Purpose: The purpose of this study was to investigate, using MRI, the potential morphologic effects of hormonal replacement therapy (HRT) on breast tissue in post-menopausal women.
Method: Five subjects were enrolled who were treated subsequently with both estrogen (2 mg/day) and a combination of estrogen (2 mg/day) and progestagen (1 mg/day). T1-weighted (TR 11 ms, TE 4.65 ms, flip angle 35 degrees, two excitations) 3D MR scans were acquired on a 1.5 T whole-body scanner before therapy and after each regimen. With use of a segmentation algorithm and histogram evaluation, parenchymal tissue/fat ratios were calculated over targeted volumes and changes were assessed.
Results: An increase in these ratios was observed in two subjects after receiving the combined therapy, indicating a change in parenchymal pattern, whereas no obvious changes were detected in any of the subjects during the estrogen-based therapy.
Conclusion: MRI is able to detect and quantitate changes in breast parenchyma during HRT.