Despite lacking FDA approval, breast digital tomosynthesis is already making waves in the breast imaging community. A recent study from the University of Pittsburgh Medical Center published in the American Journal of Roentgenology shows combining breast digital tomosynthesis with full-field digital mammography lowers recall rates. The modality could also be especially helpful in imaging women with dense breasts, according to several radiologists.

The FDA is still testing and collecting data on digital tomosynthesis, so only a handful of sites in the U.S. are using the modality. Siemens, Hologic, and GE have installed their machines at institutions around the country to gather the information they will need to gain FDA approval. Digital tomosynthesis has already been approved for use in Europe.

Even though breast digital tomosynthesis can be found only in scattered places in the U.S., mammographers are already buzzing about the new approach because it enables 3D reconstruction. This capability allows cross-sectional visualization of breast tissue and reduces the difficulty caused by superposition, the overlapping of tissue when viewed in projection mammograms.

With breast digital tomosynthesis, the breast is compressed in standard fashion while an x-ray tube arcs over the breast, capturing images at every angle. Typically, 10 to 20 exposures are made during a scan of five seconds or less. The individual images are projections through the breast at different angles that are reconstructed into slices.

Besides reducing recall rates, as the AJR study showed it can (AJR 2009;193[2]:586-591), other potential advantages of the modality include improving cancer detection in women with dense breast tissue and reducing the number of negative biopsies.

Combining digital breast tomosynthesis with full-field digital mammography reduced recalls by 30% in the University of Pittsburgh study. Use of digital breast tomosynthesis alone reduced recalls by 10%, although the researchers said the observed decrease was not statistically significant.

The studies were read by eight radiologists, all of whom performed at a higher sensitivity (93%) and specificity (64%) when viewing and rating the digital tomosynthesis studies of the 125 subjects. Using full-field digital mammography alone they had substantially lower sensitivity (88%) and specificity (60%).

Readers require extensive training in digital breast tomosynthesis to recognize abnormalities as well as widely varying normal tissue that can cause negative findings.