR scanners provide almost two-fold signal-to-noise ratio (SNR) compared with a standard 1. 5-T MR scanner. The higher baseline SNR can be converted into a variety of alternative benefits. There are still some other changes brought about by 3. 0-T, such as higher sensitivity to motion, susceptibility effect, more difference in resonant frequency among different metabolites, and so on. These features may be a double-edged sword in structural and functional imaging. But with the ceaseless progress of the technology and gains in experience, 3. 0-T systems will provide more information and show more advantages.
Animals ; Humans ; Image Enhancement ; methods ; Magnetic Resonance Imaging ; instrumentation ; methods ; Magnetic Resonance Spectroscopy ; instrumentation ; Sensitivity and Specificity