Resonator with adjustable capacitance for medical device

• US 20080290958A1
• Filed: 07/29/2008
• Published: 11/27/2008
• Est. Priority Date: 11/09/2005
• Status: Active Grant

• Current Assignee: Torsten Scheuermann
• Original Assignee: Torsten Scheuermann
• Inventors: Scheuermann, Torsten
• Granted Patent: US 8,046,048 B2
• Time in Patent Office: Days
• US Class Current: 331/177.00V
• CPC Class Codes: G01R 33/286 involving passive visualization of interventional instruments, i.e. making the instrument visible as part of the normal MR process
• CPC Class Codes: G01R 33/3628 Tuning/matching of the transmit/receive coil

Abstract

Systems and methods for a resonator with an adjustable capacitance for a medical device. In one embodiment, a resonator system includes a resonator device with an LC resonator circuit that has an adjustable capacitance, an inductor coil in series with the adjustable capacitance, and an adjustable capacitance control that can control the adjustable capacitance to obtain different particular capacitance values. This embodiment also includes a medical device, positioned with the resonator device, so that at least a portion of the inductor coil surrounds a space that is surrounded by at least a portion of the medical device.

Claims

1. A resonator system, comprising:

a resonator device with an LC resonator circuit, including;

an adjustable capacitance;

an inductor coil in series with the adjustable capacitance; and

a processor coupled to the adjustable capacitance, wherein;

the processor can determine a resonant capacitance; and

the processor can adjust the adjustable capacitance to the resonant capacitance subsequent to determining the resonant capacitance; and

a device deliverable into a body, wherein at least a portion of the device forms at least a portion of the inductor coil.

2. The resonator system of claim 1, wherein:

the resonator device includes a sensor that can transmit one or more signals to the processor; and

the processor can determine the resonant capacitance based at least in part on the one or more signals.

3. The resonator system of claim 2, wherein:

the sensor is a magnetic flux sensor; and

the one or more signals represent one or more sensed fluxes of one or more magnetic fields.

4. The resonator system of claim 2, wherein:

the sensor is a current sensor; and

the one or more signals represent one or more sensed electrical currents through a path of the LC resonator circuit.

5. The resonator system of claim 2, wherein:

the sensor is a voltage sensor; and

the one or more signals represent one or more electrical voltage differentials across the adjustable capacitance.

6. The resonator system of claim 2, wherein the resonator device includes a memory coupled to the processor, wherein the memory can store one or more values that represent the one or more signals transmitted to the processor.

7. The resonator system of claim 2, wherein the resonator device includes a selector coupled to the processor, wherein the selector can be set to one or more settings that represent one or more user inputs.

8. A resonator system, comprising:

a resonator circuit that includes an inductor coil in series with an adjustable capacitance;

a processor coupled to the resonator circuit;

a magnetic flux sensor coupled to the processor, wherein;

the magnetic flux sensor can sense a flux from a magnetic field;

the magnetic flux sensor can transmit a signal based on the sensed flux to the processor;

the processor can determine a resonant capacitance based at least in part on the signal; and

the processor can adjust the adjustable capacitance to the resonant capacitance subsequent to determining the resonant capacitance; and

an implantable medical device, wherein at least a portion of the inductor coil surrounds a space that is surrounded by at least a portion of the implantable medical device.

9. The resonator system of claim 8, wherein the adjustable capacitance includes a plurality of individually switched parallel capacitors.

10. The resonator system of claim 9, wherein the plurality of individually switched parallel capacitors are of increasing size.

11. The resonator system of claim 8, wherein the adjustable capacitance includes a varactor.

12. The resonator system of claim 11, wherein the varactor includes a range of capacitances that is similar to a lower end of a range of estimated adjustable capacitance.

13. The resonator system of claim 8, wherein the adjustable capacitance includes a range of capacitances, wherein the range of capacitances is based on a potential range of MRI Larmor frequencies and an estimated range of inductor coil inductances.

14. The resonator system of claim 8, wherein the implantable medical device is a stent.

15. The resonator system of claim 8, wherein the implantable medical device is a temporarily implantable medical device.

16. A method, comprising:

providing a resonator circuit with an inductor coil in series with an adjustable capacitance to a deliverable device, deliverable in a lumen of a body, so that at least a portion of the inductor coil surrounds at least a portion of the deliverable device;

determining a resonant capacitance at which the resonator circuit will resonate in a particular magnetic field; and

adjusting the adjustable capacitance to the resonant capacitance in the lumen subsequent to determining the resonant capacitance.

17. The method of claim 16, wherein determining the resonant capacitance includes calculating the resonant capacitance of the resonator circuit based on a known flux of the particular magnetic field and a known inductance of the resonator circuit.

18. The method of claim 16, wherein determining the resonant capacitance includes:

adjusting the adjustable capacitance to a known capacitance;

calculating an inductance of the resonator circuit based on the known capacitance and a known flux of the particular magnetic field; and

calculating the resonant capacitance of the resonator circuit based on the known flux and the calculated inductance.

19. The method of claim 16, wherein determining the resonant capacitance includes sensing a frequency response of the resonator circuit.

20. The method of claim 16, wherein adjusting the adjustable capacitance to the resonant capacitance includes changing a number of a plurality of individually switched parallel capacitors

21. The method of claim 16, wherein adjusting the adjustable capacitance to the resonant capacitance includes adjusting a capacitance of a varactor.

22. A method, comprising:

fabricating a resonator device that includes;

a resonator circuit with an inductor coil in series with an adjustable capacitance; and

a processor that can determine a resonant capacitance based at least in part on a flux of a magnetic field and adjust the adjustable capacitance to the resonant capacitance subsequent to determining the resonant capacitance; and

connecting the resonator device to a medical device.

23. The method of claim 22, wherein connecting the resonator device includes connecting the resonator device so that the inductor coil surrounds the medical device and extends beyond both ends of the medical device.

24. The method of claim 22, wherein connecting the resonator device includes implanting the resonator device adjacent to a stent that has already been implanted in a body.

25. The method of claim 22, including implanting the resonator device and the medical device in a body simultaneously.