Virtual clinical trial of simultaneous digital breast tomosynthesis and mechanical imaging: model calibration and the effect of tumor depth

Simultaneous Digital Breast Tomosynthesis (DBT) and mechanical imaging (MI), called DBTMI, is a novel breast imaging method aimed at improving sensitivity and specificity of breast cancer screening. DBTMI combines improved cancer detection by three-dimensional DBT imaging, with the analysis of local stress over the compressed breast by MI, which can reduce false positive findings. The MI signal is affected by various factors, e.g., breast size, composition, tumor depth, etc. Assessing the individual effect of those factors using clinical data is difficult, due to their interdependence. These open clinical questions can be addressed by virtual clinical trials. Our current work is focused on the effects of tumor depth on the DBTMI signal. We simulated the breast anatomy by a matrix of adipose and glandular tissue compartments. Spherical tumors were inserted at various depths. The MI sensor is modeled by a compound material of PMMA and Ag. We calculated the local stress on the compressed breast surface at the tumor location and simulated the MI sensor output. We also simulated the corresponding DBT images and calculated the signal-difference-to-noise ratio (SDNR) with and without pre-processing to analyze the reduction in artifacts. Our preliminary analysis of 24 simulated tumors has shown 16% reduction in the local stress, when increasing tumor depth by 15 mm (10-25 mm from the breast surface). The SDNR improvement was highest for tumors near the sensor and the effect of pre-processing decreased with increasing tumor depth.