An unrelated pilot study presented at a gathering in December has found that magnetic resonance imaging (MRI) alternated with mammography at six-month intervals can detect breast cancers not identified by mammography alone.

The study was conducted by a research team from The University of Texas M. D. Anderson Cancer Center, in Houston.

MRI is known to be more sensitive in detecting breast cancers than mammography, with 71 percent to 100 percent accuracy, compared with 16 percent to 40 percent accuracy for mammography. As a result, annual breast cancer screening for high-risk women now typically includes MRI along with mammography and a clinical breast exam.

"In the high-risk population, the recent standard of practice is to perform mammography and MRI every year," says Dr. Huong Le-Petross, assistant professor of diagnostic radiology at M. D. Anderson and the study's first author. "What we started to do at M. D. Anderson was to see if we could do mammography and then six months later do a breast MRI exam, followed six months later with a mammogram exam, and then six months after that with a breast MRI. That way the women would receive an imaging modality screening every six months."

The alternating MRI and mammography screening program detected nine cancers among 86 high-risk women

Le-Petross says, "We found that MRI picked up the majority of cancers, while mammography picked up only three out of the nine. With five of the eight cancers detected by MRI, the mammogram from six months earlier was either normal or suggested benign findings.

"The global picture is that MRI can pick up cancers that mammography cannot," Le-Petross says. "This would suggest that in this population it is more beneficial for the patient to have screening MRI so that we can pick up small lesions before a mammogram can detect them."

One important unanswered question is whether an alternating MRI and mammography screening program will save lives.