Factors Influencing Background Parenchymal Enhancement on Breast MRI Classified by Mammographic Density

Background:Mammographic dense breast or high background parenchymal enhancement (BPE) in magnetic resonance imaging (MRI)hinders diagnostic accuracy for breast tumor detection. We retrospectively investigated relationship between BPE on MRI and mammographic densities along with the influential factors. Methods:Our study included 144 Japanese women who underwent both mammography and breast MRI using a 3T unit. The subjects were classified into either mammographically dense group or fatty group,then further categorized into 4 subgroups by the degree of BPE (minimal,moderate,mild,marked)on enhanced MRI. As influential factors,their ages,menopausal status,and experience of lactation were statistically investigated. Results:73.8% of mammographically dense group showed minimal or mild BPE on the breast MRI. Women with minimal BPE in the mammographically dense group were significantly older than those with mild and marked BPE. In the mammographically fatty group,women with minimal BPE were significantly older than those with moderate BPE. Also,significant differences of BPE were shown between menopausal and premenopausal women in both mammographic groups,but experience of lactation did not influence BPE. Conclusion:BPE on MRI is considered to be affected by age and menopausal status, not by breast-feeding experience,regardless of the mammographic density.