Angular spatial compounding of diffraction corrected images improves ultrasound attenuation measurements

Breast cancer is a leading cause of death for women. Quantitative ultrasound (QUS) and ultrasound computed tomography (USCT) are quantitative imaging techniques that have been investigated for management of breast cancer. QUS and USCT can generate ultrasound attenuation images. In QUS, the spectral log difference (SLD) is a technique that can provide estimates of the attenuation coefficient slope. Full angular spatial compounding (FASC) can be used with SLD to generate attenuation maps with better spatial resolution and lower estimate variance. In USCT, high quality speed of sound (SOS) images can be generated using full wave inversion (FWI) method, but attenuation images created using FWI are often of inferior quality. With the QTI Breast Acoustic CT^TM Scanner (QT Imaging, Inc., Novato, CA), raw in-phase and quadrature data were used to implement SLD combined with FASC. The capabilities of SLD were compared with FWI through simulations, phantom experiments, and in vivo breast experiments. Results show the SLD resulted in improved accuracy in estimating lesion sizes compared to FWI. Further, SLD images had lower variance and mean absolute error (MAE) compared to FWI of the same samples with respect to the attenuation values (reducing MAE by three times) in the tissue mimicking phantoms.