MRI for Breast Cancer Detection Enables Increased Specificity
March / April 2005
While mammography remains the standard for screening women
for breast cancer, scientific studies report high sensitivity
and improved detection using Magnetic Resonance Imaging (MRI)
to screen women who are at high risk for breast cancer. Particularly
noteworthy among these studies is a recent report (The
New England Journal of Medicine, Vol. 351, No. 5: 427-437) that
supports the notion that screening with both mammography
and MRI may be a better option for high-risk women than using
either one alone.
The two groups of women who benefit most from MRI are those
who already have cancer in one breast, and those who are
genetically predisposed, such as women whose mother or sister
had breast cancer before the age of 40, or women who carry
a BRCA1 or BRCA2 gene, according to Mitchell
D. Schnall, MD, PhD, associate chair of Research and Matthew J. Wilson
Professor of Radiology at the Hospital of the University
of Pennsylvania. “Knowing the extent of cancer within
a breast can impact a patient’s decision on the type
of breast conservation therapy chosen, which would mean the
difference between choosing a mastectomy and a lumpectomy,” says
Dr. Schnall.
Advancing Coil Technology
“In the early days, I concentrated on innovations in
MR hardware - particularly
coil technology because that’s what enables us to get
higher resolution images,” says Dr. Schnall. The coil
is the interface between the MR magnate net and the patient.
Another important innovation in which Dr. Schnall and his
team played a pivotal role was MRI systems that allow for
biopsy. “If you’re going to find occult cancer,
you have to confirm it,” he explains. “Penn has
been very active in the advances achieved in both hardware
and in pulse sequence development, which is essentially the
software that drives the machine,” he says.
Dr. Schnall continues to advance coil technology. “Our
aim is to see how far we can push spatial resolution—particularly
when we move to higher field stress magnets,” he says. “Magnets
for MRI are often measured by the magnetic field strength
that they make. The traditional high field magnet has been
1.5 Tesla, but in the past couple of years 3 Tesla magnets
have been available. We’ve pushed resolution on 3 Tesla
magnets to the point where the resolution is almost as good
as that of digital mammogram. We’re capturing images
that are about half the resolution of a digital mammogram,
which is rather astounding for MRI.”
High Spatial and Temporal Resolution
Penn physicians have also worked aggressively to define an
innovative pulse sequence technique that enables them to
get high spatial resolution and high temporal resolution
at the same time. “We don’t yet have good data
on the clinical advantage, but what we do know is that
we can take very high spatial resolution images in approximately
15 seconds that have traditionally taken several minutes,” says
Dr. Schnall. “This additional speed better enables
us to look at what the contrast is doing as a function
of time, which hopefully will allow us to be more specific
in diagnosing cancer.”
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