Brain ultrasonography in the premature infant

Abstract

Brain ultrasonography plays a central role in the detection and management of neonatal disease in the preterm infant. Although morphological study, using high-frequency transducers, remains the cornerstone of imaging, pulsed and colour Doppler scans provide additional information and improve the diagnostic and prognostic accuracy of ultrasonography. Particular features of normal brain US in the extremely preterm infant are reported. Cerebral haemorrhage and its different patterns (intraventricular haemorrhage and periventricular hemorrhagic infarction) are described. The value of Doppler techniques is emphasized, e.g. demonstration of coloured signal within the aqueduct of Sylvius, visualization of patency of the terminal veins, demonstration of Doppler spectrum fluctuations, recognition of low blood flow, and the detection of vasodilatation. The sonographic diagnosis of periventricular leucomalacia and its difficulties are documented. Some uncommon brain lesions of the premature infant are illustrated, e.g. gangliothalamic ischaemic damage, cortical necrosis, focal infarcts, etc. The importance of repeating the US examinations until near term is highlighted.

The rationale for routine cerebral ultrasound in premature infants

“…Cerebral US is a non-invasive, radiation-free imaging technique that can be performed without sedation at the bedside of intubated, ventilated infants who would be difficult to examine using MRI outside an MR-compatible incubator [1]. But is US accurate enough when compared with the gold standard for brain imaging, which is MRI?…”

“…The brain US examination consists of grey-scale imaging of the brain parenchyma and colour/pulsed Doppler of the vessels [1]. Sectorial with small footprint (5-to 8-MHz) and linear-array (5-to 12-MHz) transducers should be used.…”

“…Post-haemorrhagic hydrocephalus, which can be communicating or non-communicating, is another complication of intraventricular haemorrhage [1,2]. The incidence of posthaemorrhagic ventricular dilation is 36%, and this resolves in approximately 65% of cases [1].…”

“…The incidence of posthaemorrhagic ventricular dilation is 36%, and this resolves in approximately 65% of cases [1]. Cerebellar abnormalities, mainly haemorrhage, infarction and underdevelopment, are being increasingly recognized and these have been associated with very low birth weight [4,8].…”

“…Various imaging techniques, mainly US and MRI, have been used for this purpose [1,2]. US was the first imaging modality to be used, in the 1980s.…”