New 3-D mammography system may improve
Developed at MGH, digital tomosynthesis
may better identify malignant lesions
BOSTON - December 10, 2002 - 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 earlier this month 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,
Richard Moore, head of MGH Breast Imaging Research, says, "We
can now see the tree in the forest. Digital tomosynthesis opens
up multiple new avenues of investigation into better ways to detect
and diagnose breast cancer early." Moore and physicist Tao
Wu, PhD, helped develop the tomosynthesis device and algorithms
for analyzing data and producing images.
Kopans and his team worked closely with representatives of General
Electric to produce a prototype digital tomosynthesis system under
a grant from the U.S. Department of Defense, and he is optimistic
that ongoing clinical trials at the MGH will soon lead to FDA approval.
"Tomosynthesis is going to revolutionize the way we look for
breast cancers," Kopans says. "We have only begun to realize
the potential of this technology."
The Massachusetts General Hospital, established in 1811, is the
original and largest teaching hospital of Harvard Medical School.
The MGH conducts the largest hospital-based research program in
the United States, with an annual research budget of almost $300
million and major research centers in AIDS, the neurosciences, cardiovascular
research, cancer, cutaneous biology, transplantation biology and
photomedicine. In 1994, the MGH joined with Brigham and Women's
Hospital to form Partners HealthCare System, an integrated health
care delivery system comprising the two academic medical centers,
specialty and community hospitals, a network of physician groups
and nonacute and home health services.
Media Contact: Susan
McGreevey , MGH Public Affairs
Physician Referral Service: 1-800-388-4644
Information about Clinical Trials