Quantitative breast density in Contrast-Enhanced Mammography

Abstract

Background: Breast density is an independent risk factor for breast cancer, and cancer detection in mammography is reduced in dense breasts. Quantitative tools are available to measure breast density from digital mammography (DM) or tomosynthesis (DBT). Contrast-enhanced mammography (CEM) is an emerging breast imaging technique, consisting of the acquisition of an image pair (low-energy, LE, and high-energy, HE) for each mammography view. LE-CEM images have been demonstrated to be visually equivalent to a standard mammogram, thereby, CEM examinations do not require additional mammography to complete the clinical information. In this study, volumetric breast density (VBD) measured in LE-CEM was compared with VBD obtained from DM/DBT images.Methods: Between Mar 2019 and Dec 2020 222 women were enrolled in a prospective clinical trial aiming to compare clinical performance of CEM with breast MRI in a population of women at intermediate and high risk for breast cancer. In this observational cohort study, 150 women enrolled in this trial having at least a DM/DBT study performed before/after CEM were selected. CEM and previous/subsequent DM/DBT images were processed by an automatic algorithm to calculate VBD for each view. VBD from LE-CEM and DM/DBT views were compared using a paired Wilcoxon test. P < 0.05 was considered indicative of a statistically significant difference. A multivariate regression model was applied to analyze the relationship between paired VBD differences and multiple independent variables certainly or potentially affecting VBD.Results: Mean age of women included in this study was 51.0±8.4 years. Median VBD was comparable for LE-CEM and previous/subsequent DM/DBT (12.73% vs. 12.39%), not evidencing any statistically significant difference (P = 0.5855). VBD differences between LE-CEM and DM were associated to significant differences of glandular volume, breast thickness, compression force and pressure, contact area, and nipple-to-posterior-edge distance i.e. variables reflecting differences in breast positioning (coefficient of determination 0.6023; multiple correlation coefficient 0.7761).Conclusions: Volumetric breast density can be obtained from low-energy contrast-enhanced spectral mammography and is not significantly different from volumetric breast density measured from standard mammograms.