How do an MRI and a mammogram differ as breast cancer screening tools?

Breast MRI is more sensitive than a mammogram. Women who have indeterminate findings on either a mammogram or sonography may benefit from breast magnetic resonance imaging (MRI). MRI may specifically characterize a questionable lesion to determine whether a biopsy is needed. Women at high risk for developing breast carcinoma (e.g., family history or carriers of predisposing gene) may benefit from MRI screening to determine if no occult breast tumor is present.

Normal mammograms use x-rays to look at the breast tissue to search for abnormalities. Magnetic resonance imaging (MRI), on the other hand, uses no x-rays. MRI uses a contrast agent that makes it easier to see the breast tissue. With MRI, the contrast between soft tissues in the breast is 10 to 100 times greater than that obtained with x-rays.