Physiological and pathological clinical conditions and light scattering in brain

MRI of preterm infants at term commonly reveals subtle brain lesions such as diffuse white matter injury, which are linked with later cognitive impairments. The timing and mechanism of such injury remains unclear. The reduced scattering coefficient of near-infrared light (μ(s)’) has been shown to correlate linearly with gestational age in neonates. To identify clinical variables associated with brain μ(s)’, 60 preterm and full-term infants were studied within 7 days of birth. Dependence of μ(s)’ obtained from the frontal head on clinical variables was assessed. In the univariate analysis, smaller μ(s)’ was associated with antenatal glucocorticoid, emergency Caesarean section, requirement for mechanical ventilation, smaller gestational age, smaller body sizes, low 1- and 5-minute Apgar scores, higher cord blood pH and PO(2), and higher blood HCO(3)(−) at the time of study. Multivariate analysis revealed that smaller gestational age, requirement for mechanical ventilation, and higher HCO(3)(−) at the time of study were correlated with smaller μ(s)’. Brain μ(s)’ depended on variables associated with physiological maturation and pathological conditions of the brain. Further longitudinal studies may help identify pathological events and clinical conditions responsible for subtle brain injury and subsequent cognitive impairments following preterm birth.