Scientists from Caltech and USC have developed RUS-PAT, a new 3D imaging technique that combines ultrasound with laser light. This hybrid system captures both anatomical structure and blood vessel function in high-resolution, “optical colour”
Researchers from the California Institute of Technology (Caltech) and the University of Southern California (USC) have developed a hybrid imaging system that provides three-dimensional, colour-coded views of the human body.
The technique, called hybrid rotational ultrasound and photoacoustic tomography (RUS-PAT), integrates two distinct modalities to capture both the physical structure of soft tissues and the functional details of the blood vessels within them.
The study, published in the January 16, 2026, issue of Nature Biomedical Engineering, demonstrates how the system can visualise complex anatomy such as the brain, breast, hand, and foot in under one minute.
Bridging structure and function with RUS-PAT
Standard ultrasound is a staple of clinical medicine because it is fast and affordable, but it generally provides two-dimensional images and struggles to show functional details of blood flow. Photoacoustic tomography (PAT), a field pioneered by Caltech’s Lihong Wang, uses laser pulses to make molecules in the body vibrate. These vibrations create sound waves that detectors can map to show the “optical colour” of the vasculature, revealing how blood moves through veins and arteries.
By combining these two methods into the RUS-PAT platform, the team has created a tool that provides both morphological and functional data simultaneously. This dual-contrast approach allows clinicians to see exactly where a tumour or injury is located while also monitoring oxygen supply and blood vessel health.
Innovative design and efficiency using an ultrasonic transducer
To make the system practical for clinical use, the researchers developed a design that uses a single-element ultrasonic transducer to broadcast waves across a wide field. A small number of arc-shaped detectors then rotate around the target area. This allows the device to function like a high-end hemispheric detector but at a significantly lower cost and complexity.
In human trials, the system achieved a 10-centimetre field of view with submillimetre resolution. Unlike CT scans or MRIs, RUS-PAT does not require ionising radiation, strong magnets, or expensive contrast agents.
Clinical applications and future reach
The research team has identified several high-priority applications for the technology:
- Oncology:
- Improving breast tumour imaging by revealing a tumour’s exact location alongside its physiological state.
- Diabetes:
- Monitoring nerve damage and blood supply in patients with diabetic neuropathy.
- Neurology:
- Observing structural details and hemodynamics in the brain.
The current prototype, which houses the scanners beneath a specialised bed, can reach a depth of approximately 4 centimetres. The researchers are now exploring endoscopic light delivery to reach deeper tissues and investigating ways to refine signal clarity through the human skull for broader brain imaging applications.
