Novel Rigid Endoscope System Enables Deep Tissue Imaging During Surgery

Hyperspectral imaging (HSI) is an advanced technique that captures and processes information across a given electromagnetic spectrum. Near-infrared hyperspectral imaging (NIR-HSI) has particularly gained prominence in fields like food analysis and industry for its non-destructive capabilities in analyzing object composition. This method involves over-thousand-nanometer (OTN) spectroscopy, which is adept at identifying organic substances, estimating their concentrations, and creating 2D maps. While various HSI devices have been tailored for different uses—from microscope imaging to portable and confined space applications—the challenge has been the loss of sensitivity in standard visible cameras at OTN wavelengths and the scarcity of lenses that can correct chromatic aberrations for such wavelengths. Furthermore, the development of portable NIR-HSI devices requires the construction of cameras, optical systems, and illumination systems capable of operating with a rigid scope, a feature not yet available until now.

Now, a team of researchers led by Tokyo University of Science (TUS, Tokyo, Japan) has developed the world’s first rigid endoscope system capable of HSI from visible to OTN wavelengths. This innovative system integrates a supercontinuum (SC) light source with an acoustic-opto tunable filter (AOTF). The SC light source emits intense coherent white light, while the AOTF can extract light containing a specific wavelength. This setup allows for easy light transmission to the light guide and the ability to electrically switch between a broad range of wavelengths within a millisecond. Tests conducted by the researchers confirmed the system's ability to perform HSI in the range of 490–1600 nm, enabling visible as well as NIR-HSI.

Image: The hyperspectral imaging system extracts molecular vibrations of different resins and distinguishes between them with high reproducibility (Photo courtesy of Hiroshi Takemura from Tokyo University of Science)

The findings highlighted several benefits, such as the minimal light power required for wavelength extraction, which supports non-destructive imaging, and the potential for downsizing. Furthermore, this system can achieve a more continuous NIR spectrum compared to existing rigid-scope-type devices. Going forward, the team plans to enhance the image quality and recall in the visible region and improve the rigid endoscope’s design to better correct chromatic aberrations over a wide area. These advancements are poised to expand the applications of HSI technology, essentially offering "superhuman vision" capabilities in the near future.

“This breakthrough, which combines expertise from different fields through a collaborative, cross-disciplinary approach, enables the identification of invaded cancer areas and the visualization of deep tissues such as blood vessels, nerves, and ureters during medical procedures, leading to improved surgical navigation,” said TUS Professor Hiroshi Takemura. “Additionally, it enables measurement using light previously unseen in industrial applications, potentially creating new areas of non-use and non-destructive testing. By visualizing the invisible, we aim to accelerate the development of medicine and improve the quality of life of physicians as well as patients.”

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