title: Electromagnetic actuator for generating variably oriented shear waves in MR elastography.
abstract: Magnetic resonance elastography (MRE) is a recently developed technique for determining the mechanical properties of biological tissue. In dynamic MRE, electromagnetic units (actuators) are widely used to generate shear waves in tissue. These actuators exploit the interaction between the static magnetic field B(0) and an annular coil supplied with alternating currents. Therefore, coil movements are restricted to selected orientations to B(0). Conventional actuators transfer this movement collinearly to B(0) into the tissue. In this study, an electromagnetic actuator was introduced that overcomes this limitation. It is demonstrated that different directions of mechanical excitation can be generated and monitored by MRE. Different spatial components of the propagation of the shear waves were determined using agarose phantoms. The technique allows maximum contrast for MRE images of objects with anisotropic strain components such as muscle tissue.
authors.affiliation: Department of Medical Informatics, Benjamin Franklin Medical Center, Free University of Berlin, Berlin, Germany. braun@medizin.fu-berlin.de
authors.forename: Juergen
authors.initials: J
authors.lastname: Braun
authors.forename: Karl
authors.initials: K
authors.lastname: Braun
authors.forename: Ingolf
authors.initials: I
authors.lastname: Sack
mesh_terms: D016880:Anisotropy; D004548:Elasticity; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008280:Magnetics / Q000295:instrumentation*; D008846:Micromanipulation / Q000295:instrumentation* / Q000379:methods; D009038:Motion; D018482:Muscle, Skeletal / Q000502:physiology*; D010812:Physical Stimulation / Q000295:instrumentation* / Q000379:methods*; D033081:Shear Strength; D014732:Vibration