Imma Perfetto
Cosmos science journalist
It’s not the famous Star Trek tricorder but it’s close: researchers have developed a hand-held scanner that can generate highly detailed 3D images of body parts in almost real time.
The technology can accurately image blood vessels up to 15mm deep in human tissue, which the researchers say could help to diagnose conditions such as cancer, cardiovascular disease, and arthritis.
“We’ve come a long way with photoacoustic imaging in recent years, but there were still barriers to using it in the clinic,” says Paul Beard of University College London (UCL), UK, corresponding author of the new Nature Biomedical Engineering paper.
“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.
“This speed avoids motion-induced blurring, providing highly detailed images of a quality that no other scanner can provide. It also means that rather than taking 5 minutes or longer, images can be acquired in real time, making it possible to visualise dynamic physiological events.
“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.”
PAT is based on the photoacoustic effect, which occurs when materials absorb light and produce sound waves.
A PAT scanner fires very short laser bursts at biological tissue and some of this light is absorbed depending on the colour of the target. This causes a slight increase in heat and pressure, which in turn generates an ultrasound wave containing information about the tissue that is picked by the scanner.
Beard and colleagues reduced the time needed to acquire the images by making innovations in the scanner design and the mathematics used to generate the images.
The new scanner detects the ultrasound waves at multiple points on the tissue surface simultaneously, rather than measuring them at more than 10,000 different points one at a time.
New mathematical principles, similar to those used in digital image compression, then allowed the images to be reconstructed from just a few thousand (rather than tens of thousands) of measurements.
The technology is sensitive to light-absorbing molecules like haemoglobin and can be used to image changes in tiny blood vessels, which can’t be seen using conventional imaging techniques such as MRI scans. As a result, PAT imaging has applications in conditions such as cancer, in which tumours often have a high density of small blood vessels, and in peripheral vascular disease (a complication of diabetes).
The team tested their technology on 10 patients with type 2 diabetes, rheumatoid arthritis, or breast cancer, and healthy volunteers. They were able to produce detailed 3D images of the skin inflammation linked to breast cancer and the microvasculature in the feet of diabetics.
“One of the complications often suffered by people with diabetes is low blood flow in the extremities, such as the feet and lower legs, due to damage to the tiny blood vessels in these areas,” says study senior author Andrew Plumb of UCL.
“But until now we haven’t been able to see exactly what is happening to cause this damage or characterise how it develops.
“In one of our patients, we could see smooth, uniform vessels in the left foot and deformed, squiggly vessels in the same region of the right foot, indicative of problems that may lead to tissue damage in future.
“Photoacoustic imaging could give us much more detailed information to facilitate early diagnosis, as well as better understand disease progression more generally.”
The scientists say more research is needed with a larger group of patients to confirm their findings and the extent to which the scanner would be clinically useful in practice. They exp-ect it mi9ght be available in 3 to 5 years.
