Cancers that are not seen on a mammogram may be found by a screening breast ultrasound or a screening breast magnetic resonance image (MRI). These tests may be needed for women who are at high risk of developing breast cancer as well as women with dense breasts. At Northwestern Medicine, we prefer to use a breast MRI over ultrasound for additional screening since it is the most sensitive examination to look for breast cancer.
During a screening breast MRI, gadolinium (contrast dye) will be injected into one of your veins. You will be positioned on your stomach for 15 minutes. If you are not able to tolerate either of these, a screening ultrasound may be better suited for you.
Even though you may need supplemental screening tests, you will still need to have a mammogram. Mammograms find cancers that may not be seen on either MRI or ultrasound. Therefore, mammograms are always done in addition to supplemental screening.
Supplemental screening is not for all women. The benefits of finding more cancers earlier must be balanced with the risk of doing more follow-up imaging and breast biopsies on benign tissue. Supplemental screening decisions should be discussed with your breast radiologist, and your primary care physician or gynecologist.