Medical device for interventional magnetic resonance imaging

Abstract

The present disclosure relates to medical devices, methods of performing interventional medical treatment under MRI, and methods of manufacturing medical devices. An example 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. A reinforcement member is disposed within the circumferential wall, extends along a length of the elongated member, is formed of a first material, and has a first sensitivity. A marker is attached to the elongate member, formed of a second material, and having a second sensitivity different from the first sensitivity.

Description

Technical Field

[0001] The present disclosure generally relates to the field of medical devices. More specifically, the present disclosure relates to an interventional medical device that can be used for treatment under magnetic resonance imaging (MRI), a method for performing interventional medical treatment under MRI, and a method for manufacturing a medical device. The specific examples described herein relate to an introducer sheath. Background Art

[0002] Interventional procedures performed under MRI have several advantages over X-ray guided interventions. For example, the patient is not exposed to ionizing radiation. Moreover, MRI enables characterization of tissue and fluid flow during interventional procedures. For at least these reasons, the use of interventional MRI is gaining wider acceptance, and the number of procedures that can be performed under MRI is also increasing generally.

[0003] However, the current state of the art provides only a limited number of interventional medical devices suitable for use under MRI, which continues to limit the growth in the use of interventional MRI procedures. As a result, patients have not yet fully benefited from interventional MRI technology, and in fact, for certain treatments, patients are often still only able to choose less convenient and potentially less effective options.

[0004] For example, in the absence of interventional MRI, addressing some conditions requires the use of multiple imaging modalities in the clinical pathway from initial testing to treatment. On a practical level, this use of multiple imaging modalities may require the patient to make multiple visits to a healthcare provider. The conventional treatment of prostate cancer is illustrative, with visualization, biopsy, and treatment performed during three separate patient visits. At the first visit, a scan is completed using a magnetic resonance scanner to produce an image showing the prostate and any abnormalities. The patient then leaves the healthcare provider and waits to view the image. If an abnormality is present, a second patient visit is made so that a biopsy sample of the abnormal tissue can be completed. Software is used to merge the magnetic resonance image with the procedural ultrasound to provide guidance for performing the biopsy. This fusion reduces the value of the diagnostic magnetic resonance image. The patient then again leaves the healthcare provider and waits to view the biopsy sample to determine if further treatment is needed (e.g., if the result of the review is a positive diagnosis of prostate cancer). If further treatment is needed, the patient must make a third visit to the healthcare provider to receive treatment. Completing these three patient visits typically takes several months, preventing the patient from receiving prompt treatment, increasing the overall cost associated with treatment (both for the patient and the healthcare providers involved). In addition, using software to merge images from multiple imaging modalities (such as magnetic resonance images and ultrasound images) has disadvantages, such as image overlay or alignment issues and the possibility of tissue compression and displacement. Ultimately, these shortcomings of current treatment methods may limit the overall effectiveness of the treatment. Interventional MRI has the potential to overcome these shortcomings.

[0005] Therefore, there is a need for new and improved interventional medical devices that can be used for treatment under MRI, methods for performing interventional medical treatment under MRI, and methods for manufacturing medical devices. Summary of the invention

[0006] Described herein are various example interventional medical devices that may be used to perform treatment under MRI, various example methods of performing interventional medical treatment under MRI, and various example methods of manufacturing medical devices.

[0007] An example medical device includes: an elongated 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 elongated member, and formed of a first material and having a first sensitivity; and a marker attached to the elongated member, formed of a second material and having a second sensitivity different from the first sensitivity.

[0008] Another example medical device includes: an elongated 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 elongated member, and formed of a first material having a first sensitivity; and a marker disposed within the circumferential wall, distal to the reinforcing member, and formed of a second material that is different from the first material and has a second sensitivity greater than the first sensitivity.

[0009] Another example medical device includes: an elongated 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 including a coil disposed within the circumferential wall, extending along the length of the elongated member, and formed of a first material having a first sensitivity; a marker disposed within the circumferential wall, distal to the reinforcing member, and formed of a second material that is different from the first material and has a second sensitivity greater than the first sensitivity.

[0010] Another example medical device includes: an elongated 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 elongated member, and formed of a first material having a first magnetic sensitivity; and a marker attached to the elongated member and formed of a second material having a second magnetic sensitivity greater than the first magnetic sensitivity.

[0011] Another example medical device includes: an elongated 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 elongated member, and formed of a first material having a first magnetic sensitivity; and a marker disposed within the circumferential wall, distal to the reinforcing member, and formed of a second material that is different from the first material and has a second magnetic sensitivity greater than the first magnetic sensitivity.

[0012] Another example medical device includes: an elongated 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 including a coil disposed within the circumferential wall, extending along the length of the elongated member, and formed of a first material having a first magnetic sensitivity; and a marker disposed within the circumferential wall, distal to the reinforcing member, and formed of a second material that is different from the first material and has a second magnetic sensitivity greater than the first magnetic sensitivity.

[0013] Another example medical device includes: an elongated 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 comprising a mesh disposed within the circumferential wall, extending along the length of the elongated member, and formed of a first material having a first magnetic sensitivity; and a marker disposed within the circumferential wall, distal to the reinforcing member, and formed of a second material that is different from the first material and has a second magnetic sensitivity greater than the first magnetic sensitivity.

[0014] Also included are various example methods for performing interventional medical procedures under MRI.

[0015] Various example methods of manufacturing medical devices are described.

[0016] These and other example interventional medical devices, methods of performing interventional medical treatments under MRI, and methods of making medical devices may be further understood by reading the following detailed description of selected examples and referring to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a side view of an example medical device.

[0018] Figure 2 yes Figure 1 An enlarged cross-sectional view of the medical device is shown.

[0019] Figure 2A is an enlarged cross-sectional view of an alternative medical device.

[0020] Figure 3 yes Figure 1 An enlarged cross-sectional view of the distal end of a medical device is shown.

[0021] Figure 4 yes Figure 1 A cross-sectional view of the tubular medical device along line AA is shown.

[0022] Figure 5 yes Figure 1 A cross-sectional view of the tubular medical device is shown along line BB.

[0023] Figure 6 yes Figure 1 A cross-sectional view of the tubular medical device is shown along line CC.

[0024] Figure 7 yes Figure 1 A cross-sectional view of the tubular medical device along line DD is shown.

[0025] Figure 8 is a side view of an example introducer sheath.

[0026] Fig. 9 is a side view of another example medical device, including an enlarged view of a distal portion of the medical device.

[0027] Fig.10 2 are magnetic resonance images of a prior art medical device and a medical device according to an embodiment.

[0028] Fig.11 2 are magnetic resonance images of a prior art medical device and a medical device according to an embodiment.

[0029] Fig.12 2 are magnetic resonance images of a prior art medical device and a medical device according to an embodiment.

[0030] Fig.13 2 are magnetic resonance images of a prior art medical device and a medical device according to an embodiment.

[0031] Fig.14 1 and 2 are magnetic resonance images of three medical devices according to the embodiment.

[0032] Fig.15 is a flow chart of an example method of performing an interventional medical treatment. DETAILED DESCRIPTION

[0033] The following detailed description and accompanying drawings describe and illustrate different example interventional medical devices, imaging methods, methods for interventional medical treatment under MRI, and methods for manufacturing medical devices. The description and illustration of these examples are provided to enable those skilled in the art to manufacture and use interventional medical devices and perform imaging methods, methods for interventional medical treatment under MRI, and methods for manufacturing interventional medical devices. They are not intended to limit the scope of the present invention or its protection scope in any way. The present invention can be practiced or implemented in different ways, and the examples described and illustrated herein are not considered to be exhaustive.

[0034] As used herein, the term "attached" refers to one component being fixed to another component so that the components do not completely separate from each other during use according to the intended use of the article including the components in the attached form.

[0035] As used herein, the term "circumference" refers to the outer closed boundary of a body, element, or feature and does not impart any structural configuration to the body, element, or feature.

[0036] As used herein, the term "magnetic susceptibility" refers to an intrinsic property of a material that is related to the degree to which the material becomes magnetized in an applied magnetic field.

[0037] As used herein, the term "marker" refers to a discrete deposition of a first material on a second material such that the first material is visible under MRI and can be distinguished from the second material under MRI; refers to a portion of an interventional device in which a first material has been incorporated into a second material such that the combination of the first material and the second material is visible under MRI and can be distinguished from the second material under MRI; and refers to a portion of an interventional device in which a material forming a portion of the interventional device has been manipulated such that the portion is visible under MRI and can be distinguished from the remainder of the interventional device under MRI.

[0038] As used herein, the term "passive" with respect to a marker refers to a marker that is not powered or is powered only by the electromagnetic field of a magnetic resonance scanner.

[0039] As used herein, the term "susceptibility" if not immediately preceded by "magnetic" refers to the ability of an element to affect an external magnetic field. The sensitivity depends on various characteristics of the element, including its size, density, geometry, volume, and other physical characteristics, as well as the magnetic susceptibility of the material from which the element is formed.

[0040] As used herein, the term "treatment" refers to a medical procedure performed on or in a part of a patient's body. Examples of treatment include delivering a pharmaceutical agent to a site within a body vessel, modifying the local environment within a body vessel (such as by heating or cooling), and removing tissue or a portion of tissue from a site within a patient's body (i.e., a biopsy).

[0041] 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 production method for making the referenced element.

[0042] Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 7 An example medical device 100 is illustrated. The medical device 100 includes an elongated 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 elongated member 110 has a circumferential 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 at the proximal end 112 to a distal opening 126 at the distal end 114. A reinforcing member 128 is disposed within the circumferential wall 116 and extends along the length 106 of the elongated member 110. The reinforcing member 128 is formed of a first material having a first sensitivity. A marker 130 is attached to the elongated member 110 and is formed of a second material having a second sensitivity different from the first sensitivity. The first material and the second material can be the same or different. Thus, the first material and the second material may have the same or different magnetic susceptibilities.

[0043] The elongated member 110 is formed of a polymer material so that the reinforcing member 128 can be disposed within the circumferential wall 116 during the manufacturing process. Any polymer material can be used, and those skilled in the art will be able to select a suitable polymer material for the elongated member in the medical device according to a particular embodiment based on various considerations, including any desired manipulation and performance characteristics of the medical device, such as torsion and pushability. Examples of suitable polymer materials include, but are not limited to, thermoformable polymer materials, such as polyamide materials. These polymer materials are considered desirable, at least because they can melt and flow between and around the elements during thermoforming or heat shrinking. Nylon is considered particularly advantageous, at least because of its easy availability and known properties.

[0044] The elongated member 110 may have any suitable form, and one skilled in the art will be able to select a suitable form for a medical device according to a particular embodiment based on a number of considerations, including the intended use of the medical device and the nature of any body vessel in which the medical device is intended to be placed. In the example shown, the elongated member 110 includes a distal portion 132 that defines a taper 134 along the outer surface 118 such that the diameter of the distal opening 126 is the same as the diameter of the proximal opening 124. For example, the thickness of the circumferential wall 116 may taper over the distal portion 132, while the inner diameter of the lumen 122 is continuous over the distal portion 132. Alternatively, the elongated member 110 may include a distal portion 132 that defines a taper 134 along both the outer surface 118 and the inner surface 120 such that the diameter of the distal opening 126 is smaller than the diameter of the proximal opening 124. Also alternatively, the elongated member 110 may have a substantially continuous outer diameter and inner diameter along its length.

[0045] The elongated member may have any suitable axial length, and those skilled in the art will be able to select a suitable length for a medical device according to a particular embodiment based on various considerations, including the intended use of the medical device and the properties of any body vessel in which the medical device is intended to be placed. Examples of lengths of elongated members considered suitable for use in medical devices according to the present invention include, but are not limited to, equal to, greater than, less than, or approximately 100 cm, 110 cm, 120 cm, 130 cm, 140 cm, 240 cm, 250 cm, 260 cm, 270 cm, 280 cm, a length between about 50 cm to about 350 cm, between about 100 cm to about 280 cm, between about 120 cm to about 260 cm, and any other lengths considered suitable for a medical device according to a particular embodiment.

[0046] like Figure 2 and Figure 4 , the reinforcing member 128 is embedded within the thickness of the circumferential wall 116 of the elongated member 110 such that the reinforcing member 128 is completely disposed within the thickness of the elongated member 110 and such that no portion of the reinforcing member 128 disrupts any portion of the outer surface 118 or the inner surface 120 of the elongated member 110. The reinforcing member 128 surrounds the lumen 122 and extends along the axial length 106 of the elongated member 110. The reinforcing member 128 is formed of a metal or alloy and has a magnetic sensitivity that is less than the magnetic sensitivity of the marker 130.

[0047] The reinforcing member 128 can have any suitable structural configuration relative to the elongated member 110, which provides a desired extension around the lumen 122 and along the axial length 106 of the elongated member 110. Those skilled in the art will be able to select the desired structural configuration of the reinforcing member in the medical device according to a specific embodiment based on various considerations, including any desired handling characteristics of the medical device. In the illustrated embodiment, the reinforcing member 110 includes a wire 135 having a thickness 136 and formed into a coil 138, which extends around the lumen 122 and along the axial length 106 of the elongated member 110. Adjacent turns of the coil 138 are separated by a gap 140. However, the reinforcing member in the medical device according to a specific embodiment can have another structural configuration. For example, the reinforcing member can form an interrupted coil, a coil with a variable pitch along its axial length, a coil with a variable diameter along its axial length, and a combination of these structural configurations. Figure 2A An alternative elongated member 110' is illustrated wherein the reinforcing member 128' comprises a mesh 138' of wire members 135'. Figure 2 As with the illustrated embodiment, the reinforcing member 128' is embedded within the thickness of the circumferential wall 116' such that the reinforcing member 128' is completely disposed within the thickness of the elongated member 110' without any portion of the mesh 138' disrupting the outer surface 118' or the inner surface 120' of the elongated member 110'. Figure 2 Similar to the illustrated embodiment, the reinforcing member 128' extends around the lumen 122' of the elongated 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 (e.g., hexagonal or octagonal cells), or a structure in which the reinforcing member comprises a braided material that extends (e.g., partially, completely) around the lumen of the elongated member and is embedded (e.g., completely) within the thickness of the circumferential wall of the elongated member.

[0048] The sensitivity of the reinforcing member 128 is different from the sensitivity of the marker 130. Therefore, the reinforcing member 128 can be formed of any metal, alloy or other material that provides a desired relative sensitivity compared to the sensitivity of the marker 130. Those skilled in the art will be able to select suitable materials for reinforcing members in medical devices according to specific embodiments based on various considerations, including the composition of the markers in the medical device. Suitable pairings of materials, properties and structural configurations of reinforcing members and markers in medical devices according to the present invention are described in detail below. Examples of suitable materials for reinforcing members include, but are not limited to, titanium, alloys (such as alloys with an iron content of less than or equal to 1% by weight (such as cobalt-chromium alloys)), polymer materials (such as polyetheretherketone (PEEK)), and other materials.

[0049] The reinforcing member 128 may extend along any axial length of the elongated member 110, and one skilled in the art will be able to select a suitable axial length for a medical device according to a particular embodiment based on a variety of considerations, including any desired handling characteristics of the medical device. Figure 1 As best illustrated in , the reinforcement member 128 in the example medical device 100 extends along an axial length 106 that is less than the total axial length 104 of the elongated member 110. The proximal portion 142 of the elongated member 110 includes the proximal end 112 and is devoid of the reinforcement member 128. That is, the reinforcement member 128 terminates and does not extend into the proximal portion 142 of the elongated member 110. Similarly, the distal portion 132 of the elongated member 110 includes the distal end 114 and is devoid of the reinforcement member 128. Therefore, the reinforcement member 128 terminates and does not extend into the distal portion 132 of the elongated member 110. Axially separating the marker 130 from the distal end of the reinforcement member 128 is considered to be particularly advantageous. Given the relative sensitivity of the materials forming these elements, this axial separation of these elements provides desirable imaging characteristics and also provides desirable stiffness to the distal end relative to the portion of the elongated member that includes the reinforcement member, without sacrificing the advantageous handling characteristics imparted to other portions of the elongated member that include the reinforcement member. Thus, as Figure 1 As best shown in FIG. 1 , distal portion 132 of elongated member 110 is devoid of reinforcement member 128. Alternatively, however, the marker may be formed as part of the reinforcement member (e.g., attached to, formed from the same material) such that the material or portion of the material forming the marker has a different sensitivity than the material forming the remainder of the reinforcement member, as described herein.

[0050] Examples of suitable axial lengths of reinforcing members in medical devices according to specific 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 of reinforcing members in medical devices according to specific embodiments include, but are not limited to, between about 50% and about 100% of the axial length of the elongated member of the medical device, between about 60% and about 95% of the axial length of the elongated member of the medical device, between about 70% and about 95% of the axial length of the elongated member of the medical device, between about 80% and about 95% of the axial length of the elongated member of the medical device, and between about 90% and about 95% of the axial length of the elongated member of the medical device.

[0051] like Figure 1 and Figure 6 , the marker 130 is embedded within the thickness of the circumferential wall 116 of the elongated member 110 such that the marker 130 is completely disposed within the thickness of the elongated member 110 and such that no portion of the marker 130 disrupts any portion of the outer surface 118 or the inner surface 120 of the elongated member 110. In the illustrated embodiment, the marker 130 extends around the lumen 122 of the elongated member 110. The marker 130 is a passive marker formed of a metal or alloy having a sensitivity different from that of the reinforcement member 128.

[0052] The marker 130 can have any structural configuration, and one skilled in the art will 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 features when the medical device is used with an imaging modality such as MRI. Examples of suitable configurations include, but are not limited to, a ring, a strip, a plug, a twisted band, a twisted ring, multiple bands attached to each other, multiple rings attached to each other, and other configurations. Figure 1 and 6 The circumferential material band shown is considered to be particularly advantageous. The medical device may also include any number of markers, and those skilled in the art will 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, one, more than one, two, more than one, three, more than three, four, five, six, seven, eight, nine, ten, and more than ten.

[0053] The marker 130 may be disposed at any suitable location relative to the reinforcement member 128, and one skilled in the art will be able to select a suitable location of the marker relative to the reinforcement member in 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. Figure 1 As best shown in FIG. 1 , the marker 130 in the example medical device 100 is located distal to the reinforcing member 128, in a distal portion 132 of the elongated member 110. Other examples of suitable locations include, but are not limited to: within an axial portion of the elongated member that includes the reinforcing member, such that the marker overlaps the reinforcing member; within an axial portion of the elongated member proximal to the reinforcing member; at the distal end of the elongated member; at the proximal end of the elongated member; and combinations of these locations in the case of multiple markers.

[0054] The sensitivity of the marker 130 is different from the magnetic sensitivity of the reinforcing member 128. Accordingly, the marker can be formed of any metal, alloy or other material that provides a desired relative sensitivity compared to the sensitivity of the reinforcing member 128. Those skilled in the art will be able to select suitable materials for the marker in the medical device according to a specific embodiment based on various considerations, including the composition of the reinforcing member in the medical device. The following describes in detail the suitable pairing of the reinforcing member and the material of the marker in the medical device according to the present invention. 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 steel 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 compounds 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, etc.), and any other material considered suitable for a specific embodiment. Instead of incorporating a marker into the circumferential wall of the elongated member of the medical device, an alternative embodiment may include a marker disposed on a surface (e.g., an inner or outer surface) of the elongated member. For example, the marker may be printed or adhered to the inner or outer surface of the elongated member of the medical device. For example, an ink containing a material having a magnetic sensitivity greater than the magnetic sensitivity of the reinforcing member in 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) may be printed onto the outer and / or inner surfaces of the elongated member of the medical device according to the embodiment to form a marker. The marker may also be disposed on the surface by other suitable processes (e.g., chemical vapor deposition). Alternatively, a tape (e.g., a magnetic tape) containing a material having a magnetic sensitivity greater than the magnetic sensitivity of the reinforcing member in the medical device may be adhered to the outer or inner surface of the elongated member of the medical device according to the embodiment to form a marker. The selection of one or more markers to be included in the medical device according to a particular embodiment may also be based on one or more field strengths that the medical device is expected to use. For example, a medical device including a marker can be used to complete one or more interventional procedures under MRI using one or more field strengths (0.55 T, 1.5 T, or 3.0 T). The one or more materials of the one or more markers in a medical device according to an embodiment can be selected based on these desired field strengths and the desired visual artifacts produced by the one or more markers formed of a specific material and having a specific structural configuration.

[0055] The sensitivity of the reinforcing member in the medical device according to the present invention is different from the sensitivity of the marker in the medical device. Therefore, the sensitivity of the marker in the medical device according to the present invention is different from the sensitivity of the reinforcing member in the medical device. Any material pairing of these elements that provides this relative relationship of the sensitivity of these elements (which is considered to be critical to the performance of the medical device according to the present invention) can be used in the medical device according to a specific embodiment. In fact, the reinforcing member and the marker can be formed by the same or different materials, as long as the relative relationship of the sensitivity of these elements is provided. In some embodiments, the reinforcing member and the marker use different materials with different magnetic sensitivities. In these embodiments, the reinforcing member and the marker have different sensitivities and are formed by materials with different magnetic sensitivities. For these embodiments, those skilled in the art will be able to select the material of one of these elements in the medical device according to a specific embodiment based on various considerations, including the composition of another of these elements and any desired performance characteristics or imaging characteristics of the medical device. Examples of suitable pairings of different materials for the reinforcing member and the marker include, but are not limited to: the reinforcing member is made of a first material and the marker is made of a different second material, such as a paramagnetic material for the reinforcing member and a ferromagnetic material for the marker, an alloy containing less than or equal to 1% iron by weight for the reinforcing member and an alloy containing at least 50% iron by weight for the marker, a cobalt-chromium alloy for the reinforcing member and stainless steel for the marker, a nickel-cobalt alloy (such as MP35N) for the reinforcing member and 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 of the same material. In these embodiments, although the reinforcing member and the marker have different sensitivities, the reinforcing member and the marker have the same magnetic sensitivity. For example, in the illustrated embodiment, the reinforcing member 128 and the marker 130 can be formed of the same material, thereby giving the reinforcing member 128 and the marker 130 the same magnetic sensitivity. In order to give these elements 128, 130 different sensitivities, one of the elements can be hardened or manipulated in some way to provide a different sensitivity from the other element.

[0056] Examples of suitable materials for reinforcing members include, but are not limited to, metals (such as titanium), alloys (such as stainless steel, nickel-containing alloys, cobalt-containing alloys, alloys with an iron content of less than or equal to 1% by weight (such as cobalt-chromium alloys)), polymer materials (such as polyetheretherketone (PEEK)), glass fibers, etc.

[0057] The medical device 100 may include additional optional components. For example, a lining, such as a lining formed of a lubricating fluoropolymer (such as polytetrafluoroethylene (PTFE)), may be provided on the inner surface 120 of the circumferential wall. Furthermore, a handle, connector, or other component may be attached to the proximal end 112 of the elongated member 110 to assist in manipulating the medical device 100 during use or to facilitate use of the medical device 100 with other medical devices (such as catheters, etc.).

[0058] Medical devices according to the present invention may take a variety of configurations, depending on the intended use of the particular medical device. Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 7 The medical device shown is an example configuration. Figure 8 Another example medical device 200 is illustrated. The medical device 200 is an introducer sheath that can be used to place, deliver or deploy another interventional medical device, such as a catheter, a stent, a stent graft, a valve, a filter, a coil, an embolic device (such as one or more beads or one or more particles, etc.) into a body vessel of an animal (such as a human). The medical device 200 is similar to the medical device 100 described above, except as described below. Therefore, the medical device 200 includes an elongated 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 elongated member 210 has a circumferential wall 216 having an outer surface 218 and an inner surface 220 defining 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 circumferential wall 216, and the reinforcing member extends along the length 206 of the elongated member 210. The reinforcing member 228 is formed of a first material having a first sensitivity. A first marker 230 is attached to the elongated member 210 and is formed of a second material having a second sensitivity. A second marker 250 is attached to the elongated member 210 and is formed of a third material having a third sensitivity. The first material, the second material, and the third material may be the same or different. The second sensitivity and the third sensitivity may be the same or different, but each is different from the first sensitivity. A dilator with a tapered distal end may be longitudinally penetrated through the lumen 222 of the elongated member 210 for, for example, touching and dilating a vascular access site above a conventional guidewire (not shown).

[0059] In this example, a connector hub 270 is attached around the proximal end 212 of the elongated member 210. The connector hub 270 may include a conventional silicone disc (not shown) for preventing fluid from flowing back through the connector hub 270 during use of the medical device 200. The connector hub 270 also includes a side arm 272 to which a polymer tube 274 and other components (such as a Luerlock connector) may be connected to allow fluid to be introduced and withdrawn therethrough in a conventional manner.

[0060] 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 is disposed distal to the reinforcing member 228. Such positioning of multiple markers, wherein the sensitivity of each marker is different from the sensitivity of the reinforcing member 228, is believed to be advantageous at least because the markers are positioned at a location along the axial length of the medical device 200 and distal to the reinforcing member that is ultimately positioned at or near a treatment site in a body vessel during use of the medical device 200. Such positioning, along with the relative sensitivity, provides a desired imaging artifact when used with an imaging modality such as MRI that can be used to confirm the placement of the distal portion 232 of the medical device 200.

[0061] Example

[0062] Fig. 9 An example medical device 300 is illustrated that includes an elongated member 310, a reinforcement member 328 including a coil formed of MP35N nickel cobalt, and a marker 330 disposed distally of the reinforcement member 328 and including a 304V stainless steel circumferential ring.

[0063] Fig.10 and Fig.11 Artifacts in magnetic resonance images of a prior art medical device having a reinforcement member comprising a stainless steel coil are illustrated (left side of both figures) and Fig. 9 Artifacts in a magnetic resonance image of a medical device 300 are shown (right side of both figures). Fig.10 The images were acquired using a 1.5T spin echo imaging sequence with copper sulfate as the phantom solution. Fig.11 Images were taken at 3T using a spin echo imaging sequence with copper sulfate as the phantom solution.

[0064] Fig.12 and Fig.13 Artifacts in magnetic resonance images of a prior art medical device having a reinforcement member comprising a stainless steel coil are illustrated (left side of both figures) and Fig. 9 Artifacts in a magnetic resonance image of a medical device 300 are shown (right side of both figures). Fig.12Images were taken at 1.5T gradient refocusing echo (GRE) imaging sequence using copper sulfate as phantom solution. Fig.13 Images were taken at 3T using a gradient refocusing echo (GRE) imaging sequence with copper sulfate as the phantom solution.

[0065] Fig.14 Artifacts in magnetic resonance images of first, second, and third example medical devices according to embodiments of the present invention are illustrated. The first example medical device includes a coil formed of MP35N nickel cobalt and a single marker disposed distally of a reinforcing member and comprising a 304V stainless steel circumferential band. The second example medical device includes a coil formed of MP35N nickel cobalt and a single marker disposed distally of a reinforcing member and comprising a 304V stainless steel twisted circumferential band. The third example medical device includes a coil formed of MP35N nickel cobalt and a single marker disposed distally of a reinforcing member and comprising a 316LVM stainless steel circumferential band.

[0066] Fig.15 is a schematic diagram of an example method 400 for performing an interventional medical procedure under MRI.

[0067] An initial step 410 includes advancing a distal end of a medical device to a first location within a body vessel of an animal, such as a human, until a marker of the medical device is disposed at a second location within the body vessel. Another step 412 includes scanning a portion of the body vessel including the second location within the body vessel using a magnetic resonance scanner. Another step 414 includes obtaining a magnetic resonance image of the portion of the body vessel such that the image includes an artifact indicating the presence of the marker within the portion of the body vessel. Another step 416 includes observing the artifact in the image generated due to the presence of the marker. Another step 418 includes manipulating the medical device based on the location of the artifact relative to the body vessel. Another step 420 includes removing the medical device from the body vessel.

[0068] The 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 example medical devices described herein. Thus, the medical device includes: an elongated member defining a lumen; a reinforcing member disposed within a circumferential wall of the elongated member and comprising a metal or alloy having a first magnetic sensitivity; and at least one marker disposed within or otherwise attached to the circumferential wall of the elongated member and comprising a metal or alloy having a second magnetic sensitivity greater than the first magnetic sensitivity.

[0069] Step 412 can be accomplished by scanning the portion of the body vessel using a magnetic resonance scanner having any suitable number and type of magnetic resonance image parameters, such as gradient refocusing echo imaging, spin echo imaging, true steady-state precession fast imaging, fast low flip angle shot spoiled gradient echo imaging, field strength (e.g., 0.55T, 1.5T, 3T, between approximately .055T and 1.5T, and less than 1T), slice thickness, flip angle, field of view, resolution, gradient field, and any other image parameters deemed suitable for a particular embodiment.

[0070] Step 414 may be accomplished by obtaining a magnetic resonance image from the magnetic resonance scanner used in step 412 .

[0071] Step 416 may be accomplished by reviewing the magnetic resonance image obtained in step 414 and identifying artifacts in the image based on the presence of markers in the medical device.

[0072] Step 418 is performed in a manner that achieves or contributes to achieving the desired clinical outcome of the method 400 for performing an interventional medical treatment. 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: axially advancing the medical device within a body passage, rotating the medical device within a body passage, advancing another medical device through the lumen of an elongated member of the medical device, deploying another medical device from a position within the lumen of an elongated member of the medical device, and axially removing a portion of the medical device to allow another medical device or a portion of another medical device to expand radially within a body vessel. In alternative embodiments, step 418 may be omitted from method 400 when manipulation of the interventional medical device is not desired.

[0073] The step 420 of removing the medical device from the body vessel is performed by axially retracting the medical device from the body vessel until the distal end of the medical device is no longer disposed within the body vessel.

[0074] Any of the steps performed by magnetic resonance scanning can be accomplished using any suitable magnetic resonance scanner, such as a conventional magnetic resonance scanner, a magnetic resonance scanner utilizing a 0.55T field, a 1.5T field, a 3T field, a field between approximately .055T and 1.5T, a field less than 1T, and any other magnetic resonance scanner deemed suitable for a particular embodiment.

[0075] A method of manufacturing a medical device includes: positioning a reinforcing member formed of a first material and having a first sensitivity within a circumferential wall of an elongated member; and attaching a marker formed of a second material and having a second sensitivity different from the first sensitivity to the circumferential wall of the elongated member. The first material and the second material can be the same or different. Thus, the first material and the second material can have the same or different magnetic sensitivities. In an example method, the first material and the second material are the same, and an additional step of work hardening the marker is included so that the marker and the reinforcing member have different sensitivities.

[0076] Those skilled in the art will appreciate that various modifications and alternatives to the described and illustrated examples may be developed based on the overall teachings of this disclosure, 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 present invention. Accordingly, the inventors have selected the specific arrangements of elements and steps disclosed herein for the purpose of describing and illustrating examples of the present invention only, and are not intended to limit the scope of the present invention or its scope of protection, which shall be limited by the full scope of the appended claims and any and all equivalents thereof.

Claims

1. A medical device comprising: an elongated member having a proximal end, a distal end, and a circumferential wall having an outer surface and an inner surface defining a lumen; a reinforcement member disposed within the circumferential wall, extending along the length of the elongated member, and formed of a first material and having a first sensitivity; as well as A marker is attached to the elongated member and is formed of a second material and has a second sensitivity different from the first sensitivity.

2. The medical device according to claim 1, wherein: The first material and the second material are the same.

3. The medical device according to claim 1, wherein: The first material and the second material are different.

4. The medical device according to claim 3, wherein: The first material includes a paramagnetic material and the second material includes a ferromagnetic material.

5. The medical device according to claim 3, wherein: The first material comprises an alloy containing less than or equal to 1% iron by weight, and the second material comprises an alloy containing at least 50% iron by weight.

6. The medical device according to claim 3, wherein: The first material includes a cobalt-chromium alloy and the second material includes a stainless steel alloy.

7. The medical device according to claim 3, wherein: The first material includes a nickel-cobalt alloy and the second material includes a stainless steel alloy.

8. The medical device according to claim 7, wherein: The second material includes one of 304V stainless steel and 316LVM stainless steel.

9. The medical device according to claim 1, wherein: The reinforcement member includes a coil.

10. The medical device according to claim 1, wherein: The reinforcement member includes a mesh.

11. The medical device according to claim 1, wherein: The marking includes a band.

12. The medical device according to claim 1, wherein: The marker includes a twisted loop.

13. The medical device according to claim 1, wherein: The marking is disposed within the circumferential wall.

14. The medical device according to claim 1, wherein: The marking is disposed on the distal side of the reinforcing member.

15. The medical device of claim 1, wherein: The marking includes a first marking; and The medical device further includes a second marker formed of a third material and having a third sensitivity different from the first sensitivity.

16. The medical device of claim 15, wherein: The first marking is disposed on the distal side of the reinforcing member.

17. The medical device of claim 15, wherein: The second marking is disposed on the distal side of the reinforcing member.

18. A medical device comprising: an elongated member having a proximal end, a distal end, and a circumferential wall having an outer surface and an inner surface defining a lumen; a reinforcement member disposed within the circumferential wall, extending along the length of the elongated member, and formed of a first material having a first magnetic susceptibility; as well as A marker is disposed within the circumferential wall, distal to the reinforcing member, and is formed of a second material that is different from the first material and has a second magnetic susceptibility greater than the first magnetic susceptibility.

19. The medical device of claim 18, wherein: The second material includes one of 304V stainless steel and 316LVM stainless steel.

20. A medical device comprising: an elongated member having a proximal end, a distal end, and a circumferential wall having an outer surface and an inner surface defining a lumen; a reinforcement member including a coil disposed within the circumferential wall, extending along the length of the elongated member, and formed of a first material having a first magnetic susceptibility; as well as A marker is disposed within the circumferential wall, distal to the reinforcing member, and is formed of a second material that is different from the first material and has a second magnetic susceptibility greater than the first magnetic susceptibility.

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