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December 2012 Issue

Lihong Wang, PhD: Fulfilling a Dream of Impacting Patient Care

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Lihong Wang, PhD

Lihong Wang, PhD,

the Gene K. Beare Distinguished Professor of Biomedical Engineering at Washington University in St. Louis, changed his area of emphasis from electrical engineering to biomedical engineering because he dreamed about making a difference in patients’ lives.

“Both are exciting areas, but biomedical engineering presents more opportunities to enhance patient care within shorter periods of time,” he says. 

Professor Wang is on the threshold of fulfilling his dream as he heads the research team developing a new imaging technique called photoacoustic tomography (PAT). In the near future, PAT has the potential to surpass MRI and CT scans for safely detecting early-stage cancers and determining and monitoring treatment.

“PAT combines light and sound to produce a high-contrast, high-resolution image,” explains Professor Wang, a research member at the Alvin J. Siteman Cancer Center. “Light alone doesn’t allow us to see deeply into our tissues because it doesn’t go on a straight path as X-ray does. Absorbed light generates a sound signal.”

Professor Wang and his associates added a laser light delivery device (light) to an ultrasound imaging device (sound). The resulting instrument first targets tissue with a light. As the light is absorbed, the tissue expands, producing a sound pressure wave that is picked up by the ultrasound device. 

One of the first PAT applications being tested is its use as a nonsurgical alternative for staging breast cancer through needle biopsy of the lymph nodes. Currently, determining the stage of a breast cancer—how advanced it is—is achieved with a biopsy checking for the presence of cancer cells in the sentinel lymph node—the lymph node closest to the cancer, which for breast cancer is in the axilla or underarm. A surgeon first injects a blue dye or radioactive substance near the cancer; the injected substance is carried to the nearest lymph node, which the surgeon removes with a needle to examine for cancer. 

“For 90 percent of breast cancer patients, the good news is that the biopsy produces benign results,” says Professor Wang. “However, the surgery can result in a complication called lymphedema. This is a lifelong disorder that causes fluid retention, pain and swelling in the arm. There is no cure for lymphedema.”

If proven effective, PAT could help eliminate lymphedema. 

“We are working with Siteman’s breast cancer specialists and radiologists to identify patients for inclusion in testing PAT’s nonsurgical light and sound technology to identify the sentinel lymph nodes,” says Professor Wang. “Once the node is identified, the surgeon can guide a needle to the node and remove cells to test them for the presence of cancer.”

Another area of cooperative study is under way with Siteman dermatologists for diagnosing and treating melanoma, the deadliest type of skin cancer. PAT has the potential for measuring a melanoma’s parameters, which will help surgeons determine how much surrounding tissue should be targeted to ensure the entire tumor is removed. In addition, the deeper a melanoma grows into the skin, the greater the risk for the cancer spreading to the lymph nodes. As with breast cancer, PAT could prove effective for obtaining nonsurgical lymph node biopsies.

“PAT has the potential for a whole range of clinical applications, among them brain imaging, detecting prostate and colon cancer, and monitoring blood oxygenation,” says Professor Wang. “It goes beyond X-rays in that it can provide information on how an organ or system is functioning, rather than just its structure.” 

Professor Wang and his research team can measure their success in advancing PAT research through their published papers—the group has the most-cited papers in the field of photoacoustic tomography—and their research budget—more than $38 million in grants from the National Institutes of Health (NIH).

But even those significant resources don’t cover Professor Wang’s wish list for research.

“Our NIH funding is granted based on very specific parameters we’ve laid out for each particular research project,” he says. “Funding is scarce for the high-risk, high-payoff ideas that could fundamentally solve some of the questions that remain regarding PAT’s potential. Discretionary funds donated to our laboratory from individuals or other private sources could be vital to this type of investigation.”

“This type of research takes a tremendous amount of support because of its experimental nature. Our 40-person team is the largest in the world and includes research faculty, postdoctoral researchers, research associates and students,” says Professor Wang. “It takes a great deal of funding to support the people involved in this work as well as the experimental facilities needed.”

For now, Professor Wang is seeing his dream of helping patients come true. “As a student, I knew I wanted to work hard and be a first-rate scientist,” he says. “I didn’t know this was the direction I would go in, but life has surprises sometimes. I can’t think of anything more rewarding than the work I do every day.”