Impact of Hormone-Secreting Intrauterine Device on Background Parenchymal Enhancement in Contrast-Enhanced Mammography

Background: Recent evidence suggests that levonorgestrel-releasing intrauterine devices (LNG-IUDs) exert more significant systemic hormonal activity than previously assumed. Background parenchymal enhancement (BPE), which refers to the normal enhancement of fibroglandular breast tissue after contrast administration, is known to be sensitive to hormonal fluctuations. Although increased BPE on breast magnetic resonance imaging (MRI) has been documented in LNG-IUD users, this association has not been previously evaluated using contrast-enhanced mammography (CEM).
Methods: This retrospective study included 300 premenopausal women (aged 40–52) who underwent CEM between 2015 and 2024. The cohort was divided into Group A (100 LNG-IUD users) and Group B (200 non-users). Three radiologists independently assessed BPE using American College of Radiology (ACR) Breast Imaging Reporting and Data System (BI-RADS) categories (0: minimal, 1: mild, 2: moderate, 3: marked). Secondary outcomes included ultrasound (US) and MRI referral rates and final BI-RADS assessment categories.
Results: BPE was significantly higher in the LNG-IUD group compared to the control group, with reader-averaged BPE score median values of 1.7 and 1.0 , respectively (p < 0.001). Moderate or marked BPE (categories 2–3) was significantly more prevalent in LNG-IUD users (61.0%) than in non-users (29.0%), resulting in an odds ratio of 3.8 (95% CI: 2.3–6.3). Accordingly, LNG-IUD users faced significantly higher rates of US referrals (93% vs. 62%, p < 0.001) and MRI referrals (22% vs. 8%, p = 0.001). Final BI-RADS categories were also significantly higher in the LNG-IUD group (p < 0.001).
Conclusions: LNG-IUD use is associated with significantly increased BPE on CEM, supporting the hypothesis of systemic hormonal effects on breast tissue. This increased enhancement can complicate image interpretation, leading to higher BI-RADS assessments and more frequent downstream imaging referrals, which may impact clinical resource utilization.