Physiological and pathological clinical conditions and light scattering in brain

Abstract

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 (μs’) has been shown to correlate linearly with gestational age in neonates. To identify clinical variables associated with brain μs’, 60 preterm and full-term infants were studied within 7 days of birth. Dependence of μs’ obtained from the frontal head on clinical variables was assessed. In the univariate analysis, smaller μs’ 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 PO2, and higher blood HCO3− at the time of study. Multivariate analysis revealed that smaller gestational age, requirement for mechanical ventilation, and higher HCO3− at the time of study were correlated with smaller μs’. Brain μs’ 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.

Foetal growth, birth transition, enteral nutrition and brain light scattering

“…When preterm infants were studied shortly after birth, μ S ’ values obtained from the forehead showed a positive linear correlation with gestational age 16 . Our study in preterm and term infants further confirmed that μ S ’ values obtained shortly after birth were associated with variables, such as antenatal glucocorticoid, emergency delivery, gestational age, body size, Apgar scores, requirement for mechanical ventilation and blood gas data at birth, suggesting the possibility that μ S ’ might reflect subtle structural changes in the brain associated with antenatal growth, peripartum stress and birth transition 17 . However, little is known regarding the relationship between μ S ’ values obtained from the head of newborn infants and their downstream clinical outcomes.…”

“…Our previous study confirmed that μ S ’ values obtained from the foreheads of preterm and term infants assessed shortly after birth were dependent on body size and Apgar scores, as well as on gestational age. These findings suggest the possible utility of μ S ’ values as a non-invasive marker to evaluate subtle differences in the brain subsequent to foetal maturation, antenatal stress and birth transition 17 . Our current study further verified that the μ S ’ value obtained at term equivalent period is associated with both clinical variables at birth and those related to the nutritional status of the infant after birth.…”

Investigation of Confounding Factors in Measuring Tissue Saturation with NIRS Spatially Resolved Spectroscopy

“…This demonstrates the importance of having a subject-appropriate estimation of wavelength dependence of scattering. It has been shown that scattering properties change with age and pathology [ 6 – 8 ]; more investigations of the scattering dependence on wavelength and its behaviour during pathology are needed.…”

“…Highton et al measured a value of h = 0.00085 mm −1 nm −1 in adults with traumatic brain injury [ 5 ]. Kurata et al measured optical properties of the neonatal brain [ 6 ], a value of h = 0.00048 mm −1 nm −1 was calculated from the data for term infants using the method described by Matcher et al [ 4 ]. Approach 3, “Distance”: The number and combination of source-detector separations was adjusted.…”

Working memory mediates the effects of gestational age at birth on expressive language development in children.

“…As an alternative explanation, neuroimaging studies have shown that preterm infants have subtle brain lesions such as diffuse white matter abnormalities, which are linked with both later cognitive and language impairments (e.g., Kurata et al, 2016;Woodward, Clark, Bora & Inder, 2012). Even if these abnormalities are most common in very preterm children (< 32 gestational weeks), it could be the case that memory and expressive language difficulties co-exist due to common underlying neural pathology.…”