Test-retest precision of brain metabolites in healthy participants using 31P-MRS and 1H MEGA-PRESS on a 3T multi-nuclear MRI system.

BACKGROUND

Magnetic resonance spectroscopy (MRS) enables the non-invasive quantification of brain metabolites, and its reliability is crucial for accurate interpretation of disease state. This study assessed the test-retest precision of phosphorus-31 (31P)-MRS and hydrogen (1H)-MEscher-GArwood Point RESolved Spectroscopy (MEGA-PRESS) in measuring 31P metabolites, γ-aminobutyric acid (GABA), and glutathione (GSH) using a 3T multi-nucleus magnetic resonance imaging (MRI) system.

METHODS

In total, 32 participants, who underwent two scanning sessions within three days, using two dimensional (2D)-chemical shift imaging (CSI)-31P-MRS and 1H-MEGA-PRESS sequences, were enrolled in the study. γ-aminobutyric acid and macromolecules (GABA+), glutamate and glutamine (Glx), GSH, and 12 31P metabolites were analyzed using the MATLAB-based tool Gannet and jMRUI software. Precision was assessed based on the coefficients of variation (CVs) and Bland-Altman plots.

RESULTS

The results revealed that potential of hydrogen (pH) and phosphocreatine (PCr) showed the greatest stability as evidenced by low CVs, suggesting reliable measurements across sessions. The adenosine triphosphates (ATPs) showed considerable stability. Conversely, metabolites, such as phosphomonoesters (PMEs) and phosphodiesters (PDEs), located to the left of PCr, showed reduced stability, while glycerophosphatidylcholine (GPTC) had the highest CV, indicating significant variability in clinical practice. Among the various brain regions, intermediate areas such as the temporal lobe and thalamus exhibited greater stability than peripheral regions such as the frontal and occipital lobes. Single-voxel MEGA-PRESS measurements showed that Glx and GABA+ had higher precision than GSH.

CONCLUSIONS

Both the 31P-MRS and 1H-MEGA-PRESS sequences showed high precision in measuring brain metabolites, but some metabolites showed higher stability than others. These results are crucial for exploring the clinical and research applications of these methods, and provide a solid foundation for subsequent investigations.