title: Using proton magnetic resonance spectroscopy to identify mild cognitive impairment.
abstract: BACKGROUND
  Single-volume proton magnetic resonance spectroscopy (1H MRS) has considerable diagnostic potential for Alzheimer's disease (AD). This study investigated 1H MRS in specific regions of the brain, the posterior cingulate gyri (PCG) and the hippocampus, in patients with AD, amnestic mild cognitive impairment (aMCI), and in normal control subjects.
  
  
  METHODS
  1H MRS analysis was carried out on 47 patients with AD, 32 patients with aMCI and 56 normal control subjects (NC group). Volumes of the PCG and hippocampus were assessed, and the metabolic signals of N-acetylaspartate (NAA), choline compounds (Cho), myo-inositol (mI), and creatine (Cr) were quantified.
  
  
  RESULTS
  In the PCG, differences between the test groups were found in NAA/Cr, Cho/Cr, mI/Cr and NAA/mI ratios. Group differences were also found in mI/Cr and NAA/mI ratios in the left hippocampus, and in mI/Cr and NAA/mI ratios in the right hippocampus. NAA/Cr ratios increased in the PCG between AD and aMCI patients, and between aMCI and NC patients. Conversely, mI/Cr ratios in the PCG and left hippocampus decreased across AD, aMCI, and NC subjects. In discriminate and ROC (Receiver Operating Characteristic) analyses, a NAA/Cr ratio of ≤ 1.50 in the PCG indicated optimal potential for discriminating between aMCI patients and normal control subjects. Discriminating potential was also found to be high for a NAA/mI ratio in the PCG of ≤ 2.72. Despite significant differences between NC and aMCI patients in the mI/Cr ratio in the PCG and in the NAA/mI ratio in the left hippocampus, their sensitivity and specificity were all lower than 75%.
  
  
  CONCLUSIONS
  Proton MRS of the PCG using the NAA/Cr ratio as a metabolic marker indicates considerable potential for distinguishing between aMCI and NC subjects.
authors.affiliation: Department of Geriatric Psychiatry, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine and Alzheimer's Disease and Related Disorders Center, Shanghai Jiaotong University, Shanghai, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Wang
authors.forename: Shifu
authors.initials: S
authors.lastname: Xiao
authors.forename: Xia
authors.initials: X
authors.lastname: Li
authors.forename: Bei
authors.initials: B
authors.lastname: Ding
authors.forename: Huawei
authors.initials: H
authors.lastname: Ling
authors.forename: Kemin
authors.initials: K
authors.lastname: Chen
authors.forename: Yiru
authors.initials: Y
authors.lastname: Fang
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D001921:Brain / Q000378:metabolism / Q000473:pathology; D016022:Case-Control Studies; D002794:Choline / Q000378:metabolism; D060825:Cognitive Dysfunction / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D003401:Creatine / Q000378:metabolism; D005260:Female; D006179:Gyrus Cinguli / Q000378:metabolism / Q000473:pathology; D006624:Hippocampus / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007294:Inositol / Q000378:metabolism; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D059906:Neuroimaging
chemical_list: D001224:Aspartic Acid; D007294:Inositol; C000179:N-acetylaspartate; D003401:Creatine; D002794:Choline