DEVELOPMENTAL-CHANGES OF PHOSPHORUS METABOLITE CONCENTRATIONS IN THE HUMAN BRAIN - A P-31 MAGNETIC-RESONANCE SPECTROSCOPY STUDY IN-VIVO

Phosphorus magnetic resonance spectroscopy is a noninvasive method to investigate brain metabolism in vivo. ATP generally serves as an inter nal concentration standard for the quantification of the various phosp horus metabolites, because the ATP concentration in mammalian brains i s assumed to be age independent. This presumption is based on observat ions made in the biochemical analysis of the developing rat brain. In the present study, metabolite concentrations were assessed with an ext ernal concentration standard. Each brain spectrum was quantified using a calibration spectrum that was acquired from a phantom after the in vivo brain measurement. Fully relaxed localized brain spectra were obt ained from 16 neonates (2-28 d), 17 infants (6-20 mo), and 28 adults ( 22-58 y). The metabolite concentrations (in mmol/L) changed from neona tes to adults: phosphomonoester from 4.5 to 3.5, inorganic phosphate f rom 0.6 to 1.0, phosphodiester from 3.2 to 11.7, phosphocreatine from 1.4 to 3.4, and ATP from 1.6 to 2.9. We conclude that 1) the ATP conce ntration in the human brain almost doubles between neonates and adults , and 2) ATP may not be used as an age-independent internal concentrat ion standard.