| |
 |
Download PDF Version of this Article
Bookmark this Site
|
|
Archived Issues of Radiology Rounds
MGH Department of Radiology Website
|
New information within this article has become available (see yellow highlighted area below)
|
New Guidelines for Breast MRI
|
| |
|
 |
In March 2007, the American Cancer Society (ACS) published new guidelines for breast screening
with MRI
|
|
Screening breast MRI is now recommended annually, as an adjunct to mammography, for high risk women including: |
| |
- Women who carry a BRCA mutation,
- Untested women with a first degree relative who has a BRCA mutation,
- Women with >20-25% estimated lifetime risk of developing breast cancer
|
|
Diagnostic
bilateral breast MRI is indicated for women with newly diagnosed breast
cancer, particularly women with a diagnosis of lobular cancer or those
with mammographically dense breast tissue, to evaluate for tumor extent
and for the presence of additional tumors
|
|
Diagnostic breast MRI may also be recommended if other breast imaging tests are inconclusive
|
|
Evidence
from recently published clinical trials on the use of breast MRI has
demonstrated its value in detecting cancers that are not apparent by
clinical examination or mammography. Conversely, it should be noted
that mammography can detect some cancers not detected by MRI.
Therefore, the American Cancer Society has published new updated
guidelines for screening high risk women which now includes an annual
MRI in addition to annual mammography. However, MRI is not recommended
as a screening tool for the general population due to the large number
of false positive findings and negative biopsies that result from the
examination, particularly in women of average risk of developing breast
cancer.
New evidence also demonstrates that diagnostic
MRI of the contralateral breast in women with newly diagnosed breast
cancer detects additional cancers not detected by other means. MRI of
the ipsilateral breast is also useful for the evaluation of tumor
extent that could affect patient management. These MRI applications are
particlularly useful in women with lobular cancer and/or
mammographically dense breast tissue. Other established uses of breast
MRI include cases in which other imaging is inconclusive and for
monitoring neo-adjuvant chemotherapy.
Screening Breast MRI for High Risk Patients
What
defines a high risk patient? Several models have been developed to
assess the risk of a woman developing cancer in her lifetime, based on
family history of breast and/or ovarian cancer, the presence of certain
gene mutations, and personal history. Several newer models of risk
assessment, such as BRCAPRO (a statistical software that calculates the
probability of breast cancer risk), incorporate detailed family
history to assess risk. Although estimates of risk are somewhat
imprecise, it is well established that some genes including BRCA1 and
BRCA2 confer significantly elevated risk and that carriers of these
genes account for about 50% of families with an inherited pattern of
breast cancer. These women often develop cancer at an earlier age than
most and have aggressive forms of cancer. The prevalence of the BRCA1
and BRCA2 mutations is between 1/500 and 1/1000 in the general
population but approaches 1/50 in women of Jewish ethnicity. Other
genetic components can also contribute to the development of breast
cancer but, in most cases, the development of breast cancer is a
sporadic event. Therefore, having a single relative with breast cancer
usually does not significantly alter an individual’s risk. The
exception is a woman with a first-degree relative who has a history of
pre-menopausal breast cancer; these women are at sufficiently increased
risk that adjunctive screening with MRI should be considered.
In addition to these familial factors, there is a consensus that
therapeutic radiation to the chest between the ages of 10 and 30, such
as occurs in the treatment of Hodgkin’s disease, also significantly
increases the risk of developing breast cancer. Table 1 shows the
clinical criteria for high risk that warrant annual MRI screening for
breast cancer. |
|
| Table 1. Recommendation Criteria for Breast MRI Screening as an Adjunct to Mammography |
Documented BRCA mutation
|
Untested women with first degree relative with BRCA mutation
|
Life-time risk of developing cancer >20-25% calculated from family and personal history
|
Radiation to chest between age 10 and 30 yrs
|
| First-degree relative with pre-menopausal breast cancer |
Diagnostic Breast MRI for Women with Recently Diagnosed Cancer
In
addition to screening, breast MRI is used to help with diganosis and
management. In a recent study in which Lehman and colleagues evaluated
969 women with newly diagnosed unilateral breast cancer, 3% were found
to have cancer in the contralateral breast that was detectable by MRI
but not by mammography or clinical examination. The estimated
sensitivity and specificity of MRI in this setting were 91% and 88%,
respectively. The negative predictive value was 99% and the positive
predictive value was 21%. Although the specifity was significantly
higher in postmenopausal than pre- or perimenopausal women, the other
values did not vary significantly with menopausal status, breast tissue
density, or histological features of the index cancers. In this series,
all of the occult cancers detected by MRI were node-negative. Because
simultaneous cancer in the contralateral breast is associated with a
high risk of metastasis (16%) and fatality (7%), patients whose cancers
are detected early may benefit from prompt treatment.
MRI also detects the presence of a second ipsilateral cancer not
apparent by mammography or clinical examination in about 10% of women
with recently diagnosed breast cancer. This additional information
regarding the extent of a patient’s cancer can alter surgical
management; if the two malignancies exist within different quadrants of
the breast, mastectomy (rather than lumpectomy) may be recommended.
While it is recognized that some of these previously undiagnosed
cancers may not be lethal, there is currently no way to judge an
individual tumor’s potential for lethality and thus all breast cancers
are treated as potentially lethal.
MRI is useful in management because it shows more extensive disease
than was initially suspected in about 20% of women. Therefore, without
MRI, these patients are at risk of incomplete surgical removal of
tumors and may have to return for additional surgery if pathologic
examination determines that the margins are not clear of evidence of
malignancy.
MRI has also been shown to be useful in detection of a primary breast
malignancy in women presenting with metastatic disease in the axillary
nodes in the setting of a negative mammogram. The identification of the
primary breast tumor by MRI may allow breast conservation in these
women who would otherwise have had to undergo mastectomy in the
treatment of their disease.
|
 |
Figure 1. Lobular carcinoma of the right breast.
Figure 2. Small invasive ductal carcinoma found on MRI screening (mammogram was negative)in a high-risk patient (cancer is circled).
|
|
Diagnostic Breast MRI to Monitor Neo-adjuvant Chemotherapy
In patients with more advanced cancers, neo-adjuvant chemotherapy is
often recommended to shrink the tumor before surgery. In these
patients, MRI may be used to assess the response of the tumor to
chemotherapy treatment. If MRI indicates that the chosen therapy has
not resulted in tumor shrinkage after a course of treatment, then an
alternative therapy may be selected.
Other Conditions in Which Breast MRI May be Recommended
Women who have had previous surgery for breast cancer, have silicone
implants, or have radiographically dense breasts may have inconclusive
results from clinical examination, mammography, and ultrasound. When
these methods of evaluation are inconclusive, the radiologist may
recommend an MRI if it is likely to provide more diagnostic
information. Breast MRI can often distinguish between scar tissue and
recurrent cancer and its image quality is not significantly impaired by
dense tissue or implants. If a clinical suspicion of silicone implant
rupture exists, breast MRI is the most accurate test for evaluation.
MRI Quality Standards
Dedicated breast MRI coils are necessary to obtain high quality MR
images of the breasts. It is critical that breast MRI be performed in a
center with access to adjunctive breast imaging tools and where there
are radiologists with expertise in all aspects of breast imaging,
including MRI-guided biopsy, to ensure that a patient can receive
comprehensive evaluation and care.
|
|
Scheduling
| Breast MRI can be scheduled through the Radiology Order Entry System (http://mghroe
) for Mass General Imaging Chelsea and the Main Campus.
|
Further Information
For further questions, please contact, Elizabeth Rafferty, M.D., Director
of Breast Imaging in the Avon Foundation Comprehensive Breast
Evaluation Center, at 617-726-3093.
We would also like to thank Michelle C. Specht, M.D., Surgical Oncology, for her assistance and advice for this issue.
This article provided useful information about the appropriate use of imaging studies:
Note: clicking one of these options will close this window.
|
References
|
|
|
Berg, WA, Gutierrez, L, NessAiver, MS, Carter, WB, Bhargavan, M, Lewis, RS and Ioffe, OB. (2004) Diagnostic accuracy of mammography, clinical examination, US, and MR imaging in preoperative assessment of breast cancer. Radiology 233: 830-49
Friedman, PD, Swaminathan, SV, Herman, K and Kalisher, L. (2006) Breast MRI: the importance of bilateral imaging. AJR Am J Roentgenol 187: 345-9
Kuhl, CK, Schrading, S, Leutner, CC, Morakkabati-Spitz, N, Wardelmann, E, Fimmers, R, Kuhn, W and Schild, HH. (2005) Mammography, breast ultrasound, and magnetic resonance imaging for surveillance of women at high familial risk for breast cancer. J Clin Oncol 23: 8469-76
Lehman, CD, Gatsonis, C, Kuhl, CK, Hendrick, RE, Pisano, ED, Hanna, L,
Peacock, S, Smazal, SF, Maki, DD, Julian, TB, DePeri, ER, Bluemke, DA
and Schnall, MD. (2007) MRI evaluation of the contralateral breast in women with recently diagnosed breast cancer. N Engl J Med 356: 1295-303
Saslow, D, Boetes, C, Burke, W, Harms, S, Leach, MO, Lehman, CD,
Morris, E, Pisano, E, Schnall, M, Sener, S, Smith, RA, Warner, E,
Yaffe, M, Andrews, KS and Russell, CA. (2007) American cancer society guidelines for breast screening with MRI as an adjunct to mammography. CA Cancer J Clin 57: 75-89
Kriege, M, Brekelmans, CT, Boetes, C, Besnard, PE, et al. (2004) Efficacy of MRI and mammography for breast-cancer screening in women with a familial or genetic predisposition. N Engl J Med 351: 427-37
Liberman, L, Morris, EA, Dershaw, DD, Abramson, AF and Tan, LK. (2003) MR imaging of the ipsilateral breast in women with percutaneously proven breast cancer. AJR Am J Roentgenol 180: 901-10
Warner, E, Plewes, DB, Hill, KA, Causer, PA, Zubovits, JT, Jong, RA,
Cutrara, MR, DeBoer, G, Yaffe, MJ, Messner, SJ, Meschino, WS, Piron, CA
and Narod, SA. (2004) Surveillance
of BRCA1 and BRCA2 mutation carriers with magnetic resonance imaging,
ultrasound, mammography, and clinical breast examination. Jama 292: 1317-25
BRCAPRO Risk Assessment Software can be found at: http://astor.som.jhmi.edu/BayesMendel/brcapro.html
|
|
|
|
|
|
|
|
