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Measurement of brain lactate during visual stimulation using a long TE semi‐LASER sequence at 7 T
Author(s) -
Fernandes Carolina C.,
Lanz Bernard,
Chen Chen,
Morris Peter G.
Publication year - 2020
Publication title -
nmr in biomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.278
H-Index - 114
eISSN - 1099-1492
pISSN - 0952-3480
DOI - 10.1002/nbm.4223
Subject(s) - glutamate receptor , stimulation , visual cortex , chemistry , in vivo , nuclear magnetic resonance , neuroscience , biology , biochemistry , physics , receptor , microbiology and biotechnology
Estimation of metabolic changes during neuronal activation represents a challenge for in vivo MRS, especially for metabolites with low concentration and signal overlap, such as lactate. In this work, we aimed to evaluate the feasibility of detecting lactate during brain activation using a long T E (144 ms) semi‐LASER sequence at 7 T.1 H spectra were acquired on healthy volunteers ( N = 6 ) during a paradigm with 15 min of visual stimulation. Outer‐volume signals were further attenuated by the use of saturation slabs, and macromolecular signals in the vicinity of the inverted lactate peak were individually fitted with simulated Lorentzian peaks. All spectra were free of artefacts and highly reproducible across subjects. Lactate was accurately quantified with an average Cramér‐Rao lower bound of 8%. Statistically significant ( P < 0 . 05 , one‐tailed t ‐test) increases in lactate ( ∼ 10%) and glutamate ( ∼ 3%) levels during stimulation were detected in the visual cortex. Lactate and glutamate changes were consistent with previous measurements. We demonstrated that quantification of a clear and non‐contaminated lactate peak obtained with a long TE sequence has the potential of improving the accuracy of functional MRS studies targeting non‐oxidative reaction pathways.