arXiv subjects

Benjamin N. Frey

Publications and source records attributed to Benjamin N. Frey.

2 recordsLinked to original sources

arXiv2026

Lens-Aware Differentiable Beamforming for In Vivo Distributed Aberration Correction with Curvilinear Transducers

This work extends ultrasound autofocusing via common midpoint phase error optimization to support curvilinear array geometries. Iterative model-based aberration correction via local sound speed estimation is performed by accounting for refraction caused by the transducer lens by using a differentiable bent-ray tracing approach. Model validation is performed in silico, using calibrated sound speed phantoms, and on in vivo human liver images. This work represents the first large-scale in vivo validation of our distributed aberration-correction method on 321 acquisitions from 81 high-BMI human liver subjects. In acquired images with anechoic regions, average contrast and CNR improved by $1.42 \pm 1.63$ dB (+18.4%), and $0.09 \pm 0.14$ (+10.3%), respectively. An average improvement was also observed across multiple image quality metrics: speckle brightness (+20.1%), coherence factor (+13.1%), lag-one coherence (+2.6%), common-midpoint correlation coefficient (+0.7%), and common-midpoint phase error (-9.1%, lower is better). All metric improvements were statistically significant. Additionally, a significant qualitative improvement in target structure and visibility was observed. These results demonstrate the potential for future clinical distributed aberration correction techniques using ultrasound autofocusing.

physics.med-ph↗

arXiv2025

Ultrasound Autofocusing: Common Midpoint Phase Error Optimization via Differentiable Beamforming

In ultrasound imaging, propagation of an acoustic wavefront through heterogeneous media causes phase aberrations that degrade the coherence of the reflected wavefront, leading to reduced image resolution and contrast. Adaptive imaging techniques attempt to correct this phase aberration and restore coherence, leading to improved focusing of the image. We propose an autofocusing paradigm for aberration correction in ultrasound imaging by fitting an acoustic velocity field to pressure measurements, via optimization of the common midpoint phase error (CMPE), using a straight-ray wave propagation model for beamforming in diffusely scattering media. We show that CMPE induced by heterogeneous acoustic velocity is a robust measure of phase aberration that can be used for acoustic autofocusing. CMPE is optimized iteratively using a differentiable beamforming approach to simultaneously improve the image focus while estimating the acoustic velocity field of the interrogated medium. The approach relies solely on wavefield measurements using a straight-ray integral solution of the two-way time-of-flight without explicit numerical time-stepping models of wave propagation. We demonstrate method performance through in silico simulations, in vitro phantom measurements, and in vivo mammalian models, showing practical applications in distributed aberration quantification, correction, and velocity estimation for medical ultrasound autofocusing.

physics.med-ph↗