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Abstract:
A method of nuclear magnetic resonance (NMR) imaging is proposed for the rapid detection of oscillatory motion of spins or charged particles to generate shear waves or oscillating electrical currents to induce alternating magnetic fields to the object being imaged, subjected to a fast train of radio-frequency (RF) pulses to induce within the sample a steady-state NMR signal. A scan using an NMR imaging system is carried out with a RF repetition time (TR) matched to the externally imposed oscillatory motion. Small oscillatory displacements of spins in combination with imaging gradients or oscillating magnetic fields related to charge motion generating alternating spin phase dispersions during the rf pulse train disturb the steady-state magnetization. Depending on the amount of spin-phase dispersion, the amplitude and phase of the NMR signals are modulated, generating a brightness-modulation of the reconstructed phase and amplitude images revealing mechanical or electrical properties of the object, such as stiffness or electrical impedance.
