134 - Extrauterine Somatic Growth Restriction Affects Volumetric Brain Growth in Preterm Infants

Premature infants are at risk for growth failure during the extra-uterine period, particularly in the third trimester which is a critical window for exponential brain growth and maturation. Extra-uterine somatic growth restriction (EUGR) has been associated with neurodevelopmental deficits, but its direct relationship with concurrent brain growth is not clearly understood.

Objective:

To investigate the relationship of EUGR with total and regional brain volumetric growth in preterm infants.

Design/Methods:

We prospectively enrolled premature infants born at gestational age (GA) ≤35 weeks and acquired longitudinal magnetic resonance imaging (MRI) of the brain every 4-6 weeks until term equivalent age (TEA). 3D CUBE images were segmented using ITK-SNAP to quantify total and regional (cortical gray matter, subcortical gray matter, white matter, and cerebellum) brain volumes (Figure 1). Somatic growth parameters (body weight, length, and head circumference; and respective z-scores) at the time of each MRI were obtained by chart review. Infants with body weight z-scores less than -1 at TEA were classified as EUGR (Figure 2a). Parametric tests were performed to investigate for relationship of brain volumes with somatic growth parameters, and differences between infants with and without EUGR.

Results:

47 infants born at a mean GA of 29.9 ±3.6 weeks underwent serial MRI with final MRI at TEA (mean postmenstrual age of 40.5±1.6 weeks.) Somatic and brain measurements longitudinally increased during the extrauterine third trimester (Table 1).  Brain volumes positively correlated with somatic measures, demonstrating strongest correlation with head circumference (Pearson Rho 0.8-0.9, P< 0.01); this association strengthened when approaching TEA. Infants with EUGR had smaller cerebellar (19.5± 4.4 vs. 22.7 ± 3.5 cc; P=.018) and subcortical gray matter (22.1 ±2.8 vs. 24.7 ± 2.5 cc, P=.007) volumes, compared to those without EUGR at TEA (Figure 2b). Total brain volume and white matter volumes trended lower (P=0.55) in infants with EUGR (Figure 2b).

Conclusion(s): Head circumference (followed by >body weight > length) demonstrate stronger correlation with brain volume growth, emphasizing limitations in using weight for growth assessment, particularly in respect to brain development. Association of smaller cerebellar and subcortical gray matter volume with EUGR indicates its relevance as a biomarker of neurodevelopmental outcomes. Investigations into links between postnatal nutrient intake, EUGR and regional brain volumes is currently underway.