By Asher Garonzik
Two hundred years ago, if you visited the doctor’s office complaining of wrist pain, chances are you’d wind up with a leech fastened to your gut. A century later, you’d at least be able to zero in on the cause with an X-ray. Since then, the arsenal of medical apparatuses for diagnosis and treatment has moved steadily toward the more efficient and effective. Though in another hundred years we may look back on current devices as obsolete relics, in recent decades advances in health care technology have surged into medical offices nationwide, granting today’s patients more safe and effective care than ever before.
Since the creation of the university’s Biomedical Engineering Department in 2001, professors such as Drs. Andrew K. Dunn (PhDBME ’97) and James W. Tunnell (BSEE ’98) have been exploring the frontiers of biomedical research. Although one professor studies blood flow and the other skin cells, both work with new experimental methods of gathering information by manipulating light and interpreting its interaction with human tissue.
The Future of Blood Flow Imaging
Dunn’s focus is neural function. He and his students spend their days in the lab working out new and improved ways to determine the causes of and processes involved in conditions such as stroke, migraines and Alzheimer’s disease. More specifically, his team uses a sophisticated, cost-effective technique called “laser speckle contrast imaging” to shed light on the complex properties of the brain’s blood flow.
Dr. Andrew Dunn directs this laser on brain tissue to image blood flow.
Photo by Erin McCarley
Laser speckle itself is a principle of physics that occurs when coherent light—such as a laser beam—reflects from a rough, scattering surface such as tissue. Dunn shines coherent light on brain tissue and films the results as the light beams ricochet off it. Over time, he captures an extremely accurate picture of the blood flow in a particular area of the brain. The end product resembles a highly detailed moving X-ray of the brain’s blood vessels.
The laser speckle technique represents a technological jump forward for several reasons. Until now, the main precursor to the laser speckle method has been the laser Doppler, a fiber-optic probe about a square millimeter in size that is placed on the brain. The laser Doppler, still the standard approach to imaging blood flow inside the brain, yields a very clear picture; however, only the very small area in direct physical contact with the probe can be inspected.
“The laser speckle technique allows us to do essentially the same thing as the Doppler, but over a larger area. It’s a full imaging approach rather than just a point sampling,” Dunn says. “We now have a full picture of the spatial distribution of blood flow, and we can get that dynamically in time.”
The medical implications of Dunn’s novel approach could be huge. For example, Dunn’s team is currently using the laser speckle technique to dynamically visualize the evolution of a stroke. What they’ve found may be the key to the next stage in stroke treatment.
Though the new technique has yet to reveal exactly what causes the spontaneous events that occur in the brain after a stroke, researchers have been able to identify several drug treatments that prevent them. By blocking the events, the actual progression of the stroke can be slowed.
Not only is laser speckle simpler and more effective than current technology, it’s cheaper too. Essentially, the laser speckle device is a small, low-powered diode laser—the same laser that’s used in most DVD players—plus a simple image detector (in this case a digital camera) and some imaging optics. “It’s one of the rare cases when the more effective technology is less expensive,” Dunn says.
A New Light in Cancer Research
Working adjacent to Dunn in the university’s Engineering-Science Building, Tunnell creates new devices for the early detection of skin cancer.
Tunnell’s specialty is optical spectroscopy and spectral diagnosis—he too studies the interaction of light with live tissue to gain useful medical information. In his words, “Spectroscopy measures the details of the color of light very specifically. The light shines on the tissue and interacts in a certain way, then comes back. Those interactions adjust the color of light in a way that allows you to measure certain properties of the tissue.”
Tunnell and his group are designing a device that uses light to examine a patient’s skin and determine whether the cells under scrutiny risk developing cancer. The device uses a small probe, about the size and shape of a pen, which emits weak pulses of light on the tissue, then collects the light back for analysis. That re-emitted light tells a story about the morphology and biochemical features of the tissue, and diagnosis follows.
The device, tentatively called a “clinical spectrometer,” (although Tunnell is open to suggestions for another name) is breaking ground in skin cancer detection. “There are no current clinical devices like this for detecting skin cancers that I’m aware of,” Tunnell says.
Dr. James Tunnell uses light to detect cancer of the skin.
Photo by Marsha Miller
According to Tunnell, his interest in skin cancer is partly fueled by the heat of his home state. “In Texas, skin cancer prevalence is increasing astronomically, not to mention that I have the skin type that’s prone to it.” Tunnell spent a good deal of time in the sun as a child in Corpus Christi while observing research performed by his father, a marine biologist and Fulbright scholar.
Tunnell often tagged along on field trips to study coral reefs and collect samples of marine life. “I met a lot of grad students that way, and became familiar with the research process,” he says. “I don’t know if I would have ended up in academia otherwise.”
Pioneers’ Paths to Biomedical Engineering
Tunnell’s path to the vanguard of his field was remarkably circuitous. He entered his freshman year of college at Baylor University in 1993 as a music major. But after transferring to The University of Texas at Austin the next year and attempting to double major in both electrical engineering and music, he found that trying to stay on top of his new coursework while practicing violin for several hours a day was pushing a bit too hard. He elected to exchange his strings for his science.
“Since I was young I’ve been interested in science and engineering. I thought I’d try out music for a year,” he remembers. “But given my limited musical talent, I thought I could make a bigger impact in engineering than I would be able to do in music.”
Dunn, on the other hand, had his heart set on science from the get-go; his journey was a straight shot. After earning his bachelor’s degree in physics from Bates College in Maine, he moved on to receive his master’s degree in electrical engineering from Northeastern University in Boston. There, he developed a keen interest in biomedical applications—optics in particular. He knew that many of the leaders of the biomedical optics field, which was fairly young at the time, performed their research at The University of Texas at Austin. Accordingly, Dunn opted to move south to Texas to work on his doctorate among front-line biomedical engineering researchers such as Drs. Rebecca Richards-Kortum and A.J. Welch.
While working at Massachusetts General Hospital, after completing his post-doctoral assignment at the University of California at Irvine, Dunn honed in on his area of expertise. “In Massachusetts, I started interacting with neurologists, both clinical and research,” Dunn says. “We became interested in combining some of the engineering approaches for imaging the brain. It was actually in collaboration with a neurology lab in Boston where we developed this technique for imaging blood flow, laser speckle.”
Passing the Torch
The Biomedical Engineering Department is actually an inter-institutional network comprised of three bodies: The University of Texas M.D. Anderson Cancer Center in Houston, the UT Health Science Center in Houston and the Cockrell School of Engineering at The University of Texas at Austin. Those three institutions working together form the department, essentially expanding the faculty from the 20 or so members at The University of Texas at Austin to include faculty in Houston who are closer to the clinical side. So when engineers such as Dunn and Tunnell are looking to advance their technologies from the drawing board to the doctor’s office, the partnership of the three institutions smoothes the process.
“For example, if we have a cool new imaging device that we built and want to move it to the next level, we’re linked to the medical school,” Tunnell explains. “We can take our device down to the medical school where faculty and laboratories help us test the device, better translate it from the bench, and eventually commercialize it.”
That translation is more or less the crux of the university’s Biomedical Engineering Department. It seeks to cultivate engineers fluent in both the mechanical side and the organic side of health care technology—people who ease communication between the physicists and the physicians.
“Learning how to work and interact with people on the biology side—conveying technical information to the biologists and in turn understanding how the biological information feeds back into the technology—has always been important to me,” Dunn says. “It definitely takes time and practice to learn how to do that, and it’s an important perspective I always try to impress upon the students.”
Tunnell upholds the importance of education’s place in the development of biotechnology. “If I wanted to just produce technology, I would have gone to industry or to a national lab or to something that didn’t have students,” he affirms. “We produce technology, but I think at the end of the day the most important thing we do is teach the next generation of engineers.”
We may be a few generations away from the ability to heal bones with a laser scanner or to generate organs with a matter replicator a la Star Trek. But with teams like those of Tunnell and Dunn pushing biotechnology to the next step, we’ll at least be assured that our doctors are armed with more information than ever before—information gathered at the speed of light.
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