About 5 percent to 10 percent of breast cancers can be traced to hereditary mutations, and women who carry these genes are considered at high risk. Standard mammograms have sometimes failed to detect breast cancers early in this population; however, researchers recently discovered that these women may benefit from MRI screening.Dr. Constance Dobbins Lehman from the University of Washington Medical Center and from the Seattle Cancer Care Alliance, both in Seattle, and her colleagues tested how well mammography, MRI and ultrasound detect breast cancer in high-risk patients. As reported in the August issue of Radiology, researchers from six facilities screened 171 high-risk women 25 years or older with all three modalities.All of the imaging methods were used on each woman within 90 days of each other. Fifteen readers participated and were assigned to one imaging method to ensure blinded readings. Six cancers were detected among the study participants. MRI detected all six of the cancers, while mammography detected only two, and ultrasound detected one. However, MRI findings also resulted in 8.2 percent of the 171 patients receiving biopsies, as compared with 2.3 percent both for mammography and for ultrasound.The researchers believe that their results indicate that the addition of MRI screenings to the standard mammogram might help detect breast cancers in high-risk women. Further studies on the potential role of ultrasound are needed.