Edited MRS is sensitive to changes in lactate concentration during inspiratory hypoxia

Purpose: To demonstrate the application of Mescher-Garwood (MEGA) point-resolved spectroscopy sequence (PRESS) editing to the detection of lactate in the brain at 3T and to investigate changes in lactate concentration associated with inspiratory gas challenges. Materials and Methods: Edited lactate measurements were made in six healthy volunteers while the subjects breathed normoxic (21% O2), hypoxic (12% O2), and hyperoxic (40% O2) gas mixtures. Lactate concentration was quantified relative to the unsuppressed water signal from the same volume. Results: Lactate concentration was elevated in all subjects during hypoxia in a highly significant fashion (mean increase = 39%; P = 0.0003). There was no significant change seen in hyperoxia. Conclusion: MEGA-PRESS editing at 3T is sufficiently sensitive to detect lactate in the healthy brain with good signal-to-noise ratio (SNR), and can be used to investigate changes in cerebral metabolism arising during inspiratory gas challenges.