Implantable marker with a leadless signal transmitter compatible for use in magnetic resonance devices
First Claim
1. A leadless marker for localizing the position of a target within a patient, comprising:
- a casing configured to be positioned at a selected location relative to a target site in the patient;
a resonating circuit without external electrical lead lines extending through the casing, the resonating circuit having an inductor within the casing comprising a plurality of windings of a conductor; and
a ferromagnetic element at least partially within the inductor, the ferromagnetic element having a volume such that when the marker is in an imaging magnetic field having a field strength of 1.5 T and a gradient of 3 T/m, then force exerted on the marker by the imaging magnetic field is not greater than gravitational force exerted on the marker.
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0 Petitions
Accused Products
Abstract
A leadless marker for localizing the position of a target within a patient. In one embodiment, the marker includes a casing, a resonating circuit, and a ferromagnetic element. The casing is configured to be positioned at a selected location relative to a target site in the patient; the casing, for example, can be configured to be permanently or semi-permanently implanted into the patient. The resonating circuit has an inductor within the casing comprising a plurality of windings of a conductor, but it does not have external electrical lead lines extending through the casing. The ferromagnetic element is at least partially within the inductor. The ferromagnetic element has a volume such that when the marker is in an imaging magnetic field having a field strength of 1.5 T and a gradient of 3 T/m, then the force exerted on the marker by the imaging magnetic field is not greater than gravitational force exerted on the marker.
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Citations
54 Claims
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1. A leadless marker for localizing the position of a target within a patient, comprising:
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a casing configured to be positioned at a selected location relative to a target site in the patient;
a resonating circuit without external electrical lead lines extending through the casing, the resonating circuit having an inductor within the casing comprising a plurality of windings of a conductor; and
a ferromagnetic element at least partially within the inductor, the ferromagnetic element having a volume such that when the marker is in an imaging magnetic field having a field strength of 1.5 T and a gradient of 3 T/m, then force exerted on the marker by the imaging magnetic field is not greater than gravitational force exerted on the marker. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 53)
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10. A leadless implantable marker for localizing the position of a target within a patient, comprising:
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a casing configured to be permanently implanted in the patient;
a ferromagnetic element in the casing, the ferromagnetic element having a volume such that when the marker is in an imaging magnetic field having a field strength of 1.5 T and a gradient of 3 T/m, then force exerted on the marker by the magnetic field is not greater than gravitational force exerted on the marker; and
a resonating circuit without external electrical lead lines extending through the casing, the resonating circuit having an inductor within the casing comprising a plurality of windings of a conductor around at least a portion of the ferromagnetic element, wherein the resonating circuit is configured to be energized by an excitation magnetic field and produce a response signal for identifying the position of the marker relative to a reference sensor assembly. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. A wireless implantable marker for localizing the position of a target within a patient, comprising:
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a ferromagnetic core having a length and a cross-sectional dimension normal to the length, wherein the cross-sectional dimension is not greater than 0.7 mm;
a resonating circuit comprising a conductive element having a plurality of windings surrounding at least a portion of the ferromagnetic core, wherein the resonating circuit is not coupled to external electrical leads; and
a casing around the ferromagnetic core and the resonating circuit. - View Dependent Claims (18, 19, 20)
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21. A wireless implantable marker for localizing the position of a target within a patient, comprising:
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a ferromagnetic core having an outer diameter not greater than approximately 0.7 mm;
a coil having windings positioned around at least a portion of the core; and
a casing around the core and the coil without external electrical leads projecting from the casing. - View Dependent Claims (22, 23, 24, 25)
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26. A leadless implantable marker for localizing the position of a target within a patient, comprising:
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a ferromagnetic core having a volume that produces an image artifact not greater than 1500 mm2 in an image from a magnetic resonance device using a magnetic field strength of 1.5 T and a gradient of 3 T/m;
a resonating circuit comprising a conductive element having a plurality of windings surrounding at least a portion of the ferromagnetic core, wherein the resonating circuit is not coupled to external electrical leads; and
a casing enclosing the core and the resonating circuit. - View Dependent Claims (27, 28, 29, 30, 31, 32)
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33. A leadless implantable marker for localizing the position of a target within a patient, comprising:
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a ferromagnetic element having a first end and a second end;
a resonating circuit comprising an inductor having a plurality of windings of a conductor surrounding at least a portion of the ferromagnetic element and a capacitor at the first end of the ferromagnetic element;
a module at the second end of the ferromagnetic element, the module being symmetrical relative to the capacitor; and
a casing around the ferromagnetic element, the resonating circuit and the module. - View Dependent Claims (34, 35, 36, 37, 38, 39, 40)
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41. A method for imaging a target within a patient that has a marker implanted relative to the target, comprising:
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subjecting the patient to a magnetic field in a magnetic resonance imaging device; and
providing a ferrite core in the marker having a volume such that force exerted on the marker by the magnetic field is less than gravitational force exerted on the marker. - View Dependent Claims (42, 43, 44)
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45. A method of manufacturing a marker, comprising:
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providing a ferromagnetic element;
positioning a coil of an inductor at least around a portion of the ferromagnetic element, wherein the coil comprises a plurality of windings of a conductor; and
encasing the ferromagnetic element and the coil in a casing, wherein the ferromagnetic element has a volume such that when the marker is in a magnetic resonance device having a field strength of 1.5 T and a gradient of 3 T/m, then force exerted on the marker by the magnetic field is less than gravitational force exerted on the marker. - View Dependent Claims (46, 47, 48, 49, 50, 51, 52)
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54. A method of manufacturing a marker comprising:
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providing a ferromagnetic element;
positioning a coil of an inductor at least around a portion of the ferromagnetic element, wherein the coil comprises a plurality of windings of a conductor; and
positioning the ferromagnetic element such that the-radiographic and magnetic centroids of the marker are at least substantially coincident.
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Specification