Like a colorblind coach who can see all the players but cannot
tell who is friendly, x-ray mammography is effective in finding
suspicious breast lesions but is not reliable in determining which
ones are cancerous. Because of this uncertainty, about 500,000
women have their breast lesions examined by surgical biopsy each
year, even though most biopsies show the tissue to be benign.
Research carried out at the University of Wisconsin Medical School
in Madison suggests that MRI can clear up many questions left
unanswered by conventional imaging systems, and may significantly
reduce the number of surgical breast biopsies.
A recent study led by diagnostic radiologist Dr. Frederick Kelcz
used special MRI techniques to classify 72 breast lesions in 70
women at the University of Wisconsin Hospital and Clinics. By
comparing MRI-based predictions with biopsy results, Kelcz' team
was able to correctly predict 50 of 55 benign lesions and 14 of
17 malignant lesions. Kelcz presented findings from the 3-year
study at a recent Radiological Society of North America meeting.
"In our study, MRI could have reduced the unnecessary biopsy
rate by 90%," Dr. Kelcz said. "Even though MRI is expensive,
surgical biopsy is several times more costly. Ultimately, MRI
may prove cost-effective for determining which women really need
Women in the study were examined with dynamic, enhanced MRI when
a mammogram or breast examination suggested a problem requiring
biopsy. The women were injected with a dye during a rapid series
of MRI images. In general, the faster the magnetic dye was absorbed
by a breast mass, the more likely it was that the mass was malignant.
In the current study, about one-third of breast abnormalities
did not take up the dye, and all of these were benign, Dr. Kelcz
The University of Wisconsin study is part of a worldwide effort
to improve the technology used in diagnosing and managing cancer
and other breast problems. Mammography is the most cost-effective
method for the large-scale detection of breast abnormalities.
But signs of malignancy can be subtle on x-ray film, where all
breast tissues overlap. This makes it difficult for doctors to
find or classify some abnormalities, said Dr. Kelcz, who is Associate
Professor of Radiology at the University of Wisconsin Medical
Magnetic resonance imaging, which produces cross-sectional pictures
of soft tissue, has rapidly become the primary imaging method
for diagnosing brain and spinal cord abnormalities and checking
breast implants for leakage. "MRI won't replace mammography
or biopsy, but it may become an important problem-solving tool
for breast cancer," Dr. Kelcz said. The study suggested several
situations in which MRI might supplement a mammographic examination:
When a suspected cancerous lesion can be seen only on one mammographic
view, as can happen with the dense glandular breast tissue common
in younger women and in older women on hormonal therapy
When deciding between lumpectomy or mastectomy (MRI may reveal
previously undetected lesions, suggesting an advantage to mastectomy.)
After lumpectomy to ensure that all malignant tissue has been
removed and to distinguish scar tissue from recurrent tumor
When a mammogram shows multiple lesions in a woman with a strong
family history of breast cancer.
Dr. Kelcz cautioned that MRI should not be used as a general substitute
for mammography or biopsy. "MRI alone would have misdiagnosed
three cancers detected by mammography, so we advise patients with
a negative MRI to get at least two follow-up examinations at six
month intervals to make sure that the abnormality is not growing,"'
he said. The Madison researchers are working to increase MRI's
In addition, the study showed that it isn't cost-effective to
use MRI when conventional imaging systems suggest a lesion with
a high likelihood of being either benign or malignant, Dr. Kelcz
said. Magnetic resonance imaging also can be inaccurate in trying
to diagnose malignancy when mammography shows a small cluster
of very tiny calcifications.
Dr. Kelcz' interest in breast MRI stemmed from his experience
in interpreting mammograms: "For other parts of the body,
we have several methods to help us decide whether or not an abnormality
is cancer," he said. "In the breast, however, there
was little we could suggest aside from biopsy or follow-up mammography."
In the future, MRI could provide essential information to women
who have a strong family history of breast cancer or who test
positive for the "breast cancer gene" but have negative
mammograms, Dr. Kelcz speculated.