Experimental Imaging System Helps Detect Breast Cancer

THURSDAY June 26, 2008 -- Researchers have devised a new breast-imaging technology that appears to be as accurate as MRI scans but several times cheaper.

The technique, called molecular breast imaging (MBI), is still in the early stages of development, the scientists added.

"We envision MBI being useful for women who are not served well by mammography, those who have mammographically dense breast tissue, and those at increased risk for breast cancer," said study author Carrie Beth Hruska, a research fellow at the Mayo Clinic in Rochester, Minn. "We have been working on the technology for the last six years. However, there are a lot of technical challenges that have had to be overcome, so it's still in the very early stages for use in patients."

In fact, MBI is currently only used in the context of research studies.

Hruska was to present her findings Thursday at the Department of Defense "Era of Hope" Breast Cancer Meeting, in Baltimore.

Mammography is still the standard and most reliable screening test for breast cancer, and is likely to remain so for some time. But, mammography may be less effective in women who are at high risk for the disease or who have dense breasts (the two groups tend to overlap).

Last year, the American Cancer Society issued recommendations that women at high risk for breast cancer (such as those with the BRCA1 or BRCA2 gene mutation or a strong family history of the disease) have annual MRIs in addition to mammography.

MRIs have "high sensitivity," meaning they pick up a lot of unusual spots in the breast, but those spots aren't always malignant. And MRI screening is costly.

"MRI is very expensive, highly sensitive and not specific, so there are a number of false-positives," explained Dr. Jay Brooks, chairman of hematology/oncology at Ochsner Health System in Baton Rouge, La.

Hruska said, "The jury is still out as to whether to recommend MRIs for women with dense breasts."

MBI is based on an intravenous injection of a radio "tracer" that circulates throughout the body and is preferentially taken up by cells that are more active than normal, such as cancer cells.

"We can then see this tracer with a special gamma camera we call the MBI system," Hruska explained. "This camera basically detects the gamma rays that are emitted from the tracer and, if there is more tracer, that's where the cancer is located." MBI is not affected by breast density and costs four-to-six times less than an MRI exam in both breasts, Hruska added.

In 48 patients suspected of having breast cancer who had undergone both MBI and breast MRI within a 30-day period, both MBI and MRI picked up disease in 47 of the 48 patients. In the final patient, two cancers went undetected by MBI but were picked up by MRI.

In all, 54 cancers in 32 patients were diagnosed. MRI picked up 53 cancers in 31 patients (a sensitivity of 98 percent) while MBI found 51 cancers in 30 patients (a sensitivity of 94 percent). One cancer was not diagnosed by MRI, MBI, mammography or ultrasound.

"It's a very interesting abstract and presentation," Brooks said. "It was a small number of patients, but it definitely bears looking at. This would be an interesting adjunct and maybe something worth looking into in the future with larger numbers of patients."

A second study, this one presented at the annual meeting of the Society of Nuclear Medicine in New Orleans recently, found that a custom-built scanner combining both positron emission tomography (PET) and computed tomography (CT) technologies might enhance current breast-imaging abilities. The technology may one day help with more personalized treatment options and could help determine if therapies with certain drugs are actually working in specific patients, said the authors, from the University of California-Davis in Sacramento.

More information

Visit the American Cancer Society for more on early detection of breast cancer.

Posted: June 2008


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