Volumetric breast density estimation using dual energy digital breast tomosynthesis

Dense breast tissue has been shown to reduce the sensitivity and specificity of breast cancer detection. Estimation of breast density (BD) in digital breast tomosynthesis (DBT) may provide masking risk assessment in quasi three dimensions (3D). Dual energy (DE) mammography has been used for breast tissue decomposition, which may provide more accurate BD map for DBT projections. This study aims to investigate the feasibility of DE DBT for volumetric BD estimation and 3D masking risk assessment. A compressed digital breast phantom (with ground truth for BD) was simulated using a virtual clinical trial software (VICTRE). Low and high energy projection images of the phantom were simulated emulating the Siemens Mammomat Inspiration DBT system. DE decomposition was performed for each projection angle using a library of calibrated DE attenuation data for various combinations of breast thickness and glandularity. The resulted BD maps for all projection angles were used for simple-back-projection image reconstruction, and the dense regions for each image slice were segmented based on the reconstructed voxel values. This method was applied to clinical images from DE DBT acquisition after scatter correction. Our results show that DE decomposition provides consistent BD map for each projection angle and throughout the entire breast (including the periphery with thickness roll-off), and consistent measurements of the total breast volume, fibroglandular tissue volume and volumetric BD. The 3D segmented fibroglandular tissue map can be used to assess the masking risk for the DBT image volume.