Measuring Breast Motion At Multiple Dbt Compression Levels Using Ultrasound Speckle-Tracking Techniques

The goal of this study is to investigate whether reduced breast compression in digital breast tomosynthesis (DBT) exams causes larger internal breast motion that would adversely affect DBT image quality. We designed an experiment to collect real-time breast motion data from patients using ultrasound under three levels of DBT compression (full, medium and half). The ultrasound RF data had a pixel size of 21.5 mu m and 150 mu m in the axial and lateral directions of the probe, allowing the tracking of very fine movement of internal structure. We have successfully collected data from six human subjects and continue to recruit patients. The data were analyzed using speckle-tracking techniques to extract internal tissue movement trajectories pixel by pixel at multiple locations. Initial data analysis showed that internal breast tissue movement is highly correlated with breathing. Based on the first four patient datasets we have processed, the internal motion magnitudes on average were smaller than 1 mm under the full and reduced compression levels. The statistical distributions of the motion magnitudes among the three compression levels were similar, indicating that the internal breast motion may not necessarily increase even when compression is reduced by half. However, more data will be collected and analyzed to strengthen this study for more solid conclusions.