Magnetic Resonance Spectroscopy

BACKGROUND: Premature birth adversely affects infant and childhood developmental trajectories. Despite the absence of obvious neurological injury such as intraventricular hemorrhage or periventricular leukomalacia, school-age children born prematurely show microstructural differences in the brain compared with those born at term (Duerden, et. al., 2015). The Specific Test of Early Infant Motor Performance (STEP) is a novel infant motor skills test that has been introduced as an efficient developmental screening assessment for preterm infants that correlates with 12-month Bayley-III outcomes (Coker-Bolt et. al., 2016; Gower, Jenkins, Fraser, Ramakrishnan, Coker-Bolt, 2018). Neuroimaging with MRI provide a non-invasive means to quantify the neurodevelopmental status of infants through metabolic and structural measures. These measures may predict future neurodevelopmental outcomes such as functional motor and/or cognitive deficits. Further validation of the STEP via neuroimaging will therefore provide support that the STEP is assessing functions that are closely related to CNS structures. PURPOSE: To determine the relationship of the STEP to neuroimaging through Magnetic Resonance Spectroscopy (MRS) metabolite ratios and Fractional Anisotropy (FA). DESIGN AND METHODS: Prospective cohort study of 16 preterm infants were assessed using STEP outcome measures at 0-3 months corrected gestational age (GA), MRS and Diffusion Tensor Imaging (DTI) at term GA, and Bayley-III at 12 months. The STEP was administered by the same OTt, while a different, blinded OT administered the Bayley-III. Both therapists were blinded to neuroimaging results. Generalized linear models were created using MRS metabolite ratios or white matter (WM) tract FA value averages as covariates to predict STEP. Generalized linear models were created using the metabolite ratios or average FA values and STEP score at term or 3 months to predict Bayley gross motor (GM) and cognitive scores at 12 months. RESULTS: (n=16); 2 infants with neonatal blood-culture proven sepsis, 2 infants with chorioamnionitis and periventricular leukomalacia, 2 infants had intraventricular hemorrhage, 1 infant with large cerebellar hemorrhage. Ratios of N-acetyl aspartate to creatine (NAA) in both frontal WMand basal ganglia (BG) significantly contribute to a model predicting STEP scores at both term and 3 months. NAA and myoinositol ratios in the BG both significantly predict Bayley cognitive scores at 12 months. Additiona