Abstract: An imaging method comprises: acquiring magnetic resonance data of a subject using a magnetic resonance component (30, 30?) disposed with the subject; acquiring nuclear imaging data of the subject with the magnetic resonance component disposed with the subject; determining a position of the magnetic resonance component respective to a frame of reference of the nuclear imaging data; and reconstructing the nuclear imaging data (60) to generate a nuclear image (62) of at least a portion of the subject. The reconstructing includes adjusting at least one of the nuclear imaging data and the nuclear image based on a density map (46) of the magnetic resonance component and the determined position of the magnetic resonance component respective to the frame of reference of the nuclear imaging data to correct the nuclear image for radiation absorption by the magnetic resonance component.

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.

Abstract: A transverse magnetic field gradient coil includes a set of primary coil loops (62) defining an operative coil end (66) and a distal coil end (68). The set of primary coil loops are configured to generate a magnetic field gradient in a selected region asymmetrically disposed relatively closer to the operative coil end and relatively further from the distal coil end. A set of shield coil loops (64) are disposed outside the set of primary coil loops and are configured to substantially shield the set of primary coil loops. Two or more current jumps (70) are disposed at the distal end. Each current jump electrically connects an incomplete loop of the set of primary coil loops with an incomplete loop of the set of shield coil loops.

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 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: 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: 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: In a magnetic resonance imaging system (10), a main magnet (20) generates a substantially uniform main magnetic field (B0) through an examination region (14). An imaging subject (16) generates inhomogeneities in the main magnetic field (B0). One or more shim coils are positioned adjacent a gradient coil (26). The gradient coil (26) is driven in halves by first and second power sources (28, 30) which have slightly dissimilar power characteristics which induce an inductive coupling between the shim coil (60) and the gradient coil (26). The shim coil (60) is designed to produce a desired magnetic field, such that the inductive coupling of the shim coils (60) to the gradient coil (26) is substantially minimized while the inhomogeneities in the main magnetic field (B0) caused by the imaging subject are corrected based on prespecified spatial characteristics.

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 MRI apparatus includes a main magnet (12) for generating a main magnetic field in an examination region, a plurality of gradient magnets (16) for generating magnetic field gradients in the main magnetic field, a radio frequency coil (22) for transmitting radio frequency signals into the examination region and exciting magnetic resonance in a subject disposed therein, and a radio frequency coil for receiving the magnetic resonance signals from the subject. The MRI apparatus also includes subject support (52) for supporting the subject, a position controller (60) for controlling the position of the subject support within the examination region, and a position encoder (53) for directly measuring the position of the subject support.

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.