摘要:
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.
摘要:
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. The first and second sets of coil elements define transmit and receive regions of sensitivity for the selected load at the magnetic field strength greater than 3 Tesla that are substantially similar.
摘要:
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.
摘要:
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.
摘要:
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. The first and second sets of coil elements define transmit and receive regions of sensitivity for the selected load at the magnetic field strength greater than 3 Tesla that are substantially similar.
摘要:
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).
摘要:
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.
摘要:
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.
摘要:
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.
摘要:
A pair of quadrature radio frequency coils (32, 34) disposed adjacent an imaging region (10) are typically loaded differently due to factors such as subject geometry, subject mass, and a relative distance from the subject. A tip angle adjustment circuit (50) monitors a combined tip angle adjacent a mid-plane of the examination region, such as by analyzing delivered and reflected power to each of the coils. An adjustment circuit (54) adjusts relative RF power or amplitude to produce a selected, combined tip angle in the examination region.