The technique, dubbed RSOM (raster-scan optoacoustic mesoscopy), uses a weak laser pulse which excites the tissue of interest.
Absorbed energy heats the tissue slightly, causes momentary expansion, which generates mechanical vibrations at ultrasound frequencies.
Measuring the ultrasound signals allows a high resolution image of what lies under the skin to be reconstructed.
While developing the idea, the team, at the Helmholtz Zentrum München (HZM) and the Technical University of Munich , managed to reduce the scanner to a hand-held.
“This technology, which is easy to use and does not involve any radiation exposure or contrast agent, is allowing us to acquire the first new insights into the disease mechanisms. It also facilitates treatment decisions for the physicians,” said Professor Dr Vasilis Ntziachristos.
Psoriasis (psoriasis vulgaris) is an inflammatory skin disease that is characterised by small to palm-sized patches of severely scaling skin, estimated to affect between ten and fifteen million people in the European Union.
Currently, said the team, doctors evaluate the severity of the disease based on visual assessment of features of the skin surface, such as redness or thickness of the flaking skin.
“Unfortunately, these standards miss all parameters that lie below the surface of the skin, and may be subjective,” said researcher Dr Juan Aguirre. “Knowing the structure of the skin and vessels before treatment can provide the physician with useful information,”
In a recent study, RSOM was used to examining cutaneous and subcutaneous tissue from psoriasis patients.
It allowed determination of characteristics of psoriasis and inflammation including: skin thickness, capillary density, number of vessels, and total blood volume in the skin.
This information was compiled into a clinical index for assessing psoriasis severity that may, said HZM, be superior to the current clinical standard because the new index takes into account characteristics below the skin surface.
Plans are afoot to use RSOM on skin cancer and diabetes (where patients often suffer from damaged blood vessels).
The work has been published in Nature Biomedical Engineering.