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Limitations to an MRI Exam of the Breast

While MRI has significant promise as a supplemental tool to mammography in the diagnosis of breast cancer, there are limitations associated with MRI. First, MRI cannot always distinguish between cancerous and non-cancerous abnormalities, which can lead to unnecessary breast biopsies. Another drawback of breast MRI is that has historically been unable to effectively image calcifications, tiny calcium deposits that can indicate breast cancer. However, MRI technology is improving in this area. Still, mammography can reliably image calcifications, which are often associated with early-stage breast cancers such as ductal carcinoma in situ (DCIS).

Another drawback of breast MRI is that has historically been unable to image calcifications, tiny calcium deposits that can indicate breast cancer. Mammography, on the other hand, can reliably image calcifications, which are often associated with early-stage breast cancers such as ductal carcinoma in situ (DCIS).

MRI image showing DCIS. Image courtesy of Siemens Medical.

Another potential drawback of MRI is that it has been shown to produce a moderate amount of false-positive results. In other words, the results of an MRI sometimes show that a suspicious abnormality is present in the breast when, in fact, cancer is not present. To some degree, all medical tests tend to lose some of their value when used in populations where the disease is not common.

Furthermore, MRI is an expensive exam; an average MRI of the breast costs approximately $1000 versus $100 per screening mammogram. MRI can also take longer than mammography: more than 30 minutes in addition to the administration of the contrast versus 10 to 15 minutes for a screening mammogram. Patients need to lie still in a prone (face down) position during the exam to eliminate motion in the images. Though an MRI exam is not painful, patients must tolerate any claustrophobia (fear of small spaces) they may have. A contrast agent is also given prior to the exam to improve image quality. See the above section on How Breast MRI is Performed for more information on the contrast agent.

Finally, MRI is not nearly as widely available as mammography. However, access is increasing, and breast MRI is the second fastest growing MR procedure in the United States. In 2004, 24% of all facilities offering MR services offered breast MRI. According the Advisory Board, by 2010, an estimated 860,000 breast MR procedures will be performed.

Summary

To summarize, when used in conjunction with mammography, breast MRI can be a very useful breast cancer diagnostic tool. In particular, MRI as been shown to effectively image the augmented breast. MRI can be used effectively to gain information about breast abnormalities detected with mammography, physical exam, or other breast imaging modalities. Because of the increased sensitivity of MRI, the American Cancer Society recently recommended that young women at very high risk of the disease receive annual MRI exams in addition to annual mammograms. MRI may also useful for women diagnosed with breast cancer to detect cancer in the opposite breast, evaluate treatment options, and follow-up after treatment has been completed.

While breast MRI is an effective in some cases, it has limitations that prevent physicians from using it as a widespread screening tool for breast cancer. Its increased cost over mammography and frequent inability to distinguish between cancerous and non-cancerous abnormalities are drawbacks. However, the American Cancer Society's recent endorsement of MRI as a screening tool in young women at very high risk of breast cancer shows that the technology is beginning to play a more significant role in breast cancer detection.

The following chart summarizes the benefits and limitations of breast MRI:

 Click Here to View Breast MRI Case Studies.

 Click here for General Information on MRI.

Updated: May 4, 2008

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