Objective: To evaluate the effect of menopausal status on the background parenchymal enhancement (BPE) and amount of fibroglandular tissue (FGT) on breast MRI.
Methods: Retrospective review identified 1,130 women who underwent screening breast MRI between July and November 2010. In 28 of these women, breast MRI was performed both at one time point while pre- and one time point while post-menopausal (median interval 49 months). Two independent readers blinded to menopausal status used categorical scales to rate BPE (minimal/mild/moderate/marked) and FGT (fatty/scattered/heterogeneously dense/dense). Consensus was reached when there was disagreement. The sign test was used to assess changes in rating categories, and the Spearman rank and Fisher's exact tests were used to measure correlations and associations between variables.
Results: Significant proportions of women demonstrated decreases in BPE and FGT on post-menopausal breast MRI (P = 0.0001 and P = 0.0009). BPE category was unchanged in 39 % (11/28) and decreased in 61 % (17/28) of women. FGT category was unchanged in 61 % (17/28) and decreased in 39 % (11/28) of women. Age, reason for menopause, or interval between MRIs had no significant impact on changes in BPE and FGT.
Conclusion: On MRI, BPE, and FGT decrease after menopause in significant proportions of women; BPE decreases more than FGT.
Key points: On MRI, background parenchymal enhancement and fibroglandular tissue both decrease after menopause. The reduced postmenopausal enhancement is more marked in parenchyma than fibroglandular tissue. Background enhancement and fibroglandular tissue seen on MRI are under hormonal influence.