Mammograms have been a big help in early detection of breast cancer. However, if you are in the high risk range, if you've already had breast cancer in one breast, or if you have a family history of breast cancer, then it's advised that you have annual magnetic resonance imaging (MRI) as well.

An article on CBC News.Ca suggests other cases where MRIs should be used to detect breast cancer:

• A mutation in the BRCA1 or BRCA2 genes.
  


• Been treated for Hodgkin's disease.
  


• Had a strong family history of the disease, such as women with two or more close relatives who have breast or ovarian cancer, or who have a close relative who developed breast cancer before age 50.

Why should MRIs be utilized in these cases? CBC News states:

MRIs are better at showing increased or abnormal blood flow in the breast, a sign of early cancers not visible on a mammogram. They also are better than mammograms at detecting cancer in women with dense, non-fatty breasts.

MRIs can also detect how well a tumor is going to respond to treatment. The Science Blog has this to say:

Scientists at the Duke Comprehensive Cancer Center have shown they can use magnetic resonance imaging (MRI) to visualize and ''score'' a breast cancer tumor's ability to respond to cancer-killing drugs.

Using this novel technique, the researchers predicted with 90 percent accuracy which tumors would respond when treated with ''neoadjuvant'' chemotherapy and which tumors would not. Neoadjuvant means the drugs are given before surgery, rather than after, to shrink the tumor and improve the patient's outcome.