CONTRAST-ENHANCED MAMMOGRAPHY: THE EMERGENT CONTRAST-ENHANCED BREAST IMAGING MODALITY

Purpose: To evaluate if background parenchymal enhancement (BPE) on contrast-enhanced mammography (CEM), graded according to 2022 CEM-dedicated Breast Imaging Reporting and Data System (BI-RADS) lexicon, is associated with breast density, menstrual status, and age. Methods: This bi-centric retrospective analysis included CEM examinations performed for second-level assessment of suspicious mammographic findings. Three readers independently and blindly evaluated BPE on recombined CEM images and breast density on low-energy CEM images. Inter-reader reliability was estimated using Fleiss κ. Multivariable binary logistic regression was performed, dichotomising breast density and BPE as low (a/b BI-RADS categories, minimal/mild BPE) and high (c/d BI-RADS categories, moderate/marked BPE). Results: A total of 200 women (median age 56.8 years, interquartile range 50.5−65.6, 140/200 in menopause) were included. Breast density was classified as a in 27/200 patients (13.5%), as b in 110/200 (55.0%), as c in 52/200 (26.0%), and as d in 11/200 (5.5%), with moderate inter-reader reliability (κ=0.536; 95% confidence interval [CI] 0.482–0.590). BPE was minimal in 95/200 patients (47.5%), mild in 64/200 (32.0%), moderate in 25/200 (12.5%), marked in 16/200 (8.0%), with substantial inter-reader reliability (κ=0.634; 95% CI 0.581–0.686). At multivariable logistic regression, pre-menopausal status and breast density were significant positive predictors of high BPE, with adjusted odds ratios of 6.120 (95% CI 1.847–20.281, p=0.003) and 2.416 (95% CI 1.095–5.332, p=0.029) respectively. Conclusion: BPE on CEM is associated with well-established breast cancer risk factors, being higher in women with higher breast density and pre-menopausal status.