Big GABA: Edited MR spectroscopy at 24 research sites

Area of Science:

• Neuroimaging
• Biomedical Engineering
• Neuroscience

Background:

• Magnetic resonance spectroscopy (MRS) is unique for noninvasively measuring brain neurotransmitters like γ-aminobutyric acid (GABA).
• Advancements in hardware and pulse sequences (e.g., J-difference spectral editing) have increased GABA-edited MRS popularity.
• Variability in implementation across research sites hinders inter-study comparisons.

Purpose of the Study:

• To investigate factors influencing GABA-edited MRS measurement outcomes.
• To establish a framework for methodological standardization in GABA-edited MRS.
• To provide benchmarks for the MRS community.

Main Methods:

• An international consortium of 24 research sites acquired data from 272 healthy adults.
• Data were collected on scanners from three major MRI vendors using a standardized protocol in the medial parietal lobe.
• GABA-edited MRS utilized standard GABA+ and macromolecule-suppressed (MM-) editing sequences, analyzed with the Gannet pipeline.

Main Results:

• The coefficient of variation was 12% for GABA+ and 28% for MM-suppressed GABA measurements.
• Multilevel analysis showed participant differences explained most GABA+ variance (72%), with site (20%) and vendor (8%) differences being smaller.
• MM-suppressed GABA data variance was split equally between site (50%) and participant (50%) differences.

Conclusions:

• Standardized GABA-edited MRS protocols yield reliable GABA+ measurements with strong agreement.
• Increased variability in MM-suppressed GABA measurements is partly due to site-specific acquisition differences.
• The study provides a framework and benchmarks for future GABA-edited MRS standardization and research.