Faculty Bibliography

OBJECTIVE: Breast density is increasingly recognized as an independent risk factor for the development of breast cancer, because it has been shown to be associated with a four- to sixfold increase in a woman's risk of malignant breast disease. Increased breast density as identified on mammography is also known to decrease the diagnostic sensitivity of the examination, which is of great concern to women at increased risk for breast cancer. Dense tissue has generally been associated with younger age and premenopausal status, with the assumption that breast density gradually decreases after menopause. However, the actual proportion of older women with dense breasts is unknown. The purpose of this study was to examine the relationship between age and breast density, particularly focusing on postmenopausal women. MATERIALS AND METHODS: All screening mammograms completed at the New York University Langone Medical Center in 2008 were retrospectively reviewed. Analysis of variance and descriptive analyses were used to evaluate the relationship between patient age and breast density. RESULTS: A total of 7007 screening mammograms were performed. The median age of our cohort was 57 years. Within each subgroup categorized by decade of age, there was a normal distribution among the categories of breast density. There was a significant inverse relationship between age and breast density (p < 0.001). Seventy-four percent of patients between 40 and 49 years old had dense breasts. This percentage decreased to 57% of women in their 50s. However, 44% of women in their 60s and 36% of women in their 70s had dense breasts as characterized on their screening mammograms. CONCLUSION: In general, we found an inverse relationship between patient age and mammographic breast density. However, there were outliers at the extremes of age. A meaningful proportion of young women had predominantly fatty breasts and a subset of older women had extremely dense breasts. Increased density renders mammography a less sensitive tool for early detection. Breast density should be considered when evaluating the potential benefit of extended imaging for breast cancer screening, especially for women at increased risk for the disease.

OBJECTIVE: The purpose of this study was to evaluate the usefulness of MRI of the breast in cases in which mammographic or sonographic findings are inconclusive. MATERIALS AND METHODS: We retrospectively reviewed images from 115 MRI examinations of the breast performed from 1999 to 2005 for the indication of problem-solving for inconclusive findings on a mammogram. Forty-eight of the 115 women (41.8%) were at high risk. We discerned whether sonography or MRI was used as an adjunctive tool and correlated the findings with those in the pathology database. RESULTS: The equivocal findings most frequently leading to MRI were asymmetry and architectural distortion. No suspicious MRI correlate was found in 100 of 115 cases (87%). These cases were found stable at follow-up mammography or MRI after a mean of 34 months. Fifteen enhancing masses (13%) that corresponded to the mammographic abnormality were seen on MR images. All masses identified at MRI were accurately localized for biopsy, and six malignant lesions were identified. Four of six malignant tumors were seen in one mammographic view only; two were seen on second-look ultrasound images. MRI had a sensitivity of 100% and compared with mammography had significantly higher specificity (91.7% vs 80.7%, p = 0.029), positive predictive value (40% vs 8.7%, p = 0.032), and overall accuracy (92.2% vs 78.3%, p = 0.0052). Eighteen incidental lesions (15.7%) were detected at MRI, and all were subsequently found benign. CONCLUSION: We found breast MRI to be a useful adjunctive tool when findings at conventional imaging were equivocal. Strict patient selection criteria should be used because of the high frequency of incidental lesions seen on MR images