Simultaneous Measurement of the BOLD Effect and Metabolic Changes in Response to Visual Stimulation Using the MEGA-PRESS Sequence at 3 T.

Autor:	Dwyer GE; Department of Biological and Medical Psychology, University of Bergen, Bergen, Norway.; NORMENT Centre of Excellence, Haukeland University Hospital, Bergen, Norway., Craven AR; Department of Biological and Medical Psychology, University of Bergen, Bergen, Norway.; NORMENT Centre of Excellence, Haukeland University Hospital, Bergen, Norway.; Department of Clinical Engineering, Haukeland University Hospital, Bergen, Norway., Bereśniewicz J; Department of Biological and Medical Psychology, University of Bergen, Bergen, Norway.; NORMENT Centre of Excellence, Haukeland University Hospital, Bergen, Norway., Kazimierczak K; Department of Biological and Medical Psychology, University of Bergen, Bergen, Norway.; Mohn Medical Imaging and Visualization Centre, Haukeland University Hospital, University of Bergen, Bergen, Norway., Ersland L; Department of Biological and Medical Psychology, University of Bergen, Bergen, Norway.; NORMENT Centre of Excellence, Haukeland University Hospital, Bergen, Norway.; Department of Clinical Engineering, Haukeland University Hospital, Bergen, Norway., Hugdahl K; Department of Biological and Medical Psychology, University of Bergen, Bergen, Norway.; Department of Radiology, Haukeland University Hospital, Bergen, Norway.; Division of Psychiatry, Haukeland University Hospital, Bergen, Norway., Grüner R; NORMENT Centre of Excellence, Haukeland University Hospital, Bergen, Norway.; Mohn Medical Imaging and Visualization Centre, Haukeland University Hospital, University of Bergen, Bergen, Norway.; Department of Radiology, Haukeland University Hospital, Bergen, Norway.; Department of Physics and Technology, University of Bergen, Bergen, Norway.
Jazyk:	angličtina
Zdroj:	Frontiers in human neuroscience [Front Hum Neurosci] 2021 Mar 24; Vol. 15, pp. 644079. Date of Electronic Publication: 2021 Mar 24 (Print Publication: 2021).
DOI:	10.3389/fnhum.2021.644079
Abstrakt:	The blood oxygen level dependent (BOLD) effect that provides the contrast in functional magnetic resonance imaging (fMRI) has been demonstrated to affect the linewidth of spectral peaks as measured with magnetic resonance spectroscopy (MRS) and through this, may be used as an indirect measure of cerebral blood flow related to neural activity. By acquiring MR-spectra interleaved with frames without water suppression, it may be possible to image the BOLD effect and associated metabolic changes simultaneously through changes in the linewidth of the unsuppressed water peak. The purpose of this study was to implement this approach with the MEGA-PRESS sequence, widely considered to be the standard sequence for quantitative measurement of GABA at field strengths of 3 T and lower, to observe how changes in both glutamate (measured as Glx) and GABA levels may relate to changes due to the BOLD effect. MR-spectra and fMRI were acquired from the occipital cortex (OCC) of 20 healthy participants whilst undergoing intrascanner visual stimulation in the form of a red and black radial checkerboard, alternating at 8 Hz, in 90 s blocks comprising 30 s of visual stimulation followed by 60 s of rest. Results show very strong agreement between the changes in the linewidth of the unsuppressed water signal and the canonical haemodynamic response function as well as a strong, negative, but not statistically significant, correlation with the Glx signal as measured from the OFF spectra in MEGA-PRESS pairs. Findings from this experiment suggest that the unsuppressed water signal provides a reliable measure of the BOLD effect and that correlations with associated changes in GABA and Glx levels may also be measured. However, discrepancies between metabolite levels as measured from the difference and OFF spectra raise questions regarding the reliability of the respective methods. Competing Interests: AC, LE, KH, and RG have shares in the company NordicNeuroLab A/S which produces add-on equipment for MRI examinations that were used in this study. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. (Copyright © 2021 Dwyer, Craven, Bereśniewicz, Kazimierczak, Ersland, Hugdahl and Grüner.)
Databáze:	MEDLINE
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