Abstract: An ultra-high field radio-frequency (RF) transmit/receive apparatus radio-frequency (RF) transmit/receive apparatus for magnetic resonance (MR) systems, may include: a dipole-array based volume coil (2) with a plurality of straight dipole antennas (3); at least three circular conducting rings (4, 5, 6) radial surrounding the dipole-array based volume coil (2), the at least three circular conducting rings (4, 5, 6) being substantially parallel with each other, having a plurality of ports (9, 10) for receiving a set of quadrature drive signals, the RF coil apparatus further comprising at least two independent transmit/receive (T/R) RF channels (11, 12, 13, 14) for driving the dipole-array based volume coil (2) and the at least three circular conducting rings (4, 5, 6).

Abstract: An ultra-high field radio-frequency (RF) transmit/receive apparatus radio-frequency (RF) transmit/receive apparatus for magnetic resonance (MR) systems, may include: a dipole-array based volume coil (2) with a plurality of straight dipole antennas (3); at least three circular conducting rings (4, 5, 6) radial surrounding the dipole-array based volume coil (2), the at least three circular conducting rings (4, 5, 6) being substantially parallel with each other, having a plurality of ports (9, 10) for receiving a set of quadrature drive signals, the RF coil apparatus further comprising at least two independent transmit/receive (T/R) RF channels (11, 12, 13, 14) for driving the dipole-array based volume coil (2) and the at least three circular conducting rings (4, 5, 6).

Abstract: A magnetic resonance (MR) system includes a volume-type radio-frequency (RF) coil assembly having a volume coil with a plurality of ports and a ring coil with a plurality of ports (p?) and which is situated about the volume-type coil. At least one controller is configured to selectively control a first transmit/receive (T/R) radio frequency (RF) channel to generate an output including RF quadrature signals to drive the volume-type coil and to selectively control a second T/R RF channel to generate an output including RF quadrature signals to drive the ring coil.

Abstract: A router (60), for use with magnetic resonance systems (10), selectively routes unique excitation signals, generated by a multi-channel radio-frequency (RF) amplifier, over transmission lines (Tx) to any one of a plurality of connection panels (66) which each accepts at least one RF coil assembly having multiple coil elements (20). Each connection panel (66) includes transceiver ports (68) for connecting at least one conductor (22,24) of the coil elements (20) to a corresponding transceiver channel (T/R). The router (60) selectively routes magnetic resonance signals received by the conductors (22,24) from the transceiver channels (T/R) to a multi-channel RF receiver (41). The coin elements may carry sine-mode currents or uniform currents.

Abstract: A magnetic resonance system (1) includes at least one radio frequency (RF) transmit coil (6), an RF transmitter (34), an anthropometric unit (28), and an adaptive SAR unit (40). The at least one radio frequency (RF) transmit coil (6) transmits measured RF power to excite and manipulate magnetic resonance in tissues of a subject (57) in an examination region. The RF transmitter (34) controls the amount of transmitted RF power based on a specific absorption rate (SAR) for an imaging sequence. The anthropometric unit (28) determines a mass of a portion of the subject which receives the transmitted RF power based on a determined total mass. The adaptive SAR unit (40) adjusts a selected scan sequence based on the SAR parameters determined from the measured transmitted RF power and a measured reflected power, achieved IB|+I field, the mass of the portion of the subject which receives the transmitted RF power and applicable SAR parameter models stored in a SAR reference unit (46).

Abstract: A magnetic resonance (MR) system may include: a volume-type radio-frequency (RF) coil assembly having a volume coil with a plurality of ports and a ring coil with a plurality of ports (??) and which is situated about the volume-type coil; and at least one controller configured to selectively control a first transmit/receive (T/R) radio frequency (RF) channel to generate an output including RF quadrature signals to drive the volume-type coil and to selectively control a second T/R RF channel to generate an output including RF quadrature signals to drive the ring coil.

Abstract: Coil elements (18) generate a B1 excitation field in an examination region (14), which B1 excitation field is distorted by patient loading (e.g., wavelength effects). Passive shimming elements (22, 24) are disposed between the coil elements and the subject in order to improve the B1 field uniformity. In one embodiment, passive shimming elements include one or more dielectric rods (55) disposed below the subject which generate no substantial MR proton signal and which have a permittivity of at least 100 and preferably greater than 500. In another embodiment, tubes (24) adjacent each coil element are supplied with a dielectric liquid, a thickness of the dielectric liquid between the coil element and the subject adjusting a phase of the B1 field generated by the coil element. Active B1 shimming may be combined with passive shimming elements (22, 24) to effect an improved RF field homogeneity result.

Abstract: A magnetic resonance system (1) includes at least one radio frequency (RF) transmit coil (6), an RF transmitter (34), an anthropometric unit (28), and an adaptive SAR unit (40). The at least one radio frequency (RF) transmit coil (6) transmits measured RF power to excite and manipulate magnetic resonance in tissues of a subject (57) in an examination region. The RF transmitter (34) controls the amount of transmitted RF power based on a specific absorption rate (SAR) for an imaging sequence. The anthropometric unit (28) determines a mass of a portion of the subject which receives the transmitted RF power based on a determined total mass. The adaptive SAR unit (40) adjusts a selected scan sequence based on the SAR parameters determined from the measured transmitted RF power and a measured reflected power, achieved IB|+I field, the mass of the portion of the subject which receives the transmitted RF power and applicable SAR parameter models stored in a SAR reference unit (46).

Abstract: Coil elements (18) generate a B1 excitation field in an examination region (14), which B1 excitation field is distorted by patient loading (e.g., wavelength effects). Passive shimming elements (22, 24) are disposed between the coil elements and the subject in order to improve the B1 field uniformity. In one embodiment, passive shimming elements include one or more dielectric rods (55) disposed below the subject which generate no substantial MR proton signal and which have a permittivity of at least 100 and preferably greater than 500. In another embodiment, tubes (24) adjacent each coil element are supplied with a dielectric liquid, a thickness of the dielectric liquid between the coil element and the subject adjusting a phase of the B1 field generated by the coil element. Active B1 shimming may be combined with passive shimming elements (22, 24) to effect an improved RF field homogeneity result.

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 router (60), for use with magnetic resonance systems (10), selectively routes unique excitation signals, generated by a multi-channel radio-frequency (RF) amplifier, over transmission lines (Tx) to any one of a plurality of connection panels (66) which each accepts at least one RF coil assembly having multiple coil elements (20). Each connection panel (66) includes transceiver ports (68) for connecting at least one conductor (22,24) of the coil elements (20) to a corresponding transceiver channel (T/R). The router (60) selectively routes magnetic resonance signals received by the conductors (22,24) from the transceiver channels (T/R) to a multi-channel RF receiver (41). The coin elements may carry sine-mode currents or uniform currents.

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: 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: 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: 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: 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: A device performs MR imaging of a body (7) placed in a stationary and substantially homogeneous main magnetic field, with an RF transmit antenna (6) for radiating RF pulses towards the body (7), which RF transmit antenna (6) has different resonance modes. In order to improve image uniformity in high field MR imaging, the device (1) is arranged to determine the size and/or the aspect ratio of the body (7), and to acquire an MR image of the body (7) by an imaging sequence including RF pulses. The phases and amplitudes of the different resonance modes of the RF transmit antenna (6) excited during irradiation of the RF pulses are controlled on the basis of the size and/or aspect ratio of the body (7).

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: A radio frequency coil for magnetic resonance imaging or spectroscopy includes a plurality of generally parallel conductive members (70) surrounding a region of interest (14). One or more end members (72, 74) are disposed generally transverse to the plurality of parallel conductive members. A generally cylindrical radio frequency shield (32) surrounds the plurality of generally parallel conductive members. Switchable circuitry (80, 80?) selectably has: (i) a first switched configuration (90, 90?) in which the conductive members are operatively connected with the one or more end members; and (ii) a second switched configuration (92, 92?) in which the conductive members are operatively connected with the radio frequency shield. The radio frequency coil operates in a birdcage resonance mode in the first switched configuration and operates in a TEM resonance mode in the second switched configuration.