Department of Radiology, University of Calgary, Calgary, Canada.
Hotchkiss Brain Institute and Alberta Children's Hospital Research Institute, Calgary, Canada.
NMR Biomed. 2021 May;34(5):e4245. doi: 10.1002/nbm.4245. Epub 2020 Jan 28.
In vivo quantification of glutamate (Glu) and γ-aminobutyric acid (GABA) using MRS is often achieved using two separate sequences: a short-echo point resolved spectroscopy (PRESS) acquisition for Glu and a Mescher-Garwood PRESS (MEGA-PRESS) acquisition for GABA. The purpose of this study was to examine the agreement of Glu and Glx (the combined signal of glutamate + glutamine) quantified from two different GABA-edited MEGA-PRESS acquisitions (GABA plus macromolecules, GABA+, T = 68 ms, and macromolecule suppressed, MMSup, T = 80 ms) with Glu and Glx quantified from a short-echo PRESS (PRESS-35, T = 35 ms) acquisition. Fifteen healthy male volunteers underwent a single scan session, in which data were acquired using the three acquisitions (GABA+, MMSup and PRESS-35) in both the sensorimotor and anterior cingulate cortices using a voxel size of 3 × 3 × 3 cm . Glx and Glu were quantified from the MEGA-PRESS data using both the OFF sub-spectra and the difference (DIFF) spectra. Agreement was assessed using correlation analyses, Bland-Altman plots and intraclass correlation coefficients. Glx quantified from the OFF sub-spectra from both the GABA+ and MMSup acquisitions showed poor agreement with PRESS-35 in both brain regions. In the sensorimotor cortex, Glu quantified from the OFF sub-spectra of GABA+ showed moderate agreement with PRESS-35 data, but this finding was not replicated in the anterior cingulate cortex. Glx and Glu quantified using the DIFF spectra of either MEGA-PRESS sequence were in poor agreement with the PRESS-35 data in both brain regions. In conclusion, Glx and Glu measured from MEGA-PRESS data generally showed poor agreement with Glx and Glu measured using PRESS-35.
使用 MRS 对谷氨酸 (Glu) 和 γ-氨基丁酸 (GABA) 进行体内定量分析通常采用两种独立的序列：一种是短回波点分辨波谱 (PRESS) 采集用于 Glu，另一种是 Mesche-Garwood PRESS (MEGA-PRESS) 采集用于 GABA。本研究旨在探讨两种不同 GABA 编辑的 MEGA-PRESS 采集（GABA 加大分子，GABA+，T = 68 ms 和大分子抑制，MMSup，T = 80 ms）中定量的 Glu 和 Glx（谷氨酸+谷氨酰胺的组合信号）与短回波 PRESS（PRESS-35，T = 35 ms）采集定量的 Glu 和 Glx 的一致性。15 名健康男性志愿者进行了单次扫描，在该扫描中，使用三种采集方法（GABA+、MMSup 和 PRESS-35）在感觉运动皮质和前扣带回皮质中采集数据，体素大小为 3×3×3cm。使用 OFF 子谱和差值（DIFF）谱从 MEGA-PRESS 数据中定量 Glx 和 Glu。通过相关分析、Bland-Altman 图和组内相关系数评估一致性。来自 GABA+和 MMSup 采集的 OFF 子谱定量的 Glx 在两个脑区与 PRESS-35 的一致性均较差。在感觉运动皮质中，来自 GABA+OFF 子谱的 Glu 与 PRESS-35 数据具有中度一致性，但在前扣带回皮质中并未复制这一发现。使用两种 MEGA-PRESS 序列的 DIFF 谱定量的 Glx 和 Glu 与 PRESS-35 数据在两个脑区均一致性较差。总之，来自 MEGA-PRESS 数据的 Glx 和 Glu 测量值与使用 PRESS-35 测量值的 Glx 和 Glu 测量值一般一致性较差。
