title: Spectral-editing measurements of GABA in the human brain with and without macromolecule suppression.
abstract: OBJECTIVE
  The conventional spectral-editing experiment used to measure GABA in the human brain also contains a contribution from macromolecules (MM), and the combined GABA plus MM signal is often referred to as "GABA+". More recently, methods have been developed to estimate GABA free from MM contamination. In this study, the relationship between GABA acquired with MM suppression and conventional GABA+ measurements was examined.
  
  
  METHODS
  GABA-edited MEGA-PRESS experiments with and without MM suppression were performed in the sensorimotor and occipital cortex of 12 healthy subjects at 3 Tesla. The correlation between GABA+ and MM-suppressed GABA measures was then determined.
  
  
  RESULTS
  Across all data, a significant correlation between GABA+ and MM-suppressed GABA was found (r = 0.48; P = 0.02). Regionally, the sensorimotor voxel showed a trend toward a correlation of r = 0.53, P = 0.07 and the occipital voxel did not show a correlation, r = 0.058, P = 0.9.
  
  
  CONCLUSIONS
  GABA+ and MM-suppressed GABA are moderately correlated, but statistical power to reveal this relationship may vary regionally. The MM signal, while often assumed to be functionally irrelevant, appears to show inter-individual and inter-regional variance that impacts the correlation of GABA+ and MM-suppressed GABA.
authors.affiliation: Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University, Baltimore, Maryland, USA.|F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA.
authors.forename: Ashley D
authors.initials: AD
authors.lastname: Harris
authors.affiliation: Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University, Baltimore, Maryland, USA.|F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA.
authors.forename: Nicolaas A J
authors.initials: NA
authors.lastname: Puts
authors.affiliation: Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University, Baltimore, Maryland, USA.|F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA.
authors.forename: Peter B
authors.initials: PB
authors.lastname: Barker
authors.affiliation: Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University, Baltimore, Maryland, USA.|F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA.
authors.forename: Richard A E
authors.initials: RA
authors.lastname: Edden
mesh_terms: D000328:Adult; D000465:Algorithms; D002540:Cerebral Cortex / Q000378:metabolism*; D006801:Humans; D046911:Macromolecular Substances / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D057054:Molecular Imaging / Q000379:methods; D018377:Neurotransmitter Agents / Q000378:metabolism; D010363:Pattern Recognition, Automated / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013382:Subtraction Technique; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: D046911:Macromolecular Substances; D018377:Neurotransmitter Agents; D005680:gamma-Aminobutyric Acid
keywords: GABA; brain; edited MRS; macromolecules GABA+