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NMR Biomed. 2018 Jan;31(1). doi: 10.1002/nbm.3837. Epub 2017 Nov 3.

In vivo detection and automatic analysis of GABA in the mouse brain with MEGA-PRESS at 9.4 T.

Author information

1
Department of Biomedical Engineering, Columbia University, New York, NY, USA.
2
Bruker BioSpin, Billerica, MA, USA.
3
Herbert Irving Comprehensive Cancer Center, Columbia University Medical Center, New York, NY, USA.
4
Departments of Neurology, Radiology, and Psychiatry, Columbia University College of Physicians and Surgeons, New York, NY, USA.
5
Departments of Diagnostic Radiology and Biomedical Engineering, Yale University, New Haven, CT, USA.

Abstract

The goals of this study were to develop an acquisition protocol and the analysis tools for Meshcher-Garwood point-resolved spectroscopy (MEGA-PRESS) in mouse brain at 9.4 T, to allow the in vivo detection of γ-aminobutyric acid (GABA) and to examine whether isoflurane alters GABA levels in the thalamus during anesthesia. We implemented the MEGA-PRESS sequence on a Bruker 94/20 system with ParaVision 6.0.1, and magnetic resonance spectra were acquired from nine male wild-type C57BL/6 J mice at the thalamus. Four individual scans were obtained for each mouse in a 2-h time course whilst the mouse was anesthetized with isoflurane. We developed an automated analysis program with improved correction for frequency and phase drift compared with the standard creatine (Cr) fitting-based method and provided automatic quantification. During MEGA-PRESS acquisition, a single voxel with a size of 5 × 3 × 3 mm3 was placed at the thalamus to evaluate GABA to Cr (GABA/Cr) ratios during anesthesia. Detection and quantitative analysis of thalamic GABA levels were successfully achieved. We noticed a significant decrease in GABA/Cr during the 2-h anesthesia (by linear regression analysis: slope < 0, p < 0.0001). In summary, our findings demonstrate that MEGA-PRESS is a feasible technique to measure in vivo GABA levels in the mouse brain at 9.4 T.

KEYWORDS:

GABA; J-difference editing; MEGA-PRESS; anesthesia; magnetic resonance spectroscopy; mouse; quantification; thalamus

PMID:
29105210
DOI:
10.1002/nbm.3837
[Indexed for MEDLINE]

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