Resonator with adjustable capacitor for medical device

• US 7,838,806 B2
• Filed: 11/02/2007
• Issued: 11/23/2010
• Est. Priority Date: 08/23/2005
• Status: Expired due to Fees

• Current Assignee: Boston Scientific Scimed (Boston Scientific Corporation)
• Original Assignee: Boston Scientific Scimed (Boston Scientific Corporation)
• Inventors: Weber, Jan
• Primary Examiner(s): Van; Quang T
• Application Number:
  US11/982,548
• Publication Number:
  US 20080061788A1
• Time in Patent Office: 1,117 Days
• Field of Search: 219/674, 219660-666, 219778-780, 600/410, 600/411, 600/413, 600421-424, 600/428, 324/322, 324/307, 324/309, 324/318, 607/2, 607/4, 607/9, 607/57, 607/115, 607/116, 607/122
• US Class Current: 219/674
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: A61F 2/82 Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents stent-grafts for tubular structures of the body other than blood vessels A61F2/04; stent-grafts for blood vessels A61F2/07; instruments specially adapted for placement or removal of stents or stent-grafts A61F2/95; for closing wounds, or holding wounds closed A61B17/04 - A61B17/115; dilators A61M29/00
• 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
• CPC Class Codes: Y10T 29/49117 Conductor or circuit manufacturing

Abstract

An apparatus, system and method of a resonator device with an adjustable capacitor for allowing the resonance frequency (F) of the resonator device to continue to be matched to the Larmor frequency of the MRI system. The resonator device includes an inductor coil, a conductive member, a sleeve having first and second sockets that receive at least portions of the inductor coil and the conductive member as electrodes to provide a capacitor structure. Dielectric material can be positioned between at least the first and second sockets, where changes in the cross sectional area defined by the induction coil cause changes in the capacitance value (C) as one or more of the electrodes move within the socket. Changes in the inductance and the capacitance values allow for the resonance frequency (F) of the resonator device to continue to be matched to the Larmor frequency of the MRI system.

Claims

1. A resonator device, comprising:

an inductor coil;

a conductive member that extends from the inductor coil, a portion of the conductive member configured as a spiral extending along a longitudinal axis that defines a passage through which at least a portion of the induction coil passes to form a capacitor structure; and

a sleeve of dielectric material between one of the portion of the conductive member and the portion of the induction coil to form a capacitor structure, where the dielectric layer changes at least one of a thickness and a type along a length of the passage to compensate for changes in a cross-sectional area defined by the inductor coil by changes in a capacitance of the resonator device.

2. The resonator device of claim 1, further including a guide collar that extends from the conductive member forming the spiral, where the portion of the induction coil passes through the guide collar and into the passage.

3. The resonator device of claim 2, where the guide collar extends from a distal end of the conductive member forming the spiral.

4. The resonator device of claim 1, where the conductive member forming the spiral has a non-uniform coil density along a length of the spiral.

5. A resonator device, comprising:

an inductor coil;

a conductive member that extends from the inductor coil, a portion of the conductive member configured as a spiral extending along a longitudinal axis that defines a passage through which at least a portion of the induction coil passes, where the conductive member forming the spiral tapers to allow changes in a distance between the portion of the induction coil that passes into the passage and the conductive member defining the passage; and

a dielectric layer between one of the portion of the conductive member and the portion of the induction coil to form a capacitor structure.

6. A resonator device, comprising:

an inductor coil;

a conductive member that extends from the inductor coil, a portion of the conductive member configured as a spiral extending along a longitudinal axis that defines a passage through which at least a portion of the induction coil passes; and

a dielectric layer between one of the portion of the conductive member and the portion of the induction coil to form a capacitor structure, where the resonance device has a resonance frequency (F) that matches a Larmor frequency of an MRI system, where the F is given by the inverse square root of the product inductance (L) times (x) capacitance (C);

F=1/(2·

(π

)·

(L·

C)^0.5).

7. The resonator device of claim 6, where the F of the resonance device matches the Larmor frequency of the MRI system due to predetermined changes in the capacitance (C) value that correspond to and compensate for changes in the inductance (L) value as a cross-sectional area of the induction coil changes.