Ultrasound Using Microbubble Contrast Agent Provides Way to Visualize Tumors

By MedImaging International staff writers
Posted on 10 Feb 2014

Whereas ultrasound provides a less expensive and radiation-free way to identify and track cancer in comparison to technologies such as X-rays, computed tomography (CT), and magnetic resonance imaging (MRI) scans, ultrasound has seen limited use in cancer treatment because of its clarity and resolution problems. Nevertheless, researchers have overcome these hurdles by combining ultrasound with a contrast agent composed of tiny bubbles that pair with an antibody that many cancer cells produce at higher levels than do normal cells.

By binding to the protein SFRP2, the microbubble contrast agent greatly improves the resolution and tumor-detecting ability of scans produced by ultrasound. In an article published January 29, 2014, in the journal PLOS ONE, University of North Carolina (UNC) Lineberger Comprehensive Cancer Center (Chapel Hill, NC, USA) members Nancy Klauber-Demore, MD, professor of surgery and Paul Dayton, PhD, professor of biomedical engineering, from the UNC at Chapel Hill School of Medicine (USA) were able to visualize lesions created by angiosarcoma, a malignant cancer that develops on the walls of blood vessels.

Image: SFRP2 targeted microbubbles bound specifically to vessels (stained green) within angiosarcoma (right). A control without the targeted microbubbles (left) (Photo courtesy of UNC Health Care).

“The SFRP2-moleculary targeted contrast agent showed specific visualization of the tumor vasculature,” said Dr. Klauber-DeMore. “In contrast, there was no visualization of normal blood vessels. This suggests that the contrast agent may help distinguish malignant from benign masses found on imaging.”

Dr. Klauber-DeMore’s lab was the first to discover that angiosarcoma cells produce an excess of SFRP2. Building on that discovery, her team focused on how to use the protein to better monitor the progress of the cancer within blood vessels. Using a mouse model, the researchers delivered the microbubble contrast agent by way of intravenous injection and tracked it using ultrasound.

Since SFRP2 is expressed in many cancers, including colon, breast, pancreas, ovarian, and kidney tumors, the technique could potentially be useful on a wide range of cancer types. Dr. Klauber-DeMore reported that her colleagues now want to determine how well the technique works with these other tumor types, as well as studying its effect on breast cancer.

The study’s findings have shown that the level of SFRP2 in tumors increases as tumors develop, so Dr. Klauber-DeMore’s team will in addition examine whether the technique can be used to monitor tumor growth. This would make it helpful in tracking patient response to chemotherapy. They will also investigate whether it can be used to identify and visualize very small tumors.

Because ultrasound is less expensive than commonly used imaging methods, such as MRI, the new technique could help lower costs to patients who need cancer treatment. Moreover, because ultrasound is more portable than other imaging technology, it may be useful in providing treatment in rural and low-resource areas across North Carolina and throughout the United States.

Related Links:
University of North Carolina Lineberger Comprehensive Cancer Center
University of North Carolina at Chapel Hill School of Medicine