Bell Tiffany K, Goerzen Dana, Near Jamie, Harris Ashley D
Deparment of Radiology, University of Calgary, Calgary, Canada; Hotchkiss Brain Institute. Calgary, Canada; Alberta Children's Hospital Research Institute, Calgary, Canada; School of Psychology and Clinical Language Sciences, University of Reading, Reading, UK.
Weill Cornell Medicine, Cornell University.
J Neurosci Methods. 2025 Nov;423:110523. doi: 10.1016/j.jneumeth.2025.110523. Epub 2025 Jun 30.
Proton magnetic resonance spectroscopy (MRS) can be used to quantify multiple neurometabolites. However, due to the difficulty of separating overlapping signals at the commonly used field strength of 3 T, the quantified values are often composites of metabolically related chemicals. This can complicate interpretation and mask effects of interest. Therefore, it is important to determine the ability to accurately separate these signals at 3 T. Data acquired at 7 T can provide a benchmark, as higher field strength facilitates spectral resolution and reduces the signal overlap.
This study assessed the ability of multiple 3 T MRS sequences to separate the commonly acquired neurochemicals (Glutamate (Glu) and Glutamine (Gln); N-Acetyl aspartate (NAA) and N-acetylaspartylglutamate (NAAG); Creatine (Cr) and Phosphocreatine (PCr); Choline (Cho), Phosphocholine (PC) and Glycerophosphocholine (GPC)). We compared metabolites quantified at 3 T from 6 acquisitions (PRESS, TE= 20, 30, 40, 80 ms, semi-LASER, TE=28 ms and STEAM TE=6 ms) with those quantified at 7 T using STEAM (TE=8 ms).
Sequences with short echo times (STEAM-6, PRESS-20) generally performed better at separating most metabolites when using correlative and difference analyses with 7 T reference data. The exceptions were NAAG, which was best quantified with PRESS-80, and Cr and PCr, which were not well separated by any sequence.
When wanting to specifically separate composite metabolite signals using single voxel MRS, shorter echo times generally perform better. Researchers should be mindful of the effects of acquisition parameters on the metabolite measures.
质子磁共振波谱（MRS）可用于定量多种神经代谢物。然而，由于在常用的3T场强下分离重叠信号存在困难，定量值通常是代谢相关化学物质的复合物。这可能会使解释复杂化并掩盖感兴趣的效应。因此，确定在3T下准确分离这些信号的能力很重要。在7T下获取的数据可以提供一个基准，因为更高的场强有助于提高光谱分辨率并减少信号重叠。
本研究评估了多个3T MRS序列分离常见神经化学物质（谷氨酸（Glu）和谷氨酰胺（Gln）；N-乙酰天门冬氨酸（NAA）和N-乙酰天门冬氨酰谷氨酸（NAAG）；肌酸（Cr）和磷酸肌酸（PCr）；胆碱（Cho）、磷酸胆碱（PC）和甘油磷酸胆碱（GPC））的能力。我们将6次采集（PRESS，TE = 20、30、40、80 ms，半激光，TE = 28 ms和STEAM TE = 6 ms）在3T下定量的代谢物与使用STEAM（TE = 8 ms）在7T下定量的代谢物进行了比较。
当使用与7T参考数据的相关性和差异分析时，短回波时间的序列（STEAM-6、PRESS-20）在分离大多数代谢物方面通常表现更好。例外情况是NAAG，用PRESS-80能最好地定量，以及Cr和PCr，没有任何序列能很好地分离它们。
当想用单体素MRS特异性分离复合代谢物信号时，较短的回波时间通常表现更好。研究人员应注意采集参数对代谢物测量的影响。
