Fiber optic telemetry for switched-mode current-source amplifier in magnetic resonance imaging (MRI)

Patent metadata

Field	Value
Publication number	US-9536423-B2
Application number	US-201314053305-A
Country	US
Kind code	B2
Filing date	Oct 14, 2013
Priority date	Mar 31, 2013
Publication date	Jan 3, 2017
Grant date	Jan 3, 2017

Abstract

Example systems, apparatus, circuits, and other embodiments described herein concern acquiring telemetry data from an MR system and providing the telemetry data via fiber optic cable. One example apparatus includes a telemetry signal acquisition element (e.g., circuit, circuit component) that is configured to acquire a telemetry signal from a component in the MR apparatus. The component may be, for example, a transmit coil or an on-coil amplifier. The example apparatus also includes a fiber optic cable that is configured to carry an output signal from the MR apparatus through a field produced by the MR apparatus. The example apparatus also includes a telemetry signal output element that is configured to produce the output signal from the telemetry signal and to transmit the output signal via the fiber optic cable.

First claim

What is claimed is:

1. A telemetry apparatus for use with a magnetic resonance (MR) apparatus, comprising:
a telemetry signal acquisition element configured to acquire a telemetry signal from a component in the MR apparatus;
a fiber optic cable configured to carry an output signal through a field produced by the MR apparatus;
a telemetry signal output element configured to produce the output signal from the telemetry signal and to transmit the output signal via the fiber optic cable;
a control logic configured to produce a control signal as a function of the output signal and to provide the control signal to the MR apparatus; and
the control signal being an on/off signal, an increase voltage signal, a decrease voltage signal, an increase current signal, a decrease current signal, an increase power signal, a decrease power signal, an increase frequency signal, a decrease frequency signal, an increase pulse time signal, or a decrease pulse time signal.

2. The telemetry apparatus of claim 1 , the component in the MR apparatus being a transmit coil.

3. The telemetry apparatus of claim 1 , the telemetry signal acquisition element being a multiplexer.

4. The telemetry apparatus of claim 1 , the telemetry signal acquisition element being a voltage detector, a current detector, a power detector, a frequency detector, or a pulse time detector.

5. The telemetry apparatus of claim 1 , the MR apparatus being a magnetic resonance imaging (MRI) apparatus or a magnetic resonance spectroscopy (MRS) apparatus.

6. The telemetry apparatus of claim 1 , the telemetry signal being a digital signal.

7. The telemetry apparatus of claim 6 , the digital signal being a slope comparator output, a module inhibit signal, or a pulse width modulation signal.

8. The telemetry apparatus of claim 6 , the telemetry signal output element being configured to produce the output signal from the digital signal without modulating the telemetry signal.

9. The telemetry apparatus of claim 1 , the telemetry signal output element being configured to transmit two or more output signals via the fiber optic cable.

10. A telemetry for use with a magnetic resonance (MR) apparatus, comprising:
a telemetry signal acquisition element configured to acquire a telemetry signal from a component in the MR apparatus;
a fiber optic cable configured to carry an output signal through a field produced by the MR apparatus;
telemetry signal output element configured to produce the output signal from the telemetry signal and to transmit the output signal via the fiber optic cable; and
the component in the MR apparatus being a transmit coil configured with an on-coil amplifier;
the on-coil amplifier being a switched mode amplifier, a switched-mode current-source amplifier, or a current-mode class-D (CMCD) amplifier.

11. A telemetry apparatus for use with a magnetic resonance (MR) apparatus, comprising:
a telemetry signal acquisition element configured to acquire a telemetry signal from a component in the MR apparatus;
a fiber optic cable configured to carry an output signal through a field produced by the MR apparatus;
a telemetry signal output element configured to produce the output signal from the telemetry signal and to transmit the output signal via the fiber optic cable;
a control logic configured to produce a control signal as a function on the output signal and to provide the control signal to the MR apparatus; and
the control signal being a pulse width modulation signal, a sigma delta modulation signal, or a pulse train optimization signal.

12. A telemetry apparatus for use with a magnetic resonance (MR) apparatus, comprising:
a telemetry signal acquisition element configured to acquire a telemetry signal from a component in the MR apparatus;
a fiber optic cable configured to carry an output signal through a field produced by the MR apparatus;
a telemetry signal output element configured to produce the output signal from the telemetry signal to transmit the output signal via the fiber optic cable; and
the output signal being an analog signal.

13. The telemetry apparatus of claim 12 , the analog signal being an envelope set point signal, an output envelope signal, or an error amplifier output signal.

14. The telemetry apparatus of claim 12 , the analog signal having a frequency of less than 2 MHz.

15. The telemetry apparatus of claim 12 , the telemetry signal output element being configured with a sigma-delta modulator configured to produce a modulated analog signal from the analog signal by performing sigma-delta modulation on the analog signal,
the telemetry signal output element being configured to produce the output signal from the modulated analog signal.

16. The telemetry apparatus of claim 15 , the sigma-delta modulator being configured with a variable frequency relaxation oscillator configured as a digital-to-analog converter.

17. A method, comprising:
acquiring, in real-time, a telemetry signal from a transmit coil in a magnetic resonance imaging (MRI) apparatus;
upon determining that the telemetry signal is a digital signal, producing an output digital signal representing the telemetry signal and placing the output digital signal on a fiber optic cable connected to the transmit coil; and
upon determining that the telemetry signal is an analog signal, producing a modulated analog signal from the analog signal using sigma-delta modulation, and placing the modulated analog signal on the fiber optic cable.

18. The method of claim 17 , comprising providing an indication of whether the transmit coil is operating as desired based, at least in part, on the telemetry signal.

19. The method of claim 18 , comprising determining a real-time control signal from the output digital signal or the modulated analog signal and selectively providing the real-time control signal to the MRI apparatus.

20. The method of claim 19 , where the real-time control signal is configured to alter the operation of an element of the transmit coil that produced the telemetry signal.

21. The method of claim 20 , comprising selectively controlling whether the telemetry signal is acquired and selectively controlling whether the output signal or the modulated analog signal are placed on the fiber optic cable as a function of a set point of a radio frequency (RF) input envelope associated with the transmit coil.

22. An MRI apparatus, comprising:
a digital controller;
a set of LC-switched-mode transmit coils operably connected to the digital controller, where a member of the set of LC switched-mode coils includes a field effect transistor based switched-mode current-source amplifier and a transmit coil that are controlled, at least in part, by a signal from the digital controller; and
a telemetry circuit configured to acquire a telemetry signal from the member of the set of LC-switched-mode coils and to provide the telemetry signal, via a fiber optic cable, to a region located outside a Faraday cage bounding the MRI apparatus.

Assignees

• Univ Case Western Reserve

Inventors

• Griswold Mark
• Twieg Michael

Classifications

• G01R33/56366

  Perfusion imaging · CPC title

• A61B5/0017

  transmitting optical signals · CPC title

• G08C23/06 Primary

  through light guides, e.g. optical fibres · CPC title

• G01R33/3692

  involving signal transmission without using electrically conductive connections, e.g. wireless communication or optical communication of the MR signal or an auxiliary signal other than the MR signal · CPC title

• G01R33/56

  Image enhancement or correction, e.g. subtraction or averaging techniques {, e.g. improvement of signal-to-noise ratio and resolution} · CPC title