Diamonds Help UT Researchers Study Stroke

Sparkling. Regal. Timeless. Diamonds have been called a girl’s best friend, but could they also help us see deeper into the vasculature of the brain? According to a new paper in Light: Science & Applications, UT Austin researchers have found they do.

The paper describes how a team from Biomedical Engineering Professor Andrew Dunn’s laboratory built a Diamond Raman Laser that when used with another high-powered laser, combines established imaging techniques—laser speckle imaging with multi-photon fluorescence microscopy—to view deeper into the brain. Researchers want to see what’s happening in the brain so that they can better study the effect of stroke and neurodegenerative diseases in small animal models, which could lend insights into human health.

The diamond laser allows researchers to image routinely at depths beyond 1 millimeter, which is almost twice as deep as with a conventional laser.

While the rectangular rock that Dunn’s team uses doesn’t exactly resemble a treasure you’d buy for your sweetheart—it’s still purer than most naturally occurring diamonds because it happens to be synthetic.

diamond laser dunn

What it looks like: Although not as sparkly as an engagement ring, this synthetic diamond possesses an optical property that makes it an ideal tool to use in combination with high-powered lasers to image deep brain tissue. 

Why use diamonds? In addition to being the most popular type of engagement ring, diamonds also possess an outstanding optical property: they are able to undergo Raman scattering, which makes it possible to shift the wavelength, or color, of light.

Researchers first use a high-powered laser that produces ultra-short femtosecond pulses of light at a wavelength of 1 micrometer. They then take the output from that laser and send it to the Diamond Raman Laser. The optical properties of the diamond shift the color of the light to a longer wavelength. It’s this combination of ultra-short pulse duration with a longer wavelength that enables a more efficient way to conduct multiphoton fluorescence imaging and to see deeper into brain tissue.

Dunn and his team use this imaging technique to study stroke. One of their goals is to create a complete 3-D map of the blood vessels of the brain in an animal model so that they can monitor what parts of the brain are affected during a stroke event, and what, if any, parts of the brain are reactivated through rehabilitation. Such an understanding could lead to improved rehabilitation therapies for stroke victims.

With the Diamond Raman Laser technique, Dunn’s team is able to monitor how complicated brain vasculature network changes over time. Researchers will be able to see how vasculature changes in a normal brain, how the brain changes during stroke, and how various types of post-stroke rehabilitation techniques (such as drug therapies or physical therapy) may influence regrowth of the brain’s blood vessels.

The Diamond Raman Laser also holds promise in neurodegenerative disease research.

“There’s growing evidence that there may be a vascular basis for Alzheimer’s,” Dunn says, “so the Diamond Raman Laser could image parts of the brain and provide mapping that could be valuable to learning how Alzheimer’s progresses.”

Not only does the Diamond Raman Laser technique allow for imaging to be done in live animal models, it’s also more affordable. Current commercial laser methods that are able to image deep brain tissue cost hundreds of thousands of dollars, while the Diamond Raman Laser costs about $10K to build.

Andrew Dunn directs the UT Austin Center for Emerging Imaging Technologies, which brings together researchers, engineers, physicians, and scientists to build on strengths in optical imaging, biomedical optics, ultrasound, and image processing to create novel imaging approaches for understanding basic biological processes as well as clinical applications in the diagnosis and treatment of diseases.