Wave-Equation Migration Velocity Analysis for Multistatic Synthetic Aperture Ultrasound

TL;DR

This paper introduces wave-equation migration velocity analysis (WEMVA) for multistatic synthetic aperture ultrasound, improving image quality by reconstructing sound speed profiles to correct aberrations.

Contribution

It is the first application of WEMVA to medical ultrasound imaging, demonstrating significant enhancements in image resolution and contrast.

Findings

Point target resolution improved from 1.22±1.01 mm to 0.32±0.07 mm.

Lesion contrast increased from 3.05 to 4.39 dB.

Dramatic image quality improvements shown in phantom experiments.

Abstract

Sound speed heterogeneities can create aberrations in B-mode ultrasound images by inducing tissue-dependent delays and diffractive effects that conventional beamforming does not incorporate. By using the Fourier split-step method to simulate pressure fields in heterogenous sound speed media, reverse-time migration (RTM) can reconstruct the B-mode image by cross-correlating transmitted and received pressure fields. As a result, RTM is differentiable with respect to sound speed. This enables the reconstruction of the sound speed profile that minimizes the aberration in the B-mode image. In seismic imaging, this form of diffraction tomography, known as wave-equation migration velocity analysis, can roughly be understood as a type of full-waveform inversion (FWI) that acts in the image domain rather than errors in the received channel data. This is the first work applying WEMVA to medical pulse-echo ultrasound imaging. Phantom experiments show dramatic improvements in image quality with measured improvements in point target resolution from 1.22$\pm$1.01 to 0.32$\pm$0.07 mm and lesion contrast from 3.05 to 4.39 dB.