Resonator with adjustable capacitance for medical device

• US 20070106151A1
• Filed: 11/09/2005
• Published: 05/10/2007
• Est. Priority Date: 11/09/2005
• Status: Active Grant

• Current Assignee: Boston Scientific Scimed (Boston Scientific Corporation)
• Original Assignee: Boston Scientific Scimed (Boston Scientific Corporation)
• Inventors: Scheuermann, Torsten
• Granted Patent: US 7,423,496 B2
• Time in Patent Office: Days
• US Class Current: 600/424
• 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 for detecting a deliverable device in a body, comprising:

a resonator device with an LC resonator circuit, including;

an adjustable capacitance; and

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; and

a deliverable 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 deliverable device.

2. The resonator system of claim 1, wherein:

the deliverable device is an implantable medical device; and

the resonator device includes a power source that can generate electrical power from a field for use by the adjustable capacitance control, wherein the field is selected from the group including;

an electromagnetic field; and

an alternating magnetic field.

3. The resonator system of claim 2, wherein the adjustable capacitance includes capacitors and a varactor in parallel.

4. The resonator system of claim 2, wherein the resonator device includes a current sensor that can sense an electrical current flow through a path of the LC resonator circuit.

5. The resonator system of claim 2, wherein the resonator device includes a voltage sensor that can sense an electrical voltage differential across the adjustable capacitance.

6. The resonator system of claim 2, wherein:

at least a portion of the inductor coil has an adjustable radius; and

at least a portion of the inductor coil surrounds at least a portion of a passageway of the implantable medical device.

7. The resonator system of claim 6, wherein the implantable medical device is a permanently implantable medical device selected from the group including:

a balloon expandable stent;

a self-expandable stent;

a graft;

a shunt; and

a vena cava filter.

8. The resonator system of claim 6, wherein the implantable medical device is a temporarily implantable medical device selected from the group including:

a guiding catheter;

a guiding wire;

a catheter for stent delivery; and

a catheter for dilation without a stent.

9. The resonator system of claim 1, wherein:

the implantable medical device is a temporarily implantable medical device; and

the resonator device is inside the temporarily implantable medical device.

10. A resonator system, comprising:

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

an adjustable capacitance control that can automatically adjust the adjustable capacitance to a resonant capacitance in response to magnetic fields of different strength;

a power source connected to the adjustable capacitance; and

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

11. The resonator system of claim 10, including a selector that manually adjusts the adjustable capacitance, at least in part, by changing a number of the parallel capacitors that are connected to the resonator circuit.

12. The resonator system of claim 10, wherein:

the adjustable capacitance includes capacitors that are;

in parallel; and

connectable to the resonator circuit; and

the adjustable capacitance control automatically adjusts the adjustable capacitance, at least in part, by changing a number of the parallel capacitors that are connected to the resonator circuit.

13. The resonator system of claim 12, wherein:

the adjustable capacitance includes a varactor that is;

parallel to the parallel capacitors; and

connectable to the resonator circuit; and

the adjustable capacitance control automatically adjusts the adjustable capacitance, at least in part, by adjusting a capacitance of the varactor.

14. The resonator system of claim 10, including a sensor:

connected to a processor; and

selected from the group including;

a magnetic flux sensor;

a voltage sensor connected across the adjustable capacitance; and

a current sensor connected in line with a path of the resonator circuit.

15. The resonator system of claim 10, wherein the power source is selected from the group including:

the inductor coil;

a coil;

a battery;

a capacitor; and

a secondary resonator circuit.

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.

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 of the resonator circuit.

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

sensing a flux of the particular magnetic field; and

calculating the resonant capacitance of the resonator circuit, based on the sensed flux and a known inductance of the resonator circuit.

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

sensing a flux of the particular magnetic field;

adjusting the adjustable capacitance to a known capacitance;

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

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

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

adjusting the adjustable capacitance to a particular capacitance;

sensing a voltage across the adjustable capacitance; and

repeating the adjusting and the sensing to determine a particular capacitance at which the voltage across the adjustable capacitance is a maximum voltage that can be obtained by the adjustable capacitance in the particular magnetic field.

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

adjusting the adjustable capacitance to a particular capacitance;

sensing a current through the resonator circuit at the particular capacitance; and

repeating the adjusting and the sensing to determine a particular capacitance at which the current through the resonator circuit is a maximum current that can be obtained by the adjustable capacitance in the particular magnetic field.

23. A method, comprising:

fabricating a resonator device that includes;

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

an adjustable capacitance control that can automatically adjust the adjustable capacitance to a resonant capacitance in response to magnetic fields of different strength; and

connecting the resonator device to a medical device so that at least a portion of the inductor coil surrounds at least a portion of the medical device.

24. The method of claim 23 wherein:

fabricating the resonator device includes fabricating an inductor coil out of a flexible conductive material so that the coil has an adjustable radius; and

connecting the resonator includes securing the inductor coil around a stent so that the adjustable radius can increase as the stent expands.

25. The method of claim 23, wherein connecting the resonator includes securing the resonator device in a distal end of a catheter.