General Electric Company

The United States of America As Represented by the Secretary of

Ge Medical Systems Global Technology Company, LLC

General Electric Corporation Gmbh

Daniel Joseph Schaefer

Robert Michael Vavrek

Graeme Colin McKinnon

Joseph K Maier

Kenneth W Belt

Daniel Joseph Weyers

Thomas G McFarland

Dewain Anthony Purgill

Steven Christopher Davis

Hammond G Reynolds

Timothy William Skloss

Roman I Dachniwskyj

Robert G Turner

Christopher C Myers

Robert W Newman

A system and method including an apparatus for use in electrically loading RF coils of an MRI system is disclosed. The apparatus includes a polymer interdispersed with an electrically conductive additive such that the apparatus provides the necessary electrical loading of the RF coils for testing and calibration of the MRI system but is free of liquid. Furthermore, the apparatus is capable of providing the requisite electrical load in high magnet magnetic fields without introducing image distortion as a result of standing waves within the apparatus.

System and method of electrically loading radio-frequency coils using conductive polymers

A method for decreasing gradient field pulse sequence duration for a magnetic resonance imaging system, the method comprising: establishing an allowable gradient field strength for an axis of a plurality of axes for a field of view; applying a weighting factor associated with each axis of the plurality of axes; establishing a slew rate responsive to a selected axis of the plurality of axes that exhibits a largest gradient field strength in light of the weighting factor and the field of view; and operating the plurality of axes at the largest gradient field strength.

Gradient coil apparatus for magnetic resonance imaging

Vibration of the magnet assembly in a MRI system perturbs the magnetic field and adversely affects the images produced by the system. The perturbation of the magnetic field can be sensed by an apparatus having a source which emits a first signal that is reflected off the magnet assembly. A receiver detects a second signal formed by the reflected portion of the first signal. The first and second signals are processed to produce an output signal representing movement of the electromagnet and thus variation of the magnetic field. That output signal can be used by to components of the magnetic resonance imaging system to compensate for the effects that the vibration has on the images.

Method and apparatus for measuring vibration of a magnetic resonance imaging system

A local coil assembly includes an RF coil disposed inside a cylindrical form and a pair of z-axis gradient coils wound around the outside of the cylindrical form. First and second pairs of gradient coils are mounted on opposite sides and extend radially outward from the cylindrical form. These pairs of gradient coils produce a gradient field perpendicular to the z-axis with minimal effect on the operation of the RF coil.

Local transverse gradient coil

A compact local gradient coil is combined with a local RF coil to provide lower powered, higher strength gradient fields and faster gradient response as is useful in magnetic resonance imaging. Interference between the RF coil and gradient coil is minimized by placement of the gradient coil external to the RF coil and by gradient coils that are axially symmetric and/or have conductors substantially orthogonal to the RF coil conductors. Acoustic noise in these smaller, stronger coils is reduced with ports cut into the coil forms.

Local gradient coil

An NMR imaging system includes a prescan procedure in which the RF transmit power level is calibrated to produce an optimal, uniform RF field. Pulse sequences are conducted at a series of RF power levels and from the resulting acquired NMR data the power level which produces the most uniform signal across the extent of the subject being imaged is determined.

RF power calibration for an NMR scanner

There is provided a phantom for measuring a performance parameter of a nuclear magnetic resonance scanner capable of acquiring NMR data from a study object. The phantom is made up of a housing composed of a substantially non-NMR-active material, and positionable in use within a radio-frequency coil forming part of an NMR scanner. The phantom further includes a first medium disposed within the housing to load the radio frequency coil in a manner similar to that of a patient. The NMR properties of the medium are further selected such that an NMR signal, if any, produced by the medium occurs at a time other than when a performance parameter of said NMR scanner is measured. In the preferred embodiment, the phantom comprises two concentrically disposed cylinders of different diameters and a pair of end plates fastened to opposite ends of the cylinders. The first medium is disposed within the volume defined between the side walls of the cylinders and the end plates. A second medium is disposed within the volume defined within the innermost cylinder and generates the NMR test signals.

Phantom for performance evaluation of a nuclear magnetic resonance

An apparatus and method are disclosed which provide signals corresponding to physiological motion of an imaging slice in an MR system for use in synchronizing acquisition of MR data with movement of the slice. The signals are generated by initiating an incident signal of a frequency .omega. which interacts with the imaging slice and returns a reflected signal of a frequency .omega.. By mixing the incident and reflected signal, a baseband signal is generated which is indicative of changes in the phase and magnitude relationships between the signals. Because changes in the phase and magnitude relationships between the signals are related in an approximately linear manner to movement of the imaging slice, the baseband signal provides an indication of movement of the imaging slice of sufficient quality to serve as an accurate triggering signal to synchronize acquistion of MR data with movement of the imaging slice.

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Waukesha, WI, United States of America

Daniel Joseph Schaefer