National Institute of Mental Health, Bethesda, MD, United States of America.
National Institute of Neurological Disorders and Stroke, Bethesda, MD, United States of America.
PLoS One. 2021 Mar 18;16(3):e0248632. doi: 10.1371/journal.pone.0248632. eCollection 2021.
Abnormal cell membrane metabolism is associated with many neuropsychiatric disorders. Free phosphomonoesters and phosphodiesters, which can be detected by in vivo 31P magnetic resonance spectroscopy (MRS), are important cell membrane building blocks. However, the quantification of phosphoesters has been highly controversial even in healthy individuals due to overlapping signals from macromolecule membrane phospholipids (MP). In this study, high signal-to-noise ratio (SNR) cerebral 31P MRS spectra were acquired from healthy volunteers at both 3 and 7 Tesla. Our results indicated that, with minimal spectral interference from MP, the [phosphocreatine (PCr)]/[phosphocholine (PC) + glycerophosphocholine (GPC)] ratio measured at 7 Tesla agreed with its value expected from biochemical constraints. In contrast, the 3 Tesla [PCr]/[PC+GPC] ratio obtained using standard spectral fitting procedures was markedly smaller than the 7 Tesla ratio and than the expected value. The analysis suggests that the commonly used spectral model for MP may fail to capture its complex spectral features at 3 Tesla, and that additional prior knowledge is necessary to reliably quantify the phosphoester signals at low magnetic field strengths when spectral overlapping is significant.
细胞膜代谢异常与许多神经精神疾病有关。可通过体内 31P 磁共振波谱（MRS）检测到的游离磷酸单酯和磷酸二酯是重要的细胞膜组成部分。然而，即使在健康个体中，由于大分子膜磷脂（MP）的信号重叠，磷酸酯的定量也存在很大争议。在这项研究中，我们在 3 和 7 特斯拉下从健康志愿者中获得了具有高信噪比（SNR）的脑 31P MRS 谱。我们的结果表明，在最小化 MP 光谱干扰的情况下，在 7 特斯拉下测量的[磷酸肌酸（PCr）]/[磷酸胆碱（PC）+甘油磷酸胆碱（GPC）]比值与生化限制所预期的值一致。相比之下，使用标准光谱拟合程序获得的 3 特斯拉[PCr]/[PC+GPC]比值明显小于 7 特斯拉比值和预期值。该分析表明，在 3 特斯拉下，常用的 MP 光谱模型可能无法捕捉其复杂的光谱特征，并且当光谱重叠显著时，需要额外的先验知识来可靠地定量低磁场强度下的磷酸酯信号。
