46 results about "Birdcage coil" patented technology

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.

Abstract: 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 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 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.

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 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).

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.

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 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.

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).

The invention discloses a magnetic resonance dual-mode tuned hydrogen fluorine deformation birdcage radio frequency coil. The coil comprises a coil support, a coil circuit, an adjustable capacitor support, a shielding layer, a coil sleeve, a top cover, a bottom cover, a tuning rod, a tuning linkage gear, a matching rod, a sleeve, and a ground wire terminal. The coil circuit is a racetrack-shaped flat cylindrical structure, and the tuning and radio frequency excitation positions match the dual-mode structure. According to the magnetic resonance dual-mode tuned hydrogen fluorine deformation birdcage radio frequency coil, the coil has a simple structure, and realizes hydrofluoric double resonance by using the dual mode characteristic of the deformed birdcage coil structure, and can obtain a higher sensitivity for the flat sample.