title: Effects of Alzheimer disease on fronto-parietal brain N-acetyl aspartate and myo-inositol using magnetic resonance spectroscopic imaging.
abstract: Previous magnetic resonance (MR) spectroscopy studies of Alzheimer disease (AD) reporting reduced N-acetyl aspartate (NAA) and increased myo-Inositol (mI) used single voxel techniques, which have limited ability to assess the regional distribution of the metabolite abnormalities. The objective of this study was to determine the regional distribution of NAA and mI alterations in AD by using MR spectroscopic imaging. Fourteen patients with AD and 22 cognitively normal elderly were studied using structural MR imaging and MR spectroscopic imaging. Changes of NAA, mI, and various metabolite ratios were measured in frontal and parietal lobe gray matter (GM) and white matter. This study found: (1) when compared with cognitively normal subjects, AD patients had increased mI and mI/creatine (Cr) ratios primarily in parietal lobe GM, whereas frontal lobe GM and white matter were spared; (2) in the same region where mI was increased, AD patients had also decreased NAA and NAA/Cr ratios, replicating previous findings; (3) however, increased mI or mI/Cr ratios did not correlate with decreased NAA or NAA/Cr ratios; and (4) using mI/Cr and NAA/Cr together improved sensitivity and specificity to AD from control as compared with NAA/Cr alone. In conclusion, decreased NAA and increased mI in AD are primarily localized in parietal lobe GM regions. However, the NAA and mI changes are not correlated with each other, suggesting that they represent different processes that might help staging of AD.
authors.affiliation: Department of Radiology, VA Medical Center, University of California, San Francisco, CA 94121, USA. zhupxia@itsa.ucsf.edu
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Zhu
authors.forename: Norbert
authors.initials: N
authors.lastname: Schuff
authors.forename: John
authors.initials: J
authors.lastname: Kornak
authors.forename: Brian
authors.initials: B
authors.lastname: Soher
authors.forename: Kristine
authors.initials: K
authors.lastname: Yaffe
authors.forename: Joel H
authors.initials: JH
authors.lastname: Kramer
authors.forename: Frank
authors.initials: F
authors.lastname: Ezekiel
authors.forename: Bruce L
authors.initials: BL
authors.lastname: Miller
authors.forename: William J
authors.initials: WJ
authors.lastname: Jagust
authors.forename: Michael W
authors.initials: MW
authors.lastname: Weiner
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000175:diagnosis / Q000503:physiopathology*; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D001931:Brain Mapping; D003401:Creatine / Q000378:metabolism; D005260:Female; D005625:Frontal Lobe / Q000503:physiopathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007294:Inositol / Q000378:metabolism*; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008609:Mental Status Schedule; D008875:Middle Aged; D009483:Neuropsychological Tests; D010296:Parietal Lobe / Q000503:physiopathology*; D012016:Reference Values; D013223:Statistics as Topic
chemical_list: D001224:Aspartic Acid; D007294:Inositol; C000179:N-acetylaspartate; D003401:Creatine