Shedding light on the human body
Optical tomography is used to image the head of a premature newborn infant. Foam-lined helmets are custom built for each infant.
Dr Paul Beard, Professor Dave Delpy, Dr Clare Elwell, Dr Adam Gibson and Dr Jem Hebden - University College London
Dr Caroline Angus and Professor Chris Cooper - University of Essex
A non-invasive technique for monitoring brain function at the cot side of newborn babies has been developed by the Biomedical Optics Research Laboratory at University College London (UCL). Initial results have shown that the technique, known as Optical Tomography, can correctly identify brain activity in newborns when a physiological task is carried out in this case movement of the babies arm. Further refinement of the technique could enable the assessment of brain function in newborns and premature babies as an early indicator of long term outcome. 'This is the only available technique that can provide 3D images of the distribution of blood in the brain at the cot side,' says Adam Gibson of UCL. 'This new work shows that it can be used to image brain function as well.'
Over the past 30 years developments in lasers, optical fibres, electronics and computing have led to dramatic changes in how light can be used to see deep inside the human body. Apart from their world leading work on Optical Tomography, the UCL team, along with the Medical Optics Group at the University of Essex, has pioneered other measurement techniques such as Near Infrared Spectroscopy which is used to measure brain or muscle oxygenation.
Photoacoustic imaging is one of the group's latest techniques and has yet to leave the laboratory. When a short pulse of light travels through tissue, it is absorbed and heats the tissue up slightly. The warmed tissue quickly expands and creates a sound wave that can be detected and analysed to give a high-resolution image showing exactly where the light was absorbed. The technique can identify features that are currently indistinguishable using other scanning methods such as ultrasound or x-rays. 'With this technique we can visualise the structure of very small blood vessels within a tissue,' explains Adam. 'Tumours create characteristic changes in blood vessels so photoacoustic imaging allows us to look at how tumours develop.'