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Did you hear the news on ultrasound?

Created date

May 30th, 2009

Even though it has an echo, you won t hear it. Without making any sound you can hear, an ultrasound instrument sends pulses of sound through your skin to meet your muscles, organs, and other soft tissues. The pulses bounce back and create an image. Ernest Feleppa, Ph.D., research director of the Lizzi Center for Biomedical Engineering at the Riverside Research Institute in New York, describes how ultrasound imaging resembles what you see with weather radar on television. An image is created based on the combination of echo pulses returning from every direction. Typically, ultrasound images appear in tones of black and white. Some parts of the body reflect the sound more strongly and become brighter points in the image, creating contrast. "If everything reflected at the same echo strength, the image would just be a uniform gray," Feleppa says. Long used as one of many tools in a doctor s kit, ultrasound allows a look at an unborn child, blood flow through the vessels, bone loss, eye disease, and the size and shape of the heart. But it can also be used to see things that shouldn t be there. Seeing suspicious areas "In many cases, ultrasound enables you to see cysts and lesions like cancer. Those entities reflect the ultrasound differently than their surroundings," Feleppa says. But a diagnosis isn t usually based on an ultrasound image alone. "You can use ultrasound to see if something is likely to be a cancerous lesion and warrant a biopsy," Feleppa adds. "Then you can guide the biopsy using ultrasound particularly if it s a needle biopsy." In addition to providing pictures, ultrasound waves can make changes to your body. Larry Crum, Ph.D., a principal physicist and research professor at the Center for Industrial and Medical Ultrasound at the University of Washington, explains: "Ultrasound technologies are used not only for imaging like you see with an unborn child, but they are also used for therapy. The difference is how powerful the ultrasound is." Therapeutic ultrasound, also called high intensity focused ultrasound or more simply, focused ultrasound uses heat and vibration to kill tissue. "Diagnostic ultrasound [for imaging] doesn t damage anything," Crum says. "But therapeutic ultrasound does damage cells. It s a new development of medical ultrasound that has a promising future. You can perform totally bloodless surgery." ' Wiping out tumors ' Crum compares focused ultrasound to a magnifying glass that focuses light from the sun to a small point. Focused ultrasound works in the same way. "You can focus ultrasound, and it gets so hot that it can actually destroy tissue inside your body without ever making an incision," Crum says. "In some cases, nothing more than some faint tickling is felt; in others, general anesthesia is required." According to the Focused Ultrasound Surgery Foundation, which was founded to shorten the time it takes for focused ultrasound to go from technology development to patient treatment, focused ultrasound was initially evaluated for Parkinson s disease and other brain-related disorders because it provided an approach without invasive surgery. ' In a hospital near you? ' To date, one medical device has been approved by the U.S. Food and Drug Administration (FDA) and is being actively used for high intensity focused ultrasound in the U.S. Used in combination with magnetic resonance imaging MRI, a radiology technique to produce images of internal tissue it targets uterine fibroids, which are benign tumors of the uterus. "The first FDA-approved device was developed by Sonocare Corporation in the 1980s to treat glaucoma, but the company was unable to compete with laser devices. The same instrument was used experimentally to treat intraocular [in the eye] tumors and cardiac diseases, but these applications were never submitted for FDA approval," says Feleppa. But now researchers are working on additional applications, including breast cancer and pancreatic cancer. Plus, clinical trials are underway for FDA approval to treat benign prostatic hyperplasia (enlarged prostate) and prostate cancer. "There are many promising new trends for medical ultrasound," says Crum. "For people who can t stand surgery, this is noninvasive, with no penetration of the skin. But there are such good results using invasive surgeries for cancer tumors that new technologies have to be proven before they become a substitute," he says. ' Helping deliver drugs ' Feleppa describes the newest development on the horizon. "The latest area of ultrasound combines focused ultrasound with tiny bubbles or particles with drugs attached to treat a disease. As the particles circulate throughout the body, you can destroy them using focused ultrasound at the site where the drug needs to be released." As a form of targeted drug delivery, it could direct antibiotics, chemotherapy agents, genes, or growth factors in high concentrations specifically to the tissue where they are needed. Studies are also underway for using focused ultrasound to help deliver drugs to the eyes and to the brain. Listen closely and you just might hear more about ultrasound research in the near future.