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Tumors in Hiding Beware: This Radiologist Will Find You Almost Anywhere

Pet Column for the week of June 1, 2009

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Office of Public Engagement
2001 S. Lincoln Ave.
Urbana, Illinois 61802
Phone: 217/333-2907
Ashley Mitek
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Source - Dr. Robert O'Brien
Detecting liver cancer in an old dog is not an easy task. To begin, many old dogs have what is called nodular hyperplasia. Benign masses grow on their liver, rarely causing complications. However, these friendly masses cannot be differentiated from malignant tumors without a biopsy, an invasive procedure to remove cells from the body for further tests.

That's where Dr. Robert O'Brien comes in. He is a professor at the University of Illinois College of Veterinary Medicine and is one of approximately 325 board certified veterinary radiologists in the country. He is pioneering a new way to diagnose liver tumors in dogs with the use of ultrasound and special contrast agents.

"We are one of about half a dozen places in the world that are using contrast-enhanced ultrasound to characterize liver lesions," says Dr. O'Brien. His breakthrough research over the past few years has proven that some malignant tumors can be identified in a matter of seconds using ultrasound. He explains that it's as simple as "injecting a contrast agent and watching the blood flow to the area."

The ability of doctors and veterinarians alike to use ultrasound to view structures within the body has been around for nearly half a century. It is most commonly used to visualize a fetus in utero because it is extremely safe and radiation free.

By using ultrasonic sound, the machine generates waves that bounce off an object and return a signal to the transducer to produce an image. While an inexperienced eye may look at an ultrasound screen and see blobs of grey, white, and black, a radiologist sees organs, vessels, tendons, and perhaps a tumor in hiding.

Unlike humans, dogs and cats can hear ultrasonic sound. Some animals, such as rodents and bats even make it. But diagnostic ultrasound machines works at a frequency 1,000 times above the threshold of our pets' hearing capabilities, so your pooch need not wear earplugs for the procedure.

The best part about Dr. O'Brien's ultrasound technique is, "it is a minimally invasive test with basically no morbidity associated with it," he notes. The contrast agents that he uses are the same that are used in human medicine and are extremely safe, even at high levels.

While it sounds much more high-tech, the contrast agents are really just microscopic bubbles. They are filled with gas and surrounded by an outer casing. When injected into an IV catheter they show up on the ultrasound screen and allow radiologists to differentiate tissue from blood vessels.

Although this procedure is most commonly used to classify liver masses, it also can detect disease in other organs such as the spleen, kidney, and pancreas. The benefits of contrast ultrasound aren't just for our four-legged friends either. It has been used in human medicine for characterizing several different types of cancers, including staging of breast cancer for the past decade.

Due to the novel use of contrast ultrasound in veterinary medicine, the procedure is currently only available in a few select veterinary hospitals. However, the available research is very promising and in the near future it may become the preferred method of detecting certain tumors.