Some women may need to get a second test to screen for breast cancer.
The American Cancer Society is now recommending a yearly MRI for women at high risk.
Dr. Johannes Heyns, a diagnostic radiologist with Radiology and Nuclear Medicine, says mammography uses x-ray radiation, while MRI uses a magnetic field to get images.
For the MRI, a woman would lie on her stomach, her breasts through an opening in the table. She's injected with contrast dye. Dr. Heyns says masses will take up the dye, drawing attention to possible cancers a mammogram may miss.
Once used only after a mammogram had spotted something suspicious, the American Cancer Society is now recommending some women get an annual MRI for cancer screening. It's for those women at highest risk. That means either they or a sibling has a certain genetic trait (a mutation of BRCA1 or BRCA2); they've had breast cancer before; or they've received radiation treatment to the chest between ages ten and 30 for a disease such as Hodgkin.
But MRI screening isn't for eveyrone. Dr. Heyns says, first, it's very expensive - about $1000, which is ten times the cost of mammography. It's also very time consuming. The MRI exam takes at least 45 minutes to complete. Dr. Heyns says that means you can do only ten to 12 MRI patients a day versus 60 to 70 mammograms.
Plus, while the MRI is sensitive, Dr. Heyns says it's not very specific, meaning more false positives. He also says it doesn't see everything a mammogram can. He says a mammogram can see calcifications which is also a sign of cancer and that may not be associated with a mass and can't be seen on MRI.
Dr. Heyns stresses MRI does not replace mammogram. He says it's an extra imaging that works together with it.
Even with the drawbacks, for women at highest risk, Dr. Heyns says adding an MRI is worth it. He says the patient will benefit from the peace of mind she gets from the MRI.