Radiotracers Bring New Views for Breast Imaging

Two newer breast imaging techniques will help doctors diagnose and stage breast cancer, but neither technique will replace standard mammography for the detection of breast cancer.

Results from both studies were presented at the Radiological Society of North America meeting.

Both tests - breast-specific gamma imaging (BSGI) and positron emission mammography (PEM) - rely on the use of radiotracers to detect cancer cells.

The tracer used in BSGI has a positive charge. Cancer cells have a negative charge, so the tracer diffuses around the cancer cells, highlighting them in the process.

The tracer used in PEM contains glucose, which is used by cells for energy. Since cancer cells use more energy, they take up more of the tracer and are highlighted on the image.

"I think it's exciting that we're moving more to functional imaging," says Dr. Patrick Borgen, director of the Brooklyn Breast Cancer Program.

But, he adds, "Mammography is the mainstay of breast cancer screening, and neither of these tests is in a position to replace mammography as the cornerstone of cancer detection.”

Tests as Good as or Better than MRI

Dr. Borgen, who was not involved in either study, says the new tests offer additional ways to diagnose and understand breast cancer.

In one study, 208 women with breast cancer underwent PEM to assess whether or not this imaging technique was affected by breast density or by a woman's hormonal status.

The PEM scanner, like a mammogram scanner, immobilizes the breast but does not compress it, explains study author, Dr. Kathy Schilling, of the Boca Raton Community Hospital.

Cancer was accurately detected in 100 percent of fatty breasts, 93 percent of dense breasts and 85 percent of extremely dense breasts.

In addition, it was accurate for 93 percent of women regardless of whether or not they had used hormone replacement therapy, 90 percent of pre-menopausal women, and 94 percent of postmenopausal women.

Dr. Schilling says these results are similar to, or better than, breast MRI tests.

"PEM is an adjunctive tool, and it will probably be used as breast MRI has been used," says Dr. Schilling, who adds, "MRI causes so many more false positives and unnecessary biopsies."

Tests Not Widely Available Yet

The second study, which was led by Dr. Rachel Brem, from George Washington University Medical Center, reviewed data from 159 women who were found to have a suspicious lesion after mammography.

The women then underwent BSGI scanning, which uses mild compression to capture the images from the tracer.

The researchers found that BSGI located an additional suspicious lesion in 29 percent of the women. Of these, another third were found to be cancerous.

"The data suggest that BSGI allows for the diagnosis of more and earlier breast cancers," says Dr. Brem.

Neither of the tests is widely available yet, and Dr. Borgen notes that currently BSGI is much less expensive than PEM. 

Authors from both studies are board members of the companies that make the new imaging machines.

Always consult your physician for more information.