Assessment of breast tissue changes on hormonal replacement therapy using MRI: A pilot study

Purpose: The purpose of this study was to investigate, using MRI, the poten tial morphologic effects of hormonal replacement therapy (HRT) on breast ti ssue in postmenopausal 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 progestag en (1 mg/day). T1-weighted (TR 11 ms, TE 4.65 ms, flip angle 35 degrees, tw o excitations) 3D MR scans were acquired on a 1.5 T whole-body scanner befo re therapy and after each regimen. With use of a segmentation algorithm and histogram evaluation, parenchymal tissue/fat ratios were calculated over t argeted volumes and changes were assessed. Results: An increase in these ratios was observed in two subjects after rec eiving the combined therapy, indicating a change in parenchymal pattern, wh ereas no obvious changes were detected in any of the subjects during the es trogen-based therapy. Conclusion: MRI is able to detect and quantitate changes in breast parenchy ma during HRT.