School of Health Sciences, Faculty of Health and Medicine, University of Newcastle, Callaghan, NSW 2308, Australia; Hunter Medical Research Institute, Kookaburra Circuit, New Lambton Heights, NSW 2305, Australia.
Department of Neurology, John Hunter Hospital, Lookout Road, New Lambton Heights, NSW 2305, Australia.
Eur J Radiol. 2018 Nov;108:107-113. doi: 10.1016/j.ejrad.2018.09.020. Epub 2018 Sep 17.
This study was designed to evaluate the diurnal stability and long-term repeatability and reliability of one-dimensional (1D) hydrogen magnetic resonance spectroscopy (1H-MRS) in vitro and in vivo at 3 T.
A standard brain phantom was used for in vitro study. In vivo diurnal evaluation involved ten healthy subjects, while repeatability study involved six subjects. MRS was acquired from posterior cingulate gyrus (PCG), and processed with LCModel. Diurnal effects were assessed with repeated measures ANOVAs, repeatability was evaluated using coefficient of variation (CV), while reliability was assessed with standard error measurement (SEM) and intra-class correlation coefficient (ICC).
Diurnal metabolic changes in vitro were non-significant. The intra/inter-in vitro CVs for the major metabolites; N-acetylaspartate (NAA), creatine (Cr), myo-inositol (mI), glutamate + glutamine (Glx) and total choline (tCho) were 1-3%/2-6%, respectively. Statistically significant in vivo diurnal effects were only seen for glycerophosphocholine (GPC, +10%, F = 10.6, p = 0.001) and Glx (+6%, F = 5.1, p = 0.018). The intra/inter-subject CVs for the major metabolites ranged from 2-5%/ 5-9%, respectively. The major metabolites displayed ICC ranging from 0.5-0.7 and low SEM (0.001-0.078) reflecting high reliability in detecting neurometabolites. The inter-week interval for in vivo measurements had minimal effect on metabolite ratios (F = 1.4, p = 0.09).
In vitro MRS showed no diurnal effects and minimal variation in metabolite levels. Most PCG metabolites are not altered diurnally. The low in vivo variability of metabolite concentration supports the use of localised MRS on clinical 3 T scanners for reliable neurometabolic profiling of the brain.
本研究旨在评估一维（1D）氢磁共振波谱（1H-MRS）在 3T 下的体外和体内的日间稳定性和长期可重复性和可靠性。
使用标准脑模型进行体外研究。体内日间评估涉及 10 名健康受试者，而重复性研究涉及 6 名受试者。MRS 从后扣带回（PCG）采集，并使用 LCModel 进行处理。使用重复测量方差分析评估日间影响，使用变异系数（CV）评估可重复性，使用标准误差测量（SEM）和组内相关系数（ICC）评估可靠性。
体外代谢物的日间变化无显著性。主要代谢物 N-乙酰天冬氨酸（NAA）、肌酸（Cr）、肌醇（mI）、谷氨酸+谷氨酰胺（Glx）和总胆碱（tCho）的内/间体外 CV 分别为 1-3%/2-6%。仅在体内甘油磷酸胆碱（GPC，+10%，F=10.6，p=0.001）和 Glx（+6%，F=5.1，p=0.018）出现统计学上显著的日间效应。主要代谢物的内/间个体 CV 范围分别为 2-5%/5-9%。主要代谢物的 ICC 范围为 0.5-0.7，SEM 低（0.001-0.078），表明检测神经代谢物的可靠性高。体内测量的两周间隔对代谢物比值的影响最小（F=1.4，p=0.09）。
体外 MRS 无昼夜影响，代谢物水平变化最小。大多数 PCG 代谢物昼夜不变。代谢物浓度的体内变异性低支持在临床 3T 扫描仪上进行局部 MRS，以可靠地进行大脑神经代谢谱分析。
