Diffusion-weighted imaging in neonates

Diffusion-weighted imaging (DWI) can readily be performed in the neonate, a lthough currently studies remain a few years behind those carried out on ad ults. DWI relies on the random diffusion of water molecules. As for the adu lt population, a pulsed gradient spin echo sequence (PGSE) with cardiac gat ing can be used to exploit the effect of diffusion on image contrast and to determine the apparent diffusion coefficient (D*) for tissues or fluids. A nisotropic properties caused by the restriction of the movement of water mo lecules may be demonstrated. In the neonatal brain restricted motion can be detected in both myelinated and unmyelinated white matter tracts. DWI has been used to study changes in global and focal ischaemic injury to the neon atal brain. A decreased D* may be documented after an ischaemic insult foll owed by a gradual increase. These changes are consistent with animal data b ut show a slower time course. Intervention following perinatal ischaemic in jury must be started within hours. DWI detects early ischaemic injury and m ay therefore be a useful tool for identifying those infants who could benef it from intervention.