Imaging is everything
Biomedical engineers combat diseases with procedures that are painless to patients
When Dr. Rene Laennec made the house call in September 1816, he did not plan to leave with a device that would revolutionize the way doctors treat patients. Instead, he saw a challenge—how to hear the heartbeat of a woman whose “great degree of fatness” muffled its sound.
Remembering a bit of physics, he rolled up a newspaper, put one end to the heart and the other end to his ear, and heard a heart beat more distinctly than he ever had before. He immediately realized the potential for the makeshift design and later created the first stethoscope (literally, “chest scope”), which he made from wood.
His invention, like so many in biomedical engineering, came about from necessity, in this case a need to hear the body’s most basic function, the beating of the heart. Today’s biomedical engineers work with the same goal—to bring better health to everyone by finding solutions to challenges facing the medical community.
At The University of Texas at Arlington, three professors are using optical imaging techniques to develop non-invasive, painless methods of diagnosing and treating patients with serious illnesses.
For Hanli Liu, associate professor of bioengineering, the challenge is finding the best way to diagnose and treat brain tumors, which occur in about 14 people per 100,000 in the United States. Twenty-three percent of the tumors are malignant.
Dr. Liu thinks she has a solution in the infrared optical imager. She began researching this imaging method in 1997 through a grant from the Whitaker Foundation, an organization that supports research in biomedical engineering. Her latest grant from the National Cancer Institute provides more than $1 million over four years to develop the imager and then perform animal testing to determine the best treatment options for patients with shallow brain tumors.
Although targeted at the region of the brain where the tumor exists, standard radiation therapy can damage normal cells surrounding the tumor. Liu’s portable, non-invasive imager works with a new technology, intensity-modulated radiation therapy (IMRT), which shoots tiny beams of radiation into the tumor focused at a single point.
IMRT decreases the likelihood of damaging healthy cells. As the radiation is being administered, the imager, attached to the patient’s skull near the tumor site, uses fiber optics with near-infrared light to take photos and document the radiation’s effects.
“We will be able to demonstrate immediately how the tumor is responding to the treatment when the imager is fully developed and utilized in actual radiation studies,” said Liu, whose research study has entered its second year.
The optical near-infrared imaging prototype should be complete by the end of 2005. The next phase, animal testing, will be done in collaboration with doctors from UT Southwestern Medical Center at Dallas and from Baylor Radiosurgery Center at Dallas.
In that phase, the imager will monitor the radiation treatment of rats implanted with human brain tumors. The data should help researchers create treatment protocols by determining the optimum number of radiation beams, beam size and the length of beam exposure. The researchers will also gauge the effect of radiation treatment when paired with therapeutic interventions such as oxygen therapy.
Liu’s research partners on the project include UT Arlington bioengineering Professor Khosrow Behbehani and mechanical engineering Professor Bo Ping Wang, and Cole Giller, medical director at Baylor Radiosurgery Center.
Shedding light on diabetes
Bioengineering Assistant Professor Karel Zuzak’s challenge is to develop imaging technology that will improve the treatment of diabetes. Diabetic retinopathy—a decline in blood circulation to the retina—causes 12,000-24,000 cases of blindness each year, while lower limb necrosis is blamed for 60-80 percent of amputations among diabetic patients. Early detection is the key to preventing these and other long-term complications.
Dr. Zuzak’s Reflectance Hyperspectral Imaging System uses visible light to show oxygen saturation in the body. The imager shines a light on the body part, usually the hand, foot or eye, and then translates the reflected light into colors that indicate blood oxygenation levels.
Zuzak developed the imaging method in 1999 while at the National Institutes of Health. After completing the system, he applied the imager to clinical studies. The Army was interested in the effect of inhaling nitric oxide. Nitric oxide relaxes smooth muscles surrounding blood vessels, which can then transport blood more efficiently.
In Zuzak’s study, patients were intravenously given L-NMMA, a chemical that prevents the body from using nitric oxide. The chemical constricts blood vessels and reduces circulation. As hypothesized, the resulting body images showed a decrease in the amount of oxygen being carried by the blood.
Since arriving at UT Arlington in 2004, Zuzak has built a second prototype of the Reflectance Hyperspectral Imaging System and is refining the design to evaluate other molecules in the blood. His continued research will examine the effects of diabetes on vasculature in the lower extremities and eyes.
One study will determine if blood flow in diabetics decreases, causing lower limb necrosis or tissue death. Diabetics tend to lose feeling in their feet, which can lead to infection, gangrene and amputation.
“There is speculation that the problem is not vascular, but I don’t believe that,” Zuzak said. “If we can make that determination, we can figure out ways to treat the problem early, with the hope of preventing amputation.”
The study will monitor the lower limbs of diabetics over time to determine if infections and the loss of feeling are vascular in nature.
A second study will focus on the changing vasculature in the eyes. In some diabetics, these changes can lead to blindness.
“If the imager can detect these changes early, clinicians can initiate treatment early,” Zuzak said. “Using the imager to monitor changes early on can delay or prevent blindness.”
Most of Zuzak’s research is funded by the UT Arlington Office of the Provost, the Office of the Dean of Engineering and the Department of Bioengineering. He also has received significant assistance from the University’s Research Enhancement Program.
Illuminate to eliminate cancer
The challenge for bioengineering Assistant Professor Digant Davé is early cancer detection. According to the American Cancer Society, each year more than 1.3 million cancer cases are diagnosed and more than 570,000 people die from the disease. Treatment tends to be most successful when the cancer is found early, while it is still small and less likely to have spread.
Dr. Davé’s solution is his multimodality imaging platform, which performs an “optical biopsy” on high-risk patients. The instrument conducts three types of imaging analysis at the same time:
- Optical coherence tomography (OCT), which creates an image of tissue by shining light through it; the light reflects back in a manner similar to ultrasound. The image shows differences in the tissue, such as malignancy in cancer patients, through a morphological signature.
- Multiphoton microscopy, which provides three-dimensional images of living cells by looking at the cells’ fluorescence. This is especially beneficial in seeing the molecular signature within the cells, which are different in cancer patients.
- Bright field microscopy, the standard imaging method used in high school biology classes and by doctors using an endoscope. It serves as a guide to help doctors understand what they are seeing within the body.
“Each modality offers unique data about the patient,” Davé said. “By using all three techniques simultaneously, we hope to create a database of features that differentiate normal cells from cancer cells in the tissue.”
A two-year National Institutes of Health grant provides funding to build and test the imaging platform. Davé is building the platform and will begin testing later this year. During testing, he will check the molecular, cellular and subcellular levels of cancerous and noncancerous cells for distinguishing signatures; the findings could then be used in a clinical setting to indicate early stages of cancer.
Eventually, Davé hopes to build a fiber-based imaging platform that combines multiphoton microscopy with OCT and can be inserted into the body with an endoscope. The endoscope would move the imaging platform to the suspected cancerous area. By finding the cancers earlier, doctors can begin treatment more quickly and increase the likelihood for successful patient treatment and survival.
— Becky Purvis