Purpose: To evaluate the range of normal contrast enhancement behaviour in dynamic MR mammography of healthy breast parenchyma, and to reduce false-positive results caused by incidental contrast enhancing lesions.
Materials and methods: We performed a prospective two-armed study on 20 healthy premenopausal volunteers who were examined four times within one month (Group 1) or during four consecutive months (Group 2). Incidence, prevalence, morphology, and contrast enhancement pattern of lesions were evaluated.
Results: 82% (9/11 of Group 1) and 78% (7/9 of Group 2) showed at least one of a total of 60 contrast enhancing lesions. In 54% or 33% (Group 1 or 2), lesions with enhancement velocity beyond the malignancy threshold were found. 72% or 75% of lesions resolved completely during follow-ups. 69% of lesions were focal with irregular border. Time/signal intensity diagrams were almost always not suspicious; no wash-out phenomenon was seen.
Conclusion: In MR mammography of premenopausal breast parenchyma, focal contrast enhancing lesions-even with enhancement beyond the malignancy threshold-may occur without any underlying pathology.