Evolution of pattern of injury and quantitative MRI on days 1 and 3 in term newborns with hypoxic-ischemic encephalopathy

BACKGROUND: Brain injury in term neonatal hypoxic ischemic encephalopathy (HIE) emerges on magnetic resonance imaging (MRI) by day 3. This study aimed to address the relationship of MRI, diffusion tensor imaging (DTI), and MR spectroscopic imaging (MRSI) findings on days 1 and 3 in a prospective cohort of term newborns with HIE. METHODS: A total of 24 term newborns with HIE were prospectively studied with MRI on days 1 and 3; 19 were imaged with DTI and MRSI on days 1 and 3. MRI was assessed using validated scores. The relationship between MRI, DTI, and MRSI values on days 1 and 3 was determined using linear regression for repeated measures. RESULTS: Conventional MRI showed a complex variation of findings from day 1 to 3. In gray matter, mean diffusivity (D-av) and metabolite ratios measured on day 1 were predictive of values on day 3 (all P <= 0.04). In white matter, D-av, fractional anisotropy (FA), and N-acetylaspartate (NAA)/choline on days 1 and 3 were strongly related (all P <= 0.003). Hypothermia appeared to attenuate the severity and progression of brain injury in the six treated newborns. CONCLUSION: In term newborns with HIE, quantitative MR values on days 1 and 3 are strongly associated, providing an objective measure of injury before qualitative images.