Nature Photonics (2022). DOI: 10.1038/s41566-022-01068-x” width=”800″ height=”419″/>

Principle of US-OCM for visualization of deep tissues. credit: Photonics of nature (2022). DOI: 10.1038/s41566-022-01068-x

A joint DGIST research team led by Professors Jin Ho Chang and Jae Yong Hwan from the Department of Electrical Engineering and Computer Science has developed the world’s first laser scanning microscopy technology that enables deeper and more detailed observation of biological tissues using gas bubbles transiently produced by ultrasound.

Optical imaging and therapeutic technologies are widely used in scientific research and clinical practice. However, due to the occurrence of optical scattering in the fabrics, light transmission is low. Thus, there is an inherent limitation in deep tissue imaging and processing. This significantly hinders the expansion of the field of application.

To overcome this, in 2017, Professor Jin Ho Chang’s team envisioned the use of micrometer-sized gas bubbles, which are commonly observed when tissues are exposed to high-intensity ultrasound. They developed a technology based on the fact that gas bubbles temporarily created by ultrasound waves cause optical scattering in the same direction as the incident light, thus increasing the depth of light penetration.

In addition, the joint research group of Professors Jin Ho Chang and Jae Yong Hwan focused on expanding the application of optical image technology using gas bubbles caused by ultrasound. A confocal fluorescence microscope is a device that selectively detects fluorescence signals generated in the focal plane of light and provides high-contrast images of microstructures such as cancer cells. It is the most widely used device in scientific research due to its high performance. However, the light focus is blurred at depths greater than 100 μm due to light scattering occurring within the tissue, which greatly limits the application and efficiency of confocal fluorescence microscopy.

In order to maximize the imaging depth of optical imaging techniques such as confocal fluorescence microscopy, the photons that make up the irradiating light must not have a phenomenon in which the direction of their propagation is distorted by light scattering in tissues. However, the previously developed method, based on gas bubbles rarely created by ultrasound, was not the solution.

Therefore, this collaborative research group developed ultrasound technology to create a bubble bed in a desired area with dense gas bubbles (90% density or more) in living tissue and to preserve the generated gas bubbles during image acquisition. In this gas bubble layer, the direction of photon propagation is not distorted.

Thus, it has been experimentally proven that light focusing is possible even in deeper biological tissues. In addition, by applying this technology (i.e., ultrasound-induced tissue transparency) to a confocal fluorescence microscope, ultrasound-induced optical clearing microscopy (US-OCM) named in this study was developed for the first time in the world. the imaging depth is six times greater than that of conventional confocal microscopy.

In particular, the US-OCM developed in this study did not cause any tissue damage because when the ultrasound irradiation was stopped, the generated gas bubbles disappeared, and Art optical properties returned to the generation of gas bubbles, believing it to be harmless to the living body.

Professor Jin Ho Chang from DGIST’s Department of Electrical Engineering and Computer Science says that “by working closely with experts in ultrasound and optical imaging, we were able to overcome the limitations inherent in existing optical imaging and treatment technologies.”

“The technology derived from this research will be applied to a variety of optical imaging techniques, including multiphoton microscopy and photoacoustic microscopy in addition to several optical treatments including photothermal therapy and photodynamic therapy. This would improve the application of existing technologies, increasing their image and depth of processing.’

The results of this study were published in Photonics of nature.

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Additional information:
Haemin Kim et al., Deep Laser Microscopy Using Optical Cleaning of Ultrasound-Induced Gas Bubbles, Photonics of nature (2022). DOI: 10.1038/s41566-022-01068-x

Courtesy of DGIST (Daegu Kenbuk Institute of Science and Technology)

Citation: Medical optical imaging using world’s first ‘ultrasound-induced tissue transparency’ technology (2022, October 7) Retrieved October 7, 2022, from imaging-world-ultrasound -induced.html

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