Advanced Photonics Research Institute: Dr. Tae Joong Eom's research team has developed a photoacoustic imaging technique to reveal the three-dimensional shape of tendons

□ A team of Korean researchers has developed a photoacoustic imaging technique that can eliminate errors when imaging tendons and ligaments.

□ Researchers led by Dr. Tae Joong Eom at the Advanced Photonics Research Institute (APRI, Director Byeong Ha Lee) at the Gwangju Institute of Science and Technology (GIST, President Seung Hyeon Moon) developed a new photoacoustic imaging technology that can reveal the three-dimensional shape of tendons and ligaments, which connect bones and muscles, without distortion or error.

∘ Shoulder tendon disease, one of the major complications of orthopedic surgery, is the most common cause of shoulder pain after middle age and is a very common disease that accounts for 43% of senior referrals to a  hospital. If the degeneration continues, the tendon * will rupture, requiring medical treatment.

* A bundle of fibrous connective tissue that attaches muscles to bones.

∘ Due to the limitations of the tendon diagnostic techniques (ultrasound, MRI) that are commonly used in hospitals, it is difficult to predict the prognosis after the operation and to predict the recurrence of subsequent surgeries. In particular, the most commonly used ultrasound images are required to maintain the direction of the tissue of the acoustic wave and the fibers in the tendon in the vertical direction when photographing the affected part. Distortion of the image signal disappears even if the angle deviates by only 2 degrees and. This increases the likelihood of diagnostic errors.

∘ Therefore, there is a need to overcome the technical limitations of conventional tendon imaging techniques and to develop a new type of tendon structure imaging technique that can meet the requirements for orthopedic diagnosis and treatment.

□ In this study, the researchers used a characteristic of the light absorption of different biomaterials to overcome the limitation of other imaging techniques that creates distortion, such as ultrasound or MRI. When the absorption characteristics of light are used, a constant signal is generated irrespective of the directional light incidence, so any distortions in the image shooting can be reduced.

∘ Using a variety of high-sensitivity spectroscopic methods, the researchers found that collagen, a component of tendons and ligaments, absorbs more laser light than the surrounding tissues. The laser was developed by Dr. Bong-Ahn Yu of the Advanced Photonics Research Institute as a high-performance fiber-optic laser weapon for defense but is being use for medial application.

∘ Because the ultrasound signal is generated by irradiating the laser light of the wavelength optimized for the constituent material of the tendon or ligament, the structure of the tendon or ligament can be photographed without any distortion or error. This technique does not require any special dye or signs, so it is very simple to record tendons and ligaments.

□ Dr. Tae Joong Eom said, "We have developed a new optical imaging technique that can reduce errors of ultrasounds or MRIs for use in the diagnosis of orthopedic surgery by revealing the light absorption characteristics of the tendon which was not known prior to our research."

□ The research was supported by the Gwangju Institute of Science and was published on March 19, 2018, in Scientific Reports.