Medical systems, devices, and kits useful in performing treatment under magnetic resonance imaging, and related methods

Abstract

An exemplary medical system, as well as associated devices, kits, and methods, for performing treatment under magnetic resonance imaging are described. The exemplary medical system includes a first medical device, a second medical device, and a marker. The first medical device is formed of a first material. The first material has a first magnetic susceptibility. The second medical device is formed of a second material. The second material has a second magnetic susceptibility. The marker is disposed on the second medical device and is formed of a third material. The third material has a third magnetic susceptibility different from the first magnetic susceptibility and the second magnetic susceptibility.

Description

[Technical field]

[0001] The present disclosure relates generally to the field of medical systems and devices. More particularly, the present disclosure relates to a medical system useful for performing a procedure under magnetic resonance imaging (MRI), a medical device useful for performing a procedure under MRI, a kit useful for performing a procedure under MRI, and a method of performing an interventional procedure under MRI. [Background technology]

[0002] The field of interventional MRI has gained widespread acceptance and has seen an increase in the number of procedures that can be performed. Interventional procedures performed under MRI have several advantages over X-ray guided interventions. For example, patients are not exposed to ionizing radiation. MRI also offers the ability to characterize tissue and functional blood flow during interventional procedures.

[0003] The development of MRI-guided interventional procedures has been limited by the unavailability of the tools required to perform these procedures. Thus, patients must make multiple visits to treatment centers for visualization, diagnosis, and treatment of various conditions. In addition, multiple imaging modalities are often required, which impacts the accuracy of using magnetic resonance (MR) images in prescribing interventions. For example, when dealing with prostate cancer, currently, a patient would make three visits to complete visualization, biopsy, and treatment. During the first visit, a scan is performed using an MR scanner to generate images showing the prostate and any abnormalities. The patient then leaves the center and awaits the results of the image review. If abnormalities are present, a second patient visit is performed so that a biopsy sample of the abnormal tissue can be obtained. Currently, software is used that fuses the manual ultrasound and MR images to provide guidance in performing the biopsy. This fusion reduces the usefulness of the diagnostic MR images. The patient then leaves the center again and awaits the results of the biopsy sample review to determine whether further treatment is required (e.g., whether the review is positive for prostate cancer). If further treatment is required, the patient will make a third visit to the facility so that the treatment can be administered. Completion of these three patient visits can take several months, preventing patients from receiving prompt treatment and increasing the overall costs associated with treatment. Additionally, the software used to fuse MR images with other images (e.g., images acquired via ultrasound) has shortcomings, including potential issues with image overlay and the possibility of misalignment due to compression of tissue (e.g., prostate).

[0004] Thus, there is a need for new and improved medical systems useful in performing MRI-guided procedures, medical devices useful in performing MRI-guided procedures, kits useful in performing MRI-guided procedures, and methods of performing MRI-guided interventional procedures. Summary of the Invention [Problem to be solved by the invention]

[0005] Described herein are various exemplary medical systems useful in performing procedures under MRI, medical devices useful in performing procedures under MRI, kits useful in performing procedures under MRI, and methods of performing interventional procedures under MRI. [Means for solving the problem]

[0006] An exemplary medical system useful in performing treatment under MRI includes a first medical device, a second medical device, and a marker. The first medical device is formed of a first material. The first material has a first magnetic susceptibility. The second medical device is formed of a second material. The second material has a second magnetic susceptibility. The marker is disposed on the second medical device and is formed of a third material. The third material has a third magnetic susceptibility different from the first magnetic susceptibility and the second magnetic susceptibility.

[0007] An exemplary medical device useful in performing treatment under MRI includes an elongate member and a plug. The elongate member has a proximal end, a distal end, and a body formed of a first material having a first magnetic susceptibility. The plug is disposed on the elongate member and includes a second material disposed within a third material. The second material has a second magnetic susceptibility. The third material has a third magnetic susceptibility. The second magnetic susceptibility is different from the first magnetic susceptibility and the third magnetic susceptibility.

[0008] An exemplary kit useful in performing a treatment under magnetic resonance includes a first medical device, a second medical device, and a third medical device. The first medical device includes a first marker that produces a first image artifact under a first MR magnetic field strength. The second medical device includes a second marker that produces a second image artifact under a second MR magnetic field strength. The third medical device includes a third marker that produces a third image artifact under a third MR magnetic field strength. The first MR magnetic field strength is different from the second MR magnetic field strength and the third MR magnetic field strength. The second MR magnetic field strength is different from the third MR magnetic field strength. The first image artifact has a first set of characteristics (e.g., size, shape, pattern, and / or strength) under the first MR magnetic field strength, a second set of characteristics under the second MR magnetic field strength, and a third set of characteristics under the third MR magnetic field strength. The first set of characteristics of the first image artifact is different from the second set of characteristics of the first image artifact and the third set of characteristics of the first image artifact. The second set of characteristics of the first image artifact is different from the third set of characteristics of the first image artifact. The second image artifact has a first set of characteristics under a first MR magnetic field strength, a second set of characteristics under a second MR magnetic field strength, and a third set of characteristics under a third MR magnetic field strength. The first set of characteristics of the second image artifact is different from the second set of characteristics of the second image artifact and the third set of characteristics of the second image artifact. The second set of characteristics of the second image artifact is different from the third set of characteristics of the second image artifact. The third image artifact has a first set of characteristics under a first MR magnetic field strength, a second set of characteristics under a second MR magnetic field strength, and a third set of characteristics under a third MR magnetic field strength. The first set of characteristics of the third image artifact is different from the second set of characteristics of the third image artifact and the third set of characteristics of the third image artifact. The second set of characteristics of the third image artifact is different from the third set of characteristics of the third image artifact.

[0009] An exemplary method of performing an interventional treatment under MRI includes positioning a patient in an MR scanner, scanning a first portion of the patient using the MR scanner, acquiring MR images of the first portion of the patient, identifying tissue having predefined characteristics using the MR images, selecting a procedure to treat the tissue based on the predefined characteristics, selecting an MR sequence and / or parameters to use in performing the selected procedure, selecting a medical device to perform the medical procedure based on the selected MR sequence and / or parameters intended to be used in performing the selected procedure, inserting the medical device into a body passage and to the tissue while scanning a second portion of the patient including the medical device using the MR scanner while keeping the patient positioned in the MR scanner used to scan the portion of the patient, acquiring MR images of the second portion of the patient including the medical device, verifying the position of the medical device in the body passage, and performing the treatment using the medical device.

[0010] These exemplary medical systems, medical devices, kits, and methods can be further understood upon consideration of the following detailed description and accompanying drawings. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a partial elevational view of a first exemplary medical system including a first exemplary medical device and a second exemplary medical device. [Diagram 2] 2 is an elevational view of a first exemplary medical device included in the medical system shown in FIG. 1. [Diagram 3] 2 is an elevational view of a second exemplary medical device included in the medical system shown in FIG. 1. [Figure 4] FIG. 3 is an enlarged view of area A in FIG. [Diagram 5] FIG. 4 is an enlarged view of area B in FIG. [Figure 6] 6 is a cross-sectional view of the second medical device shown in FIG. 3 taken along line 6-6. [Figure 7]1 is a graph showing simulated magnetic susceptibility of several diamagnetic and paramagnetic metals and metal alloys. [Figure 8] 1 is a graph showing simulated magnetization saturation of several ferromagnetic metals and metal alloys. [Figure 9] 13A-C are simulated magnetic field perturbations and image artifacts of a medical device having various metal alloy markers including 304V cold work stainless steel. [Figure 10] 13A-C are simulated magnetic field perturbations and image artifacts of medical devices having various metal alloy markers including 304V annealed stainless steel. [Figure 11] 1 is a partial perspective view of an exemplary alternative medical device that may be included in the medical system. [Figure 12] 12 is a cross-sectional view of the medical device shown in FIG. 11 along line 12-12. [Figure 13] 1 is a cross-sectional view of another exemplary alternative medical device that may be included in the medical system. [Figure 14] 1 is a cross-sectional view of another exemplary alternative medical device that may be included in the medical system. [Figure 15] FIG. 13 is a partial perspective view of another exemplary alternative medical device that may be included in the medical system. [Figure 16] FIG. 13 is a partial perspective view of another exemplary alternative medical device that may be included in the medical system. [Figure 17] FIG. 17 is an enlarged view of area C in FIG. [Figure 18] FIG. 18 is an enlarged view of area D in FIG. [Figure 19] This is an enlarged view of 304L plastic blended fine powder. [Figure 20] This is an enlarged view of 430L plastic compound coarse powder with a small surface area. [Figure 21] This is an enlarged view of 430L plastic compound coarse powder with a large surface area. [Figure 22]Shown are a solid foil AD-MU-80 plug, an epoxy plug, a plug comprising SS316 dispersed in a bulk material (e.g., epoxy), and a plug comprising SS430L dispersed in a bulk material (e.g., epoxy), each plug held in place using epoxy. [Figure 23] The plug shown in FIG. 22 is shown under gradient refocusing echo (GRE) MR imaging at 3.0 Tesla (T). [Figure 24] The plug shown in FIG. 22 is shown under 3.0T spin-echo (SE) MR imaging. [Diagram 25] FIG. 13 is a partial perspective view of another exemplary alternative medical device that may be included in the medical system. [Figure 26] 1A-1C are elevational views of an exemplary alternative set of medical devices that may be included in a medical system. [Figure 27] A control medical device and the medical device shown in FIG. 26 are shown in a copper sulfate phantom solution at 0.55T. [Figure 28] A control medical device and the medical device shown in FIG. 26 are shown in a copper sulfate phantom solution at 1.5T. [Figure 29] A control medical device and the medical device shown in FIG. 26 are shown in porcine tissue at 0.55T. [Diagram 30] 27 shows the medical device shown in FIG. 26 in porcine tissue at 1.5T. [Diagram 31] 1 shows an exemplary kit useful in performing a procedure under MRI. [Diagram 32] FIG. 1 is a schematic diagram of an exemplary method for performing a treatment under MRI. [Diagram 33] FIG. 2 is another schematic diagram of an exemplary method of performing a treatment under MRI. [Diagram 34] FIG. 2 is another schematic diagram of an exemplary method of performing a treatment under MRI. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The following detailed description and accompanying drawings describe and illustrate various exemplary medical systems useful in performing treatments under MRI, medical devices useful in performing treatments under MRI, kits useful in performing treatments under MRI, and methods of performing interventional treatments under MRI. The descriptions and illustrations of these examples are provided to enable one skilled in the art to make and use the medical systems, medical devices, kits, and methods of performing interventional treatments under MRI. These descriptions and illustrations are not intended to limit in any manner the scope of the invention or the protection sought. The invention can be practiced or carried out in various ways, and the examples described and illustrated herein are merely selected examples of various ways to practice or carry out the invention and are not to be considered exhaustive.

[0013] As used herein, the term "attached" refers to one member being fixed to another member such that the members do not completely separate from one another when used in accordance with the intended use of the item that includes the member in the attached configuration.

[0014] As used herein, the term "plug" refers to a member having a size and configuration suitable for placement within a hole, passage, recess, or void in another member. The term does not mandate any particular size or configuration, and the size and configuration of a particular plug will depend on the size and configuration of the hole, passage, recess, or void into which the plug is intended to be placed.

[0015] As used herein, the term "circumference" refers to a boundary that surrounds the exterior or interior of a body, element, or feature and does not impart any structural organization to the body, element, or feature.

[0016] As used herein, the term "marker" refers to a first material discretely deposited 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 the first material is incorporated into the 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 / or a portion of an interventional device where the material forming the portion of the interventional device has been manipulated such that the portion is visible under MRI and distinguishable from the remainder of the interventional device under MRI.

[0017] As used herein, the term "passive" in relation to a marker refers to a marker that is not powered or is powered only by the electromagnetic field of the MR scanner.

[0018] As used herein, the term "treatment" refers to a medical procedure performed on or at a portion of a patient's body. Examples of treatments include delivery of a drug to a site within a body vessel, altering the local environment within a body vessel, such as by heating or cooling, and removal of tissue or a portion of tissue from a site within a patient's body (i.e., a biopsy).

[0019] As used herein, the term "magnetic susceptibility" refers to an intrinsic property of a material related to how much it becomes magnetized in an applied magnetic field.

[0020] As used herein, the term "susceptibility," which does not include "magnetic," refers to the ability of an element to affect an external magnetic field. Susceptibility depends on various properties of the element, including its size, density, volume, geometric configuration, and other physical properties, as well as the magnetic susceptibility of the material from which the element is formed.

[0021] 1 , 2 , 3 , 4 , 5 and 6 show a first exemplary medical system 8. In this example, the first exemplary medical system 8 comprises a first medical device 10 and a second medical device 50.

[0022] In the illustrated embodiment, the first medical device 10 is a cannula 12 and the second medical device 50 is a stylet 52 that may be used coaxially with the first medical device 10. The cannula 12 has a hub member 14 and an elongate member 16. The hub member 14 has a proximal end 18, a distal end 20, and a body 22 that defines a lumen 24 and a protrusion 26. The hub member 14 provides a mechanism for attaching other devices (e.g., a second medical device 50) to the cannula 12. The lumen 24 extends from the proximal end 18 to the distal end 20 to allow one or more devices to pass through and within the hub member 14. The elongate member 16 has a proximal end 30, a distal end 32, a length 31, an inner diameter 33, an outer surface 34, an inner surface 36, and a body 38 defining a lumen 40 and a tapered distal tip 42 having a cutting edge 44. The lumen 40 extends from the proximal end 30 to the distal end 32 such that one or more devices can be passed through and within the elongate member 16 of the cannula 12. In the illustrated embodiment, the elongate member 16 of the cannula 12 is formed of a first material having a first magnetic susceptibility.

[0023] The stylet 52 has a hub member 54 and an elongate member 56. The hub member 54 has a proximal end 58, a distal end 60, and a body 62 defining a recess 64. The hub member 54 provides a mechanism for attaching another device (e.g., the first medical device 10) to the stylet 52. The recess 64 extends into the body 62 from a location between the proximal end 58 and the distal end 60 toward the proximal end 58. The recess 64 is sized to receive the protrusion 26 defined by the hub member 14 of the cannula 12 such that a releasable attachment between the cannula 12 and the stylet 52 may be accomplished. The elongate member 56 has a proximal end 66, a distal end 68, a length 67, an outer diameter 69, an outer surface 70, and a body 72 defining a solid member having a tapered distal tip 74 having a cutting edge 76. The length 67 of the elongate member 56 of the stylet 52 is greater than the length 31 of the elongate member 16 of the cannula 12. The outer diameter 69 of the elongate member 56 of the stylet 52 is less than the inner diameter 33 of the elongate member 16 of the cannula 12. This structural configuration allows the elongate member 56 of the stylet 52 to pass through and through the lumen 24 of the hub member 14 and the lumen 40 of the elongate member 16 of the cannula 12, as shown in FIG. 1. The elongate member 56 of the stylet 52 is formed of a second material having a second magnetic susceptibility. In the illustrated embodiment, the first material forming the elongate member 16 of the cannula 12 and the second material forming the elongate member 56 of the stylet 52 are the same.

[0024] The elongate member 56 of the stylet 52 includes a plurality of markers 78. Each marker of the plurality of markers is disposed around the entire circumference of the body 72 of the elongate member 56 of the stylet 52. Each marker of the plurality of markers 78 is a band of material attached to the stylet 52 and is formed of a material that is different from the first and second materials and has a different (e.g., greater or lesser) magnetic susceptibility than the first and second magnetic susceptibility. In the illustrated embodiment, the first and second materials are formed of materials that are not susceptible to magnetism or have a low magnetic susceptibility relative to the magnetic susceptibility of the material forming the markers included in the medical device (e.g., non-paramagnetic, non-ferromagnetic, non-diamagnetic materials), and the material used to form the markers of the plurality of markers 78 is a material that is susceptible to magnetism, i.e., a material that has a high magnetic susceptibility magnitude relative to the magnetic susceptibility magnitude of the material forming another portion of the medical device (e.g., the elongate member). Thus, the material forming the marker has a magnetic susceptibility different from (eg, greater than or less than) the first magnetic susceptibility and the second magnetic susceptibility.

[0025] The plurality of markers 78 includes a first subset of markers 80, a second subset of markers 82, and a third subset of markers 84. Each marker in the first subset of markers 80 is disposed between the proximal end 66 and the distal end 68 of the elongate member 56 of the second medical device 50 and is formed of a third material that is different from the first material and the second material and has a third magnetic susceptibility different (e.g., greater than or less than) the first magnetic susceptibility and the second magnetic susceptibility. Each marker in the second subset of markers 82 is disposed between the first subset of markers 80 and the third subset of markers 84 and is formed of a fourth material that is different from the first material, the second material, and the third material and has a fourth magnetic susceptibility different (e.g., greater than or less than) the first magnetic susceptibility and the second magnetic susceptibility and different (e.g., greater than or less than) the third magnetic susceptibility. However, alternative embodiments may include markers in the second subset of markers formed of a fourth material that is different from the first and second materials and the same as a third material, and / or has a fourth magnetic susceptibility different from (e.g., greater than or less than) the first and second magnetic susceptibility and has the same magnetic susceptibility, the same susceptibility, or a different susceptibility than the third magnetic susceptibility. Each marker in the third subset of markers 84 is disposed between the second subset of markers 82 and the distal end 68 of the elongate member 56 of the stylet 52 and is formed of a fifth material that is different from the first, second, third, and fourth materials and has a fifth magnetic susceptibility different from (e.g., greater than or less than) the first and second magnetic susceptibility and different from (e.g., greater than or less than) the third and fourth magnetic susceptibility. However, alternative embodiments may include markers in the third subset of markers, each marker being formed of a fifth material that is different from the first material and the second material and the same as the third material and / or the fourth material, and / or has a fifth magnetic susceptibility that is different from (e.g., greater than or less than) the first magnetic susceptibility and the second magnetic susceptibility, and has the same magnetic susceptibility, the same susceptibility, or a different susceptibility as the third magnetic susceptibility and / or the fourth magnetic susceptibility.In the illustrated embodiment, the first subset of markers 80 includes three markers, the second subset of markers 82 includes one marker, and the third subset of markers 84 includes one marker. However, alternative embodiments may include any suitable number of markers in the subsets of the plurality of markers. Alternatively, the medical device may comprise a plurality of markers including a first marker, a second marker, and a third marker. The first marker may produce a first image artifact under a first magnetic field strength and / or a first MR sequence, the second marker may produce a second image artifact under a second magnetic field strength and / or a second MR sequence, and the third marker may produce a third image artifact under a third magnetic field strength and / or a third MR sequence. The first image artifact is different from the second image artifact and the third image artifact. The second image artifact is different from the third image artifact. The first MR magnetic field strength is different from the second MR magnetic field strength and the third MR magnetic field strength. The second MR magnetic field strength is different from the third MR magnetic field strength. The first image artifact has a first set of characteristics (e.g., size, shape, pattern, and / or intensity) under the first MR magnetic field strength, a second set of characteristics under the second MR magnetic field strength, and a third set of characteristics under the third MR magnetic field strength. The first set of characteristics of the first image artifact is different from the second set of characteristics of the first image artifact and the third set of characteristics of the first image artifact. The second image artifact has a first set of characteristics under the first MR magnetic field strength, a second set of characteristics under the second MR magnetic field strength, and a third set of characteristics under the third MR magnetic field strength. The first set of characteristics of the second image artifact is different from the second set of characteristics of the second image artifact and the third set of characteristics of the second image artifact. The second set of characteristics of the second image artifact is different from the third set of characteristics of the second image artifact.The third image artifact has a first set of characteristics under the first MR magnetic field strength, a second set of characteristics under the second MR magnetic field strength, and a third set of characteristics under the third MR magnetic field strength. The first set of characteristics of the third image artifact is different from the second set of characteristics of the third image artifact and the third set of characteristics of the third image artifact. The second set of characteristics of the third image artifact is different from the third set of characteristics of the third image artifact.

[0026] Alternatively, the medical system may include a first medical device and a second medical device. Each of the first medical device and the second medical device includes a plurality of markers including a first marker, a second marker, and a third marker. The first marker may cause a first image artifact under a first magnetic field strength and / or a first MR sequence, the second marker may cause a second image artifact under a second magnetic field strength and / or a second MR sequence, and the third marker may cause a third image artifact under a third magnetic field strength and / or a third MR sequence. The first image artifact is different from the second image artifact and the third image artifact. The second image artifact is different from the third image artifact. Alternatively, the markers (e.g., the first marker, the second marker, and the third marker) may overlap to cause image artifacts under the first magnetic field strength, the second magnetic field strength, and / or the third magnetic field strength.

[0027] The first material forming the elongate member 16 of the first medical device 10, the second material forming the elongate member 56 of the second medical device 50, and the materials forming any markers included in the medical devices may include any suitable material having a magnetic susceptibility as described herein. For example, the first material, the second material, the third material, the fourth material, and / or the fifth material may include any suitable MRI compatible material having a magnetic susceptibility as described herein. Additionally or in alternative embodiments, the first material, the second material, the third material, the fourth material, the fifth material, and / or any other material described herein may include any suitable MRI compatible material having a magnetic susceptibility or relative susceptibility as well as a susceptibility or relative susceptibility to the portions of the system or device from which the materials form as described herein. In the illustrated embodiment, the first material and the second material each include titanium, each marker in a first subset 80 of the plurality of markers 78 is formed of stainless steel (e.g., 304V SS), each marker in a second subset 82 of the plurality of markers 78 is formed of a first alloy including less than 1% iron by weight, and each marker in a third subset 84 of the plurality of markers 78 is formed of a second alloy including less than 1% iron by weight, where the second alloy may be the same or different from the first alloy (e.g., the second alloy has the same or different magnetic susceptibility as the first alloy and the second alloy has the same or different susceptibility as the first alloy). In a more specific embodiment, each of the first material and the second material includes titanium, each marker in a first subset 80 of the plurality of markers 78 is formed of a stainless steel (e.g., 304V SS), each marker in a second subset 82 of the plurality of markers 78 is formed of a first cobalt chromium alloy (e.g., FWM1537(Co-Cr)), and each marker in a third subset 84 of the plurality of markers 78 is formed of a second cobalt chromium alloy (e.g., L605(Co-Cr)) that is different from the first cobalt chromium alloy. By using these materials, each marker in the plurality of markers 78 acts as a passive marker when producing MR images using MRI.

[0028] Although particular materials have been described as forming the elongate member 16 of the cannula 12, the elongate member 56 of the stylet 52, and each marker in the plurality of markers 78, the medical devices, or portions thereof (e.g., the elongate members), and the markers may be formed of any suitable material having a magnetic susceptibility as described herein. For example, the first medical device, the second medical device, and the markers included in the medical devices may be formed of any suitable MRI compatible material having a magnetic susceptibility as described herein. The selection of an appropriate material may be based on various considerations, including the intended use of the first medical device, the second medical device, and / or the markers.Examples of materials that may be suitable for forming the first medical device, the second medical device, and / or the marker, or a portion thereof, include biocompatible materials, materials that can be made into biocompatible materials, MRI compatible materials, non-ferromagnetic materials such as metals, electrically insulating materials, non-conductive materials, materials that are not susceptible to magnetism, non-diamagnetic materials, passive materials, diamagnetic materials (e.g., pyrolytic carbon), paramagnetic materials, or ferromagnetic materials, magnetically susceptible materials, ferromagnetic passive materials, including ferritic stainless steels, ferritic stainless steel 430L powder, nickel-titanium based alloys such as Nitinol, shape memory alloys, austenitic nickel-chromium based alloys such as Inconel (e.g., Inconel 625), a family of austenitic nickel-chromium based superalloys from Special Metals Corporation, including austenitic stainless steels, stainless steel 304V SS, stainless steel containing iron, stainless steel including Inconel, iron, cobalt, cobalt chrome, cobalt chrome alloys, titanium, materials with a hardness of about 192 KSI (e.g., stainless steel), nickel, nickel plating, bright nickel plating, nickel strike plating, alloys containing less than 1% iron by weight, metals including murinite, such as MuMetal, a brand of nickel-iron ferromagnetic alloy with very high magnetic permeability from Magnetic Shield Corporation, plastics, polymers, PEEK, carbon filled PEEK, polyethylene such as high density polyethylene (HDPE), polypropylene, polycarbonate, silicone, Delrin, ceramics, transparent materials, opaque materials, materials described herein, combinations of materials described herein, or any other material deemed suitable for a particular embodiment. The markers included in the medical device provide a mechanism for using the medical device under MRI such that the markers provide distinct indicators that provide prominence in the portion of the medical device where the markers are placed (e.g., elongate member, tip).When a medical device includes two or more markers as described herein, a first marker may have a first salience under MRI (e.g., cause a first image artifact under MRI) and a second marker may have a second salience under MRI (e.g., cause a second image artifact under MRI), which may be the same or different from the first salience depending on the materials forming the first and second markers. This may be accomplished by forming the markers of the same or different materials and / or by having a larger volume of one material relative to another.

[0029] FIG. 7 is a graph showing simulated magnetic susceptibility of several diamagnetic and paramagnetic metals and metal alloys that may be used to form the first medical device, the second medical device, and / or the marker. FIG. 8 is a graph showing simulated magnetization saturation of several ferromagnetic metals and metal alloys that may be used to form the first medical device, the second medical device, and / or the marker. As described herein, the marker may be formed of any suitable material having a magnetic susceptibility as described herein. FIG. 9 is a simulated magnetic field perturbation and image artifact of a medical device having various metal alloy markers including 304V cold work stainless steel. FIG. 10 is a simulated magnetic field perturbation and image artifact of a medical device having various metal alloy markers including 304V annealed stainless steel.

[0030] A medical system such as that described herein may include any suitable number and type of medical devices. For example, the first medical device may include any suitable type of cannula having any suitable length and gauge, and the second medical device may include any suitable type of stylet having any suitable length and gauge. For example, the first medical device may include an Inconel Chiba needle, an Inconel micropuncture needle, or any other needle deemed suitable for a particular embodiment, and may have a length equal to, greater than, or less than 7 centimeters, 15 centimeters, or any other length deemed suitable for a particular embodiment, and / or may have a gauge equal to, greater than, or less than 20, 21, 22, or any other gauge deemed suitable for a particular embodiment. Any of the medical systems and / or medical devices described herein may be utilized individually or in combination with another medical system and / or medical device.

[0031] According to one embodiment, any suitable number of markers may be disposed on a medical device. Although the second medical device 50 includes five markers 78, it should be appreciated that a medical device according to one embodiment may include any number of markers as deemed suitable for the intended use of a particular medical device, and each marker may be disposed in any suitable location on any suitable component of the medical device. Examples of suitable numbers of markers to include on a medical device according to one embodiment include one marker, two markers, three or more markers, three markers, multiple markers, four markers, five markers, six markers, seven markers, eight markers, nine markers, ten markers, and eleven or more markers. Additionally, in embodiments including two or more markers, the markers may be spaced apart from one another by any desired distance. However, it should be noted that because the markers produce visual artifacts and their usefulness in a medical device is based on the production of these visual artifacts in MR procedures, it is desirable to space the markers on the medical device at a distance that does not result in overlapping or nearly overlapping visual artifacts. However, alternative embodiments may include markers that are spaced at a distance that would produce overlapping visual artifacts. For example, overlapping visual artifacts may occur under one type of MR image sequence (e.g., gradient refocusing echo) but not under another type of MR image sequence (e.g., spin echo).

[0032] Although each marker of the plurality of markers 78 has been shown as a marker band (e.g., a circumferential marker) disposed on the outer surface 70 of the elongate member 56 of the stylet 52, the markers may include any suitable structure attached to or treatment applied to the medical device (e.g., stylet, cannula). For example, the markers may have any suitable shape and may include bands of material, magnetic ink, sputtered magnetite, dimpling, swaging, or peening of material that forms a portion of the medical device (e.g., annealed 304 stainless steel), and / or a single layer or multiple layers of one or more materials (e.g., metals, metal alloys) deposited along the outer and / or inner surface of the medical device (e.g., the elongate member of the medical device) to form a distinct marker visible under MRI. Any suitable marker may be included on the medical device, such as those described herein. Examples of markers that may be suitable for inclusion on a medical device are also described in U.S. Patent Application No. 16 / 454,905, filed June 27, 2019, which is incorporated by reference in its entirety for purposes of describing markers that may be suitable for inclusion on a medical device. Each marker of the plurality of markers 78 may have any suitable configuration. As shown in FIG. 6, the circumferential markers may be disposed about the entire circumference of the body 72 of the elongate member 56 of the stylet 52. Alternatively, according to one embodiment, markers defining a portion of the circumference may be disposed about the body of a portion of the medical device (e.g., the elongate member of the stylet, the elongate member of the cannula) such that the marker extends about only a portion of the circumference of the body. Alternatively, the marker may include a structure that defines a curvature along a portion of the length of the elongate member, a structure that defines any suitable geometric shape (e.g., circle, polygon, rectangle) on a portion of the elongate member, a structure that defines a spiral along a portion of the length of the elongate member, or any combination thereof. The marker configurations described herein provide a mechanism for creating markers that produce image artifacts under MRI that are distinguishable from another medical device or combination of medical devices, surrounding fluids, and / or tissues imaged under MRI.

[0033] Although the elongate member 16 of the cannula 12 has been shown as including a tapered distal tip 42 having a cutting edge 44, and the elongate member 56 of the stylet 52 has been shown as including a tapered distal tip 74 having a cutting edge 76, the elongate members included in the medical device may include any suitable structural configuration, such as having a blunt or non-tapered distal tip. Additionally, in alternative embodiments, the hub member may include any suitable structure for effecting attachment to another device and / or may be omitted from the medical device, and / or the stylet may be hollow to define a lumen extending the entire length of the stylet or a portion of the length of the stylet.

[0034] The medical systems and / or devices described herein may be used with any suitable number of outer sheaths to perform a treatment. Selection of the appropriate number of outer sheaths to utilize, such as in completing the sequential expansion, may be based on the body passage in which the sequential expansion is to be completed. Examples of numbers of outer sheaths that may be suitable for utilization in completing the sequential expansion include one, two, multiple, three, four, five or more, and any other number that may be suitable for a particular embodiment.

[0035] 11 and 12 show an exemplary alternative medical device 100 that may be included in a medical system. In this example, the medical device 100 is an alternative embodiment of a stylet 102 that may be included in a medical system. The stylet 102 is similar to the stylet 50 illustrated in FIGS. 1, 3, 5, and 6 and described above, except as described in more detail below. In the illustrated embodiment, the stylet 102 has a hub member 104 and an elongate member 106. The elongate member 106 has a proximal end 108, a distal end 110, an outer surface 112, and a body 114 defining a solid member having a tapered distal tip 116 with a cutting edge 118.

[0036] The elongate member 106 includes a single marker 120 that extends along the entire length of the elongate member 106. In the illustrated embodiment, the marker 120 is formed as a single layer of material (e.g., metal, metal alloy) deposited along the outer surface 112 of the elongate member 106 to form a distinct marker visible under MRI. The elongate member 106 is formed of a third material and the marker 120 is formed of a fourth material. The third material has a third magnetic susceptibility and the fourth material has a fourth magnetic susceptibility that is different (e.g., greater than or less than) the third magnetic susceptibility. Although the marker 120 has been shown as extending along the entire length of the elongate member 106, the marker included in the elongate member may alternatively extend along a portion of the length of the elongate member.

[0037] 13 illustrates another exemplary alternative medical device 130 that may be included in a medical system. In this example, the medical device 130 is an alternative embodiment of a stylet 132 that may be included in a medical system. The stylet 132 is similar to the stylet 100 illustrated in FIGS. 11 and 12 and described above, except as described in more detail below. In the illustrated embodiment, the stylet 132 includes an elongate member 134 having an outer surface 136 and a body 138.

[0038] The elongate member 134 includes a first marker 140, a second marker 142, and a third marker 144. Each of the markers 140, 142, 144 extends along the entire length of the elongate member 134. The first marker 140 is formed as a first layer of material disposed on the exterior surface 136 of the elongate member 134, the second marker 142 is formed as a second layer of material disposed on the first marker 140, and the third marker 144 is formed as a third layer of material disposed on the second marker 142. In this embodiment, the markers 140, 142, 144 are disposed axially along a portion of the exterior surface 136 of the elongate member 134 as deposited layers of material to form distinct markers visible under MRI (e.g., along a portion of the axial length and / or at discrete points). Although each of the markers 140, 142, 144 has been shown as extending along the entire length of the elongate member 134, the markers included on the elongate member may alternatively extend along only a portion of the length of the elongate member.

[0039] The materials forming the first marker 140, the second marker 142, and the third marker 144 may include any suitable material having magnetic susceptibility as described herein. The material forming the first marker 140 may be the same as the material forming the second marker 142 and the material forming the third marker 144. Alternatively, the material forming the first marker 140 may be different from the material forming the second marker 142 and the material forming the third marker 144. Alternatively, the material forming the first marker 140 may be the same as the material forming the second marker 142 and different from the material forming the third marker 144. Alternatively, the material forming the first marker 140 may be different from the material forming the second marker 142 and the same as the material forming the third marker 144. Any suitable configuration of materials having magnetic susceptibility as described herein may be utilized to form distinct markers visible under MRI.

[0040] In the illustrated embodiment, the elongate member 134 is formed of a third material, the first marker 140 is formed of a fourth material, the second marker 142 is formed of a fifth material, and the sixth marker 144 is formed of a sixth material. The third material has a third magnetic susceptibility, the fourth material has a fourth magnetic susceptibility, the fifth material has a fifth magnetic susceptibility, and the sixth material has a sixth magnetic susceptibility. The fourth magnetic susceptibility is different (e.g., greater than or less than) the third magnetic susceptibility and different, greater than, less than, or equal to the fifth magnetic susceptibility and / or the sixth magnetic susceptibility. The fifth magnetic susceptibility is different (e.g., greater than or less than) the third magnetic susceptibility and different, greater than, less than, or equal to the fourth magnetic susceptibility and / or the sixth magnetic susceptibility. The sixth magnetic susceptibility is different from (eg, greater than or less than) the third magnetic susceptibility and different from, greater than, less than, or equal to the fourth magnetic susceptibility and / or the fifth magnetic susceptibility.

[0041] FIG. 14 illustrates another exemplary alternative medical device 150 that may be included in a medical system. In this example, the medical device 150 is an alternative embodiment stylet 152 that may be included in a medical system. The stylet 152 is similar to the stylet 100 illustrated in FIGS. 11 and 12 and described above, except as described in more detail below. In the illustrated embodiment, the stylet 152 includes an elongate member 154 having an outer diameter 155, an outer surface 156, an inner surface 158, and a body 160 that defines a lumen 162 that may extend through the entire length of the elongate member 154 or a portion of the length of the elongate member 154. A hub member included in the stylet similar to that shown in FIG. 11 may be included in the stylet 152 and may define a lumen that extends through the entire length of the hub member and provides access to the lumen 162 defined by the elongate member 154.

[0042] The elongate member 154 includes a first marker 164, a second marker 166, and a third marker 168. The first marker 164 extends along the entire circumference of the inner surface 158 of the elongate member 154, the second marker 166 extends along the entire circumference of the first marker 164, and the third marker 168 extends along the entire circumference of the second marker 166, with each of the markers 164, 166, 168 extending along some or all of the length of the elongate member 154. In the illustrated embodiment, the first marker 164 is formed as a first layer of material disposed on the inner surface 158 of the elongate member 154, the second marker 166 is formed as a second layer of material disposed on the first marker 164, and the third marker 168 is formed as a layer of material disposed on the second marker 166. Each of the markers 164, 166, 168 includes a deposited layer of material that forms a distinct marker visible under MRI.

[0043] The materials forming the first marker 164, the second marker 166, and the third marker 168 may include any suitable material having magnetic susceptibility as described herein. The material forming the first marker 164 may be the same as the material forming the second marker 166 and the material forming the third marker 168. Alternatively, the material forming the first marker 164 may be different from the material forming the second marker 166 and the material forming the third marker 168. Alternatively, the material forming the first marker 164 may be the same as the material forming the second marker 166 and different from the material forming the third marker 168. Alternatively, the material forming the first marker 164 may be different from the material forming the second marker 166 and the same as the material forming the third marker 168. Any suitable configuration of materials having magnetic susceptibility as described herein may be utilized to form distinct markers visible under MRI.

[0044] In the illustrated embodiment, the elongate member 154 is formed of a third material, the first marker 164 is formed of a fourth material, the second marker 166 is formed of a fifth material, and the sixth marker 168 is formed of a sixth material. The third material has a third magnetic susceptibility, the fourth material has a fourth magnetic susceptibility, the fifth material has a fifth magnetic susceptibility, and the sixth material has a sixth magnetic susceptibility. The fourth magnetic susceptibility is different (e.g., greater than or less than) the third magnetic susceptibility and different, greater than, less than, or equal to the fifth magnetic susceptibility and / or the sixth magnetic susceptibility. The fifth magnetic susceptibility is different (e.g., greater than or less than) the third magnetic susceptibility and different, greater than, less than, or equal to the fourth magnetic susceptibility and / or the sixth magnetic susceptibility. The sixth magnetic susceptibility is different from (eg, greater than or less than) the third magnetic susceptibility and different from, greater than, less than, or equal to the fourth magnetic susceptibility and / or the fifth magnetic susceptibility.

[0045] Although markers 164, 166, and 168 are shown as multiple layers, a single marker may be utilized and disposed on the interior surface of the medical device and along all or a portion of the circumference and / or length of the medical device. In embodiments where the materials are disposed in layers and different materials are used for each layer, these structural configurations may be used to take advantage of the effect that each material collectively has in distorting an external magnetic field (e.g., causing image artifacts) when the medical device in which the materials are disposed is visualized under an MRI, allowing for adjustable image artifacts anywhere on the device.

[0046] 15 illustrates another exemplary alternative medical device 170 that may be included in the medical system. In this example, the sixth medical device 170 is an alternative embodiment stylet 172 that may be included in the medical system. The stylet 172 is similar to the stylet 10 illustrated in FIGS. 1, 3, 5, and 6 and described above, except as described in more detail below. In the illustrated embodiment, the stylet 172 has a hub member 174 and an elongate member 176. The elongate member 176 has a proximal end 178, a distal end 180, an outer surface 182, and a body 184 defining a solid member having a tapered distal tip 186 with a cutting edge 188.

[0047] The elongate member 176 comprises a first portion 190, a second portion 192, a third portion 194, a fourth portion 196, and a fifth portion 198. The first portion 190 extends from the proximal end 178 of the elongate member 176 to the second portion 192. The second portion 192 extends from the first portion 190 to the third portion 194. The third portion 194 extends from the second portion 192 to the fourth portion 196. The fourth portion 196 extends from the third portion 194 to the fifth portion 198. The fifth portion 198 extends from the fourth portion 196 to the distal end 180 of the elongate member 176.

[0048] First portion 190 is formed of a first material, second portion 192 is formed of a second material, third portion 194 is formed of a third material, fourth portion 196 is formed of a fourth material, and fifth portion 198 is formed of a fifth material. Any suitable material having a magnetic susceptibility as described herein may be used to form each portion of elongate member 176 (e.g., metal, polymer). For example, the materials forming portions 190, 192, 194, 196, 198 may be the same or different from one another (e.g., may have different material properties). In embodiments in which portions 190, 192, 194, 196, 198 are formed of one or more distinct materials, each portion may be joined to adjacent portions using any suitable method or technique (e.g., welding, fusing, using adhesives). Alternatively, a first set of portions 190, 192, 194, 196, 198 of elongate member 176 may be formed of the same material, and a second set of portions 190, 192, 194, 196, 198 of elongate member 176 may be formed of a different material. In embodiments in which portions 190, 192, 194, 196, 198 are formed of the same material, one or more portions of elongate member 176, or the material forming each portion, may be locally altered (e.g., work hardened, tempered) to change its magnetic properties. If portions 190, 192, 194, 196, 198 are formed of more than one material (e.g., formed of different materials) or are formed of the same material but with different magnetic susceptibilities or relative susceptibilities, at least one portion may have a magnetic susceptibility that distorts external magnetic fields and creates image artifacts. In these embodiments, the materials forming portions 190, 192, 194, 196, 198 may be selected such that their influence, either independently or collectively, acts on an external magnetic field to produce image artifacts under MRI, which may be accomplished by forming one or more of portions 190, 192, 194, 196, 198 as markers having magnetic susceptibility as described herein.

[0049] 16, 17, and 18 illustrate another exemplary alternative medical device 200 that may be included in a medical system. In this example, the medical device 200 is an alternative embodiment of a stylet 202 that may be included in a medical system. The stylet 202 is similar to the stylet 50 illustrated in FIGS. 1, 3, 5, and 6 and described above, except as described in more detail below. In the illustrated embodiment, the stylet 202 has an elongate member 204 having an outer surface 206, an inner surface 208, and a body 210 defining a lumen 212 that may extend through the entire length of the elongate member 204 or a portion of the length of the elongate member 204.

[0050] The body 210 of the stylet 202 defines a wall 214 having an outer surface 206 and an inner surface 208. A wall thickness extends between the outer surface 206 and the inner surface 208. The body 210 of the stylet 202 defines a passageway 216 that extends from the inner surface 208 to the outer surface 206, all through the thickness of the wall 214. Alternatively, the recess may extend partially through only a portion of the wall thickness, from the inner surface to the outer surface, or from the outer surface to the inner surface. The passageway and / or recess included in the medical device may have any suitable dimensions and may be located in any suitable location on the medical device. Examples of diameters that may be suitable for the passageway and / or recess include diameters equal to, greater than, or less than about 0.010 inches, 0.018 inches, 0.025 inches, diameters between about 0.010 inches and about 0.025 inches, and any other diameters that may be suitable for a particular embodiment.

[0051] In the illustrated embodiment, the elongate member 204 of the stylet 202 includes a single marker 218, which is a plug 220 disposed within the passageway 216. The plug 220 has a body 222, which is a solid member that blocks access to the lumen 212 defined by the stylet 202. However, alternative embodiments may include two or more markers and / or plugs that define a passageway extending through the plug. The marker 218 is flush with the inner surface 208 and the outer surface 206, and in the illustrated embodiment, is press fit into the passageway 216. Additional fastening measures may be used as desired. For example, the marker may be laser welded to the wall of the stylet to secure the marker to the passageway. The plug 220 may have any suitable diameter and shape, which may be based on the diameter of the passageway in which the plug is intended to be placed. Examples of plug diameters that may be suitable for inclusion in the medical device include diameters less than or equal to about 0.010 inches, 0.018 inches, 0.025 inches, diameters between about 0.010 inches and about 0.025 inches, and any other diameters that may be suitable for a particular embodiment.

[0052] The passages and / or recesses can be formed in the medical device using any suitable technique or method, such as laser drilling, electrical discharge machining (EDM), grinding, stamping, micro-drilling, etc. The markers included in the medical device can be attached to the medical device using any suitable technique or method. Examples of techniques and methods that may be suitable for attaching the markers to the medical device include pressing, welding, using adhesives, and any other techniques and methods that may be suitable for a particular embodiment. For example, while the material forming the medical device is in a base form (e.g., the elongate member is in the form of a ribbon), the markers can be inserted and attached to the material intended to form the medical device or a portion of the medical device (e.g., the elongate member of the medical device). The base material (e.g., ribbon) containing the markers can then be formed into the medical device or a portion of the medical device (e.g., the elongate member) using any suitable method or technique (e.g., welding or drawing the material).

[0053] In the illustrated embodiment, as shown in Figures 16, 17, and 18, the marker 218 (e.g., plug 220) includes magnetically susceptible particles 224 (e.g., magnetically susceptible metal particles) dispersed within a bulk material 226 (e.g., epoxy resin). The elongate member 204 is formed of a third material having a third magnetic susceptibility, the magnetically susceptible particles 224 are formed of a fourth material having a fourth magnetic susceptibility, and the bulk material 226 is formed of a fifth material having a fifth magnetic susceptibility. The fourth magnetic susceptibility is different from, equal to, less than, or greater than the third magnetic susceptibility. The fifth magnetic susceptibility is different from (e.g., greater than or less than) the third magnetic susceptibility and different from, equal to, less than, or greater than the fourth magnetic susceptibility.

[0054] The magnetically susceptible particles 224 may be used to distort the magnetic field used during MRI to produce adjustable image artifacts in the resulting image. However, alternative embodiments may include plugs formed of magnetically susceptible metal. Forming the markers 218 of the magnetically susceptible particles 224 results in the medical device 200 with passive markers that may be seen when creating MR images using MRI. The markers 218 have properties that produce visual image artifacts during an MRI procedure in which the medical device 200 is imaged. These visual image artifacts may be used to determine the placement of the medical device 200 relative to other parts of the image created under MRI, such as the part of the body passageway into which the medical device 200 is inserted and / or another medical device.

[0055] The magnetically susceptible particles 224 included in the plug may include any suitable type and size of magnetically susceptible metal particles having a magnetic susceptibility as described herein. Examples of magnetically susceptible particles (e.g., magnetically susceptible metal particles) that may be suitable for inclusion in the plug include MRI compatible materials, stainless steel, hardened forms of stainless steel, ferritic stainless steel (e.g., 400 series such as 430L), stainless steel martensitic alloys (e.g., 316L, 304, 304L), nickel alloys such as those used in magnetic shielding (e.g., AD-MU-80, Mumetal), materials described herein, and any other materials that may be suitable for a particular embodiment. Figures 19, 20, and 21 show various materials that may be used to create a plug for inclusion in the medical devices described herein.

[0056] Although the magnetically susceptible particles 224 have been shown as being dispersed in a bulk material 226, the magnetically susceptible particles of the marker may be dispersed in any suitable MRI compatible material, such as those described herein. In addition, other susceptible materials that may be used to disperse the magnetically susceptible particles or to include the magnetically susceptible particles in a dispersion include polymers, thermoplastic polymers (such as nylon, Pebax, polyolefin, PEEL, FEP, or TFE), photopolymers, glass, ceramic microspheres, ceramic nanospheres, adhesive binders, MR inert materials, materials described herein, and any other materials deemed suitable for a particular embodiment. These materials may be added to improve the uniform distribution of the susceptible particles within a given volume and / or to aid in the processability and manufacturability of the marker without directly affecting the resulting image artifacts.

[0057] The use of plugs containing magnetically susceptible particles (e.g., metal particles) dispersed in a magnetically unsusceptible material (e.g., epoxy resin) or having a magnetic susceptibility different from (e.g., less than) that of the magnetically susceptible particles is believed to be advantageous, at least because testing in imaging phantoms and tissue samples has demonstrated excellent marker visibility in multiple MR field strengths, imaging sequences, and machines, and may be used to produce adjustable susceptibility-based image artifacts under MR imaging. For example, these markers are adjustable, repositionable, and easy to manufacture. The presence and manipulation of susceptibility markers along the shaft of an interventional device may enhance the safety, effectiveness, and efficiency of interventional MRI procedures.

[0058] Although the markers 218 have been shown as being disposed within a passageway defined by an elongate member of the medical device, alternative embodiments may place the magnetically non-susceptible material (e.g., epoxy resin) or the magnetically susceptible particles (e.g., metal particles) dispersed in a material having a magnetic susceptibility different from (e.g., less than) that of the magnetically susceptible particles within recesses or other features defined by the medical device (e.g., on an interior or exterior surface of the medical device). The recesses or other features of the medical device may be created in the medical device using any suitable technique or method, such as EDM, micromachining, laser machining, grinding, and / or stamping.

[0059] The plugs included in medical devices such as those described herein may be formed by potting the particles using a two-part epoxy resin (e.g., medical grade epoxy resin, Loctite EA M-31CL) or any other suitable technique or method. Any suitable concentration of magnetically susceptible particles (e.g., metal particles) may be used relative to the material in which the magnetically susceptible particles are dispersed. For example, the concentration may range between about 3 parts by weight of magnetically susceptible particles for about 1 part by weight of a magnetically insensitive material (e.g., epoxy resin) or material having a magnetic susceptibility different from (e.g., less than) that of the magnetically susceptible particles, and about 1 part by weight of magnetically susceptible particles for about 4 parts by weight of a magnetically insensitive material (e.g., epoxy resin) or material having a magnetic susceptibility different from (e.g., less than) that of the magnetically susceptible particles. Alternatively, the magnetically susceptible particles contained in the marker may comprise a concentration of a fractional weight percent (e.g., about 0.01% to about 0.99%) to several weight percentage points (e.g., 5%) relative to a material that is not magnetically susceptible (e.g., epoxy resin) or to a material that has a magnetic susceptibility different from (e.g., smaller than) that of the magnetically susceptible particles.

[0060] In an alternative embodiment, a solid piece of material described as forming the magnetically susceptible particles can be cut and used as a plug and attached to the elongate member of the medical device described herein. Alternatively, a solid piece of material (e.g., 0.002 inch thick AD-MU-80) can be die cut to a diameter slightly smaller than the diameter of the passageway in which it is intended to be placed. The solid piece of material can then be glued into the passageway defined by the elongate member of the medical device using a bulk material combination of the magnetically susceptible particles described herein or other materials.

[0061] As described herein, the placement of the markers relative to the medical device may vary. However, it is believed to be advantageous to place the markers such that each image artifact produced under MRI is clearly distinguishable from other image artifacts (e.g., with a gap of about 1.5 centimeters between the boundaries of the produced artifacts). Optionally, the markers may be placed in a specific pattern to aid in identifying and orienting the medical device during use.

[0062] Figures 22, 23, and 24 show marker plugs of various diameters and materials cast separately from the medical device. Figures 23 and 24 show these plugs imaged under a magnetic field strength of 3.0T. These figures show the effect of dispersing magnetically susceptible metal particles in epoxy resin and measure the size of the artifacts. As shown, distinguishable marker artifacts are demonstrated under multiple imaging modalities including spin echo (SE) and gradient refocusing echo (GRE) sequences. In addition, distinguishable marker artifacts are also demonstrated under other magnetic field strengths (e.g., 0.5T, 1.5T) and imaging modalities such as high frame rate functional imaging sequences, true high speed imaging with steady state precession (TrueFisp), and high speed low flip angle shot (FLAS) spoiled gradient echo.

[0063] Optionally, markers such as those described herein (e.g., plugs) may be sealed (e.g., within a recess or passageway in which they are located) to enhance biocompatibility, safety, and / or ease of use. For example, an overcoating of a magnetically resistant material, such as a magnetically resistant metallic material (e.g., gold, silver, or other alloys), an inert material, and / or a non-metallic material (e.g., fluoropolymer, ceramic alumina), may be deposited, laminated, or disposed over a portion of the medical device including the marker (e.g., plug) or over the entire medical device. Such an overcoating may be accomplished using any suitable technique or method, such as electroplating, sputtering, or vapor deposition.

[0064] In alternative embodiments, materials may be compounded with magnetically susceptible particles (e.g., metal particles) and inserted or injection molded into passages or recesses defined by the medical device. For example, magnetically susceptible particles such as those described herein and / or non-susceptible particles used as fillers may be dispersed in a non-epoxy material (e.g., a magnetically non-susceptible material, a material having a magnetic susceptibility different from (e.g., less than) that of the material forming the magnetically susceptible particles, an adhesive binder). This may be accomplished by particle sintering and / or doping the magnetically susceptible particles (e.g., metal particles) and / or non-susceptible particles into a base material (e.g., a polymer) that may be utilized to create the marker. Markers created using these materials may be used to create any suitable type of structure and / or marker (e.g., bands, curves, stripes, coverings, plugs, coatings, extruded solids, elongated members, elongated members defining lumens, molded components), such as those described herein. Creating structures and / or markers using these materials is believed to be advantageous at least because it allows for selectively enhancing the visibility of at least a portion of the interventional device and / or introducing features that are easily identifiable under MRI guidance by producing an adjustable susceptibility artifact.

[0065] For example, in one alternative embodiment, at least a portion of a medical device (e.g., a solid polymeric stylet) can be doped with magnetically susceptible particles or solids to highlight the tip of the medical device (e.g., a stylet) or other portions of the elongate member of the medical device (e.g., a stylet). In another alternative embodiment, a solid body or portion of a multi-layer polymeric medical device (e.g., a catheter) can be loaded with magnetically susceptible particles or solids to generate artifacts at the tip of the medical device, at predetermined bends along the elongate member of the medical device, and / or where bends are to be formed during use. In any of these alternative embodiments, the magnetically susceptible particles or solids need not be directly incorporated into the primary structure (e.g., polymer) of the device. Instead, a polymer loaded or incorporated with magnetically susceptible particles may be separately cast or molded into a separate marker structure as described herein and incorporated into the device during manufacture. Alternatively, in embodiments where the magnetically susceptible material is compounded into a base material (e.g., a material having a magnetic susceptibility less than that of the material forming the magnetically susceptible particles), the base material may be utilized in any suitable manufacturing process to form the medical device (such as modern 3D printing processes, fused deposition modeling, stereolithography additive printing, and / or selective laser sintering). Thus, the magnetically susceptible particles or solids may be compounded into a polymer and extruded into filaments, dispersed in a photopolymer, or mixed with a base polymer in a ground state for sintering. At least one portion or feature of the interventional medical device may then be constructed from additional layers of any of these composite polymers to render at least one portion or feature of the device visible under MRI. For example, the magnetically susceptible dispersion may be used to construct the entire medical device (e.g., a solid or hollow shaft) or at least one selected feature of the medical device (e.g., a covering, coating, jacket, marker band or segment, molded component).Alternatively, the construct can be an extruded tube where co-extrusion or intermittent extrusion can be used to encapsulate the entire magnetically susceptible material (eg, a magnetically susceptible metal-doped substrate).

[0066] 25 illustrates an exemplary alternative medical device 240 that may be included in a medical system. In this example, the medical device 240 is an alternative embodiment of a cannula 242 that may be included in a medical system. The medical device 240 includes a first portion 242 formed as an outer lubricious layer, a second portion 244 formed as an intermediate layer, and a third portion 246 formed as an inner layer. The first portion 242 is formed of a first material, the second portion 244 is formed of a second material, and the third portion 246 is formed of a third material. The first material is different from the second and third materials and has a first magnetic susceptibility. The second material (e.g., such as those described herein (e.g., a dispersion material of magnetically susceptible particles (e.g., metal particles) dispersed in a material different from the material forming the magnetically susceptible particles) is distinct from the first material and the third material and has a second magnetic susceptibility different from (e.g., greater than or less than) the first magnetic susceptibility. The third material is distinct from the first material and the second material and has a third magnetic susceptibility different from (e.g., greater than or less than) the second magnetic susceptibility and different from, equal to, less than, or greater than the first magnetic susceptibility. For example, the first material can be a polymer, the second material can be a PFTE including magnetically susceptible particles (e.g., stainless steel powder), and the third material can be a polymer.

[0067] As described herein, visualization of devices during the performance of procedures (e.g., treatment) is a fundamental challenge in interventional MRI. Conventional interventional devices and materials are either highly susceptible, resulting in artifacts that wash out key features of the imaged tissue / magnetic field, or are minimally susceptible, leaving the device invisible for identification or tracking in the image. Thus, there is a need to directly leverage diagnostic imaging modalities, particularly MR, to guide treatment. Identification and precise targeting of lesions or abnormal anatomical structures is a clinically significant challenge. The medical devices described herein are believed to be advantageous because, at a minimum, they substantially improve the clinician's ability to accurately visualize, identify, track, and navigate to various locations within the body, and can improve overall patient care (e.g., diagnosis, treatment delivery) by highly accurate positioning of markers along the longitudinal axis of the medical device. The markers described herein can be used in conjunction with medical devices to generate identifiable patterns in interventional MR images, allowing for advanced control over the location, size, and intensity of susceptibility artifacts caused by the interventional devices. FIG. 26 illustrates a set of exemplary alternative medical devices 250, 251 that may be included separately or in combination in a medical system. In this example, each of the medical devices 250, 251 is an alternative embodiment of a stylet 252 that may be included in a medical system such as that described herein. The stylets 252 are similar to the stylets 50 illustrated in FIGS. 1, 3, 5, and 6 and described above, except as described in more detail below. In the illustrated embodiment, each stylet 252 has a hub member 254 and an elongate member 256. The elongate member 256 has a proximal end 258, a distal end 260, an outer surface 262, and a body 264 that defines a distal tip 266.

[0068] The elongate member 256 includes a plurality of markers 270 (e.g., four markers) disposed between the proximal end 258 and the distal end 260 of the elongate member 256. In the illustrated embodiment, each marker of the plurality of markers 270 is formed as a single layer of material (e.g., metal, metal alloy) deposited on the outer surface 262 of the elongate member 256 to form a distinct marker visible under MRI. Each marker of the plurality of markers 270 is a marker band disposed around the entire circumference of the outer surface 262 of the elongate member 256. However, alternative embodiments can include markers that extend only partially around the circumference of the outer surface of the elongate member and markers having any suitable structural configuration, such as those described herein.

[0069] The material deposited on the medical device to form the marker may be deposited to form any suitable shape having any suitable size and formed of any suitable material having the magnetic susceptibility described herein. For example, when a marker (e.g., a marker band) is formed using a material deposited on a portion of a medical device, the marker may have any suitable width (e.g., a width equal to or less than about 0.6 millimeters, 1.2 millimeters or greater) along the longitudinal axis of the medical device (e.g., an elongated member of the medical device) and any suitable thickness (e.g., equal to or less than about 0.0006 inches) measured along a cross-section of the medical device (e.g., an elongated member of the medical device). Optionally, multiple layers of material (e.g., two or more layers of the same or different materials) may be used to make the marker. In the illustrated embodiment, the first medical device 250 includes a marker having a width equal to approximately 0.6 millimeters and the second medical device 251 includes a marker having a width equal to approximately 1.2 millimeters.

[0070] In the illustrated embodiment, each marker of the plurality of markers 270 is formed of nickel, which is plated onto a portion of the elongate member 256 using a nickel strike electroplating process having a thickness equal to approximately 0.0006 inches to deposit a thin layer of nickel onto the portion of the elongate member 256. Examples of materials that may be suitable for depositing onto a medical device to form a marker include nickel plating (e.g., bright nickel plating), materials described herein and having the magnetic susceptibility described herein, and any other material according to an embodiment.

[0071] Placing the material on the medical device (e.g., plating) may be accomplished using any suitable technique or method, such as electroplating, sputtering, striking, vapor deposition, chemical vapor deposition, coating, chemical baths, evaporation techniques, and any other technique or method deemed suitable for a particular embodiment. Optionally, the material may be placed on the medical device such that the areas where the markers are desired remain exposed after masking the medical device. Examples of suitable types of masking include heat shrink tubing, taping, spray or dip coating, photoresist, and / or molds (e.g., silicone molds) that inhibit deposition of the base material on the surface. For example, heat shrink tubing (e.g., fluoropolymer heat shrink tubing) may be used to selectively mask off segments of the medical device (e.g., elongated member), leaving portions of the medical device exposed for plating (e.g., 0.06 millimeter portions, 1.2 millimeter portions). In another example, a reusable silicone mold may be used to hold and mask off the medical device or portions of multiple devices simultaneously. After masking, the exposed portions of the medical device can optionally be cleaned and plated (e.g., using Wood's nickel strike process, which can be used to promote adhesion of successive layers of electroplated nickel). Another example includes applying a masking material (e.g., a polymer) to the entire medical device or to a portion of the medical device, and then creating a distinct marker on the medical device (e.g., using laser ablation to create a distinct marker). Any molds used to create the markers can be removed prior to using the device in a clinical setting.

[0072] Instead of masking portions of the medical device, a thin layer of magnetically susceptible material can be applied to portions or the entire medical device, and excess material can be removed (e.g., during post-processing) to form distinct markers. Subtractive processes that may be suitable for forming markers in this manner include sanding, grinding, etching, and any other technique or method that may be suitable for a particular embodiment.

[0073] These embodiments are believed to be advantageous at least because they are easily manufacturable, scalable, do not change the mechanical properties of the medical device (e.g., 3-point bending, tensile strength, column strength), and have minimal effect on the surface profile of the device. Additionally, these embodiments are believed to be advantageous at least because the deposited thin film of material allows for a high degree of control over marker size and shape, and can be masked using overplating to prevent delamination and improve biocompatibility.

[0074] 27-30 show test results associated with medical device 250 and medical device 251. Both medical devices 250, 251 have been tested in imaging phantom material (e.g., copper sulfate solution) and porcine tissue at MRI magnetic field strengths of 0.55 T, 1.5 T, and 3.0 T. Any suitable type of imaging sequence for observing markers under MRI can be used, such as gradient refocusing echo, spin echo, true high speed imaging with steady state precession, high speed low flip angle shot spoiled gradient echo, and any other functional imaging sequence.

[0075] As shown in Figures 27-30, a first medical device 250 has a first pattern of markers 273 and a second medical device has a second pattern of markers 275. The markers included on the first and second medical devices 250, 251 produce a repeatable and adjustable image artifact 271 that can be used to visualize, track, and navigate the medical devices during interventional MR procedures. During these procedures, image processing software or machine learning can optionally be used to determine the status of these markers in near real-time, aiding in the estimation of device placement with automated sequence selection and enabling path planning to the target location while avoiding critical or sensitive anatomical structures during treatment delivery.

[0076] Although the medical devices described herein include cannulas and stylets, the markers described herein may be included in any suitable medical device, and the selection of an appropriate medical device to include a marker in may be based on a variety of considerations, including the intended use of the medical device in which the marker is placed. Examples of medical devices that may be suitable for including a marker include cannulas, needles, stylets, sheaths, catheters, balloon catheters, guidewires, introducers, implantable devices, and any other medical device that may be suitable for a particular embodiment.

[0077] FIG. 31 illustrates a first medical device 302 according to an embodiment, such as the first medical device 10 shown in FIGS. 1 and 2; a second medical device 304 according to an embodiment, such as the second medical device 50 shown in FIGS. 1, 3, 5, and 6; a third medical device 306 according to an embodiment, such as the medical device 100 shown in FIG. 11; a fourth medical device 308 according to an embodiment, such as the medical device 130 shown in FIG. 13; a fifth medical device 310 according to an embodiment, such as the medical device 150 shown in FIG. 14; 20 shows an exemplary kit 300 including a sixth medical device 312 according to an embodiment, such as medical device 170, a seventh medical device 314 according to an embodiment, such as medical device 200 shown in FIGS. 16, 17, and 18, an eighth medical device 316 according to an embodiment, such as medical device 240 shown in FIG. 25, a ninth medical device 318 according to an embodiment, such as medical device 250 shown in FIG. 26, a tenth medical device 320 according to an embodiment, such as medical device 251 shown in FIG. 26, and methods of use 322.

[0078] Although the kit 300 has been shown as including ten medical devices 302, 304, 306, 308, 310, 312, 314, 316, 318, and 320, any suitable number and type of medical devices may be included in the kit. Selection of the appropriate number of medical devices to include in the kit according to certain embodiments may be based on various considerations, such as the treatment intended to be performed. Examples of numbers of medical devices that may be suitable for inclusion in the kit include at least one, one, two, multiple, three, four, five, six, seven, eight, nine, ten, eleven or more, and any other number that may be suitable for a particular embodiment. In alternative embodiments, the kit may include one or more medical systems, such as those described herein, and may include any suitable number and type of medical devices, such as those described herein.

[0079] Additionally, although medical device 10, medical device 50, medical device 100, medical device 130, medical device 150, medical device 170, medical device 200, medical device 240, medical device 250, and medical device 251 have been shown as being included in kit 300, any suitable medical device may be included in the kit. Selection of suitable medical devices to include in a kit according to a particular embodiment may be based on a variety of considerations, such as the treatment intended to be performed. Examples of medical devices that may be suitable for inclusion in a kit include those described herein, variations of those described herein, one or more inner sheaths, one or more outer sheaths, one or more access needles, and / or any other medical device that may be suitable for a particular embodiment.

[0080] The inclusion of medical devices in kits as described herein is believed to be advantageous because, at least in some alternative kit embodiments, a single needle (e.g., medical device 10) may be packaged with multiple secondary medical devices (e.g., stylets) and the needle may be used independently or simultaneously with each of the secondary medical devices, each of which may be used under MRI using multiple MR field strengths or may be specifically tailored to accommodate multiple MR-guided interventional procedures (e.g., treatments).

[0081] For example, in an embodiment in which the kit includes multiple medical devices (e.g., a needle and multiple stylets), a first medical device (e.g., a stylet) may include a material (e.g., a marker) that is adjusted for (e.g., visible under) a first MR magnetic field strength (e.g., 0.55T), a second medical device (e.g., a stylet) may include a material (e.g., a marker) that is adjusted for (e.g., visible under) a second MR magnetic field strength (e.g., 1.5T), and a third medical device (e.g., a stylet) may include a material (e.g., a marker) that is adjusted for (e.g., visible under) a third MR magnetic field strength (e.g., 3T). The first MR magnetic field strength may be different or the same as the second MR magnetic field strength and / or the third MR magnetic field strength. The second MR magnetic field strength may be different or the same as the first MR magnetic field strength and / or the third MR magnetic field strength. The third MR magnetic field strength may be different or the same as the first MR magnetic field strength and / or the second MR magnetic field strength. This embodiment may be accomplished using materials (e.g., metals, metal alloys, materials described herein) having a target magnetic susceptibility, a geometric size disposed along a portion of the medical device (e.g., the length of an elongated member of the medical device). For example, the first medical device may have a first type of marker and a first magnetic susceptibility, the second medical device may have a second type of marker and a second magnetic susceptibility, and the third medical device may have a third type of marker and a third magnetic susceptibility. The first type of marker may be the same or different from the second type of marker and / or the third type of marker. The first magnetic susceptibility or first susceptibility may be the same or different (e.g., greater or lesser) than the second magnetic susceptibility or second susceptibility, and / or the third magnetic susceptibility or third susceptibility. The second type of marker may be the same as or different from the first type of marker and / or the third type of marker. The second magnetic susceptibility or second susceptibility may be the same as or different from (e.g., greater than or less than) the first magnetic susceptibility or first susceptibility and / or the third magnetic susceptibility or third susceptibility.The third type of marker may be the same or different from the first type of marker and / or the second type of marker. The third susceptibility or third susceptibility may be the same or different (e.g., greater or less) than the first susceptibility or first susceptibility and / or the second susceptibility or second susceptibility. Alternatively, a medical device such as that described herein (e.g., a stylet) may be equipped with markers covering a range of different interventional MRI procedures under single or multiple magnetic field strengths and may be included in a kit with a second MRI compatible medical device (e.g., a needle). In a specific embodiment, a single titanium needle may be packaged with multiple stylets, each of which may be used independently or simultaneously, depending on the MRI static magnetic field strength intended to be used or the particular interventional procedure intended to be completed. Alternatively, the markers included in the medical device may be tailored to a particular MR sequence.

[0082] In one example, a kit useful in performing a treatment under magnetic resonance comprises a first medical device of an embodiment, a second medical device of an embodiment, and a third medical device of an embodiment. The first medical device comprises a first marker that produces a first image artifact under a first MR magnetic field strength. The second medical device comprises a second marker that produces a second image artifact under a second MR magnetic field strength. The third medical device comprises a third marker that produces a third image artifact under a third MR magnetic field strength. The first MR magnetic field strength is different from the second MR magnetic field strength and the third MR magnetic field strength. The second MR magnetic field strength is different from the third MR magnetic field strength. The first image artifact has a first set of characteristics (e.g., size, shape, pattern, and / or strength) under the first MR magnetic field strength, a second set of characteristics under the second MR magnetic field strength, and a third set of characteristics under the third MR magnetic field strength. The first set of characteristics of the first image artifact is different from the second set of characteristics of the first image artifact and the third set of characteristics of the first image artifact. The second set of characteristics of the first image artifact is different from the third set of characteristics of the first image artifact. The second image artifact has a first set of characteristics under a first MR magnetic field strength, a second set of characteristics under a second MR magnetic field strength, and a third set of characteristics under a third MR magnetic field strength. The first set of characteristics of the second image artifact is different from the second set of characteristics of the second image artifact and the third set of characteristics of the second image artifact. The second set of characteristics of the second image artifact is different from the third set of characteristics of the second image artifact. The third image artifact has a first set of characteristics under a first MR magnetic field strength, a second set of characteristics under a second MR magnetic field strength, and a third set of characteristics under a third MR magnetic field strength. The first set of characteristics of the third image artifact is different from the second set of characteristics of the third image artifact and the third set of characteristics of the third image artifact. The second set of characteristics of the third image artifact is different from the third set of characteristics of the third image artifact.

[0083] The kits described herein advantageously provide clinicians with a single product (e.g., a kit) that can be used under multiple settings. A titanium needle with low magnetic susceptibility allows precision of positioning near the tip where treatment is performed (e.g., where a biopsy is performed), while markers on one or more removable stylets allow real-time trackability at any magnetic field strength or across multiple interventional procedures. Although the present exemplary embodiment describes the use of a needle and multiple stylets, such an embodiment may include any suitable combination of medical devices such as those described herein (e.g., sheath, removable dilator). For example, a sheath with low magnetic susceptibility (e.g., producing small image artifacts under MRI) may be packaged with multiple removable dilators, each containing one or more markers (e.g., different magnetic susceptibility, a relatively high magnetic susceptibility producing large image artifacts under MRI) to facilitate use under various MRI static magnetic field strengths.

[0084] Various methods of performing MRI-guided interventional procedures are described herein. Although the methods described herein are illustrated and described as a series of acts, it is to be understood and appreciated that the methods are not limited by the order of acts, as some acts of the methods may be omitted, performed in the order shown and / or described, performed in a different order, and / or performed prior to, following, or concurrently with other acts described herein.

[0085] FIG. 32 shows a schematic diagram of an exemplary method 400 for performing therapy under MRI.

[0086] A first step 402 includes positioning the patient in the MR scanner. Another step 404 includes scanning a first portion of the patient using the MR scanner. Another step 406 includes acquiring an MR image of the first portion of the patient. Another step 408 includes identifying tissue with predefined characteristics using the MR image. Another step 410 includes selecting a procedure for treating the tissue based on the predefined characteristics. Another step 412 includes selecting an MR sequence and / or parameters to use during the execution of the selected procedure. Another step 414 includes selecting a medical device to perform the execution of the medical procedure based on the selected MR sequence and / or parameters intended to be used during the execution of the selected procedure. While the patient is still positioned in the MR scanner used to scan a portion of the patient, another step 416 includes inserting the medical device into the body passage and up to the tissue while scanning a second portion of the patient including the medical device using the MR scanner. Another step 418 includes acquiring an MR image of the second portion of the patient including the medical device. Another step 420 includes verifying the position of the medical device in the body passage. Another step 422 includes administering a treatment using the medical device.

[0087] Step 402 may be performed by placing the patient in any suitable MR scanner having any suitable magnetic field strength (such as a conventional MR scanner, an MR scanner capable of performing gradient refocusing echo imaging, an MR scanner capable of performing spin echo imaging, an MR scanner capable of performing true high speed imaging with steady state precession, an MR scanner capable of performing high speed low flip angle shot spoiled gradient echo imaging, an MR scanner utilizing a magnetic field of 0.55T, a magnetic field of 1.5T, a magnetic field of 3T, a magnetic field between about 0.055T and 1.5T, a magnetic field less than 1T, and any other MR scanner deemed suitable for the particular embodiment).

[0088] Step 404 may be accomplished by scanning any suitable portion of the patient, and selection of the appropriate portion of the patient to scan may be based on a variety of considerations, including the treatment intended to be performed. Examples of portions of the patient that may be suitable for scanning include the extremities (e.g., arms, legs), chest, breasts, spine, neck, head, abdomen, pelvis, prostate, perifrostatic structures, tissue surrounding the portions of the patient described herein, and / or any other portion of the patient that may be suitable for a particular embodiment.

[0089] Step 406 may be performed by acquiring an MR image from the magnetic resonance scanner used in step 402 .

[0090] Step 408 may be accomplished by reviewing the MR images acquired in step 406 and utilizing conventional techniques and / or methods to determine whether the tissue has predefined characteristics (e.g., the tissue has characteristics indicative of cancer, is a lesion, is an abnormal mass), etc. Additionally, margins of any tissue (e.g., an abnormal mass) may be identified and used in further steps to remove and / or treat the tissue, as described herein.

[0091] Step 410 may be performed by reviewing the predefined characteristics identified in step 408 and selecting a procedure for treating the tissue based on the predefined characteristics.

[0092] Step 412 may be performed based on the procedure selected in step 410, the available MR scanner, and / or the utilization of any suitable number and / or type of sequences and / or parameters. The MR scanner may have any suitable number and type of MR imaging parameters (such as gradient refocusing echo imaging, spin echo imaging, true high speed imaging with steady state precession, high speed 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 less than 1T, slice thickness, flip angle, field of view, resolution, gradient fields, and any other imaging parameters deemed suitable for a particular embodiment). The MR scanner may have any suitable number and type of MRI sequence parameters (SE / GRE, TR, TE, flip angle, field of view, resolution, slice thickness, gradient fields). Optionally, the MR sequences and / or parameters may be modified throughout the execution of the procedure to adapt the medical system and / or medical device.

[0093] Step 414 may be performed using one or more of the medical devices described herein, the medical systems described herein, or any other suitable medical devices or systems. Alternatively, the medical device or system may be selected from a kit, such as kit 300, and the selection of the medical device or system may be based on the MR magnetic field selected in step 412.

[0094] Step 416 may be performed using the medical device selected in step 414. Alternatively, step 416 may be performed using any suitable medical device or medical system, such as the medical devices incorporated herein by reference. Examples of medical devices that may be suitable for use to complete the method of treatment, and other steps that may be suitable for inclusion in the method of treatment, are described in U.S. Patent Application No. 17 / 573,087, filed January 11, 2022, which is incorporated herein by reference in its entirety for purposes of describing medical devices that may be suitable for completing the method of treatment, and for purposes of describing steps that may be suitable for inclusion in the method of treatment. Step 416 may be performed by applying a distally directed force to the medical device such that the distal end of the medical device is inserted into the body passageway and into, within, or adjacent to tissue identified as having a predefined characteristic. Alternatively, in embodiments in which a medical system is used to perform step 416, step 416 may be performed in two steps, which may be performed simultaneously or separately. The first step includes applying a distally directed force to a first medical device of the medical system such that a distal end of the first medical device is inserted into the body passageway and into, within or adjacent to tissue identified as having a predefined characteristic, and the second step includes applying a distally directed force to a second medical device of the medical system such that a distal end of the second medical device is inserted into the lumen defined by the first medical device and into, within or adjacent to tissue identified as having a predefined characteristic.

[0095] The body passageway may include any suitable portion of the body, including an existing body passageway, a body lumen, and / or a body passageway created through tissue layers and / or fascia using a device described herein. Step 416 may be accomplished by scanning any suitable portion of the patient, and the selection of the suitable portion of the patient to scan may be based on various considerations, including the location of tissue having a predefined characteristic. Examples of portions of the patient that may be suitable for scanning include portions that include tissue having a predefined characteristic, portions that include a medical device, portions that include tissue having a predefined characteristic and a medical device, and any other portion of the patient that may be suitable for a particular embodiment. For example, the second portion of the patient may be the same or different from the first portion of the patient.

[0096] Step 418 may be accomplished by acquiring MR images from the MR scanner used in step 402 .

[0097] Step 420 may be accomplished by reviewing the MR images acquired in step 418 and verifying that the medical device is positioned in the desired location within the body passageway (e.g., at, within, or adjacent to tissue identified as having a predefined characteristic). This may be accomplished by visualizing one or more markers included on the medical device described herein or one or more image artifacts caused by the one or more markers. If the medical device is not positioned in the desired location, optional step 424 includes repeating steps 416, 418, and 420 to manipulate the position of the medical device (e.g., in real time, while scanning a portion of the patient that includes the tissue and / or medical device). Although steps 416, 418, and 420 have been shown as separate steps, these steps may optionally be completed simultaneously in real time (e.g., while scanning a portion of the patient that includes the tissue and / or medical device). Optional step 424 may be performed a suitable number of times to accurately position the medical device. Alternatively, in embodiments in which a medical system is utilized, step 420 may be performed by reviewing the MR images acquired in step 418 and confirming that the medical system (e.g., the first medical device and / or the second medical device) is positioned at a desired location within the body passageway (e.g., at, within, or adjacent to tissue identified as having predefined characteristics).

[0098] Step 422 may be accomplished by performing a treatment using a medical device. Any appropriate treatment may be performed and may be based on the tissue identified in step 408. Examples of treatments that may be suitable for performing include medical device-based treatments, biopsies, and any other treatments that may be suitable for a particular embodiment. Alternatively, in embodiments where a medical system is utilized, step 422 may be performed using the first medical device and / or the second medical device.

[0099] Each of steps 404, 406, 408, 410, 412, 414, 416, 418, 420, and / or 422 may be performed without the patient leaving the MR scanner in which the patient was placed at step 402. However, in alternative embodiments, the patient may be moved (e.g., out of the MR scanner in which the patient was placed at step 402, to another location) between one or more of the steps described herein, as desired.

[0100] Method 400 is believed to be advantageous at least because each step of method 400 is performed during a single (e.g., same day) patient visit using the same MR scanner, resulting in increased efficiency and reduced number of patient visits and procedures performed. This results in a set of procedures that allow a physician to visualize, diagnose, and treat a patient during a single patient visit. Although some steps are described as being completed while scanning a portion of a patient using an MR scanner and other steps are not described as being performed while scanning a portion of a patient using an MR scanner, any step described herein may be completed while scanning a portion of a patient using an MR scanner and / or an ultrasound device or without scanning a portion of a patient using an MR scanner. In embodiments in which ultrasound images are acquired, the acquired MR images may be electronically fused with real-time ultrasound images (e.g., transrectal ultrasound images of the prostate). Although some steps are described as being completed while scanning a portion of a patient using an MR scanner, the steps may be split into two separate steps such that a subsequent step of scanning a portion of a patient using an MR scanner may be accomplished. Additionally, any steps completed while scanning a portion of a patient using an MR scanner may include acquiring a single still image, which may be repeated any desired number of times to acquire multiple MR images that may be grouped as a cine to show motion, and / or any steps completed while scanning a portion of a patient using an MR scanner may include acquiring live images, such as being completed under live real-time MRI visualization.

[0101] FIG. 33 shows a schematic diagram of another exemplary method 500 of performing therapy under MRI.

[0102] A first step 502 includes positioning the patient in the MR scanner. Another step 504 includes scanning a first portion of the patient using the MR scanner. Another step 506 includes acquiring an MR image of the first portion of the patient. Another step 508 includes identifying tissue having predefined characteristics using the MR image. Another step 510 includes selecting a procedure to treat the tissue based on the predefined characteristics. Another step 512 includes selecting an MR sequence and / or parameters to use during the execution of the selected procedure. Another step 514 includes selecting a medical device to perform the execution of the medical procedure based on the selected MR sequence and / or parameters intended to be used during the execution of the selected procedure. While the patient is still positioned in the MR scanner used to scan a portion of the patient, another step 516 includes inserting the medical device into the body passage and up to the tissue while scanning a second portion of the patient including the medical device using the MR scanner. Another step 518 includes acquiring an MR image of the second portion of the patient including the medical device. Another step 520 includes verifying the position of the medical device in the body passage. Another step 522 includes inserting the biopsy device through the medical device to the tissue while scanning a third portion of the patient including the biopsy device using the MR scanner. Another step 524 includes acquiring an MR image of the third portion of the patient including the biopsy device. Another step 526 includes verifying the position of the biopsy device. Another step 528 includes taking a tissue sample from the tissue using the biopsy device while scanning a fourth portion of the patient including the biopsy device and the tissue using the MR scanner. Another step 530 includes acquiring an MR image of the fourth portion of the patient including the biopsy device. Another step 532 includes withdrawing the biopsy device and the tissue sample through the medical device. Another step 534 includes determining whether the tissue sample meets a predefined criterion. Another step 536 includes withdrawing the medical device.

[0103] Step 502 may be completed as described herein with respect to step 402. Step 504 may be completed as described herein with respect to step 404. Step 506 may be completed as described herein with respect to step 406. Step 508 may be completed as described herein with respect to step 408. Step 510 may be completed as described herein with respect to step 410. Step 512 may be completed as described herein with respect to step 412. Step 514 may be completed as described herein with respect to step 414. Step 516 may be completed as described herein with respect to step 416. Step 518 may be completed as described herein with respect to step 418. Step 520 may be completed as described herein with respect to step 420.

[0104] If the medical device is not located at the desired location, optional step 538 includes repeating steps 516, 518, and 520 to manipulate the position of the medical device (e.g., in real time, while scanning a portion of the patient that contains the tissue and / or medical device). Although steps 516, 518, and 520 have been shown as separate steps, these steps can optionally be completed simultaneously in real time (e.g., while scanning a portion of the patient that contains the tissue and / or medical device). Optional step 538 can be performed as many times as necessary to accurately position the medical device.

[0105] Step 522 may be accomplished by applying a distally directed force to the biopsy device such that the distal end of the biopsy device is inserted into and through a lumen defined by the medical device to tissue identified as having the predefined characteristic. Step 522 may be accomplished by scanning any suitable portion of the patient, and selection of the suitable portion of the patient to scan may be based on a variety of considerations including the location of tissue having the predefined characteristic. Examples of portions of the patient that may be suitable for scanning include portions that include tissue having the predefined characteristic, portions that include a biopsy device, portions that include tissue having the predefined characteristic and a biopsy device, and any other portions of the patient that may be suitable for a particular embodiment. For example, the third portion of the patient may be the same or different than the first portion of the patient and / or the second portion of the patient.

[0106] Steps 522, 524, 526, 528, 530, and / or 532 may be accomplished using any suitable biopsy device, such as an MRI compatible biopsy device, a device under the trade name MReye® offered by Cook Medical, an Echotip ProCore offered by Cook Medical, an Echotip Ultra offered by Cook Medical, and any other biopsy device deemed suitable for a particular embodiment. Alternatively, steps 522, 524, 526, 528, 530, and / or 532 may be completed using a biopsy device that is not MRI compatible. The one or more alternative steps may include inserting a biopsy device through the medical device to the tissue without scanning a portion of the patient that includes the biopsy device using a magnetic resonance scanner. An alternative to step 528 may include obtaining a tissue sample using a biopsy device without scanning a portion of the patient that includes the biopsy device and the tissue using a magnetic resonance scanner.

[0107] Step 524 may be performed by acquiring an MR image from the magnetic resonance scanner used in step 402 .

[0108] Step 526 may be accomplished by reviewing the MR images acquired in step 524 and verifying that the biopsy device is positioned in the desired location within the body passageway (e.g., at, within, or adjacent to tissue identified as having a predefined characteristic). This may be accomplished, for example, by including one or more markers described herein on a distal portion of the biopsy device. If the biopsy device is not positioned in the desired location, optional step 540 includes repeating steps 522, 524, and 526 to manipulate the position of the biopsy device (e.g., in real time, while scanning a portion of the patient that includes the tissue and / or medical device). Although steps 522, 524, and 526 have been shown as separate steps, these steps may optionally be completed simultaneously in real time (e.g., while scanning a portion of the patient that includes the tissue and / or medical device). Optional step 540 may be performed any suitable number of times to accurately position the biopsy device and may be utilized during performance of the procedure whenever the biopsy device, medical system, and / or device has been inserted, MR images have been acquired, and / or confirmation of placement of the medical system and / or device has been completed.

[0109] Step 528 may be performed using a biopsy device and conventional methods of obtaining samples using a biopsy device. Step 528 may be performed by scanning any suitable portion of the patient, and selection of the suitable portion of the patient to scan may be based on various considerations including the location of tissue having a predefined characteristic. Examples of portions of the patient that may be suitable for scanning include portions that include tissue having a predefined characteristic, portions that include a biopsy device, portions that include tissue having a predefined characteristic and a biopsy device, and any other portions of the patient that may be suitable for a particular embodiment. For example, the fourth portion of the patient may be the same as or different from the first portion of the patient, the second portion of the patient, and / or the third portion of the patient.

[0110] Steps 516, 522, and / or 528 may optionally be performed in combination with performing an ultrasound examination on the portion of the patient that includes the medical device and / or biopsy device. In embodiments where ultrasound images are acquired, the acquired MR images may be electronically fused with real-time ultrasound images (e.g., transrectal ultrasound images of the prostate).

[0111] Step 530 may be accomplished by acquiring MR images from the MR scanner used in step 402. An optional step includes verifying that a tissue sample has been taken. This optional step may be accomplished by reviewing the MR images acquired in step 530 and verifying that the biopsy device has taken a tissue sample (e.g., tissue identified as having a predefined characteristic). If the biopsy device has not taken a tissue sample, the optional step includes repeating steps 522, 524, 526, 528, 530, and / or this optional step.

[0112] Steps 506, 518, 524, and / or 530 may include acquiring a single still image, or steps 504, 516, 522, and / or 528 may be repeated any desired number of times such that steps 506, 518, 524, and / or 530 include acquiring multiple magnetic resonance images of a portion that may be grouped as a cine to show motion.

[0113] Step 532 may be accomplished by applying a proximal force to the biopsy device such that the biopsy device is withdrawn from the lumen defined by the medical device. In alternative embodiments, steps 522, 524, 526, 528, 530, and 532 may be omitted from method 500, and other methods described herein, and the medical device inserted in step 516 may be utilized to obtain a biopsy, and similar steps as described in connection with the biopsy device may be completed using the medical device.

[0114] Step 534 may be performed using any technique or method deemed suitable for determining whether or not tissue meets predefined criteria. For example, step 534 may utilize conventional techniques and methods for determining whether or not a tissue sample is malignant, such as frozen section and / or other cytological methods.

[0115] Each of steps 504, 506, 508, 510, 512, 514, 516, 518, 520, 522, 524, 526, 528, 530, 532, 534, and / or 536 may be performed without the patient leaving the magnetic resonance scanner in which the patient was placed at step 502. However, in alternative embodiments, the patient may be moved (e.g., to another location outside of the MR scanner in which the patient was placed at step 502) between one or more steps described herein, as desired.

[0116] Method 500 is believed to be advantageous at least because each step of method 500 is performed during a single (e.g., same day) patient visit using the same MR scanner, resulting in increased efficiency and reduced number of patient visits and procedures performed. This results in a set of procedures that allow a physician to visualize, diagnose, and treat a patient during a single patient visit. Although some steps are described as being completed while scanning a portion of a patient using an MR scanner and other steps are not described as being performed while scanning a portion of a patient using an MR scanner, any step described herein may be completed while scanning a portion of a patient using an MR scanner and / or an ultrasound device, or without scanning a portion of a patient using an MR scanner. In embodiments in which ultrasound images are acquired, the acquired MR images may be electronically fused with real-time ultrasound images (e.g., transrectal ultrasound images of the prostate). Although some steps are described as being completed while scanning a portion of a patient using a magnetic resonance scanner, the steps may be split into two separate steps such that a subsequent step of scanning a portion of a patient using an MR scanner may be accomplished. Additionally, any steps completed while scanning a portion of a patient using an MR scanner may include acquiring a single still image, which may be repeated any desired number of times to acquire multiple MR images that may be grouped as a cine to show motion, and / or any steps completed while scanning a portion of a patient using an MR scanner may include acquiring live images, such as being completed under live real-time MRI visualization.

[0117] FIG. 34 shows a schematic diagram of an exemplary method 600 for performing therapy under MRI.

[0118] A first step 602 includes placing a patient in an MR scanner. Another step 604 includes scanning a first portion of the patient using the MR scanner. Another step 606 includes acquiring an MR image of the first portion of the patient. Another step 608 includes identifying tissue having a predefined characteristic using the MR image. Another step 610 includes selecting a procedure to treat the tissue based on the predefined characteristic. Another step 612 includes selecting a medical device having a first pattern of markers to carry out the performance of the procedure. While the patient is still placed in the MR scanner used to scan the portion of the patient, another step 614 includes inserting the medical device having the first pattern of markers into a body passage and up to the tissue while scanning a second portion of the patient including the medical device using the MR scanner and the first pattern of image artifacts caused by the first pattern of markers using the MR scanner. Another step 616 includes acquiring an MR image of the second portion of the patient including the medical device and the first pattern of image artifacts caused by the first pattern of markers. Another step 618 includes identifying a first pattern of image artifacts in the MR images. Another step 620 includes changing the first set of MR image parameters and / or sequences to a second set of MR image parameters and / or sequences based on the identified first pattern of image artifacts. Another step 622 includes verifying the position of the medical device within the body passageway. Another step 624 includes delivering a treatment.

[0119] Step 602 may be completed as described herein in connection with step 402. Step 604 may be completed as described herein in connection with step 404. Step 606 may be completed as described herein in connection with step 406. Step 608 may be completed as described herein in connection with step 408. Step 610 may be completed as described herein in connection with step 410.

[0120] Step 612 may be accomplished using one or more of the medical devices described herein, one or more of the medical devices included in the medical device system described herein, and / or one or more of the medical devices included in the kit described herein. Each of the medical devices described herein comprises a pattern of markers. For example, FIG. 26 shows a first medical device 250 having a first pattern of markers 273 and a second medical device having a second pattern of markers 275. Each marker of the plurality of markers 270 included in the first pattern of markers 273 and the second pattern of markers 275 has a magnetic susceptibility that produces an image artifact 271, as shown in FIGS. 27 to 30. Alternatively, step 612 may include selecting a first medical device and a second medical device that together have a first pattern of markers.

[0121] Step 614 may be accomplished by applying a distally directed force to the medical device such that the distal end of the medical device is inserted into the body passageway and into, adjacent to, or tissue identified as having the predefined characteristic. Step 614 may be accomplished by scanning any suitable portion of the patient, and selection of the suitable portion of the patient to scan may be based on various considerations including the location of the tissue having the predefined characteristic. Examples of portions of the patient that may be suitable for scanning include portions including tissue having the predefined characteristic, portions including a medical device having a first pattern of markers that produce a first pattern of image artifacts, portions including tissue having the predefined characteristic and a medical device having a first pattern of markers that produce a first pattern of image artifacts, portions including a first medical device and a second medical device that together have a first pattern of markers that produce a first pattern of image artifacts, portions including tissue having the predefined characteristic and a first medical device and a second medical device that together have a first pattern of markers that produce a first pattern of image artifacts, and any other portions of the patient that may be suitable for a particular embodiment. For example, the second portion of the patient may be the same as or different from the first portion of the patient.

[0122] Step 616 may be accomplished by acquiring MR images from the MR scanner used in steps 602 and 616. Figures 29 and 30 show MR images showing exemplary medical devices 250, 251 disposed in porcine tissue. The first medical device 250 produces a first pattern of image artifacts 277 and the second medical device 251 produces a second pattern of image artifacts 279. The medical devices, or the combination of the first and second medical devices, may include any suitable pattern of markers to produce a pattern of image artifacts under MR imaging. For example, each medical device, or combination thereof, used to perform a treatment described herein may include a unique pattern of markers relative to the other medical devices used to perform the treatment.

[0123] Step 618 may be accomplished by reviewing the MR images acquired in step 616 and identifying a first pattern of image artifacts in the images. This may be accomplished using software (e.g., software having artifact recognition, localization, tracking, image processing, and / or machine learning) included in the MR scanner used in step 602 and / or visually by a clinician. For example, the MR scanner used in step 602 and the remaining steps included in method 600 may include a database that associates unique patterns of image artifacts with each medical device or combination of medical devices used to perform the treatment such that when a pattern of image artifacts is identified by the MR scanner during use, the MR scanner may identify and / or track the medical device or combination of medical devices, change a first set of MR image parameters and / or sequences to a second set of MR image parameters and / or sequences as described herein, and / or modify the images created by the MR scanner to create modified MR images. The database may include features of each pattern of image artifacts caused by a medical device or combination of medical devices, such as features such as size, shape, pattern, and / or intensity to identify a particular medical device. For example, each of the medical devices 50, 100, 130, 150, 170, 200, 240, 250, 251 has a pattern of markers that distinguish it from the other medical devices. As a result, each of the medical devices 50, 100, 130, 150, 170, 200, 240, 250, 251, or a combination of medical devices, produces a distinguishable image artifact (e.g., code) under MRI that can be identified using a database included in the MR scanner. Image processing software or machine learning can optionally be used to determine the status of these markers or image artifacts in near real-time, aiding in the estimation of device placement with automated sequence selection and enabling path planning to the target location to avoid critical or sensitive anatomical structures during treatment.

[0124] Step 620 may be performed using software included in the MR scanner used in step 602 and / or by the clinician. This step may be performed such that whenever an MR image is captured and / or an image artifact is detected, the MR image parameters and / or sequence are periodically modified or updated based on the image artifact caused by the marker or markers placed on the first medical device, the second medical device, and / or the combination of the first and second medical devices. The modified MR image may include an overlay graphic of the identified medical device (e.g., a portion of the medical device, the entire medical device), or combination of medical devices, with the first pattern of image artifacts, may include enhanced, attenuated, or omitted portions of the identified medical device (e.g., the distal end), combination of medical devices, image artifacts, or other objects in the image, and / or may include any other image manipulation deemed suitable for a particular embodiment.

[0125] Interventional MR procedures generally require frequent adjustments or changes to MR imaging sequence parameters throughout the various stages of a given procedure. For example, a vascular procedure may be optimally performed with one sequence type during device tracking (e.g., fast frame rate, low resolution, enhancement of specific tissue properties) and another sequence type once the interventional device has been inserted to the target site (e.g., higher resolution, emphasis on different tissue properties to detect lesions such as inflammation, ADC, etc.). Alternatively, one or more interventional devices may be employed across multiple MRI-based procedures, requiring specific imaging sequences for the particular device and procedure configuration. For example, an MRI-compatible needle may be used across multiple soft tissue biopsy procedures, each requiring different gross or fine tracking properties and emphasizing different anatomical structures or tissue types. Currently, many of these imaging protocols involve manual optimization by clinicians using MR scanners, which can lead to operator-to-operator variability and inefficiency.

[0126] Thus, method 600 provides a mechanism to at least increase the efficiency of delivering treatment. For example, software included in an MR scanner, such as that utilized to complete the methods described herein, may be utilized to provide automation of parameter adjustment throughout a procedure or across multiple procedures based on an identified pattern of image artifacts caused by a pattern of markers on a medical device, based on an identified pattern of image artifacts caused by a pattern of markers on a second medical device, and / or based on an identified pattern of image artifacts caused by a pattern of markers on a first medical device and a second medical device, as described herein. Thus, the presence of one or more image artifacts may be used to automate the selection of MRI sequence parameters.

[0127] Method 600 can be used to automatically change imaging parameters and / or sequences within a procedure or across multiple procedures using the same medical device or combination of medical devices. For example, changes in MRI sequence parameters (SE / GRE, TR, TE, flip angle, field of view, resolution, slice thickness, gradient fields) can be triggered by the identification of image artifacts by the MR scanner. These image artifact-driven triggers can be used to signal device tracking transitions to guide how the MR sequence is adapted to track devices or components among the magnetic fields of multiple devices and / or to adjust the MR sequence to highlight specific tissue characteristics during specific parts of the procedure.

[0128] For example, a series of consecutive MRI sequence parameters may be triggered sequentially based on the identified image artifacts. This process may then be used to automate the imaging protocol throughout the procedure. Alternatively, utilizing a first medical device and one or more second medical devices (e.g., various guiding catheters or balloon catheters) that are different from the first medical device but compatible with the first medical device, each with one or more patterns of markers, a particular imaging procedure involving the use of one or more second medical devices with the first medical device may be automated based on the identification of image artifacts caused by the combination of the first medical device with the one or more second medical devices. Using this detection of pairing, a set of pre-programmed MRI sequences may be automatically loaded and triggered by identifying the combined image artifacts. In other words, the combination of image artifacts caused by the combination of susceptibility markers on two or more medical devices serves as a unique pattern of image artifacts to identify a particular medical device pairing or device configuration that the MR scanner uses to automatically reconstruct parameters, sequences, procedures, or the next steps of the sequence or procedure.

[0129] Step 620 may be completed as described herein with respect to step 420. Step 622 may be completed as described herein with respect to step 422.

[0130] Each of steps 604, 606, 608, 610, 612, 614, 616, 618, 620, and / or 622 may be performed without the patient leaving the magnetic resonance scanner in which the patient was placed at step 602. However, in alternative embodiments, the patient may be moved (e.g., out of the MR scanner in which the patient was placed at step 602, to another location) between one or more of the steps described herein, as desired.

[0131] Method 600 is believed to be advantageous at least because each step of method 600 is performed during a single (e.g., same day) patient visit using the same MR scanner, resulting in increased efficiency and reduced number of patient visits and procedures performed. This results in a set of procedures that allow a physician to visualize, diagnose, and treat a patient during a single patient visit. Although some steps are described as being completed while scanning a portion of a patient using an MR scanner and other steps are not described as being performed while scanning a portion of a patient using an MR scanner, any step described herein may be completed while scanning a portion of a patient using an MR scanner, and / or an ultrasound device, or without scanning a portion of a patient using an MR scanner. In embodiments in which ultrasound images are acquired, the acquired MR images may be electronically fused with real-time ultrasound images (e.g., transrectal ultrasound images of the prostate). Although some steps are described as being completed while scanning a portion of a patient using a magnetic resonance scanner, the steps may be split into two separate steps such that a subsequent step of scanning a portion of a patient using an MR scanner may be accomplished. Additionally, any steps completed while scanning a portion of a patient using an MR scanner may include acquiring a single still image, which may be repeated any desired number of times to acquire multiple MR images that may be grouped as a cine to show motion, and / or any steps completed while scanning a portion of a patient using an MR scanner may include acquiring live images, such as being completed under live real-time MRI visualization.

[0132] Although several methods have been described herein, it will be appreciated that the methods may be non-invasive methods that do not require invasive intervention by a medical professional. For example, the methods may be performed in a body cavity or passageway, such as the ear canal or nasal cavity, to place a device therein. Similarly, the methods may be performed on a cadaver or artificial body part, for example for training purposes. Furthermore, those skilled in the art will recognize that the methods described herein may not be used on a human or animal body at all, but may be used to view other types of devices using MRI techniques, for example in an industrial setting.

[0133] Those skilled in the art will recognize that, in light of the overall teachings of the present disclosure, various modifications and alternatives to the described and illustrated examples can be developed, and that various elements and features of one example described and illustrated herein can be combined with various elements and features of another example without departing from the scope of the present invention. Therefore, the specific configuration of elements and steps disclosed herein has been selected by the inventors merely to describe and illustrate examples of the present invention, and is not intended to limit the scope of the present invention or its protection, which is given the full scope of the appended claims and any equivalents thereof.

Claims

1. a first medical device formed of a first material, the first material having a first magnetic susceptibility; a second medical device formed of a second material, the second material having a second magnetic susceptibility; and a marker disposed on the second medical device and formed of a third material, the third material having a third magnetic susceptibility different from the first magnetic susceptibility and the second magnetic susceptibility; and A medical system useful for performing treatment under magnetic resonance imaging, comprising:

2. The medical system of claim 1 , wherein the third magnetic susceptibility is greater than the first magnetic susceptibility and the second magnetic susceptibility.

3. The medical system of claim 1 , wherein the first material and the second material are the same.

4. The medical system of claim 3 , wherein the third material is an alloy containing less than 1% iron by weight.

5. The medical system of claim 1 , wherein the second medical device is operable coaxially with the first medical device.

6. The medical system of claim 1 , wherein the marker comprises a plurality of markers.

7. 7. The medical system of claim 6, wherein the plurality of markers includes a first subset of markers, a second subset of markers, and a third subset of markers, each marker in the first subset of markers formed from the third material, each marker in the second subset of markers formed from a fourth material, each marker in the third subset of markers formed from a fifth material, the fourth material having a fourth magnetic susceptibility different from the first magnetic susceptibility and the second magnetic susceptibility, and the fifth material having a fifth magnetic susceptibility different from the first magnetic susceptibility and the second magnetic susceptibility.

8. The medical system of claim 7 , wherein each of the first material and the second material is Inconel 625.

9. The medical system of claim 7 , wherein each marker in the first subset of markers is formed of nickel.

10. 8. The medical system of claim 7, wherein each marker in the second subset of markers is formed from a first alloy including less than 1% iron by weight.

11. 8. The medical system of claim 7, wherein each marker in the third subset of markers is formed from a second alloy including less than 1% iron by weight.

12. each of the first material and the second material is titanium; each marker in the first subset of markers is formed of stainless steel; each marker in the second subset of markers is formed from a first alloy including less than 1 weight percent iron; 8. The medical system of claim 7, wherein each marker in the third subset of markers is formed from a second alloy including less than 1% iron by weight.

13. each of the first material and the second material is titanium; each marker in the first subset of markers is formed of stainless steel; each marker in the second subset of markers is formed from a first cobalt chromium alloy; The medical system of claim 7 , wherein each marker in the third subset of markers is formed of a second cobalt chromium alloy different from the first cobalt chromium alloy.

14. an elongate member having a proximal end, a distal end, and a body formed of a first material having a first magnetic susceptibility; a plug disposed on the elongate member, the plug including a second material disposed within a third material, the second material having a second magnetic susceptibility, the third material having a third magnetic susceptibility, the second magnetic susceptibility being different from the first magnetic susceptibility and the third magnetic susceptibility; A medical device useful in performing treatment under magnetic resonance imaging, comprising:

15. The medical device of claim 14 , wherein the first material is different from the second material and the third material.

16. the second material comprises magnetically susceptible particles; The medical device of claim 14 , wherein the third material comprises an epoxy resin.

17. 17. The medical device of claim 16, wherein the magnetically susceptible particles comprise magnetically susceptible metal particles.

18. 20. The medical device of claim 17, wherein the magnetically susceptible metallic particles comprise a stainless steel alloy.

19. placing a patient in a magnetic resonance scanner; scanning a first portion of the patient using the magnetic resonance scanner; acquiring a magnetic resonance image of the first portion of the patient; identifying tissue having predefined characteristics using the magnetic resonance images; selecting a procedure for treating the tissue based on the predefined characteristics; selecting an MR sequence and / or parameters for performing the selected procedure; selecting a medical device to perform the selected procedure; While the patient is positioned within the magnetic resonance scanner used to scan the first portion of the patient, inserting the medical device into a body passageway and to the tissue while scanning a second portion of the patient containing the medical device using the magnetic resonance scanner; obtaining a magnetic resonance image of the second portion of the patient including the medical device; determining a position of the medical device within the body passageway; To provide treatment and A method for performing a treatment under magnetic resonance imaging, comprising:

20. The medical device comprises: an elongate member having a proximal end, a distal end, and a body formed of a first material having a first magnetic susceptibility; a plug disposed on the elongate member, the plug including a second material disposed within a third material, the second material having a second magnetic susceptibility, the third material having a third magnetic susceptibility, the second magnetic susceptibility being different from the first magnetic susceptibility and the third magnetic susceptibility; 20. The method of claim 19 comprising:

Images