Department of Biological and Medical Psychology, University of Bergen, Bergen, Norway.
Mohn Medical Imaging and Visualization Centre (MMIV), Haukeland University Hospital, Bergen, Norway.
Hum Brain Mapp. 2024 Jan;45(1):e26531. doi: 10.1002/hbm.26531. Epub 2023 Nov 20.
Magnetic resonance spectroscopy (MRS) is the primary method that can measure the levels of metabolites in the brain in vivo. To achieve its potential in clinical usage, the reliability of the measurement requires further articulation. Although there are many studies that investigate the reliability of gamma-aminobutyric acid (GABA), comparatively few studies have investigated the reliability of other brain metabolites, such as glutamate (Glu), N-acetyl-aspartate (NAA), creatine (Cr), phosphocreatine (PCr), or myo-inositol (mI), which all play a significant role in brain development and functions. In addition, previous studies which predominately used only two measurements (two data points) failed to provide the details of the time effect (e.g., time-of-day) on MRS measurement within subjects. Therefore, in this study, MRS data located in the anterior cingulate cortex (ACC) were repeatedly recorded across 1 year leading to at least 25 sessions for each subject with the aim of exploring the variability of other metabolites by using the index coefficient of variability (CV); the smaller the CV, the more reliable the measurements. We found that the metabolites of NAA, tNAA, and tCr showed the smallest CVs (between 1.43% and 4.90%), and the metabolites of Glu, Glx, mI, and tCho showed modest CVs (between 4.26% and 7.89%). Furthermore, we found that the concentration reference of the ratio to water results in smaller CVs compared to the ratio to tCr. In addition, we did not find any time-of-day effect on the MRS measurements. Collectively, the results of this study indicate that the MRS measurement is reasonably reliable in quantifying the levels of metabolites.
磁共振波谱（MRS）是一种可以测量活体脑内代谢物水平的主要方法。为了使其在临床应用中具有可靠性，需要进一步明确其测量的可靠性。尽管有许多研究探讨了γ-氨基丁酸（GABA）的可靠性，但相对较少的研究探讨了谷氨酸（Glu）、N-乙酰天门冬氨酸（NAA）、肌酸（Cr）、磷酸肌酸（PCr）或肌醇（mI）等其他脑代谢物的可靠性，这些代谢物在脑发育和功能中都起着重要作用。此外，以前的研究主要使用两次测量（两个数据点），未能提供时间效应（例如，一天中的时间）对被试内 MRS 测量的细节。因此，在这项研究中，我们在 1 年内重复记录了前扣带回皮层（ACC）的 MRS 数据，每个被试至少进行了 25 次测量，目的是通过使用变异系数（CV）指数来探索其他代谢物的变异性；CV 越小，测量结果越可靠。我们发现 NAA、tNAA 和 tCr 的代谢物的 CV 最小（1.43%到 4.90%），Glu、Glx、mI 和 tCho 的代谢物的 CV 中等（4.26%到 7.89%）。此外，我们发现与 tCr 相比，以水为参照的比值的浓度参考会导致更小的 CV。此外，我们没有发现 MRS 测量存在任何时间效应。总的来说，这项研究的结果表明，MRS 测量在定量代谢物水平方面具有相当的可靠性。
