Basal ganglia metabolite concentrations in idiopathic Parkinson's disease and multiple system atrophy measured by proton magnetic resonance spectroscopy

Six patients with idiopathic Parkinson's disease (IPD), six with clinically probable multiple system atrophy and six control subjects underwent quanti tative proton magnetic resonance spectroscopy (MRS). The concentrations of the three major metabolites, N-acetylaspartate (NAA), creatine and choline, were quantified in the lentiform nucleus using tissue water content as an internal concentration reference. Glutamate was assessed as the (glutamate + glutamine)/creatine peak area ratio (Glx/Cre). In the control subjects th e mean (+/- SD) concentrations of the three metabolites were 15.2 +/- 2.9 m u mol/ g wet weight for NAA, 12.0 +/- 1.4 for creatine and 2.4 +/- 0.3 for choline. The Glx/Cre ratio was 1.28 +/- 0.32. The only significant differen ce in any metabolite concentration was in the lentiform nucleus of patients with IPD compared with controls, with an increase in choline which lead to a significant reduction in the NAA/choline ratio. The relevance of this fi nding is uncertain. The results of the present pilot study, combined with t he conflicting findings from previous work, suggest that further, much larg er, studies are required to evaluate the diagnostic capability of proton MR S.