Abstract
ObjectivesThe severity of neurocognitive impairment increases with prematurity. However, its mechanisms remain poorly understood. Our aim was firstly to identify multiparametric magnetic resonance imaging (MRI) markers that differ according to the degree of prematurity, and secondly to evaluate the impact of clinical complications on these markers.Materials and MethodsWe prospectively enrolled preterm infants who were divided into two groups according to their degree of prematurity: extremely preterm (<28 weeks’ gestational age) and very preterm (28–32 weeks’ gestational age). They underwent a multiparametric brain MRI scan at term-equivalent age including morphological, diffusion tensor and arterial spin labeling (ASL) perfusion sequences. We quantified overall and regional volumes, diffusion parameters, and cerebral blood flow (CBF). We then compared the parameters for the two groups. We also assessed the effects of clinical data and potential MRI morphological abnormalities on those parameters.ResultsThirty-four preterm infants were included. Extremely preterm infants (n = 13) had significantly higher frontal relative volumes (p = 0.04), frontal GM relative volumes (p = 0.03), and regional CBF than very preterm infants, but they had lower brainstem and insular relative volumes (respectively p = 0.008 and 0.04). Preterm infants with WM lesions on MRI had significantly lower overall GM CBF (13.3 ± 2 ml/100 g/min versus 17.7 ± 2.5, < ml/100 g/min p = 0.03).ConclusionMagnetic resonance imaging brain scans performed at term-equivalent age in preterm infants provide quantitative imaging parameters that differ with respect to the degree of prematurity, related to brain maturation.
Highlights
Preterm birth is defined as any live birth occurring before 37 completed weeks’ gestation
Eight were excluded by the quality check due to motion artifacts and a further two infants were excluded from data analysis because reliable quantification of the scalar diffusion parameters could not be undertaken due to major distortions remaining after data processing
Our results showed that the overall cerebral blood flow (CBF) in the gray matter (GM) and all the regional GM CBF values tend to be higher in extremely preterm than very preterm infants, the differences were only significant in occipital and left hemispheric GM after multiple comparison correction
Summary
Preterm birth is defined as any live birth occurring before 37 completed weeks’ gestation. The World Health Organization (WHO) subclassifies preterm infants into the following three groups according to their gestational age at birth: extremely preterms (born before 28 weeks’ gestation), very preterms (28– 32 weeks’ gestation), and moderate to late preterms (32–37 weeks’ gestation). This frequent problem affected 9.6% of all births worldwide in 2005 (Beck et al, 2010), and the number is increasing every year. Apart from the usual cerebral complications directly related to preterm birth, such as leukomalacia and intraventricular hemorrhage, prematurity itself can lead to brain development abnormalities with long-term deleterious effects, but the underlying mechanisms remain unknown. Identification of preterm infants at risk of developing neurodevelopmental disabilities later in life is essential to provide suitable follow-up and more specialized care
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