In the study, published in Nature Biomedical Engineering, the UCL team delivered photoacoustic tomography (PAT) imaging scans to doctors in real time, providing them with accurate and intricate images of blood vessels to further help inform patient care.
Photoacoustic tomography imaging uses laser-generated ultrasound waves to visualise subtle changes – an early marker of disease – in the less-than-millimetre-scale veins and arteries up to 15mm deep in human tissues.
However, the researcher said that up until now, existing PAT technology has been too slow to produce high-enough quality 3D images for use by clinicians.
During a PAT scan patients must be completely motionless, meaning any movement during a slower scan can cause images to blur and therefore not guarantee clinically useful images.
The older PAT scanners took over five minutes to take an image – by reducing that time to a few seconds or less, image quality is much improved and far more suitable for people who are frail or poorly.
The researchers said the new scanner could help to diagnose cancer, cardiovascular disease and arthritis in three to five years’ time, subject to further testing.
In a statement, corresponding author, Professor Paul Beard, UCL Medical Physics and Biomedical Engineering and the Wellcome/EPSRC Centre for Interventional and Surgical Sciences, said: “We’ve come a long way with photoacoustic imaging in recent years, but there were still barriers to using it in the clinic.
“The breakthrough in this study is the acceleration in the time it takes to acquire images, which is between 100 and 1,000 times faster than previous scanners. These technical advances make the system suitable for clinical use for the first time, allowing us to look at aspects of human biology and disease that we haven’t been able to before.”
Professor Beard added that a key potential use for the new scanner was to assess inflammatory arthritis, which requires scanning all 20 finger joints in both hands. With the new scanner, this can be done in a few minutes, compared to older PAT scanners that can take nearly an hour in total.
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In the study, the team tested the scanner during pre-clinical tests on 10 patients with type-2 diabetes, rheumatoid arthritis or breast cancer, along with seven healthy volunteers.
In three patients with type-2 diabetes, the scanner was able to produce detailed 3D images of the microvasculature in the feet, highlighting deformities and structural changes in the vessels. The scanner was also used to visualise skin inflammation linked to breast cancer.
For some conditions, like peripheral vascular disease (PVD), a complication of diabetes, early signs of changes in tiny blood vessels indicative of the disease can not be seen using conventional imaging techniques such as MRI scans.
But with PAT images they can, thereby offering the potential for treatment before the tissue is damaged and to avoid poor wound healing and amputation, the paper says. PVD affects over 25 million individuals across the USA and Europe, it adds.
Similarly, with cancer, tumours often have a high density of small blood vessels that are too small to see with other imaging techniques.
Dr Nam Huynh from UCL Medical Physics and Biomedical Engineering, who developed the scanner with colleague Dr Edward Zhang, said: “Photoacoustic imaging could be used to detect the tumour and monitor it relatively easily. It could also be used to help cancer surgeons better distinguish tumour tissue from normal tissue by visualising the blood vessels in the tumour, helping to ensure all of the tumour is removed during surgery and minimising the risk of recurrence. I can envisage lots of ways it will be useful.”
Dr Huynh added that a key advantage of the technology was that it was sensitive to haemoglobin; it is light-absorbing molecules like haemoglobin that produce the ultrasound waves.
Looking further ahead, the scientists said that said more research was needed with a larger group of patients to confirm their study’s findings and the extent to which the scanner would be clinically useful in practice.
The research was supported by Cancer Research UK, EPSRC, Wellcome, the European Research Council (ERC) and the National Institute for Health Research University College London Hospitals Biomedical Research Centre.
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