Tag: photoacoustic imaging

Categories : Lab Tests and ImagingTags : 2 Comments

Hand-held Medical Scanner could Transform Cancer and Arthritis Diagnosis

On By ModernMedia
PAT images of wrist vasculature acquired in high-resolution scan mode. Wrist region, (i) x-y and (ii) x-z depth-to-colour encoded MIPs, (iii) x-z and (iv) y-z greyscale MIP slices of regions indicated by dashed red and blue rectangles in (i) showing fine dermal microvasculature (DM), radial artery (RA) and large wrist veins. Inset: x-z greyscale MIP showing cross-sectional view of the radial artery and adjacent veins in the plane indicated by the dashed yellow line in (iv). Huynh et al., Nature Communications, 2024.

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 sub-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 1000 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.

Source: University College London Hospitals

Categories : Lab Tests and ImagingTags :

New Technique Enhances Clarity of Photoacoustic Imaging in Dark Skin

On By ModernMedia
Photo by Nsey Benajah on Unsplash

In photoacoustic imaging, laser light is pulsed through the skin into tissues, which release ultrasound signals with which the internal structure can be imaged. This works well for people with light skin but has trouble getting clear pictures from patients with darker skin. A Johns Hopkins University-led team found a way to deliver clear pictures of internal anatomy, regardless of skin tone. Their technique is described in the journal Photoacoustics.

In experiments the new imaging technique produced significantly sharper images for all people – and excelled with darker skin tones. It produced much clearer images of arteries running through the forearms of all participants, compared to standard imaging methods where it was nearly impossible to distinguish the arteries in darker-skinned individuals.

“When you’re imaging through skin with light, it’s kind of like the elephant in the room that there are important biases and challenges for people with darker skin compared to those with lighter skin tones,” said co-senior author Muyinatu “Bisi” Bell, Associate Professor at Johns Hopkins. “Our work demonstrates that equitable imaging technology is possible.”

“We show not only there is a problem with current methods but, more importantly, what we can do to reduce this bias,” Bell said.

The findings advance a 2020 report that showed pulse oximeters, which measure oxygen rates in the blood, have higher error rates in Black patients.

“There were patients with darker skin tones who were basically being sent home to die because the sensor wasn’t calibrated toward their skin tone,” Bell said.

Bell’s team created a new algorithm to process information from photoacoustic imaging, a method that combines ultrasound and light waves to render medical images. Body tissue absorbing this light expands, producing subtle sound waves that ultrasound devices turn into images of blood vessels, tumours, and other internal structures. But in people with darker skin tones, melanin absorbs more of this light, which yields cluttered or noisy signals for ultrasound machines.

The team was able to filter the unwanted signals from images of darker skin, in the way a camera filter sharpens a blurry picture, to provide more accurate details about the location and presence of internal biological structures.

The researchers are now working to apply the new findings to breast cancer imaging, since blood vessels can accumulate in and around tumours. Bell believes the work will improve surgical navigation as well as medical diagnostics.

“We’re aiming to mitigate, and ideally eliminate, bias in imaging technologies by considering a wider diversity of people, whether it’s skin tones, breast densities, body mass indexes – these are currently outliers for standard imaging techniques,” Bell said. “Our goal is to maximise the capabilities of our imaging systems for a wider range of our patient population.”

Source: John Hopkins University