Cranial ultrasound

Cranial ultrasound is a technique for scanning the brain using high-frequency sound waves. It is used almost exclusively in babies because their fontanelle (the soft spot on the skull) provides an 'acoustic window'. A different form of ultrasound-based brain scanning, transcranial Doppler, can be used in any age group. This uses Doppler ultrasound to assess blood flow through the major arteries in the brain, and can scan through bone. It is not usual for this technique to be referred to simply as 'cranial ultrasound'. Additionally, cranial ultrasound can be used for intra-operative imaging in adults undergoing neurosurgery once the skull has been opened, for example to help identify the margins of a tumour. Cranial ultrasound is a technique for scanning the brain using high-frequency sound waves. It is used almost exclusively in babies because their fontanelle (the soft spot on the skull) provides an 'acoustic window'. A different form of ultrasound-based brain scanning, transcranial Doppler, can be used in any age group. This uses Doppler ultrasound to assess blood flow through the major arteries in the brain, and can scan through bone. It is not usual for this technique to be referred to simply as 'cranial ultrasound'. Additionally, cranial ultrasound can be used for intra-operative imaging in adults undergoing neurosurgery once the skull has been opened, for example to help identify the margins of a tumour. Most neonatal units in the developed world routinely perform serial cranial ultrasound scans on babies who are born significantly premature. A typical regimen might involve performing a scan on the first, third and seventh day of a premature baby's life, and then at regular intervals until the baby reaches term. Premature babies are especially vulnerable to certain conditions involving the brain. These include intraventricular haemorrhage (IVH), which often occurs during the first few days, and periventricular leukomalacia (PVL), which tends to occur later on. One of the main purposes of routine cranial ultrasound scanning in neonatal units is to identify these problems as they develop. If severe intraventricular haemorrhage is noted then the baby will need to be scanned more frequently in case post-haemorrhagic hydrocephalus (swelling of the ventricles as the natural flow of the cerebrospinal fluid is blocked by blood-clots) develops.