title: Sensitivity of single-voxel 1H-MRS in investigating the metabolism of the activated human visual cortex at 7 T.
abstract: Proton magnetic resonance spectroscopy (1H-MRS) has been used in a number of studies to noninvasively assess the temporal changes of lactate in the activated human brain. However, the results have not been consistent. The aim of the present study was to test the sensitivity of 1H-MRS during functional experiments at the highest magnetic field currently available for human studies (7 T). Stability and reproducibility of the measurements were evaluated from LCModel analysis of time series of spectra measured during a visual stimulation paradigm and by examination of the difference between spectra obtained at rest and during activation. The sensitivity threshold to detect concentration changes was 0.2 micromol/g for most of the quantified metabolites. The possible variations of metabolite concentrations during visual stimulation were within the same range (+/-0.2 micromol/g). In addition, the influence of a small line-narrowing effect due to the blood oxygenation level-dependent (BOLD) T2* changes on the estimated concentrations was simulated. Quantification of metabolites was, in general, not affected beyond 1% by line-width changes within 0.5 Hz.
authors: Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, MN 55455, USA. mangia@cmrr.umn.edu
authors: Silvia
authors: S
authors: Mangia
authors: Ivan
authors: I
authors: Tkác
authors: Rolf
authors: R
authors: Gruetter
authors: Pierre-Francois
authors: PF
authors: Van De Moortele
authors: Federico
authors: F
authors: Giove
authors: Bruno
authors: B
authors: Maraviglia
authors: Kâmil
authors: K
authors: Uğurbil