Contrast-Enhanced Mammograms: What Are They and How Do They Work?

Mammograms use X-rays to screen for breast cancer and help diagnose it. A contrast-enhanced mammogram (CEM) — sometimes called a mammogram with contrast — is a special type of mammography that uses an iodine-based dye to show any potential breast cancer more clearly.

Doctors most often use contrast-enhanced mammograms as a follow-up test after something unusual is seen on a standard mammogram, but they may also be used for screening in some people with dense breast tissue.

A contrast-enhanced mammogram is similar to a typical mammogram, but before the images are taken, you’re given an IV of iodine-based dye, called contrast.  

After the iodine contrast is injected, the mammogram takes both standard and contrast-enhanced images. The contrast helps highlight growths in the breasts. In particular, the dye makes it easier to see abnormal blood vessels that grow to feed cancer.

The Food and Drug Administration has approved contrast-enhanced mammograms as a diagnostic tool. This means it can be used after something unusual is seen on a standard mammogram to help rule out or diagnose breast cancer. It can also be used instead of a standard mammogram for people with symptoms like lumps, skin dimpling, or nipple discharge. 

In addition, contrast-enhanced mammograms can show how far breast cancer has spread in people with a new diagnosis, and how the cancer is responding to chemotherapy given before surgery (neoadjuvant chemotherapy). Researchers are also studying whether contrast-enhanced mammograms may be useful for screening in people with dense breast tissue.

People with dense breasts have a higher risk that breast cancer may be missed on a regular mammogram. That’s because dense breast tissue shows up as solid white on a mammogram, and so does breast cancer.

Experts don’t agree on whether people with dense breasts should have additional breast cancer screening beyond a standard mammogram, but some states require insurance to pay for additional testing if your doctor recommends it for you. This additional testing may detect cancers not seen on a standard mammogram, but there is not much information about the long-term benefit of additional testing.

Additional screening for people with dense breasts is usually an MRI, ultrasound, or contrast-enhanced mammogram. In a large U.K. trial published in The Lancet, contrast-enhanced mammography and MRI detected about three times as many invasive breast cancers as ultrasound in women with dense breast tissue. The cancers found tended to be smaller, which may reflect early detection.

If you’re deciding between contrast-enhanced mammograms and MRI, contrast-enhanced mammograms may be a better option for some people because they’re less expensive than MRI. MRI has some other drawbacks: It isn’t available everywhere and may require longer wait times. It may not be the best option for people who have claustrophobia, obesity, or neck issues. And it may not be the safest option for people with breathing problems or some metal implants like pacemakers. 

The cost of contrast-enhanced mammography can vary depending on your insurance coverage and where you have the test.

Before your appointment, check with your facility on how long you should be fasting before the test, because the contrast may cause nausea and vomiting. Don’t wear deodorant, lotion, cream, oils, or perfumes.

Before the mammogram, you’ll have an IV placed, and the contrast will be injected. This may feel warm, and you may get a metallic taste in your mouth.

After several minutes, you’ll have the mammogram. It will feel the same as a regular mammogram, but it uses about 30% to 50% more radiation. This is still within a safe level of exposure to radiation. 

Plan for the appointment to last about an hour in total. In the 24 hours following your appointment, drink plenty of water to help flush the contrast from your system.

Contrast-enhanced mammography isn’t suitable for everyone. Some people may be allergic to the contrast without knowing it. If this happens, they can have mild side effects like hives. In rare cases, they may have a serious allergic reaction, called anaphylaxis.

People with kidney problems may not be eligible for contrast-enhanced mammograms. If you have mild kidney problems, you may be able to get one along with IV hydration before or after the exam to help protect your kidneys.

Contrast-enhanced mammograms also aren't recommended during pregnancy. They’re safe to get if you’re breastfeeding — only a tiny amount of the contrast (which is deemed safe for babies) gets into the breast milk. But it is enough to affect the taste of the breast milk for 12 to 24 hours following your appointment. For that reason, some people choose to “pump and dump” and resume normal breastfeeding after 12–24 hours.

If a normal mammogram reveals that you have dense breast tissue, ask your doctor if you should get contrast-enhanced mammograms going forward.  Contrast-enhanced mammograms can help catch what standard imaging might miss, particularly in dense breast tissue. But they come with caveats, including added radiation and contrast dye, and they aren’t the right choice for everyone, making it important to weigh the benefits against the risks.