Prematurity and brain perfusion: Arterial spin labeling MRI

Abstract

Purpose: Abnormal brain perfusion is a critical mechanism in neonatal brain injury. The aim of the present study was to compare Cerebral Blood Flow (CBF) evaluated with ASL MRI in three groups of neonates: preterms without brain lesions on MRI (PN), preterms with periventricular white matter lesions (PNp) and term neonates with normal MRI (TN). The correlation between CBF and clinical outcome was explored.

Materials and methods: The institutional review board approved this prospective study and waived informed consent. The perfusion ASL data from 49 consecutive preterm neonates (PN) studied at term-equivalent age and 15 TN were evaluated. Statistically significant differences in gray matter CBF were evaluated by using a linear mixed-model analysis and Mann-Whitney U test. Logistic regression analysis was used to assess the relation between CBF and neuromotor outcome at 12 months.

Results: Comparison of means indicated that the CBF of the whole brain were significantly higher in PN compared to TN (P = 0.011). This difference remained significant when considering the frontal (P = 0.038), parietal (P = 0.002), temporal (P = 0.030), occipital (P = 0.041) and cerebellar (P = 0.010) gray matter. In the PN group, lower CBF in basal ganglia was associated with a worse neuromotor outcome (P = 0.012).

Conclusions: ASL MRI demonstrated differences in brain perfusion of the basal ganglia between PN and TN. In PN, a positive correlation between CBF and neuromotor outcome was demonstrated in this area.

Keywords: ASL, arterial spin labeling; Brain perfusion; CBF, cerebral blood flow; HIE, hypoxic-ischemic encephalopathy; Neonate; PN, preterm neonate with normal MRI; PNp, preterm neonate periventricular white matter lesions; PVL, periventricular leukoencephalopathy; Prematurity; TN, term neonate with normal MRI.

Fig. 1

Flowchart of the pipeline used for ASL data analysis.

Fig. 2

Regional mean CBF (ml of blood/100 mg/min) in the three groups of neonates (dark gray: TN, lite gray: PN, gray: PNp). *PN vs TN; †PNp vs TN; **PN vs PNp P < 0.05.

Fig. 3

ASL maps of three preterm neonates. A) and B) CBF maps of two PN who presented normal and abnormal outcome respectively, showing reduced perfusion of basal ganglia in B. C) CBF map of a PNp neonate showing a global reduction of brain perfusion. Color scale indicates CBF (ml/100 mg/min).

Fig. 4

PN presenting pathological outcome at 12 months showed lower CBF values in the basal ganglia region. The CBF of the basal ganglia resulted to be an independent predictive factor for neuromotor outcome at 12 months in the PN group.