Medical equipment for interventional MRI

Abstract

The present disclosure relates to medical devices, methods for performing interventional procedures under MRI guidance, and methods for manufacturing medical devices. An exemplary medical device includes an elongate member, a reinforcing member, and a marker. The elongate member has a proximal end, a distal end, and a circumferential wall having an outer surface and an inner surface defining a lumen. The reinforcing member is disposed within the circumferential wall and extends along the length of the elongate member, the reinforcing member being formed from a first material and having a first susceptibility. The marker is attached to the elongate member, the marker being formed from a second material and having a second susceptibility different from the first susceptibility.

Description

[Technical field]

[0001] The present disclosure relates generally to the field of medical devices. More particularly, the present disclosure relates to interventional medical devices useful in performing interventions under magnetic resonance imaging (MRI), methods for performing interventional procedures under MRI, and methods for manufacturing medical devices. A particular example described herein relates to an introducer sheath. [Background technology]

[0002] MRI-guided interventional procedures offer several advantages over X-ray guided interventions: for example, patients are not exposed to ionizing radiation, and MRI allows for characterization of tissue and fluid flow during the interventional procedure. For at least these reasons, the use of interventional MRI is becoming more widely accepted, and the number of procedures that can be performed under MRI is increasing overall.

[0003] However, current technology only limits the number of interventional medical devices suitable for use under MRI, which continues to limit the increased use of interventional MRI procedures. As a result, patients have yet to fully benefit from interventional MRI technology and, in fact, often have less convenient and perhaps less effective options for certain treatments.

[0004] For example, without interventional MRI, the clinical pathway from initial examination to treatment requires the use of multiple imaging modalities to address some diseases. At a practical level, this use of multiple imaging modalities may require multiple visits to the clinic. The traditional approach to treating prostate cancer is a good example, where visualization, biopsy, and treatment are performed over three separate visits to the clinic. During the first visit, a scan is performed using a magnetic resonance scanner to generate images of the prostate and any abnormalities. The patient then leaves the clinic for review of the images. If abnormalities are found, the patient returns to the clinic to complete a biopsy of the abnormal tissue sample. Software combines the magnetic resonance images with the procedural ultrasound to provide guidance for performing the biopsy. This fusion reduces the value of the diagnostic magnetic resonance images. The patient then leaves the clinic again, waiting for the biopsy specimen to be reviewed to determine whether further treatment is needed (e.g., if the review is positive for a prostate cancer diagnosis). If further treatment is needed, the patient must return for a third visit to receive the treatment. These three patient visits often take months to complete, resulting in patients not receiving prompt treatment and increasing the overall cost of treatment for both the patient and the healthcare providers involved. Furthermore, using software to combine images from multiple imaging modalities, such as magnetic resonance images and ultrasound images, is fraught with deficiencies such as image overlay and / or alignment issues and tissue compression displacement. Ultimately, these shortcomings of current treatment modalities can limit the overall effectiveness of treatment. Interventional MRI has the potential to overcome these shortcomings. Summary of the Invention [Problem to be solved by the invention]

[0005] Thus, there is a need for new and improved interventional medical devices useful in the administration of MRI-guided procedures, methods for administering MRI-guided interventional procedures, and methods for manufacturing the medical devices. [Means for solving the problem]

[0006] A brief overview of selected examples Described herein are various examples of interventional medical devices useful in the administration of MRI-guided procedures, methods of administering MRI-guided interventional procedures, and methods of manufacturing the medical devices.

[0007] An exemplary medical device includes an elongate member having a proximal end, a distal end, and a circumferential wall having an outer surface and an inner surface defining a lumen, a reinforcing member disposed within the circumferential wall extending along the length of the elongate member and formed from a first material and having a first susceptibility, and a marker attached to the elongate member and formed from a second material and having a second susceptibility different from the first susceptibility.

[0008] Another example medical device includes an elongate member having a proximal end, a distal end, and a circumferential wall having an outer surface and an inner surface defining a lumen, a reinforcing member disposed within the circumferential wall extending along the length of the elongate member and formed from a first material having a first susceptibility, and a marker disposed within the circumferential wall distal to the reinforcing member and formed from a second material having a second susceptibility different from the first material and greater than the first susceptibility.

[0009] Another exemplary medical device includes an elongate member having a proximal end, a distal end, and a circumferential wall having an outer surface and an inner surface defining a lumen, a reinforcing member extending along the length of the elongate member and formed from a first material having a first susceptibility, the reinforcing member including a coil disposed within the circumferential wall, and a marker disposed within the circumferential wall distal to the reinforcing member and formed from a second material having a second susceptibility different from the first material and greater than the first susceptibility.

[0010] Another example medical device includes an elongate member having a proximal end, a distal end, and a circumferential wall having an outer surface and an inner surface defining a lumen, a reinforcing member disposed within the circumferential wall and extending along the length of the elongate member and formed from a first material having a first magnetic susceptibility, and a marker attached to the elongate member and formed from a second material having a second magnetic susceptibility greater than the first magnetic susceptibility.

[0011] Another example medical device includes an elongate member having a proximal end, a distal end, and a circumferential wall having an outer surface and an inner surface defining a lumen, a reinforcing member disposed within the circumferential wall extending along the length of the elongate member and formed from a first material having a first magnetic susceptibility, and a marker disposed within the circumferential wall distal to the reinforcing member and formed from a second material having a second magnetic susceptibility different from the first material and greater than the first magnetic susceptibility.

[0012] Another example medical device includes an elongate member having a proximal end, a distal end, and a circumferential wall having an outer surface and an inner surface defining a lumen; a reinforcing member extending along the length of the elongate member and formed from a first material having a first magnetic susceptibility, the reinforcing member including a coil disposed within the circumferential wall; and a marker disposed within the circumferential wall distal to the reinforcing member and formed from a second material having a second magnetic susceptibility different from the first material and greater than the first magnetic susceptibility.

[0013] Another example medical device includes an elongate member having a proximal end, a distal end, and a circumferential wall having an outer surface and an inner surface defining a lumen, a reinforcing member extending along the length of the elongate member and formed from a first material having a first magnetic susceptibility, the reinforcing member including a mesh disposed within the circumferential wall, and a marker disposed within the circumferential wall distal to the reinforcing member and formed from a second material having a second magnetic susceptibility different from the first material and greater than the first magnetic susceptibility.

[0014] Also included are various exemplary methods for performing MRI-guided interventional procedures.

[0015] Various exemplary methods of manufacturing a medical device are described.

[0016] These and other exemplary interventional medical devices, methods of performing interventional treatments under MRI, and methods of manufacturing medical devices can be further understood by reviewing the detailed description of selected examples, below, and in the referenced drawings. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a side view of an exemplary medical device. [Diagram 2] FIG. 2 is an enlarged cross-sectional view of the medical device shown in FIG. [Figure 2A] FIG. 13 is an enlarged cross-sectional view of an alternative medical device. [Diagram 3] 2 is an enlarged cross-sectional view of the distal end of the medical device shown in FIG. 1. [Figure 4] 2 is a cross-sectional view of the tubular medical device shown in FIG. 1 taken along line AA. [Diagram 5] 2 is a cross-sectional view of the tubular medical device shown in FIG. 1 taken along line BB. [Figure 6] 2 is a cross-sectional view of the tubular medical device shown in FIG. 1 taken along line CC. [Figure 7] 2 is a cross-sectional view of the tubular medical device shown in FIG. 1 taken along line DD. [Figure 8] FIG. 1 is a side view of an exemplary introducer sheath. [Figure 9] FIG. 13 is a side view of another exemplary medical device, including a close-up view of a distal portion of the medical device. [Figure 10] 1 is a magnetic resonance image of a medical device of the prior art and a medical device according to an embodiment. [Figure 11] 1 is a magnetic resonance image of a medical device of the prior art and a medical device according to an embodiment. [Figure 12] 1 is a magnetic resonance image of a medical device of the prior art and a medical device according to an embodiment. [Figure 13] 1 is a magnetic resonance image of a medical device of the prior art and a medical device according to an embodiment. [Figure 14]1 is a magnetic resonance image of three medical devices according to an embodiment. [Figure 15] FIG. 1 is a flow chart diagram of an exemplary method for administering an interventional treatment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] A brief detailed description of selected examples The following detailed description and accompanying drawings describe and illustrate various exemplary interventional medical devices, imaging methods, methods of performing interventional treatment under MRI, and methods of manufacturing medical devices. The descriptions and illustrations of these examples are provided to enable those skilled in the art to make and use the interventional medical devices, and to perform the imaging methods, methods of performing interventional treatment under MRI, and methods of manufacturing interventional medical devices. They are not intended to limit the scope of the invention or its protection in any way. The invention can be practiced or performed in various ways, and the examples described and illustrated herein are not considered to be exhaustive.

[0019] As used herein, the term "attached" refers to one member being secured to another member such that the members do not completely separate from one another during use, which is in accordance with the intended use of the product that contains the members in their attached form.

[0020] As used herein, the term "circumference" refers to the outer surrounding boundary of a body, element, or feature and does not impart any structural organization to the body, element, or feature.

[0021] As used herein, the term "magnetic susceptibility" refers to the intrinsic property of a material relating to how magnetized it is in an applied magnetic field.

[0022] As used herein, the term "marker" refers to a discrete deposit of a first material on a second material such that the first material is visible under MRI and distinguishable from the second material under MRI, a portion of an interventional device where a first material is incorporated into a second material such that the combination of the first and second materials is visible under MRI and distinguishable from the second material under MRI, and a portion of an interventional device where a material forming a part of the interventional device is manipulated such that it is visible under MRI and distinguishable from the rest of the interventional device under MRI.

[0023] As used herein, the term "passive" with respect to a marker refers to a marker that is not energized or is energized only by the electromagnetic field of a magnetic resonance scanner.

[0024] As used herein, the term "susceptibility," when not immediately followed by "magnetic," refers to the ability of an element to be influenced by an external magnetic field. Susceptibility depends on various characteristics of the element, including its size, density, geometric configuration, volume, and other physical properties, as well as the magnetic susceptibility of the material from which the element is formed.

[0025] As used herein, the term "treatment" refers to a medical procedure performed on or in a part of a patient's body. Examples of treatments include the delivery of a drug to a site within a blood vessel, the modulation of the local environment of a blood vessel, such as by heating or cooling, and the removal of tissue or a portion of tissue from a site within a patient's body (i.e., a biopsy).

[0026] As used herein, the term "wire" refers to a strand or rod of material. The term does not require any particular cross-sectional shape, composition, physical properties, or method of manufacture by which the referenced element is made.

[0027] 1, 2, 3, 4, 5, 6, and 7 illustrate an exemplary medical device 100. The medical device 100 includes an elongate member 110 having a proximal end 112, a distal end 114, a longitudinal axis 102 extending between the proximal end 112 and the distal end 114, and a length 104 extending from the proximal end 112 to the distal end 114. The elongate member 110 has a peripheral wall 116 having an outer surface 118 and an inner surface 120 defining a lumen 122. The lumen 122 extends from a proximal opening 124 on the proximal end 112 to a distal opening 126 on the distal end 114. A reinforcing member 128 is disposed within the peripheral wall 116 and extends along the length 106 of the elongate member 110. The reinforcing member 128 is formed from a first material having a first susceptibility. The marker 130 is attached to the elongate member 110 and is formed from a second material having a second susceptibility different from the first susceptibility. The first and second materials may be the same or different. Thus, the first and second materials may have the same or different magnetic susceptibilities.

[0028] The elongate member 110 is formed from a polymeric material that allows the reinforcing member 128 to be disposed within the peripheral wall 116 during manufacture. Any polymeric material may be used, and one of skill in the art would be able to select a suitable polymeric material for the elongate member in a medical device according to a particular embodiment based on a variety of considerations, including any desired handling and performance characteristics of the medical device, such as torqueability and pushability. Examples of suitable polymeric materials include, but are not limited to, thermoformable polymeric materials, such as polyamide materials. These polymeric materials are believed to be desirable at least due to their ability to melt and flow between and around elements during a thermoforming or heat shrinking process. Nylon is believed to be particularly advantageous at least due to its ready availability and well-characterized properties.

[0029] The elongate member 110 can have any suitable configuration, and one of skill in the art will be able to select a suitable configuration for a particular embodiment of the medical device based on several considerations, including the application of the medical device and the nature of any blood vessel in which the medical device is intended to be placed. In the example shown, the elongate member 110 includes a distal portion 132 that defines a taper 134 along the outer surface 118 such that the distal opening 126 has the same diameter as the proximal opening 124. For example, the thickness of the circumferential wall 116 can be gradually reduced over the distal portion 132, while the inner diameter of the lumen 122 is continuous over the distal portion 132. Alternatively, the elongate member 110 can include a distal portion 132 that defines a taper 134 along both the outer surface 118 and the inner surface 120 such that the distal opening 126 has a diameter smaller than the diameter of the proximal opening 124. Also alternatively, the elongate member 110 can have substantially continuous outer and inner diameters along its length.

[0030] The elongate member can have any suitable axial length, and one of skill in the art would be able to select a suitable length for a particular embodiment of a medical device based on a variety of considerations, including the intended use of the medical device and the nature of any vessel in which the medical device is intended to be placed. Examples of lengths that may be suitable for elongate members in medical devices according to the present invention include, but are not limited to, equal to, greater than, less than, or about 100 centimeters, 110 centimeters, 120 centimeters, 130 centimeters, 140 centimeters, 240 centimeters, 250 centimeters, 260 centimeters, 270 centimeters, 280 centimeters, between about 50 centimeters and about 350 centimeters, between about 100 centimeters and about 280 centimeters, between about 120 centimeters and about 260 centimeters, and any other lengths that may be suitable for a particular embodiment of a medical device.

[0031] 2 and 4, the reinforcing member 128 is embedded within the thickness of the peripheral wall 116 of the elongate member 110 such that the reinforcing member 128 is disposed completely within the thickness of the elongate member 110 and such that no portion of the reinforcing member 128 breaches any portion of either the exterior surface 118 or the interior surface 120 of the elongate member 110. The reinforcing member 128 extends along the axial length 106 of the elongate member 110, around the lumen 122. The reinforcing member 128 is formed from a metal or alloy having a first susceptibility, the magnetic susceptibility being less than that of the marker 130.

[0032] The reinforcing member 128 can have any suitable structural configuration for the elongate member 110 that provides a desired extension along the axial length 106 of the elongate member 110 around the lumen 122. One of skill in the art will be able to select a desired structural configuration for the reinforcing member in a particular embodiment of a medical device based on various considerations, including any desired handling characteristics of the medical device. In the embodiment shown, the reinforcing member 110 comprises a wire 135 formed into a coil 138 having a thickness 136 and extending along the axial length 106 of the elongate member 110 around the lumen 122. Adjacent turns of the coil 138 are separated by gaps 140. However, the reinforcing member of a medical device according to certain embodiments can have other alternative structural configurations. For example, the reinforcing member can be formed into an interrupted coil, a coil with a variable pitch along its axial length, a coil with a variable diameter along its axial length, and combinations of these structural configurations. 2A illustrates an alternative elongate member 110' in which the reinforcing member 128' comprises a mesh 138' of wire members 135'. Similar to the embodiment illustrated in FIG. 2, the reinforcing member 128' is embedded within the thickness of the peripheral wall 116' such that the reinforcing member 128' is disposed entirely within the thickness of the elongate member 110', and no portion of the mesh 138' protrudes from the outer surface 118' or the inner surface 120' of the elongate member 110'. Also similar to the embodiment illustrated in FIG. 2, the reinforcing member 128' extends around the lumen 122' of the elongate member 110'. Other examples of suitable structural configurations for the reinforcing member include, but are not limited to, a secondary structure forming a plurality of cells, such as hexagonal or octagonal shaped cells, or the reinforcing member comprises a braided material that extends (e.g., partially, completely) around the lumen of the elongate member and is embedded (e.g., completely) within the thickness of the peripheral wall of the elongate member.

[0033] The reinforcing member 128 has a susceptibility different from that of the marker 130. Thus, the reinforcing member 128 can be formed from any metal, alloy, or other material that provides a desired relative susceptibility compared to the susceptibility of the marker 130. One skilled in the art will be able to select suitable materials for the reinforcing members in medical devices according to certain embodiments based on various considerations, including the composition of the markers in the medical device. Suitable combinations of materials, properties, and structural configurations for the reinforcing members and markers of medical devices according to the present invention are described in detail below. Examples of suitable materials for the reinforcing members include, but are not limited to, titanium, alloys, such as alloys containing 1% or less by weight of iron, such as cobalt chromium alloys, polymeric materials such as polyether ether ketone (PEEK), and other materials.

[0034] The reinforcing member 128 can extend along any axial length of the elongate member 110, and one of ordinary skill in the art would be able to select a suitable axial length for a particular embodiment of the medical device based on various considerations, including any desired handling characteristics of the medical device. As best shown in FIG. 1 , the reinforcing member 128 of the exemplary medical device 100 extends along an axial length 106 that is less than the overall axial length 104 of the elongate member 110. The proximal portion 142 of the elongate member 110 includes the proximal end 112 and is devoid of the reinforcing member 128. That is, the reinforcing member 128 terminates and does not extend to the proximal portion 142 of the elongate member 110. Similarly, the distal portion 132 of the elongate member 110 includes the distal end 114 and is devoid of the reinforcing member 128. Thus, the reinforcing member 128 terminates and does not extend to the distal portion 132 of the elongate member 110. It may be advantageous to axially separate the markers 130 from the distal end of the stiffening member 128. This axial separation of these elements provides desirable imaging characteristics in terms of the relative susceptibility of the materials forming these elements, and further provides desirable stiffness at the distal end relative to the portion of the elongate member that includes the stiffening member, without sacrificing the advantageous handling characteristics imparted to the other portions of the elongate member that include the stiffening member. Thus, as best shown in FIG. 1, the distal portion 132 of the elongate member 110 is free of the stiffening member 128. However, alternatively, the markers may be formed as part of the stiffening member (e.g., attached to, formed from the same material) such that the material forming the marker, or a portion of the material forming the marker, has a different susceptibility than the susceptibility of the material forming the remainder of the stiffening member, as described herein.

[0035] Examples of suitable axial lengths for the reinforcing member of a medical device according to certain embodiments include, but are not limited to, 100% of the axial length of the elongated member of the medical device, about 100% of the axial length of the elongated member of the medical device, less than 100% of the axial length of the elongated member of the medical device, about 95% of the axial length of the elongated member of the medical device, about 90% of the axial length of the elongated member of the medical device, about 85% of the axial length of the elongated member of the medical device, and about 80% of the axial length of the elongated member of the medical device. Other examples of suitable axial lengths for the reinforcing member of a medical device according to certain embodiments include, but are not limited to, about 50% to about 100% of the axial length of the elongated member of the medical device, about 60% to about 95% of the axial length of the elongated member of the medical device, about 70% to about 95% of the axial length of the elongated member of the medical device, about 80% to about 95% of the axial length of the elongated member of the medical device, and about 90% to about 95% of the axial length of the elongated member of the medical device.

[0036] 1 and 6, the marker 130 is embedded within the thickness of the peripheral wall 116 of the elongate member 110 such that the marker 130 is disposed completely within the thickness of the elongate member 110 and such that no portion of the marker 130 breaches any portion of either the exterior surface 118 or the interior surface 120 of the elongate member 110. In the illustrated embodiment, the marker 130 extends around the lumen 122 of the elongate member 110. The marker 130 is a passive marker, formed from a metal or metal alloy, and has a susceptibility different from that of the stiffening member 128.

[0037] The markers 130 may have any structural configuration, and one of skill in the art would be able to select a suitable structural configuration for a medical device according to a particular embodiment based on various considerations, including any desired visualization characteristics when the medical device is used with an imaging modality such as MRI. Examples of suitable configurations include, but are not limited to, rings, strips, plugs, torsion bands, torsion rings, multiple bands attached to each other, multiple rings attached to each other, and other configurations. A circumferential band of material as shown in Figures 1 and 6 is believed to be particularly advantageous. Also, a medical device may include any number of markers, and one of skill in the art would be able to select a suitable number of markers for a medical device according to a particular embodiment based on various considerations, including any desired visualization pattern when the medical device is used with an imaging modality such as MRI. Examples of suitable numbers include, but are not limited to, 1, more than 1, 2, multiple, 3, more than 3, 4, 5, 6, 7, 8, 9, 10, and more than 10.

[0038] The marker 130 may be disposed at any suitable location relative to the reinforcing member 128, and one of skill in the art would be able to select a suitable location for the marker relative to the reinforcing member in a particular embodiment of a medical device based on various considerations, including any desired visualization pattern when the medical device is used with an imaging modality such as MRI. As best shown in FIG. 1 , the marker 130 of the exemplary medical device 100 is positioned distal to the reinforcing member 128, at a distal portion 132 of the elongate member 110. Other examples of suitable locations include, but are not limited to, within the shaft of the elongate member that includes the reinforcing member such that the marker overlaps the reinforcing member, within the shaft of the elongate member proximal to the reinforcing member, at the distal end of the elongate member, the proximal end of the elongate member, and combinations of these locations with multiple markers.

[0039] The marker 130 has a magnetic susceptibility that is different from that of the reinforcing member 128. Thus, the marker may be formed from any metal, alloy, or other material that provides a desired relative susceptibility compared to the susceptibility of the reinforcing member 128. One skilled in the art will be able to select suitable materials for the markers in a medical device according to a particular embodiment based on a variety of considerations, including the composition of the reinforcing members in the medical device. Suitable combinations of materials for the reinforcing members and markers of medical devices according to the present invention are described in detail below. Examples of suitable materials for the marker include, but are not limited to, metals such as titanium, nickel, and other metals, alloys such as stainless alloys including 304V stainless steel and 316LVM stainless steel, ferromagnetic materials, paramagnetic materials, alloys containing at least 50% iron by weight, ferromagnetic and paramagnetic compounds such as those in powder form, tantalum powder, barium sulfate, bismuth oxychloride, tungsten, iron oxide nanoparticles, functionalized magnetite, gadolinium, ferritic stainless steel, ferritic stainless steel powder, 316 stainless steel, nylon compounded with another material such as tungsten, bismuth, and others, and any other material deemed suitable for a particular embodiment. Instead of incorporating a marker into the periphery of the elongated member of the medical device, an alternative embodiment can include a marker disposed on a surface of the elongated member, such as the inner or outer surface. For example, the marker can be printed or glued onto the inner or outer surface of the elongated member of the medical device. For example, an ink containing a material having a magnetic susceptibility greater than that of the reinforcing member of the medical device, e.g., an ink containing magnetic particles, an ink containing iron oxide nanoparticles, or an ink containing iron oxide nanoparticles bound to phospholipids, can be printed onto the exterior and / or interior surface of the elongate member to form a marker in the medical device according to some embodiments. The marker can also be disposed on the surface by other suitable processes, such as chemical vapor deposition. Also alternatively, a tape, e.g., a magnetic tape, containing a material having a magnetic susceptibility greater than that of the reinforcing member of the medical device can be adhered to the exterior or interior surface of the elongate member to form a marker in the medical device according to some embodiments.The selection of markers to include in a medical device according to certain embodiments may also be based on the magnetic field strength in which the medical device is intended to be used. For example, a medical device including a marker may be utilized to complete one or more interventional procedures under MRI utilizing one or more magnetic field strengths (0.55T, 1.5T, or 3.0T). Materials may be selected for markers in a medical device according to an embodiment based on these anticipated magnetic field strengths and the anticipated visual artifacts produced by markers formed from particular materials and having particular structural configurations.

[0040] The reinforcing members of the medical device according to the invention have a susceptibility different from that of the markers in the medical device. Thus, the markers of the medical device according to the invention have a susceptibility different from that of the reinforcing material in the medical device. Any combination of materials for these elements that provides this relative relationship of susceptibility for these elements is believed to be critical to the performance of the medical device according to the invention and can be used in the medical device according to certain embodiments. In fact, the reinforcing members and the markers can be made of the same or different materials, so long as the relative relationship of the susceptibility of these elements is provided. In some embodiments, different materials with different magnetic susceptibilities are used for the reinforcing members and the markers. In these embodiments, the reinforcing members and the markers have different susceptibilities and are made of materials with different magnetic susceptibilities. With respect to these embodiments, one skilled in the art will be able to select a material for one of these elements in the medical device according to certain embodiments based on various considerations, including the composition of the other of these elements and any desired performance or imaging characteristics for the medical device. Examples of suitable combinations of different materials for the reinforcing member and the marker include, but are not limited to, a first material for the reinforcing member and a second different material for the marker, such as a paramagnetic material for the reinforcing member and a ferromagnetic material for the marker, an alloy containing 1% or less by weight iron for the reinforcing member and an alloy containing at least 50% by weight iron for the marker, a cobalt chromium alloy for the reinforcing member and a stainless steel for the marker, and a nickel cobalt alloy such as MP35N for the reinforcing member and a stainless steel such as 304V stainless steel or 316LVM stainless steel for the marker. In other embodiments, the reinforcing member and the marker are formed from the same material. In these embodiments, the reinforcing member and the marker have different susceptibilities, but the reinforcing member and the marker have the same magnetic susceptibility. For example, in the embodiment shown, the reinforcing member 128 and the marker 130 can be formed from the same material, giving the reinforcing member 128 and the marker 130 the same magnetic susceptibility.To provide these elements 128, 130 with different susceptibilities, one can be work hardened or engineered in some way to provide a different susceptibility than the other.

[0041] Examples of suitable materials for the reinforcing member include, but are not limited to, metals such as titanium, alloys, e.g., alloys containing 1% or less by weight of iron, such as stainless steels, nickel-containing alloys, cobalt-containing alloys, cobalt-chromium alloys, etc., polymeric materials, such as polyetheretherketone (PEEK), fiberglass, and the like.

[0042] The medical device 100 may include additional optional components. For example, a liner, e.g., a liner formed from a lubricious fluoropolymer such as polytetrafluoroethylene (PTFE), may be disposed on the inner surface 120 of the peripheral wall. Also, a handle, connector, or other component may be attached to the proximal end 112 of the elongate member 110 to aid in handling the medical device 100 during use or to facilitate use of the medical device 100 with other medical devices, such as catheters.

[0043] A medical device according to the present invention can have a variety of configurations depending on the particular medical device application. The medical device shown in Figures 1, 2, 3, 4, 5, 6, and 7 is one exemplary configuration. Figure 8 shows another exemplary medical device 200. The medical device 200 is an introducer sheath that aids in the placement, delivery, or deployment of another interventional medical device, for example, an embolization device, such as a catheter, stent, stent graft, valve, filter, coil, bead, or particle, in the blood vessel of an animal, such as a human. The medical device 200 is similar to the medical device 100 described above, except as detailed below. Thus, the medical device 200 includes an elongate member 210 having a proximal end 212, a distal end 214, a longitudinal axis 202 extending between the proximal end 212 and the distal end 214, and a length 204 extending from the proximal end 212 to the distal end 214. The elongate member 210 has a peripheral wall 216 having an outer surface 218 and an inner surface 220 that defines a lumen 222. The lumen 222 extends from a proximal opening (not shown) on the proximal end 212 to a distal opening 226 on the distal end 214. A reinforcing member 228 is disposed within the peripheral wall 216 and extends along the length 206 of the elongate member 210. The reinforcing member 228 is formed from a first material having a first susceptibility. A first marker 230 is attached to the elongate member 210 and is formed from a second material having a second susceptibility. A second marker 250 is attached to the elongate member 210 and is formed from a third material having a third susceptibility. The first, second, and third materials may be the same or different. The second and third susceptibilities may be the same or different, but each is different from the first susceptibility. A dilator having a tapered distal end can be disposed longitudinally through lumen 222 of elongate member 210 to access and dilate a vascular access site, for example, over a conventional wire guide (not shown).

[0044] In this example, a connector hub 270 is attached about the proximal end 212 of the elongate member 210. The connector hub 270 may include a conventional silicone disk (not shown) to prevent backflow of fluids through the connector hub 270 during use of the medical device 200. The connector hub 270 also includes a side arm 272 to which other components, such as polymer tubing 274 and a Luer lock connector, can be connected for introducing and withdrawing fluids therethrough in a conventional manner.

[0045] In this example, the medical device 200 includes a first marker 230 and a second marker 250. Each of the first marker 230 and the second marker 250 are disposed distal to the stiffening member 228. This positioning of multiple markers, each having a different susceptibility than that of the stiffening member 228, is believed to be advantageous at least for positioning the markers at a location on the axial length of the medical device 200 that will ultimately be positioned at or near a treatment point of a blood vessel and distal to the stiffening member during use of the medical device 200. When used with an imaging modality such as MRI, this positioning, along with the relative susceptibility, provides a desirable imaging artifact that can be used to verify the placement of the distal portion 232 of the medical device 200. EXAMPLES

[0046] FIG. 9 shows an exemplary medical device 300 including an elongate member 310, a reinforcing member 328 comprising a coil formed from MP35N nickel cobalt, and a marker 330 disposed distally from the reinforcing member 328 and comprising a circumferential ring of 304V stainless steel.

[0047] Figures 10 and 11 respectively show artifacts in magnetic resonance images from a prior art medical device having a reinforcing member comprising a stainless steel coil (left side of both figures) and the medical device 300 shown in Figure 9 (right side of both figures). Figure 10 is an image taken under a spin-echo imaging sequence at 1.5T in copper sulfate as the phantom solution. Figure 11 is an image taken under a spin-echo imaging sequence at 3T in copper sulfate as the phantom solution.

[0048] Figures 12 and 13 respectively show artifacts in magnetic resonance images from a prior art medical device having a reinforcing member comprising a stainless steel coil (left side of both figures) and the medical device 300 shown in Figure 9 (right side of both figures). Figure 12 is an image taken under a gradient refocused echo (GRE) imaging sequence at 1.5T in copper sulfate as the phantom solution. Figure 13 is an image taken under a gradient refocused echo (GRE) imaging sequence at 3T in copper sulfate as the phantom solution.

[0049] 14 illustrates artifacts in magnetic resonance images from first, second, and third exemplary medical devices according to an embodiment of the present invention. The first exemplary medical device comprises a coil formed from MP35N nickel cobalt and a single marker disposed distal to the stiffening member and comprising a circumferential band of 304V stainless steel. The second exemplary medical device comprises a coil formed from MP35N nickel cobalt and a single marker disposed distal to the stiffening member and comprising a twisted circumferential band of 304V stainless steel. The third exemplary medical device comprises a coil formed from MP35N nickel cobalt and a single marker disposed distal to the stiffening member and comprising a circumferential band of 316LVM stainless steel.

[0050] FIG. 15 is a schematic diagram of an exemplary method 400 for performing an interventional procedure under MRI.

[0051] A first step 410 includes advancing a distal end of a medical device to a first location within a blood vessel of an animal, such as a human, until a marker of the medical device is disposed at a second location within the blood vessel. Another step 412 includes scanning a portion of the blood vessel including the second location within the blood vessel using a magnetic resonance scanner. Another step 414 includes acquiring a magnetic resonance image of the portion of the blood vessel, such that the image includes an artifact indicative of the presence of the marker within the portion of the blood vessel. Another step 416 includes viewing the artifact in the image generated by the presence of the marker. Another step 418 includes manipulating the medical device based on the location of the artifact relative to the blood vessel. Another step 420 includes removing the medical device from the blood vessel.

[0052] Step 410 of advancing the distal end of the medical device is performed using a medical device according to an embodiment of the present invention, such as any of the exemplary medical devices described herein. Thus, the medical device includes an elongate member defining a lumen, a reinforcing member disposed within a circumferential wall of the elongate member and comprising a metal or alloy having a first magnetic susceptibility, and at least one marker disposed within or otherwise attached to the circumferential wall of the elongate member and comprising a metal or alloy having a second magnetic susceptibility greater than the first magnetic susceptibility.

[0053] Step 412 may be accomplished by scanning a portion of the blood vessel using a magnetic resonance scanner having any suitable number and type of magnetic resonance imaging parameters, such as gradient refocused echo imaging, spin echo imaging, true fast imaging with steady state precession, FLASH (fast low flip angle shot) spoiled gradient echo imaging, magnetic field strengths such as 0.55T, 1.5T, 3T, about 0.055T to 1.5T, and magnetic fields less than 1T, slice thickness, flip angle, field of view, resolution, gradient magnetic fields, and any other imaging parameters deemed suitable for a particular embodiment.

[0054] Step 414 may be accomplished by acquiring a magnetic resonance image from the magnetic resonance scanner used in step 412 .

[0055] Step 416 may be accomplished by reviewing the magnetic resonance images acquired in step 414 and identifying artifacts in the images based on the presence of markers on the medical device.

[0056] Step 418 is performed in a manner that achieves or contributes to the achievement of a desired clinical outcome of method 400 of administering an interventional procedure. Thus, the nature of step 418 of manipulating the medical device will depend on the nature of the medical device and the desired clinical outcome. Examples of suitable actions that may be performed for this step include, but are not limited to, advancing the medical device axially within the body passageway, rotating the medical device within the body passageway, advancing another medical device through a lumen of the elongate member of the medical device, deploying another medical device from a position within the lumen of the elongate member of the medical device, and axially retracting a portion of the medical device to allow the other medical device or a portion of the other medical device to radially expand within the vessel. In an alternative embodiment, step 418 may be omitted from method 400 if manipulation of the interventional medical device is not desired.

[0057] The step of withdrawing 420 the medical device from the blood vessel is performed by axially retracting the medical device from the blood vessel until the distal end of the medical device is no longer disposed within the blood vessel.

[0058] Any of the steps performed by magnetic resonance scanning may be accomplished using any suitable magnetic resonance scanner, such as, for example, a conventional magnetic resonance scanner, a magnetic resonance scanner utilizing a 0.55T magnetic field, a 1.5T magnetic field, a 3T magnetic field, a magnetic field between about 0.055T and 1.5T, a magnetic field less than 1T, and any other magnetic resonance scanner deemed suitable for a particular embodiment.

[0059] A method of manufacturing a medical device includes disposing a reinforcing member formed from a first material and having a first susceptibility within a peripheral wall of an elongate member, and attaching a marker formed from a second material and having a second susceptibility different from the first susceptibility to the peripheral wall of the elongate member. The first and second materials may be the same or different. Thus, the first and second materials may have the same or different magnetic susceptibilities. In one exemplary method, the first and second materials are the same, and a further step of work hardening the marker is included to provide the marker and the reinforcing member with different susceptibilities.

[0060] Those skilled in the art will recognize, upon review of the entire teachings of this disclosure, that various improvements and modifications to the examples described and illustrated herein may be devised, and that various elements and features of one example described and illustrated herein may be combined with various elements and features of other examples without departing from the scope of the invention. Accordingly, the particular arrangements of elements and steps disclosed herein have been selected by the inventors merely to describe and illustrate examples of the invention, and are not intended to limit the scope of the invention or the protection thereof afforded by the full scope of the appended claims and any equivalents thereof.

Claims

1. an elongate member having a proximal end, a distal end, and a peripheral wall having an outer surface and an inner surface defining a lumen; a reinforcing member disposed within the peripheral wall extending along a length of the elongate member, the reinforcing member being formed from a first material and having a first susceptibility; a marker attached to the elongate member, the marker being formed from a second material and having a second susceptibility different from the first susceptibility; Equipped with Medical equipment.

2. the first material and the second material are the same; 2. The medical device of claim 1.

3. the first material and the second material are different; 2. The medical device of claim 1.

4. the first material comprises a paramagnetic material; the second material comprises a ferromagnetic material; 4. The medical device according to claim 3.

5. the first material comprises an alloy containing 1 wt. % or less iron; the second material comprises an alloy containing at least 50% iron by weight; 4. The medical device according to claim 3.

6. the first material comprises a cobalt chromium alloy; the second material comprises a stainless steel alloy; 4. The medical device according to claim 3.

7. the first material comprises a nickel-cobalt alloy; the second material comprises a stainless steel alloy; 4. The medical device according to claim 3.

8. the second material comprises one of 304V stainless steel and 316LVM stainless steel; 8. The medical device of claim 7.

9. the reinforcing member comprising a coil; 2. The medical device of claim 1.

10. the reinforcing member comprises a mesh; 2. The medical device of claim 1.

11. the marker comprises a band; 2. The medical device of claim 1.

12. the marker comprises a torsion ring; 2. The medical device of claim 1.

13. The marker is disposed within the peripheral wall.

2. The medical device of claim 1.

14. the marker is disposed distal to the reinforcing member; 2. The medical device of claim 1.

15. the marker comprises a first marker; a second marker formed from a third material and having a third susceptibility different from the first susceptibility; 2. The medical device of claim 1.

16. the first marker is disposed distal to the reinforcing member; 16. The medical device of claim 15.

17. the second marker is disposed distal to the reinforcing member; 16. The medical device of claim 15.

18. an elongate member having a proximal end, a distal end, and a peripheral wall having an outer surface and an inner surface defining a lumen; a reinforcing member disposed within the peripheral wall, extending along a length of the elongated member and formed from a first material having a first magnetic susceptibility; a marker disposed within the peripheral wall distal to the reinforcing member and formed from a second material having a second magnetic susceptibility different from the first material and greater than the first magnetic susceptibility; Equipped with Medical equipment.

19. the second material comprises one of 304V stainless steel and 316LVM stainless steel; 20. The medical device of claim 18.

20. an elongate member having a proximal end, a distal end, and a peripheral wall having an outer surface and an inner surface defining a lumen; a reinforcing member extending along a length of the elongated member, the reinforcing member including a coil disposed within the peripheral wall, the reinforcing member being formed from a first material having a first magnetic susceptibility; a marker disposed within the peripheral wall distal to the reinforcing member and formed from a second material having a second magnetic susceptibility different from the first material and greater than the first magnetic susceptibility; Equipped with Medical equipment.

Images