Comparison of the repeatability of GABA-edited magnetic resonance spectroscopy with and without macromolecule suppression.
OBJECTIVE
The inhibitory neurotransmitter γ-aminobutyric acid (GABA) can be measured in vivo using edited magnetic resonance spectroscopy (MRS), but quantification suffers from contamination by macromolecules (MM). It is possible to suppress this contamination using symmetric editing, but this procedure potentially compromises reliability of the GABA measurement. The aim of this study was to compare the repeatability of GABA-edited MRS with and without MM suppression.


METHODS
GABA' (non-MM contaminated) and GABA'+MM (MM-contaminated) concentration was measured in the occipital lobe (OCC) and anterior cingulate (AC) using symmetric and standard editing (n = 15). Each method was performed twice in each region.


RESULTS
Within-participant coefficients of variation for each technique were 4.0% (GABA'+MM) and 8.6% (GABA') in the OCC and 14.8% (GABA'+MM) and 12.6% (GABA') in the AC. Intraclass correlation coefficients were better for the suppression method than standard editing in both the OCC (0.72 versus 0.67) and AC (0.41 versus 0.16). These findings were replicated in the OCC of a second cohort (n = 15).


CONCLUSIONS
Symmetric suppression is shown to be comparable in repeatability to standard GABA-editing. Measuring a purer quantification of GABA becomes increasingly important as more research is conducted on links between GABA concentration, pathology and healthy behavior.
CUBRIC, School of Psychology, Cardiff University, Cardiff, United Kingdom.
Mark
http://orcid.org/0000-0002-0349-3782
M
Mikkelsen
CUBRIC, School of Psychology, Cardiff University, Cardiff, United Kingdom.
Krish D
KD
Singh
CUBRIC, School of Psychology, Cardiff University, Cardiff, United Kingdom.
Petroc
P
Sumner
CUBRIC, School of Psychology, Cardiff University, Cardiff, United Kingdom.
C John
CJ
Evans
D000328:Adult; D001921:Brain / Q000378:metabolism; D001923:Brain Chemistry; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods* / Q000592:standards*; D008297:Male; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012815:Signal Processing, Computer-Assisted; D055815:Young Adult; D005680:gamma-Aminobutyric Acid / Q000737:chemistry / Q000378:metabolism*
D005680:gamma-Aminobutyric Acid
GABA; MRS; macromolecules; repeatability; symmetric suppression