Assessment of reproducibility of volumetric breast density measurement using dual energy digital breast tomosynthesis

Breast density (BD) has been shown to be an independent risk factor for breast cancer, and it can be quantified by measuring the volumetric breast density (VBD). The longitudinal change in VBD has been used as a biomarker to assess the effect of chemoprevention drug for breast cancer risk reduction. However, the reproducibility of VBD measurement is hindered by breast compression, which causes temporal changes in the distribution of breast tissues, making it difficult to assess small longitudinal changes in VBD. Dual energy digital breast tomosynthesis (DE DBT) may provide more reproducible VBD measurements over different breast compressions. In this study, we aim to evaluate the reproducibility of VBD measurement using DE DBT. Digital breast phantoms were generated using a virtual clinical trial software (VICTRE) and were compressed multiple times into different clinical-relevant compressed breast thicknesses to emulate the change in repeated imaging of the same breast. The compressed thickness difference of 10 mm exaggerates the variation seen in clinical practice. DE DBT projection images of the phantoms were generated by Monte-Carlo simulations and included quantum noise and scatter radiation. A previously developed scatter correction method and a DE material decomposition technique were applied to obtain the BD map and calculate VBD. Our results show that DE DBT can provide reproducible VBD measurements for breasts under different compressions with the average absolute discrepancy of 2.3% ± 1.1% between two repeated measurements for all phantoms. The largest discrepancy is 3.9% for the extreme case with 20 mm compressed thickness difference.