Contactless methods of measuring mechanical response in deep orthopedic tissue

Open Access
Author:
Kiger, Shane
Area of Honors:
Mechanical Engineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Dr. Daniel Cortes, Thesis Supervisor
  • Dr. Jacqueline O'Connor, Honors Advisor
Keywords:
  • biomechanics
  • imaging
  • mechanical response
  • magnetic resonance elastography
  • orthopedic tissue
  • mechanical stiffness
Abstract:
Magnetic Resonance Elastography has been utilized to determine the mechanical stiffness in biological structures of a human anatomy. Through this testing, results can be assessed to determine a normal or healthy range for the functionality of these different biological structures. Mechanical stiffness that is misaligned with normal baseline numbers can often be an indicator of a patient suffering from pathology of that same body part. With the necessity of wave propagation in the entity of interest, functionality of this procedure has been limited to regions permitting direct vibrational contact. The purpose of this study is to assess the feasibility of wave motion by means of remote induction. Deep orthopedic structures are composed of matrices that hold an ionic charge. Movement of those ions in a cross-directional magnetic field could present the capability to induce shear wave motion through remote means. This will be assessed through the utilization of phantom gels mimicking the ionic properties of orthopedic tissue that would allow for an electromagnetic induction of wavelike motion. The same principle in theory could be used to medically assess deeper regions of the body protected by bone and other anatomical structures. In testing, gels were subjected to movement parallel to and orthogonal to the direction of the magnetic field. The differences observed in the motion wavelength were on a magnitude of 4-5% which, with the resolution of the images, could potentially be attributed to precision error.