A research team from the Keck School of Medicine of USC and the California Institute of Technology has developed an imaging platform that combines ultrasound with photoacoustic imaging to generate fast, volumetric scans of both tissue and blood vessels.

Their proof-of-concept study, published in Nature Biomedical Engineering, suggests the technique could help overcome key limitations of MR, CT, and conventional ultrasound.

The system, dubbed RUS-PAT, integrates rotational ultrasound tomography and photoacoustic tomography. RUS-PAT uses a circular array of detectors to reconstruct 3D images, while also capturing signals generated by hemoglobin molecules exposed to laser light. The combined approach allows for wide-field imaging without ionizing radiation or strong magnetic fields.
Researchers demonstrated the technology’s versatility by imaging the brain, breast, hand, and foot. Brain imaging was conducted in patients undergoing surgery for traumatic brain injury, where portions of the skull had been temporarily removed. The system generated images up to 10 centimeters wide in approximately 10 seconds.

“You cannot understate the importance of medical imaging for clinical practice. Our team has identified key limitations of existing techniques and developed a novel approach to address them,” said Dr. Charles Liu, professor of clinical neurological surgery and co-senior author of the study.

The Caltech team is working to address remaining technical hurdles, including image distortion caused by the skull. Modifications to ultrasound frequency are being explored to improve brain imaging without surgical access.

“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 Dr. Lihong Wang, co-senior author and professor of medical and electrical engineering at Caltech.

While still early in development, the researchers see broad clinical potential in neurological, oncological, and vascular imaging. The work was funded by the National Institutes of Health, including grants from the BRAIN Initiative.

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