title: Longitudinal absolute metabolite quantification of white and gray matter regions in healthy controls using proton MR spectroscopic imaging.
abstract: The purpose of this study was to evaluate quality parameters, metabolite concentrations and concentration ratios, and to investigate the reproducibility of quantitative proton magnetic resonance spectroscopic imaging ((1)H-MRSI) of selected white and gray matter regions of healthy adults. 2D-quantitative short-TE (1)H-MRSI spectra were obtained at 1.5T from the healthy human brain. Subjects (n = 12) were scanned twice with an interval of six months. Absolute metabolite concentrations were obtained based on coil loading, taking into account differences in sensitivity of the phased-array head coil. Spectral quality parameters, absolute metabolite concentrations, concentration ratios, and their reproducibility were determined and compared between time-points using a repeated measures general linear model. The quality of the spectra of selected brain areas was good, as determined by a mean spectral linewidth between 4.8 and 7.3 Hz (depending on the region). No significant differences between the two time-points were observed for spectral quality, concentrations, or concentration ratios. The mean intrasubject coefficient of variation (CoV) varied between 4.0 and 8.5% for total N-acetylaspartate, 7.2 and 10.8% for total creatine, 5.9 and 9.8% for myo-inositol, and 8.0 and 13.3% for choline, and remained below 20% for glutamate. CoV was generally lower when concentration ratios were considered. The study shows that longitudinal quantitative short-TE (1)H-MRSI generates reproducible absolute metabolite concentrations in healthy human white and gray matter. This may serve as a background for longitudinal clinical studies in adult patients.
authors.affiliation: Department of Radiology and Nuclear Medicine, Neuroscience Campus Amsterdam and VU University Medical Center, Amsterdam, the Netherlands; Department of Anatomy and Neurosciences, Neuroscience Campus Amsterdam and VU University Medical Center, Amsterdam, the Netherlands.
authors.forename: Oliver T
authors.initials: OT
authors.lastname: Wiebenga
authors.forename: Antoine M
authors.initials: AM
authors.lastname: Klauser
authors.forename: Gijsbert J A
authors.initials: GJ
authors.lastname: Nagtegaal
authors.forename: Menno M
authors.initials: MM
authors.lastname: Schoonheim
authors.forename: Frederik
authors.initials: F
authors.lastname: Barkhof
authors.forename: Jeroen J G
authors.initials: JJ
authors.lastname: Geurts
authors.forename: Petra J W
authors.initials: PJ
authors.lastname: Pouwels
mesh_terms: D000328:Adult; D001921:Brain / Q000033:anatomy & histology* / Q000378:metabolism*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D055442:Metabolome; D011522:Protons; D059629:Signal-To-Noise Ratio
chemical_list: D011522:Protons
keywords: MRSI; chemical shift imaging; gray matter; healthy controls; metabolites; reproducibility; spectroscopy; white matter