Abstract: A magnetic resonance imaging (MRI) system includes a split magnet system having a pair of MRI magnet housings separated by gap. A pair of main MRI magnets are disposed within respective MRI magnet housings. A plurality of buttress assemblies are attached to the MRI magnet housings. Some or all of the buttress assemblies are provided with removable connections to the MRI magnet housings. This allows for partial disassembly of the MRI system for improved transport and maneuverability for relocating the MRI system. The MRI system can include a gantry in the gap for supporting a radiation therapy system. Also, the removably buttress assemblies can be used for housing conduits, such as electrical and fluid conduits, between the pair of MRI magnet housings.

Abstract: A generally cylindrical set of coil windings includes primary coil windings and shield coil windings at a larger radial position than the primary coil windings, and an arcuate or annular central gap that is free of coil windings, has an axial extent of at least ten centimeters, and spans at least a 180° angular interval. Connecting conductors disposed at each edge of the central gap electrically connect selected primary and secondary coil windings. In a scanner setting, a main magnet is disposed outside of the generally cylindrical set of coil windings. In a hybrid scanner setting, an annular ring of positron emission tomography (PET) detectors is disposed in the central gap of the generally cylindrical set of coil windings.

Abstract: A generally cylindrical set of coil windings includes primary coil windings and shield coil windings at a larger radial position than the primary coil windings, and an arcuate or annular central gap that is free of coil windings, has an axial extent of at least ten centimeters, and spans at least a 180° angular interval. Connecting conductors disposed at each edge of the central gap electrically connect selected primary and secondary coil windings. In a scanner setting, a main magnet is disposed outside of the generally cylindrical set of coil windings. In a hybrid scanner setting, an annular ring of positron emission tomography (PET) detectors is disposed in the central gap of the generally cylindrical set of coil windings.

Abstract: An imaging system includes positron emission tomography (PET) detectors (30) shrouded by broadband galvanic isolation (99) and coincidence detection electronics (50, 50ob), or other radiation detectors. A magnetic resonance scanner includes a main magnet (12, 14) and magnetic field gradient assembly (20, 20?, 22, 24) configured to acquire imaging data from a magnetic resonance examination region at least partially overlapping the examination region surrounded by the PET detectors. A radio frequency coil (80, 100) has plurality of conductors (66, 166) and a radio frequency screen (88, 188, 188EB, 188F) substantially surrounding the conductors to shield the coil at the magnetic resonance frequency. The radiation detectors are outside of the radio frequency screen. Magnetic resonance-compatible radiation collimators or shielding (60, 62) containing an electrically non-conductive and non-ferromagnetic heavy atom oxide material are disposed with the radiation detectors.

Abstract: A magnetic resonance coil comprises a first set of coil elements (54, 56, 80) operatively connectable with a transmit channel (66, 74) to couple with a transmit region of sensitivity for a selected load at a magnetic field strength greater than 3 Tesla, and a second set of coil elements (52, 54, 82) operatively connectable with a receive channel (66, 74) to couple with a receive region of sensitivity for the selected load at the magnetic field strength greater than 3 Tesla. The first set of coil elements is arranged proximate to but not surrounding the transmit region of sensitivity, and the second set of coil elements is arranged proximate to but not surrounding the receive region of sensitivity. The first set of coil elements and the second set of coil elements having at least one coil element (52, 56) not in common.

Abstract: A radio frequency coil assembly includes an annular conductor (20, 22, 120) configured to support a sinusoidal electrical current distribution at a magnetic resonance frequency, and a radio frequency shield (30, 32, 34, 52, 60, 61, 130) shielding the annular conductor in at least one direction, the radio frequency shield including at least one of (i) a cylindrical shield portion (30, 60, 61, 130) surrounding a perimeter of the annular conductor, and (ii) a planar shield portion (32, 34, 52) arranged generally parallel with the annular conductor. In a magnetic resonance scanner embodiment, a magnet (10) generates a static magnetic field (B0), a magnetic field gradient system (14) is configured to superimpose selected magnetic field gradients on the static magnetic field, and said radio frequency coil assembly is arranged with the annular conductor generally transverse to the static magnetic field (B0).

Abstract: In a hybrid PET-MR system, PET detector elements (30) are added in the bore (14), in close proximity to the gradient coils (16). Fluid coolant is supplied to transfer heat from the PET detector elements (30). Thermal insulation (80) insulates the fluid coolant and the PET detector elements (30) from the gradient coils (16). In some embodiments, a first coolant path (90) is in thermal communication with the electronics, a second coolant path (92) is in thermal communication with the light detectors, and a thermal barrier (94, 96) is arranged between the first and second coolant paths such that the first and second coolant paths can be at different temperatures (Te, Td). In some embodiments a sealed heat pipe (110) is in thermal communication with a heat sink such that working fluid in the heat pipe undergoes vaporization/condensation cycling to transfer heat from the detector elements to the heat sink.

Abstract: A generally cylindrical set of coil windings (10, 30, 80) includes primary coil windings (12, 32, 82) and shield coil windings (14, 34, 84) at a larger radial position than the primary coil windings, and an arcuate or annular central gap (16, 36, 86) that is free of coil windings, has an axial extent (W) of at least ten centimeters, and spans at least a 180° angular interval. Connecting conductors (24, 44, 94) disposed at each edge of the central gap electrically connect selected primary and secondary coil windings. In a scanner setting, a main magnet (62, 64) is disposed outside of the generally cylindrical set of coil windings. In a hybrid scanner setting, an annular ring of positron emission tomography (PET) detectors (66) is disposed in the central gap of the generally cylindrical set of coil windings.

Abstract: A generally cylindrical set of coil windings includes primary coil windings and shield coil windings at a larger radial position than the primary coil windings, and an arcuate or annular central gap that is free of coil windings, has an axial extent of at least ten centimeters, and spans at least a 180° angular interval. Connecting conductors disposed at each edge of the central gap electrically connect selected primary and secondary coil windings. In a scanner setting, a main magnet is disposed outside of the generally cylindrical set of coil windings. In a hybrid scanner setting, an annular ring of positron emission tomography (PET) detectors is disposed in the central gap of the generally cylindrical set of coil windings.

Abstract: A radio frequency coil comprises an annular conductor or parallel annular conductors (22, 22c, 22d) configured to support: (i) a uniform electrical current distribution generating a first B1 field (B1,uniform) at a first magnetic resonance frequency directed out of a plane of the annular conductor or conductors; and (ii) a sinusoidal electrical current distribution generating a second B1 field (B1,sine) at a second magnetic resonance frequency directed parallel with the plane of the annular conductor or conductors. A magnetic resonance scanner comprises: a magnet (10) generating a static magnetic field (B0); a magnetic field gradient system (14) configured to superimpose selected magnetic field gradients on the static magnetic field; and said radio frequency coil including said annular conductor or parallel annular conductors (22, 22c, 22d).

Abstract: A magnetic resonance imaging (MRI) system includes a split magnet system having a pair of MRI magnet housings separated by gap. A pair of main MRI magnets are disposed within respective MRI magnet housings. A plurality of buttress assemblies are attached to the MRI magnet housings. Some or all of the buttress assemblies are provided with removable connections to the MRI magnet housings. This allows for partial disassembly of the MRI system for improved transport and maneuverability for relocating the MRI system. The MRI system can include a gantry in the gap for supporting a radiation therapy system. Also, the removably buttress assemblies can be used for housing conduits, such as electrical and fluid conduits, between the pair of MRI magnet housings.

Abstract: A positron emission tomography (PET) detector ring comprising: a radiation detector ring comprising scintillators (74) viewed by photomultiplier tubes (72); and a magnetic field shielding enclosure (83, 84) surrounding sides and a back side of the annular radiation detector ring so as to shield the photomultiplier tubes of the radiation detector ring. Secondary magnetic field shielding (76?) may also be provided, comprising a ferromagnetic material having higher magnetic permeability and lower magnetic saturation characteristics as compared with the magnetic field shielding enclosure, the second magnetic field shielding also arranged to shield the photomultiplier tubes of the radiation detector ring. The secondary magnetic field shielding may comprise a mu-metal.

Abstract: Hybrid circuitry (40, 40?, 40?) for operatively coupling a radio frequency drive signal (70) with a quadrature coil (30) is configurable in one of at least two coil modes of a group consisting of: (i) a linear I channel mode in which an I channel input port (42) is driven without driving a Q channel input port (44); (ii) a linear Q channel mode in which the Q channel input port is driven without driving the I channel input port; (iii) a quadrature mode in which both the I and Q channel input ports are driven with a selected positive phase difference; and (iv) an anti quadrature mode in which both the I and Q channel input ports are driven with a selected negative phase difference. A temporal sequence of the at least two coil modes may be determined and employed to compensate for B1 inhomogeneity.

Abstract: Gradient coil assemblies for horizontal magnetic resonance imaging systems (MRIs) and methods of their manufacture. Some embodiments may be used with open MRIs and can be used with an instrument placed in the gap of the MRI. In general, concentrations of conductors or radially oriented conductors may be moved away from the gap of the MRI so as to reduce eddy currents that may be induced in any instrument placed within the gap. Systems for directly cooling primary gradient and shield coils may be utilized and various coil supporting structures may be used to assist in coil alignment or to facilitate use of an instrument in the MRI gap.

Abstract: A magnetic resonance coil comprises a first set of coil elements (54, 56, 80) operatively connectable with a transmit channel (66, 74) to couple with a transmit region of sensitivity for a selected load at a magnetic field strength greater than 3 Tesla, and a second set of coil elements (52, 54, 82) operatively connectable with a receive channel (66, 74) to couple with a receive region of sensitivity for the selected load at the magnetic field strength greater than 3 Tesla. The first set of coil elements is arranged proximate to but not surrounding the transmit region of sensitivity, and the second set of coil elements is arranged proximate to but not surrounding the receive region of sensitivity. The first set of coil elements and the second set of coil elements having at least one coil element (52, 56) not in common.

Abstract: In a magnetic resonance scanner, a main magnet (20, 22) generates a static magnetic field at least in an examination region. A magnetic field gradient system (30, 54) selectively superimposes magnetic field gradients on the static magnetic field at least in the examination region. A magnetic resonance excitation system (36, 36?) includes at least one radio frequency coil (30, 301, 302, 303) arranged to inject radio frequency B1 fields into the examination region and at least two radio frequency amplifiers (38, 40, 40?) coupled with different input ports of the at least one radio frequency coil. A controller (66, 70) controls the magnetic resonance excitation system to produce a time varying spatial B1 field distribution in a subject (16) in the examination region that time integrates to define a spatial tip angle distribution in the subject having reduced spatial non uniformity.

Abstract: In preparation for acquiring PET image data, subject motion models are built based on physiologic signal monitoring and MR data is collected and used for improved PET imaging. The physiologic signal monitoring is also used during PET imaging, and the acquired MR data is used for prospective or retrospective gating of the PET image acquisition, or in the PET reconstruction for improved correction/imaging.

Abstract: A magnetic resonance coil includes parallel elongate conductive elements (32) arranged to define a cylinder, and end rings (34, 35) disposed at opposite ends of the parallel elongate conductive elements and oriented transverse to the parallel elongate conductive elements. The end rings are configured to support a sinusoidal 1H or other first species magnetic resonance at a magnetic field strength. The end rings and the parallel elongate conductive elements are configured to cooperatively support a second species birdcage magnetic resonance at the same magnetic field strength, the second species being different from 1H or other first species.

Abstract: An imaging system includes positron emission tomography (PET) detectors (30) shrouded by broadband galvanic isolation (99) and coincidence detection electronics (50, 50ob), or other radiation detectors. A magnetic resonance scanner includes a main magnet (12, 14) and magnetic field gradient assembly (20, 20?, 22, 24) configured to acquire imaging data from a magnetic resonance examination region at least partially overlapping the examination region surrounded by the PET detectors. A radio frequency coil (80, 100) has plurality of conductors (66, 166) and a radio frequency screen (88, 188, 188EB, 188F) substantially surrounding the conductors to shield the coil at the magnetic resonance frequency. The radiation detectors are outside of the radio frequency screen. Magnetic resonance-compatible radiation collimators or shielding (60, 62) containing an electrically non-conductive and non-ferromagnetic heavy atom oxide material are disposed with the radiation detectors.

Abstract: In a hybrid PET-MR system, PET detector elements (30) are added in the bore (14), in close proximity to the gradient coils (16). Fluid coolant is supplied to transfer heat from the PET detector elements (30). Thermal insulation (80) insulates the fluid coolant and the PET detector elements (30) from the gradient coils (16). In some embodiments, a first coolant path (90) is in thermal communication with the electronics, a second coolant path (92) is in thermal communication with the light detectors, and a thermal barrier (94, 96) is arranged between the first and second coolant paths such that the first and second coolant paths can be at different temperatures (Te, Td). In some embodiments a sealed heat pipe (110) is in thermal communication with a heat sink such that working fluid in the heat pipe undergoes vaporization/condensation cycling to transfer heat from the detector elements to the heat sink.