Excessive exposure to manganese (Mn) results in Mn deposition in the brain causing adverse neurological effects. Sick infants requiring parenteral nutrition (PN) may be at increased risk of Mn neurotoxicity because neonatal PN solutions contain high concentrations of Mn. This proposal will investigate brain deposition of Mn, a paramagnetic element, by magnetic resonance (MR) imaging in preterm and term neonates receiving Mn-supplemented PN and gestational age-matched control infants. The goals of this project are to identify neonatal populations that are at increased risk of excessive brain Mn deposition based on their gestational age, iron status, hepatic function and dietary Mn intake, and to make evidence-based recommendations for appropriate Mn supplementation and monitoring of infants receiving PN.