Singular value decomposition based motion magnification for B-mode visualization of magnetomotive ultrasound imaging

Magnetomotive ultrasound (MMUS) is a new modality for ultrasound imaging that detects magnetic nanoparticles within tissues. To localize these nanoparticles, an external oscillating magnetic field is used to induce magnetomotion of the nanoparticles, and motion tracking algorithms are used to track the motion sources, allowing the mapping of the nanoparticle distribution. The induced magnetomotion is generally at sub-wavelength and thus not visualizable to the naked eye in conventional B-mode imaging. In this work, we introduce a singular value decomposition (SVD)-based motion magnification technique for MMUS, enabling B-mode visualization of magnetomotion in B-mode imaging. An singular value filter (SVF) is designed adaptively to extract and amplify the induced magnetomotion of the nanoparticles in MMUS imaging, offering a visually clear representation of their dynamics and the associated shear wave propagation. We evaluated the technique using simulations, phantom experiments, and in vivo data. Our motion-magnified results reveal previously unseen motions of the nanoparticles, even in the presence of undesired motion noises. This research offers a new visualization mode for MMUS imaging.