New tech to give 3D capabilities to 2D ultrasound imaging systems

Pengfei Song, a researcher at the Beckman Institute and an assistant professor of electrical and computer engineering and bioengineering at the University of Illinois Urbana-Champaign, is leading the project, which is supported by a four-year, $2m award from the National Institute of Biomedical Imaging and Bioengineering at the US National Institutes of Health.

“Ultrasound is one of the most cost-effective medical imaging technologies,” Song said in a statement. “It’s the natural first stop in increasing accessibility to many clinical applications, such as providing care for patients suffering from cardiovascular diseases or cancer.”

Ultrasound imaging typically uses a handheld probe to send a beam of ultrasonic waves toward a target, like a tumour. Doctors can then determine its size, shape, and location based on how the waves bounce back. A drawback is that clinical ultrasound mostly operates in 2D, which restricts the range of view during a scan.

During a 2D ultrasound scan, a slight change in the angle of the probe or the patient’s posture can make objects appear larger or smaller than they are.

“With 3D ultrasound, you can capture the whole object and surrounding environment, and you have landmarks to know exactly what you’re looking at,” said Matthew Lowerison, a Beckman Institute Postdoctoral Fellow in the Song Lab.

The researchers’ proposed device uses a clip-on technique to integrate with the 2D ultrasound probes that most clinics already own. 3D systems are available in some clinics but are mainly used in high-end facilities for specialised care.

Dubbed FASTER, the device is designed to instantly enable real-time 3D ultrasound imaging for clinics in diverse communities, particularly those where 3D imaging is cost prohibitive.

In FASTER’s first clinical application, which will be conducted in collaboration with the Mayo Clinic in Rochester, Minnesota, the researchers will focus on imaging axillary lymph nodes on patients with breast cancer.

The team added that the versatility of the model means that FASTER will evolve as imaging technology improves.

“With the rapid development of pocket-sized, handheld ultrasound imaging systems, more and more ultrasound imaging procedures can be done by individuals without formal sonography training. 3D imaging is essential in these situations because non-experts can scan the general location in need of attention, and a physician can interpret the images,” Song said.

While a 2D ultrasound scan uses a stationary probe to direct a beam of sound waves in a fixed direction, a 3D ultrasound scan sweeps the beam back and forth. The two most common methods of doing this — manual rotation or automatic motors — can be unwieldy and impractical for scaled-up use.

In their proposal, the team said it will develop the FASTER 3D ultrasound solution using a novel, fast-tilting microfabricated acoustic reflector to achieve high-speed and high-functionality 3D-US imaging.

They added that the acoustic reflector is water-immersible and enclosed in a clip-on device that is compact, lightweight, and low-cost and easily attached to and removed from different types of ultrasound transducers to turn a conventional 2D ultrasound system into 3D.

Unlike conventional 3D-US technologies (such as wobbler transducers and 2D matrix arrays), FASTER does not require the procurement of additional ultrasound transducers for different applications. FASTER achieves a much higher imaging volume rate (up to 1000Hz) than conventional 3D-US technologies. FASTER is compatible also with most ultrasound systems on the market.

In addition to clinical applications, the team believes FASTER could impact basic research in ultrasound, as the device provides a robust, low-cost solution for ultrafast 3D imaging, the foundation for many advanced ultrasound imaging methods, such as shear wave elastography, functional neural imaging, and super-resolution imaging.