Interface devices for use with intracavity probes for high field strength magnetic resonance systems
First Claim
1. An interface device for interfacing an intracavity probe with a magnetic resonance system having a receive cycle and a transmit cycle of operation, said intracavity probe having a coil loop and a pair of output cables terminating in a cable connector therefor for connecting said coil loop to said interface device, said interface device comprising:
- (a) an interface device connector to which said intracavity probe is connectable via said cable connector thereof;
(b) a phase shifting network linked to said interface device connector, said phase shifting network having a first and a second sub-network to which a first and a second of said pair of output cables are joined, respectively, when said cable and said interface device connectors of said intracavity probe and said interface device are connected, each of said output cables connected at the other end thereof across a drive capacitor in said coil loop and having an electrical length of SL+n(λ
/4) wherein SL is a supplemental length whose reactance is of a same magnitude as a reactance of said drive capacitor corresponding thereto, n is an odd integer, and λ
is a wavelength of the operating frequency of said magnetic resonance system; and
(c) a pair of PIN diodes of which a first PIN diode is connected across an output of said first sub-network and a second PIN diode is connected across an output of said second sub-network such that an electrical length of each of said first and said second sub-networks from said interface device connector to said PIN diode corresponding thereto is λ
/4;
wherein when said cable and said interface device connectors of said intracavity probe and said interface device are connected, said phase shifting network enables said coil loop (i) during said receive cycle when said PIN diodes are reverse biased to be coupled through said output cables to a probe input port of said magnetic resonance system thus allowing magnetic resonance signals received from each of said output cables to be constructively combined and routed to said probe input port, and (ii) during said transmit cycle when said PIN diodes are forward biased to be decoupled from a transmit field of said magnetic resonance system via a combined electrical length of SL +n(λ
/2) of each of said output cables and said sub-network corresponding thereto.
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Accused Products
Abstract
An interface device enables an intracavity probe to be used with a magnetic resonance (MR) system for the purpose of obtaining images or spectra of a region of interest within a cavity of a patient. The probe includes a shaft, a balloon at one end thereof, and a coil loop within the balloon. The coil loop preferably includes two drive capacitors and a tuning capacitor, all of which in series. A junction node between the drive capacitors serves as a ground for electrically balancing the coil loop. Diametrically opposite the junction node, the tuning capacitor enables the coil loop to resonate at the operating frequency of the MR system. Across each drive capacitor is connected an output cable having an electrical length of SL+n(λ/4). The output cables terminate in a plug that is used to connect the coil loop to the interface device.
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Citations
20 Claims
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1. An interface device for interfacing an intracavity probe with a magnetic resonance system having a receive cycle and a transmit cycle of operation, said intracavity probe having a coil loop and a pair of output cables terminating in a cable connector therefor for connecting said coil loop to said interface device, said interface device comprising:
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(a) an interface device connector to which said intracavity probe is connectable via said cable connector thereof; (b) a phase shifting network linked to said interface device connector, said phase shifting network having a first and a second sub-network to which a first and a second of said pair of output cables are joined, respectively, when said cable and said interface device connectors of said intracavity probe and said interface device are connected, each of said output cables connected at the other end thereof across a drive capacitor in said coil loop and having an electrical length of SL+n(λ
/4) wherein SL is a supplemental length whose reactance is of a same magnitude as a reactance of said drive capacitor corresponding thereto, n is an odd integer, and λ
is a wavelength of the operating frequency of said magnetic resonance system; and(c) a pair of PIN diodes of which a first PIN diode is connected across an output of said first sub-network and a second PIN diode is connected across an output of said second sub-network such that an electrical length of each of said first and said second sub-networks from said interface device connector to said PIN diode corresponding thereto is λ
/4;wherein when said cable and said interface device connectors of said intracavity probe and said interface device are connected, said phase shifting network enables said coil loop (i) during said receive cycle when said PIN diodes are reverse biased to be coupled through said output cables to a probe input port of said magnetic resonance system thus allowing magnetic resonance signals received from each of said output cables to be constructively combined and routed to said probe input port, and (ii) during said transmit cycle when said PIN diodes are forward biased to be decoupled from a transmit field of said magnetic resonance system via a combined electrical length of SL +n(λ
/2) of each of said output cables and said sub-network corresponding thereto. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An interface device for interfacing an intracavity probe and a coil system with a magnetic resonance system having a receive cycle and a transmit cycle of operation, said intracavity probe having a coil loop and a pair of output cables terminating in a cable connector therefor for connecting said coil loop to said interface device, said interface device comprising:
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(a) an interface device connector to which said intracavity probe is connectable via said cable connector thereof; (b) a phase shifting network linked to said interface device connector, said phase shifting network having a first and a second sub-network to which a first and a second of said pair of output cables are joined, respectively, when said cable and said interface device connectors of said intracavity probe and said interface device are connected, each of said output cables connected at the other end thereof across a drive capacitor in said coil loop and having an electrical length of SL+n(λ
/4) wherein SL is a supplemental length whose reactance is of a same magnitude as a reactance of said drive capacitor corresponding thereto, n is an odd integer, and λ
is a wavelength of the operating frequency of said magnetic resonance system;(c) a pair of PIN diodes of which a first PIN diode is connected across an output of said first sub-network and a second PIN diode is connected across an output of said second sub-network such that an electrical length of each of said first and said second sub-networks from said interface device connector to said PIN diode corresponding thereto is λ
/4;wherein when said cable and said interface device connectors of said intracavity probe and said interface device are connected, said phase shifting network enables said coil loop (i) during said receive cycle when said PIN diodes are reverse biased to be coupled through said output cables to a probe input port of said magnetic resonance system thus allowing magnetic resonance signals received from each of said output cables to be constructively combined for output to said probe input port, and (ii) during said transmit cycle when said PIN diodes are forward biased to be decoupled from a transmit field of said magnetic resonance system via a combined electrical length of SL +n(λ
/2) of each of said output cables and said sub-network corresponding thereto; and(d) an array interface circuit for electrically interconnecting said coil system and said magnetic resonance system. - View Dependent Claims (8)
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9. An interface device for interfacing an intracavity probe with a magnetic resonance system having a receive cycle and a transmit cycle of operation, said intracavity probe having a coil loop and a pair of output cables terminating in a connector therefor for connecting said coil loop to said interface device, each of said output cables connected at the other end thereof across a drive capacitor in said coil loop and having an electrical length of SL +n(λ
- /4) wherein SL is a supplemental length whose reactance is of a same magnitude as a reactance of said drive capacitor corresponding thereto, n is an odd integer, and λ
is a wavelength of the operating frequency of said magnetic resonance system, said interface device comprising;(a) an input to which said intracavity probe is connectable via said connector thereof; (b) a phase shifting network linked to said input, said phase shifting network having a first and a second sub-network for joining a first and a second of said output cables, respectively, when said connector of said intracavity probe and said input of said interface device are connected, said first and said second sub-networks having electrical lengths of λ
/A and - λ
/4, respectively, through which to impart a phase shift of λ
/4 and - λ
/4 on magnetic resonance signals received, respectively, from said first and said second output cables; and(c) a pair of PIN diodes of which a first PIN diode is connected across an output of said first sub-network and a second PIN diode is connected across an output of said second sub-network thus demarcating the electrical lengths of λ
/4 and - λ
/4 of said first and said second sub-networks, respectively, from said input of said interface device to said PIN diode corresponding thereto, the PIN diodes being capable of being biased by the magnetic resonance system;wherein when said connector of said intracavity probe and said input of said interface device are connected, said phase shifting network enables; (i) during said receive cycle when said PIN diodes are reverse biased, said coil loop to be coupled through said output cables to a probe input port of said magnetic resonance system thus allowing said magnetic resonance signals received from each of said output cables to be constructively combined and routed to said probe input port; and (ii) during said transmit cycle when said PIN diodes are forward biased, said coil loop to be decoupled from a transmit field of said magnetic resonance system due to an effective electrical length of SL that arises (A) in the combination of the electrical length SL +n(λ
/4) of said first output cable with the electrical length λ
/4 of said first sub-network and (B) in the combination of the electrical length SL +n(λ
/4) of said second output cable (3e) with the electrical length —
λ
/4 of said second sub-network. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
- /4) wherein SL is a supplemental length whose reactance is of a same magnitude as a reactance of said drive capacitor corresponding thereto, n is an odd integer, and λ
Specification