University of TwenteEnschede,
The Netherlands

According to a clinical study published in the scientific journal Photoacoustics, the University of Twente and various European partners have designed a device that shows the difference between healthy fingers and arthritic fingers. The University of Twente and Ziekenhuis Groep Twente researchers responsible for the development of the compact device believe that it may in time help doctors to objectively diagnose the degree of inflammation in joints.

PA/US and US/PD images of an inflamed (upper row) and non-inflamed contra-lateral joint (bottom row) of an RA patient. (Credit: van den Berg, et al., Photoacoustics: 8:12, pp 8–14, 2017)

Several years ago, researchers from the University of Twente joined forces with a number of companies to develop a prototype for a machine that would combine ultrasound and photoacoustics medical imaging techniques. Combining these techniques allows specialists to create images of superficial areas of the body that can offer doctors a wealth of useful information. The idea behind the device was to eventually use it to diagnose arthritis and determine the severity of burns, skin cancer, and hardening of the arteries.

Clinical Study

In the study, the researchers demonstrated that the device is able to clearly show the difference between arthritic and healthy joints. Researcher Pim van den Berg explains: “The signal we measured in arthritic fingers was four to ten times stronger than in healthy fingers.” He says this means the device is able to work at least as well as ultrasound technology.

Seventeen test subjects participated in the study, and researchers were able to successfully demonstrate that this device can in fact be used to diagnose inflamed joints. The researchers expect that the device may also be used in future to determine the degree of inflammation, which they hope to be able to show after a number of improvements currently in the pipeline have been made. Diagnoses become more objective because patients no longer have to depend solely on human observation.

How It Works

The PA/US probe (left) with view of the front end showing the light delivery window (dark aperture) and acoustic lens in medium gray. The patient’s hand is submerged in water (right) where it rests on a series of supports. The probe is mounted on a two-axis motorized stage and positioned above the joint. (Credit: van den Berg, et al., Photoacoustics: 8:12, pp 8–14, 2017)

Ultrasound technology and photoacoustics are two medical imaging techniques that complement each other well. Where ultrasound offers images of structures, photoacoustics generates images that contain more functional information, such as where blood is located.

In photoacoustics, short laser pulses are emitted into a patient’s body. When these laser pulses hit a blood vessel, for example, they cause a small increase in pressure that moves through the body like a sound wave and can be measured on the skin. In ultrasound imaging, the sound is transmitted into the body, where it bounces off of various tissues in a variety of ways and produces waves that can also be detected on the skin.

The paper, titled, “Feasibility of photo acoustic/ultrasound imaging of synovitis in finger joints using a point-ofcare system,” was published by van den Berg, Khalid Daoudi, and Wiendelt Steenbergen from the University of Twente research institute MIRA in cooperation with rheumatologist Hein Moens of Ziekenhuis group Twente. Research has been made possible through EU research grants (including one from the Seventh Framework Programme).