Magnetomotive ultrasound

Last revised by Daniel J Bell on 20 Jun 2021

Magnetomotive ultrasound (MMUS) is an emerging medical imaging modality, which utilizes the discrete tissue vibration caused by superparamagnetic iron oxide (SPIO) nanoparticles under an external magnetic field. 


If an external time-varying magnetic field is applied (e.g. using an electromagnet on the body surface) SPIO nanoparticles within tissues are displaced, which generates a small amount of movement in adjacent tissues. With sufficiently sensitive, frequency-specific ultrasound transducers this movement can be detected and the signal selectively amplified 1

Practical points

While currently used microbubble ultrasonic contrast agents are exclusively intravascular, SPIOs can readily exit the vasculature and can be therefore used to target a broader range of tissues and cellular markers. As a result magnetomotive ultrasound can be theoretically utilized for a variety of molecular imaging applications 1

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