WO2007140389A2

WO2007140389A2 - Magnetic resonance imaging stent having inter-luminal compatibility with magnetic resonance imaging

Info

Publication number: WO2007140389A2
Application number: PCT/US2007/069934
Authority: WO
Inventors: Andreas Melzer; Robert W. Gray; Michael L. Weiner; Stuart G. Macdonald
Original assignee: Biophan Technologies, Inc.; Amris Gmbh
Priority date: 2006-05-30
Filing date: 2007-05-30
Publication date: 2007-12-06
Also published as: WO2007140389A3

Abstract

A stent includes a subset of struts having a notched formed therein and a conductor having a first end and a second end. The conductor is connected to the subset of struts at the notches to provide a mechanical connection between the conductor and the subset of struts. The conductor is electrical insulated from the subset of struts by an insulative material in the notches. The conductor is formed on a portion of struts within the subset of struts to form an electrical loop with an insulative material between the conductor and the struts. The first end of the conductor overlaps the second end of the conductor, the overlapping of the first end of the conductor and the second end of the conductor being located on a strut within the subset of struts. The first end of the conductor and the second end of the conductor have a dielectric material therebetween to form a capacitor.

Description

MAGNETIC RESONANCE IMAGING STENT HAVING INTER-LUMINAL COMPATIBILITY WITH MAGNETIC RESONANCE IMAGING

TECHNICAL FIELD

[0001] The present invention is directed to a stent. More particularly, the present invention is directed to a stent that can be interiorly imaged, non-invasively, using magnetic resonance imaging.

BACKGROUND ART

[0002] Stents have been implanted in vessels, ducts, or channels of the human body to act as a scaffolding to maintain the patency of the vessel, duct, or channel lumen. A drawback of stenting is the body's natural defensive reaction to the implant of a foreign object. In many patients, the reaction is characterized by a traumatic proliferation of tissue as intimal hyperplasia at the implant site, and, where the stent is implanted in a blood vessel such as a coronary artery, formation of thrombi which become attached to the stent.

[0003] Each of these adverse effects contributes to restenosis~a re-narrowing of the vessel lumen-to compromise the improvements that resulted from the initial re-opening of the lumen by implanting the stent. Consequently, a great number of stent implant patients must undergo another angiogram, on average about six months after the original implant procedure, to determine the status of tissue proliferation and thrombosis in the affected lumen. If re-narrowing has occurred, one or more additional procedures are required to stem or reverse its advancement.

[0004] Due to the drawbacks mentioned above, the patency of the vessel lumen and the extent of tissue growth within the lumen of the stent need to be examined and analyzed, and the blood flow therethrough needs to be measured, from time to time, as part of the patient's routine post-procedure examinations.

[0005] Current techniques employed magnetic resonance imaging to visualize internal features of the body if there is no magnetic resonance distortion. However, using magnetic resonance imaging techniques to visualize implanted stents composed of ferromagnetic or electrically conductive materials is difficult because these materials cause sufficient distortion of the magnetic resonance field to preclude imaging the interior of the stent. This effect is attributable to their Faradaic physical properties in relation to the electromagnetic energy applied during the magnetic resonance imaging process. [0006] One conventional solution to this problem is to design a stent that includes a mechanically supportive tubular structure composed primarily of metal having relatively low magnetic susceptibility, and one electrically conductive layer overlying a portion of the surface of the tubular structure to enhance properties of the stent for magnetic resonance imaging of the interior of the lumen of the stent when implanted in the body. An electrically insulative layer resides between the surface of the tubular structure of the stent and the electrically conductive layer. The tubular structure with overlying electrically conductive layer and electrically insulative layer sandwiched therebetween are arranged in a composite relationship to form an LC circuit at the desired frequency of magnetic resonance. The electrically conductive layer has a geometric formation arranged on the tubular scaffolding of the stent to function as an electrical inductance element and an electrical capacitance element.

[0007] Although the proposed solution may provide a stent structure that enables imaging and visualization of the inner lumen of an implanted stent by means of a magnetic resonance imaging technique, the actual structure of the stent that provides the imaging and visualization of the inner lumen of an implanted stent is dependent upon the actual structure of the stent. Thus, the stent must be designed in a particular manner to interactive with the overlying layer to provide a stent structure that enables imaging and visualization of the inner lumen of an implanted stent. [0008] Inter-luminal stents are commonly fabricated by selectively removing materials from metallic tubes to form complex geometrical structures that enable the stent to be alternately reduced in diameter for delivery and subsequently expanded to provide therapeutic benefit. Unfortunately, the geometry of the stent, combined with the high electrical conductivity of the metallic materials from which the stents are produced, serve to create an effective shield against electromagnetic radiation. This shielding effect prevents the interior of the stent to be imaged, non-invasively, using magnetic resonance imaging.

[0009] It has been shown that disruption of the electrically conductive pathways formed by the stents geometrical structure, i.e. the "struts" of the stent, can reduce or eliminate the shielding effect, as illustrated in Figures 33-36. However, creating the desired disruption without compromising the mechanical properties of the stent has proven to be difficult to achieve in practice. [0010] Therefore, it is desirable to provide a device which enables imaging and visualization of the inner lumen of an implanted stent by means of a magnetic resonance imaging technique and which is independent of the stent structure. [0011] It is also desirable to provide a device that enables the effective designing of a stent to provide scaffolding so as to maintain the patency of the vessel, duct or channel lumen without having to design features into the stent to enable imaging and visualization of the inner lumen of an implanted stent by means of an magnetic resonance imaging technique.

[0012] Furthermore, it is desirable to provide a device that consists of a composite metallic tube that has incorporated into it one or more sections that create a very high level of resistance to the flow of electrical current. The stents are then fabricated from this composite metallic tube in such a way that one or more of the stent struts has, within it, a region of high electrical resistance.

DISCLOSURE OF THE INVENTION

[0013] One aspect of the present invention is a stent sleeve. The stent sleeve includes an insulative substrate and a conductive trace with a first end and a second end. The conductive trace forms an inductive coil. The first end of the conductive trace overlapping the second end of the conductive trace with a dielectric material between the first end of the conductive trace and the second end of the conductive trace to form a capacitor.

[0014] Another aspect of the present invention is a stent. The stent includes a plurality of struts; a plurality of strut connectors to provide a mechanical connection between adjacent struts; and a conductor having a first end and a second end. The conductor is formed on a set of the plurality of strut connectors and a set of struts to form an electrical loop with a dielectric material between the conductor and the struts and between the conductor and the set of the plurality of strut connectors. The first end of the conductor overlaps the second end of the conductor, the overlapping of the first end of the conductor and the second end of the conductor being located on a strut. The first end of the conductor and the second end of the conductor have a dielectric material therebetween to form a capacitor.

[0015] Another aspect of the present invention is a stent. The stent includes a plurality of struts; a plurality of strut connectors to provide a mechanical connection between adjacent struts; and a conductor having a first end and a second end. The conductor is formed on a set of the plurality of strut connectors and a set of struts to form an electrical loop with an insulative material between the conductor and the struts and between the conductor and the set of the plurality of strut connectors. The first end of the conductor overlaps the second end of the conductor, the overlapping of the first end of the conductor and the second end of the conductor being located on a strut. The first end of the conductor and the second end of the conductor have a dielectric material therebetween to form a capacitor.

[0016] Another aspect of the present invention is a stent. The stent includes a plurality of struts, a subset of the plurality of struts having a notched formed therein, and a conductor having a first end and a second end. The conductor is connected to the subset of the plurality of struts at the notches to provide a mechanical connection between the conductor and the subset of the plurality of struts. The conductor is electrical insulated from the subset of the plurality of struts by an insulative material in the notches. The conductor is formed on a portion of struts within the subset of the plurality of struts to form an electrical loop with an insulative material between the conductor and the struts. The first end of the conductor overlaps the second end of the conductor, the overlapping of the first end of the conductor and the second end of the conductor being located on a strut within the subset of the plurality of struts. The first end of the conductor and the second end of the conductor have a dielectric material therebetween to form a capacitor.

[0017] Another aspect of the present invention is a stent. The stent includes a plurality of struts, each strut having a first end and a second end, and an H-shaped connector having a first channel and a second channel, the first channel having an insulative material therein, the second channel having an insulative material therein. The first end of a strut is connected to the first channel. The second end of a strut is connected to the second channel.

[0018] Another aspect of the present invention is a stent. The stent includes a plurality of struts, each ring having a first end and a second end, and an H-shaped connector having a first channel and a second channel, the first channel having an insulative material therein, the second channel having an insulative material therein. The first end of each strut is connected to the first channel. The second end of each strut is connected to the second channel.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention may take form in various components and arrangements of components, and in various steps and arrangements of steps. The drawings are only for purposes of illustrating a preferred embodiment or embodiments and are not to be construed as limiting the present invention, wherein:

[0020] Figure 1 shows a sleeve substrate having a resonance coil formed thereon according to the concepts of the present invention;

[0021] Figure 2 shows the wrapping of the sleeve substrate of Figure 1 according to the concepts of the present invention;

[0022] Figure 3 shows the crimped sleeve substrate wrapped around a collapsed stent according to the concepts of the present invention;

[0023] Figure 4 illustrates a manufacturing web transporting a number of sleeve substrates according to the concepts of the present invention;

[0024] Figure 5 a sleeve substrate having a resonance coil formed using a folding routine according to the concepts of the present invention;

[0025] Figure 6 shows the sleeve substrate of Figure 5 prior to folding according to the concepts of the present invention;

[0026] Figure 7 shows a manufacturing device for forming the resonance coil upon a substrate;

[0027] Figure 8 shows another embodiment of a sleeve substrate having a resonance coil and variable capacitance formed thereon according to the concepts of the present invention;

[0028] Figure 9 shows the wrapping of the sleeve substrate of Figure 8 according to the concepts of the present invention;

[0029] Figure 10 shows another embodiment of a sleeve substrate having a resonance coil and variable capacitance formed thereon according to the concepts of the present invention;

[0030] Figure 11 shows the wrapping of the sleeve substrate of Figure 10 according to the concepts of the present invention;

[0031] Figure 12 shows another embodiment of a sleeve substrate having a resonance coil formed thereon according to the concepts of the present invention;

[0032] Figure 13 shows another embodiment of a sleeve substrate having a resonance coil and non-linear variable capacitance formed thereon according to the concepts of the present invention;

[0033] Figure 14 shows a sleeve substrate formed around a stent according to the concepts of the present invention; [0034] Figure 15 shows another embodiment of a sleeve substrate having a resonance coil and non-linear variable capacitance formed thereon according to the concepts of the present invention;

[0035] Figure 16 is an expanded view of the traces showing the resonance coil construction;

[0036] Figure 17 shows a sleeve substrate having multiple resonance coils formed thereon according to the concepts of the present invention;

[0037] Figure 18 shows another embodiment of a sleeve substrate having multiple resonance coils and variable capacitance formed thereon according to the concepts of the present invention;

[0038] Figure 19 shows the wrapping of the sleeve substrate of Figure 18 according to the concepts of the present invention;

[0039] Figure 20 shows a sleeve substrate having a resonance coil with multiple (stacked) loops formed thereon according to the concepts of the present invention; [0040] Figure 21 shows a side perspective of the sleeve substrate having a resonance coil with multiple (stacked) loops formed thereon illustrated by Figure 20 according to the concepts of the present invention;

[0041] Figure 22 illustrates a stent assembly according to the concepts of the present invention;

[0042] Figure 23 illustrates resonant circuits on a cylinder membrane according to the concepts of the present invention;

[0043] Figure 24 illustrates a stent sleeve assembly according to the concepts of the present invention;

[0044] Figure 25 illustrates circuits on a flat film membrane wrapped around a stent according to the concepts of the present invention;

[0045] Figure 26 illustrates forming circuits on a membrane according to the concepts of the present invention;

[0046] Figure 27 illustrates a side view of the stent circuit assembly according to the concepts of the present invention;

[0047] Figure 28 illustrates a substrate having a resonance coil with multiple (non- stacked) loops formed thereon according to the concepts of the present invention; [0048] Figures 29 illustrate examples of disrupting the electrically conductive pathways formed by the geometrical structure of the stent to reduce or eliminate the shielding effect; [0049] Figures 30-33 illustrate prior art examples of disrupting the electrically conductive pathways formed by the geometrical structure of the stent to reduce or eliminate the shielding effect;

[0050] Figures 34-37 illustrate further examples of sleeves for a stent to enable the stent to be interiorly imaged, non-invasively, using magnetic resonance imaging;

[0051] Figure 38 illustrates models of stents according to the concepts of the present invention;

[0052] Figure 39 shows a graph of the relative capacitance versus field amplitude for various embodiments of stents with a resonant circuit thereon;

[0053] Figure 38 illustrates magnetic field intensity around current carrying conductor;

[0054] Figures 39-41 illustrate embodiments of stents capable of being interiorly imaged, non-invasively, using magnetic resonance imaging;

[0055] Figures 42-43 illustrate a mechanical bonding of stent's struts having a disruption of the electrically conductive pathways formed by the stents geometrical structure;

[0056] Figures 44-46 illustrate stent structures;

[0057] Figure 47 illustrates a stent assembly according to the concepts of the present invention;

[0058] Figure 48 illustrates another stent assembly according to the concepts of the present invention;

[0059] Figure 49 illustrates another stent assembly according to the concepts of the present invention;

[0060] Figures 50 illustrates a portion of a stent assembly according to the concepts of the present invention;

[0061] Figures 51 illustrates a portion of a stent assembly according to the concepts of the present invention;

[0062] Figures 52 illustrates a portion of a stent assembly according to the concepts of the present invention;

[0063] Figures 53 illustrates a portion of a stent assembly according to the concepts of the present invention;

[0064] Figures 54 illustrates a portion of a stent assembly according to the concepts of the present invention; [0065] Figures 55 illustrates a portion of a stent assembly according to the concepts of the present invention;

[0066] Figures 56 illustrates a portion of a stent assembly according to the concepts of the present invention;

[0067] Figure 57 illustrates another stent assembly according to the concepts of the present invention;

[0068] Figure 58 illustrates another stent assembly according to the concepts of the present invention;

[0069] Figure 59 illustrates another stent assembly according to the concepts of the present invention;

[0070] Figure 60 illustrates a portion of a stent assembly according to the concepts of the present invention; and

[0071] Figure 61 illustrates a portion of a stent assembly according to the concepts of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

[0072] The present invention will be described in connection with preferred embodiments; however, it will be understood that there is no intent to limit the present invention to the embodiments described herein. On the contrary, the intent is to cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the present invention as defined by the appended claims. [0073] For a general understanding of the present invention, reference is made to the drawings. It is noted that the various drawings illustrating the present invention may not have been drawn to scale and that certain regions may have been purposely drawn disproportionately so that the features and concepts of the present invention could be properly illustrated.

[0074] As noted above, the present invention is directed to a device which enables imaging and visualization of the inner lumen of an implanted stent by means of an magnetic resonance imaging technique and which is independent of the stent structure and/or a device that enables the effective designing of a stent to provide scaffolding so as to maintain the patency of the vessel, duct or channel lumen without having to design features into the stent to enable imaging and visualization of the inner lumen of an implanted stent by means of an magnetic resonance imaging technique. [0075] As illustrated in Figure 1 , a substrate 100 has formed thereon conductive traces 130, composed of film coatings of metal or any thin pliable conductive material. The traces 130 are formed so as to create a resonance coil or coils 120 that will be used in forming a LC circuit that is tuned to the desired frequency of magnetic resonance imaging or other desired frequency. It is noted that the traces 130 may also be formed so as to create a resonance coil or coils 120 that will be used in forming a RLC circuit that is tuned to the desired frequency of magnetic resonance imaging or other desired frequency.

[0076] In this embodiment, the "resistor" is the "conductive" material or conductive traces 130. The resistor value is controlled by the dimensions of the conductor as well as the material selected for the conductor. Also, the material for the conductor may vary along the length of the tracing forming the inductor, thereby providing a resistive parameter to the circuit.

[0077] The degree of resonance or 'Q' of either the formed LC or formed RLC circuit is a degree of resonance at the Lamar frequency of the magnetic resonance imaging system or the desired resonance frequency to permit clinically effective imaging inside the lumen of the stent. It is noted that this is the frequency of the system as deployed; e.g. in vitro; not the frequency in air.

[0078] The substrate 100 may, optionally, include a nominal capacitor 110 to provide a minimum capacitance for the LC or RLC circuit that is tuned to desired frequency of magnetic resonance imaging or other desired frequency.

[0079] The substantial portion of the capacitance may be realized by the capacitance between the traces 130 in region 115 when the substrate 100 is wrapped into a substantially cylinder shape, as illustrated in Figure 2, to form a sleeve. The substrate 100 can be wrapped around a medical device as illustrated in Figure 3. When surrounding a medical device, the traces 130 are insulated by an insulative dielectric material (not shown) so that when the traces 130 in region 115 overlap, due to the wrapping of the substrate 100 as illustrated in Figure 2, the overlapped portions of the traces 130 form a capacitor. The capacitance of the trace formed capacitor in region 115 is variable as the wrapping of the substrate 100 becomes tighter (contracts) or is loosened (expands).

[0080] As noted above, the stent must enable imaging and visualization of the inner lumen of an implanted stent by means of a magnetic resonance imaging technique, thus the stent must have an associated resonance circuit that is tuned to the desired frequency of magnetic resonance. The substrate sleeve of Figure 1 provides the resonance circuit that may be tuned to the desired frequency of magnetic resonance or other desired frequency, independent of the stent.

[0081] To be in resonance, the resonance circuit of the substrate sleeve of Figure 1 must include an LC or RLC circuit that is tuned to the desired frequency of magnetic resonance or other desired frequency. In this embodiment, the traces 130 are formed to create the inductive properties and the overlapping of the traces, when the sleeve is wrapped, creates the capacitive properties. Again, it is noted that a resistive value related to the dimensions of the conductor as well as the material selected for the conductor may be included in the resonance circuit of the substrate sleeve.

[0082] It is noted that as the wrapping of the substrate 100 becomes tighter

(contracts), the overall inductance of the resonance circuit of the substrate sleeve decreases, but the overall capacitance of the resonance circuit of the substrate sleeve increases because the area of the overlapping trace portions becomes greater, thereby substantially maintaining resonance with the desired frequency of magnetic resonance imaging or other desired frequency.

[0083] It is noted that the combination of the decreasing of the overall inductance of the resonance circuit of the substrate sleeve and the increasing of the overall capacitance of the resonance circuit of the substrate sleeve may also enable the maintaining of resonance within a desired bandwidth, which may or may not be in resonance with the magnetic resonance imaging scanner.

[0084] It is also noted that as the wrapping of the substrate 100 becomes looser

(expands), the overall inductance of the resonance circuit of the substrate sleeve increases, but the overall capacitance of the resonance circuit of the substrate sleeve decreases because the area of the overlapping trace portions becomes lesser, thereby substantially maintaining resonance with the desired frequency of magnetic resonance imaging or other desired frequency.

[0085] It is noted that the combination of the increasing of the overall inductance of the resonance circuit of the substrate sleeve and the decreasing of the overall capacitance of the resonance circuit of the substrate sleeve may also enable the maintaining of resonance within a desired bandwidth, which may or may not be in resonance with the magnetic resonance imaging scanner.

[0086] The substrate 100 may be a biodegradable substrate that essentially decomposes once the stent is positioned in the body. It is further noted that the substrate 100 may be thermally degradable, chemically degradable, and/or optically degradable. The substrate 100 may also include drugs or medical agents that are therapeutically released upon the decomposition of the substrate. Lastly, the substrate 100 and included resonance circuit are expandable without resulting in breakage. It is noted that the substrate or support web 100, may be biodegradable and may have adhesive properties useful during manufacture and implantation; however, after biodegradation, the applied conductive traces 130 retain an electrically insulating coating or sheath that prevents unwanted shorting even under repeated flexing of the stent/circuit device in the body.

[0087] As discussed above, the substrate sleeve is wrapped, more particularly; the substrate sleeve is wrapped around a stent and crimped, as illustrated in Figure 3, to form a stent device with an independent resonance circuit. The resonance circuit can be designed to complement the resonance frequency of an implanted stent so that the combination of the resonance circuit, the implanted stent, and surrounding environmental conditions has an effective resonance frequency that is substantially equal to the operating frequency of the magnetic resonance imaging scanner. It is noted that the resonance circuit can be designed to complement the resonance frequency of any implanted device having a lumen to be imaged so that the combination of the resonance circuit, the implanted device, and surrounding environmental conditions has an effective resonance frequency that is substantially equal to the operating frequency of the magnetic resonance imaging scanner. Moreover, the resonance circuit need not be designed to interact with the conductive material of the stent to provide resonance, but merely needs to be designed to contemplate the degree of expansion of the stent so that the proper inductance can be generated with the coil formations and the proper capacitance can be generated with the trace overlap. [0088] As illustrated in Figure 17, a substrate 100 has formed thereon conductive traces (2000 2100, 2200, and 2300) composed of film coatings of metal or any thin pliable conductive material. The traces are formed so as to create independent resonance coils tuned to different frequencies. It is noted that these frequencies may be harmonics. The coils are formed by the traces running on top of each other with an insulating material therebetween. It is noted that the insulating material may be a dielectric to provide capacitance.

[0089] The conductive traces (2000 2100, 2200, and 2300) are used in forming a LC circuit that is tuned to the desired frequency of magnetic resonance imaging or other desired frequency. It is noted that the traces may also be formed so as to create independent resonance coils that will be used in forming a RLC circuit that is tuned to the desired frequency of magnetic resonance imaging or other desired frequency. [0090] In this embodiment, the "resistor" is the "conductive" material or conductive traces. The resistor value is controlled by the dimensions of the conductor as well as the material selected for the conductor. Also, the material for the conductor may vary along the length of the tracing forming the inductor, thereby providing a resistive parameter to the circuit.

[0091] The degree of resonance or 'Q' of either the formed LC or formed RLC circuit is a degree of resonance at the Lamar frequency of the magnetic resonance imaging system to permit clinically effective imaging inside the lumen of the stent. [0092] As illustrated in Figure 8, a substrate 100 has formed thereon a conductive trace 1300, composed of film coating of metal or any thin pliable conductive material. The trace 1300 is formed so as to create a single resonance coil that will be used in forming a LC circuit that is tuned to the desired frequency of magnetic resonance imaging or other desired frequency. It is noted that the trace 1300 can be formed so as to create a single resonance coil of a multi-loop inductor coil, as illustrated in Figure 28, wherein the multi-loop inductor coil will be used in forming a LC circuit that is tuned to the desired frequency of magnetic resonance imaging or other desired frequency It is further noted that the traces 1300 may also be formed so as to create a resonance coil that will be used in forming a RLC circuit that is tuned to the desired frequency of magnetic resonance imaging or other desired frequency. Also, it is noted that the traces 1300 may also be formed so as to create a single resonance coil of a multi-loop inductor coil, as illustrated in Figure 28, wherein the multi-loop inductor coil will be used in forming a RLC circuit that is tuned to the desired frequency of magnetic resonance imaging or other desired frequency.

[0093] In this embodiment, the "resistor" is the "conductive" material or conductive traces 1300. The resistor value is controlled by the dimensions of the conductor as well as the material selected for the conductor. Also, the material for the conductor may vary along the length of the tracing forming the inductor, thereby providing a resistive parameter to the circuit.

[0094] The degree of resonance or 'Q' of either the formed LC or formed RLC circuit is a degree of resonance at the Lamar frequency of the magnetic resonance imaging system to permit clinically effective imaging inside the lumen of the stent. [0095] The capacitance is realized by the capacitance by the overlapping of the end portions of the trace 1300 in region 1350 when the substrate 100 is wrapped into a substantially cylinder shape, as illustrated in Figure 9, to form a sleeve. The trace 1300 is insulated by an insulative dielectric material (not shown) so that when the end portions of the trace 1300 in region 1350 overlap, due to the wrapping of the substrate 100 as illustrated in Figure 9, the overlapped portions of the trace 1300 form a capacitor. The capacitance of the trace formed capacitor in region 1350 is variable as the wrapping of the substrate 100 becomes tighter (contracts) or is loosened (expands). [0096] As noted above, the stent must enable imaging and visualization of the inner lumen of an implanted stent by means of a magnetic resonance imaging technique, thus the stent must have an associated resonance circuit that is tuned to the desired frequency of magnetic resonance when deployed in the patient's body or deployed in vitro. The substrate sleeve of Figures 8 and 9 provides the resonance circuit that is tuned to the desired frequency of magnetic resonance independent of the stent. The resonance circuit of Figures 8 and 9 can also be designed to complement the resonance frequency of an implanted stent so that the combination of the resonance circuit, the implanted stent, and surrounding environmental conditions has an effective resonance frequency that is substantially equal to the operating frequency of the magnetic resonance imaging scanner. It is noted that the resonance circuit can be designed to complement the resonance frequency of any implanted device having a lumen to be imaged so that the combination of the resonance circuit, the implanted device, and surrounding environmental conditions has an effective resonance frequency that is substantially equal to the operating frequency of the magnetic resonance imaging scanner.

[0097] To be in resonance, the substrate sleeve of Figures 8 and 9 must include an LC or RLC circuit such that the entire implanted system is tuned to the desired frequency of magnetic resonance when deployed in a patient's body or other desired frequency.

[0098] In this embodiment, the traces 1300 are formed to create the inductive properties and the overlapping of the traces, when the sleeve is wrapped, creates the capacitive properties. Again, it is noted that a resistive value related to the dimensions of the conductor as well as the material selected for the conductor may be included in the resonance circuit of the substrate sleeve. [0099] It is noted that as the wrapping of the substrate 100 becomes tighter (contracts), the overall inductance of the resonance circuit of the substrate sleeve decreases, but the overall capacitance of the resonance circuit of the substrate sleeve increases because the area of the overlapping trace portions becomes greater, thereby substantially maintaining resonance with the desired frequency of magnetic resonance imaging or other desired frequency.

[0100] It is noted that the combination of the decreasing of the overall inductance of the resonance circuit of the substrate sleeve and the increasing of the overall capacitance of the resonance circuit of the substrate sleeve may also enable the maintaining of resonance within a desired bandwidth, which may or may not be in resonance with the magnetic resonance imaging scanner.

[0101] It is also noted that as the wrapping of the substrate 100 becomes looser (expands), the overall inductance of the substrate sleeve increases, but the overall capacitance of the substrate sleeve decreases because the area of the overlapping trace portions becomes lesser, thereby substantially maintaining resonance with the desired frequency of magnetic resonance imaging or other desired frequency. [0102] It is noted that the combination of the increasing of the overall inductance of the resonance circuit of the substrate sleeve and the decreasing of the overall capacitance of the resonance circuit of the substrate sleeve may also enable the maintaining of resonance within a desired bandwidth, which may or may not be in resonance with the magnetic resonance imaging scanner.

[0103] The substrate 100 may be a biodegradable substrate that essentially decomposes once the stent is positioned in the body. It is further noted that the substrate 100 may be thermally degradable, chemically degradable, and/or optically degradable. The substrate 100 may also include drugs or medical agents that are therapeutically released upon the decomposition of the substrate. Lastly, the substrate 100 and included resonance circuit are expandable without resulting in breakage. It is noted that the substrate or support web 100, may be biodegradable and may have adhesive properties useful during manufacture and implantation; however, after biodegradation, the applied conductive traces 1300 retain an electrically insulating coating or sheath that prevents unwanted shorting even under repeated flexing of the stent/circuit device in the body.

[0104] The embodiment illustrated in Figure 8 is applicable to a resonance coil constructed of multiple or stacked loops, as illustrated in Figure 20. In Figure 20, a substrate 100 has formed thereon a conductive trace with stacked or multiple loops (4000, 4100, 4200, and 4300), composed of film coating of metal or any thin pliable conductive material. The trace is formed so as to create a single resonance coil having stacked or multiple loops (4000, 4100, 4200, and 4300) that will be used in forming a LC circuit that is tuned to the desired frequency of magnetic resonance imaging or other desired frequency. It is noted that the trace may also be formed so as to create a resonance coil that will be used in forming a RLC circuit that is tuned to the desired frequency of magnetic resonance imaging or other desired frequency. [0105] In this embodiment, the "resistor" is the "conductive" material or conductive trace. The resistor value is controlled by the dimensions of the conductor as well as the material selected for the conductor. Also, the material for the conductor may vary along the length of the tracing forming the inductor, thereby providing a resistive parameter to the circuit.

[0106] The degree of resonance or 'Q' of either the formed LC or formed RLC circuit is a degree of resonance at the Lamar frequency of the magnetic resonance imaging system to permit clinically effective imaging inside the lumen of the stent. [0107] The capacitance is realized by the capacitance by the overlapping of the end portions of the trace when the substrate 100 is wrapped into a substantially cylinder shape to form a sleeve. The trace is insulated by an insulative dielectric material (not shown) so that when the end portions of the trace overlap, due to the wrapping of the substrate 100, the overlapped portions of the trace form a capacitor. The capacitance of the trace formed capacitor is variable as the wrapping of the substrate 100 becomes tighter (contracts) or is loosened (expands).

[0108] As noted above, the stent must enable imaging and visualization of the inner lumen of an implanted stent by means of a magnetic resonance imaging technique, thus the stent must have an associated resonance circuit that is tuned to the desired frequency of magnetic resonance. The substrate sleeve provides the resonance circuit that is tuned to the desired frequency of magnetic resonance independent of the stent. The resonance circuit can also be designed to complement the resonance frequency of an implanted stent so that the combination of the resonance circuit, the implanted stent, and surrounding environmental conditions has an effective resonance frequency that is substantially equal to the operating frequency of the magnetic resonance imaging scanner. It is noted that the resonance circuit can be designed to complement the resonance frequency of any implanted device having a lumen to be imaged so that the combination of the resonance circuit, the implanted device, and surrounding environmental conditions has an effective resonance frequency that is substantially equal to the operating frequency of the magnetic resonance imaging scanner. [0109] To be in resonance, the substrate sleeve of Figure 20 must include an LC or RLC circuit that is tuned to the operating frequency of the magnetic resonance imaging scanner or other desired frequency.

[0110] In this embodiment, the trace has stacked or multiple loops (4000, 4100, 4200, and 4300) to create the inductive properties and the overlapping of the trace, when the sleeve is wrapped, creates the capacitive properties. Again, it is noted that a resistive value related to the dimensions of the conductor as well as the material selected for the conductor may be included in the resonance circuit of the substrate sleeve.

[0111] It is noted that as the wrapping of the substrate 100 becomes tighter (contracts), the overall inductance of the resonance circuit of the substrate sleeve decreases, but the overall capacitance of the resonance circuit of the substrate sleeve increases because the area of the overlapping trace portions becomes greater, thereby substantially maintaining resonance with the desired frequency of magnetic resonance imaging or other desired frequency.

[0112] It is noted that the combination of the decreasing of the overall inductance of the resonance circuit of the substrate sleeve and the increasing of the overall capacitance of the resonance circuit of the substrate sleeve may also enable the maintaining of resonance within a desired bandwidth, which may or may not be in resonance with the magnetic resonance imaging scanner.

[0113] It is also noted that as the wrapping of the substrate 100 becomes looser (expands), the overall inductance of the substrate sleeve increases, but the overall capacitance of the substrate sleeve decreases because the area of the overlapping trace portions becomes lesser, thereby substantially maintaining resonance with the desired frequency of magnetic resonance imaging or other desired frequency. [0114] It is noted that the combination of the increasing of the overall inductance of the resonance circuit of the substrate sleeve and the decreasing of the overall capacitance of the resonance circuit of the substrate sleeve may also enable the maintaining of resonance within a desired bandwidth, which may or may not be in resonance with the magnetic resonance imaging scanner. [0115] The substrate 100 may be a biodegradable substrate that essentially decomposes once the stent is positioned in the body. It is further noted that the substrate 100 may be thermally degradable, chemically degradable, and/or optically degradable. The substrate 100 may also include drugs or medical agents that are therapeutically released upon the decomposition of the substrate. Lastly, the substrate 100 and included resonance circuit are expandable without resulting in breakage. It is noted that the substrate or support web 100, may be biodegradable and may have adhesive properties useful during manufacture and implantation; however, after biodegradation, the applied conductive traces 1300 retain an electrically insulating coating or sheath that prevents unwanted shorting even under repeated flexing of the stent/circuit device in the body.

[0116] As illustrated in Figure 20, end portions of the multiple or stacked loops (4000, 4100, 4200, and 4300) may be aligned along dotted lines 5000 and 5100. The multiple or stacked loops (4000, 4100, 4200, and 4300) are electrically connected to each other by conductive trace portions (4050, 4150, and 4250). More specifically, loop 4000 may be electrically connected to loop 4100 through conductive trace portion 4050; loop 4100 may be electrically connected to loop 4200 through conductive trace portion 4150; and loop 4200 may be electrically connected to loop 4300 through conductive trace portion 4250. By connecting the various loops in this fashion, an inductive coil is realized. [0117] It is noted that the conductive trace portions may be replaced with a dielectric to provide a capacitive connection between the multiple or stacked loops. A better illustration of this construction is provided by Figure 21 , which illustrates a side perspective of the multiple or stacked loops at cross-section 6000 of Figure 20. [0118] In Figure 21 , the multiple or stacked loops (4000, 4100, 4200, and 4300) are formed on the substrate 100. Between each loop, an insulating film or layer 4025 is provided.

[0119] As illustrated in Figure 21 , loop 4000 is formed on substrate 100 and may be electrically connected to loop 4100 through conductive trace portion 4050 with an insulating film or layer 4025 between loop 4000 and loop 4100; loop 4100 may be electrically connected to loop 4200 through conductive trace portion 4150 with an insulating film or layer 4025 between loop 4100 and loop 4200; and loop 4200 may be electrically connected to loop 4300 through conductive trace portion 4250 with an insulating film or layer 4025 between loop 4200 and loop 4300. Again, by connecting the various loops in this fashion, an inductive coil is realized. [0120] It is noted that the conductive trace portions may be replaced with a dielectric to provide a capacitive connection between the multiple or stacked loops.

[0121] It is noted that the individual loops (4000, 4100, 4200, and 4300) may be formed to have distinct shapes and areas.

[0122] As illustrated in Figure 10, a substrate 100 has formed thereon conductive traces 1300, composed of film coatings of metal or any thin pliable conductive material.

The traces 1300 are formed so as to create a single spiraling resonance coil that will be used in forming a LC circuit that is tuned to the desired frequency of magnetic resonance imaging or other desired frequency. It is noted that the traces 1300 may also be formed so as to create a single spiraling resonance coil that will be used in forming a

RLC circuit that is tuned to the desired frequency of magnetic resonance imaging or other desired frequency.

[0123] In this embodiment, the "resistor" is the "conductive" material or conductive traces 1300. The resistor value is controlled by the dimensions of the conductor as well as the material selected for the conductor. Also, the material for the conductor may vary along the length of the tracing forming the inductor, thereby providing a resistive parameter to the circuit.

[0124] The degree of resonance or 'Q' of either the formed LC or formed RLC circuit is a degree of resonance at the Lamar frequency of the magnetic resonance imaging system to permit clinically effective imaging inside the lumen of the stent.

[0125] The capacitance is realized by the capacitance by the overlapping of the end portions of the traces 1300 in region 1350 when the substrate 100 is wrapped into a substantially cylinder shape, as illustrated in Figure 11 , to form a sleeve. The end portions of the traces 1300 are formed so that the end portions are aligned as illustrated by dashed box 1375.

[0126] The traces 1300 are insulated by an insulative dielectric material (not shown) so that when the end portions of the traces 1300 in region 1350 overlap, due to the wrapping of the substrate 100 as illustrated in Figure 11 , the overlapped portions of the traces 1300 form a capacitor. The capacitance of the trace formed capacitor in region

1350 is variable as the wrapping of the substrate 100 becomes tighter (contracts) or is loosened (expands).

[0127] As noted above, the stent must enable imaging and visualization of the inner lumen of an implanted stent by means of a magnetic resonance imaging technique, thus the stent must have an associated resonance circuit that is tuned to the desired frequency of magnetic resonance. The substrate sleeve of Figures 10 and 11 provides the resonance circuit that is tuned to the desired frequency of magnetic resonance independent of the stent. The resonance circuit of Figures 10 and 11 can also be designed to complement the resonance frequency of an implanted stent so that the combination of the resonance circuit, the implanted stent, and surrounding environmental conditions has an effective resonance frequency that is substantially equal to the operating frequency of the magnetic resonance imaging scanner. It is noted that the resonance circuit can be designed to complement the resonance frequency of any implanted device having a lumen to be imaged so that the combination of the resonance circuit, the implanted device, and surrounding environmental conditions has an effective resonance frequency that is substantially equal to the operating frequency of the magnetic resonance imaging scanner. It is further noted that for all embodiments disclosed herein, the resonance circuits can also be designed to complement the resonance frequency of an implanted device so that the combination of the resonance circuit, the implanted device, and surrounding environmental conditions has an effective resonance frequency that is substantially equal to the operating frequency of the magnetic resonance imaging scanner. It is also noted that for all embodiments disclosed herein, the resonance circuits and the combination of the resonance circuit, the implanted device, and surrounding environmental conditions may be tuned to have an effective resonance frequency that is substantially equal to a harmonic or sub-harmonic frequency of the operating frequency of the magnetic resonance imaging scanner.

[0128] To be in resonance, the substrate sleeve of Figures 10 and 11 must include an LC or RLC circuit that is tuned to the desired frequency of magnetic resonance or other desired frequency.

[0129] In this embodiment, the traces 1300 are formed to create the inductive properties and the overlapping of the traces, when the sleeve is wrapped, creates the capacitive properties. Again, it is noted that a resistive value related to the dimensions of the conductor as well as the material selected for the conductor may be included in the resonance circuit of the substrate sleeve.

[0130] It is noted that the combination of the decreasing of the overall inductance of the resonance circuit of the substrate sleeve and the increasing of the overall capacitance of the resonance circuit of the substrate sleeve may also enable the maintaining of resonance within a desired bandwidth, which may or may not be in resonance with the magnetic resonance imaging scanner.

[0131] It is also noted that the combination of the increasing of the overall inductance of the resonance circuit of the substrate sleeve and the decreasing of the overall capacitance of the resonance circuit of the substrate sleeve may also enable the maintaining of resonance within a desired bandwidth, which may or may not be in resonance with the magnetic resonance imaging scanner.

[0132] The substrate 100 may be a biodegradable substrate that essentially decomposes once the stent is positioned in the body. It is further noted that the substrate 100 may be thermally degradable, chemically degradable, and/or optically degradable. The substrate 100 may also include drugs or medical agents that are therapeutically released upon the decomposition of the substrate. Lastly, the substrate 100 and included resonance circuit are expandable without resulting in breakage. It is noted that the substrate or support web 100, may be biodegradable and may have adhesive properties useful during manufacture and implantation; however, after biodegradation, the applied conductive traces 1300 retain an electrically insulating coating or sheath that prevents unwanted shorting even under repeated flexing of the stent/circuit device in the body.

[0133] As illustrated in Figure 18, a substrate 100 has formed thereon conductive traces (3000, 3100, 3200, and 3300) composed of film coatings of metal or any thin pliable conductive material. The traces are formed so as to create independent spiraling resonance coils tuned to different frequencies. It is noted that these frequencies may be harmonics. The spiraling coils are formed by the traces running on top of each other with an insulating material therebetween. It is noted that the insulating material may be a dielectric to provide capacitance.

[0134] The conductive traces (3000 3100, 3200, and 3300) are used in forming a LC circuit that is tuned to the desired frequency of magnetic resonance imaging or other desired frequency. It is noted that the traces may also be formed so as to create independent resonance coils that will be used in forming a RLC circuit that is tuned to the desired frequency of magnetic resonance imaging or other desired frequency. [0135] In this embodiment, the "resistor" is the "conductive" material or conductive traces. The resistor value is controlled by the dimensions of the conductor as well as the material selected for the conductor. Also, the material for the conductor may vary along the length of the tracing forming the inductor, thereby providing a resistive parameter to the circuit.

[0136] The degree of resonance or 'Q' of either the formed LC or formed RLC circuit is a degree of resonance at the Lamar frequency of the magnetic resonance imaging system to permit clinically effective imaging inside the lumen of the stent.

[0137] The capacitance is realized by the capacitance by the overlapping of the end portions of the traces when the substrate 100 is wrapped into a substantially cylinder shape, as illustrated in Figure 19, to form a sleeve. The end portions of the traces are formed so that the end portions are aligned.

[0138] The traces are insulated by an insulative dielectric material (not shown) so that when the end portions of the traces overlap, due to the wrapping of the substrate

100 as illustrated in Figure 19, the overlapped portions of the traces form a capacitor.

The capacitance of the trace formed capacitor is variable as the wrapping of the substrate 100 becomes tighter (contracts) or is loosened (expands).

[0139] As noted above, the stent must enable imaging and visualization of the inner lumen of an implanted stent by means of a magnetic resonance imaging technique, thus the stent must have an associated resonance circuit that is tuned to the desired frequency of magnetic resonance. The substrate sleeve of Figures 18 and 19 provides the resonance circuit that is tuned to the desired frequency of magnetic resonance independent of the stent. The resonance circuit of Figures 18 and 19 can also be designed to complement the resonance frequency of an implanted stent so that the combination of the resonance circuit, the implanted stent, and surrounding environmental conditions has an effective resonance frequency that is substantially equal to the operating frequency of the magnetic resonance imaging scanner. It is noted that the resonance circuit can be designed to complement the resonance frequency of any implanted device having a lumen to be imaged so that the combination of the resonance circuit, the implanted device, and surrounding environmental conditions has an effective resonance frequency that is substantially equal to the operating frequency of the magnetic resonance imaging scanner.

[0140] To be in resonance, the substrate sleeve of Figures 18 and 19 must include an LC or RLC circuit that is tuned to the desired frequency of magnetic resonance or other desired frequency.

[0141] In this embodiment, the traces are formed to create the inductive properties and the overlapping of the traces, when the sleeve is wrapped, creates the capacitive properties. Again, it is noted that a resistive value related to the dimensions of the conductor as well as the material selected for the conductor may be included in the resonance circuit of the substrate sleeve.

[0142] It is noted that the combination of the decreasing of the overall inductance of the resonance circuit of the substrate sleeve and the increasing of the overall capacitance of the resonance circuit of the substrate sleeve may also enable the maintaining of resonance within a desired bandwidth, which may or may not be in resonance with the magnetic resonance imaging scanner.

[0143] It is also noted that the combination of the increasing of the overall inductance of the resonance circuit of the substrate sleeve and the decreasing of the overall capacitance of the resonance circuit of the substrate sleeve may also enable the maintaining of resonance within a desired bandwidth, which may or may not be in resonance with the magnetic resonance imaging scanner.

[0144] As illustrated in Figure 13, a substrate 100 has formed thereon conductive traces 1300, composed of film coatings of metal or any thin pliable conductive material.

The traces 1300 are formed so as to create a single spiraling resonance coil that will be used in forming a LC circuit that is tuned to the desired frequency of magnetic resonance imaging or other desired frequency. It is noted that the traces 1300 may also be formed so as to create a resonance coil that will be used in forming a RLC circuit that is tuned to the desired frequency of magnetic resonance imaging or other desired frequency.

[0145] In this embodiment, the "resistor" is the "conductive" material or conductive traces 1300. The resistor value is controlled by the dimensions of the conductor as well as the material selected for the conductor. Also, the material for the conductor may vary along the length of the tracing forming the inductor, thereby providing a resistive parameter to the circuit.

[0146] The degree of resonance or 'Q' of either the formed LC or formed RLC circuit is a degree of resonance at the Lamar frequency of the magnetic resonance imaging system to permit clinically effective imaging inside the lumen of the stent.

[0147] The capacitance is realized by the capacitance by the overlapping of the end portions of the traces 1300 in region 1350 when the substrate 100 is wrapped into a substantially cylinder shape to form a sleeve. The end portions of the traces 1300, as illustrated in Figure 13, are formed so that the end portions are aligned as illustrated by dashed box 1375 and have a shape that enables a non-linear variability in the capacitance as the substrate 100 becomes tighter (contracts) or is loosened (expands). [0148] The traces 1300 are insulated by an insulative dielectric material (not shown) so that when the end portions of the traces 1300 in region 1350 overlap, due to the wrapping of the substrate 100, the overlapped portions of the traces 1300 form a capacitor. The capacitance of the trace formed capacitor in region 1350 is variable as the wrapping of the substrate 100 becomes tighter (contracts) or is loosened (expands). [0149] As noted above, the stent must enable imaging and visualization of the inner lumen of an implanted stent by means of a magnetic resonance imaging technique, thus the stent must have an associated resonance circuit that is tuned to the desired frequency of magnetic resonance. The substrate sleeve of Figure 13 provides the resonance circuit that is tuned to the desired frequency of magnetic resonance independent of the stent.

[0150] To be in resonance, the substrate sleeve of Figure 13 must include an LC or RLC circuit that is tuned to the desired frequency of magnetic resonance or other desired frequency.

[0151] In this embodiment, the traces are formed to create the inductive properties and the overlapping of the traces, when the sleeve is wrapped, creates the capacitive properties. Again, it is noted that a resistive value related to the dimensions of the conductor as well as the material selected for the conductor may be included in the resonance circuit of the substrate sleeve.

[0152] It is noted that as the wrapping of the substrate 100 becomes tighter (contracts), the overall inductance of the resonance circuit of the substrate sleeve decreases, but the overall capacitance of the resonance circuit of the substrate sleeve non-linearly increases because the area of the overlapping trace portions becomes greater, thereby substantially maintaining resonance with the desired frequency of magnetic resonance imaging or other desired frequency.

[0153] It is noted that the combination of the decreasing of the overall inductance of the resonance circuit of the substrate sleeve and the increasing of the overall capacitance of the resonance circuit of the substrate sleeve may also enable the maintaining of resonance within a desired bandwidth, which may or may not be in resonance with the magnetic resonance imaging scanner.

[0154] It is also noted that as the wrapping of the substrate 100 becomes looser (expands), the overall inductance of the resonance circuit of the substrate sleeve increases, but the overall capacitance of the resonance circuit of the substrate sleeve non-linearly decreases because the area of the overlapping trace portions becomes lesser, thereby substantially maintaining resonance with the desired frequency of magnetic resonance imaging or other desired frequency.

[0155] It is noted that the combination of the increasing of the overall inductance of the resonance circuit of the substrate sleeve and the decreasing of the overall capacitance of the resonance circuit of the substrate sleeve may also enable the maintaining of resonance within a desired bandwidth, which may or may not be in resonance with the magnetic resonance imaging scanner.

[0156] The substrate 100 may be a biodegradable substrate that essentially decomposes once the stent is positioned in the body. It is further noted that the substrate 100 may be thermally degradable, chemically degradable, and/or optically degradable. The substrate 100 may also include drugs or medical agents that are therapeutically released upon the decomposition of the substrate. Lastly, the substrate 100 is expandable without resulting in breakage. It is noted that the substrate or support web 100, may be biodegradable and may have adhesive properties useful during manufacture and implantation; however, after biodegradation, the applied conductive traces 1300 retain an electrically insulating coating or sheath that prevents unwanted shorting even under repeated flexing of the stent/circuit device in the body. [0157] As illustrated in Figure 15, a substrate 100 has formed thereon conductive traces 1400, composed of film coatings of metal or any thin pliable conductive material. The traces 1400 have zig-zag shape portion 1425 to prevent circuit breakage either during crimping or re-expansion.

[0158] The traces 1400 are formed so as to create a single spiral ing resonance coil that will be used in forming a LC circuit that is tuned to the desired frequency of magnetic resonance imaging or other desired frequency. It is noted that the traces 1400 may also be formed so as to create a resonance coil that will be used in forming a RLC circuit that is tuned to the desired frequency of magnetic resonance imaging or other desired frequency.

[0159] In this embodiment, the "resistor" is the "conductive" material or conductive traces 1400. The resistor value is controlled by the dimensions of the conductor as well as the material selected for the conductor. Also, the material for the conductor may vary along the length of the tracing forming the inductor, thereby providing a resistive parameter to the circuit. [0160] The degree of resonance or 'Q' of either the formed LC or formed RLC circuit is a degree of resonance at the Lamar frequency of the magnetic resonance imaging system to permit clinically effective imaging inside the lumen of the stent. [0161] In an optional embodiment, as illustrated in Figure 16, the traces 1400 may be formed to create sub-coils 1450. The sub-coils 1450 are formed by a finer meandering of the traces 1400 on the substrate 100. These sub-coils 1450 may be formed in any of the various embodiments discussed above.

[0162] The capacitance is realized by the capacitance by the overlapping of the end portions of the traces 1400 in region 1350 when the substrate 100 is wrapped into a substantially cylinder shape to form a sleeve. The end portions of the traces 1400, as illustrated in Figure 13, are formed so that the end portions are aligned as illustrated by dashed box 1375 and have a shape that enables a non-linear variability in the capacitance as the substrate 100 becomes tighter (contracts) or is loosened (expands). [0163] The traces 1400 are insulated by an insulative dielectric material (not shown) so that when the end portions of the traces 1400 in region 1350 overlap, due to the wrapping of the substrate 100, the overlapped portions of the traces 1400 form a capacitor. The capacitance of the trace formed capacitor in region 1350 is variable as the wrapping of the substrate 100 becomes tighter (contracts) or is loosened (expands). [0164] As noted above, the stent must enable imaging and visualization of the inner lumen of an implanted stent by means of a magnetic resonance imaging technique, thus the stent must have an associated resonance circuit that is tuned to the desired frequency of magnetic resonance. The substrate sleeve of Figure 13 provides the resonance circuit that is tuned to the desired frequency of magnetic resonance independent of the stent. The resonance circuit of Figure 13 can also be designed to complement the resonance frequency of an implanted stent so that the combination of the resonance circuit, the implanted stent, and surrounding environmental conditions has an effective resonance frequency that is substantially equal to the operating frequency of the magnetic resonance imaging scanner. It is noted that the resonance circuit can be designed to complement the resonance frequency of any implanted device having a lumen to be imaged so that the combination of the resonance circuit, the implanted device, and surrounding environmental conditions has an effective resonance frequency that is substantially equal to the operating frequency of the magnetic resonance imaging scanner. [0165] To be in resonance, the substrate sleeve of Figure 13 must include an LC or

RLC circuit that is tuned to the desired frequency of magnetic resonance or other desired frequency.

[0166] In this embodiment, the traces are formed to create the inductive properties and the overlapping of the traces, when the sleeve is wrapped, creates the capacitive properties. Again, it is noted that a resistive value related to the dimensions of the conductor as well as the material selected for the conductor may be included in the resonance circuit of the substrate sleeve.

[0167] It is noted that as the wrapping of the substrate 100 becomes tighter

(contracts), the overall inductance of the resonance circuit of the substrate sleeve decreases, but the overall capacitance of the resonance circuit of the substrate sleeve non-linearly increases because the area of the overlapping trace portions becomes greater, thereby substantially maintaining resonance with the desired frequency of magnetic resonance imaging or other desired frequency.

[0168] It is noted that the combination of the decreasing of the overall inductance of the resonance circuit of the substrate sleeve and the increasing of the overall capacitance of the resonance circuit of the substrate sleeve may also enable the maintaining of resonance within a desired bandwidth, which may or may not be in resonance with the magnetic resonance imaging scanner.

[0169] It is also noted that as the wrapping of the substrate 100 becomes looser

(expands), the overall inductance of the resonance circuit of the substrate sleeve increases, but the overall capacitance of the resonance circuit of the substrate sleeve non-linearly decreases because the area of the overlapping trace portions becomes lesser, thereby substantially maintaining resonance with the desired frequency of magnetic resonance imaging or other desired frequency.

[0170] It is noted that the combination of the decreasing of the overall inductance of the resonance circuit of the substrate sleeve and the increasing of the overall capacitance of the resonance circuit of the substrate sleeve may also enable the maintaining of resonance within a desired bandwidth, which may or may not be in resonance with the magnetic resonance imaging scanner.

[0171] The substrate 100 may be a biodegradable substrate that essentially decomposes once the stent is positioned in the body. It is further noted that the substrate 100 may be thermally degradable, chemically degradable, and/or optically degradable. The substrate 100 may also include drugs or medical agents that are therapeutically released upon the decomposition of the substrate. Lastly, the substrate 100 is expandable without resulting in breakage. It is noted that the substrate or support web 100, may be biodegradable and may have adhesive properties useful during manufacture and implantation; however, after biodegradation, the applied conductive traces 1400 retain an electrically insulating coating or sheath that prevents unwanted shorting even under repeated flexing of the stent/circuit device in the body. [0172] As illustrated in Figure 12, a substrate 1000 is formed such that it wraps back into itself. This substrate includes conductive traces composed of film coatings of metal or any thin pliable conductive material. The traces are formed so as to create a single spiraling resonance coil that will be used in forming a LC circuit that is tuned to magnetic resonance imaging parameters. It is noted that the traces may also be formed so as to create a spiraling resonance coil that will be used in forming a RLC circuit that is tuned to magnetic resonance imaging parameters. The degree of resonance or 'Q' of either the formed LC or formed RLC circuit is a degree of resonance at the Lamar frequency of the magnetic resonance imaging system to permit clinically effective imaging inside the lumen of the stent.

[0173] The capacitance is realized by the capacitance by the overlapping of the end portions of the traces as the substrate 1000 is wrapped back into itself to form a sleeve. In other words, the substrate 1000 includes a closed end and an open end, wherein the closed end and open end are substantially parallel with the axis of the created sleeve. In this embodiment, the closed end is positioned within the open end of the substrate 1000. It is noted that either the closed end, open end, or both ends may include members (not shown) to prevent the closed end from being positioned outside (or without) the confines of the open end and open end.

[0174] The traces are insulated by an insulative dielectric material (not shown) so that when the end portions of the traces overlap, due to the wrapping of the substrate 1000, the overlapped portions of the traces form a capacitor. The capacitance of the trace formed capacitor is variable as the wrapping of the substrate 1000 becomes tighter (contracts) or is loosened (expands).

[0175] As noted above, the stent must enable imaging and visualization of the inner lumen of an implanted stent by means of a magnetic resonance imaging technique, thus the stent must have an associated resonance circuit that is tuned to the desired frequency of magnetic resonance. The substrate sleeve of Figure 12 provides the resonance circuit that is tuned to the desired frequency of magnetic resonance independent of the stent. The resonance circuit of Figure 12 can also be designed to complement the resonance frequency of an implanted stent so that the combination of the resonance circuit, the implanted stent, and surrounding environmental conditions has an effective resonance frequency that is substantially equal to the operating frequency of the magnetic resonance imaging scanner. It is noted that the resonance circuit can be designed to complement the resonance frequency of any implanted device having a lumen to be imaged so that the combination of the resonance circuit, the implanted device, and surrounding environmental conditions has an effective resonance frequency that is substantially equal to the operating frequency of the magnetic resonance imaging scanner.

[0176] To be in resonance, the substrate sleeve of Figure 12 must include an LC or RLC circuit that is tuned to the desired frequency of magnetic resonance or other desired frequency.

[0177] In this embodiment, the traces are formed to create the inductive properties and the overlapping of the traces, when the sleeve is wrapped, creates the capacitive properties. Again, it is noted that a resistive value related to the dimensions of the conductor as well as the material selected for the conductor may be included in the resonance circuit of the substrate sleeve.

[0178] It is noted that as the wrapping of the substrate 1000 becomes tighter (contracts), the overall inductance of the substrate sleeve decreases, but the overall capacitance of the substrate sleeve increases because the area of the overlapping trace portions becomes greater, thereby substantially maintaining resonance with the desired frequency of magnetic resonance imaging or other desired frequency. [0179] It is noted that the combination of the decreasing of the overall inductance of the resonance circuit of the substrate sleeve and the increasing of the overall capacitance of the resonance circuit of the substrate sleeve may also enable the maintaining of resonance within a desired bandwidth, which may or may not be in resonance with the magnetic resonance imaging scanner.

[0180] It is also noted that as the wrapping of the substrate 1000 becomes looser (expands), the overall inductance of the substrate sleeve increases, but the overall capacitance of the substrate sleeve decreases because the area of the overlapping trace portions becomes lesser, thereby substantially maintaining resonance with the desired frequency of magnetic resonance imaging or other desired frequency. [0181] It is noted that the combination of the decreasing of the overall inductance of the resonance circuit of the substrate sleeve and the increasing of the overall capacitance of the resonance circuit of the substrate sleeve may also enable the maintaining of resonance within a desired bandwidth, which may or may not be in resonance with the magnetic resonance imaging scanner.

[0182] The substrate 1000 may be a biodegradable substrate that essentially decomposes once the stent is positioned in the body. It is further noted that the substrate 1000 may be thermally degradable, chemically degradable, and/or optically degradable. The substrate 1000 may also include drugs or medical agents that are therapeutically released upon the decomposition of the substrate. Lastly, the substrate 1000 is expandable without resulting in breakage. It is noted that the substrate or support web 1000, may be biodegradable and may have adhesive properties useful during manufacture and implantation; however, after biodegradation, the applied conductive traces retain an electrically insulating coating or sheath that prevents unwanted shorting even under repeated flexing of the stent/circuit device in the body. [0183] Figure 14 illustrates a sleeve wrapped around a stent 2000. The sleeve includes a substrate 3000 has formed thereon a LC circuit 4000 that is tuned to magnetic resonance imaging parameters.

[0184] As noted above, the stent must enable imaging and visualization of the inner lumen of an implanted stent by means of a magnetic resonance imaging technique, thus the stent must have an associated resonance circuit that is tuned to the desired frequency of magnetic resonance. The substrate sleeve of Figure 14 provides the resonance circuit that is tuned to the desired frequency of magnetic resonance independent of the stent. The resonance circuit of Figure 14 can also be designed to complement the resonance frequency of an implanted stent so that the combination of the resonance circuit, the implanted stent, and surrounding environmental conditions has an effective resonance frequency that is substantially equal to the operating frequency of the magnetic resonance imaging scanner. It is noted that the resonance circuit can be designed to complement the resonance frequency of any implanted device having a lumen to be imaged so that the combination of the resonance circuit, the implanted device, and surrounding environmental conditions has an effective resonance frequency that is substantially equal to the operating frequency of the magnetic resonance imaging scanner. [0185] To be in resonance, the substrate sleeve of Figure 14 must include an LC or RLC circuit 4000 that is tuned to the desired frequency of magnetic resonance or other desired frequency.

[0186] In this embodiment, the traces are formed to create the inductive properties and the overlapping of the traces, when the sleeve is wrapped, creates the capacitive properties. Again, it is noted that a resistive value related to the dimensions of the conductor as well as the material selected for the conductor may be included in the resonance circuit of the substrate sleeve.

[0187] It is noted that as the wrapping of the substrate 3000 becomes tighter (contracts), the overall inductance of the substrate sleeve decreases, but the overall capacitance of the substrate sleeve non-linearly increases because the area of the overlapping trace portions becomes greater, thereby substantially maintaining resonance with the desired frequency of magnetic resonance imaging or other desired frequency.

[0188] It is noted that the combination of the decreasing of the overall inductance of the resonance circuit of the substrate sleeve and the increasing of the overall capacitance of the resonance circuit of the substrate sleeve may also enable the maintaining of resonance within a desired bandwidth, which may or may not be in resonance with the magnetic resonance imaging scanner.

[0189] It is also noted that as the wrapping of the substrate 3000 becomes looser (expands), the overall inductance of the substrate sleeve increases, but the overall capacitance of the substrate sleeve non-linearly decreases because the area of the overlapping trace portions becomes lesser, thereby substantially maintaining resonance with the desired frequency of magnetic resonance imaging or other desired frequency. [0190] It is noted that the combination of the decreasing of the overall inductance of the resonance circuit of the substrate sleeve and the increasing of the overall capacitance of the resonance circuit of the substrate sleeve may also enable the maintaining of resonance within a desired bandwidth, which may or may not be in resonance with the magnetic resonance imaging scanner.

[0191] The substrate 3000 may be a biodegradable substrate that essentially decomposes once the stent is positioned in the body. It is further noted that the substrate 3000 may be thermally degradable, chemically degradable, and/or optically degradable. The substrate 3000 may also include drugs or medical agents that are therapeutically released upon the decomposition of the substrate. Lastly, the substrate 3000 is expandable without resulting in breakage.

[0192] Figures 5 and 6 illustrate a manufacturing process for creating the sleeve substrate of the present invention. As illustrated in Figure 6, an inductive resonance circuit is etched in foil to form traces 330. The traces 330 are folded along lines 150 and 155 to create a substantially flat resonance inductive circuit, as illustrated in Figure 5. The folding of the etched foil enables efficient production of the traces without worry of shorting and allows the coil traces to cross over each other without short because the traces are coated in an insulative material before folding. The material may also be a dielectric, thereby providing some capacitance to the resonance circuit etched in the foil. The folding also enables the geometry of the resonance circuit topological^ possible. [0193] Figure 7 illustrates another approach of manufacture. The manufacture device 200 feeds an insulated thin wire conductor 230, using drivers 210 to a substrate (not shown). The insulated thin wire conductor 230 is heated by heaters 220. The heating of the insulated thin wire conductor 230 provides an adhesive property for bonding the insulated thin wire conductor 230 to the substrate. The bond is completed by the cool roller 250 which is attached to the tool 200 by ring 240. [0194] For any of the embodiments described above, the resonance circuits of Figure 4 (100A, 100B, 100C, 100D, 100E, 100F....) may be placed upon a web 400 to provide transport. The web 400 may be a biodegradable substrate that essentially decomposes once the stent is positioned in the body. The web 400 may also include drugs or medical agents that are therapeutically released upon the decomposition of the substrate. Lastly, the web 400 is expandable without resulting in breakage. It is noted that the substrate or support web 400, may be biodegradable and may have adhesive properties useful during manufacture and implantation; however, after biodegradation, the applied resonance circuits retain an electrically insulating coating or sheath that prevents unwanted shorting even under repeated flexing of the stent/circuit device in the body. It is further noted that the support web 400 may be thermally degradable, chemically degradable, and/or optically degradable.

[0195] It is noted that the end portions of the traces may have various shapes so as to provide the proper variability in the capacitance, whether it be linear variability, nonlinear variability or gradual variability, etc. [0196] It is also noted that the traces can be formed to provide variability in the inductance, whether it be linear variability, non-linear variability or gradual variability, etc.

[0197] In the various examples above, the present invention is directed to the attachment of a secondary formed structure (resonance circuit sleeve) to a primary formed structure (medical device and/or stent). This attachment of a secondary formed structure can provide imaging and visualization of the inner lumen of the primary formed structure by means of a magnetic resonance imaging technique wherein the secondary formed structure is independent of the primary formed structure's architecture. The resonance circuit can also be designed to complement the resonance frequency of an implanted primary formed structure so that the combination of the resonance circuit, the implanted primary formed structure, and surrounding environmental conditions has an effective resonance frequency that is substantially equal to the operating frequency of the magnetic resonance imaging scanner. It is noted that the resonance circuit can be designed to complement the resonance frequency of any primary formed structure having a lumen to be imaged so that the combination of the resonance circuit, the implanted primary formed structure, and surrounding environmental conditions has an effective resonance frequency that is substantially equal to the operating frequency of the magnetic resonance imaging scanner.

[0198] Moreover, the resonance circuit sleeve of the present invention provides imaging and visualization of the inner lumen of the primary formed structure (medical device and/or stent) by means of a magnetic resonance imaging technique wherein the resonance circuit sleeve of the present invention is independent of the primary formed structure's architecture.

[0199] As noted above, the resonance circuit sleeve is to be realized over an expanded stent. Initially, the sleeve is placed around an expanded stent. The sleeve may then be shrink-wrapped around the stent so that the stent is reduced in size for proper insertion into the body. The sleeve may also be crimped with the stent therein. The traces are shaped in the crimped section so as to minimize stress during crimping, shrink-wrapping, and/or and expansion.

[0200] It is noted that the substrate onto which the coil/circuit patterns are placed may initially be a cylinder. After the patterns of materials are placed upon the cylinder substrate, the cylinder is cut/slit longitudinally. By starting with a cylinder rather than a flat substrate, the material need not require the same flexibility as material need to create the sleeve created as a flat surface.

[0201] It is also noted that although the various embodiments described above refer to the utilization of the resonance circuit sleeve with a stent, the concepts of the present invention are applicable to other situations. For example, the resonance circuit sleeve of the present invention may be utilized with other devices of similar construction that are implanted in the body, such as implantable devices having conductive structures that exhibit a Faraday Cage effect and that inhibit effective internal magnetic resonance imaging. Moreover, the resonance circuit sleeve of the present invention may be utilized with vena cava filters, heart valves, and any interventional surgical device that may exhibit a Faraday Cage effect and that inhibit effective internal magnetic resonance imaging

[0202] Furthermore, it is noted that the resonance circuit sleeve can be applied to the stent before the drug eluting coating is applied. The substrate web of the resonance circuit sleeve would be dissolved prior to the drug coating. For example, the resonance circuit sleeve may have a dual insulation on the circuit; inner layer having a higher melt temperature and the outer acting as an adhesive when heated to a more modest temperature. In this example, any substrate web would be dissolved after adhesion of the resonance circuit to stent.

[0203] It is further noted that the resonance circuit may be created on a pre-formed tube rather than as a flat circuit that is wrapped to form a tube. In the various embodiments described above, adhesive may be used to help in manufacture and in retention during implantation.

[0204] More specifically, Figure 22 shows a stent assembly 5000 including a stent 5002 wholly or partially inserted into a cylinder membrane 5004, which may be a stent graft. The cylinder membrane 5004 has formed thereon, a circuit having one or more conductive traces 5006 forming a rectangular (or other shaped) coil and a capacitor. The capacitor is formed by overlapping two ends of the conductive trace 5006 used to form the coil. The overlapped ends of the conductive trace 5006 are separated by a dielectric material.

[0205] As illustrated in Figure 22, the conductive traces 5006 form a rectangular shaped coil. The rectangular shaped coil has two end edges 5008 and 5010 which may have a zig-zag pattern to facilitate cylindrical radial expansion during the radial expansion of the stent 5002 and membrane 5004. [0206] The conductive traces 5006 may form a coil having one or more coil loops. The traces 5006 may be formed side-by-side with each other or may be formed on top of each other with an electrically insulative material interposed to prevent shorting of the coil's loops.

[0207] Figure 23 illustrates a stent assembly 6000 having two resonant circuits (6006 & 6008) on a cylinder membrane 6002 around a stent 6004. The circuits (6006 & 6008) are oriented to be approximately 90 degrees to each other. At cross-over points (6010 & 6020) there is interposed an electrically insulative material.

[0208] Figure 24 illustrates a thin film substrate 6502 onto which two resonant circuits (6504 & 6506) are constructed. These circuits (6504 & 6506) each include a conductive trace to form a coil. Each coiled conductive trace has two ends (its start and stop ends). For each of the coils, overlapping the two ends of the coil trace with a dielectric interposed forms the capacitor of the circuit. The circuits (6504 & 6506) are tuned to resonate at or about the operating frequency of a magnetic resonance imaging scanner. More specifically, the circuits (6504 & 6506) are tuned so that when the circuits (6504 & 6506) are placed around a stent (or other medical device) and inserted into the body, the circuits (6504 & 6506) resonate at or near the operating frequency of the magnetic resonant imaging scanner's frequency.

[0209] As noted above, the two circuits (6504 & 6506) overlap each other (6510 & 6512). These circuits are electrically insulated from each other at these points (6510 & 6512) by placing an electrical insulative material between the conductive traces. [0210] Figure 25 illustrates the two circuits (6504 & 6506) being so positioned on the film 6502 such that when the film 6502 is wrapped around a stent 6520 the two formed coil loops are orientated at or approximately at 90 degrees to each other. [0211] Figure 26 illustrates the formation of a capacitor for a circuit wherein a stent circuit assembly 7000 includes a substrate 7002 onto which a conductive trace 7004 is formed. The conductive trace 7004 has a first end 7008 and a second end 7010. The two ends (7008 & 7010) of the conductive trace 7004 overlap to form a capacitor 7006. [0212] Referring to Figure 27, which is a side view of the stent circuit assembly 7000 of Figure 26, the conductive trace 7004 is formed on the substrate 7002. A capacitor 7006 is formed by the overlapping of the two ends (7008 & 7010) of the conductive trace 7004 with a dielectric material 7020 positioned between the two ends (7008 & 7010). [0213] Figure 28 illustrates a substrate 100 having a resonance coil 8500 with multiple (non-stacked) loops formed thereon. More specifically, a trace 8000 is looped to form multiple (non-stacked) loops. An area 8100, at a first end 8300 of the trace 8000 may form a capacitor when the first end 8300 of the trace 8000 overlaps a second end 8400 of the trace 8000. It is further noted that at crossover points 8200, an insulative material is interposed between the over and under traces to prevent an electrical short. [0214] It is further noted that the resonance sleeve of the present invention may also be formed around a stent that has already been crimped into its smaller shape. It is further noted that the described substrates and/or web may be the covering material for a medical device. For example, the described substrates and/or web may be the covering material for a covered AAA-stent graft.

[0215] As noted above, Figures 29-33 illustrate conventional embodiments of a stent structure that includes disruptions of the electrically conductive pathways formed by the stents geometrical structure, i.e. the "struts" of the stent, to reduce or eliminate the shielding effect.

[0216] As illustrated in Figures 29-33, the filler material is a material of high electrical impedance, such as another metal or metal alloy, ceramic, or polymer. The stent is then fabricated as before. The finished stent is mechanically strong, while providing a region of high resistance that runs the length of the stent.

[0217] On the other hand, metallic tubes can also be formed by extrusion. The extrusion process is modified to enable a second material to be injected into the extruded tube, along its long axis, as it is extruded. The end result is a region of high resistance that runs the length of the stent.

[0218] Moreover, metallic tubes can also be formed by utilizing interlocking mechanical "tabs" formed into the ends of flat pieces of metal that are uniformly curved until opposing sides of the metal come into contact with and are joined to each other. A high electrical resistance material is placed between the mechanical tabs to create a region of high resistance that runs the length of the tube and subsequent stent. [0219] Furthermore, the stent of Figures 29-33 can be partially formed by selectively removing materials from metallic tubes to form a portion of the stents complex geometrical structure. The partially formed stent structure contains two key features; the metallic portions of partially finished interlocking tabs and optionally non-functional metal struts that serve to hold together the partially finished interlocking tabs. The partially finished stent is then subject to a second manufacturing step, such as insert molding, to add a high electrical resistance "filler" material (e.g. polymer or metal alloy) around the partially finished interlocking tab, thereby forming a mechanical joint. A third, optional, manufacturing step then removes the non-functional metal struts that initially served to hold together the partially finished interlocking tabs. The high electrical resistance filler material then serves as a region or regions of high electrical resistance. [0220] Lastly, the stent of Figures 29-33 can be coated on the inside and/or outside surface with a high electrical resistance material. The stent is then fabricated, as before, by selectively removing materials from metallic tubes but in such a way that one or more sections of the high electrical resistance material remains in place and serves to secure together one or more adjacent portions of the stent, thereby forming a region or regions of high electrical resistance.

[0221] It is noted that by applying an electrically resonating circuit to the surface of the stent, such as a "saddle" coil, the electrically resonating circuit can enable the interior of the stent to be imaged using magnetic resonance imaging. However, integrating such a coil into the stent is very difficult to achieve in practice. [0222] One embodiment that integrates such a coil would be a stent having a coil of the resonating circuit being applied to the mechanical struts of the stent. The coil and the coil's return path follow the stent struts.

[0223] In another embodiment, the coil of the resonating circuit is applied, as before, to the mechanical struts of the stent. However, the coil's return path is integrated into a "seam" running along the long axis of the stent. As used herein, this seam includes the return path which is integrated into the welded joint running along the long axis of the metallic tube from which the stent is fabricated.

[0224] In another embodiment, the metallic tube, from which the stent is fabricated, is coated on the inside and/or outside surface(s) by two materials; a high electrical resistance material that electrically insulates from the stent a second electrically conductive material. The stent is then fabricated, as before, by selectively removing materials from metallic tubes but in such a way that leaves the aforementioned coatings intact, which then form the coil and (optionally) capacitive portions of the resonating circuit.

[0225] Figures 34-37 illustrate further examples of sleeves for a stent to enable the stent to be interiorly imaged, non-invasively, using magnetic resonance imaging. The substrate may be a drug eluting material and may have minimum material to provide support for the circuit. In Figure 34, two loops are formed with a capacitor platform. Figure 35 illustrates a substrate that has been cutout so that the substrate carries only the circuit and the capacitor is integrated in the coil or loop construction. More specifically, the capacitor is formed by overlapping the ends of the trace forming the loop wherein a dielectric material is formed between the overlapping ends of the trace. [0226] Figures 36 and 37, the loops are formed such two loops are at 90 degrees to each other when wrapped, as illustrated in Figure 37. As with Figure 35, the capacitor is integrated in the coil or loop construction of Figures 36 and 37. More specifically, the capacitor is formed by overlapping the ends of the trace forming the loop wherein a dielectric material is formed between the overlapping ends of the trace. [0227] Figure 38 illustrates models of stents according to the concepts of the present invention. In one embodiment, the stent has fourteen rings and four connectors. In the second embodiment, the stent has two rings and four connectors. [0228] Figure 39 shows a graph of the relative capacitance versus field amplitude for various embodiments of stents with a resonant circuit thereon. In this illustration, a solution which provides imageability is a solution that crosses the 24 A/m Applied Field line. The shown total field correction is the calculated (applied + circuit + stent + permeable) fields.

[0229] Figure 40 illustrates magnetic field intensity around current carrying conductor. In the right illustration, the permeable material is symmetrically around conductor. In the left illustration, the permeable material is right of the current carrying conductor. The permeable material keeps the magnetic flux of the induced current in the stent struts confined to the material, thus reducing the canceling effect in the volume of the stent.

[0230] Figures 41 -43 illustrate embodiments of stents capable of being interiorly imaged, non-invasively, using magnetic resonance imaging. In Figure 41 , the circuit's thickness is 20 microns, the insulator's thickness is 170 microns, and the strut's thickness is 50 microns. In Figure 42, the circuit's thickness is 20 microns, the insulator's thickness is 170 microns, and the strut's thickness is 50 microns; however, the circuit is moved from the outer rings because the outer rings carry more current than the other rings. In Figure 43, the nitinol stents are 180 to 220 micron thick. In the insulative standoff example, the stent is 180 microns. The thickness of the silver thickness is 20 microns. The nitinol's resistivity is 9x10^"7 ohm-m, and the silver's resistivity is 15.87x10^"9 ohm-m.

[0231] Figures 44-45 illustrate a mechanical bonding of stent's rings having a disruption of the electrically conductive pathways formed by the stents geometrical structure. In these embodiments, the ends of the rings/struts 9000 of the stents are bonded together using an H-shaped connector 9100 having a dielectric material 9200 therein to provide bonding, elasticity, and electrical insulation. An example of a dielectric material is glass or ceramic. It is noted that, as illustrated in Figure 45, lips or stops 9300 can be included on the H-shaped connector 9100 to prevent the ends of the rings/struts 9000 from disengaging from the H-shaped connector 9100. It is further noted that, as illustrated in Figure 45, stops 9400 can be included on the ends of the rings/struts 9000 to prevent the rings/struts 9000 from disengaging from the H-shaped connector 9100.

[0232] It is noted that the rings/struts connectors of a stent can also be formed of an

H-shaped connector so that adjacent rings/struts are mechanically connected together, but electrically insulated.

[0233] In another embodiment, the stent is mechanically bonded using a zipper strip wherein each rings/strut has a physical shape that mechanically traps the nitinol tube wall in order to minimize dependence on surface bonding.

[0234] Figures 46-48 illustrate stent structures. It is noted that to obtain good performance when stent is parallel to static field, the "rings" of the stent should be designed to be 45 degrees to stent axis, as illustrated in Figure 46. It is further noted that a "jellyroH" resonant wrap may be placed on each ring separately or connect all together.

[0235] As illustrated in Figures 46-48, a circuit is created which is restricted to the struts of a stent to improve lumen imaging. This may also reduce the mutual inductive coupling of the circuit to the inductance of the stent. It is also noted that the location of stent struts connecting stent "zig-zag" rings is an important consideration for the circuit's inductor loops.

[0236] In the various embodiments described above, nanomagnetic coating can be used on the surface of the stent to choke the eddy currents from each stent. Since the nano-iron particles will not touch each other but rather will be in an insulating matrix, mutual inductive coupling can be avoided.

[0237] In the various embodiments described above, a filler material of high electrical impedance, such as another metal or metal alloy, ceramic, or polymer is used to join

(i.e. weld) tube blanks. Moreover, a filler material of high electrical impedance material may be "injected" into the extruded tube, along its long axis, as it is extruded. Also, a high electrical resistance material may be placed between the mechanical tabs to create a region of high resistance that runs the length of the tube. Further, a high electrical resistance filler material may be formed around the partially finished interlocking tab, thereby forming a mechanical joint. Lastly, a high electrical resistance material may be coated on the tube blank prior to forming the stent. Metal is selectively removed in such a way that one or more sections of the high electrical resistance material remains in place and secures together adjacent portions of the stent.

[0238] It is noted that when circuit restricted to conductive stent struts, stent inductance and circuit inductor strongly couple, thereby significantly reducing or eliminating the resonance of the added circuit. [0239] Examples of possible solutions:

Example 1

A material with a relative permeability = 6;

Positioned only on outer surface of stent struts that will carry the circuit traces, between stent and circuit; 170 microns thick;

Resonance saddle circuit over permeable material; and Extremely high field (>80A/m) inside stent model.

Example 2

A material with a relative permeability = 10; Positioned only on inner surface of stent struts; No (resonant) circuit; and 20 μm thick.

[0240] In the bonding discussion above, the dielectric material may be a ceramic or glass. More specifically, a compound of 75% alumina and 24% zirconium; a ceramic containing oxide particles (of aluminum, magnesium and zirconium); a material consisting of zirconium oxide particles added to a matrix of aluminum oxide ceramic, and chromium oxide is added for wear resistance; or oxinium oxidized zirconium can utilized. Also, tantalum-, niobium- and zirconium-based ceramic powders can be utilized.

[0241] It is noted that some or many next-generation stents will be made from a niobium-zirconium alloy. Thus, a zirconium ceramics will provide superior ductility. Moreover, with or without a flash coating of pure zirconium on the outside, zirconium ceramic is a preferred material for insulation and bonding. And if the zirconium ceramic is introduced as a sinterable particulate material with the appropriate binder that outgases when heated, it can be introduced as a 'green' form, crimped, and then sintered. As noted above, the shape factor can be used to guarantee that localized strain rates match the other strut areas, so the physiologic impact is minimized. [0242] It is noted that that any interstitial material (ceramic or otherwise) creates opportunity for stress concentrations and fatigue failure. More specifically, there are stents that contract in length as the stents expand in diameter, due to strut pattern. In some regards, these stents are not utilized due to the effects on the arterial wall. On the other hand, there are other stent designs that compensate for this in the strut design, and so the stents do not change in length as the stents expand.

[0243] Thus, a stent design has a longitudinal strip along its length that is not cut into part of the pattern but is essentially a 'backbone' of appropriate thickness to make it similar in flexure to the remainder of the strut pattern around the circumference. This backbone can be the site of bonding through an electrical insulator. This provides a long and largely undisturbed region, favoring fatigue performance and minimizing localized loading on either adhesive or metal-to-ceramic bonds.

[0244] Figure 49 depicts a stent design 600 comprising conductive stent struts 602 and conductive stent hubs 604 where three or more stent struts meet. It is to be understood that this particular design of the stent 600 is used for illustrative purposes only, whereas the invention herein disclosed is applicable to other stent designs. [0245] Figure 50 depicts a stent assembly 605 illustrating one way that the invention disclosed herein may be implemented. Stent assembly 605 includes non-inductor stent struts 652 and stent hubs 654. Stent assembly 605 further includes an essentially spiral inductor 606 shown as dark lines for illustration purposes only, which is integrated into the stent design.

[0246] The inductor 606 intersects the non-inductor stent struts 652 at the selected stent hubs 662. The hubs 662 are notched to allow the inductor 606 to pass through the notch without direct electrical contact with the stent hub. In one embodiment the inductor 606 passing through the hub notch at locations 662 such that the combined radial thickness of hub plus insulative material plus inductor 606 is essentially the same radial thickness of the stent hubs 654 which do not have notches. [0247] The starting point 607 of the inductor 606 is electrically isolated from direct electrical contact with the stent struts 652. In one embodiment, the inductor starting point 607 is connected to one side of a capacitor. The inductor 606 end point 672 is electrically isolated from direct electrical contact with the stent struts 652. In one embodiment, the inductor end point 672 is connected to one side of a capacitor. In one embodiment, the capacitor that the inductor starting point 607 is connected to is the same capacitor to which the inductor ending point 672 is connected, but at opposite capacitor terminals. In another embodiment, the capacitors are different capacitors. In another embodiment, the inductor is essentially a saddle shaped coil. [0248] Figure 51 depicts a stent assembly 620 including stent struts 622 and stent hubs 624 and further including a circuit having at least an inductor 626. The inductor 626 passes through selected stent struts 628 into which notches have been cut. In one embodiment, the inductor is essentially a spiral shaped inductor. [0249] Figure 50 depicts one way in which the inductor may pass through stent hubs. Figure 52 depicts one way in which the inductor may pass through the stent's struts. [0250] In another embodiment, more than one inductor is integrated into the stent assembly. In one embodiment, one inductor is essentially a spiral shape and another inductor is essentially a saddle shape. In another embodiment, multiple saddle shaped coils are integrated into the stent assembly design. In yet another embodiment, at least two resonant circuits including at least one inductor each is integrated into the stent assembly with each resonant circuit tuned to within 1 MHz of the frequency of a magnetic resonance imaging scanner. In one embodiment, one circuit is tuned to approximately 63.8 MHz and the other circuit is tuned to approximately 127.6 MHz. [0251] In another embodiment, one inductor circuit is tuned to approximately the frequency of a magnetic resonance imaging scanner while the other inductor circuit is tuned to some other frequency and is used for thermally heating the stent and surrounding tissue, after implantation, when a specific non-magnetic resonance imaging frequency is applied to the stent through the biological tissue into which it is implanted. Thermal treatment of tissue as well as magnetic resonance imageability of the stent's lumen is therefore combined. In another embodiment, the thermal treatment may activate the release of therapeutic drugs imbedded in materials attached to at least a portion of the stent assembly. In another embodiment, only one circuit is integrated into the stent assembly and it is used for the thermal treatment previously disclosed. [0252] Figure 52 depicts a portion of a stent assembly 30000 including a stent strut 30020 into which a notch 30080 has been cut. In one embodiment, the notch 30080 has an essentially rectangular cross-sectional shape. In another embodiment, the notch has an essentially curved shape.

[0253] The notch 30080 is lined with one or more materials 30060. In one embodiment, material 30060 is a nonconductive material. In another embodiment, material 30060 includes a non-conductive material as well as an adhesive to bond to inductor segment 30040.

[0254] Inductor segment 30040 is a portion of an inductor's conductor material. In one embodiment, the inductor segment 30040 includes a conductive material. In another embodiment, inductor segment 30040 includes a conductive material covered on at least a portion of the conductive material by an electrically insulative material. In one embodiment, inductor segment 30040 includes tantalum.

[0255] In one embodiment, the notches 30080 in the stent struts and/or hubs are made to the radially outer surface 30100 of the stent. In another embodiment, the notches 30080 are on the radially inner surface 30120 of the stent. In another embodiment, some of the notches in the stent are on the radially outer surface of the stent while other notches are on the radially inner surface of the stent.

[0256] In another embodiment the inductor path about the stent struts is essentially in a helix shape. In another embodiment, the inductor path about the stent struts is essentially a saddle coil shape. In another embodiment the inductor path about the stent struts is essentially a bird cage coil.

[0257] In one embodiment, notch 30080 is deep enough and the inductor segment

30040 and material 30060 is thin enough so that the top of the inductor segment is flush with the surface of stent strut 30020. In another embodiment, the top surface of inductor segment 30040 is approximately flush with the top surface of the stent strut 30020.

[0258] Figure 53 is a top view showing a portion of a stent assembly 35000 comprising a hub region 35100 connecting stent strut segments 35020, 35040, 35060, and 35080. A notch 35120 is cut into the hub region 35100 such that an inductor coil segment can be fastened to the stent assembly 35000. Figure 54 is a side view of the same stent assembly 35000.

[0259] In another embodiment, both the stent strut and the inductor segment have notches which when mated together allows the inductor surfaces to be flush with the stent strut surfaces. In another embodiment, the inductor segment surface is approximately flush with the stent strut surfaces. [0260] Figure 55 depicts a portion of a stent assembly 40000 including a portion of a stent strut 40020 having a radially outer surface 40100 and a radially inner surface 40120. In the embodiment depicted, a notch 40080 is cut into the stent strut 40020 from the radially outer surface 40100. Notch 40080 is cut such that the width of the notch 40080 is wider at the bottom of the notch than at the top of the notch, the top of the notch occurring, in the embodiment depicted at the stent's radially outer surface 40100. A segment of a conductive inductor 40040 is positioned into the notch 40080. An electrically non-conductive material 40060 is positioned between the conductive strut material 40020 and the conductive segment of the inductor 40040. In one embodiment, and as depicted in Figure 55, the segment of the inductor 40040 is shaped to mate with the shape of the notch 40080 in such a way as to prevent the segment of the inductor from moving radially out of the notch 40080.

[0261] Figure 56 depicts one way in which a capacitor can be formed such that the capacitor is integrated into the design of one or more of the stent's struts. In Figure 56, a portion of a stent assembly 50000 is shown including stent struts 50020, 50040. Stent strut 50040 further includes a notch 50100. The notch is partially filled with a dielectric material 50080 and a conductive material 50060 to form the capacitor. The conductive material 50060 forming one plate of a capacitor is not in direct electrical contact with the conductive stent strut 50040. In one embodiment, the inductor coil (not shown) is connected to conductive material 50060. In one embodiment, the notch spans multiple adjacent stent struts and the capacitor formed also spans the multiple adjacent stent struts. In one embodiment the dielectric material 50080 and the conductive capacitor plate 50060 are essentially flush with the surface of the stent strut 50040. [0262] In another embodiment, additional dielectric material is coating over the surface of the conductive material 50060. Additionally, other material may be adding to the stent assembly forming a barrier between the biological material the stent assembly is embedded into and the capacitor plate 50060. Thus, these additional materials and the biological material also form part of the capacitors capacitance. [0263] In one embodiment, the circuit formed is a resonant circuit. In another embodiment, the circuit is a resonant circuit comprising one or more inductive elements and one or more capacitive elements. In another embodiment, the circuit comprises one or more inductive elements one or more capacitive elements and one or more resistive elements. In another embodiment, the circuit comprises one or more inductive elements and two capacitive elements such that the inductive element is essentially a spiral coil around the stent assembly extending from one end of the stent assembly to the other stent assembly connecting to a capacitor at each end of the stent assembly. In one embodiment, there is no return wire. In one embodiment, the resistive element is at least a portion of the material including the conductive inductor element. In one embodiment, the resistive element may be adjusted by constructing the inductor material to have a different cross-sectional area.

[0264] In one embodiment, the circuit is essentially a resonant circuit tuned to the frequency of a magnetic resonance imaging scanner when the stent assembly including the circuit is embedded into a biological body. In another embodiment, the circuit is essentially a resonant circuit tuned to a frequency within 1 kHz of a magnetic resonance imaging when the stent assembly comprising the circuit is embedded into a biological body. In another embodiment, the circuit is essentially a resonant circuit tuned to a frequency within 500 kHz of a magnetic resonance imaging scanner when the stent assembly comprising the circuit is embedded into a biological body. In another embodiment, the circuit is essentially a resonant circuit tuned to a frequency within 1 MHz of a magnetic resonance imaging scanner when the stent assembly comprising the circuit is embedded into a biological body. In another embodiment, the circuit is essentially a resonant circuit tuned to a frequency within 5 MHz of a magnetic resonance imaging scanner when the stent assembly comprising the circuit is embedded into a biological body.

[0265] Figure 57 depicts a modified stent system 70000 including conductive stent struts 70020 and conductive stent hubs 70040. These stent struts 70020 and stent hubs 70040 form conductive stent cells 70060, which are surrounded by stent struts 70020 and stent hubs 70040. Stent system 70000 further includes a non-conductive division 70100 of a set of stent struts and stent hubs from one end 70120 of the stent system 70000 to the other end 70140 of the stent system 70000 such that no conductive stent cell 70060 is merged with another stent cell and no additional conductive stent cell is created.

[0266] The non-conductive division 70100 may be formed by laser (or other) cutting of the stent struts and then reattaching the divided stent struts together with one or more non-conductive materials. (Cutting from a blank cylinder to form the stent would not require cutting existing stent struts. In this case, the stent is initially formed with the division.) In one embodiment, the non-conductive material is applied all along the stent struts and hubs. In another embodiment, the non-conductive material is applied only at the divided stent hubs.

[0267] Other stent patterns (not shown) can likewise be used such that selective stent struts are divided and reattached with a non-conductive material from one end of the stent to the other without adding or diminishing the number of conductive stent cells. [0268] Figure 58 depicts a stent assembly 70500 (similar to stent assembly 70000 depicted in Figure 57) including conductive stent struts 70520, conductive stent hubs 70540, and a non-conductive division 70600. Stent assembly 70500 further includes notches 70720 into which an inductive element 70700 of a circuit (not shown in its entirety) is positioned. Other components of the circuit are not depicted in Figure 58. At least some portions of the inductive element 70700 of the circuit are covered with a non- conductive material to prevent direct electrical contact with the stent struts 70520 at the notches 70720.

[0269] In one embodiment, the inductive element is essentially a saddle shaped coil. In another embodiment, the inductive element is essentially a spiral coil. In one embodiment, one inductive coil element is used in the stent assembly. In another embodiment, more than one inductive coil element is used in the stent assembly. In another embodiment, more than one circuit comprising one or more inductive elements is used in the stent assembly. In one embodiment, the circuit is a resonant circuit. In one embodiment, the resonant circuit is tuned to a frequency within a range of 1 MHz to the operating frequency of a magnetic resonance imaging scanner. [0270] Figure 59 depicts a stent assembly 80500 comprising conductive stent struts 80520 and conducting stent hubs 80540 and further comprising an imbedded inductive element 80600, which is neither in direct electrical contact with stent struts nor in direct electrical contact with stent hubs 80540. Inductive element 80600 is part of an electrical circuit not completely depicted in Figure 59.

[0271] The inductive element is inserted into a selected set of stent struts and stent hubs such that the selected set of stent struts and stent hubs are divided into two parts, the inductive element is positioned between the divided struts and hubs and at least one non-conductive material is interposed between the inductive element and the divided stent struts and hubs. The division of the selected set of stent struts and hubs is such that no conductive stent cell is divided or merged with other cells. That is, no new conductive cells are introduced nor any conductive cell eliminated. [0272] Figure 60 depicts an enlarged view of one portion of a divided stent strut (80620 of Figure 59). Stent strut 80620 is divided into two separate conductive strut parts 80800, 80880 between which conductive inductor element 80840 is positioned. Between the strut part 80800 and the inductor element 80840 is positioned at least one non-conductive material 80820 to prevent direct electrical contact with the stent strut part 80800. Similarly, at least one non-conductive material 80860 is positioned between inductor element 80840 and stent strut part 80880 to prevent direct electrical contact with the stent strut part 80880.

[0273] Figure 61 depicts a stent portion 80900 of the stent assembly 80500 of Figure 59. Stent portion 80900 includes non-divided stent stents 80960, non-divided stent hubs 80980, divided stent struts 80920, divided stent hub 80940, and inserted inductive element 81100. The combined stent struts 80960, 80920 and stent hubs 80980, 80940 form the conductive stent cell 81000.

[0274] Inter-luminal stents are commonly fabricated by selectively removing materials from metallic tubes to form complex geometrical structures that enable the stent to be alternately reduced in diameter for delivery and subsequently expanded to provide therapeutic benefit. Unfortunately, the geometry of the stent, combined with the high electrical conductivity of the metallic materials from which they are produced, serve to create an effective shield against electromagnetic radiation. This shielding effect prevents the interior of the stent to be imaged, non-invasively, using magnetic resonance imaging.

[0275] As noted above, it has been shown that disruption of the electrically conductive pathways formed by the stents geometrical structure, i.e. the "struts" of the stent, can reduce or eliminate the shielding effect. However, creating the desired disruption without compromising the mechanical properties of the stent has proven to be difficult to achieve in practice.

[0276] It is desirable to construct a stent, which is a composite metallic tube that has incorporated into it a section(s) that creates a very level of resistance to the flow of electrical current. Stents are then fabricated from this composite metallic tube in such a way that one or more of the stent struts has within it this region of high electrical resistance. Several embodiments will be discussed below.

[0277] In a first embodiment, metallic tubes are commonly formed by uniformly adding curvature to a flat piece of metal until opposing sides of the metal come into contact with each other, whereby they are welded together using a filler material of the same composition. In this embodiment, the filler material is a dissimilar material of high electrical impedance, such as another metal or metal alloy, ceramic, or polymer. The stent is then fabricated as before. The finished stent then remains mechanically strong while providing a region of high resistance that runs the length of the stent - similar, electrically, to the cut stent shown above.

[0278] In a second embodiment, metallic tubes can also be extrusion formed. In this embodiment, the extrusion process is modified to enable a second material to be injected into the extruded tube, along its long axis, as it is extruded. The result is a region of high resistance that runs the length of the stent.

[0279] In a third embodiment, metallic tubes can also be formed by utilizing interlocking mechanical "tabs" formed into the ends of flat pieces of metal that are uniformly curved until opposing sides of the metal come into contact with and are joined to each other. In this embodiment, a high electrical resistance material is placed between the mechanical tabs to create a region of high resistance that runs the length of the tube and subsequent stent.

[0280] In a fourth embodiment, the stent is partially formed by selectively removing materials from metallic tubes to form a portion of the stents complex geometrical structure. The partially formed stent structure contains metallic portions of partially finished interlocking tabs, and optionally non-functional metal struts that serve to hold together the partially finished interlocking tabs. The partially finished stent is subjected to a second manufacturing step, such as insert molding, to add a high electrical resistance "filler" material (e.g. polymer or metal alloy) around the partially finished interlocking tab, thereby forming a mechanical joint. A third and optional manufacturing step then removes the non-functional metal struts that initially served to hold together the partially finished interlocking tabs. The high electrical resistance filler material then serves as a region(s) of high electrical resistance.

[0281] In another embodiment, a metallic tube is coated on the inside and/or outside surface with a high electrical resistance material. The stent is then fabricated, as before, by selectively removing materials from metallic tubes but in such a way that one or more sections of the high electrical resistance material remains in place and serves to secure together one or more adjacent portions of the stent, thereby forming a region(s) of high electrical resistance.

[0282] The geometry of a stent, combined with the high electrical conductivity of the metallic materials from which they are produced, serve to create an effective shield against electromagnetic radiation. This shielding effect prevents the interior of the stent to be imaged, non-invasively, using magnetic resonance imaging. It has been shown that applying an electrically resonating circuit to the surface of the stent, such as a

"saddle" coil, can enable the interior of the stent to be imaged using magnetic resonance imaging. However, integrating such a coil into the stent is very difficult to achieve in practice.

[0283] It is desirable to construct a stent, which integrates a resonant circuit into the structure of a stent. In a first embodiment, a coil of the resonating circuit is applied to the mechanical struts of the stent. The coil and the coil's return path follow the stent struts.

[0284] In another embodiment, a coil of the resonating circuit is applied, as before, to the mechanical struts of the stent. However, the coil's return path is integrated into a

"seam" running along the long axis of the stent. As used herein, for example, the return path is integrated into the welded joint running along the long axis of the metallic tube from which the stent is fabricated.

[0285] In a further embodiment, a metallic tube from which the stent is fabricated is coated on the inside and/or outside surface(s) by two materials; a high electrical resistance material that electrically insulates from the stent a second electrically conductive material. The stent is then fabricated, as before, by selectively removing materials from metallic tubes but in such a way that leaves the aforementioned coatings intact, which then form the coil and (optionally) capacitive portions of the resonating circuit.

[0286] In summary, a stent sleeve includes an insulative substrate and a conductive trace with a first end and a second end. The conductive trace forms an inductive coil.

The first end of the conductive trace overlaps the second end of the conductive trace with a dielectric material between the first end of the conductive trace and the second end of the conductive trace to form a capacitor. The conductive trace may form multiple inductive coils, wherein the multiple inductive coils may have a common center point.

The multiple inductive coils may be positioned on the insulative substrate to be orthogonal when the stent sleeve is positioned on a stent.

[0287] A stent includes a plurality of struts; a plurality of strut connectors to provide a mechanical connection between adjacent struts; and a conductor having a first end and a second end. The conductor is formed on a set of the plurality of strut connectors and a set of struts to form an electrical loop with a dielectric material between the conductor and the struts and between the conductor and the set of the plurality of strut connectors. The first end of the conductor overlaps the second end of the conductor, the overlapping of the first end of the conductor and the second end of the conductor being located on a strut. The first end of the conductor and the second end of the conductor have a dielectric material therebetween to form a capacitor. The struts may be end struts of the stent; non-end struts of the stent, or two struts of the stent. The electrical loop may form a saddle coil.

[0288] The stent may also include a second conductor having a first end and a second end. The second conductor is formed on a set of the plurality of strut connectors and a set of struts to form a second electrical loop with a dielectric material between the second conductor and the struts and between the conductor and the set of the plurality of strut connectors. The first end of the second conductor overlaps the second end of the second conductor, the overlapping of the first end of the second conductor and the second end of the second conductor being located on a strut. The first end of the second conductor and the second end of the second conductor have a dielectric material therebetween to form a second capacitor.

[0289] A stent includes a plurality of struts; a plurality of strut connectors to provide a mechanical connection between adjacent struts; and a conductor having a first end and a second end. The conductor is formed on a set of the plurality of strut connectors and a set of struts to form an electrical loop with an insulative material between the conductor and the struts and between the conductor and the set of the plurality of strut connectors. The first end of the conductor overlaps the second end of the conductor, the overlapping of the first end of the conductor and the second end of the conductor being located on a strut. The first end of the conductor and the second end of the conductor have a dielectric material therebetween to form a capacitor. The struts may be end struts of the stent; non-end struts of the stent, or two struts of the stent. The electrical loop may form a saddle coil.

[0290] The stent may also include a second conductor having a first end and a second end. The second conductor is formed on a set of the plurality of strut connectors and a set of struts to form a second electrical loop with a dielectric material between the second conductor and the struts and between the conductor and the set of the plurality of strut connectors. The first end of the second conductor overlaps the second end of the second conductor, the overlapping of the first end of the second conductor and the second end of the second conductor being located on a strut. The first end of the second conductor and the second end of the second conductor have a dielectric material therebetween to form a second capacitor.

[0291] A stent includes a plurality of struts, a subset of the plurality of struts having a notched formed therein, and a conductor having a first end and a second end. The conductor is connected to the subset of the plurality of struts at the notches to provide a mechanical connection between the conductor and the subset of the plurality of struts. The conductor is electrical insulated from the subset of the plurality of struts by an insulative material in the notches. The conductor is formed on a portion of struts within the subset of the plurality of struts to form an electrical loop with an insulative material between the conductor and the struts. The first end of the conductor overlaps the second end of the conductor, the overlapping of the first end of the conductor and the second end of the conductor being located on a strut within the subset of the plurality of struts. The first end of the conductor and the second end of the conductor have a dielectric material therebetween to form a capacitor. The struts may be end struts of the stent; non-end struts of the stent, or two struts of the stent. The electrical loop may form a saddle coil. The notches may include an adhesive material to bond the conductor to the strut or may be shaped to mechanically connect the conductor to the strut. The notches may be located on an exterior of the stent or an interior of the stent. The stent may also include a plurality of strut connectors to provide a mechanical connection between adjacent struts.

[0292] The stent may further include a second conductor having a first end and a second end. The second conductor is formed on a set of the plurality of strut connectors and a set of struts to form a second electrical loop with a dielectric material between the second conductor and the struts and between the conductor and the set of the plurality of strut connectors. The first end of the second conductor overlaps the second end of the second conductor, the overlapping of the first end of the second conductor and the second end of the second conductor being located on a strut. The first end of the second conductor and the second end of the second conductor have a dielectric material therebetween to form a second capacitor.

[0293] A stent includes a plurality of struts, each strut having a first end and a second end, and an H-shaped connector having a first channel and a second channel, the first channel having an insulative material therein, the second channel having an insulative material therein. The first end of a strut is connected to the first channel. The second end of a strut being connected to the second channel. [0294] The first channel of the H-shaped connector may include a stop to provide a mechanical connection to the first end of a strut, and the second channel of the H- shaped connector may include a stop to provide a mechanical connection to the second end of a strut. The first channel of the H-shaped connector may include stops to provide a mechanical connection to the first end of a strut, and the second channel of the H- shaped connector may include stops to provide a mechanical connection to the second end of a strut.

[0295] The first end of a strut may include a stop to provide a mechanical connection to the first channel of the H-shaped connector, and the second end of a strut may include a stop to provide a mechanical connection to the second channel of the H- shaped connector. The first end of a strut may include stops to provide a mechanical connection to the first channel of the H-shaped connector, and the second end of a strut may include stops to provide a mechanical connection to the second channel of the H- shaped connector.

[0296] The first channel of the H-shaped connector may include an adhesive material to provide a bond between the first channel of the H-shaped connector and the first end of a strut, and the second channel of the H-shaped connector may include an adhesive material to provide a bond between the second channel of the H-shaped connector and the second end of a strut.

[0297] The stent may also include a plurality of strut connectors to provide a mechanical connection between adjacent struts.

[0298] The stent may further include a subset of the plurality of struts having a notched formed therein, and a conductor having a first end and a second end. The conductor is connected to the subset of the plurality of struts at the notches to provide a mechanical connection between the conductor and the subset of the plurality of struts. The conductor is electrical insulated from the subset of the plurality of struts by an insulative material in the notches. The conductor is formed on a portion of struts within the subset of the plurality of struts to form an electrical loop with an insulative material between the conductor and the struts. The first end of the conductor overlaps the second end of the conductor, the overlapping of the first end of the conductor and the second end of the conductor being located on a strut within the subset of the plurality of struts. The first end of the conductor and the second end of the conductor have a dielectric material therebetween to form a capacitor. [0299] The struts may be end struts of the stent; non-end struts of the stent, or two struts of the stent. The electrical loop may form a saddle coil. The notches may include an adhesive material to bond the conductor to the strut or may be shaped to mechanically connect the conductor to the strut. The notches may be located on an exterior of the stent or an interior of the stent. The stent may also include a plurality of strut connectors to provide a mechanical connection between adjacent struts. [0300] The stent may further include a second conductor having a first end and a second end. The second conductor is formed on a set of the plurality of strut connectors and a set of struts to form a second electrical loop with a dielectric material between the second conductor and the struts and between the conductor and the set of the plurality of strut connectors. The first end of the second conductor overlaps the second end of the second conductor, the overlapping of the first end of the second conductor and the second end of the second conductor being located on a strut. The first end of the second conductor and the second end of the second conductor have a dielectric material therebetween to form a second capacitor.

[0301] A stent includes a plurality of struts, each ring having a first end and a second end, and an H-shaped connector having a first channel and a second channel, the first channel having an insulative material therein, the second channel having an insulative material therein. The first end of each strut is connected to the first channel. The second end of each strut is connected to the second channel.

[0302] The first channel of the H-shaped connector may include a stop to provide a mechanical connection to the first end of each strut, and the second channel of the H- shaped connector may include a stop to provide a mechanical connection to the second end of each strut. The first channel of the H-shaped connector may include stops to provide a mechanical connection to the first end of each strut, and the second channel of the H-shaped connector may include stops to provide a mechanical connection to the second end of each strut.

[0303] The first end of each strut may include a stop to provide a mechanical connection to the first channel of the H-shaped connector, and the second end of each strut may include a stop to provide a mechanical connection to the second channel of the H-shaped connector. The first end of each strut may include stops to provide a mechanical connection to the first channel of the H-shaped connector, and the second end of each strut may include stops to provide a mechanical connection to the second channel of the H-shaped connector. [0304] The first channel of the H-shaped connector may include an adhesive material to provide a bond between the first channel of the H-shaped connector and the first end of each strut, and the second channel of the H-shaped connector may include an adhesive material to provide a bond between the second channel of the H-shaped connector and the second end of each strut.

[0305] The stent may also include a plurality of strut connectors to provide a mechanical connection between adjacent struts.

[0306] The stent may further include a subset of the plurality of struts having a notched formed therein, and a conductor having a first end and a second end. The conductor is connected to the subset of the plurality of struts at the notches to provide a mechanical connection between the conductor and the subset of the plurality of struts. The conductor is electrical insulated from the subset of the plurality of struts by an insulative material in the notches. The conductor is formed on a portion of struts within the subset of the plurality of struts to form an electrical loop with an insulative material between the conductor and the struts. The first end of the conductor overlaps the second end of the conductor, the overlapping of the first end of the conductor and the second end of the conductor being located on a strut within the subset of the plurality of struts. The first end of the conductor and the second end of the conductor have a dielectric material therebetween to form a capacitor.

[0307] The struts may be end struts of the stent; non-end struts of the stent, or two struts of the stent. The electrical loop may form a saddle coil. The notches may include an adhesive material to bond the conductor to the strut or may be shaped to mechanically connect the conductor to the strut. The notches may be located on an exterior of the stent or an interior of the stent. The stent may also include a plurality of strut connectors to provide a mechanical connection between adjacent struts. [0308] The stent may further include a second conductor having a first end and a second end. The second conductor is formed on a set of the plurality of strut connectors and a set of struts to form a second electrical loop with a dielectric material between the second conductor and the struts and between the conductor and the set of the plurality of strut connectors. The first end of the second conductor overlaps the second end of the second conductor, the overlapping of the first end of the second conductor and the second end of the second conductor being located on a strut. The first end of the second conductor and the second end of the second conductor have a dielectric material therebetween to form a second capacitor. [0309] While the present invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and detail may be made herein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

Claims:

1. A stent sleeve, comprising: an insulative substrate; and a conductive trace with a first end and a second end; said conductive trace forming an inductive coil; said first end of said conductive trace overlapping said second end of said conductive trace with a dielectric material between said first end of said conductive trace and said second end of said conductive trace to form a capacitor.

2. The stent sleeve as claimed in claim 1 , wherein said conductive trace forms multiple inductive coils.

3. The stent sleeve as claimed in claim 2, wherein said multiple inductive coils have a common center point.

4. The stent sleeve as claimed in claim 2, wherein said multiple inductive coils are positioned on said insulative substrate to be orthogonal when the stent sleeve is positioned on a stent.

5. A stent, comprising: a plurality of struts; a plurality of strut connectors to provide a mechanical connection between adjacent struts; and a conductor having a first end and a second end; said conductor being formed on a set of said plurality of strut connectors and a set of struts to form an electrical loop with a dielectric material between said conductor and said struts and between said conductor and said set of said plurality of strut connectors; said first end of said conductor overlapping said second end of said conductor, the overlapping of said first end of said conductor and said second end of said conductor being located on a strut; said first end of said conductor and said second end of said conductor having a dielectric material therebetween to form a capacitor.

6. The stent as claimed in claim 5, wherein said struts are end struts of the stent.

7. The stent as claimed in claim 5, wherein said struts are non-end struts of the stent.

8. The stent as claimed in claim 5, wherein said struts are two struts of the stent.

9. The stent as claimed in claim 5, wherein said electrical loop forms a saddle coil.

10. The stent as claimed in claim 5, further comprising: a second conductor having a first end and a second end; said second conductor being formed on a set of said plurality of strut connectors and a set of struts to form a second electrical loop with a dielectric material between said second conductor and said struts and between said conductor and said set of said plurality of strut connectors; said first end of said second conductor overlapping said second end of said second conductor, the overlapping of said first end of said second conductor and said second end of said second conductor being located on a strut; said first end of said second conductor and said second end of said second conductor having a dielectric material therebetween to form a second capacitor.

11. The stent as claimed in claim 10, wherein said struts having said second conductor thereon are end struts of the stent.

12. The stent as claimed in claim 10, wherein said struts having said second conductor thereon are non-end struts of the stent.

13. The stent as claimed in claim 10, wherein said struts having said second conductor thereon are two struts of the stent.

14. The stent as claimed in claim 10, wherein said second electrical loop forms a saddle coil.

15. A stent, comprising: a plurality of struts; a plurality of strut connectors to provide a mechanical connection between adjacent struts; and a conductor having a first end and a second end; said conductor being formed on a set of said plurality of strut connectors and a set of struts to form an electrical loop with an insulative material between said conductor and said struts and between said conductor and said set of said plurality of strut connectors; said first end of said conductor overlapping said second end of said conductor, the overlapping of said first end of said conductor and said second end of said conductor being located on a strut; said first end of said conductor and said second end of said conductor having a dielectric material therebetween to form a capacitor.

16. The stent as claimed in claim 15, wherein said struts are end struts of the stent.

17. The stent as claimed in claim 15, wherein said struts are non-end struts of the stent.

18. The stent as claimed in claim 15, wherein said struts are two struts of the stent.

19. The stent as claimed in claim 15, wherein said electrical loop forms a saddle coil.

20. The stent as claimed in claim 15, further comprising: a second conductor having a first end and a second end; said second conductor being formed on a set of said plurality of strut connectors and a set of struts to form a second electrical loop with an insulative material between said second conductor and said struts and between said conductor and said set of said plurality of strut connectors; said first end of said second conductor overlapping said second end of said second conductor, the overlapping of said first end of said second conductor and said second end of said second conductor being located on a strut; said first end of said second conductor and said second end of said second conductor having a dielectric material therebetween to form a second capacitor.

21. The stent as claimed in claim 20, wherein said struts having said second conductor thereon are end struts of the stent.

22. The stent as claimed in claim 20, wherein said struts having said second conductor thereon are non-end struts of the stent.

23. The stent as claimed in claim 20, wherein said struts having said second conductor thereon are two struts of the stent.

24. The stent as claimed in claim 20, wherein said second electrical loop forms a saddle coil.

25. A stent, comprising: a plurality of struts, a subset of said plurality of struts having a notched formed therein; and a conductor having a first end and a second end; said conductor being connected to said subset of said plurality of struts at said notches to provide a mechanical connection between said conductor and said subset of said plurality of struts; said conductor being electrical insulated from said subset of said plurality of struts by an insulative material in said notches; said conductor being formed on a portion of struts within said subset of said plurality of struts to form an electrical loop with an insulative material between said conductor and said struts; said first end of said conductor overlapping said second end of said conductor, the overlapping of said first end of said conductor and said second end of said conductor being located on a strut within said subset of said plurality of struts; said first end of said conductor and said second end of said conductor having a dielectric material therebetween to form a capacitor.

26. The stent as claimed in claim 25, wherein said portion of struts are portions of end struts of the stent.

27. The stent as claimed in claim 25, wherein said portion of struts are portions of non-end struts of the stent.

28. The stent as claimed in claim 25, wherein said portion of struts are portions of two struts of the stent.

29. The stent as claimed in claim 25, wherein said electrical loop forms a saddle coil.

30. The stent as claimed in claim 25, wherein said notches include an adhesive material to bond said conductor to said strut.

31. The stent as claimed in claim 25, wherein said notches is shaped to mechanically connect said conductor to said strut.

32. The stent as claimed in claim 25, wherein said notches are located on an exterior of the stent.

33. The stent as claimed in claim 25, wherein said notches are located on an interior of the stent.

34. The stent as claimed in claim 25, further comprising: a plurality of strut connectors to provide a mechanical connection between adjacent struts.

35. The stent as claimed in claim 25, further comprising: a second conductor having a first end and a second end; said second conductor being connected to said subset of said plurality of struts at said notches to provide a mechanical connection between said second conductor and said subset of said plurality of struts; said second conductor being electrical insulated from said subset of said plurality of struts by an insulative material in said notches; said second conductor being formed on a portion of struts within said subset of said plurality of struts to form an electrical loop with an insulative material between said second conductor and said struts; said first end of said second conductor overlapping said second end of said second conductor, the overlapping of said first end of said second conductor and said second end of said second conductor being located on a strut within said subset of said plurality of struts; said first end of said second conductor and said second end of said second conductor having a dielectric material therebetween to form a capacitor.

36. The stent as claimed in claim 35, wherein said struts having said second conductor thereon are end struts of the stent.

37. The stent as claimed in claim 35, wherein said struts having said second conductor thereon are non-end struts of the stent.

38. The stent as claimed in claim 35, wherein said struts having said second conductor thereon are two struts of the stent.

39. The stent as claimed in claim 35, wherein said second electrical loop forms a saddle coil.

40. A stent, comprising: a plurality of struts, each strut having a first end and a second end; and an H-shaped connector having a first channel and a second channel, said first channel having an insulative material therein, said second channel having an insulative material therein; said first end of a strut being connected to said first channel; said second end of a strut being connected to said second channel.

41. The stent as claimed in claim 40, wherein said first channel of said H-shaped connector includes a stop to provide a mechanical connection to said first end of a strut.

42. The stent as claimed in claim 41 , wherein said second channel of said H- shaped connector includes a stop to provide a mechanical connection to said second end of a strut.

43. The stent as claimed in claim 40, wherein said first channel of said H-shaped connector includes stops to provide a mechanical connection to said first end of a strut.

44. The stent as claimed in claim 43, wherein said second channel of said H- shaped connector includes stops to provide a mechanical connection to said second end of a strut.

45. The stent as claimed in claim 40, wherein said first end of a strut includes a stop to provide a mechanical connection to said first channel of said H-shaped connector.

46. The stent as claimed in claim 45, wherein said second end of a strut includes a stop to provide a mechanical connection to said second channel of said H-shaped connector.

47. The stent as claimed in claim 40, wherein said first end of a strut includes stops to provide a mechanical connection to said first channel of said H-shaped connector.

48. The stent as claimed in claim 47, wherein said second end of a strut includes stops to provide a mechanical connection to said second channel of said H-shaped connector.

49. The stent as claimed in claim 40, wherein said first channel of said H-shaped connector includes an adhesive material to provide a bond between said first channel of said H-shaped connector and said first end of a strut.

50. The stent as claimed in claim 49, wherein said second channel of said H- shaped connector includes an adhesive material to provide a bond between said second channel of said H-shaped connector and said second end of a strut.

51. The stent as claimed in claim 40, further comprising: a plurality of strut connectors to provide a mechanical connection between adjacent struts.

52. The stent as claimed in claim 40, further comprising: a subset of said plurality of struts having a notched formed therein; and a conductor having a first end and a second end; said conductor being connected to said subset of said plurality of struts at said notches to provide a mechanical connection between said conductor and said subset of said plurality of struts; said conductor being electrical insulated from said subset of said plurality of struts by an insulative material in said notches; said conductor being formed on a portion of struts within said subset of said plurality of struts to form an electrical loop with an insulative material between said conductor and said struts; said first end of said conductor overlapping said second end of said conductor, the overlapping of said first end of said conductor and said second end of said conductor being located on a strut within said subset of said plurality of struts; said first end of said conductor and said second end of said conductor having a dielectric material therebetween to form a capacitor.

53. The stent as claimed in claim 52, wherein said portion of struts are portions of end struts of the stent.

54. The stent as claimed in claim 52, wherein said portion of struts are portions of non-end struts of the stent.

55. The stent as claimed in claim 52, wherein said portion of struts are portions of two struts of the stent.

56. The stent as claimed in claim 52, wherein said electrical loop forms a saddle coil.

57. The stent as claimed in claim 52, wherein said notches include an adhesive material to bond said conductor to said strut.

58. The stent as claimed in claim 52, wherein said notches is shaped to mechanically connect said conductor to said strut.

59. The stent as claimed in claim 52, wherein said notches are located on an exterior of the stent.

60. The stent as claimed in claim 52, wherein said notches are located on an interior of the stent.

61. The stent as claimed in claim 52, further comprising: a second conductor having a first end and a second end; said second conductor being connected to said subset of said plurality of struts at said notches to provide a mechanical connection between said second conductor and said subset of said plurality of struts; said second conductor being electrical insulated from said subset of said plurality of struts by an insulative material in said notches; said second conductor being formed on a portion of struts within said subset of said plurality of struts to form an electrical loop with an insulative material between said second conductor and said struts; said first end of said second conductor overlapping said second end of said second conductor, the overlapping of said first end of said second conductor and said second end of said second conductor being located on a strut within said subset of said plurality of struts; said first end of said second conductor and said second end of said second conductor having a dielectric material therebetween to form a capacitor.

62. The stent as claimed in claim 61 , wherein said struts having said second conductor thereon are end struts of the stent.

63. The stent as claimed in claim 61 , wherein said struts having said second conductor thereon are non-end struts of the stent.

64. The stent as claimed in claim 61 , wherein said struts having said second conductor thereon are two struts of the stent.

65. The stent as claimed in claim 61 , wherein said second electrical loop forms a saddle coil.

66. A stent, comprising: a plurality of struts, each ring having a first end and a second end; and an H-shaped connector having a first channel and a second channel, said first channel having an insulative material therein, said second channel having an insulative material therein; said first end of each strut being connected to said first channel; said second end of each strut being connected to said second channel.

67. The stent as claimed in claim 66, wherein said first channel of said H-shaped connector includes a stop to provide a mechanical connection to said first end of each strut.

68. The stent as claimed in claim 67, wherein said second channel of said H- shaped connector includes a stop to provide a mechanical connection to said second end of each strut.

69. The stent as claimed in claim 66, wherein said first channel of said H-shaped connector includes stops to provide a mechanical connection to said first end of each strut.

70. The stent as claimed in claim 69, wherein said second channel of said H- shaped connector includes stops to provide a mechanical connection to said second end of each strut.

71. The stent as claimed in claim 66, wherein said first end of each strut includes a stop to provide a mechanical connection to said first channel of said H-shaped connector.

72. The stent as claimed in claim 71 , wherein said second end of each strut includes a stop to provide a mechanical connection to said second channel of said H- shaped connector.

73. The stent as claimed in claim 66, wherein said first end of each strut includes stops to provide a mechanical connection to said first channel of said H-shaped connector.

74. The stent as claimed in claim 73, wherein said second end of each strut includes stops to provide a mechanical connection to said second channel of said H- shaped connector.

75. The stent as claimed in claim 66, wherein said first channel of said H-shaped connector includes an adhesive material to provide a bond between said first channel of said H-shaped connector and said first end of each strut.

76. The stent as claimed in claim 75, wherein said second channel of said H- shaped connector includes an adhesive material to provide a bond between said second channel of said H-shaped connector and said second end of each strut.

77. The stent as claimed in claim 66, further comprising: a plurality of strut connectors to provide a mechanical connection between adjacent rings.

78. The stent as claimed in claim 66, further comprising: a subset of said plurality of struts having a notched formed therein; and a conductor having a first end and a second end; said conductor being connected to said subset of said plurality of struts at said notches to provide a mechanical connection between said conductor and said subset of said plurality of struts; said conductor being electrical insulated from said subset of said plurality of struts by an insulative material in said notches; said conductor being formed on a portion of struts within said subset of said plurality of struts to form an electrical loop with an insulative material between said conductor and said struts; said first end of said conductor overlapping said second end of said conductor, the overlapping of said first end of said conductor and said second end of said conductor being located on a strut within said subset of said plurality of struts; said first end of said conductor and said second end of said conductor having a dielectric material therebetween to form a capacitor.

79. The stent as claimed in claim 78, wherein said portion of struts are portions of end struts of the stent.

80. The stent as claimed in claim 78, wherein said portion of struts are portions of non-end struts of the stent.

81. The stent as claimed in claim 78, wherein said portion of struts are portions of two struts of the stent.

82. The stent as claimed in claim 78, wherein said electrical loop forms a saddle coil.

83. The stent as claimed in claim 78, wherein said notches include an adhesive material to bond said conductor to said strut.

84. The stent as claimed in claim 78, wherein said notches is shaped to mechanically connect said conductor to said strut.

85. The stent as claimed in claim 78, wherein said notches are located on an exterior of the stent.

86. The stent as claimed in claim 78, wherein said notches are located on an interior of the stent.

87. The stent as claimed in claim 78, further comprising: a second conductor having a first end and a second end; said second conductor being connected to said subset of said plurality of struts at said notches to provide a mechanical connection between said second conductor and said subset of said plurality of struts; said second conductor being electrical insulated from said subset of said plurality of struts by an insulative material in said notches; said second conductor being formed on a portion of struts within said subset of said plurality of struts to form an electrical loop with an insulative material between said second conductor and said struts; said first end of said second conductor overlapping said second end of said second conductor, the overlapping of said first end of said second conductor and said second end of said second conductor being located on a strut within said subset of said plurality of struts; said first end of said second conductor and said second end of said second conductor having a dielectric material therebetween to form a capacitor.

88. The stent as claimed in claim 87, wherein said struts having said second conductor thereon are end struts of the stent.

89. The stent as claimed in claim 87, wherein said struts having said second conductor thereon are non-end struts of the stent.

90. The stent as claimed in claim 87, wherein said struts having said second conductor thereon are two struts of the stent.

91. The stent as claimed in claim 87, wherein said second electrical loop forms a saddle coil.