Ultrasound Aberration Correction based on Local Speed-of-Sound Map Estimation

TL;DR

This paper introduces a local speed-of-sound map-based delay correction method for ultrasound beamforming, significantly improving image resolution and accuracy over traditional global SoS assumptions.

Contribution

It presents a novel direct delay correction approach using 2D spatial SoS maps, enhancing resolution and localization accuracy in ultrasound imaging.

Findings

Achieves 22-29% resolution improvement in tissue samples.

Accurately images tissue structures down to a tenth of a wavelength.

Outperforms global SoS assumptions in localization accuracy.

Abstract

For beamforming ultrasound (US) signals, typically a spatially constant speed-of-sound (SoS) is assumed to calculate delays. As SoS in tissue may vary relatively largely, this approximation may cause wavefront aberrations, thus degrading effective imaging resolution. In the literature, corrections have been proposed based on unidirectional SoS estimation or computationally-expensive a posteriori phase rectification. In this paper we demonstrate a direct delay correction approach for US beamforming, by leveraging 2D spatial SoS distribution estimates from plane-wave imaging. We show both in simulations and with ex vivo measurements that resolutions close to the wavelength limit can be achieved using our proposed local SoS-adaptive beamforming, yielding a lateral resolution improvement of 22% to 29% on tissue samples with up to 3% SoS-contrast (45m/s). We verify that our method accurately images absolute positions of tissue structures down to sub-pixel resolution of a tenth of a wavelength, whereas a global SoS assumption leads to artifactual localizations.