The fluorescent imaging system lays the foundation for f

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Image: Researchers have developed a system that uses dual-wavelength light to provide information about the depth of a tumor in healthy tissue.
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Credit: Kristen M. O’Brien, Washington University in St. Louis

Researchers have developed a simple, low-cost imaging system that uses tumor-targeted fluorescent particles to determine the depth of cancer cells in the body. The portable system could eventually help surgeons distinguish between healthy and cancerous tissue with greater accuracy when removing a tumor.

Doctors can use fluorescent particles during a lumpectomy to make the cancer cells light up so the surgeon can see if there is any cancerous tissue left. However, the equipment needed for this technique is not widely accessible and does not usually provide quantitative information about how deep cancer cells are within tissues. Access to in-depth information will help surgeons remove an entire healthy layer of tissue around the tumor, which has been shown to provide the best possible results for patients.

Research team leader Christine M. O’Brien from the Samuel Achilefu Laboratory in Washington University School of Medicine in St. Louis. “Our group has built on previous work in the field to develop a simple, low-cost system that can rapidly determine the depth of cancer cells using near-infrared (NIR) sensors.”

The researchers describe their new system in the journal Optica Publishing Group Biomedical Optics Express. The portable and easy-to-use system can be used in under-resourced clinical centers, which may help reduce health disparities.

“Systems like this could be used in the future to improve surgical outcomes for patients undergoing lumpectomy,” O’Brien said. It will also prevent the need to wait for pathology results before confirming whether cancer cells are still present after the tumor is removed.

light up cancer

Research has shown that surgical treatments for cancer tend to be more successful if surgeons not only remove the tumor, but also completely remove a healthy layer of surrounding tissue. However, this can be difficult because it is difficult to determine the margins between where the tumor end and the start of healthy tissue. In addition, the optimal thickness of the healthy layer depends on the type and location of the tumor.

To aid in this task, the Achilefu Lab research team led by O’Brien has developed a new tool that relies on applying a single fluorescent dye during a tumor resection that can then excite two different lengths of NIR waves that penetrate different depths in the tissue. The emitted NIR fluorescence can be imaged through the tissue, allowing the detection of tumor cells 1 to 2 cm below the surface.

Dual wavelength fluorescence uses the fact that different colors, or wavelengths of light will travel different distances within tissue. By illuminating tumor-targeting fluorescent molecules at different light wavelengths and comparing their responses, it is possible to predict how deeply tumor-targeting agents are within tissues.

“Multiple research groups have contributed to the development of mathematical relationships linking fluorophore depth to relative fluorescence measurements,” O’Brien said. “The rush of near-infrared contrast agents being developed for use in medicine encouraged us to build on previous work and create a system that works in near-infrared that is also low-cost and easy to use.”

Build a dual wavelength system

A new fluorescent imaging system uses 730 nm and 780 nm LEDs to provide two wavelengths of excitation light and a monochromatic CMOS camera to detect the resulting fluorescence. An 850nm LED has also been incorporated to create a bright image that allows fluorescent images to be linked to a real-world view of the tissue. The researchers decided to use an experimental agent called LS301, which can be administered during lumpectomy, developed in the Achilefu laboratory, as an infrared probe that targets cancer because its broad excitation spectrum prevents the need to use more than one fluorophore, which would make clinical application more complicated. LS301 is currently undergoing clinical trials in breast cancer patients.

After testing the system on synthetic materials layered and sliced ​​from chicken, the researchers evaluated its ability to predict tumor depth from breast tumors grown in mice. This was done by injecting mice with LS301 and then imaging them with the system. It took 5 minutes to take the necessary photos. Calculations based on these images correlated well with the true depth of the tumor, showing a mean error of only 0.34 mm, which is likely acceptable for clinical use.

The researchers are now working to make the system more useful for surgical guidance by speeding up data processing and adding additional automation to the system so that it can scan the entire tissue surface.

paper: C.M. O’Brien, K. Bishop, H. Zhang, X. Xu, L. Shmuylovich, E. Conley, K. Nwosu, K. Duncan, S.B. Mondal, G. Sudlow, and S. Achilefu, “Quantitative Tumor Depth Quantification Using dual-wavelength excitation fluorescence, ” Biomed. He chooses, he decides. pass, Volume 13, Issue 1qq, pp. 5628-5642 (2022).

About Biomedical Optics

Biomedical Optics Express It serves the biomedical optics community with fast, open-access, peer-reviewed papers on optics, photonics, and imaging in biomedicine. The scope of the journal includes basic research, technology development, biomedical studies and clinical applications. It is published monthly by Optica Publishing Group and edited by Ruikang (Ricky) Wang, University of Washington, USA. For more information visit Biomedical Optics Express.

About Optica Publishing Group (formerly OSA)

Optica publishing group It is a division of Optica, formerly known as OSA, Advancing Optics and Photonics Worldwide. It publishes the largest collection of peer-reviewed content in the field of optics and photonics, including 18 prestigious journals, the community’s premier member journal, and papers from over 835 conferences, including 6,500 linked videos. With over 400,000 press articles, conference papers and videos to research, discover and access, Optica Publishing Group represents the full spectrum of research in the field from around the world.

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