Reproducibility of GABA and Glx measurements in the midbrain and basal ganglia using MEGA-PRESS

Motivation: Reproducibility is critical in longitudinal studies to monitor subtle alterations of GABA and Glx concentration in neurodegenerative disorders. Goal(s): To evaluate the reproducibility of GABA and Glx measurements of the midbrain and basal ganglia regions in healthy subjects. Approach: The MEGA-PRESS sequence was scanned twice with a two-week gap for each subject to obtain the GABA and Glx level in the left basal ganglia and bilateral midbrain. The reproducibility was evaluated. Results: We observed good agreement between two scans for the GABA and Glx quantification based on the Bland-Altman analysis. Impact: The reproducibility analysis of GABA and Glx measurements in the basal ganglia and midbrain regions are needed for the follow-up studies. The preliminary results informed that applying 1H-MRS to investigate the progression of GABA and Glx levels is applicable.