Longitudinal fluctuations in reported background parenchymal enhancement on contrast enhanced mammography

Background parenchymal enhancement (BPE) and mammographic density (MD) are imaging biomarkers derived from contrast-enhanced mammography (CEM). However, unlike MD, the consistency of BPE across consecutive examinations in pre- and postmenopausal women has remained unexplored.

A computational search was conducted for all screening CEM exams performed at our facility between December-2012 and January-2024 to identify patients with at least five consecutive negative annual screenings. BPE grades and MD categories were extracted from the official radiology reports, and their variability parameters were statistically compared both between these factors and across age groups.

Forty-five eligible patients at premenopausal age-group were identified (mean age at first scan 38.2 ± 3.4 years, range: 27-42) and a matched postmenopausal age-group was assembled (mean age at first scan 63.7 ± 3.8 years, range: 60-74), resulting in 450 CEMs analyzed. BPE demonstrated greater variability than MD, including fluctuations of at least one category on the scale (71.1-91.1 %), two-category changes (17.8-22.2 %), and transitions between low and high binary categories (17.8-27.7 %) (P < 0.01 for all). Similar rates of two-category BPE transitions (P = 0.65) and shifts between low and high binary categories (P = 0.32) were observed in pre- and postmenopausal women; however, the latter group had a significantly smaller proportion of cases with five consistent grades (P = 0.02).

BPE on CEM demonstrates greater longitudinal variability than MD across all age groups and is not more pronounced in premenopausal compared to postmenopausal women. This highlights its dynamic nature and underscores the need for caution when considering BPE in clinical decision-making or as a biomarker, while also suggesting that strict menstrual cycle phase targeting may be less critical.