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A collaborative research team led by Professor Chulhong Kim from POSTECH, alongside colleagues from various departments including Electrical and Mechanical Engineering, and Convergence Science and Technology, has partnered with Professor Hee Man Kim from Yonsei University’s Severance Yonsei Cancer Hospital. Together, they have innovated what is being hailed as the first high-performance photoacoustic endoscopy utilizing a transparent ultrasonic transducer. Their significant findings were published in the journal Science Advances.
Endoscopic ultrasound has become a crucial tool in gastroenterology, particularly for cancer diagnostics. However, its efficacy is limited by poor contrast in soft tissues and a predominance of structural data, which can hinder precise detection. In attempts to enhance early cancer identification, researchers have explored integrating photoacoustic technology with endoscopic ultrasound to provide clearer insights into tissue vasculature. A key challenge has been achieving high-quality imagery from both modalities simultaneously within a compact probe.
The successful acquisition of high-resolution images relies on the precise alignment of light and ultrasound paths. Past attempts struggled with this alignment, leading researchers to either drill into the ultrasonic transducer to create a clear light path or manipulate the optical system into a tilted orientation. Both strategies resulted in compromises that impacted the quality of either ultrasound or photoacoustic imaging.
The innovative approach taken by this research team led to the creation of a remarkably compact transparent ultrasonic transducer measuring just 1 mm². This transducer permits high-resolution simultaneous imaging of both ultrasound and photoacoustic sources. Utilizing a piezoelectric material known as PMN-PT, characterized by its high permittivity, the team constructed the transducer from transparent components such as indium tin oxide electrodes and urethane sound-absorbing layers, maintaining the structural integrity needed for light passage while enhancing imaging capabilities. This design was pivotal in achieving effective integration and alignment of optical and acoustic systems within the probe.
To test their groundbreaking technology, the researchers tested the device within a commercial endoscope, capturing detailed images of a porcine esophagus. They successfully visualized all anatomical layers from the mucosa to the muscle layer, achieving ultrasound performance on par with leading commercial endoscopes. Moreover, they obtained high-resolution photoacoustic images at significant distances, indicating promising clinical applications for this photoacoustic-ultrasound endoscopic system.
Professor Chulhong Kim from POSTECH noted the importance of this development, stating, “This breakthrough is anticipated to address the limitations seen in current photoacoustic-ultrasound systems, significantly enhancing diagnostic precision.” Complementarily, Professor Hee Man Kim of Yonsei Cancer Hospital emphasized the importance of these results, suggesting they represent a significant advancement towards the creation and localization of innovative diagnostic medical devices.
This research initiative received backing from various Korean governmental programs, including the Basic Research Program by the National Research Foundation of Korea under the Ministry of Education, as well as the BRIDGE project sponsored by the Ministry of Science and ICT. Additional support came from the Governmental Medical Device R&D Program and the BK21 FOUR initiative, funded by multiple ministries ranging from Science and ICT to Health and Welfare.
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