  Over the past two decades, magnetic resonance spectroscopy with two-shot
difference editing has been widely employed to characterize altered levels of
GABA, the primary inhibitory neurotransmitter in the brain, in various
neuropsychiatric disorders. This conventional technique detects the GABA H4
resonance, making it unsuitable for investigating GABA metabolism. It also
suffers from subtraction artifacts, signal loss, and significant contamination
by macromolecules. Here, we introduce a single-shot method for detecting GABA
H2, effectively overcoming these difficulties. Since GABA turnover initiates at
its protonated C2 and unprotonated C1 positions, we demonstrate, for the first
time, noninvasive real-time monitoring of GABA metabolism in the human brain,
utilizing GABA H2 as a highly sensitive reporter for GABA C2. This new method
not only enhances the quantitative measurement of GABA levels but also opens up
a new avenue to probe the metabolic processes underlying alterations in GABA
levels in patients.
