Abstract: The present invention provides a method for structurally designing that article of manufacture and a constructed and operational article of manufacture that will allow the inclusion of minimally coupled higher order/degree shim coils in any magnetic resonance apparatus. The novel system and methodology includes determining the shim coil terminal voltage without any prior or advance knowledge of the configuration of the electrical windings of the imaging gradient coil that is inducing that voltage.

Abstract: The present invention is a portable in-bore shim coil insert suitable for correcting high-degree and high-order magnetic field inhomogeneities over a limited examination zone in a magnetic resonance assembly operating above 3 T magnetic field strengths, wherein the magnetic resonance assembly includes at least a MRI magnet having an internal bore of known configuration and volume, at least one set of gradient coils, and an arrangement of radio frequency coils. The in-bore shim coil insert and corresponding method of use is able to produce higher degree and order shimming effects on-demand (i.e., the correction of at least some 3rd to 6th degree field terms or inhomogeneities) and will markedly improve the quality of in-vivo magnetic resonance spectroscopy and/or imaging of any desired anatomic site, i.e., any or all of the various organs, tissues, and systems present in the body of a living subject.

Abstract: The present invention is a portable in-bore shim coil insert suitable for correcting high-degree and high-order magnetic field inhomogeneities over a limited examination zone in a magnetic resonance assembly operating above 3 T magnetic field strengths, wherein the magnetic resonance assembly includes at least a MRI magnet having an internal bore of known configuration and volume, at least one set of gradient coils, and an arrangement of radio frequency coils. The in-bore shim coil insert and corresponding method of use is able to produce higher degree and order shimming effects on-demand (i.e., the correction of at least some 3rd to 6th degree field terms or inhomogeneities) and will markedly improve the quality of in-vivo magnetic resonance spectroscopy and/or imaging of any desired anatomic site, i.e., any or all of the various organs, tissues, and systems present in the body of a living subject.

Abstract: The instant invention provides in-vivo methods and apparatus for radiation dosimetry assessment in individuals exposed to potentially harmful radiation, based on measurements in-situ of the teeth. The in vivo dosimetry assessment methods and apparatus utilize electron paramagnetic resonance (EPR) techniques; and employ an apparatus comprising an integrated EPR spectrometer system, an ergonomic magnet and a constructed resonator structure. In various aspects, the dosimetry assessment apparatus is configured to be easily portable and withstand potentially adverse mechanical effects of transportation and deployment in the field. The apparatus also is configured with a power supply that is compatible with both conventional AC line voltages and/or other sources of power suitable for field conditions; and may be easily operated by minimally trained technicians to quickly generate a readout of estimated radiation exposure dose.

Abstract: The instant invention provides in-vivo methods and apparatus for radiation dosimetry assessment in individuals exposed to potentially harmful radiation, based on measurements in-situ of the teeth. The in vivo dosimetry assessment methods and apparatus utilize electron paramagnetic resonance (EPR) techniques; and employ an apparatus comprising an integrated EPR spectrometer system, an ergonomic magnet and a constructed resonator structure. In various aspects, the dosimetry assessment apparatus is configured to be easily portable and withstand potentially adverse mechanical effects of transportation and deployment in the field. The apparatus also is configured with a power supply that is compatible with both conventional AC line voltages and/or other sources of power suitable for field conditions; and may be easily operated by minimally trained technicians to quickly generate a readout of estimated radiation exposure dose.

Abstract: An imaging system 10 is provided comprising an imaging magnet 16 having a magnet bore 18. A plurality of passive shims 26 is positioned within the magnet bore 18. A plurality of resistive shims 46 is also positioned within the magnet bore 18. A plurality of thermometers 28 is coupled thermally to a select number of the plurality of passive shims 26 and read a passive shim temperature 36. A controller 32 is in communication with the plurality of thermometers 28 and the plurality of resistive shims 46. The controller 32 includes logic adapted to adjust control currents 40 sent to each of the plurality of resistive shims 46 in response to the resistive shim temperatures 36 received from each of the thermometers 28 such that the strength of the magnetic field and its homogeneity is maintained.

Abstract: A local head coil for an MRI system includes a passive shim assembly having ferroshims placed to reduce B0 field inhomogeneities caused by susceptibility effects in the subject being imaged. A prescan is performed with the subject in place to measure B0 field inhomogeneities and the passive shim assembly is tailored to the subject by attaching ferroshim inserts based on these measurements.

Abstract: Novel apparatus and methods for magnetic resonance imaging are disclosed which improve imaging speed and resolution as well as increase efficiency, particularly in superconducting systems. In one aspect of the invention, it has been discovered that the eddy currents and harmonics which normally interfere with MRI operations can be suppressed by the construction of an active shield about the gradient-forming components of the system. The active shield, for example, can be implemented by another set of coils, placed between the gradient coils and the cryostat in a superconducting MRI system to zero particular harmonics and prevent eddy currents in the cryostat shells. By employing a set of active secondary coils the problems associated with eddy currents induced by the gradient producing coils are substantially controlled.