Novel 3D photoacoustic scanner holds promise for vascular imaging

Researchers from the University College London (UCL) in the UK have developed a high-resolution three-dimensional (3D) photoacoustic scanner based on the Fabry-Perot (FP) ultrasound sensor concept and examined its potential as a tool for clinical vascular imaging.

“Photoacoustic tomography scanners based on an all-optical FP ultrasound sensor can provide highly detailed 3D microvascular images, but minutes-long acquisition times have precluded their clinical use … This limitation has been overcome by variously parallelizing the FP sensor readout, operating at high excitation laser pulse repetition frequencies and employing compressed sensing,” the researchers noted.

“We now demonstrate a practical FP-based scanner that can meet the clinical need for fast acquisition by overcoming the slow speed of early-generation systems,” they said.

The research team evaluated the scanner’s performance on 10 patients from the UCL Hospital who had type 2 diabetes (T2D), rheumatoid arthritis, or breast cancer, plus seven healthy volunteers. [Nat Biomed Eng 2024;doi:10.1038/s41551-024-01247-x]

Use in diabetes

In three T2D patients, the scanner generated detailed 3D images of the microvasculature in the feet, highlighting vessel deformities and structural changes.

“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 have not been able to see exactly what is happening to cause this damage or characterize how it develops,” pointed out senior author Dr Andrew Plumb, Associate Professor of Medical Imaging at UCL, in the news release.

“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, [and allow us to] better understand disease progression more generally,” Plumb continued.

The key technical advance: Reduced acquisition time

Professor Paul Beard, corresponding author and Professor of Biomedical Photoacoustics at UCL, said, “We have 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 5 minutes or longer, images can be acquired in real time, making it possible to visualize dynamic physiological events,” Beard continued.

Clinical applications

“[Taken together,] the level of image detail that [this scanner] provides suggests that it could find application as a tool for the clinical detection, diagnosis, and treatment monitoring of diseases such as diabetes or cancer characterized by microcirculatory abnormalities,” said the researchers.

“The demonstrated combination of high image fidelity, fast acquisition, design versatility, and the practical nature of the technology sets the scene for its clinical translation in oncology, cardiovascular medicine, dermatology, image-guided surgery, and other medical specialties,” they concluded.

The researchers called for further in-depth investigations in larger cohorts to ascertain their findings.