Photoacoustic ‘time-reversal’ technology offers medical imaging potential

A new photoacoustic medical imaging innovation could potentially offer a number of practical advantages over current diagnostic and therapeutic technologies.

Pioneered by Washington University in St Louis, the new technology is called time-reversed adapted-perturbation (TRAP) optical focusing and involves sending guiding light into tissue to seek movement.

Since light that has traversed stationary tissue appears differently than that moving through a dynamic substance such as blood, taking two successive images allows researchers to subtract the light through stationary tissue, retaining only the scattered light due to motion.

They then send the light back to its original source via a process called time-reversal, so it becomes focused once back in the tissue. This allows researchers to better focus light in tissue such as muscles and organs.

Professor Lihong Wang of the university's school of engineering and applied science said: "For example, focusing pulsed light on port wine stains, which are excessive growth of blood vessels, could remove the stains without damaging the surrounding normal skin."