A new dimension for breast exams

By Lauran Neergaard

The Associated Press

WASHINGTON

Remember peeking through a View-Master? Scientists are using the same concept behind the classic children's toy to try to see mammograms in 3-D.

The goal: a better way to check for breast cancer in women with breasts too dense for today's mammograms to give a clear picture.

Radiologists donning 3-D glasses isn't the only potential aid. The Mayo Clinic in Rochester, Minn., is testing a new kind of breast camera that might challenge the images of far pricier MRI exams now reserved for the most high-risk women, but at a fraction of the price.

Both technologies still are experimental. But the research is being watched closely because the need is so great: Half of women younger than 50 and a third of women older than 50 are estimated to have dense breasts.

In addition to the greater difficulty of viewing any brewing tumors, women with dense breasts have a higher risk of getting breast cancer, too.

Only a mammogram can tell whether a woman's breasts are made up of dense or easier-to-examine fatty tissue. But if a doctor warns a patient that she has dense breasts, there's little good advice on how to get a better cancer check today.

"It's a major issue in the field now, more and more, how to address the imaging needs of women with significant breast density," American Cancer Society screening specialist Robert Smith said. "We and women and everyone else is kind of left wondering what would be best under what circumstances."

"We can do better than we're doing," said Dr. Mary S. Newell, assistant breast-imaging chief at Emory University in Atlanta, who is testing the 3-D approach.

Mammograms are X-ray exams that hunt denser spots in normal breast tissue, shadows that might signal a tumor. Regular mammograms starting at age 40 help reduce deaths by finding tumors when they're smaller and more treatable.

They're far from perfect, however, and dense breasts may be the X-rays' biggest hurdle.

Some doctors already give women with dense breasts an ultrasound exam - the same sound-wave test used to view a developing fetus - in addition to a mammogram. A handful of studies have concluded that ultrasound improves cancer detection, but it remains controversial. Other women seek MRIs, which detect blood-flow changes that could signal cancer. But they're not recommended solely for dense breasts, partly because of their $1,000-plus price. Both options trigger a lot of false alarms by spotting suspicious areas that turn out to be fine.

Mammograms are two-dimensional, flat pictures of a surface that's simply not flat. When technicians literally smush women's breasts into the mammography unit, they're trying to spread the tissue out so less is hidden from the X-ray. "Stereo mammograms" allow radiologists to see those X-ray images in 3-D, so that a small spot on the bottom might not be hidden by normal tissue lying over it.

Humans have depth perception because each eye gets a slightly different view, allowing the brain to construct a

3-D view when it overlays the two, Newell said. That's the concept behind stereoscopes, gadgets that help people see pictures in 3-D like the old cartoons of a View-Master.

Stereo mammograms, being developed by BBN Technologies, work essentially the same way. Separate X-rays are taken at slightly different angles. Then radiologists wear glasses that make each eye see a separate image on special monitors. The brain "reads" that as a single, 3-D view.

In a soon-to-be-published study, Emory radiologists gave nearly 1,500 women at increased risk of breast cancer both a mammogram and a stereo mammogram. Different radiologists analyzed each test. When researchers put together the results, the stereo mammograms increased detection of cancer by 23 percent, Newell said, and decreased false alarms by 46 percent.