BME.10 – Torsional Actuator for Ultra High Field Magnetic Resonance Elastography

• Ghena Akkawi
• Haley Calderon
• Abdullah Fouad
• Vishnupriya Jadeja
• Jenny Kim

Magnetic Resonance Elastography (MRE) is a technique that combines Magnetic Resonance Imaging with a device extension (actuator) that sends out vibrations through tissue and is used to produce a heat map of the tissue stiffness. Since different tissue types have varying stiffness quantities, MRE provides researchers with a noninvasive way to study the viscoelastic properties of human muscle tissue without having to take a biopsy. Previously, there have been attempts to model vibrations with a linear actuator that sends out uniaxial waves through the length of the tissue, but wave attenuation was observed in the tissue sample, making visualization of the tissue properties difficult. Converting the actuator to a system that would produce torsional waves would address the issues with wave attenuation in the linear system since the waves would travel radially inward, reducing attenuation and allowing the user to visualize the anisotropic stresses of the tissue. We have designed a system with two piezos connected via a coupler; our aim is to torsionally displace the tissue sample by hundreds of microns at a frequency of 300-3000 Hz. We are going to use a scanning laser doppler vibrometer (SLDV) which utilizes the doppler effect to measure the vibrational frequency and the torsional displacement. While a relatively new field, MRE has the potential to quickly, effectively, and noninvasively biopsy individual tissues. Currently, MRE is predominantly used on skeletal muscle tissue, but as smaller and more sophisticated actuators are designed, the opportunity to target other tissue types becomes more realistic. In the ideal future, patients will no longer have to suffer the pain of physical biopsies nor must wait weeks to hear back with results.