RUS-PAT images of the breast of a healthy female subject. Credit: Nature Biomedical Engineering (2026). DOI: 10.1038/s41551-025-01603-5
A new imaging technique promises a faster, more affordable, and more comprehensive way to visualize the human body, potentially revolutionizing medical diagnostics. Researchers have demonstrated a noninvasive method capable of creating 3D images from head to toe.
The technology, detailed in the journal Nature Biomedical Engineering, merges ultrasound and photoacoustic imaging to simultaneously capture images of tissues and blood vessels. This innovation aims to overcome limitations inherent in current medical imaging standards like X-rays, CT scans, MRIs, and traditional ultrasound.
- The new system, called RUS-PAT, combines rotational ultrasound tomography (RUST) and photoacoustic tomography (PAT).
- RUS-PAT can image multiple body regions—brain, breast, hand, and foot—in a single scan.
- The technique offers potential benefits over existing methods, including lower cost, no radiation exposure, and enhanced image detail.
- Researchers are working to refine the system, particularly for brain imaging, where skull distortion presents a challenge.
Addressing Gaps in Medical Imaging
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Medical imaging is fundamental to modern healthcare, guiding decisions across a spectrum of conditions—from injuries and infections to cancer and chronic diseases. However, existing techniques aren’t without drawbacks. Each method has limitations in cost, scan time, depth of penetration, and the level of detail it provides.
“You cannot understate the importance of medical imaging for clinical practice,” said Charles Liu, MD, Ph.D., professor of clinical neurological surgery, urology and surgery, director of the USC Neurorestoration Center, and co-senior author of the research. “Our team has identified key limitations of existing techniques and developed a novel approach to address them.”
How RUS-PAT Works
For the first time in humans, the research team combined rotational ultrasound tomography (RUST) and photoacoustic tomography (PAT) to create RUS-PAT. RUST, similar to a standard ultrasound, directs sound waves into the body. Instead of a single detector, it uses an arc of detectors to reconstruct a 3D image of tissues.
PAT, on the other hand, directs a laser beam into the area, which is absorbed by hemoglobin in the blood. This absorption causes the molecules to vibrate, emitting ultrasonic frequencies that are measured by the same detectors to generate 3D images of blood vessels.
The RUS-PAT system builds upon previous work by the researchers, which demonstrated PAT’s ability to image brain activity. It’s less expensive than an MRI scanner, avoids the radiation of X-rays and CT scans, and provides more detailed images than conventional ultrasound.
“When we think about the critical limitations of current medical imaging, including expense, field of view, spatial resolution and time to scan, this platform addresses many of them,” Liu said.
Broad Applications Across the Body
To demonstrate the versatility of RUS-PAT, the researchers imaged the brain, breast, hand, and foot. Brain imaging was performed on patients with traumatic brain injuries during surgery, with portions of their skulls temporarily removed. The technology captured both tissue structure and blood vessels across a 10-centimeter region in approximately 10 seconds.
“We’ve devised a novel method that changes how ultrasound and photoacoustic imaging systems work together, which allows us to achieve far more comprehensive imaging at meaningful depths,” said co-senior author Lihong Wang, Ph.D., the Bren Professor of Medical Engineering and Electrical Engineering, and Andrew and Peggy Cherng Medical Engineering Leadership Chair. “It’s an exciting step forward in noninvasive diagnostics that doesn’t use ionizing radiation or strong magnets.”
The potential extends beyond these initial applications. Rapid, low-cost foot imaging could benefit the millions affected by diabetic foot complications and venous disease. “This approach clearly has the potential to help clinicians identify at-risk limbs and inform interventions to preserve function in diabetic foot disease and other vascular conditions,” said Tze-Woei Tan, MD, co-author and associate professor of clinical surgery and director of the Limb Salvage Research Program.
“Photoacoustics opens up a new frontier of human study, and we believe this technology will be critical for the development of new diagnostics and patient-specific therapies,” said Jonathan Russin, MD, co-first author of the study and professor and chief of neurosurgery at the University of Vermont.
Challenges and Future Directions
While promising, RUS-PAT isn’t ready for widespread clinical use. A significant hurdle for brain imaging is the distortion of signals caused by the human skull. The Caltech team is exploring adjustments to ultrasound frequency to mitigate this issue. Further refinements are also needed to ensure consistent image quality across all scans.
“This is an early but important proof-of-concept study, showing that RUS-PAT can create medically meaningful images across multiple parts of the body. We’re now continuing to refine the system as we move toward future clinical use,” Liu said.
Publication details
Rotational ultrasound and photoacoustic tomography of the human body, Nature Biomedical Engineering (2026). DOI: 10.1038/s41551-025-01603-5. www.nature.com/articles/s41551-025-01603-5
Journal information:
Nature Biomedical Engineering
