Quadruple fusion imaging via transparent ultrasound transducer

A quadruple fusion optical and ultrasound imaging system has been developed that allows diagnosis of eye conditions or tumors or to see the environment inside the body using a transparent ultrasound transducer.

Professor Chulhong Kim of POSTECH’s Department of Electrical Engineering, Convergence IT Engineering, and Mechanical Engineering, Dr. Byullee Park of Department of Convergence IT Engineering, Ph.D. candidate Jeongwoo Park of School of Interdisciplinary Bioscience and Bioengineering, Professor Hyung Ham Kim of Department of Convergence IT Engineering, and Professor Unyong Jeong of Department of Materials Science and Engineering, in joint research with Professor Hong Kyun Kim of Kyungpook National University School of Medicine have together developed a transparent ultrasound transducer1 and has used it to produce the world’s first quadruple fusion imaging system that integrates ultrasound imaging, photoacoustic imaging, optical coherence tomography, and fluorescence imaging. These research findings were published in the Proceedings of the National Academy of Sciences of the United States of America (PNAS) on March 8, 2021.

There is a growing interest in multimodal imaging systems that obtain various images and information by combining ultrasound and optical imaging devices. Among them, an ultrasound transducer is a device that produces images by generating ultrasound and functions as an image sensor in ultrasonic examinations. But it was not optically transparent and difficult to let lasers pass through effectively, and therefore had limitations to be coaxially combined with an optical imaging device.

To solve this issue, the research team developed a highly sensitive transparent ultrasound transducer which the laser can effectively pass through. This newly developed device obtains quadruple fusion images of ultrasound, photoacoustic, optical coherence, and fluorescence in one imaging system for the first time.

Using the quadruple fusion imaging system combined with a transparent ultrasound transducer integrated into an ophthalmic imaging system, the researchers were able to observe the corneal neovascularization, structural changes, cataracts, inflammation, and other epidemiological changes in the rat eye.

In addition, when used as a tumor imaging device, the researchers were able to multiparametrically visualize the oxygen saturation of surrounding blood vessels and tissues in a melanoma-afflicted mouse without using a contrast agent. With molecular imaging, breast cancer diagnosis is now possible as demonstrated by acquiring and observing various images of a mouse with breast cancer through injecting a contrast agent that is harmless to the human body.

These research findings are anticipated to be widely applicable to various industries where ultrasound and optical sensors are used, such as healthcare and medical fields, mobile, automobiles, robotics, non-destructive testing, as well as ophthalmological diseases and tumor imaging diagnosis.

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This research was conducted with the support from the National Research Foundation (NRF) of Korea grant funded by the Korean government, the Basic Science Research Program of the NRF of Korea, funded by the Ministry of Education, the National R&D Program of the NRF of Korea, funded by the Ministry of Science and ICT, POSCO Project, and BK21 FOUR Projects.