Purpose: To define the range of normal contrast medium enhancement, the variability in contrast medium enhancement patterns in healthy premenopausal breast parenchyma, and the implications for management strategies in cases with incidental contrast medium-enhancing foci on breast magnetic resonance (MR) images.
Materials and methods: Twenty healthy volunteers (aged 21-41 years) were examined on a 1.5-T system (dynamic two-dimensional gradient-echo protocol with subtraction postprocessing) during each week of a menstrual cycle (group 1) or over 4 months (group 2). The authors evaluated changes in the number of enhancing foci and the respective enhancement patterns within a cycle and between cycles.
Results: Both diffuse and nodular enhancement of breast parenchyma occurred during all phases of the menstrual cycle, especially in weeks 1 and 4. Enhancement was lowest in week 2. A total of 60 enhancing foci (73% of which resolved completely during follow-up) were found in 16 of 20 volunteers. Twenty-six foci demonstrated enhancement velocities beyond the malignancy threshold (>80% increase in the 1st minute).
Conclusion: Contrast-enhancing foci are normal in healthy premenopausal breasts, even when formal malignancy criteria of enhancement velocity are met. This has to be kept in mind to avoid false-positive results, especially in younger patients.