Cerebral metabolic rate for glucose during the first six months of life: An FDG positron emission tomography study

Abstract

Aim - To measure the local cerebral metabolic rate for glucose (LCMRGlc) in neonatal brains during maturation using positron emission tomography (PET) and 2-[18F]fluoro-2-deoxy-D-glucose (FDG). Methods - Twenty infants were studied using PET during the neonatal period. The postcoiiceptional age ranged from 32-7 to 60-3 weeks. All infants had normal neurodevelopment and were normoglycaemic. The development of the infants was carefully evaluated (follow up 12-36 months) clinically, and by using a method based on Gesell Amatruda's developmental diagnosis. LCMRGlc was quantitated using PET derived from FDG kinetics and calculated in the whole brain and for regional brain structures. Results-LCMRGlc for various cortical brain regions and the basal ganglia was low at birth (from 4 to 16 μmol/100 g/minute). In infants 2 months of age and younger LCMRGlc was highest in the sensorimotor cortex, thalamus, and brain stem. By 5 months, LCMRGlc had increased in the frontal, parietal, temporal, occipital and cerebellar cortical regions. In general, the whole brain LCMRGlc correlated with postconceptional age (r=0-90; P<0-001). The change in the glucose metabolic pattern observed in the neonatal brain reflects the functional maturation of these brain regions. Conclusion - These findings show that LCMRGlc in infants increases with maturation. Accordingly, when LCMRGlc is measured during infancy, the postconceptional age has to be taken into account when interpretating the results.