Full-waveform inversion with resolution proxies for in-vivo ultrasound computed tomography

We present an acoustic multi-stage full-waveform inversion (FWI) using in-vivo data of a mouse, acquired with transmission-reflection ultrasound. Our method (1) provides high-resolution images of the sound speed in soft tissue and bone, (2) significantly sharpens reflection images by using the reconstructed sound speed map as a background model, and (3) quantifies resolution lengths. The computational cost inherent to standard FWI is reduced by applying source encoding. We show that this multi-stage approach results in an aberration-corrected reflection image. The resolution lengths in the sound speed reconstruction are measured from the spread of a reconstructed point perturbation, which provides proxies for the spatial confidence levels and highlights areas where the resolution in the reflection image will benefit from the FWI background model.