Absolute intracranial blood-flow velocities evaluated by duplex Doppler sonography in asymptomatic preterm and term neonates.

Thirty-eight asymptomatic preterm and term neonates were studied with pulsed Doppler sonography to assess absolute (true) intracranial blood-flow velocities. The middle and posterior cerebral arteries were evaluated by a transcranial approach, and the anterior cerebral artery was evaluated via the anterior fontanelle. Intracranial velocities were seen to increase with increasing gestational age and with increasing age of the neonate. The rate of increase in velocity was greater with higher gestational age. Middle cerebral artery velocities were greater than anterior cerebral velocities. Likewise, antegrade diastolic flow was always seen in these normal neonates. Intracranial velocities increased with gestational age and with increasing age of the child; the resistive index decreased progressively with age.