Department of Radiology, University of Calgary, Calgary, AB, Canada.
Department of Psychiatry, University of Calgary, Calgary, AB, Canada.
Sci Rep. 2023 Feb 8;13(1):2246. doi: 10.1038/s41598-023-29190-y.
Single voxel magnetic resonance spectroscopy (MRS) quantifies metabolites within a specified volume of interest. MRS voxels are constrained to rectangular prism shapes. Therefore, they must define a small voxel contained within the anatomy of interest or include not of interest neighbouring tissue. When studying cortical regions without clearly demarcated boundaries, e.g. the dorsolateral prefrontal cortex (DLPFC), it is unclear how representative a larger voxel is of a smaller volume within it. To determine if a large voxel is representative of a small voxel placed within it, this study quantified total N-Acetylaspartate (tNAA), choline, glutamate, Glx (glutamate and glutamine combined), myo-inositol, and creatine in two overlapping MRS voxels in the DLPFC, a large (30×30x30 mm) and small (15×15x15 mm) voxel. Signal-to-noise ratio (SNR) and tissue type factors were specifically investigated. With water-referencing, only myo-inositol was significantly correlated between the two voxels, while all metabolites showed significant correlations with creatine-referencing. SNR had a minimal effect on the correspondence between voxels, while tissue type showed substantial influence. This study demonstrates substantial variability of metabolite estimates within the DLPFC. It suggests that when small anatomical structures are of interest, it may be valuable to spend additional acquisition time to obtain specific, localized data.
单体磁共振波谱（MRS）定量分析特定感兴趣容积内的代谢物。MRS 体素被限制为长方体形状。因此，它们必须定义一个包含在感兴趣解剖结构内的小体素，或者包含相邻但不感兴趣的组织。当研究没有明确边界的皮质区域，例如背外侧前额叶皮层（DLPFC）时，尚不清楚较大体素对其内部较小体积的代表性如何。为了确定较大体素是否代表位于其中的较小体素，本研究在 DLPFC 中定量测定了两个重叠 MRS 体素中的总 N-乙酰天冬氨酸（tNAA）、胆碱、谷氨酸、Glx（谷氨酸和谷氨酰胺的组合）、肌醇和肌酸，体素大小分别为 30×30x30mm 和 15×15x15mm。特别研究了信噪比（SNR）和组织类型因素。使用水参考，仅肌醇在两个体素之间具有显著相关性，而所有代谢物与肌酸参考均显示出显著相关性。SNR 对体素之间的一致性影响最小，而组织类型则具有较大影响。本研究表明 DLPFC 内代谢物估计值存在很大的可变性。它表明，当小的解剖结构是研究重点时，可能需要花费额外的采集时间来获得特定的、局部的数据，这是有价值的。
