Reporter 464, 26 March 2001
Ultrasound is a well-known technique for pregnancy scanning, but at the University of Leeds it is enabling major advances in areas as diverse as early detection of breast tumours, measuring flow from oil wells and prolonging the shelf life of milk. Researchers are even developing a sonar virtual reality where you can feel what it’s like to be a bat!
The way bats navigate and find their food – echo location – is the basic concept behind ultrasound technology. Scientists use ultrasound scanners to map unseen objects, or determine the details of the substance through which the soundwaves have passed.
Quicker diagnosis – Heather Venables compares ultrasound images of breast tumours
Early detection is vital for effective treatment of breast cancer, and Heather Venables of Healthcare Studies is looking at the factors which limit the sensitivity of ultrasound breast scans, especially in detecting tumours in the early stages of growth. The main indication of a tumour becoming malignant is that it gains its own blood supply – and ultrasound can detect increased blood flow whereas traditional mammographs cannot.
"It’s early days yet, but I hope my research may identify better ways to use the technique, to help determine the earliest possible detection of malignant tumours," said postgraduate student Heather.
Keeping it fresh – Dr Malcolm Povey with samples of milk ultrasound tested to determine their shelf life
Blood is not the only moving liquid which ultrasound techniques can scan. Leeds is one of the world leaders in an innovative technology using ultrasound to look inside industrial processes as they happen.
Process tomography uses up to 36 ultrasound scanners at a time to get an all round image of activities such as the flow from oil fields. This flow is usually a mixture of oil, gas, mud and water in varying amounts. Oil companies need to log each well’s output to extend the lifetime of the field and to separate and dispose of unwanted substances.
"Current methods of testing and measuring are costly and time-consuming and can only take place periodically," says Professor Brian Hoyle, who leads this reseach. "Ultrasound can test the output instantaneously and constantly, which could save oil companies over £1m per well."
As a non-invasive means of testing, ultrasound is also ideally suited to the study of foods, and is both safe and hygienic. Food science researcher Malcolm Povey is currently looking at new applications for ultrasound in food testing. He uses the Ultrasizer, a new machine developed by Malvern Instruments, to measure the changes in sound waves passed through milk. By doing so he can calculate the size of the fat globules which determine how close it is to becoming a solid – in other words, how fresh it is.
The sensitivity of the Ultrasizer means it may be possible to ‘fingerprint’ foods, and then test for any adulteration of the substance.
Olive oil is sometimes mixed with cheaper oils by unscrupulous traders, or butter oil removed from milk and replaced with a cheaper alternative. "As well as checking the purity of foodstuffs, we can detect nasty materials like cherry stones, glass or plastic in substances like yoghurt," said Dr Povey.
"We can increase the shelf life of milk without any additives, just by reducing the size of the fat globules using physical rather than chemical techniques. Basically, the result is high quality, tastier and safer food which costs less to produce."
Scientific pioneer – the bat’s echo location system has inspired a variety of research
Dr Dean Waters specialises in bats and how they use soundwaves to find their way around. He is currently developing a virtual reality scenario in which a person uses echo location to find a moth, just as bats find their food. "We’ve been testing the signals from fruit bats to see how they navigate obstacles," he said. "Our findings, and the scenario we’ve created could enable people with visual disablities to have access to virtual reality."
Dr Waters also worked with Professor Deborah Withington on a revolutionary device which will allow blind people to ‘see’ what surrounds them. The ‘spatial imager’ is fitted with tiny transmitters and receptors which send and receive ultrasound signals in the same way as bats do when manoeuvring in the dark. The results are then sent as small vibrations to the handle of the stick, which lets the user know the exact position of obstacles, not only in front of and around the user, but also overhead. The device is currently being tested and could be on the market as early as next year.
Sound expert – Deborah Withington
A collaborative project between the departments of Healthcare Studies and Medical Physics has also used ultrasound to diagnose and monitor osteoporosis in adults by scanning their heel bones. To help ensure the reliability of the findings, Dr Tony Evans developed a ‘phantom bone’ which could be tested to verify that the results were consistent. The phantom heel is made of resin with a central section which mimics bone marrow, so that its structure is similar to bone in terms of its ultrasound properties. Development of the product is continuing for use in other situations.
Dr John Truscott, who worked with Tony Evans on the osteoporosis project, is also using ultrasound scans to discover whether health education can have a positive effect on growth. Children from a local primary school underwent ultrasound bone scans of their fingers, and were then given advice on diet and exercise. Dr John Truscott is testing the same children, now in secondary school, to monitor any changes.
"We hope to extend this technique for use with premature babies, by developing a new machine to test the humerus," he said. "This would be a totally new departure, but the advantage of ultrasound is that it is not radiative – unlike traditional X-rays – and so pre-term babies can be monitored more frequently for proper growth. Ultrasound is also more flexible, in that it can be used at the ‘cot-side’, so reducing the disturbance for the babies."
For more information, see the Sound Alert website
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