Using memristor devices as switches for MRI RF coils

Patent metadata

Field	Value
Publication number	US-9417299-B2
Application number	US-201013376615-A
Country	US
Kind code	B2
Filing date	May 17, 2010
Priority date	Jun 19, 2009
Publication date	Aug 16, 2016
Grant date	Aug 16, 2016

Abstract

A radiofrequency (RF) coil assembly ( 18,18 ′) for use in a magnetic resonance system ( 10 ) includes a radiofrequency coil ( 42 ) and a plurality of memory resistive elements ( 46,56,62,72 ) which each retains a selected resistive state after a control signal is removed. A detune circuit ( 44 ), part of the radiofrequency coil assembly, includes a memory resistive element ( 46 ) which switches the radiofrequency coil between a tuned and detuned state. Connected between the radiofrequency coil and a pre-amplifier ( 52 ), a blanking circuit ( 54 ) includes a memory resistive element ( 56 ) to short circuit an input of the pre-amplifier. A multiplexing circuit ( 60 ) includes a plurality of memory resistive elements ( 62 ) to selectively couple the selected outputs of the radiofrequency coils to a receiver ( 26 ). A biasing circuit ( 27 ) generates the control signal to set the memory resistive elements ( 46,56 ) to a first resistive state during a transmit mode and to a second resistive state during a receive mode magnetic resonance system.

First claim

Having thus described the preferred embodiments, the invention is now claimed to be:

1. A radiofrequency (RF) coil assembly configured for use in a magnetic resonance system, including:
a preamplifier;
a transmit radiofrequency coil;
a receive radiofrequency coil; and
a memory resistive element which retains a selected resistive state after a control signal is removed, wherein the memory resistive element functions as a switch and is connected between the receive radiofrequency coil and the pre-amplifier of the magnetic resonance system.

2. The RF coil assembly according to claim 1 , further including:
a biasing circuit which generates a control signal in order to set the memory resistive element into one of a plurality of resistive states.

3. The RF coil assembly according to claim 2 , wherein the memory resistive element is part of a detuning circuit which switches the receive radiofrequency coil between a tuned state, tuned to a resonance frequency, and a detuned state.

4. The RF coil assembly according to claim 3 , wherein the detune circuit includes:
the memory resistive element in series with the receive radiofrequency coil, the resistance of the memory resistive element being switched between highly resistive and highly conductive states by the generated control signal.

5. The RF coil assembly according to claim 3 , wherein the detune circuit includes:
a resonant trap, the memory resistive element being switched by the generated control signal in order to connect the resonant trap in series with the receive radiofrequency coil.

6. The RF coil assembly according to claim 2 , further including:
a blanking circuit connected to the receive radiofrequency coil and the pre-amplifier, where the blanking circuit includes the memory resistive element which when biased into a conductive state, is configured, in order to short circuit an input into the pre-amplifier from the receive radiofrequency coil.

7. The RF coil assembly according to claim 6 , wherein the memory resistive element is connected in parallel between the receive radiofrequency coil and the pre-amplifier.

8. The RF coil assembly according to claim 1 further including:
a biasing circuit which generates the control signal in order to set the memory resistive element into a first resistive state when the RF coil assembly is in a transmit mode and into a second resistive state when the RF coil assembly is in a receive mode.

9. The RF coil assembly according to claim 1 , further including:
a multiplexing circuit including a plurality of memory resistive elements configured to couple to the receive radiofrequency coil at an output of the RF coil assembly.

10. The RF coil assembly according to claim 1 , further including:
a memory constructed with a plurality of the memory resistive elements that function as switches and are configured to store resistive state information.

11. The RF coil assembly according to claim 1 , further including at least one of:
a detuning circuit configured with the memory resistive element that is configured to block a selected RF frequency induced on the receive radiofrequency coil;
a blanking circuit configured with the memory resistive element that is configured to selectively short circuit an input of the pre-amplifier; and
a multiplexing circuit configured with a plurality of the memory resistive elements that are configured to selectively couple the output of the receive radiofrequency coil onto downstream processing circuitry.

12. The RF coil assembly according to claim 2 , wherein the memory resistive element includes a mersister which is biased into a resistive state by a DC bias and holds said resistive state when the DC bias is removed.

13. The RF coil assembly according to claim 1 , further including:
circuitry which measures a resistance of the memory resistive element.

14. A magnetic resonance system, including:
a magnet which generates a static magnetic field in an examination region;
at least one RF coil assembly according to claim 1 configured to acquire magnetic resonance data from the examination region;
a transmitter connected to the at least one RF coil assembly;
an RF receiver connected with the at least one RF coil assembly; and
a scan controller configured to control the RF transmitter and the RF receiver along with a control circuit that is configured to generate the control signal;
wherein the control circuit is configured to adjust the resistive state of the memory resistive element;
a data processor which processes magnetic resonance data from the RF receiver in order to produce one of magnetic resonance imaging data or magnetic resonance spectroscopy data; and
a display which displays results of the performed magnetic resonance signal processing.

15. A magnetic resonance method, including:
transmitting RF signals by a transmit radiofrequency (RF) coil in order to induce magnetic resonance signals in an examination region;
receiving the magnetic resonance signals with a receive radiofrequency (RF) coil; and
setting, in a magnetic resonance system, a resistive state of at least one memory resistive element, from a plurality of memory resistive elements, in order to short an input into a pre-amplifier in the magnetic resonance system, that amplifies the received magnetic resonance signals during transmission of the RF signals, wherein the at least one memory resistive element of the plurality of memory resistive elements functions as a switch and performs at least one of:
detuning the receive RF coil that receives the magnetic resonance signals during transmission of the RF signals, and
selectively coupling one of a plurality of outputs onto downstream processing.

16. The method according to claim 15 , wherein setting the resistive state of the at least one memory resistive element includes:
applying a bias voltage of a first polarity to the at least one memory resistive element of the plurality of memory resistive elements in order to increase its resistance;
stopping applying the first polarity bias voltage at a first selected resistance, the at least one memory resistive element of the plurality of memory resistive elements holding the first selected resistance after the step of applying the biasing voltage has stopped;
applying a bias voltage of a second polarity to the at least one memory resistive element of the plurality of memory resistive elements in order to decrease its resistance; and
stopping applying the second polarity bias voltage at a second selected resistance, the at least one memory resistive element of the plurality of memory resistive elements holding the second selected resistance after the step of applying the biasing voltage has stopped.

17. The method according to claim 15 , wherein the at least one memory resistive element of the plurality of memory resistive elements is connected in series with the receive RF coil and connects the receive RF coil with a resonant trap, the steps of setting the resistive state including:
before transmitting the RF signals, applying a first polarity bias voltage to the at least one memory resistive element of the plurality of memory resistive elements, which biases the at least one memory resistive element of the plurality of memory resistive elements into a first resistive state and then stopping the step of applying the first polarity bias voltage such that the at least one memory resistive element of the plurality of memory resistive elements holds the first resistive state; and
before receiving the magnetic resonance signals, applying a second polarity b

Assignees

• Reykowski Arne
• Koninklijke Philips Nv

Inventors

• Reykowski Arne

Classifications

• G01R33/3415 Primary

  comprising arrays of sub-coils {, i.e. phased-array coils with flexible receiver channels} · CPC title

• G01R33/3664

  Switching for purposes other than coil coupling or decoupling, e.g. switching between a phased array mode and a quadrature mode, switching between surface coil modes of different geometrical shapes, switching from a whole body reception coil to a local reception coil or switching for automatic coil selection in moving table MR or for changing the field-of-view (G01R33/3671 takes precedence) · CPC title

• G01R33/3657

  Decoupling of multiple RF coils wherein the multiple RF coils do not have the same function in MR, e.g. decoupling of a transmission coil from a receive coil · CPC title