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 radio frequency coil for magnetic resonance imaging includes an active coil member (70, 701, 170, 270) that defines an imaging volume. The active coil member has a first open end (74) with a first cross-sectional dimension (dactive). A shield coil member (72, 721, 722, 723, 724, 725, 172, 1722, 272) substantially surrounds the active coil member. The shield coil member has a constricted open end (88) arranged proximate to the first open end of the active coil member with a constricted cross-sectional dimension (dconst) that is less than the cross-sectional dimension (dShieid) of the shield coil member. In some embodiments, the radio frequency coil further includes an outer shield coil member (100) that is substantially larger than the shield coil member (72, 721, 722, 723, 724, 725, 172, 1722, 272), and surrounds both the active coil member and the shield coil member.

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 B inhomogeneity.

Abstract: The invention relates to a device for 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 invention proposes the device (1) being 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 means of an imaging sequence comprising RF pulses, wherein 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: 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 transverse electromagnetic (TEM) coil is provided. The TEM coil includes an electrically conductive shell and an end plate disposed at a first end of the shell. The TEM coil also includes a plurality of TEM elements disposed within the shell, the plurality of TEM elements being shorter than the shell.

Abstract: A radio frequency coil system (38) for magnetic resonance imaging includes a plurality of parallel spaced apart rungs (60) which each includes rung capacitors (68). An end cap (64) is disposed at a closed end (66) of the coil system (38). An RF shield (62) is connected to the end cap (64) and surrounds the rungs (60), extending in a direction substantially parallel to rungs (60). The RF coil system (38) may be used as birdcage, TEM, hybrid, combination birdcage and TEM, or other.

Abstract: In a transmit apparatus, a multi-channel radio frequency transmitter (30, 46) includes a plurality of transmit elements (32) defining at least two independently operable transmit channels. A transmit configuration selector (54) determines a selected transmit configuration (60) specifying amplitude and phase applied to each transmit channel to generate a B1 field in a corresponding selected region (90) of a subject (38) coupled with the radio frequency transmitter. The transmit configuration selector determines the selected transmit configuration based on B1 mapping (58) of the subject and a B1 field quality assessment employing at least two different B1 field quality measures.

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.

Abstract: A radio frequency coil for magnetic resonance imaging includes an active coil member (70, 701, 170, 270) that defines an imaging volume. The active coil member has a first open end (74) with a first cross-sectional dimension (dactive). A shield coil member (72, 721, 722, 723, 724, 725, 172, 1722, 272) substantially surrounds the active coil member. The shield coil member has a constricted open end (88) arranged proximate to the first open end of the active coil member with a constricted cross-sectional dimension (dconst) that is less than the cross-sectional dimension (dShieid) of the shield coil member In some embodiments, the radio frequency coil further includes an outer shield coil member (100) that is substantially larger than the shield coil member (72, 721, 722, 723, 724, 725, 172, 1722, 272), and surrounds both the active coil member and the shield coil member.

Abstract: Multi-slice magnetic resonance imaging of a region of interest of an imaging subject (16) is performed using a radio frequency coil (40) arranged to generate a B1 magnetic field in the region of interest. One or more processors (44, 82, 88, 110) determine a B1 field value for each slice that is representative of the B1 field over a selected area of the slice, accounting for subject effects on the BI field, and determine an adjusted per-slice radio frequency excitation for each slice that adjusts the B1 field value for the slice to a selected value. A magnetic resonance imaging system (10, 44, 46, 50, 52) acquires magnetic resonance imaging data for each slice using the adjusted per-slice radio frequency excitation for that slice. A reconstruction processor (58) reconstructs the acquired magnetic resonance imaging data into a reconstructed image representation.

Abstract: A magnetic resonance imaging system (10) utilizes an ultra-short RF body coil (36). The ultra-short body coil (36) is shorter than the mechanical equivalent birdcage coil by at least a factor of two. Such coil provides equivalent (Bt) magnetic field-uniformity, while conforming to SAR limitations.

Abstract: A radio frequency coil system (38) for magnetic resonance imaging includes a plurality of parallel spaced apart rungs (60) which each includes rung capacitors (68). An end cap (64) is disposed at a closed end (66) of the coil system (38). An RF shield (62) is connected to the end cap (64) and surrounds the rungs (60), extending in a direction substantially parallel to rungs (60). The RF coil system (38) may be used as birdcage, TEM, hybrid, combination birdcage and TEM, or other.

Abstract: An MRI apparatus is provided. The apparatus includes a main magnet for generating a main magnetic field in an examination region, a plurality of gradient coils for generating gradient fields within the main field, an RF transmit coil for transmitting RF signals into the examination region and exciting magnetic resonance in a subject disposed therein in accordance with a plurality of imaging parameters, the transmitted RF signals having a SAR associated therewith, and a SAR processor for maintaining the transmitted RF signals below a prescribed SAR level.

Abstract: A transverse electromagnetic (TEM) coil is provided. The TEM coil includes an electrically conductive shell and an end plate disposed at a first end of the shell. The TEM coil also includes a plurality of TEM elements disposed within the shell, the plurality of TEM elements being shorter than the shell.

Abstract: Multi-slice magnetic resonance imaging of a region of interest of an imaging subject (16) is performed using a radio frequency coil (40) arranged to generate a B1 magnetic field in the region of interest. One or more processors (44, 82, 88, 110) determine a B1 field value for each slice that is representative of the B1 field over a selected area of the slice, accounting for subject effects on the BI field, and determine an adjusted per-slice radio frequency excitation for each slice that adjusts the B1 field value for the slice to a selected value. A magnetic resonance imaging system (10, 44, 46, 50, 52) acquires magnetic resonance imaging data for each slice using the adjusted per-slice radio frequency excitation for that slice. A reconstruction processor (58) reconstructs the acquired magnetic resonance imaging data into a reconstructed image representation.

Abstract: An MRI apparatus is provided. The apparatus includes a main magnet for generating a main magnetic field in an examination region, a plurality of gradient coils for generating gradient fields within the main field, an RF transmit coil for transmitting RF signals into the examination region and exciting magnetic resonance in a subject disposed therein in accordance with a plurality of imaging parameters, the transmitted RF signals having a SAR associated therewith, and a SAR processor for maintaining the transmitted RF signals below a prescribed SAR level.