Normal lactate concentration range in the neonatal brain

Abstract

Objective: Lactate peaks are occasionally observed during in vivo magnetic resonance spectroscopy (MRS) scans of the neonatal brain, even in healthy patients. The purpose of this study was to investigate the normal range of neonatal brain lactate concentration, as a definitive normal range would be clinically valuable.

Methods: Using a clinical 3T scanner (echo/repetition times, 30/5000ms), single-voxel MRS data were obtained from the basal ganglia (BG) and centrum semiovale (CS) in 48 healthy neonates (postconceptional age (PCA), 30-43weeks), nine infants (age, 1-12months old), and 20 children (age, 4-15years). Lactate concentrations were calculated using an MRS signal quantification program, LCModel. Correlations between regional lactate concentration and PCA (neonates), or age (all subjects) were investigated.

Results: Absolute lactate concentrations of the BG and CS were as follows: neonates, 0.77mM (0-2.02) [median (range)] and 0.77 (0-1.42), respectively; infants, 0.38 (0-0.79) and 0.49 (0.17-1.17); and children, 0.17 (0-0.76) and 0.22 (0-0.80). Overall, subjects' lactate concentrations decreased significantly with age (Spearman: BG, n=61, ρ=-0.38, p=0.003; CS, n=68, ρ=-0.57, p<0.001). However, during the neonatal period no correlations were detected between lactate concentration in either region and PCA.

Conclusion: We determined normal ranges of neonatal lactate concentration, which may prove useful for diagnostic purposes. Further studies regarding changes in brain lactate concentration during development would help clarify the reasons for higher concentrations observed during the neonatal period, and contribute to improvements in diagnoses.

Keywords: Brain lactate concentration; Diagnostic index; MR spectroscopy; Neonates.