A Guide to the Metabolic Pathways and Function of Metabolites Observed in Human Brain 1H Magnetic Resonance Spectra

The current knowledge of the normal biochemistry of compounds that give rise to resonances in human brain proton magnetic resonance spectra measureable at readily available field strengths (i.e. a parts per thousand currency sign3 T) is reviewed. Molecules covered include myo- and scyllo-inositol, glycerophospho- and phospho-choline and choline, creatine and phosphocreatine, N-acetylaspartate, N-acetylaspartylglutamate, glutamate, glutamine, gamma-aminobutyrate, glucose, glutathione and lactate. The factors which influence changes in the levels of these compounds are discussed. As most proton resonances in the brain at low field are derived from a combination of moieties whose biochemistry is complex and interrelated, an understanding of the mechanisms underlying why these species change is crucial to meaningful interpretation of human brain spectra.