O50. Regional differences in absolute metabolite level couplings in a longitudinal study of children

Introduction Magnetic resonance imaging (MRI) provides information about the structure, function and biochemistry of the developing brain. Magnetic resonance spectroscopy (1H-MRS) non-invasively quantifies metabolites that play important roles in neurodevelopment. Throughout childhood the brain develops biochemically, and different metabolites may develop in tandem depending on the brain region. Examining the regional intercorrelations between metabolites such as NAA, creatine, choline and glutamate provides insight in the role of individual and coupled biochemicals in the developing brain. Understanding how metabolites are inter-related may provide insight into healthy brain growth, and create norms to aid in identifying pathology and abnormal development. Here we identify couplings of typically measured metabolites – NAA, creatine, glutamate, choline – in a representative pediatric population in South Africa. Materials and methods A high-resolution T1-weighted acquisition and single voxel 1H-MRS in gray matter, white matter and basal ganglia (BG) were performed on a Siemens 3T Allegra Head Scanner (Siemens, Erlangen, Germany) in Cape Town, South Africa. MRS used a real-time motion and B0 corrected PRESS (TR/TE 2000/30 ms, 64 averages, 2:16 min). Twenty-nine 5-year-old, forty-nine 7-year-old, and twenty-nine 9-year-old typically developing children were scanned. Results Gray matter: We found significant couplings between NAA-creatine (slope = 0.68, p  0.0001), choline-creatine (slope = 0.12, p  = 0.0002), NAA-glutamate (slope = 0.26, p  0.0001) and creatine-glutamate (slope = 1.2, p  0.0001). White matter: We found significant couplings between NAA-creatine (slope = 0.86; p  0.0001), NAA-glutamate (slope = 0.20; p  = 0.004) and creatine-glutamate (slope = 1.3; p  = 0.0001). BG. No statistically significant associations. Conclusion Our results reveal regionally dependent metabolite couplings in the developing brain. The significant couplings in gray and white matter, in contrast to the BG, suggests that development during this period is more dynamic in white and gray matter compared to subcortical structures which develop earlier.