Bioengineering graduate student Xinliang Zheng demonstrates the high-intensity focused ultrasound (HIFU) device.
The HIFU device emits large amounts of ultrasound into a concentrated spot, about the size of a grain of rice. This technology can help stop internal bleeding and cause damage to tumors without being invasive.
Graduate student Xinliang Zheng turns on the power amplifier that supplies energy to the HIFU transducer.
Imagine it’s the year 2080. Walking into the emergency room conjures up images from the Star Trek television series. Compact devices, reminiscent of Star Trek’s tricorders, complement an array of high-tech imaging monitors. No knives or scalpels are in sight.
When it comes to lung puncture repair, this image may not be far off — some researchers think its future could rest in the hands of ultrasound technology.
Tucked away on the outskirts of campus, researchers are carrying out cutting-edge research — quite literally. The Department of Bioengineering and the Applied Physics Laboratory at the UW are international leaders in research on high-intensity focused ultrasound (HIFU).
HIFU takes acoustic energy and focuses it to a precise point. The focused energy heats up enough to sear tissue and seal a wound. The device used for sealing wounds is called an HIFU transducer. The device itself is small with a concave head that allows it to focus acoustic energy.
“Think of the magnifying glass that you used as a kid to focus heat towards a specific point to burn paper or insects,” said Gregory Jurkovich, chief of trauma at Harborview Medical Center and a professor of surgery at the UW. “You can basically do the same thing with ultrasound. You take high frequency ultrasound waves and focus it down to a point. That point can generate heat.”
The heat generated from the HIFU reaches 40 degrees Celsius in one second and has the ability to generate heat above 100 C. The focused heat from HIFU is precise to about 1 centimeter by 1 millimeter, approximately the size of a grain of rice, said Xinliang Zheng, a Ph.D. candidate working on HIFU research in the bioengineering department.
Before HIFU is used to sear the wound, another device must scan the site to identify the wound. This scanning device maps out an image of the area in the same way ultrasound is used to view a fetus in a mother’s womb.
“You’re using the same ultrasound technology to image and treat,” said Joo Ha Hwang, an assistant professor of gastroenterology.
This dual use of ultrasound technology is called image-guided therapy. But while both scanning and treating utilize ultrasound, the difference between their intensities is huge.
The energy used for ultrasound imaging is 0.1 watts per square centimeter, whereas the energy used in HIFU can be upward of 1,000 watts per square centimeter, depending on its application, Zheng said.
The idea of using ultrasound to scan an internal wound is similar to Star Trek’s tricorder device, which was used to identify internal injuries.
“You look at Star Trek and you look at an idealized universe,” said junior Aaron Heyamoto, a pre-engineering student and Star Trek fan.
He said that Star Trek does a good job of forecasting the vision of a futuristic but realistic universe. The HIFU device is evidence of this.
In June 2007, Shahram Vaezy, an associate professor of bioengineering, and a team of physicists, bioengineers and surgeons published the first research study on HIFU application to punctured lungs. The study was published in The Journal of Trauma as a result of about 10 years of research. It included 11 pigs and 70 incisions sealed using HIFU. According to the published results, 95 percent of the incisions were sealed within two minutes of HIFU application.
The advantage of using HIFU technology to seal punctured lungs is that it allows for noninvasive surgery. The procedure for patients coming into the hospital with punctured lungs typically requires applying pressure and suctioning the air and blood out to allow for the wound to heal. If that doesn’t work, doctors slice open the chest and seal the puncture with staples.
“What’s neat about [HIFU] is that you can conceivably do it outside the body,” Jurkovich said.
He explained that HIFU’s application to lung punctures is part of a medical trend to treat without violating the body.
“That would put me out of a job,” Jurkovich joked.
In addition, HIFU would reduce the cost of health care bills. The absence of surgery and the safety of ultrasound technology allows for quick recovery.
“Patients wouldn’t need to stay in the hospital. It would reduce the cost for the patient and the hospital,” Zheng said.
However, the energy-generating machine is large. Researchers are working on reducing its size for convenience.
The application of HIFU expands far beyond sealing punctured lungs. It can target wounds in the liver, kidneys, pancreas and even blood vessels. Worldwide, most research on HIFU technology is exploring its application in killing cancerous tumor cells.
HIFU therapy is used for destroying cancerous tissues, and it is practiced in many countries outside the United States. The most common usage is the treatment of prostate cancer.
With Food and Drug Administration regulations and the long process of clinical trials, the United States does not yet offer HIFU as a line of treatment for malignant tumors. However, it is popular in China and there are also clinics in Canada, the Caribbean and South Africa.
Jurkovich said that the Harborview Trauma Center receives about one punctured lung patient a day.
Despite rapid advancement in HIFU technology in the past few decades, research is still in its early stages.
“I would say within 10 to 15 years we’ll have a better idea of the application of HIFU. … More research needs to be done to find the best applications,” Hwang said.
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