Medical imaging breakthrough could transform cancer and arthritis diagnosis

A new hand-held scanner developed by UCL researchers and tested in a series of clinical trials on UCLH patients can generate highly detailed 3D photoacoustic images in just seconds, paving the way for their use in a clinical setting for the first time and offering the potential for earlier disease diagnosis.

In the study, published in Nature Biomedical Engineering, the UCL and UCLH team show their technology can deliver photoacoustic tomography (PAT) imaging scans to doctors in real time, providing them with accurate and intricate images of blood vessels, helping 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, up until now, existing PAT technology has been too slow to produce high-enough quality 3D images for use by clinicians.

The older PAT scanners took more than 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 say the new scanner could help to diagnose cancer, cardiovascular disease and arthritis in three to five years’ time, subject to further testing.

In this study, the team tested the scanner during pre-clinical tests on 10 UCLH patients with type-2 diabetes, rheumatoid arthritis or breast cancer, along with seven healthy volunteers. They also compared the PAT scans to regular clinical scans taken at UCLH. Larger scale trials of the device are ongoing at UCLH and UCL.

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 the skin inflammation linked to breast cancer.

UCLH consultant radiologist Andrew Plumb, a senior author of the study and Chief Investigator of the clinical PAT studies, said: “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. 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.” Dr Plumb is also Associate Professor of Medical Imaging at UCL.

Patients were identified and recruited from a number of clinics at UCLH, including consultant rheumatologist Madhura Castelino, consultant interventional radiologist Conrad von Stempel and research staff Katerina Soteriou and Antonia Yeung who co-ordinated safe, timely scanning at UCLH and UCL on the new PAT scanner.

UCL Professor of Biomedical Photoacoustics Paul Beard, corresponding author, 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.

“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 five 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.

“Now more research is needed with larger groups of patients to confirm our findings.”

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 – older PAT scanners take nearly an hour, which is too long for elderly, frail patients, he said.

This research was supported by Cancer Research UK, the Engineering & Physical Sciences Research Council, Wellcome, the European Research Council and the National Institute for Health Research University College London Hospitals Biomedical Research Centre.