Utilizing Global Time-Delay Estimation for Axial and Lateral Displacement Computation in Magnetomotive Ultrasound

Magnetic nanoparticles (MNPs) are versatile tools in biomedical applications, serving as contrast agents in magnetic resonance imaging, mediators for localized tumor heating in magnetic hyperthermia, and carriers in magnetic drug targeting (MDT). Ultrasound-based techniques such as magnetomotive ultrasound (MMUS), photoacoustics, and magneto-thermo-acoustics have been established to visualize MNP distribution. Among these, MMUS has been widely demonstrated in various in vivo applications, utilizing the displacement of MNPs induced by an alternating magnetic field to map axial displacement fields. A current research area in MNP mapping is the quantification of MNP distribution, potentially achievable via inverse MMUS, where measured displacements are used to estimate particle concentrations in a voxel. However, inverse MMUS requires comprehensive knowledge of the three-dimensional displacement vector. Conventional MMUS methods primarily compute axial displacement. In this work, we present an approach employing global time-delay estimation to calculate both axial and lateral displacements within a two-dimensional ultrasound image.Clinical relevance- Ultrasound imaging and the corresponding quantification of magnetic nanoparticle distribution offer significant potential to enhance the application of magnetic nanoparticles in localized tumor therapy and sentinel lymph node detection. These advancements can improve patient outcomes during treatment and help prevent tumor metastasis.