Abstract: A metamaterial (MTM) slab for a Magnetic Resonance Imaging (MRI) system passively interacts with a field generated by a transmit device to improve homogeneity of the field, specific absorption rate, and/or strength of the field. The MTM slab may also be connected to RF receive circuitry at one or more ports to act as a receiver for the MRI. The MTM slab may comprise a first layer generally defining a surface and a second layer offset from the surface generally defined by the first layer, the first layer and the second layer interacting to form a 2D transmission line supporting radio frequency (RF) current along the surface in a first direction and in a second direction transverse to the first direction, the first layer and the second layer being connected via linking capacitors.

Abstract: A liner for a bore of an MRI scanner having a magnetic field. The liner comprises: plural conductors extending circumferentially within a liner region of the bore; circumferential impedances on the plural conductors; and radial impedances connecting the plural conductors to a radially outer conductive structure.

Abstract: Systems and methods for closed-loop ultrasound imaging-based control are described herein. An example system includes an ultrasound transducer, and a controller operably coupled to the ultrasound transducer. The controller includes a processor and memory, the memory having computer-executable instructions stored thereon. The controller is configured to receive an ultrasound imaging signal associated with a subject's muscular activity from the ultrasound transducer; process the ultrasound imaging signal to obtain a feedback signal; and control a device interfacing with the subject based on the feedback signal.

Abstract: A liner for a bore of a waveguide is provided. The liner as an aperture passing through it and is formed of a metamaterial that has a relative electrical permittivity that is negative and near zero. When the liner is installed in the waveguide, it lowers the cutoff frequency of the waveguide while allowing the waveguide to remain hollow. This liner can be used in the bore of an MRI machine to lower the cutoff frequency of the bore of the MRI machine to allow the MRI machine to operate using waves having a lower frequency that if the liner was not used.