Scientists create a cutting-edge photoacoustic endoscopy tool employing a see-through ultrasound transducer.
In a recent collaboration, a team of researchers led by Professor Chulhong Kim from the Departments of Electrical Engineering, Convergence IT Engineering, Mechanical Engineering, and the School of Convergence Science and Technology at POSTECH, along with Professor Hyung Ham Kim from similar departments, Dr. Jaewoo Kim from Convergence IT Engineering, and PhD candidate Dasom Heo from Mechanical Engineering, partnered with Professor Hee Man Kim from Yonsei University’s Severance Yonsei Cancer Hospital. Together, they developed the world’s first advanced photoacoustic endoscopy utilizing a transparent ultrasonic transducer. Their groundbreaking research has been published in the journal Science Advances.
Endoscopic ultrasound is a commonly used technique in gastroenterology for cancer detection. However, it has limitations, including poor contrast in soft tissues and primarily providing structural information, which can diminish its diagnostic effectiveness. To tackle these issues, numerous efforts have been made to combine photoacoustic technology with endoscopic ultrasound to enhance tissue vascularity imaging, thereby aiding in earlier cancer detection. Yet, creating a compact probe that can provide high-quality images from both photoacoustic and ultrasound methods has been a significant challenge.
For detailed imaging, it is essential for light and ultrasound to proceed in the same direction. However, prior attempts struggled to achieve this alignment, which had to be either through creating openings in the ultrasonic transducer for light passage or by angling the optical system to line up the two paths. Unfortunately, both methods have drawbacks, typically leading to a compromise in either ultrasound or photoacoustic image quality.
In this innovative study, the team engineered a tiny (1 mm²) transparent ultrasonic transducer that can produce high-resolution ultrasound and photoacoustic images simultaneously. This was accomplished by incorporating a piezoelectric material (PMN-PT) known for its excellent permittivity and suitability for shrinking. Constructed from see-through materials like indium tin oxide electrodes and urethane sound-absorbing layers, this transducer maintains its integrity while allowing light to pass through, facilitating high-quality imaging for both ultrasound and photoacoustic modalities. The researchers managed to integrate both optical and acoustic systems into this miniaturized probe with aligned imaging pathways.
To test their innovative technology, the team placed the device inside a standard endoscope and captured images of a pig’s esophagus. They were pleased to find that they could effectively visualize all the layers from the esophageal mucosa down to the muscle layer, achieving ultrasound performance akin to that of existing commercial endoscopes. Moreover, high-resolution photoacoustic images were obtained even from considerable distances, showcasing the potential of photoacoustic-ultrasound endoscopy for clinical applications.
Professor Chulhong Kim commented, “This advancement is set to overcome the challenges faced by current photoacoustic-ultrasound systems and significantly enhance diagnostic accuracy.” Professor Hee Man Kim from Yonsei Cancer Hospital noted, “The success of these experiments with a transparent ultrasound transducer-based photoacousticultrasound endoscopy system represents a significant step toward creating and localizing cutting-edge diagnostic medical technologies.”
The research was supported by the Basic Research Program of the National Research Foundation of Korea, funded by the Ministry of Education, alongside the BRIDGE project, the Governmental Medical Device R&D Program, and BK21 FOUR, all funded by various ministries including Science and ICT, Trade, Industry and Energy, Health and Welfare, and Food and Drug Safety. Additionally, it received backing from the Deep Science Entrepreneurship Support Program provided by the Ministry of Science and ICT.
