Submit your question for Dr. Mary Mason

Dr. Mary Mason wants to hear from you. She's answers your health questions every Wednesday on News 4 at Noon. This week, she's answering questions on MRI's and breast cancer.

Q: How does a mammogram and MRI spot potential breast tumors?

A: Mammograms reproduce a two-dimensional X-ray or digital picture and are the traditional way to screen for breast cancer.  Mammograms pick up breast cancer calcifications which look like white spots on film. These calcifications are common, and most women have some, but tighter clusters of calcifications in irregular shapes can  suggest breast cancer.

Magnetic resonance imaging, or MRI, uses magnetic fields make detailed images without radiation.   .  Potential tumors stand out because they have high blood flow- which can be seen on the detailed slices of the breast.

Q: Is an MRI a better test for screening for breast cancer?

A: Several large studies of women at high risk of breast cancer have shown that MRI found at least twice as many potential tumors as mammograms   And MRI is not perfect- they are many more false positives than mammograms. Doctors are twice as likely to biopsy a MRI image than something seen on mammogram.  60-80% of the time the suspicious lesion on MRI turns out to be normal tissue.  And cost is a factor- An MRI scan costs $700 to $1,000 — about 10 times the cost of a mammogram. But most insurance companies will cover for high risk women.

Q: Who should get an annual MRI scan?

A: According to the American Cancer Society Guidelines, Women who have a lifetime breast cancer risk of at least 20 percent -- should get annual breast MRI’s. . That includes women who know they carry one of the so-called breast cancer genes -- BRCA1 and BRCA2 -- as well as close or first degree relatives who have not yet been tested.  Also women with a strong family history of breast or ovarian cancer may also be considered candidates.

Other high risk groups- Women who were treated with radiation to the chest -- usually for Hodgkin's Disease -- between the ages of 10 and 30 Women who have been recently diagnosed with breast cancer should get an MRI scan of the other breast to be sure there are no other tumors

For lower risk women, there is not enough evidence to recommend a MRI in additional to their annual mammogram.

If I get an MRI, do you still need a mammogram?

Yes,   Screening is best in high risk women when both methods are combined.  One study found that mammograms alone found 40 percent of the known tumors in high-risk women compared with 77 percent detected by MRI. When the two methods were combined, the 92 percent of the tumors were diagnosed. 

About Dr. Mary Mason:

Dr. Mason is board certified in Internal Medicine and is the Assistant Clinical Professor at Washington University School of Medicine. She went to medical school at Washington University, and did her Internal Medicine Residency and
was Chief Resident for Internal Medicine at Barnes-Jewish Hospital.  Dr. Mason teaches in the internal medicine residency clinic.