A new approach to mammography, developed by researchers at Massachusetts General Hospital (MGH), holds the potential for greatly improving the detection of breast lesions and the ability to predict whether they are benign or malignant.

In a presentation at the scientific assembly of the Radiological Society of North America (RSNA), Elizabeth Rafferty, MD, of the MGH Breast Imaging Service described initial results of a study comparing the new technique, called digital tomosynthesis, to standard mammography. Among the new technique's advantages, she explains, is a significant reduction in false positive test results.

"The overlap of breast structures presents a major challenge for radiologists, both because these tissues can hide cancers and because they produce shadows which mimic a lesion on conventional mammography," Rafferty says. "These false positive studies account for almost 25 percent of the instances when women are recalled for additional imaging from their screening mammograms. By eliminating this structure overlap, tomosynthesis prevents virtually all of these unnecessary callbacks, along with the anxiety they create."

Tomosynthesis differs from standard mammography in the way a CT scan differs from a standard X-ray procedure. In tomosynthesis, the X-ray tube moves in a 50-degree arc around the breast while 11 low-dose images are taken during a 7-second examination. A computer then assembles the information to provide high-resolution cross-section and three-dimensional images that can be reviewed by the radiologist at a computer workstation.

"Tomosynthesis takes digital mammography to the next level," adds Daniel Kopans, MD, MGH director of breast imaging and a coauthor of Rafferty's presentation. "It is a modification of a standard digital mammography unit. The breast is held the same way, but women will be happy to learn that the test requires only one compression of each breast rather than the two currently required by standard mammography." Kopans is one of the inventors of the digital tomosynthesis system, which has been patented by the MGH.

Rafferty's report covers data from the first 100 women to volunteer for tomosynthesis in addition to standard mammography at MGH. Her data indicates that tomosynthesis makes lesions easier for the radiologist to see and also makes visible some lesions not detectable by conventional procedures. The radiologists who reviewed both standard mammograms and tomosynthsis images for the study reported being significantly more confident in determining the malignancy of lesions with tomosynthesis, Rafferty said.

SOURCES:
Scientific Assembly of the Radiological Society of North America (http://www.rsna.org)
Massachusetts General Hospital (http://www.mgh.harvard.edu)