Tuneable Resonance Actuators for Magnetic Resonance Elastography

Palpation, or physical manipulation of tissue to assess mechanical properties is one of the most prevalent and valuable clinical evaluations. Because physical interaction is needed, historically palpation has been limited to easily accessible surface level tissues. Magnetic resonance elastography (MRE) combines non-invasive Magnetic Resonance Imaging (MRI) with mechanically induced shear waves, producing the ability to map elasticity of soft tissues in vivo. Actuator design has been a limiting factor in MRE advancements. In this study, a mechanical resonator with adjustable resonant frequency was designed to be used in MRE applications. The designed piezoelectric actuator was fully MRI compatible, and capable of dynamically adjusting its resonant frequency. The purpose was to keep the displacement amplitude sufficiently large over a wide actuation frequency range. The outer stage of the amplifier contained movable side masses for tuning resonance frequency.