Breakthrough scanner gives premature babies new hope
A scanner that measures particles of light as they travel through the head is helping doctors to assess whether very premature babies are at risk of brain damage.
The £1m machine, which uses a completely new form of optical imaging, has been compared to the early breakthroughs made in ultrasound scanning, which transformed doctors’ ability to see disease in the body’s soft tissues and a baby’s development in the womb.
By sending beams of infrared light through the head of the infant in their first few days of life, the scanner uses a completely new way of creating three-dimensional images of the whole brain.
Blood absorbs light, so by measuring particles of light as they shoot through the brain doctors can see how much is absorbed and assess whether or not the baby has suffered any kind of haemorrhage. Researchers have been working with doctors at the intensive care unit of University College London Hospitals to carry out the first scans of very premature infants in order to see if the baby has suffered an injury after birth, when there is a danger that blood vessels might leak into the undeveloped brain.
There are currently two ways of performing brain scans on babies. Magnetic resonance imaging (MRI) can show brain function, but the babies often have to be sedated before being taken off to the scanner, which carries its own risks. The other technique, ultrasound, can reveal the anatomy of the brain, but does not show how it is functioning in terms of its oxygen supply or blood flow.
The new technique, known as optical tomography, gives doctors 3D images of how much oxygen is in the blood that is getting to the brain. For the first time they can also see much deeper into the ‘white matter’, which contains the more primitive functions of the brain, than is possible with conventional techniques which simply show the grey matter closer to the skull.
The babies are fitted with a tiny, foam-filled helmet out of which protrude dozens of different wires containing the optical fibres that are connected to a laser. The helmet, which incorporates 32 light detectors and 32 kinds of low-intensity light, sends short flashes of infrared light across the brain. The flashes are of much lower intensity than light on an average sunny day in Britain, so no harm can be done.
The machine has been nicknamed Monstir, a catchier version of its full title – ‘Multi-channel Opto-electronic Near-infrared System for Time-resolved Image Reconstruction‘. The time that it takes the light to arrive – and the amount of light absorbed – is measured in nanoseconds (billionths of a second). The whole scan can be performed in eight minutes, and often the baby sleeps through the procedure.
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