48 results about "Birdcage coil" patented technology

A tunable radio frequency birdcage coil (26, 34) has an improved tuning range for use with a magnetic resonance apparatus. The coil includes a pair of end ring conductors (60, 62) which are connected by a plurality of spaced leg conductors (L2, L4, . . ., L26) to form a generally cylindrical volume. Both the end rings and the leg conductors contain reactive elements, preferably capacitors (C2, C4, . . ., C124). The radio frequency coil also includes a pair of tuning rings (100, 120) for tuning the reactive elements (C2, C4, . . ., C124), which each include a non-conductive support cylinder (110, 130) and a plurality of tuning bands (120, 122, . . ., 142 and 150, 152, . . ., 172) which extend axially along the outer surface of the support cylinder (110, 130). The tuning rings (100, 120) are rotated or translated with respect to the leg conductors (L2, L4, . . ., L26) in order to vary capacitance and inductance of the coil (26, 34) to tune the (26, 34) coil to the desired resonant frequency.

A coil interface allows a neurovascular coil system to be coupled to a magnetic resonance (MR) system. The neurovascular coil system has an array of coils including a birdcage coil, a spine coil, and at least one neck coil, with the MR system being equipped with a number of receivers. The coil interface includes a plurality of input ports, a plurality of output ports, and an interface circuit. The plurality of input ports are for coupling to the coils of the neurovascular coil system, and the plurality of output ports for coupling to the receivers of the MR system. The interface circuit enables the input ports and output ports to be selectively interconnected, and thereby enables the neurovascular coil system to be selectively operated in (I) a neurovascular mode; (II) a high resolution brain mode; (III) a high speed brain mode; and (IV) a volume neck mode.

A high resolution NMR probe having two or more resonators, an inner resonator which is closely coupled to a sample and is used to stimulate and receive a response from one nuclear species, and an outer resonator to induce transitions in another nuclear species, wherein the resonators may be provided with cooling capability and may be made of superconducting material, and wherein the inner resonator may be a saddle coil or a birdcage coil with capability of being tuned, and wherein the outer resonator may be one or more spiral wound saddle coil.

A birdcage coil for use with a magnetic resonance (MR) system comprises a first ring at one thereof, a second ring at the other end thereof, and a plurality of rods electrically interconnecting the first and second rings. The first ring is electrically conductive and has a first diameter. The second ring is electrically conductive and has a second diameter. The rods and first and second rings are configured to form about the birdcage coil a plurality of partially-overlapped primary resonant substructures. Each primary resonant substructure includes two of the rods and the corresponding sections of the first and second rings interconnecting them.

A switchable birdcage coil functioning as a transmitter coil and a separate RF surface coil functioning as the receiver coil are utilize in NMR and MRI apparatus. To prevent the switchable birdcage coil from absorbing energy by coupling to the receiver coil or by absorbing power from the RF field produced by the precessing nuclear spins, one or more of the reactive elements of the birdcage coil are switched from a normal reactive impedance state to a high impedance state. The high impedance state is formed by switchably combining the reactive element with a complementary reactive element thereby forming parallel resonant high impedance circuit that is tuned to resonate at the NMR frequency.

A birdcage coil for use with a magnetic resonance (MR) system comprises a first ring at one thereof, a second ring at the other end thereof, and a plurality of rods electrically interconnecting the first and second rings. The first ring is electrically conductive and has a first diameter. The second ring is electrically conductive and has a second diameter. The rods and first and second rings are configured to form about the birdcage coil a plurality of partially-overlapped primary resonant substructures. Each primary resonant substructure includes two of the rods and the corresponding sections of the first and second rings interconnecting them.

A radio frequency coil assembly for use in a magnetic resonance system comprises a set of conductors for detecting magnetic resonance signals in three orthogonal planes and capacitors for resonating the set of conductors at a predetermined frequency. A conductor of the set of conductors is placed on each edge of a cube-shaped volume and the capacitors are placed on each conductor of the set of conductors such that each conductor has substantially equal effective capacitance.A four element band pass birdcage coil comprises two square end ring segments, each end ring segment comprising four sides of equal length, and four rungs of length equal to a side of the end ring segment, and wherein four rungs join in respective corners of the end ring segments.

The invention relates to a birdcage coil for a magnetic resonance imaging system and a tuning method thereof. The birdcage coil comprises an upper annular conductor, a lower annular conductor and a plurality of linear conductors which are distributed on a cylindrical surface, wherein the linear conductors are connected between the upper annular conductor and the lower annular conductor. A plurality of capacitors are connected in series in the upper annular conductor and the lower annular conductor. The whole or a part of the linear conductor is flexibly bendable and deformable. The distance between the upper annular conductor and the lower annular conductor is changed when the degree of bending deformation of the linear conductor is adjusted so that the resonant frequency of the birdcage coil is changed. The resonant frequency is adjusted by changing the position of a debugging ring. Thus, an expensive adjustable capacitor device is replaced so as to reduce the cost of the birdcage coil. The birdcage coil can be easily debugged at the installation site of the magnetic resonance system. The structure of the whole birdcage coil is adjusted synchronously and a large tuning range is achieved. The distribution of coil current and the uniformity of an RF magnetic field inside the coil are not influenced. The birdcage coil is stable in mechanical structure and can withstand high voltage.

A radio frequency (RF) birdcage coil includes a first distributed capacitance end ring, a second distributed capacitance end ring, and a plurality of rungs connected between the first and second end rings, wherein at least one of the first and second distributed capacitance end rings includes a substrate having a first side and a second side, a first plurality of conductors formed on the first side, a second plurality of conductors formed on the second side, and an insulating material deposited on the first side such that the insulating material substantially covers the first plurality of conductors.

A radio frequency coil (30, 30', 120, 120') for a magnetic resonance imaging system (10, 10'') includes a birdcage section (34, 122, 122') having a plurality of parallel spaced apart conductors (46, 130, 130') and one or more cross or end conductors (48, 132, 144', 154, 156) aligned generally transverse to the spaced apart conductors (46, 130, 130'), and a TEM section (32, 32', 32'', 124, 124') having a plurality of parallel spaced apart conductors (40, 40', 140) and a radio frequency screen (42, 142, 144, 144'). The birdcage section (34, 122, 122') and the TEM section (32, 32', 32'', 124, 124') resonate at a birdcage resonant frequency and a TEM resonant frequency, respectively. The birdcage section (34, 122,122') and the TEM section (32, 32', 32'', 124, 124') are relatively disposed with the parallel spaced apart conductors of each section aligned and define a subject receiving region.

An apparatus for MRI having an RF birdcage coil and an RF shield is disclosed. The RF birdcage coil includes a coil axis, an end ring portion disposed about the axis, and a plurality of legs disposed parallel to the axis and in signal communication with the end ring portion. The RF shield is disposed about the coil and is in signal communication therewith. The shield includes a cylindrical conductive sheet having first and second ends, and a plurality of sets of discontinuous slots disposed about the cylindrical sheet and running between the first and second ends, wherein a region of discontinuity within a set of the slots is aligned with the end ring portion.

MR receive (or reception) coil arrangements are disclosed which comprise at least one MR receive coil or coil element or coil system (9) which can be tuned and / or detuned in relation to an MR frequency, and which further comprise a transmission line (7) for electrically connecting the MR receive coil or coil element or coil system (9) with an MR receiver (10). Especially such MR receive coil arrangements are disclosed which are not provided for being stationarily (or permanently) installed or built in an examination zone of an MR imaging or examination system or apparatus (MRI system), like a whole-body coil system of such an MRI system, but which are mobile, like e.g. interventional or invasive devices, like catheters, or surface coils, e.g. in the form of (especially flexible) pads which are positioned on a surface of an examination object for examining a region of interest, or volume coils like birdcage coils for enclosing and examining a volume of interest. Finally, an MR imaging or examination system (MRI system) comprising such an MR receive coil arrangement is disclosed.

A magnetic resonance radio frequency transmission device (140) for generating and applying a radio frequency excitation field B1 for the purpose of magnetic resonance examination comprises a birdcage coil (144) and a plurality of M radio frequency amplifier units for providing radio frequency power at a magnetic resonance frequency to the birdcage coil (144) via a plurality of M activation ports (158) selected out of the plurality of N activation ports (158). In an operational state of the birdcage coil (144) each radio frequency amplifier unit (142) is electrically connected and is arranged in close proximity to an activation port (158). Among the plurality of M radio frequency amplifier units (142), there is established a fixed relationship of adjustable phase angles (phi) of the magnetic resonance radio frequency power provided by the plurality of M radio frequency amplifier units (142); a method of generating and applying a radio frequency excitation field B for the purpose of magnetic resonance examination, using such magnetic resonance radio frequency transmission device (140); and a magnetic resonance imaging system (110) configured for acquiring magnetic resonance images of at least a portion of a subject of interest (120), comprising such magnetic resonance radio frequency transmission device (140).

A birdcage coil (10) for a magnetic resonance imaging device includes a plurality of rungs (12) coupled to a distal edge (15) of each of two endrings (16). The endrings (16) comprise a plurality of ring segments (18) that are separated by sets of capacitors (20, 22, 24). The rungs (12) are coupled to the endrings (16) by connector portions (14), which create a gap between the endrings (16) and the rungs (12). Additionally, the rungs (12) can be positioned over the capacitors (20, 22, 24), and the connector portions (14) can be shaped to offset the position of the rungs (12) relative to the ring segments (16) to which they are coupled to achieve a desire rung position relative to the capacitors (20, 22, 24).

An RF volume resonator system is disclosed comprising a multi-port RF volume resonator (40, 50; 60), like e.g. a TEM volume coil or TEM resonator, or a birdcage coil, all of those especially in the form of a local coil like a head coil, or a whole body coil, and a plurality of transmit and / or receive channels (T / RCh1, . . . T / RCh8) for operating the multi-port RF volume resonator for transmitting RF excitation signals and / or for receiving MR relaxation signals into / from an examination object or a part thereof. By the individual selection of each port (P1, . . . P8) and the appropriate amplitude and / or frequency and / or phase and / or pulse shapes of the RF transmit signals according to the physical properties of an examination object, a resonant RF mode within the examination object with an improved homogeneity can be excited by the RF resonator.

A coil for magnetic resonance imaging operates in a transmit mode with multiple loops locked together in a phase relationship like a birdcage coil to provide a uniform transmission field, but in a receive mode like a phased array coil, each coil operating independently to produce a separate signal for reception by the MRI machine. Phasing of the coil during transmit mode is provided by a ring resonator controllably coupled to the loops. Controllable coupling is provided by a series of current limiting elements interposed between the resonant ring and the loops of the coil.

The invention relates to a multi-channel (e.g. quadrature) MRI transmit system in which RF power amplifiers having different power capabilities are used in different transmit channels. This results in reduced system costs, due to the avoidance of an unused excess of RF power capability when the power demand for obtaining a homogeneous B1-field (RF shimming) is asymmetric and the asymmetry is qualitatively the same for different imaging applications. The multi-channel transmit unit may also comprise a commutator which enables to selectively connect each RF power amplifier to each drive port of transmit coil arrangement (e.g. a birdcage coil).

A magnetic resonance radio frequency transmission device (140) for generating and applying a radio frequency excitation field B1 for the purpose of magnetic resonance examination comprises a birdcage coil (144) and a plurality of M radio frequency amplifier units for providing radio frequency power at a magnetic resonance frequency to the birdcage coil (144) via a plurality of M activation ports (158) selected out of the plurality of N activation ports (158). In an operational state of the birdcage coil (144) each radio frequency amplifier unit (142) is electrically connected and is arranged in close proximity to an activation port (158). Among the plurality of M radio frequency amplifier units (142), there is established a fixed relationship of adjustable phase angles (φ) of the magnetic resonance radio frequency power provided by the plurality of M radio frequency amplifier units (142); a method of generating and applying a radio frequency excitation field B for the purpose of magnetic resonance examination, using such magnetic resonance radio frequency transmission device (140); and a magnetic resonance imaging system (110) configured for acquiring magnetic resonance images of at least a portion of a subject of interest (120), comprising such magnetic resonance radio frequency transmission device (140).

The embodiment of the invention discloses a magnetic resonance multi-core radio frequency coil device, a control method and a magnetic resonance imaging system. The magnetic resonance multi-core radio frequency coil device comprises a first birdcage coil and a second birdcage coil which are coaxially nested, the first birdcage coil comprises four first end rings arranged in the axial direction and a plurality of first leg structures connected with the four first end rings. The second birdcage coil comprises two second end rings arranged in the axial direction and a plurality of second leg structures connected with the two first end rings; the first birdcage coil is used for transmitting and receiving radio frequency energy of frequencies corresponding to three different nuclides; the second birdcage coil is used for transmitting and receiving radio frequency energy of a frequency corresponding to one kind of nuclide; and nuclides corresponding to the first birdcage coil and the second birdcage coil are different. According to the technical scheme provided by the embodiment of the invention, uniform excitation and acquisition of the signals with the frequency required by four-nuclide magnetic resonance imaging can be realized at the same time, and the accuracy of four-nuclide imaging is improved.

A radio frequency coil is disclosed that is suitable for use with a magnetic resonance imaging apparatus. The radio frequency coil comprises first and second conductive loops connected electrically to each other by a plurality of conductive rungs. The conductive rungs each include a section that is relatively thin that will result in less attenuation to a radiation beam than other thicker sections of the rungs. Insulating regions are also disposed in areas of the radio frequency coil that are bound by adjacent rungs and the conductive loops. Portions of the insulating regions can be configured to provide a substantially similar amount of attenuation to the radiation beam as the relatively thin sections of the conductive rungs.

The present invention is directed to an elliptical birdcage coil which reduces time and effort upon manufacturing and production cost, with less variations in performance. There is provided a high frequency coil unit made up of the elliptical birdcage coil having plural capacitors arranged at least on either of the ring conductors and the rung conductors, the capacitance of the plural capacitors being uniform with respect to each conductor type on which the capacitors are placed. In this elliptical birdcage coil, a value of inductance and arrangement of the ring conductors and the rung conductors are determined in such a manner that the capacitance of the capacitors becomes identical with respect to each conductor type on which the capacitors are arranged.

A radio frequency (RF) antenna device (40) for applying an RF field to an examination space (16) of a magnetic resonance (MR) imaging system (10), the RF antenna device (40) comprising a plurality of rungs (42, 44) arranged substantially parallel and in an azimuthally substantially equally spaced relationship along an outside of a virtual cylinder (50) with a cylinder axis (52) running parallel to main directions of extension (48); at least one transversal antenna member (54) electromagnetically coupled to at least one rung (42, 44) of the plurality of rungs (42, 44), wherein the at least one transversal antenna member (54) is arranged within a plane substantially perpendicular to the main directions of extension (48) of the plurality of rungs (42, 44); and a plurality of RF circuitries (62, 64, 66), wherein at least one RF circuitry (62, 64, 66) is provided for each rung (42, 44) of the plurality of rungs (42, 44) for mutual decoupling and for individually feeding RF power into and for the at least one transversal antenna member (54) for individually feeding RF power into.

The present invention provides a radio frequency (RF) shield device (124) for a magnetic resonance (MR) examination system (110), whereby the RF shield device (124) comprises a first shield (250) and a second shield (252), the first shield (250) and the second shield (252) are arranged with a common center axis (118), the first shield (250) has a shield structure (254) different from a shield structure (254) of the second shield (252), and the first shield (250) and the second shield (252) are designed in accordance with different modes of operation of a RF coil device (140). The present invention also provides a radio frequency (RF) coil device (140) for a magnetic resonance (MR) examination system (110), whereby the RF coil device (140) comprises a first coil (200) and in a second coil (202), the first coil (200) and the second coil (202) are provided as birdcage coils, the first coil (200) and the second coil (202) are arranged with a common center axis (118), the first coil (200) and the second coil (202) have rungs (204), which are arranged non-parallel to the center axis (118) of the RF coil device (140), the first coil (200) has a coil structure (210) different from a coil structure (210) of the second coil (202), and the first coil (200) and the second coil (202) are switchable to be active for different modes of operation. The present invention further provides a magnetic resonance (MR) imaging system (110), comprising such a RF coil device (140) and / or such a RF shield device (124).