Cerebrospinal fluid flow void in children.

We studied the frequency and clinical value of cerebrospinal fluid flow void in 49 normal children who underwent MRI on a 0.35 T unit. T2-weighted axial SE images were retrospectively analysed to determine relative signal intensities of the fourth, third and lateral ventricles and the cerebral aqueduct, rated as high intensity, low intensity, and no signal (flow void). Flow void was seen in the fourth ventricle in 20% of children up to 3 months of age, 67% from 4 to 6 months of age, in all children aged between 7 months and 2 years and in about half of those aged more than 3 years. In cerebral aqueduct the figures were 40% up to 1 month, age, 80% at 2-3 months and 100% above 4-6 months of age, and in the third ventricle 0% up to 1 month, 60% at 2-3 months, 67% at 4-6 months, and almost 100% in above 7 months. Flow void was much more frequent at 1-6 years of age than in adults and less frequent in neonates, which may reflect the different compliance of the growing brain.