Quantification of aortic pulse wave velocity in preterm infants using 4D phase contrast MRI

Background 4D phase contrast (PC) MRI sequences providing full coverage of the aortic arch were acquired in neonates. Aortic pulse wave velocity (PWV) was then calculated from flow measurements taken at 5 to 8 locations along the arch and the aortic length between each location. Neonatal PWV values were compared with previously published adult values. Mechanical compliance within the healthy and diseased aorta has been well documented in adults and paediatrics [1,2]. Metafratzi et al [1] reported a PWV range from 4 to 10 ms-1 in the healthy adult aorta, whilst Vulliemoz et al found a mean PWV of 4.4 ms-1 [3]. PWV is an inverse measure of vessel compliance and marker for vessel stiffness. A significant increase in PWV has been found in paediatric subjects born prematurely at low birthweight when studied at ~8yrs and may explain the increase in cardiac disease in this population[2]. However PWV models do not extend back to preterm infants. Recent studies in adults have used PC MRI flow data to determine PWV [4].