Screening Women at High Risk of Breast Cancer by Magnetic Resonance Imaging (MRI)
July 13, 2007 | Evidence Reports
Magnetic resonance images are created by recording the signals that are generated after radio-frequency excitation of nuclear particles in tissue exposed to a strong magnetic field. A contrast agent, injected into the bloodstream, accumulates in the vascular system and can aid in locating tumors by highlighting areas containing a dense blood-vessel network.
In the general population, the incidence of breast cancer is about 0.2% per annum at age 50 and 0.05% per annum at age 35, with a cumulative lifetime risk of breast cancer of approximately 13%. Some women inherit a predisposition to developing breast cancer (high-risk women). Among these women, the incidence of breast cancer is 3% per annum at age 50 and 1% at age 35, with a cumulative lifetime risk of breast cancer of approximately 80%. Thus, high-risk women are at increased risk of breast cancer throughout life, even at very young ages.
Prophylactic surgery can reduce the risk of breast cancer in high-risk women, but this intervention is not acceptable to many high-risk women. Intensive breast-cancer screening with x-ray mammography is frequently offered to young women with an inherited predisposition to breast cancer, but the efficacy of this approach is unproven. Younger women have dense breast tissue that reduces the sensitivity of x-ray mammography. In diagnostic settings, magnetic resonance imaging (MRI) has been shown to be a sensitive method of breast imaging...