National Cancer Institute NCI Cancer Bulletin: A Trusted Source for Cancer Research News
February 22, 2011 • Volume 8 / Number 4

FDA Update

FDA Approves First 3-D Device for Mammography

The Food and Drug Administration (FDA) has approved the first 3-dimensional (3-D) mammography device for both screening and diagnosing breast cancer. The device is called the Selenia Dimensions digital breast tomosynthesis system, or Dimensions 3-D, and is manufactured by Hologic, Inc., based in Bedford, MA.

The approval, as explained in an FDA news release, was based on results from two studies in which radiologists were able to improve their ability to distinguish cancers from noncancers by 7 percent using the 3-D system compared with conventional mammography systems.

A 2-D mammogram image on the left shows a possible lesion, but the tomosynthesis images reveal no lesion in the breast. In the 2-dimensional (2-D) image on the left, there is a potential lesion in the subareolar region of the breast. In the tomosynthesis images on the right, it is easy to see that there is no lesion present. One can pick out individual structures on the separate slices, which summate to form the potential lesion seen on the 2-D projection image. (Image courtesy of Hologic, Inc.)

With conventional 2-dimensional (2-D) mammograms, overlapping tissue in the breast can hide potentially malignant lesions and can cause benign areas to appear suspicious. The Dimensions 3-D system uses both 2-D and 3-D images, producing “a stack of thin high-resolution image slices intended to provide clear rendition of structures in the breast and their spatial relationship with the surrounding breast tissue,” explained a Hologic news release.

The FDA approval was based on a retrospective study presented to the FDA’s Medical Devices Advisory Committee (MDAC) in September 2010. Compared with a 2-D system for breast cancer screening, the use of the Dimensions 3-D system reduced the recall rate from 51.5 percent to 12.9 percent. In this analysis, a Breast Imaging Reporting and Data System (BI-RADS) score of 0 was used as the basis for calculating recall rates. A BI-RADS score of 0 means that a mammography study is not yet complete and further evaluation, perhaps additional mammography views or an ultrasound, is required to make a final assessment.

The MDAC unanimously voted in favor of approval. Because it uses both 2-D and 3-D images, the Dimensions 3-D system doubles the radiation dose that patients receive, the FDA noted. There is “uncertainty” around cancer risk estimates associated with radiation exposure; however, the cancer risk associated with radiation from the new system is 1.5 percent higher than the baseline risk, which is defined as no radiation exposure from mammography, and is less than 1 percent higher than the risk associated with 2-D mammography, according to the agency.

Under federal regulations, the FDA noted, all health care professionals must obtain 8 hours of training with a new mammography technology before they can perform procedures on patients.