Whole-Brain Proton MR Spectroscopic Imaging in Parkinson's Disease

BACKGROUND AND PURPOSETo examine the distributions of proton magnetic resonance spectroscopy (MRS) observed metabolites in Parkinson's disease (PD) throughout the whole brain. METHODSTwelve PD patients and 18 age-matched controls were studied using neuropsychological testing, MRI and volumetric MR spectroscopic imaging. Average values of signal normalized metabolite values for N-acetyl-aspartate, total-creatine, and total-choline (NAA, total-Cre, total-Cho, respectively) and their ratios were calculated for gray matter (GM) and white matter (WM) in each lobar brain region. RESULTSAnalyses revealed altered metabolite values in PD subjects relative to controls within the GM of the temporal lobe (right: elevated Cre, P = .027; decreased NAA/Cre, P = .019; decreased Cho/Cre, P = .001 and left: decreased NAA/Cre; P = .001, decreased Cho/Cre, P = .007); the right occipital lobe (decreased NAA, P = .032 and NAA/Cre, P = .016); and the total cerebrum GM (decreased NAA/Cre, P = .029). No meaningful correlations were obtained between abnormal metabolite values and the neuropsychological measures. CONCLUSIONSPD is associated with widespread alterations of brain metabolite concentrations, with a primary finding of increased creatine. Higher creatine values in our PD sample may reflect greater neuronal energy expenditure early in the disease process that is compensatory. This is the first whole brain MRS study of PD that has examined metabolite changes across a large fraction of the brain volume, including the cortical mantle.