Neonatal cerebrovascular studies using Doppler velocity measurements and MRA

Abstract

Magnetic resonance angiography (MRA) studies have shown that cerebral vessels in preterm infants at term age are less tortuous than in term-born infants. The reasons for this are not clear. The aim of this study was to investigate this distinct vascular morphology by comparing contemporaneous MRA with Doppler ultrasound measurements of cerebral blood flow velocity at term age. Sixteen preterm and five term-born infants without overt cerebral pathology underwent Doppler ultrasound measurements of cerebral blood flow velocities and MRA around term equivalent age. Peak systolic, end-diastolic, average mean of the maximum and mean velocity and resistance index were measured on the anterior and middle cerebral arteries. Vessel tortuosity was measured on MRA images. The resistance index was significantly higher in preterm than in term-born infants; this related to the peak systolic velocities tending to be higher and end-diastolic velocities being significantly lower in preterm infants though average mean of the maximum and mean velocities were not different. No significant correlations were found between any of the cerebral blood flow velocity parameters and vessel tortuosity. These differences suggest that cerebrovascular resistance is higher in preterm infants. We postulate that cerebrovascular resistance during the third trimester contributes to vascular development and morphology and that altered resistance may contribute to the suboptimal development of the preterm infant brain.

Keywords

Blood flow velocity - brain - Doppler US - MRA - vessel tortuosity - newborn infant