Interventional MRI device with functional distal region configuration

Abstract

An interventional medical device, such as a catheter or guidewire, useful in a medical procedure guided under magnetic resonance imaging (MRI) includes an elongated member configured for insertion into a patient and having a flexible distal region. The flexible distal region has a preset curved shape in a relaxed state, but is elastically configurable to a second shape, different from the preset curved shape, by application of a force. The device includes at least first and second passive MRI markers located on the elongated member, each marker configured to produce a respective artifact under MRI. Various MRI marker location arrangements are described that facilitate identification or tracking of the location and / or configuration of the preset curved shape within the patient. Also described is an interventional system that includes at least first and second MRI markers, one of the markers being located on a first elongated member and the other of the markers being located on a second elongated member advanceable through the first elongated member. Related methods of manufacture and use are also described.

Description

[0001] Citation of relevant applications

[0002] This application claims the benefit of priority to U.S. Provisional Patent Application Serial No. 63 / 624,765, filed January 24, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure generally relates to the field of interventional medical procedures, and more specifically to elongated devices, such as guidewires or catheters, used in interventional medical procedures. Background Technology

[0004] Guidewires and catheters are commonly used in a variety of interventional medical procedures. Often, it is beneficial for guidewires or catheters to have a curved portion in the distal region, for example, to aid navigation during use or to minimize damage to patient tissues. In these or other procedures, it is sometimes desirable to have imageable markers to facilitate navigation and determine the location of the device.

[0005] Traditionally, interventional medical procedures have been primarily performed under X-ray guidance. Sometimes, radiopaque markers or marker lengths are included on the catheters and guidewires, which can be seen in the images during X-ray guidance. However, X-ray guidance exposes the patient to significant amounts of ionizing radiation.

[0006] Therefore, there is a need for improved and / or alternative medical devices and systems that allow for efficient visual observation or tracking during procedures guided by other imaging modalities, such as MRI. The aspects of this disclosure aim to address these needs. Summary of the Invention

[0007] In some aspects, this disclosure relates to an interventional medical device, such as a percutaneously insertable medical device, which is useful in procedures guided by magnetic resonance imaging (MRI). The medical device includes an elongated member configured for insertion into a patient and having a flexible distal region having a predetermined curved shape in a relaxed state, but which can be elastically shaped into a second shape, different from the predetermined curved shape, by applying force. A first passive MRI marker is disposed at a first location along the elongated member, the first passive MRI marker being configured to produce a first artifact under MRI. A second passive MRI marker is disposed at a second location distal to the first location along the flexible distal region, the second passive MRI marker being configured to produce a second artifact under MRI. The change in the relative position of the first passive MRI marker with respect to the second passive MRI marker as the flexible distal region moves from the second shape to the predetermined curved shape is visually detectable under MRI.

[0008] In other respects, this disclosure relates to an interventional medical device, such as a percutaneously insertable medical device, which is useful under magnetic resonance imaging (MRI). The device includes an elongated member configured for insertion into a patient and having a flexible distal region that has a predetermined curved shape in a relaxed state but can be elastically straightened into a straight state when force is applied. A first passive MRI marker is disposed at a first location along the elongated member. A second passive MRI marker is disposed at a second location along the elongated member, the second location being longitudinally spaced from the first location. The device is further characterized in that: (i) a first passive MRI marker is located proximal to a flexible distal region having a preset curved shape, and a second passive MRI marker is located on the flexible distal region having a preset curved shape, wherein the second passive MRI marker is closer to the first passive marker when the distal region is in the preset curved shape than when the distal region is in a straight state; or (ii) both the first and second passive MRI markers are on the flexible distal region having a shape memory of the preset curved shape and are longitudinally spaced apart from each other, and are configured to produce corresponding discrete visible artifacts under MRI at a main magnetic field strength of at least one of 0.55T, 1.5T, and 3T when the flexible distal region is in a straight state and the preset curved shape; or (iii) one of the first or second passive MRI markers is positioned on the distal region to mark the distal position of the preset curved shape.

[0009] In other respects, this disclosure relates to an interventional system, such as a percutaneously insertable interventional system, which is useful in medical procedures guided by magnetic resonance imaging (MRI) under a dominant magnetic field strength. The system includes a first elongated medical device, such as a catheter, for treating a target area of ​​a patient using a distal region of the first medical device. The first elongated medical device has a distal end and includes a first passive MRI marker. The system also includes a second elongated medical device, such as a guidewire, which is positioned through the lumen of the first elongated medical device to locate a distal region of the second elongated medical device distal to the distal end of the first elongated medical device. The distal region of the second elongated medical device includes the first passive MRI marker. The first passive MRI marker of the first elongated medical device is configured to produce a first medical device positioning artifact of maximum size under MRI. The first passive MRI marker of the second elongated medical device is configured to produce a second medical device positioning artifact of maximum size under MRI. The maximum size of the second medical device positioning artifact is greater than the maximum size of the first medical device positioning artifact.

[0010] Additional aspects of this disclosure relate to methods for manufacturing the interventional medical devices and systems described herein, and methods for using them. Further aspects of this disclosure, as well as the features and advantages of these aspects, will be apparent to those skilled in the art from the description herein. Attached Figure Description

[0011] In the accompanying drawings, the same reference numerals represent the same parts:

[0012] Figure 1 A longitudinal view of an exemplary conduit with a preset curved shape is depicted in this disclosure.

[0013] Figure 1A A longitudinal view of another exemplary catheter of this disclosure is depicted.

[0014] Figure 1B A longitudinal view of another exemplary catheter of this disclosure is depicted.

[0015] Figure 1C A longitudinal view of another exemplary catheter of this disclosure is depicted.

[0016] Figure 2 Depicting Figure 1 A magnified view of region M.

[0017] Figure 3 It depicts a state of being stretched out. Figure 1 A longitudinal view of the catheter.

[0018] Figure 4 Depicting in the direction Figure 1 After the preset curve shape shown is moved within a first range, Figure 3 A longitudinal view of the catheter.

[0019] Figure 5 Depicting in the direction Figure 1 After the preset curve shape shown is moved to the second range, Figure 4 A longitudinal view of the catheter.

[0020] Figure 6 Depicting the arrival at the third range of movement Figure 1 After setting the preset curve shape, Figure 5 A longitudinal view of the catheter.

[0021] Figure 7A The alternative catheters of this disclosure are described. Figure 1 A magnified view of region M.

[0022] Figure 7B Another alternative catheter described in this disclosure Figure 1 A magnified view of region M.

[0023] Figure 7C Another alternative catheter described in this disclosure Figure 1 A magnified view of region M.

[0024] Figure 7D Another alternative catheter described in this disclosure Figure 1 A magnified view of region M.

[0025] Figure 8 depicts a longitudinal view of an embodiment of the alternative catheter with a predetermined curved shape disclosed herein.

[0026] Figure 9A and Figure 9B Depicting along Figure 1 A cross-sectional view taken by line 1X-1X and the region within line 1X-1X. Figure 1 A longitudinal view of a segment of a catheter, illustrating an embodiment of a passive MRI marker.

[0027] Figure 10A and Figure 10B Depicting along Figure 1 A cross-sectional view taken by line 1X-1X and the region within line 1X-1X. Figure 1 A longitudinal view of a segment of the catheter, which illustrates another embodiment of a passive MRI marker.

[0028] Figure 11A and Figure 11B Depicting along Figure 1 A cross-sectional view taken by line 1X-1X and the region within line 1X-1X. Figure 1 A longitudinal view of a segment of the catheter, which illustrates another embodiment of a passive MRI marker.

[0029] Figure 12A and Figure 12B Depicting along Figure 1 A cross-sectional view taken by line 1X-1X and the region within line 1X-1X. Figure 1 A longitudinal view of a segment of the catheter, which illustrates another embodiment of a passive MRI marker.

[0030] Figure 13 A and Figure 13 B describes the lines along Figure 1 A cross-sectional view taken by line 1X-1X and the region within line 1X-1X. Figure 1 A longitudinal view of a segment of the catheter, which illustrates another embodiment of a passive MRI marker.

[0031] Figure 14A longitudinal view of an exemplary guidewire with a preset curved shape is depicted, wherein a portion of the guidewire sheath has been cut off to show the core component therein.

[0032] Figure 15 Depicting along Figure 14 A cross-sectional view taken from line 14X-14X.

[0033] Figure 16A Depicting along Figure 14 The cross-sectional view taken along line 14Y-14Y shows an embodiment of a passive MRI marker.

[0034] Figure 16B Depicting the area in the online 14Y-14Y region Figure 16A A longitudinal view of a section of the guidewire.

[0035] Figure 17A Depicting along Figure 14 The cross-sectional view taken along line 14Y-14Y shows another embodiment of a passive MRI marker.

[0036] Figure 17B Depicting the area in the online 14Y-14Y region Figure 17A A longitudinal view of a section of the guidewire.

[0037] Figure 18A Depicting along Figure 14 The cross-sectional view taken along line 14Y-14Y shows another embodiment of a passive MRI marker.

[0038] Figure 18B Depicting the area in the online 14Y-14Y region Figure 18A A longitudinal view of a section of the guidewire.

[0039] Figure 19A Depicting along Figure 14 The cross-sectional view taken along line 14Y-14Y shows another embodiment of a passive MRI marker.

[0040] Figure 19B Depicting the area in the online 14Y-14Y region Figure 19A A longitudinal view of a section of the guidewire.

[0041] Figure 20A Depicting along Figure 14 The cross-sectional view taken along line 14Y-14Y shows another embodiment of a passive MRI marker.

[0042] Figure 20B Depicting the area in the online 14Y-14Y region Figure 20AA longitudinal view of a section of the guidewire.

[0043] Figure 21 Local cross-sectional longitudinal views of interventional systems, including catheters and guidewires, are depicted, each with passive MRI markers.

[0044] Figure 22 Depicting Figure 21 The system was described graphically, and the visible artifacts produced by passive MRI markers were depicted. Detailed Implementation

[0045] Reference will now be made to embodiments, some of which are illustrated in the accompanying drawings, and these embodiments will be described using specific language. However, it will be understood that this is not intended to limit the scope of the disclosure. Those skilled in the art will generally appreciate any changes and further modifications to the described embodiments, as well as any other application of the principles described herein.

[0046] As disclosed above, aspects of this disclosure relate to interventional medical devices, such as catheters and / or guidewires, useful in MRI-guided procedures, and to interventional medical systems, and to methods for manufacturing and using them. In preferred forms, the interventional medical devices and systems are configured for percutaneous insertion into a patient and / or for performing endovascular procedures, such as endovascular procedures. For example, the catheter embodiments described herein may be configured for infusing a patient with a liquid therapeutic agent or diagnostic agent, and / or aspirating bodily fluids, such as blood, from a patient, and / or for measuring fluid pressures within a patient's blood vessels, such as blood pressure. In some embodiments, the catheters described herein may be, for example, an angiography catheter.

[0047] As used herein, the term "attachment" refers to one component being fixed to another such that the components do not become completely separated from each other during use in accordance with the intended purpose of the article, including components in their attached form.

[0048] As used herein, the term "plug" refers to a component having a size and construction suitable for placement within a hole, channel, groove, or cavity in another component. The term does not require any particular size or construction, and the size and construction of a particular plug will depend on the size and construction of the hole, channel, groove, or cavity in which the plug is intended to be placed.

[0049] As used herein, the term “perimeter” refers to the external or internal closed boundary of a body, element, or feature, without imposing any structural construction on the body, element, or feature.

[0050] As used herein, the term "passive MRI marker" refers to a quantity of first material positioned relative to a second material such that the first material produces discrete, visible artifacts on MRI that are distinguishable from the second material. In the embodiments described herein, the second material is typically represented by a material forming an elongated member such as a catheter shaft or guidewire, and has a lower magnetic susceptibility than the first material.

[0051] As used in this article, the term “passive” in relation to MRI markers means that the marker is not powered or is powered only by the electromagnetic field of the MR scanner.

[0052] As used herein, the “maximum size” of a visible artifact refers to the maximum edge-to-edge distance of the visible artifact on MRI. When referencing or requiring a numerical value for the maximum size of a visible artifact to determine the characteristics disclosed herein, it can be determined according to ASTM F2119-07 (2013) using a primary field strength of 0.55T and the following parameters:

[0053] Gradient echo sequence

[0054] Echo time (TE) [ms] 15

[0055] Repeat time (TR) [ms] 317

[0056] Flip angle [ 0 ]30

[0057] The matrix size is 256 x 256.

[0058] Layer thickness [mm] 10mm

[0059] Pixel bandwidth [Hz / px] 120

[0060] Field of view (FOV) [mm x mm] 400 x 400

[0061] As used herein, the term "magnetic susceptibility" refers to the inherent property of a material relating to the degree to which the material is magnetized in an applied magnetic field. When numerical values ​​of magnetic susceptibility are given herein, they refer to volume-based magnetic susceptibility expressed in the International System of Units (SI) at 25 °C. Some magnetic susceptibility values ​​are given herein in parts per million ("ppm"), and those skilled in the art will understand that reference to "ppm" is equivalent to reference to "x 10⁻¹⁰". -6 ".

[0062] Figure 1A longitudinal view of an exemplary flexible catheter 10 is depicted, including an elongated catheter shaft 12. The shaft 12 includes a flexible distal region 14 having a predetermined curved shape 16. The predetermined curved shape 16 may be a curved shape or include curved shapes that continuously bend about a point (an in-plane predetermined curved shape) or an axis (a predetermined curved shape extending out of the plane). As shown, the predetermined curved shape may be pigtail-shaped. In some forms, the predetermined curved shape 16 may facilitate non-invasive positioning of the catheter through and / or within anatomical structures, such as chambers of the heart (e.g., the left ventricle) or their associated valvular structures. While in the illustrated embodiment the predetermined curved shape 16 rotates approximately 360 degrees, it should be understood that in other forms the predetermined curved shape may rotate to smaller or larger degrees, such as at least 45 degrees, at least 90 degrees, at least 180 degrees, at least 270 degrees, or at least 360 degrees. In some typical forms, the predetermined curved shape 16 will rotate from approximately 270 degrees to approximately 540 degrees. The flexible distal region defines a distal end 18 of the catheter shaft 12. The catheter shaft 12 has a generally straight proximal shaft portion 20 attached to a curved distal portion 22 defining a predetermined curved shape 16. The length of the catheter shaft defining the curved distal portion is typically in the range of about 1 cm to about 20 cm, more typically about 5 cm to about 20 cm, or about 5 cm to about 15 cm. The catheter shaft 12 defines a longitudinal lumen 24 in fluid communication with a distal opening 26 at a distal end 18. The catheter 10 includes a first passive MRI marker 28, a second passive MRI marker 30, and a third passive MRI marker 32, which are longitudinally spaced from each other along the catheter shaft 12 (i.e., spaced along the longitudinal axis). The exemplary catheter 10 also includes a fourth passive MRI marker 33 positioned on the straight portion 20 at a relatively large longitudinal distance proximal to the next passive MRI marker appearing on the catheter 10 distal to the passive MRI marker 33 (providing a proximal reference marker). For example, this longitudinal distance is at least about two times, or at least about three times, the longitudinal distance between any two adjacent passive MRI markers among a plurality of passive MRI markers distal to the passive MRI marker 33 on the catheter 10. For example, such adjacent passive MRI markers may in some forms be passive markers 28 and 30 and passive markers 30 and 32, or may in some forms be passive MRI markers 28 and 32 (where passive MRI marker 30 is not included in the catheter), or may in some forms be passive MRI markers 28 and 30 (where passive marker 32 is not included in the catheter), or may in some forms be passive MRI markers 30 and 32 (where passive marker 28 is not included in the catheter).The length of catheter 10 between passive MRI marker 33 and the next passive MRI marker distal to passive MRI marker 33 may be free of any discrete MRI markers (i.e., free of any passive or active discrete MRI markers). In this way, under MRI, the relatively large interval between the corresponding visible artifacts produced by passive MRI marker 33 and the next discrete MRI marker distal to passive MRI marker 33 (e.g., passive MRI marker 28) can be observed or tracked, making marker 33 and its corresponding visible artifacts a useful positional reference for catheter 10 when used under MRI. Additionally or alternatively, the passive MRI marker 33 may be configured in some forms to produce visible artifacts under MRI that are different from (e.g., larger in size than (e.g., at least about 1.25 times) or alternatively smaller than) the visible artifacts produced by at least the next appearing discrete MRI marker (e.g., passive MRI marker 28) distal to the passive MRI marker 33, and in some forms by the corresponding visible artifacts produced by each of a plurality of passive MRI markers (e.g., passive MRI markers 28, 30, and 32) appearing distal to the passive MRI marker 33. This may also contribute to the function of the passive MRI marker 33 as a positional reference for the catheter 10 and its distal region 14.

[0063] Although four passive MRI markers are shown in the illustrated embodiment, any suitable number of passive MRI markers may be included on the catheter disclosed herein, including fewer or more than four. In the illustrated form, catheter 10 includes passive MRI markers 28 and 33 located on the straight portion 20 of catheter axis 12 near the distal region 14, and passive MRI markers 30 and 32 located on the distal region 14 of catheter axis 12. For other catheter embodiments or other medical device embodiments described herein, other arrangements are contemplated, including in some forms where at least one passive MRI marker is located on the straight portion 20 (e.g., at least marker 28 or at least marker 33) and at least one passive MRI marker (e.g., at least marker 30 or at least marker 32) or at least two passive MRI markers (e.g., both markers 30 and 32) are located on the distal region 14; or, where at least two passive MRI markers (e.g., both markers 28 and 33) are located on the straight portion 20 and at least one passive marker (e.g., at least marker 30 or at least marker 32) or at least two passive MRI markers (e.g., both markers 30 and 32) are located on the distal region 14.

[0064] Now combine Figure 2 refer to Figure 1 , Figure 2 It shows Figure 1A magnified view of region M. Passive MRI markers 28, 30, and 32 are configured to produce corresponding visible artifacts 28A, 30A, and 32A under MRI. In a particular configuration, passive MRI markers 28, 30, and 32 are configured to produce corresponding visible artifacts 28A, 30A, and 32A under MRI, with a maximum size approximately 1.5 to approximately 50 times, more preferably approximately 2 to approximately 20 times, the outer diameter of the longitudinal segment of the conduit axis 12 on which these visible artifacts appear. Under a given main magnetic field strength, the visible artifacts produced by the passive MRI markers under MRI may be the same as or different from each other. Furthermore, while the preferred maximum size is given above with reference to MRI at a main field strength of 0.55T, it should be understood that the device described herein will also produce visible artifacts and can be used for MRI at other main field strengths (e.g., 1.5T or 3T).

[0065] Now for reference Figures 3 to 6 The diagram illustrates several stages of the distal region 14 of the catheter's deployment from a generally straight configuration, wherein the distal region is maintained, for example, by extending a guidewire through the lumen 24, to be elastically moved to a predetermined curved state 16, for example, by withdrawing the guidewire proximally. Reference will be made below to the relative positions of the passive MRI markers 28, 30, and 32 and their corresponding artifacts 28A, 30A, and 32A, and as will be understood, their relative positions will be referenced within the overall shape of the catheter axis 12 (rather than their relative longitudinal positions along the catheter axis 12). Figure 3 The distal region 14, maintained in an upright position, is shown. As shown, passive MRI markers 28, 30, and 32 produce corresponding visible artifacts 28A, 30A, and 32A, which are discretely visible and spaced apart from each other. Marker 30 and its artifact 30A are located distal to marker 28 and its artifact 28A, respectively. Marker 32 and its artifact 32A are located distal to marker 30 and its artifact 30A, respectively. Marker 28 is located at a distance D1 from marker 32. In the first phase of deployment, as... Figure 4 As shown, marker 32 and its artifact 32A are positioned distal to marker 30 and its artifact 30A, while marker 30 and its artifact 30A are positioned distal to marker 28 and its artifact 28A, respectively. Figure 3 Compared to the case shown, marker 32 and its artifact 32A have been laterally moved relative to marker 28 and its artifact 28A, and also laterally moved relative to the axis of the generally straight portion 20 of the catheter shaft 12. Similarly, in this form and at this stage, marker 30 and its artifact 30A have been laterally moved relative to marker 28 and its artifact 28A, and also laterally moved relative to the axis of the straight portion 20.

[0066] Figure 5This illustrates the second phase of deployment following the first phase. (With) Figure 3 Compared to the illustrated configuration, marker 32 and its artifact 32A are now located proximal to marker 30 and its artifact 30A, respectively. Therefore, during deployment, marker 30 and its artifact 30A have moved from a position distal to marker 32 and its artifact 32A to a position proximal to marker 30 and its artifact 30A, respectively. During deployment of the preset curve shape 16, this relative movement between artifacts 32A and 30A can be visually observed by the user and / or tracked by the MRI system to provide deployment confirmation and estimate the position of the preset curve shape 16. While in the illustrated embodiment, marker 32 and its artifact 32A are held distal to marker 30 and its artifact 30A until a point where the axis 12 carrying marker 30 has been disengaged (e.g., via a guidewire), it should be understood that in other configurations, marker 32 and its artifact 32A may move from a distal position to a proximal position relative to marker 30 and its artifact 30A while the axis 12 carrying marker 30 remains constrained. The longitudinal spacing, preset curve shape, or other factors of markers 30 and 32 can be controlled to achieve these and other relative marker / artifact movements before and during deployment to the preset curve shape 16 in the distal region 14. Also in the illustrative form, the movement of artifact 32A from distal to proximal to artifact 30A is accompanied by orbital movement of artifact 32A around artifact 30A, which facilitates visual observation and / or MRI system tracking to determine the deployment and / or location of the distal region 14. Similarly, in Figure 3 , Figure 4 and Figure 5 In the stages shown, with them in Figure 1 Compared to the corresponding position in the roughly straight, undeployed state shown, artifact 32A has gradually moved closer to artifact 28A. Instead of or supplementing the relative movement between artifacts 32A and 30A discussed above, this relative movement between artifacts 28A and 32A can be observed by the user and / or tracked by the MRI system to provide deployment confirmation and estimate the position of the preset curve shape 16.

[0067] Figure 6 The distal region 14 of the catheter in the preset curved shape 16 is shown (also in... Figure 1(As shown in the diagram). It can be seen that marker 32 and its artifact 32A remain near marker 30 and its artifact 30A, and have moved even closer to them. Marker 32 and its artifact 32A have reached their positions closest to marker 28 and its artifact 28A, where passive marker 28 is located at a distance D2 from passive marker 32. These positions, and the associated movements of artifacts 28A, 30A, and 32A to these positions during the deployment of the distal region to the preset curved shape 16, can also be used to provide deployment confirmation and / or estimate the position of the preset curved shape 16.

[0068] Combination Figures 3 to 6 Advantageously, based on the above discussion, marker 28A is positioned near the proximal end of the distal region 14 formed by the curved distal portion 22. In the illustrative form, marker 28A is located on the generally straight portion 20 of the catheter axis 12, rather than on the distal region 14 formed by the curved distal portion 22. Marker 28 and its artifact 28A remain aligned with the axis of the generally straight portion 20 (this can, of course, be altered by contact with the patient's vessel wall). Thus, the position of artifact 28A can be used as a reference point for observing or tracking the movement of artifacts 30A and / or 32A. It is also preferable that the position of marker 28A on the catheter axis is within approximately 2 cm or approximately 1 cm of the proximal end of the distal region 14 (i.e., from the proximal origin of the curved distal portion 22). For these purposes, marker 28A may be positioned on the generally straight portion 20 proximal to the distal region 14, as shown; or in other forms, it may be positioned on the distal region 14, but preferably at a location where marker 28A is laterally offset from the axis of the straight portion 20 by no more than about 1 cm or no more than about 0.5 cm. Marker 28A thus distinguishes the transition between the straight portion 20 and the distal region 14. Similarly, on the distal region 14, relative to artifact 28, it is thus easier to observe or track the relative changes in spacing and movement between artifacts 30A and 32A.

[0069] In this respect, in some forms, the distal region 14 is in a predetermined curved shape 16 (see... Figure 6 In the case that the distance D2 between markers 28 and 32 does not exceed the straight construction in the distal region 14 (see...), Figure 3In some forms, the distance D1 between markers 28 and 32 is 90%, or no more than approximately 80%, 70%, 60%, or 50%, and in some forms, it is within the range of approximately 1% to approximately 90%, or approximately 1% to approximately 50%, of the distance D1. Additionally or alternatively, in some forms, considering the direction perpendicular to the axis of the straight proximal axial portion 20, the pre-defined curve shape 16 may have a maximum size 16D, which is in the range of approximately 0.5 cm to approximately 15 cm, typically approximately 1 cm to approximately 10 cm, and more typically approximately 1 cm to approximately 5 cm. It should be understood that the maximum size 16D will be selected based on the intended application and function of the catheter.

[0070] In some forms, marker 32 will be positioned near the distal end 18 of catheter 10, for example, within approximately 2 cm or approximately 1 cm of the distal end 18. Additionally or alternatively, in some forms, marker 30 will appear on catheter axis 12 at a location where the preset curve shape 16 has rotated between approximately 65 degrees and approximately 115 degrees, or between approximately 75 degrees and approximately 105 degrees; and / or marker 30 will appear on catheter axis 12 marking the distal position of the preset curve shape 16 and / or the laterally outermost position of the preset curve shape 16 relative to the axis of the straight portion 20. Where such distal and laterally outermost positions of the preset curve shape 16 differ, in some forms, the distal region 14 will have a passive MRI marker along its longitudinal direction marking the distal position of the preset curve shape 16, and another passive MRI marker along its longitudinal direction marking the laterally outermost position of the preset curve shape relative to the axis of the straight portion 20.

[0071] In some configurations, at least one of the markers 28, 30, and 32 is configured to produce a visible artifact of a size (e.g., maximum size) different from the size produced by at least one of the markers 28, 30, and 32. This difference can also aid in observing or tracing the shape of the distal region 14 of the catheter 10. For example, Figures 7A to 7D Various exemplary catheter embodiments are provided herein, wherein, unless otherwise stated, the corresponding catheters 7A to 7D shown may be identical to catheters 10 or 10' herein. Figure 7A In catheter 7A, passive MRI marker 28 is configured to produce a visible artifact 28A, passive MRI marker 30 is configured to produce a visible artifact 30A, and passive MRI marker 32 is configured to produce an artifact 32A, wherein artifact 28A is larger than artifact 30A (e.g., has a larger maximum size), and artifact 30A is larger than artifact 32A (e.g., has a larger maximum size). Figure 7B In catheter 7B, passive MRI marker 28 is configured to produce a visible artifact 28A, passive MRI marker 30 is configured to produce a visible artifact 30A, and passive MRI marker 32 is configured to produce an artifact 32A, wherein artifact 32A is larger than artifact 30A and artifact 28A (e.g., having a larger maximum size), and artifacts 30A and 28A may have the same size as each other (e.g., maximum size). Figure 7C In catheter 7C, passive MRI marker 28 is configured to produce a visible artifact 28A, passive MRI marker 30 is configured to produce a visible artifact 30A, and passive MRI marker 32 is configured to produce an artifact 32A, wherein artifact 30A is larger than artifacts 28A and 32A (e.g., having a larger maximum size), and artifacts 28A and 32A may have the same size as each other (e.g., maximum size). Figure 7D In the catheter 7D, passive MRI marker 28 is configured to produce a visible artifact 28A, passive MRI marker 30 is configured to produce a visible artifact 30A, and passive MRI marker 32 is configured to produce an artifact 32A, wherein artifact 28A is larger than artifacts 30A and 32A (e.g., having a larger maximum size), and artifacts 30A and 32A may have the same size as each other (e.g., maximum size).

[0072] The size of visible artifacts produced by passive MRI markers, such as the maximum size, can be controlled in any suitable manner. Varying the volume and / or composition of the passive MRI marker-forming material of the corresponding passive MRI marker can be used for these purposes. For example, in some forms, a passive MRI marker that produces an artifact larger in size (e.g., a larger maximum size) than another artifact may comprise a larger volume of the same MRI marker-forming material. In other forms, a passive MRI marker that produces an artifact larger in size than another artifact may comprise a passive MRI marker-forming material different from another passive MRI marker-forming material. In this form, a passive MRI marker that produces a larger artifact may have a passive MRI marker-forming material of the same or smaller volume with a higher magnetic susceptibility than another passive MRI marker; or, it may have a passive MRI marker-forming material of a larger volume with a lower magnetic susceptibility than another passive MRI marker. It should be understood that these passive MRI marker configurations are applicable to markers 28, 30, 32 and 33 of catheter 10 and other catheters herein, as well as passive MRI markers of different sizes on other devices disclosed herein, including guidewires.

[0073] Advantageous embodiments are provided in which, when the distal region 14 is in a predetermined curved shape 16, markers 28, 30, and 32 provide a pattern specific to the predetermined curved shape 16, which can be visually observed by a user and / or detected by an MRI system to confirm that the distal region 14 is deployed into the predetermined curved shape 16. For example, in some embodiments, markers 28, 30, and 32 may be positioned as linear patterns extending in a direction offset from the axis of the proximal axial portion 20 of the catheter 10, for example, wherein markers 28, 30, and 32 and their corresponding artifacts 28A, 30A, and 32 are linearly positioned, but are spaced closer together than when the distal region 14 is in a straight position. Other positional patterns may include, for example, polygonal patterns. These or other positional patterns may also benefit from the different sizes between the artifacts 28A, 30A, and 32A generated by the passive MRI markers 28, 30, and 32, for example as described above. The MRI system can be configured to use a computer processor to detect such positional and / or artifact-sized patterns, for example, by using artificial intelligence (AI) to train the computer processor to recognize such patterns, and to perform functions controlled by the computer processor based on this detection. For example, the MRI system can provide signals, such as auditory signals through a speaker or visual graphics on an electronic display (such as a display showing MRI images), where the graphics are potentially provided as an overlay of the MRI images. This graphic overlay can, for example, estimate the shape and / or size of the distal region 14, and / or provide indications of the distal and / or laterally outermost positions of a preset curved shape 16. User input devices, such as the system's keyboard, can be used as controllers to display or not display the graphics as needed.

[0074] The above discussion includes the deployment of the distal region 14 from a straight state to the predetermined curved shape 16, and the relative movement of markers 28, 30, and 32 and their corresponding artifacts 28A, 30A, and 32A during such deployment. It should be understood, of course, that in actual use of the catheter 10, when deployment begins, the distal region 14 may not be in a straight state, but rather in a curved state, not the predetermined curved shape 16, due to conditions at the treatment site and / or constraints of the guidewire or other associated interventional devices. Nevertheless, the relative movement of the artifacts 28A, 30A, and 32A can be effectively observed or tracked to determine the deployment and / or estimate the location of the predetermined curved shape 16.

[0075] Turning now to some more specific features of an illustrative embodiment of catheter 10, in a preferred form, the elongated catheter shaft 12 has a generally circular outer profile in cross-section. Catheter shaft 12 may include a proximal shaft portion 34 and a distal shaft portion 36, the distal shaft portion being securely attached to the proximal shaft portion at a junction 38, which may be, for example, a thermally bonded junction. The distal shaft portion 36 may be a radiopaque and / or MRI-visible tubular component portion, or in some forms, not a radiopaque and / or MRI-visible tubular component portion. The distal shaft portion 36 may be formed of a flexible polymer material, such as a thermoplastic elastomer. In some forms, shaft portion 36 may comprise a uniformly dispersed composition of a thermoplastic elastomer material and a radiopaque and / or passive MRI artifact-generating material. In other forms, shaft portion 36 may contain no radiopaque material and no passive MRI artifact-generating material.

[0076] The catheter 10 also includes a proximal end 40 having a connector cap 42 and a female Luer lock connector 44 positioned around the connector cap for a physician or other user to grasp and manipulate the catheter 10. The catheter 10 also includes a lumen 24 extending longitudinally therein between a proximal opening 46 and a distal opening 26. Figure 1 The catheter 10 shown also includes a side port 48 communicating with the lumen 24, as shown. The side port is formed in the proximal axial portion 20 of the catheter 10, but in other forms, the side port may or alternatively appear only in the distal region 14 of the catheter 10. Similarly, in some forms, the catheter 10 may have a closed distal end 18 (instead of having an opening 26) and one or more side ports in the proximal portion and / or distal region 14.

[0077] The proximal axial portion 34 of the catheter 10 may have a length of, for example, about 50 to about 150 cm. The flexible polymeric material forming the proximal axial portion 34 may include a thermoplastic elastomer material. Thermoplastic elastomer materials may include polyamide elastomers, such as commercially available elastic nylon-12. Alternative thermoplastic elastomer materials that may be used include polyester elastomers, polyurethanes, and polyether block amides. In some forms, the proximal axial portion 34 may include a radiopaque material and / or MRI artifact-generating material dispersed in the thermoplastic elastomer or other polymeric material forming the portion 34. Potential radiopaque materials include, for example, particulate materials such as bismuth oxychloride, basic bismuth carbonate, bismuth trioxide, and barium sulfate. If present, the radiopaque agent preferably has a magnetic susceptibility of less than about 500 ppm. Potential MRI artifact-generating materials include, for example, material particles with a magnetic susceptibility greater than about 500 ppm, preferably greater than about 2000 ppm. Examples of MRI artifact-generating particles include particles of nickel, nickel alloys, iron, iron alloys, or titanium. The combination of radiopaque material and discrete passive MRI markers (e.g., markers 28, 30, 32) can provide catheters that can be advantageously used for X-ray-guided and MRI-guided interventional procedures. The combination of MRI artifact-generating material dispersed in the polymer material of the catheter axis 12 and discrete passive MRI markers (e.g., markers 28, 30, 32) can provide catheters that produce both elongated, continuous visible artifacts longitudinally along axis 12 and discrete artifacts (e.g., artifacts 28A, 30A, 32A). Preferably, the discrete artifacts have a larger maximum size in a direction perpendicular to the longitudinal axis of axis 12 than the continuous artifacts, which further aids in tracking and / or identifying the location of the catheter.

[0078] The distal axial portion 36 of the catheter 10 may be, for example, a flexible polymer material ranging from 5 cm to 20 cm in length, which may be softer and more flexible, and / or less rigid than the proximal axial portion 34. The flexible polymer material of the distal axial portion 34 may include a thermoplastic elastomer material. The thermoplastic elastomer material may include polyether block amide. Alternative thermoplastic elastomer materials that may be used include polyester elastomers, polyurethanes, and polyamide elastomers, such as elastic nylon-12. Similar to the proximal axial portion 34, in some forms, the distal axial portion 36 may include a radiopaque material and / or MRI artifact-generating material dispersed in the thermoplastic elastomer or other polymer material forming the portion 36. Potential radiopaque materials and potential MRI artifact-generating materials include those discussed above for the proximal axial portion 34 as examples. In some forms, the polymer material forming both the proximal axial portion 34 and the distal axial portion 36 may include radiopaque materials and / or MRI artifact-generating materials dispersed therein. In other forms, the polymeric material forming one or the other of portions 34 and 36 will include radiopaque material and / or MRI artifact-generating material dispersed therein. In other forms, the polymeric material forming portion 36 will include radiopaque material and / or MRI artifact-generating material dispersed therein, and the polymeric material forming portion 34 will include radiopaque material dispersed therein, but for example, due to the different concentrations and / or different radiopaque materials within portions 34 and 36, the radiopaque linearity of portion 34 will be lower than that of portion 36.

[0079] Furthermore, although the shaft 12 having the attached portions 34 and 36 has been discussed in conjunction with the above embodiments, it should be understood that in other embodiments, the shaft 12 may also be formed of a single continuous polymer material, such as any thermoplastic elastomer discussed herein. Similarly, as described above, the inclusion of radiopaque materials and / or MRI artifact-generating materials dispersed in the polymer material may be incorporated into such other embodiments.

[0080] In some forms, the distal region 14 of the catheter shaft 12, or the distal portion 36 of the catheter shaft when including the proximal shaft portion 34 and the distal shaft portion 36, or the catheter shaft 12 as a whole, does not contain any metal reinforcement members, such as wire coils or wire braids. Thus, in some embodiments, the proximal portion 34 of the catheter shaft 12 includes metal reinforcement members, such as wire coils or wire braids, while the distal portion 36 of the catheter shaft 12 does not. In other forms, the catheter shaft 12, or, when attached shaft portions 34 and 36 are present, at least the distal portion 36, does not contain any metal other than the metal contained in passive MRI markers (such as markers 28, 30, 32, and / or 33) within the catheter 10.

[0081] In some embodiments, when passive MRI markers 28 and 30 are present, the catheter shaft 12 may contain no discrete MRI markers between them; or when passive MRI markers 30 and 32 are present, no discrete MRI markers between them; or when passive MRI markers 28 and 32 are present, no discrete MRI markers between them. In some forms, when passive MRI markers 28, 30, and 32 are present, the length of the catheter shaft including markers 28, 30, and 32 may contain no other discrete MRI markers. Furthermore, in embodiments where passive MRI marker 33 is present, when passive MRI marker 33 and passive MRI marker 28 are present, the catheter shaft 12 may contain no discrete MRI markers between them; or when passive MRI marker 28 is absent, no discrete MRI markers between passive MRI marker 33 and passive MRI marker 30 are present.

[0082] Now refer to Figures 8A to 12B Various advantageous embodiments of passive MRI markers are described herein. While the discussion specifically relates to passive marker 28, it should be understood that passive markers 30 and 32 and / or other passive MRI markers discussed herein may have the features discussed.

[0083] Figure 8A and Figure 8B The view shown depicts an illustrative structure of a passive MRI marker 28. In this form, the marker 28 is a plug 50 embedded within a polymeric material of the wall of the catheter shaft 12. The plug 50 comprises a material having a magnetic susceptibility suitable for producing visible artifacts under MRI, as described herein (here, sometimes referred to as "passive MRI marker forming material"). Suitable materials have been found to be used in relatively small amounts for these markers. Preferred materials for these purposes will have a magnetic susceptibility of at least about 500 ppm or at least about 2000 ppm, and typically in the range of about 500 ppm to about 1,000,000, and more preferably in the range of about 7000 ppm to about 100,000. In some forms, the volume of the marker forming material will not exceed 5 mm. 3 or no more than 3 mm 3 or not more than 1 mm 3 or not exceeding 0.1 mm 3 In each of these aspects, the volume can be at least 0.00005 mm. 3 or at least about 0.0001 mm 3 In a more preferred form, where a material with relatively high magnetic susceptibility is used, for example, a magnetic susceptibility of at least about 1 (e.g., nickel, with a magnetic susceptibility of about 1.1), the volume does not exceed 0.1 mm. 3For example, in 0.00001 mm 3 Up to 0.1 mm 3 Within the range, or 0.00005 mm 3 Up to 0.02 mm 3 A range of passive MRI marker-forming materials can be used to form passive MRI markers. Specific materials that can be used are discussed below. It should be understood that, generally, the higher the magnetic susceptibility exhibited by the MRI marker-forming material, the smaller the volume of this material required to form a visible artifact of a given size. Those skilled in the art can select and control these aspects to provide passive MRI markers configured to produce visible artifacts of a given or relative size, as described herein.

[0084] The ability to form materials using relatively small volumes of passive MRI markers while still producing visible artifacts of a beneficial size is advantageous because it allows for the incorporation of markers while minimizing interference with the physical properties of the catheter shaft, which are typically carefully designed using relatively soft and flexible polymeric materials. In the illustrated embodiment, the plug 50 is entirely located within the tubular wall of the catheter shaft 12, the tubular wall having a first volume 52 of polymeric material (from which the catheter shaft is formed) appearing radially outward of the plug 50 and extending to the outer surface of the shaft 12, and a second volume 54 of such polymeric material appearing radially inward of the plug 50 and extending to the surface of the catheter lumen 24. This arrangement can be achieved, for example, by the fabrication method embodiments described herein, which involve inserting the plug 50 into an opening in the wall of the shaft 12, the opening extending from the outer surface of the wall and only partially through the thickness of the wall, and filling the opening with a molten volume of polymeric material (from which the shaft 12 is formed) and forming a new outer surface portion of the shaft 12 above the plug 50. For these purposes, the polymer material can be heated before, during, and / or after the insertion of the plug 50, for example by ultrasonic or other means, to melt, flow, and fill the opening and surround the plug 50, and then cooled (e.g., passively or actively) to solidify. The plug 50 can be mounted to a heated end of a probe, such as an end heated by ultrasonic waves, for insertion into the wall of the shaft 12. The probe can heat the plug 50 and the polymer material during insertion, and also after the plug 50 has deposited in the wall of the shaft and during its withdrawal from the polymer material. This can help allow the polymer material to flow and surround the plug, and fill the plug with a first volume 52 of polymer material. This technique can help enable the self-healing of the polymer material as a new outer surface of the shaft 12 is formed above the plug 50.

[0085] Figure 9A and Figure 9BThe view shown depicts another illustrative structure of a passive MRI marker 28. In this form, marker 28 is a plug 60 embedded within the wall of the catheter shaft 12. Unlike the polymeric material from which the wall of the shaft 12 is formed, a solid filler material 62 appears radially outside the plug 60 and provides a covering surface 64 of the filler material, which in some forms may be substantially flush with the adjacent surface of the catheter shaft 12. The filler material 62 may be, for example, an adhesive, such as a polymeric adhesive. Similar to the plug 50 described above, plug 60 comprises a material having a magnetic susceptibility suitable for producing visible artifacts under MRI, as described herein.

[0086] Figure 10A and Figure 10B A view depicting another illustrative structure of a passive MRI marker 28 is provided. In this form, marker 28 is a plug 70 within the wall of the catheter shaft 12. Plug 70 is formed of particulate material 72 having a magnetic susceptibility suitable for producing visible artifacts under MRI, as described herein, dispersed within a matrix material 74, such as a polymer matrix material (which may be the same as or different from the polymer material forming the shaft 12) and / or an adhesive matrix material. Plug 70 provides a surface 76 that is flush with the adjacent surface of the shaft 12. This arrangement in the form of marker 28 can be produced by filling an opening created in the wall of the catheter shaft 12 with a flowable material comprising a precursor (e.g., an adhesive) of particulate material 72 and matrix material 74, and curing the precursor material to form matrix material 74.

[0087] As described herein, the flexible distal region 14 of catheter 10 has a predetermined curved shape 16. The catheter shaft portion 22, situated within the predetermined curved shape 16, may have an innermost portion 16' or "inner ridge" extending along a line extending along a first curve, and an outermost portion 16" or "outer ridge" extending along a line extending along a second curve opposite to the first curve on the shaft portion 22. Similarly, as described herein, in some forms, the MRI marker may be a plug of MRI marker-forming material embedded in the wall of the catheter. In some preferred forms, when present in the flexible distal region 14 of the catheter having the predetermined curved shape 16, such a plug-type marker will be positioned on the periphery of the catheter shaft 12 so as not to overlap with the innermost portion 16' and / or the outermost portion 16" , for example, in some forms, so as to surround the outer periphery of the catheter shaft 12 at at least approximately 15 degrees, or around... The outer periphery of the catheter axis 12 is circumferentially spaced from the innermost portion 16' and / or the outermost portion 16” at at least approximately 30 degrees. This position of the plug-type passive MRI marker may be selected to provide embodiments that apply relatively low stress to the marker during movement of the distal region 14 between the preset curved shape 16 and a straightened state, for example, where the marker neither overlaps with the inner ridge nor its outer ridge of the preset curved shape 16. Similarly, in some catheter configurations, this position of the plug-type MRI marker may help maintain the flexibility of the preset curved shape 16 provided by the polymer material forming it, for example, when the outermost portion 16” of the preset curved shape 16 is pressed against the patient's anatomical surface while the flexible distal region 14 is in the preset curved shape 16.

[0088] Figure 11A and Figure 11B A view depicting another illustrative structure of a passive MRI marker 28 is provided. In this form, marker 28 is a strip 80 of MRI marker-forming material extending around the outer periphery of axis 12 and providing an outer strip surface 82 on axis 12. Strip 80 may include a matrix material 84 in which particles 86 of the MRI marker-forming material are dispersed. In some aspects, strip 80 may be formed by curing a flowable material applied to the axis, the flowable material comprising precursors of matrix material 84 and particles 86, for example, wherein the flowable material has the properties of MRI marker-forming ink, the MRI marker-forming ink may further include a colorant selected to provide contrast between adjacent surfaces of strip 80 and axis 12.

[0089] Figure 11A and Figure 11BA view depicting another illustrative structure of a passive MRI marker 28 is provided. In this form, marker 28 is a strip 80 of MRI marker-forming material extending around the perimeter of axis 12 and providing an outer strip surface 82 on axis 12. Strip 80 may include a matrix material 84 in which particles 86 of the MRI marker-forming material are dispersed. In some aspects, strip 80 may be formed by curing a flowable material applied to the axis, the flowable material comprising precursors of matrix material 84 and particles 86, for example, wherein the flowable material has the properties of MRI marker-forming ink, the MRI marker-forming ink may further include a colorant selected to provide contrast between adjacent surfaces of strip 80 and axis 12.

[0090] Figure 12A and Figure 12B A view depicting another illustrative structure of a passive MRI marker 28 is provided. In this form, marker 28 is a band 90 of MRI marker-forming material trapped between an inner tubular axial layer 12A and an outer tubular axial layer 12B, the inner and outer tubular axial layers being attached (e.g., bonded) to form a duct axial 12. The respective polymeric materials of the forming layers 12A and 12B may be the same or different from each other, and in some respects, may be selected from any polymeric material disclosed herein. In fabricating this illustrated arrangement of marker 28, in some forms, the band 90 may be provided by applying a flowable material (such as the flowable material discussed above for band 80) to the outer surface of the tubular axial layer 12A, and then attaching the axial layers 12A and 12B to each other to form the axial 12. In other forms, the band 90 may be a solid membrane or ring located on the outer surface of the tubular axial layer 12A, and then attaching the axial layers 12A and 12B to each other to form the axial 12.

[0091] The advantage is that the above combination Figures 8A to 12BThe markers discussed herein, or other markers herein, may appear in a relatively small area of ​​shaft 12. For example, such markers may appear in a longitudinal length not exceeding 10 mm or 5 mm, and typically in the range of 0.2 to 5 mm; and / or, in the case of plug-type markers or some non-perimeter layer markers, may have a width perpendicular to the axis of shaft 12, which does not exceed approximately 90%, or approximately 80%, or approximately 70%, of the corresponding width of shaft 12, or in the range of approximately 10% to approximately 100%, or approximately 10% to approximately 70% of the corresponding width of shaft 12. Markers including plugs as described above are particularly advantageous for application within such widths and such longitudinal lengths. Passive MRI markers positioned in such limited areas can help avoid or minimize any impact of the markers on the physical properties of shaft 12, such as bending or elastic properties, caused by any damage to the passive MRI marker forming material, any other material associated therewith (e.g., adhesives), or the polymeric material forming the shaft during the bonding of the passive MRI marker forming material.

[0092] Specific passive MRI marker forming materials that may be used herein include, for example, nickel, nickel alloys, iron, iron alloys, cobalt, cobalt alloys, or other suitable metals. These materials may be selected to have magnetic susceptibility values ​​as discussed herein, and / or in some forms, these materials may be paramagnetic or ferromagnetic. In some advantageous forms, the passive MRI marker forming material will be incorporated, as a continuous volume of passive MRI marker forming material, for example, as a plug or layer (e.g., a plating), within a certain length of the catheter shaft 12 or another elongated member of the medical device of this invention. For example, this continuous volume form of the passive MRI marker of this invention can help minimize the material volume that needs to be added to and / or replaced in forming the catheter shaft 12 or other elongated members of the medical device of this invention, compared to passive MRI marker forms comprising particles of passive MRI marker forming material dispersed in a volume of another material providing a solid matrix.

[0093] Figure 13A longitudinal view of another illustrative flexible catheter 10' is depicted. Catheter 10' may have the same features as catheter 10 described above, unless otherwise stated herein. Catheter 10' has lateral port features different from those of catheter 10. In particular, catheter 10' does not contain any lateral ports appearing proximal to marker 28 and includes one or more lateral ports 48A located distal to marker 28. In this way, marker 28 provides an indication to a physician or other user of catheter 10' that all lateral ports 48A of catheter 10' are located distal to the artifact 28A produced by marker 28. This can be useful, for example, when delivering flowable diagnostic or therapeutic material through lumen 24 to a selected target area where lateral ports 48A are located, and / or when positioning lateral ports 48A within a given area of ​​a patient's blood vessels (such as within the heart) to measure pressure within the area. These and other variations in the structure of catheters 10 and 10' that benefit from the presence and function of passive MRI markers will be apparent to those skilled in the art from the description herein.

[0094] in this regard, Figure 1A , Figure 1B and Figure 1C Additional embodiments of catheters 10A, 10B, and 10C are depicted, each having a distal region with a predetermined curved shape. Catheters 10A, 10B, and 10C may have the same features as catheters 10 or 10', unless otherwise stated herein. Figure 1A The catheter 10A has a preset curved shape 16A that rotates continuously by approximately 180 degrees. Markers 28, 30, 32 and 33 are functionally corresponding to the marks on catheters 10 and 10' discussed above. Figure 10BThe catheter 10B has a pre-defined curve shape 16B with multiple curves, and in particular, a reverse curve shape. The pre-defined curve shape 16B includes a proximal curve portion 22A and a distal curve portion 22B of the distal region 14. The proximal curve portion curves in a first direction laterally to the longitudinal axis of the straight portion 20 of the catheter axis 12, and the distal curve portion extends adjacent to the proximal curve portion in a second direction laterally to the longitudinal axis of the straight portion 20, and the second direction is opposite to the first direction of the proximal curve portion 22A. As is known in the art, the pre-defined curve shape 16B is a "shepherd's hook" pre-defined curve shape. The catheter 16B also includes another passive MRI marker 28'. The catheter 16B exemplifies the embodiments described herein, having a passive MRI marker 30 positioned on a predetermined curved shape 16B to provide visual artifacts marking the most distal location of the predetermined curved shape 16B, and another passive MRI marker 28' positioned on the predetermined curved shape 16B to provide visual artifacts marking the laterally outermost location of the predetermined curved shape 16B. Similarly, for observing or tracking the deployment of the predetermined curved shape 16B, particularly its distal curved portion 22B, the passive MRI marker 28' can function similarly to the passive MRI marker 28 in terms of movement and relative position with respect to the passive MRI markers 30 and 32. Figure 1C The catheter 10C illustrates a catheter with another preset curve shape 16C. The preset curve shape 16C is rotated less than 180 degrees, particularly approximately 85 degrees in the illustrated form, having a smaller radius bend near the proximal end of the distal region 14, extending distally to a larger radius bend and / or straight portion of the preset curve shape 16C. As will be understood, in the case of the preset curve shape 16C, during and within the deployed preset curve shape 16C, the passive MRI marker 32 will remain distal to the passive MRI marker 30, rather than moving proximal to the passive MRI marker 30 as in the other catheters described above (e.g., catheters 10, 10', 10A, and 10B). However, the relative position and movement of the markers 28, 30, and 32 of the catheter 10C, and their corresponding visible artifacts, can be observed or tracked to determine the deployment of the preset curve shape 16C. Catheters 10A, 10B, and 10C may have one or more side ports at locations disclosed for catheter 10 or catheter 10', or in other forms may be without any side ports along axis 12, having only end openings 26 positioned for fluid communication of lumen 24 within a patient, for example for receiving patient fluids such as blood and / or infusing liquid preparations into a patient.

[0095] In some preferred manufacturing methods, passive MRI markers on the flexible distal region 14 of the catheter 10 may be incorporated before the distal region 14 is set to a predetermined curve shape 16. Setting the distal region 14 to the predetermined curve shape 16 may include forcing and holding the polymer material of the catheter shaft 12 into a desired shape corresponding to the predetermined curve shape, heating the polymer material of the catheter shaft 12 while it is in this desired shape, and then cooling the polymer material of the catheter shaft while it is in the desired shape to provide the predetermined curve shape 16. In this form, the shape of the polymer material of the catheter shaft 12 may be reset in the presence of the volume of the passive MRI marker forming material to be located on the distal region 14 of the shaft 12. In other manufacturing methods, passive MRI markers on the flexible distal region 14 may be incorporated after the flexible distal region 14 is set to the predetermined curve shape 16. Furthermore, in cases where the catheter shaft 12 includes a proximal shaft portion 34 attached to a distal shaft portion 36 including the distal region 14, a passive MRI marker on the distal region 14 can be attached before or after attaching the distal shaft portion 36 to the proximal shaft portion 34. Similarly, during the attachment of a passive MRI marker to the catheter shaft 12, the cardiac shaft can be positioned through the lumen 24 of the shaft 12 to coincide with one or more locations where the MRI marker will be attached. In cases where the passive MRI marker is attached to the distal region 14 after the distal region has been set to a preset curve shape 16, in some respects, a straight cardiac shaft can be inserted into the distal region 14 to force it into a straight position during the attachment of the passive MRI marker.

[0096] In other embodiments described herein, the interventional medical device may be a guidewire. Figure 14 An example guidewire 100 useful in interventional procedures performed under MRI is shown. Figure 14A longitudinal view is provided, with a portion of the guidewire sheath removed to show the core member therein. The guidewire 100 includes a core member 102 and a sheath 104 disposed on the core member 102. In some preferred forms, the core member 102 is a continuous elongated member having a proximal end 106 and a distal end 108. The cross-section of the core member 102 may have a generally circular outer contour. The core member 102 is preferably completely encapsulated by the sheath 104 such that no part of the core member 102 is exposed to the external environment surrounding the guidewire 100. The cross-section of the sheath 104 may have a generally circular outer contour. The sheath 104 includes a proximal surface 110 proximal to the proximal end 106 of the core member 102, and a distal surface distal to the distal end 108 of the core member 102. In some forms, the sheath 104 may also include a sidewall surface portion 111 adjacent to the proximal surface 110 and appearing on the proximal side of the proximal end 106 of the core member 102 and / or a sidewall surface portion 113 adjacent to the distal surface 112 and appearing on the distal side of the distal end 108 of the core member 102.

[0097] The core component 102 may be formed of any suitable material and typically includes metallic materials, such as metal alloys. Examples of metallic materials considered suitable for forming the core component 102 include, but are not limited to, superelastic metal alloys, including nickel-titanium alloys such as nitinol, superelastic nitinol SE508 straight with a black oxide layer, matte finished nitinol, polished nitinol, nickel-chromium, nickel-cobalt, titanium, nickel oxide, cobalt-chromium-nickel-molybdenum alloys, such as alloys available from Elgiloy Specialty Metals (Elgin, IL) under the trade name Elgiloy, combinations of the metallic materials described herein, and any other metallic materials considered suitable for a particular embodiment. In other forms, the core member 102, or at least the longitudinal portion of which defines the predetermined curved shape 115 as described below, may be formed of a non-metallic material (e.g., a fiber-reinforced polymer material) or of a plurality of shorter segments of metallic material, such as those listed above, which are attached by connectors for electrical insulation from each other, for example as described in U.S. Patent No. 11,724,073, issued August 15, 2023, which is hereby incorporated herein by reference.

[0098] In the illustrated example, the core member 102 is a continuous length of wire with a tapered section along its distal end. The core member 102 may have any suitable longitudinal length, and a skilled technician will be able to select a suitable length for the core member in a guidewire according to a particular embodiment based on various considerations, including the intended use of the guidewire and the characteristics of any bodily blood vessel to which the guidewire is intended to be placed. Examples of lengths considered suitable for the core member 102 in a guidewire include, but are not limited to, lengths equal to, greater than, less than, or about 100 cm, 110 cm, 120 cm, 130 cm, 140 cm, 150 cm, 240 cm, 250 cm, 260 cm, 270 cm, 280 cm, about 50 cm to about 350 cm, about 100 cm to about 280 cm, and about 120 cm to about 260 cm.

[0099] The sheath 104 may be formed of one or more dielectric materials, and will typically be formed of a dielectric polymer material. Examples of suitable dielectric polymer materials include, but are not limited to, thermoformable polymer materials, such as polyamide materials, including nylon materials. These polymer materials are considered desirable, at least because they are capable of melting and flowing between and around components during thermoforming or heat shrinking. Fluoropolymers, such as polytetrafluoroethylene, polyurethane, and other polymer materials may also be used. If desired, additional sheaths or other materials may be applied to the sheath 104. For example, a lubricating material may be applied as an outer coating to the sheath 104. The sheath 104 may have a varied composition along the longitudinal length of the guidewire 100. For example, different polymer compositions may be used at one or both ends relative to the polymer composition present in the sheath located at the longitudinal midpoint of the guidewire. Polymer compositions that provide a more rigid, more durable, or more rigid and more durable sheath may be used at one or both ends to provide resistance to tearing or other damage in the continuous nature of the sheath 104.

[0100] The guidewire 100 includes a flexible distal region 114 having a predetermined curved shape 115. In some forms, the predetermined curved shape 115 may be a curved shape or include a curved shape that continuously bends about a point (the predetermined curved shape in-plane) or an axis (the predetermined curved shape extending out-of-plane). As shown, the predetermined curved shape may be pigtail-shaped. In some forms, the predetermined curved shape 115 may facilitate the catheter's non-invasive positioning through and / or within anatomical structures, such as the chambers of the heart (e.g., the left ventricle) or its associated valvular structures. While in the illustrated embodiment the predetermined curved shape 115 is rotated approximately 540 degrees, it should be understood that in other forms the predetermined curved shape may be rotated to smaller or larger degrees, such as including rotations of at least 45 degrees, at least 90 degrees, at least 180 degrees, at least 270 degrees, or at least 360 degrees. In some typical forms, the predetermined curved shape 115 will be rotated from approximately 270 degrees to approximately 720 degrees. A flexible distal region 114 defines the distal end 103 of the guidewire 100, which appears opposite the proximal end 101 of the guidewire 100. The guidewire 100 has a generally straight proximal portion 105 that is attached to a curved distal portion 107 that defines a predetermined curved shape 115. The longitudinal length of the guidewire 100 defining the curved distal portion 107 is typically in the range of about 1 cm to about 20 cm, more typically about 5 cm to about 15 cm. Additionally or alternatively, in some forms, the predetermined curved shape 115 may have a maximum dimension 115D, considered in a direction perpendicular to the axis of the straight proximal portion 105 of the guidewire 100, in the range of about 0.25 cm to about 8 cm, more typically about 0.5 cm to about 3 cm.

[0101] Guidewire 100 includes a first passive MRI marker 116, a second passive MRI marker 117, and a third passive MRI marker 118, which are longitudinally spaced from each other along guidewire 100. Exemplary guidewire 100 also includes a fourth passive MRI marker 119 positioned on the straight portion 105a at a relatively large longitudinal distance proximal to the next passive MRI marker appearing on guidewire 100 distal to passive MRI marker 119 (providing a proximal reference marker), for example, where this longitudinal distance is at least about two times, or at least about three times, the longitudinal distance between any two adjacent passive MRI markers among a plurality of passive MRI markers distal to passive MRI marker 119 on guidewire 100. For example, such adjacent passive MRI markers may be passive markers 116 and 117, and some form of passive markers 117 and 118, or in some forms they may be passive MRI markers 116 and 117 (where passive MRI marker 118 is not included in the guidewire), or in some forms they may be passive MRI markers 116 and 118 (where passive marker 117 is not included in the guidewire), or in some forms they may be passive MRI markers 117 and 118 (where passive marker 116 is not included in the catheter). The length of the guidewire 100 between passive MRI marker 119 and the next passive MRI marker distal to passive MRI marker 119 may not contain any discrete MRI markers, whether passive or active. In this way, under MRI, the relatively large interval between the corresponding visible artifacts produced by the passive MRI marker 119 and the next appearing discrete MRI marker (e.g., passive MRI marker 116) distal to the passive MRI marker 119 can be observed or tracked, making the marker 119 and its corresponding visible artifacts a useful positional reference for the guidewire 100 when used under MRI. Additionally or alternatively, the passive MRI marker 119 may be configured in some forms to produce visible artifacts under MRI that are different from (e.g., larger in size than (e.g., at least 1.25 times) or alternatively smaller than) the visible artifacts produced by at least the next appearing discrete MRI marker (e.g., passive MRI marker 116) distal to the passive MRI marker 119, and in some forms by the corresponding visible artifacts produced by each of a plurality of passive MRI markers (e.g., passive MRI markers 116, 117, and 118) appearing distal to the passive MRI marker 119. This can also help the passive MRI marker 119 serve as a positional reference for the guidewire 100 and its distal region.

[0102] Although four passive MRI markers are shown in the illustrated embodiment, any suitable number of passive MRI markers may be included on the guidewire disclosed herein, including fewer or more than four. In the illustrated form, guidewire 100 includes passive MRI markers 116 and 119 located on the straight portion 105 of guidewire 100 near the distal region 114, and MRI markers 117 and 188 located on the distal region 114 of the guidewire. Other arrangements are contemplated for other embodiments herein, including in some forms where at least one passive MRI marker is located on the vertical portion 105 (e.g., at least marker 116 or at least marker 119) and at least one passive MRI marker (e.g., at least marker 117 or at least marker 118) or at least two passive MRI markers (e.g., both markers 117 and 118) are located on the distal region 114; or, where at least two passive MRI markers (e.g., both markers 116 and 119) are located on the vertical portion 105 and at least one passive marker (e.g., at least marker 117 or at least marker 118) or at least two passive MRI markers (e.g., both markers 117 and 118) are located on the distal region 114.

[0103] The distal region 114 can be elastically moved from its generally straight configuration, in which it is held (e.g., constrained within the lumen of the catheter), to a predetermined curved shape 115, in a manner similar to that described above. Figures 3 to 6 The discussed deployment involves shaping the generally straight distal region 14 of catheter 10 into a predetermined curved shape 16. During this deployment of the distal region 114, the relative motion and position of passive MRI markers 116, 117, and 118 will correspond, respectively, to the relative motion and position of passive MRI markers 28, 30, and 32 of catheter 10 during the deployment phase (see, for example...). Figures 3 to 6 (and related discussions), these positions and movements do not need to be repeated here, but are fully conceivable for guidewire 100 and other guidewire embodiments herein. Furthermore, in exemplary guidewire 100, from the corresponding Figure 6 In the phase shown, passive MRI marker 118 and its corresponding visible artifact move distally and laterally relative to marker 116 and its visible artifact, and upon reaching the preset curve shape 115, are positioned closer to passive MRI marker 117 and its visible artifact rather than passive MRI marker 116 and its visible artifact.

[0104] Furthermore, in some embodiments, at least one of markers 116, 117, and 118 is configured to produce a visible artifact of a size (e.g., a maximum size) different from the size produced by at least one of markers 116, 117, and 118. This difference can also aid in observing or tracking the shape of the distal region 114 of the guidewire 100. For example, in some guidewire embodiments herein, passive MRI markers 116, 117, and 118 are configured to produce visible artifacts of a size (e.g., a maximum size) corresponding to the combinations described above. Figures 7A to 7D The sizes of passive MRI markers 28, 30, and 32 discussed are produced.

[0105] In some embodiments, when passive MRI markers 116 and 117 are present, guidewire 100 may not contain any discrete MRI markers between them; or when passive MRI markers 117 and 118 are present, no discrete MRI markers are between them; or when passive MRI markers 116 and 118 are present, no discrete MRI markers are between them. In some forms, when all passive MRI markers 116, 117, and 118 are present, the length of guidewire 100 including markers 116, 117, and 118 may not contain any other discrete MRI markers. Furthermore, in embodiments where passive MRI marker 119 is present, when passive MRI markers 119 and 116 are present, guidewire 100 may not contain any discrete MRI markers between them; or when passive MRI marker 116 is absent, no discrete MRI markers are between passive MRI markers 119 and 117.

[0106] Figure 15 A cross-sectional view taken along line 14X-14X is provided, showing the core member 102 surrounded by sheath 104 in the region excluding the guidewire 100 with passive MRI markers. Figure 16A , Figure 17A and Figure 18A Cross-sectional views taken along line 14Y-14Y are provided for various embodiments of guidewire 100 with different passive MRI marker configurations for passive MRI marker 116. Figure 16B , Figure 17B and Figure 18B A corresponding longitudinal view of a segment of guidewire 100 in the region of line 14Y-14Y is shown. Figure 16A and Figure 16BThe view shown depicts an illustrative structure of a passive MRI marker 116. Marker 116 is a plug 120 embedded within a polymeric material of sheath 104. Plug 120 comprises an MRI marker-forming material as described herein. Suitable materials have been found for use in relatively small quantities for these markers. Preferred materials for these purposes are those discussed above for catheter 10. In the illustrated embodiment, plug 120 is entirely within the tubular wall of sheath 104 having a first volume 122 of polymeric material (from which sheath 104 is formed), which appears radially outward of plug 120 and extends to the outer surface of sheath 104, and a second volume 124 of such polymeric material, which appears radially inward of plug 120 and extends to the surface of core member 102. This arrangement can be achieved, for example, through the preparation method embodiments described herein, which involve inserting a plug 120 into an opening in the wall of a sheath 104, the opening extending from the outer surface of the wall and only partially penetrating the thickness of the wall, and filling the opening with a molten volume of polymer material (from which the sheath 104 is formed) and forming a new outer surface portion of the sheath 104 above the plug 120. For these purposes, the polymer material can be heated before, during, and / or after the insertion of the plug 120, for example by ultrasonic or other means, to melt, flow, and fill the opening and surround the plug 120, and then cooled (e.g., passively or actively) to solidify. The plug 120 can be mounted to a heated end of a probe, such as an ultrasonically heated end, for insertion into the wall of the sheath 104. The probe can heat the plug 120 and the polymer material during insertion, and can also heat the polymer material after the plug 120 has deposited in the wall of the sheath 104 and during its removal from the polymer material. This facilitates the flow of polymer material and its envelopment of the stopper 120, filling the stopper 120 with a first volume 122 of polymer material. This technique facilitates self-healing of the polymer material as a new outer surface of the sheath forms over the stopper 120. The stopper 120 is embedded in the sheath 104, and the sheath 104 encapsulates the core member 102 as described above. Although in the illustrated embodiment the stopper 120 is positioned only partially through the wall thickness of the sheath 104, in other forms the stopper 120 may be inserted completely through the wall thickness of the sheath 104 and contact the core member 102, and the volume 122 of polymer material may still extend between the stopper 120 and the outer surface of the sheath 104.

[0107] Figure 17A and Figure 17BThe view shown depicts another illustrative structure of a passive MRI marker 116. In this form, marker 116 is a plug 130 embedded within the wall of a sheath 104. Unlike the polymeric material from which the walls of the sheath 104 are formed, a solid filler material 132 appears radially outward of the plug 130 and provides a covering surface 134 of the filler material, which in some forms may be substantially flush with the adjacent surface of the sheath 104. The filler material 132 may be, for example, an adhesive, such as a polymeric adhesive. Like the plug 120 discussed above, the plug 130 comprises the MRI marker-forming material discussed herein.

[0108] Figure 18A and Figure 18B A view depicting another illustrative structure of a passive MRI marker 116 is provided. In this form, the marker 116 is a strip 140 of MRI marker-forming material trapped between the outer surface of the core member 102 and the inner surface of the sheath 104. The strip 140 preferably has a thickness not exceeding about 0.1 mm and is typically in the range of about 0.01 mm to about 0.05 mm, or about 0.01 mm to about 0.03 mm, or about 0.01 mm to about 0.02 mm. In some forms, the strip 140 of MRI marker-forming material is at least adhered to the outer surface of the core member 102. In some forms, the strip 140 may comprise a matrix material in which particles of the MRI marker-forming material are dispersed. In fabricating this arrangement of the marker 116, in some forms, the strip 140 may be formed by curing a flowable material applied to the outer surface of the core member. The flowable material comprises precursors and particles of the matrix material and cures upon curing to form the strip 140. The sheath 104 may then be applied to the core member 102. In other forms, the strip 140 may include, for example, metal plated (e.g., electroplated) onto the outer surface of the core member 102 before the sheath 104 is applied to the core member 102. Nickel plating is particularly preferred for these purposes. In other forms, the strip 90 may be formed of a solid layer material, such as a metal foil, like nickel foil, which is placed on the outer surface of the core member 102 and potentially adhered (e.g., with an adhesive) to the outer surface before the sheath 104 is applied to the core member 102.

[0109] Figure 19A and Figure 19BA view is provided illustrating another illustrative structure of a passive MRI marker 116. In this form, the marker 116 is a plug 150 within the wall of a sheath 104. The plug 150 is formed of particulate MRI marker forming material 152 dispersed in a matrix material 154, such as a polymer matrix material (which may be the same as or different from the polymer material forming the sheath 104). The plug 150 provides a surface 156 that is flush with the adjacent surface of the sheath 104. This arrangement of the marker 116 can be produced by filling the openings created in the wall of the sheath 104 with a flowable material comprising a precursor (e.g., an adhesive) of the particulate material 152 and the matrix material 154, and curing the precursor material to form the matrix material 154.

[0110] Figure 20A and Figure 20B A view depicting another illustrative structure of a passive MRI marker 116 is provided. In this form, the marker 116 is a strip 160 of MRI marker-forming material extending around the outer periphery of a sheath 104 and providing an outer strip surface 162 on the sheath 104. The strip 160 may include a matrix material 164 in which particles 166 of the MRI marker-forming material are dispersed. In some aspects, the strip 160 may be formed by curing a flowable material applied to an axis, the flowable material comprising a precursor (e.g., an adhesive) of the matrix material 164 and particles 166, for example, wherein the flowable material has the properties of an MRI marker-forming ink, which may further include a colorant selected to provide contrast between adjacent surfaces of the strip 160 and the sheath 104.

[0111] While the above discussion of passive MRI marker configurations specifically relates to passive MRI marker 116 of guidewire 100, it should be understood that other passive MRI markers of guidewire 100, such as passive markers 117, 118, and 119, may have the same characteristics. Similarly, it should be understood that different passive MRI markers on guidewire 100 may have different configurations, such as any combination including those discussed herein.

[0112] Similarly, while some of the discussions above pertain to the presence of MRI marker-forming material in a strip extending circumferentially around the core member 102 or sheath 104 of the guidewire 100, it should be understood that in other embodiments, the MRI marker-forming material in question may be or may be present in a layer that does not extend completely around the periphery of the core member 102 or sheath 104. These and other variations are considered to be within the scope of this disclosure.

[0113] As described herein, the distal region 114 of guidewire 100 has a predetermined curve shape 115. The polymer sheath 104 within the predetermined curve shape 115 may have an innermost portion 115' or "inner ridge" extending along a line extending along a first curve, and an outermost portion 115" or "outer ridge" extending along a line extending along a second curve opposite to the first curve on the sheath 104. Similarly, as described herein, in some forms, the MRI marker may be a plug of MRI marker-forming material embedded in the wall of the polymer sheath 104 of guidewire 100. In some preferred forms, when present in the distal region of guidewire 100 having the predetermined curve shape 115, such plug-type markers will be positioned on the periphery of the sheath 104 so as not to overlap with the innermost portion 115' and / or the outermost portion 115" , for example, in some forms, so as to surround the outer periphery of the sheath 104. At least approximately 15 degrees, or at least approximately 30 degrees around the outer perimeter of the sheath 104, circumferentially spaced from the innermost portion 115' and / or the outermost portion 115”. This position of the plug-type passive MRI marker may be selected to provide embodiments that apply relatively low stress to the marker during movement of the distal region 114 between the preset curved shape 115 and a straightened state, for example, where the marker neither overlaps with the inner ridge nor its outer ridge of the preset curved shape 115. In some guidewire 100 configurations, this position of the plug-type MRI marker may help maintain the curvature characteristics of the preset shape 115, for example, when the outermost portion 115” of the preset shape 115 is pressed against the patient's anatomical surface while the distal region 114 is in the preset curved shape 115.

[0114] The advantage is that the above combination Figures 16A to 20B The marker configuration discussed, or other markers described herein, may appear in a relatively small area of ​​the guidewire 100. For example, such markers may appear within a longitudinal length not exceeding 10 mm or 5 mm, and typically within the range of 0.2 to 5 mm; and / or, in the case of plug-type markers or some non-peripheral material layer markers, they may have a width perpendicular to the axis of the sheath 104, which does not exceed approximately 90%, or approximately 80%, or approximately 70% of the corresponding width of the sheath 104, or is within the range of approximately 10% to approximately 100%, or approximately 10% to approximately 70% of the corresponding width of the sheath 104. Markers comprising plugs of the MRI marker-forming material as described above are particularly advantageous for application within such widths and such longitudinal lengths.

[0115] In some embodiments, the core member 102 may include features that aid in detecting a breach in the continuity of the sheath 104, which can help ensure the use of a guidewire with a truly continuous sheath 104. For example, the core member 102 may include a sheath with a high-contrast color on its surface, disposed beneath the sheath 104. This high-contrast color of the underlayer sheath is relative to any color of the sheath 104. For example, if the sheath 104 is dark, such as black or gray, a light-colored underlayer sheath, such as a yellow sheath, provides high-contrast color that, if visible during inspection before use of the guidewire, can alert the user to a breach in the continuity of the sheath 104, thereby allowing the user to assess whether the guidewire should be used for the intended procedure. Furthermore, the core member 102 may include a coating that responds to exposure to external substances other than the sheath 104, such as water. For example, the core member 102 may include a coating that changes color if it comes into contact with an external substance, such as water. The color change may be visible under ambient light or another wavelength, such as ultraviolet light or another wavelength. When the core component includes this coating, the appropriate color change of one or more guidewires can be examined at an appropriate light wavelength and incorporated into the method of manufacturing one or more guidewires.

[0116] Additional embodiments herein relate to interventional medical systems including a catheter and a guidewire, the guidewire extending through the lumen of the catheter to position a distal region of the guidewire beyond the distal end of the catheter, and relate to guidewires and catheters that can be used in such systems. The distal region of the guidewire has at least a first guidewire-positioned passive MRI marker configured to produce a visible artifact of the first guidewire-positioned guidewire with a maximum size. The catheter has at least a first catheter-positioned passive MRI marker configured to produce a visible artifact of the first catheter-positioned catheter with a maximum size. The maximum size of the visible artifact of the first guidewire-positioned catheter is greater than the maximum size of the visible artifact of the first catheter-positioned catheter, and substantially larger in a particularly advantageous form, as described below.

[0117] Now for reference Figure 21 and Figure 22 , Figure 21 A partial cross-sectional side view of an illustrative embodiment of the intervention system 170 described herein is shown, and Figure 22The diagram also shows a corresponding view graphically depicting the visible artifacts produced by the combined passive MRI markers under MRI. System 170 includes a catheter 172 and a guidewire 174, the guidewire extending through the lumen of the catheter to position a distal region 176 of the guidewire 174 beyond the distal end 178 of the catheter 172. The distal region 176 includes the distal end 180 of the guidewire 174. In some forms, the distal region 176 may have a longitudinal length of at least about 5 cm, or at least about 7 cm, or at least about 10 cm, or in the range of about 5 to about 30 cm, or in the range of about 7 cm to 20 cm. The distal region 176 of the guidewire 174 includes a passive MRI marker 182 positioned by the first guidewire. The catheter 172 includes a passive MRI discrete marker 184 positioned by the first catheter. Figure 22 As can be seen in the MRI, the passive MRI marker 182 for first guidewire positioning is configured to generate discrete visible artifacts 182A for first guidewire positioning, and the passive MRI marker 184 for first catheter positioning is configured to generate discrete visible artifacts 184A for first catheter positioning, wherein the maximum size of visible artifact 182A is larger than the maximum size of visible artifact 184A. In a preferred embodiment, the maximum size of the discrete artifact 182A for first guidewire positioning will be at least about 1.3 times, or at least about 2 times, the maximum size of the discrete artifact 184A for first catheter positioning, and in some respects, within the range of about 1.3 times to about 3 times, or about 1.5 times to about 3 times, the maximum size of the discrete artifact 184A for first catheter positioning. In some embodiments, the passive MRI marker 184 for first catheter localization may be the most distal discrete MRI marker on catheter 172, and / or the passive MRI marker 182 may be the most proximal discrete MRI marker on the distal region 176 of guidewire 174, and in some variations, it may be the most proximal discrete MRI marker on guidewire 174. Similarly, in some forms, the maximum size of the artifact 182A for first guidewire localization may be larger than the maximum size produced by any discrete MRI marker on catheter 172 within 5 cm or 10 cm of its distal end 178, or in some forms, larger than the maximum size produced by any discrete MRI marker throughout catheter 172.

[0118] In some configurations, where the marker 182 for first guidewire positioning is a discrete MRI marker on the nearest side of guidewire 174, system 170 may be configured such that the markers 182 are longitudinally spaced along system 170 distal to the distal end 178 of catheter 172 by a longitudinal distance D3 of at least about 5 cm, or at least about 7 cm, or at least about 10 cm, or in the range of about 5 to about 30 cm, or in the range of about 7 cm to 20 cm. Additionally or alternatively, where the passive MRI marker 184 for first catheter positioning is the most distal discrete MRI marker on catheter 172 and the passive MRI marker for first guidewire positioning is the nearest discrete MRI marker on guidewire 174, the passive MRI marker 184 is spaced longitudinally from the passive MRI marker 182 along system 170 by a longitudinal distance D4 not exceeding approximately 1.5 times, or not exceeding approximately 1.25 times, or not exceeding 1.1 times the longitudinal distance D3. It should be understood that this arrangement includes embodiments in which longitudinal distances D3 and D4 are the same (where MRI marker 184 may be located at the distal end 178 of catheter 172).

[0119] In some embodiments, catheter 172 and / or guidewire 174 may have one or more additional passive MRI markers. For example, guidewire 174 may have a second guidewire-positioned passive MRI marker 186 located distal to MRI marker 182 and configured to produce discrete visible artifacts 186A, which, in the case of a straight configuration of distal region 126, may be spaced apart from visible artifact 182A, or may partially overlap with visible artifact 182A as shown; and / or, catheter 172 may have a second catheter-positioned passive MRI marker 188 located proximal to MRI marker 184 and configured to produce discrete visible artifacts 186A, which, in the case of a straight configuration of catheter 172, are preferably, but not necessarily, spaced apart from visible artifact 184A. In some aspects, passive MRI markers on catheter 172, such as markers 184 and 188, may have a combination of Figures 8A to 12B Any of the features shown and discussed for marker 28, and / or in some respects, passive MRI markers on guidewire 174, such as markers 182 and 186, may have a combination Figures 16A to 20B Any of the features shown and discussed for marker 116.

[0120] In use, during the movement of catheter 172 proximally and / or distally along guidewire 174 while guidewire 174 remains in a fixed position within the patient, passive MRI markers 182 and / or 186 positioned by the guidewire provide a distal location reference. For example, this procedure can be performed to treat a patient within a target region 190, such as for diagnostic and / or therapeutic purposes, the target region being, in some forms, within the patient's vascular system. For example, the treatment may include deploying an implant (such as a stent or stent valve) carried by the catheter into the target region, and / or inflating a balloon mounted on catheter 172 within the target region, for example, to dilate a narrowed segment of blood vessel in the target region. Guidewire 174 may be percutaneously introduced into the patient and guided through and across the target region 190 to position markers 182 and / or 186 beyond the target region 190. Catheter 172 may be percutaneously introduced onto guidewire 174 (where the guidewire extends through the lumen of catheter 172) and advanced along guidewire 174 into the target region 190. With guidewire 174 held in a fixed position within the patient's body, catheter 172 can be used to treat the patient within target region 190. During treatment, MRI image data can be acquired and used to generate and visually display (e.g., on an electronic display monitor or other electronic display) real-time or near-real-time MRI images, such as two-dimensional MRI image slices, including the location of the target region 190 with catheter 172 and guidewire positioning markers 182 and / or 184. The image data can be represented, and the images can display artifacts 182A and / or 184A generated by guidewire positioning markers 182 and / or 184, and artifacts 184A and / or 188A generated by catheter positioning MRI markers 184 and / or 188. Continuous visual observation or tracking of the guidewire positioning artifacts 182A and / or 186A within the patient's body can provide a reference for determining that the catheter 172 and its visually observed / tracked catheter positioning artifacts 184A and / or 188A remain within the target area 190 (e.g., providing an indication that the system 170 as a whole has not shifted within the patient's body). During a given procedure on the patient, the image data and displayed images can represent various regions within the target area 190, such as tissue planes, and can be captured at various angles to the volume of the target area 190 or at various heights / depths within the volume of the target area. This can provide improved determination of the relative position of the patient's anatomical features of interest and the catheter 172, for example, through visual observation / tracking of the catheter positioning artifacts 184A and / or 188A. Similarly, the patient's anatomical structures in the target area and surrounding areas can well align the distal region 176 of the guidewire 174 to extend in the deflection direction relative to the distal region of the catheter 172 involved in the procedure.The relatively large size of artifacts 182A and / or 186A helps ensure that MRI image data and MRI images (e.g., two-dimensional image slices) acquired to represent or show various tissue planes or other segments within the volume of the target region 190 will include artifacts 182A and / or 186A. In this way, during the procedure, MRI markers 182 and / or 186, along with their larger artifacts 182A and / or 186A, can serve as highly advantageous locational references outside the target region 190. Simultaneously, the relatively small catheter positioning artifacts 184A and / or 188A within the target region 190 minimize the degree to which interesting patient anatomical features within the target region 190 are obscured.

[0121] List of selected embodiments

[0122] The following clauses provide a non-limiting list of some embodiments disclosed herein. It should be understood that one, two, or more features disclosed above may be combined with the embodiments listed below to provide further specific embodiments of the disclosure herein, and each alternative scope or other feature is considered a separately disclosed embodiment when alternative scopes or other features are expressed in the listed embodiments.

[0123] Example 1. An interventional medical device useful in magnetic resonance imaging (MRI) guided procedures, comprising:

[0124] An elongated member configured for insertion into a patient and having a flexible distal region having a predetermined curved shape in a relaxed state, but which can be elastically configured into a second shape by applying force, the second shape being different from the predetermined curved shape.

[0125] A first passive MRI marker, located at a first position along the elongated member, is configured to produce a first artifact under the MRI.

[0126] A second passive MRI marker is located at a second location distal to the first location and along the flexible distal region, the second passive MRI marker being configured to produce a second artifact under the MRI.

[0127] When the flexible distal region moves from the second shape to the preset curved shape, the change in the relative position of the first passive MRI marker with respect to the second passive MRI marker is visually detectable under MRI.

[0128] Example 2. The interventional medical device according to Example 1, wherein in the preset curved shape, the flexible distal region has a longitudinal axis extending in a plane.

[0129] Example 3. An interventional medical device according to Example 1 or 2, wherein the first artifact has a first maximum size, the first maximum size being approximately 1.5 to approximately 50 times the first outer diameter of the first longitudinal segment of the catheter shaft on which the first passive MRI marker appears, and the second artifact has a second maximum size, the second maximum size being approximately 1.5 to approximately 50 times the second outer diameter of the second longitudinal segment of the catheter shaft on which the second passive MRI marker appears; and, optionally, wherein the first artifact has a maximum size, the maximum size being approximately 2 to approximately 20 times the first outer diameter, and the second artifact has a second maximum size, the second maximum size being approximately 2 to approximately 20 times the second outer diameter.

[0130] Example 4. An interventional medical device according to any one of Examples 1 to 3, wherein the first artifact and the second artifact have a minimum size, the minimum size being at least about 2 times, or at least about 3 times, larger than the maximum diameter of the flexible distal region of the elongated body.

[0131] Example 5. An interventional medical device according to any one of Examples 1 to 4, wherein when the flexible distal region moves between the second shape and the preset curved shape, the second passive MRI marker moves laterally relative to the first passive MRI marker.

[0132] Example 6. An interventional medical device according to any one of Examples 1 to 5, wherein when the flexible distal region moves between the second shape and the preset curved shape, the second passive MRI marker moves closer to the first passive MRI marker. Optionally, wherein the second shape is a straight state of the flexible distal region, and when the distal region is in the preset curved shape, the distance between the first passive MRI marker and the second passive MRI marker does not exceed approximately 90% of the distance between the first passive MRI marker and the second passive MRI marker when the distal region is in the straight state, and preferably does not exceed approximately 50% of the distance between the first passive MRI marker and the second passive MRI marker when the distal region is in the straight state.

[0133] Example 7. An interventional medical device according to any one of Examples 1 to 6, further comprising a third passive MRI marker, wherein the third passive MRI marker is longitudinally located proximal to the second passive MRI marker along the distal region.

[0134] Example 8. The interventional medical device according to Example 7, wherein when the flexible distal region is in the second shape, the second passive MRI marker is distal to the third passive MRI marker, and wherein when the flexible distal region is in the preset curved shape, the second passive MRI marker is proximal to the third passive MRI marker.

[0135] Example 9. An interventional medical device according to any one of Examples 1 to 8, wherein the first passive MRI marker is located on the elongated member at a position proximal to the flexible distal region.

[0136] Example 10. The interventional medical device according to Example 9, wherein the first passive MRI marker is located within approximately 2 cm proximal to the distal region.

[0137] Example 11. An interventional medical device according to any one of Examples 1 to 8, wherein the first passive MRI marker is located on the flexible distal region at a position proximal to the second passive MRI marker.

[0138] Example 12. The interventional medical device according to Example 11, wherein when the flexible distal region is in the second shape, the second passive MRI marker is distal to the first passive MRI marker, and wherein when the flexible distal region is in the preset curved shape, the second passive MRI marker is proximal to the first passive MRI marker.

[0139] Example 13. An interventional medical device according to any one of Examples 1 to 12, wherein the device is a catheter.

[0140] Example 14. The interventional medical device according to Example 13, wherein the catheter has at least one side port.

[0141] Example 15. The interventional medical device according to Example 14, wherein the at least one side port is located distal to the first passive MRI marker, and the elongated member does not contain any side ports located proximal to the first passive MRI marker.

[0142] Example 16. An interventional medical device according to any one of Examples 13 to 15, wherein the first passive MRI marker and the second passive MRI marker each comprise a passive MRI marker forming material embedded in the wall of the catheter.

[0143] Example 17. The interventional medical device according to Example 16, wherein the wall of the catheter comprises a first volume of polymer material forming the wall located radially inside the passive MRI marker forming material and between the passive MRI marker forming material and the catheter lumen surface defined by the first volume of polymer material.

[0144] Example 18. An interventional medical device according to any one of Examples 13 to 17, wherein the flexible distal region is formed of a thermoplastic elastomer material.

[0145] Example 19. An interventional medical device according to any one of Examples 1 to 12, wherein the device is a guidewire.

[0146] Example 20. The interventional medical device according to Example 19, wherein the guidewire includes a core component and a polymer sheath encapsulating the core component.

[0147] Example 21. The interventional medical device according to Example 20, wherein the core component is a single continuous length of metal wire.

[0148] Example 22. The interventional medical device according to Example 21, wherein the metal wire is formed of a superelastic metal alloy.

[0149] Example 23. The interventional medical device according to Example 22, wherein the superelastic metal alloy is nickel-titanium alloy.

[0150] Example 24. An interventional medical device according to any one of Examples 20 to 23, wherein the polymer sheath is formed of a polyamide polymer.

[0151] Example 25. An interventional medical device according to any one of Examples 20 to 24, wherein the first passive MRI marker and the second passive MRI marker each comprise a passive MRI marker forming material between the polymer sheath and the core member.

[0152] Example 26. The interventional medical device according to Example 25, wherein the passive MRI marker forming material is a metal layer plated on the outer surface of the core member, optionally wherein the metal layer is a nickel layer.

[0153] Example 27. An interventional medical device according to any one of Examples 20 to 24, wherein the first passive MRI marker and the second passive MRI marker each comprise a passive MRI marker forming material embedded in the wall of the polymer sheath.

[0154] Example 28. An interventional medical device according to any one of Examples 1 to 27, wherein the preset curve shape is rotated by at least about 90 degrees, at least about 180 degrees, or at least about 360 degrees.

[0155] Example 29. The interventional medical device according to Example 28, wherein the preset curve shape is rotated by no more than about 720 degrees.

[0156] Example 30. The interventional medical device according to Example 28 or 29, wherein the second passive MRI marker appears at a position where the preset curve shape has been rotated between approximately 65 degrees and approximately 115 degrees.

[0157] Example 31. An interventional medical device according to any one of Examples 1 to 30, wherein the first passive MRI marker and the second passive MRI are each located within a longitudinal length of the elongated member of not more than about 10 mm, or not more than about 5 mm, or in the range of about 0.2 to about 5 mm.

[0158] Example 32. The interventional medical device according to Example 31, wherein the first passive MRI marker and the second passive MRI marker each include a passive MRI marker forming material layer, optionally wherein the layer is in the form of a circumferential band.

[0159] Example 33. The interventional medical device according to Example 32, wherein the first passive MRI marker and the second passive marker each include a plug of passive MRI marker forming material, optionally wherein the plug does not overlap with the innermost portion of the elongated member, wherein the innermost portion extends along a line extending along a first curve of the preset curve shape when the distal region is in the preset curve shape, and the plug also does not overlap with the outermost portion of the elongated member, wherein the outermost portion extends along a line extending along a second curve when the distal region is in the preset curve shape, the second curve being opposite to the first curve.

[0160] Example 34. An interventional medical device according to any one of Examples 1 to 32, wherein the first passive MRI marker and the second passive MRI marker appear within a width across the elongated member such that the width does not exceed approximately 70% of the outer width of the elongated member at the respective positions of the first passive MRI marker and the second passive MRI marker.

[0161] Example 35. An interventional medical device according to any one of Examples 1 to 34, wherein the first passive MRI marker and the second passive MRI marker each include (i) an MRI marker forming material, the volume of which does not exceed 5 mm. 3 or not exceeding 3 mm 3 or not exceeding 1 mm 3 or not exceeding 0.1 mm 3 In each of these aspects, the volume can be at least 0.00005 mm. 3 or at least about 0.0001 mm 3 ; or (i) an MRI marker forming material having a magnetic susceptibility of at least about 1 and a volume not exceeding 0.1 mm. 3 or in 0.00001 mm 3 Up to 0.1 mm 3 Within the range, or 0.00005 mm 3 Up to 0.02 mm 3 Within the range.

[0162] Example 36. An interventional medical device according to any one of Examples 1 to 35, wherein the first passive MRI marker and the second passive MRI marker each comprise an MRI marker forming material, the MRI marker forming material having a magnetic susceptibility of at least about 500 ppm, or at least about 2000 ppm, or in the range of about 500 ppm to about 1000, or in the range of about 7000 ppm to about 1000.

[0163] Example 37. An interventional medical device according to any one of Examples 1 to 36, wherein the first passive MRI marker and the second passive MRI marker each include an MRI marker forming material selected from nickel, nickel alloys, cobalt, cobalt alloys, iron, and iron alloys.

[0164] Example 38. An interventional medical device according to any of Examples 1 to 37, further comprising a proximal reference passive MRI marker located on the elongated member proximal to the first passive MRI marker, optionally wherein the proximal reference passive MRI marker is configured to produce artifacts (i) having a maximum size greater than the maximum size of the first passive MRI marker and the maximum size of the second passive MRI marker, or (ii) having a maximum size greater than the maximum size of any discrete MRI marker distal to the proximal reference passive MRI marker.

[0165] Example 39. The interventional medical device according to Example 38, wherein:

[0166] The first passive MRI marker is longitudinally adjacent to the second passive MRI marker and located at a first longitudinal distance from the second passive marker, wherein the proximal reference passive MRI marker is located at a second longitudinal distance from the first passive MRI marker, and wherein the second longitudinal distance is at least twice the first longitudinal distance; and / or

[0167] The proximal reference passive MRI marker is configured to produce artifacts, the maximum size of which is at least about 1.25 times the maximum size of the first passive MRI marker and the maximum size of the second passive MRI marker.

[0168] Example 40. An interventional medical device according to any one of Examples 1 to 39, wherein:

[0169] The first passive MRI marker and the second passive MRI marker are configured to produce artifacts of different sizes; or

[0170] The first passive MRI marker and the second passive MRI marker are formed from the same passive MRI marker forming material, but the passive MRI marker forming material has different volumes; or

[0171] The first passive MRI marker is formed from a first passive MRI marker forming material, and the second passive MRI marker is formed from a second passive MRI marker forming material, wherein the magnetic susceptibility of the first passive MRI marker forming material is different from the magnetic susceptibility of the second passive MRI marker forming material.

[0172] Example 41. An interventional system useful in medical procedures guided by magnetic resonance imaging (MRI) under a main magnetic field strength, comprising:

[0173] A first elongated medical device for treating a target area of ​​a patient using a distal region of the first elongated medical device, the first elongated medical device having a distal end, the first elongated medical device including a first passive MRI marker; and

[0174] A second elongated medical device is positioned through the lumen of the first elongated medical device to position a distal region of the second elongated medical device distal to the distal end of the first elongated medical device, the distal region of the second elongated medical device including a first passive MRI marker.

[0175] The first passive MRI marker of the first elongated medical device is configured to produce a first medical device localization artifact with the largest size under the MRI.

[0176] The first passive MRI marker of the second elongated medical device is configured to produce a second medical device localization artifact of maximum size under the MRI; and

[0177] The maximum size of the second medical device positioning artifact is greater than the maximum size of the first medical device positioning artifact.

[0178] Example 42. The interventional system according to Example 41, wherein the first elongated medical device is a catheter.

[0179] Example 43. An interventional system according to Example 41 or 42, wherein the second elongated medical device is a guidewire.

[0180] Example 44. The interventional system according to Example 43, wherein the guidewire includes a core member and a polymer sheath encapsulating the core member.

[0181] Example 45. The intervention system according to Example 44, wherein the core component is a single continuous length of metal wire.

[0182] Example 46. The intervention system according to Example 45, wherein the metal wire is formed of a superelastic metal alloy.

[0183] Example 47. The intervention system according to Example 46, wherein the superelastic metal alloy is nickelitanol.

[0184] Example 48. An interventional system according to any one of Examples 44 to 47, wherein the polymer sheath is formed of a polyamide polymer.

[0185] Example 49. An interventional system according to any one of Examples 44 to 48, wherein the first passive MRI marker and the second passive MRI marker each comprise a passive MRI marker forming material between the polymer sheath and the core member.

[0186] Example 50. The interventional system according to Example 49, wherein the passive MRI marker forming material is a metal layer plated on the outer surface of the core member, optionally wherein the metal layer is a nickel layer.

[0187] Example 51. An interventional system according to any one of Examples 44 to 48, wherein the first passive MRI marker and the second passive MRI marker each comprise a passive MRI marker forming material embedded in the wall of the polymer sheath.

[0188] Example 52. An interventional system according to any one of Examples 41 to 51, wherein the distal region of the second elongated medical device has a longitudinal length of at least about 5 cm, or at least about 7 cm, or at least about 10 cm, or in the range of about 5 to about 30 cm, or in the range of about 7 cm to 20 cm.

[0189] Example 53. An interventional system according to any of Examples 41 to 52, wherein the first passive MRI marker of the second elongated medical device is a proximal discrete MRI marker in the distal region of the second elongated medical device, and wherein the system is locatable to a first configuration in which the first passive MRI marker of the second elongated medical device is longitudinally spaced by a first distance distal to the distal end of the first elongated medical device, wherein the first distance is at least about 7 cm, or at least about 10 cm, or in the range of 7 to 30 cm.

[0190] Example 54. The interventional system according to Example 53, wherein the first passive MRI marker of the first elongated medical device is the most distal discrete MRI marker of the first elongated medical device, and wherein in the first configuration, the first passive MRI marker of the second medical device is longitudinally spaced by a second distance distal to the first passive MRI marker of the first elongated medical device, wherein the second distance does not exceed approximately 1.25 times the first distance.

[0191] Example 55. An interventional system according to any one of Examples 41 to 54, wherein the first medical device is a catheter, and wherein the first passive MRI marker comprises a passive MRI marker forming material embedded in the wall of the catheter.

[0192] Example 56. The interventional system according to Example 55, wherein the wall of the catheter comprises a first volume of polymer material forming the wall located radially inside the passive MRI marker forming material and between the passive MRI marker forming material and the catheter lumen surface defined by the first volume of polymer material.

[0193] Example 57. The intervention system according to Example 56, wherein the polymer material comprises a thermoplastic elastomer material.

[0194] Example 58. An interventional system according to any one of Examples 41 to 57, wherein the first passive MRI marker and the second passive MRI marker each comprise (i) an MRI marker forming material, the volume of which does not exceed 5 mm. 3 or not exceeding 3 mm 3 or not exceeding 1 mm 3 or not exceeding 0.1 mm 3 In each of these aspects, the volume can be at least 0.00005 mm. 3 or at least about 0.0001 mm 3 ; or (i) an MRI marker forming material having a magnetic susceptibility of at least about 1 and a volume not exceeding 0.1 mm. 3 or in 0.00001 mm 3 Up to 0.1 mm 3 Within the range, or 0.00005 mm 3 Up to 0.02 mm 3 Within the range.

[0195] Example 59. An interventional system according to any one of Examples 41 to 58, wherein the first passive MRI marker and the second passive MRI marker each comprise an MRI marker forming material, the MRI marker forming material having a magnetic susceptibility of at least about 500 ppm, or at least about 2000 ppm, or in the range of about 500 ppm to about 1000, or in the range of about 7000 ppm to about 1000.

[0196] Example 60. An interventional system according to any one of Examples 41 to 59, wherein:

[0197] The first passive MRI marker and the second passive MRI marker each include an MRI marker forming material, wherein the MRI marker forming material is selected from nickel, nickel alloys, cobalt, cobalt alloys, iron, and iron alloys; or

[0198] The first passive MRI marker and the second passive MRI marker are configured to produce visible artifacts of different sizes; or

[0199] The first passive MRI marker and the second passive MRI marker are formed from the same passive MRI marker forming material, but the passive MRI marker forming material has different volumes; or

[0200] The first passive MRI marker is formed from a first passive MRI marker forming material, and the second passive MRI marker is formed from a second passive MRI marker forming material, wherein the magnetic susceptibility of the first passive MRI marker forming material is different from the magnetic susceptibility of the second passive MRI marker forming material.

[0201] Example 61. An interventional medical device useful under magnetic resonance imaging (MRI), comprising:

[0202] An elongated member configured for insertion into a patient and having a flexible distal region having a predetermined curved shape in a relaxed state, but elastically configurable into a straight state when force is applied.

[0203] A first passive MRI marker is located at a first position along the elongated member;

[0204] A second passive MRI marker is located at a second position along the elongated member, the second position being longitudinally spaced from the first position; and

[0205] in:

[0206] (i) The first passive MRI marker is proximal to the flexible distal region having the preset curved shape, and the second passive MRI marker is longitudinally located distal to the first passive MRI marker and on the flexible distal region having the preset curved shape, wherein when the distal region is in the preset curved shape, the second passive MRI marker is closer to the first passive marker than when the distal region is in the straight state; or

[0207] (ii) Both the first passive MRI marker and the second passive MRI marker are located on the flexible distal region having the preset curved shape, and are configured to produce corresponding discrete visible artifacts under MRI at a main magnetic field strength of at least one of 0.55T, 1.5T, and 3T when the flexible distal region is in the straight state and the preset curved shape; or

[0208] (iii) One of the first passive MRI marker or the second passive MRI marker is positioned on the distal region to mark the distal position of the preset curve shape.

[0209] Example 62. The interventional medical device according to Example 61, wherein the first passive MRI marker is located proximally to the flexible distal region having a preset curved shape, and the second passive MRI marker is located on the flexible distal region having a preset curved shape, wherein when the distal region is in the preset curved shape, the second passive MRI marker is closer to the first passive marker than when the distal region is in the straight state.

[0210] Example 63. The interventional medical device according to Example 62, wherein when the distal region is in the preset curved shape, the distance between the first passive MRI marker and the second passive MRI marker does not exceed about 90% of the distance between the first passive MRI marker and the second passive MRI marker when the distal region is in the straight state, and optionally, wherein the first passive MRI marker is longitudinally positioned within 2 cm of the flexible distal region.

[0211] Example 64. An interventional medical device according to any one of Examples 61 to 63, further comprising a third passive MRI marker; and, optionally, wherein at least one of the first, second, and third passive MRI markers is configured to produce a visible artifact, the size of which is different from at least one other passive MRI marker among the first, second, and third passive MRI markers.

[0212] Example 65. The interventional medical device according to Example 64, wherein the third passive MRI marker is located on the distal region and is longitudinally positioned between the first passive MRI marker and the second passive MRI marker along the elongated member.

[0213] Example 66. The interventional medical device according to Example 65, wherein when the flexible distal region is in the straight state, the second passive MRI marker is distal to the third passive MRI marker, and wherein when the flexible distal region is in the preset curved shape, the second passive MRI marker is proximal to the third passive MRI marker.

[0214] Example 67. An interventional medical device according to Example 65 or 66, wherein when the distal region is in the preset curved shape, the second passive MRI marker is closer to the first passive marker than when the distal region is in the straight state.

[0215] Example 68. The interventional medical device according to Example 62, wherein the first passive MRI marker and the second passive MRI marker are both on the flexible distal region having the preset curved shape and are longitudinally spaced apart from each other, and are configured to produce corresponding discrete visible artifacts under MRI at a main magnetic field strength of at least one of 0.55T, 1.5T and 3T when the flexible distal region is in the straight state and the preset curved shape.

[0216] Example 69. An interventional medical device according to Example 68, wherein the second passive MRI marker is located longitudinally proximal to the first passive MRI marker in the flexible distal region, and wherein when the flexible distal region is in the straight state, the first passive MRI marker is located distal to the second passive MRI marker, and when the flexible distal region is in the preset curved shape, the first passive MRI marker is located proximal to the second passive MRI marker.

[0217] Example 70. The interventional medical device according to Example 68 or 69 further includes a third passive MRI marker; and, optionally, at least one of the first, second, and third passive MRI markers is configured to produce a visible artifact, the size of which is different from at least one other passive MRI marker among the first, second, and third passive MRI markers.

[0218] Example 71. The interventional medical device according to Example 70, wherein the third passive MRI marker is longitudinally positioned within approximately 2 cm of the proximal end of the flexible distal region.

[0219] Example 72. An interventional medical device according to any one of Examples 69 to 71, wherein when the flexible distal region is in the preset curved shape, the distance between the first passive MRI marker and the third passive MRI marker is not greater than approximately 90% of the distance between the first passive MRI marker and the third passive MRI marker when the flexible distal region is in the straight state; and, optionally, wherein when the flexible distal region is in the preset curved shape, the distance between the first passive MRI marker and the third passive MRI marker does not exceed approximately 50% of the distance between the first and third passive MRI markers when the flexible distal region is in the straight state.

[0220] Example 73. An interventional medical device according to any of Examples 61 to 72, wherein the second passive MRI marker is located on the distal region to mark the distal position of the preset curve shape.

[0221] Example 74. An interventional medical device according to any one of Examples 61 to 73, wherein the guidewire is optionally said guidewire comprising a core member and a polymer sheath encapsulating the core member.

[0222] Example 75. The interventional medical device according to Example 74, wherein the guidewire includes a core member and a polymer sheath encapsulating the core member, and wherein the core member is a single continuous length of metal wire.

[0223] Example 76. The interventional medical device according to Example 75, wherein the metal wire is formed of a superelastic metal alloy.

[0224] Example 77. The interventional medical device according to Example 76, wherein the superelastic metal alloy is nickelitanol.

[0225] Example 78. An interventional medical device according to any one of Examples 74 to 77, wherein the polymer sheath is formed of a polyamide polymer.

[0226] Example 79. An interventional medical device according to any one of Examples 73 to 78, wherein the first passive MRI marker and the second passive MRI marker each comprise a passive MRI marker forming material between the polymer sheath and the core member.

[0227] Example 80. The interventional medical device according to Example 79, wherein the passive MRI marker forming material is a metal layer plated on the outer surface of the core member, optionally wherein the metal layer is a nickel layer.

[0228] Example 81. An interventional medical device according to any one of Examples 74 to 78, wherein the first passive MRI marker and the second passive MRI marker each comprise a passive MRI marker forming material embedded in the wall of the polymer sheath.

[0229] Example 82. The interventional medical device according to any one of Examples 61 to 72 is a catheter.

[0230] Example 83. The interventional medical device according to Example 82, wherein the catheter has at least one side port.

[0231] Example 84. The interventional medical device according to Example 83, wherein the at least one side port is located distal to the first passive MRI marker, and the elongated member does not contain any side ports located proximal to the first passive MRI marker.

[0232] Example 85. An interventional medical device according to any one of Examples 82 to 84, wherein the first passive MRI marker and the second passive MRI marker each comprise a passive MRI marker forming material embedded in the wall of the catheter.

[0233] Example 86. An interventional medical device according to Example 85, wherein the wall of the catheter comprises a first volume of polymer material forming the wall located radially inside the passive MRI marker forming material and between the passive MRI marker forming material and the catheter lumen surface defined by the first volume of polymer material.

[0234] Example 87. An interventional medical device according to any one of Examples 82 to 86, wherein the flexible distal region is formed of a thermoplastic elastomer material.

[0235] Example 88. An interventional medical device according to any one of Examples 61 to 87, wherein the preset curve shape is rotated by at least about 90 degrees, at least about 180 degrees, or at least about 360 degrees.

[0236] Example 89. The interventional medical device according to Example 88, wherein the preset curve shape is rotated by no more than about 720 degrees.

[0237] Example 90. An interventional medical device according to any of Examples 61 to 89, wherein the second passive MRI marker appears at a position where the preset curve shape has been rotated between approximately 65 degrees and approximately 115 degrees.

[0238] Example 91. An interventional medical device according to any one of Examples 61 to 90, wherein the first passive MRI marker and the second passive MRI are each located within a longitudinal length of the elongated member of not more than about 10 mm, or not more than about 5 mm, or in the range of about 0.2 to about 5 mm.

[0239] Example 92. An interventional medical device according to any one of Examples 61 to 91, wherein the first passive MRI marker and the second passive MRI marker appear within a width across the elongated member such that the width does not exceed approximately 70% of the outer width of the elongated member at the respective positions of the first passive MRI marker and the second passive MRI marker.

[0240] Example 93. An interventional medical device according to any one of Examples 61 to 92, wherein the first passive MRI marker and the second passive MRI marker each include (i) an MRI marker forming material, the volume of which does not exceed 5 mm. 3 or not exceeding 3 mm 3 or not exceeding 1 mm 3 or not exceeding 0.1 mm 3 In each of these aspects, the volume can be at least 0.00005 mm. 3 or at least about 0.0001 mm 3 ; or (i) an MRI marker forming material having a magnetic susceptibility of at least about 1 and a volume not exceeding 0.1 mm. 3 or in 0.00001 mm 3 Up to 0.1 mm 3 Within the range, or 0.00005 mm 3 Up to 0.02 mm 3 Within the range.

[0241] Example 94. An interventional medical device according to any one of Examples 61 to 93, wherein the first passive MRI marker and the second passive MRI marker each comprise an MRI marker forming material, the MRI marker forming material having a magnetic susceptibility of at least about 500 ppm, or at least about 2000 ppm, or in the range of about 500 ppm to about 1000, or in the range of about 7000 ppm to about 1000.

[0242] Example 95. An interventional medical device according to any one of Examples 61 to 94, wherein the first passive MRI marker and the second passive MRI marker each include an MRI marker forming material selected from nickel, nickel alloys, cobalt, cobalt alloys, iron, and iron alloys.

[0243] Example 96. An interventional medical device according to any one of Examples 61 to 95, wherein:

[0244] The first passive MRI marker and the second passive MRI marker are configured to produce artifacts of different sizes; or

[0245] The first passive MRI marker and the second passive MRI marker are formed from the same passive MRI marker forming material, but the passive MRI marker forming material has different volumes; or

[0246] The first passive MRI marker is formed from a first passive MRI marker forming material, and the second passive MRI marker is formed from a second passive MRI marker forming material, wherein the magnetic susceptibility of the first passive MRI marker forming material is different from the magnetic susceptibility of the second passive MRI marker forming material.

[0247] Example 97. An interventional medical device according to any of Examples 61 to 96, wherein the first passive MRI marker and the second passive MRI marker each include a passive MRI marker forming material layer, optionally wherein the layer is in the form of a circumferential band.

[0248] Example 98. An interventional medical device according to any one of Examples 61 to 96, wherein the first passive MRI marker and the second passive marker each include a plug of passive MRI marker forming material, optionally wherein the plug does not overlap with the innermost portion of the elongated member, wherein the innermost portion extends along a line extending along a first curve of the preset curve shape when the distal region is in the preset curve shape, and the plug does not overlap with the outermost portion of the elongated member, wherein the outermost portion extends along a line extending along a second curve when the distal region is in the preset curve shape, the second curve being opposite to the first curve.

[0249] Example 99. A method for manufacturing an interventional medical device useful in a process guided by magnetic resonance imaging (MRI), comprising:

[0250] An elongated member is provided, the elongated member being configured for insertion into a patient and having a flexible distal region having a predetermined curved shape in a relaxed state, but being elastically configured into a second shape by applying force, the second shape being different from the predetermined curved shape;

[0251] Provide a first passive MRI marker at a first location along the elongated member, the first passive MRI marker being configured to produce a first artifact under MRI; and

[0252] A second passive MRI marker is provided at a second location distal to the first location and along the flexible distal region, the second passive MRI marker being configured to produce a second artifact under the MRI.

[0253] Example 100. The method according to Example 99, wherein:

[0254] The provision of the elongated member includes processing the elongated member to introduce the predetermined curved shape; and

[0255] The provision of a second passive MRI marker is performed prior to the treatment.

[0256] Example 101. The method according to Example 100, wherein:

[0257] The provision of passive markers includes embedding a certain volume of passive MRI marker forming material into a polymer material of the elongated member; and

[0258] The process includes heating the polymer material to reset its shape in the presence of the given volume of passive MRI marker-forming material.

[0259] Example 102. The method according to any one of Examples 99 to 101, wherein the interventional medical device is a catheter and the elongated member is a catheter shaft.

[0260] Example 103. The method according to any of Examples 99 to 102, wherein the first passive MRI marker is also along the flexible distal region.

[0261] Example 104. The method according to any one of Examples 99 to 103, wherein:

[0262] The interventional medical device is a catheter as described in any one of embodiments 1 to 18, 28 to 40, 61 to 72 or 82 to 98.

[0263] While embodiments of the present disclosure have been detailed and described in the accompanying drawings and foregoing description, their features are to be considered illustrative rather than restrictive. It should be understood that only some embodiments have been shown and described, and it is intended to protect all changes and modifications within the spirit of the present disclosure herein. By way of example, it should be understood that a single feature or combination of features (e.g., 2, 3, or 4 features) described in the detailed description above may be combined with the features of the following claims to provide additional embodiments herein.

[0264] Unless otherwise specified herein or the context clearly contradicts it, the use of the terms “an,” “a,” and “the,” as well as similar indicators (especially in the context of the appended claims), should be interpreted as encompassing both singular and plural forms. Unless otherwise specified herein, the descriptions of ranges of values ​​herein are intended only as a concise way of individually referring to each individual value falling within that range, and each individual value is incorporated into the specification as if individually stated herein. Unless otherwise specified herein or the context clearly contradicts it, all methods described herein may be performed in any suitable order. Unless otherwise claimed, the use of any and all examples or exemplary language (e.g., “such as”) provided herein is intended only to better illustrate embodiments of this disclosure and does not constitute a limitation on the scope of this disclosure. No language in the specification should be construed as indicating that any unclaimed element is necessary for the practice of the products and methods defined in these claims.

[0265] All references cited in this article demonstrate the level of expertise in this field and are incorporated herein by reference in their entirety.

Claims

1. An interventional medical device useful in magnetic resonance imaging (MRI) guided procedures, comprising: An elongated member configured for insertion into a patient and having a flexible distal region having a predetermined curved shape in a relaxed state, but which can be elastically configured into a second shape by applying force, the second shape being different from the predetermined curved shape. A first passive MRI marker, located at a first position along the elongated member, is configured to produce a first artifact under the MRI. A second passive MRI marker is located at a second location distal to the first location and along the flexible distal region, the second passive MRI marker being configured to produce a second artifact under the MRI. When the flexible distal region moves from the second shape to the preset curved shape, the change in the relative position of the first passive MRI marker with respect to the second passive MRI marker is visually detectable under MRI.

2. The interventional medical device according to claim 1, wherein in the preset curved shape, the flexible distal region has a longitudinal axis extending in a plane.

3. The interventional medical device according to claim 1 or 2, wherein the first artifact has a first maximum size, the first maximum size being about 1.5 to about 50 times the first outer diameter of the first longitudinal segment of the catheter shaft on which the first passive MRI marker is present, and the second artifact has a second maximum size, the second maximum size being about 1.5 to about 50 times the second outer diameter of the second longitudinal segment of the catheter shaft on which the second passive MRI marker is present; and optionally, wherein the first artifact has a maximum size, the maximum size being about 2 to about 20 times the first outer diameter, and the second artifact has a second maximum size, the second maximum size being about 2 to about 20 times the second outer diameter.

4. The interventional medical device according to any one of claims 1 to 3, wherein the first artifact and the second artifact have a minimum size, said minimum size being at least about 2 times, or at least about 3 times, larger than the maximum diameter of the flexible distal region of the elongated body.

5. The interventional medical device according to any one of claims 1 to 4, wherein when the flexible distal region moves between the second shape and the preset curved shape, the second passive MRI marker moves laterally relative to the first passive MRI marker.

6. The interventional medical device according to any one of claims 1 to 5, wherein when the flexible distal region moves between the second shape and the preset curved shape, the second passive MRI marker moves closer to the first passive MRI marker, optionally wherein the second shape is a straight state of the flexible distal region, and when the distal region is in the preset curved shape, the distance between the first passive MRI marker and the second passive MRI marker does not exceed approximately 90% of the distance between the first passive MRI marker and the second passive MRI marker when the distal region is in the straight state, and preferably does not exceed approximately 50% of the distance between the first passive MRI marker and the second passive MRI marker when the distal region is in the straight state.

7. The interventional medical device according to any one of claims 1 to 6, further comprising a third passive MRI marker, wherein the third passive MRI marker is longitudinally positioned proximal to the second passive MRI marker along the distal region.

8. The interventional medical device of claim 7, wherein when the flexible distal region is in the second shape, the second passive MRI marker is distal to the third passive MRI marker, and wherein when the flexible distal region is in the preset curved shape, the second passive MRI marker is proximal to the third passive MRI marker.

9. The interventional medical device according to any one of claims 1 to 8, wherein the first passive MRI marker is located on the elongated member at a position proximal to the flexible distal region.

10. The interventional medical device of claim 9, wherein the first passive MRI marker is located within approximately 2 cm proximally in the distal region.

11. The interventional medical device according to any one of claims 1 to 8, wherein the first passive MRI marker is located on the flexible distal region at a position proximal to the second passive MRI marker.

12. The interventional medical device of claim 11, wherein when the flexible distal region is in the second shape, the second passive MRI marker is distal to the first passive MRI marker, and wherein when the flexible distal region is in the preset curved shape, the second passive MRI marker is proximal to the first passive MRI marker.

13. The interventional medical device according to any one of claims 1 to 12, wherein the device is a catheter.

14. The interventional medical device of claim 13, wherein the catheter has at least one side port.

15. The interventional medical device of claim 14, wherein the at least one side port is located distal to the first passive MRI marker, and the elongated member does not contain any side port located proximal to the first passive MRI marker.

16. The interventional medical device according to any one of claims 13 to 15, wherein the first passive MRI marker and the second passive MRI marker each comprise a passive MRI marker forming material embedded in the wall of the catheter.

17. The interventional medical device of claim 16, wherein the wall of the catheter comprises a first volume of polymer material forming the wall located radially inside the passive MRI marker forming material and between the passive MRI marker forming material and the catheter lumen surface defined by the first volume of polymer material.

18. The interventional medical device according to any one of claims 13 to 17, wherein the flexible distal region is formed of a thermoplastic elastomer material.

19. The interventional medical device according to any one of claims 1 to 12, wherein the device is a guidewire.

20. The interventional medical device of claim 19, wherein the guidewire comprises a core member and a polymer sheath encapsulating the core member.

21. The interventional medical device of claim 20, wherein the core component is a single continuous metal wire.

22. The interventional medical device of claim 21, wherein the wire is formed of a superelastic metal alloy.

23. The interventional medical device of claim 22, wherein the superelastic metal alloy is nickel-titanium alloy.

24. The interventional medical device according to any one of claims 20 to 23, wherein the polymer sheath is formed of a polyamide polymer.

25. The interventional medical device according to any one of claims 20 to 24, wherein the first passive MRI marker and the second passive MRI marker each comprise a passive MRI marker forming material between the polymer sheath and the core member.

26. The interventional medical device of claim 25, wherein the passive MRI marker forming material is a metal layer plated on the outer surface of the core member, optionally wherein the metal layer is a nickel layer.

27. The interventional medical device according to any one of claims 20 to 24, wherein the first passive MRI marker and the second passive MRI marker each comprise a passive MRI marker forming material embedded in the wall of the polymer sheath.

28. The interventional medical device according to any one of claims 1 to 27, wherein the preset curve shape is rotated by at least about 90 degrees, at least about 180 degrees, or at least about 360 degrees.

29. The interventional medical device of claim 28, wherein the preset curve shape rotates by no more than about 720 degrees.

30. The interventional medical device of claim 28 or 29, wherein the second passive MRI marker appears at a position where the preset curve shape has been rotated between approximately 65 degrees and approximately 115 degrees.

31. The interventional medical device according to any one of claims 1 to 30, wherein the first passive MRI marker and the second passive MRI marker are each located within a longitudinal length of the elongated member of not more than about 10 mm, or not more than about 5 mm, or in the range of about 0.2 to about 5 mm.

32. The interventional medical device of claim 31, wherein the first passive MRI marker and the second passive MRI marker each comprise a passive MRI marker forming material layer, optionally wherein the layer is in the form of a circumferential band.

33. The interventional medical device of claim 32, wherein the first passive MRI marker and the second passive marker each comprise a plug of passive MRI marker forming material, optionally wherein the plug does not overlap with the innermost portion of the elongated member, wherein the innermost portion extends along a first curve of the preset curve shape when the distal region is in the preset curve shape, and the plug also does not overlap with the outermost portion of the elongated member, wherein the outermost portion extends along a second curve opposite to the first curve when the distal region is in the preset curve shape.

34. The interventional medical device according to any one of claims 1 to 32, wherein the first passive MRI marker and the second passive MRI marker appear within a width across the elongated member such that the width does not exceed approximately 70% of the outer width of the elongated member at the respective locations of the first passive MRI marker and the second passive MRI marker.

35. The interventional medical device according to any one of claims 1 to 34, wherein the first passive MRI marker and the second passive MRI marker each comprise (i) an MRI marker forming material, the volume of the MRI marker forming material not exceeding 5 mm. 3 or not exceeding 3 mm 3 or not exceeding 1 mm 3 or not exceeding 0.1 mm 3 In each of these aspects, the volume can be at least 0.00005 mm. 3 or at least about 0.0001 mm 3 ; or (i) an MRI marker forming material having a magnetic susceptibility of at least about 1 and a volume not exceeding 0.1 mm. 3 or in 0.00001 mm 3 up to 0.1 mm 3 Within the range, or 0.00005 mm 3 Up to 0.02 mm 3 Within the range.

36. The interventional medical device according to any one of claims 1 to 35, wherein the first passive MRI marker and the second passive MRI marker each comprise an MRI marker forming material, the MRI marker forming material having a magnetic susceptibility of at least about 500 ppm, or at least about 2000 ppm, or in the range of about 500 ppm to about 1000, or in the range of about 7000 ppm to about 1000.

37. The interventional medical device according to any one of claims 1 to 36, wherein the first passive MRI marker and the second passive MRI marker each comprise an MRI marker forming material selected from nickel, nickel alloys, cobalt, cobalt alloys, iron, and iron alloys.

38. The interventional medical device according to any one of claims 1 to 37, further comprising a proximal reference passive MRI marker located on the elongated member proximal to the first passive MRI marker, optionally wherein the proximal reference passive MRI marker is configured to produce artifacts (i) having a maximum size greater than the maximum size of the first passive MRI marker and the maximum size of the second passive MRI marker, or (ii) having a maximum size greater than the maximum size of any discrete MRI marker distal to the proximal reference passive MRI marker.

39. The interventional medical device according to claim 38, wherein: The first passive MRI marker is longitudinally adjacent to the second passive MRI marker and located at a first longitudinal distance from the second passive marker, wherein the proximal reference passive MRI marker is located at a second longitudinal distance from the first passive MRI marker, and wherein the second longitudinal distance is at least twice the first longitudinal distance; and / or The proximal reference passive MRI marker is configured to produce artifacts, the maximum size of which is at least about 1.25 times the maximum size of the first passive MRI marker and the maximum size of the second passive MRI marker.

40. The interventional medical device according to any one of claims 1 to 39, wherein: The first passive MRI marker and the second passive MRI marker are configured to produce artifacts of different sizes; or The first passive MRI marker and the second passive MRI marker are formed from the same passive MRI marker forming material, but the passive MRI marker forming material has different volumes; or The first passive MRI marker is formed from a first passive MRI marker forming material, and the second passive MRI marker is formed from a second passive MRI marker forming material, wherein the magnetic susceptibility of the first passive MRI marker forming material is different from the magnetic susceptibility of the second passive MRI marker forming material.

41. An interventional system useful in medical procedures guided by magnetic resonance imaging (MRI) under a main magnetic field strength, comprising: A first elongated medical device for treating a target area of ​​a patient using a distal region of the first elongated medical device, the first elongated medical device having a distal end, the first elongated medical device including a first passive MRI marker. as well as A second elongated medical device is positioned through the lumen of the first elongated medical device to position a distal region of the second elongated medical device distal to the distal end of the first elongated medical device, the distal region of the second elongated medical device including a first passive MRI marker. The first passive MRI marker of the first elongated medical device is configured to produce a first medical device localization artifact with the largest size under the MRI. The first passive MRI marker of the second elongated medical device is configured to produce a second medical device localization artifact of maximum size under the MRI; and The maximum size of the second medical device positioning artifact is greater than the maximum size of the first medical device positioning artifact.

42. The interventional system of claim 41, wherein the first elongated medical device is a catheter.

43. The interventional system according to claim 41 or 42, wherein the second elongated medical device is a guidewire.

44. The interventional system of claim 43, wherein the guidewire comprises a core member and a polymer sheath encapsulating the core member.

45. The intervention system of claim 44, wherein the core component is a single continuous metal wire.

46. ​​The intervention system of claim 45, wherein the metal wire is formed of a superelastic metal alloy.

47. The intervention system of claim 46, wherein the superelastic metal alloy is nickelitanol.

48. The intervention system according to any one of claims 44 to 47, wherein the polymer sheath is formed of a polyamide polymer.

49. The interventional system according to any one of claims 44 to 48, wherein the first passive MRI marker and the second passive MRI marker each comprise a passive MRI marker forming material between the polymer sheath and the core member.

50. The interventional system of claim 49, wherein the passive MRI marker forming material is a metal layer plated on the outer surface of the core member, optionally wherein the metal layer is a nickel layer.

51. The interventional system according to any one of claims 44 to 48, wherein the first passive MRI marker and the second passive MRI marker each comprise a passive MRI marker forming material embedded in the wall of the polymer sheath.

52. The interventional system according to any one of claims 41 to 51, wherein the distal region of the second elongated medical device has a longitudinal length of at least about 5 cm, or at least about 7 cm, or at least about 10 cm, or in the range of about 5 to about 30 cm, or in the range of about 7 cm to 20 cm.

53. The interventional system according to any one of claims 41 to 52, wherein the first passive MRI marker of the second elongated medical device is a proximal discrete MRI marker in the distal region of the second elongated medical device, and wherein the system is locatable to a first configuration in which the first passive MRI marker of the second elongated medical device is longitudinally spaced a first distance distal to the distal end of the first elongated medical device, wherein the first distance is at least about 7 cm, or at least about 10 cm, or in the range of 7 to 30 cm.

54. The interventional system of claim 53, wherein the first passive MRI marker of the first elongated medical device is the most distal discrete MRI marker of the first elongated medical device, and wherein, in the first configuration, the first passive MRI marker of the second medical device is longitudinally spaced by a second distance distal to the first passive MRI marker of the first elongated medical device, wherein the second distance does not exceed approximately 1.25 times the first distance.

55. The interventional system according to any one of claims 41 to 54, wherein the first medical device is a catheter, and wherein the first passive MRI marker comprises a passive MRI marker forming material embedded in the wall of the catheter.

56. The interventional system of claim 55, wherein the wall of the catheter comprises a first volume of polymer material forming the wall located radially inside the passive MRI marker forming material and between the passive MRI marker forming material and the catheter lumen surface defined by the first volume of polymer material.

57. The intervention system of claim 56, wherein the polymer material comprises a thermoplastic elastomer material.

58. The interventional system according to any one of claims 41 to 57, wherein the first passive MRI marker and the second passive MRI marker each comprise (i) an MRI marker forming material, the volume of the MRI marker forming material not exceeding 5 mm. 3 or not exceeding 3 mm 3 or not exceeding 1 mm 3 or not exceeding 0.1 mm 3 In each of these aspects, the volume can be at least 0.00005 mm. 3 or at least about 0.0001 mm 3 ; or (i) an MRI marker forming material having a magnetic susceptibility of at least about 1 and a volume not exceeding 0.1 mm. 3 or in 0.00001 mm 3 up to 0.1 mm 3 Within the range, or 0.00005 mm 3 Up to 0.02 mm 3 Within the range.

59. The interventional system according to any one of claims 41 to 58, wherein the first passive MRI marker and the second passive MRI marker each comprise an MRI marker forming material, the MRI marker forming material having a magnetic susceptibility of at least about 500 ppm, or at least about 2000 ppm, or in the range of about 500 ppm to about 1000, or in the range of about 7000 ppm to about 1000.

60. The intervention system according to any one of claims 41 to 59, wherein: The first passive MRI marker and the second passive MRI marker each include an MRI marker forming material, wherein the MRI marker forming material is selected from nickel, nickel alloys, cobalt, cobalt alloys, iron, and iron alloys; or The first passive MRI marker and the second passive MRI marker are configured to produce visible artifacts of different sizes; or The first passive MRI marker and the second passive MRI marker are formed from the same passive MRI marker forming material, but the passive MRI marker forming material has different volumes; or The first passive MRI marker is formed from a first passive MRI marker forming material, and the second passive MRI marker is formed from a second passive MRI marker forming material, wherein the magnetic susceptibility of the first passive MRI marker forming material is different from the magnetic susceptibility of the second passive MRI marker forming material.

61. An interventional medical device useful under magnetic resonance imaging (MRI), comprising: An elongated member configured for insertion into a patient and having a flexible distal region having a predetermined curved shape in a relaxed state, but elastically configurable into a straight state when force is applied. A first passive MRI marker is located at a first position along the elongated member; A second passive MRI marker is located at a second position along the elongated member, the second position being longitudinally spaced from the first position; as well as in: (i) The first passive MRI marker is proximal to the flexible distal region having the preset curved shape, and the second passive MRI marker is longitudinally located distal to the first passive MRI marker and on the flexible distal region having the preset curved shape, wherein when the distal region is in the preset curved shape, the second passive MRI marker is closer to the first passive marker than when the distal region is in the straight state; or (ii) Both the first passive MRI marker and the second passive MRI marker are located on the flexible distal region having the preset curved shape, and are configured to produce corresponding discrete visible artifacts under MRI at a main magnetic field strength of at least one of 0.55T, 1.5T, and 3T when the flexible distal region is in the straight state and the preset curved shape; or (iii) One of the first passive MRI marker or the second passive MRI marker is positioned on the distal region to mark the distal position of the preset curve shape.

62. The interventional medical device of claim 61, wherein the first passive MRI marker is located proximally to the flexible distal region having a preset curved shape, and the second passive MRI marker is located on the flexible distal region having a preset curved shape, wherein when the distal region is in the preset curved shape, the second passive MRI marker is closer to the first passive marker than when the distal region is in the straight state.

63. The interventional medical device of claim 62, wherein when the distal region is in the preset curved shape, the distance between the first passive MRI marker and the second passive MRI marker does not exceed about 90% of the distance between the first passive MRI marker and the second passive MRI marker when the distal region is in the straight state, and optionally, wherein the first passive MRI marker is longitudinally positioned within 2 cm of the flexible distal region.

64. The interventional medical device according to any one of claims 61 to 63, further comprising a third passive MRI marker; and optionally, wherein at least one of the first, second, and third passive MRI markers is configured to produce a visible artifact, the size of which differs from at least one other passive MRI marker among the first, second, and third passive MRI markers.

65. The interventional medical device of claim 64, wherein the third passive MRI marker is located on the distal region and is longitudinally positioned between the first passive MRI marker and the second passive MRI marker along the elongated member.

66. The interventional medical device of claim 65, wherein when the flexible distal region is in the straight state, the second passive MRI marker is distal to the third passive MRI marker, and wherein when the flexible distal region is in the preset curved shape, the second passive MRI marker is proximal to the third passive MRI marker.

67. The interventional medical device of claim 65 or 66, wherein when the distal region is in the preset curved shape, the second passive MRI marker is closer to the first passive marker than when the distal region is in the straight state.

68. The interventional medical device of claim 62, wherein the first passive MRI marker and the second passive MRI marker are both on the flexible distal region having the preset curved shape and are longitudinally spaced apart from each other, and are configured to produce corresponding discrete visible artifacts under MRI at a main magnetic field strength of at least one of 0.55T, 1.5T, and 3T when the flexible distal region is in the straight state and the preset curved shape.

69. The interventional medical device of claim 68, wherein the second passive MRI marker is located longitudinally proximal to the first passive MRI marker in the flexible distal region, and wherein when the flexible distal region is in the straight state, the first passive MRI marker is located distal to the second passive MRI marker, and when the flexible distal region is in the preset curved shape, the first passive MRI marker is located proximal to the second passive MRI marker.

70. The interventional medical device of claim 68 or 69, further comprising a third passive MRI marker; and optionally, wherein at least one of the first, second, and third passive MRI markers is configured to produce a visible artifact, the size of which differs from at least one other passive MRI marker among the first, second, and third passive MRI markers.

71. The interventional medical device of claim 70, wherein the third passive MRI marker is longitudinally positioned within approximately 2 cm proximal to the flexible distal region.

72. The interventional medical device according to any one of claims 69 to 71, wherein when the flexible distal region is in the preset curved shape, the distance between the first passive MRI marker and the third passive MRI marker is not greater than approximately 90% of the distance between the first passive MRI marker and the third passive MRI marker when the flexible distal region is in the straight state; and optionally, wherein when the flexible distal region is in the preset curved shape, the distance between the first passive MRI marker and the third passive MRI marker does not exceed approximately 50% of the distance between the first and third passive MRI markers when the flexible distal region is in the straight state.

73. The interventional medical device according to any one of claims 61 to 72, wherein the second passive MRI marker is located on the distal region to mark the distal position of the preset curve shape.

74. The interventional medical device according to any one of claims 61 to 73, wherein the guidewire is optionally comprising a core member and a polymer sheath encapsulating the core member.

75. The interventional medical device of claim 74, wherein the guidewire comprises a core member and a polymer sheath encapsulating the core member, and wherein the core member is a single continuous length of metal wire.

76. The interventional medical device of claim 75, wherein the wire is formed of a superelastic metal alloy.

77. The interventional medical device of claim 76, wherein the superelastic metal alloy is nickel-titanium alloy.

78. The interventional medical device according to any one of claims 74 to 77, wherein the polymer sheath is formed of a polyamide polymer.

79. The interventional medical device according to any one of claims 73 to 78, wherein the first passive MRI marker and the second passive MRI marker each comprise a passive MRI marker forming material between the polymer sheath and the core member.

80. The interventional medical device of claim 79, wherein the passive MRI marker forming material is a metal layer plated on the outer surface of the core member, optionally wherein the metal layer is a nickel layer.

81. The interventional medical device according to any one of claims 74 to 78, wherein the first passive MRI marker and the second passive MRI marker each comprise a passive MRI marker forming material embedded in the wall of the polymer sheath.

82. The interventional medical device according to any one of claims 61 to 72, wherein it is a catheter.

83. The interventional medical device of claim 82, wherein the catheter has at least one side port.

84. The interventional medical device of claim 83, wherein the at least one side port is located distal to the first passive MRI marker, and the elongated member does not contain any side port located proximal to the first passive MRI marker.

85. The interventional medical device according to any one of claims 82 to 84, wherein the first passive MRI marker and the second passive MRI marker each comprise a passive MRI marker forming material embedded in the wall of the catheter.

86. The interventional medical device of claim 85, wherein the wall of the catheter comprises a first volume of polymer material forming the wall located radially inside the passive MRI marker forming material and between the passive MRI marker forming material and the catheter lumen surface defined by the first volume of polymer material.

87. The interventional medical device according to any one of claims 82 to 86, wherein the flexible distal region is formed of a thermoplastic elastomer material.

88. The interventional medical device according to any one of claims 61 to 87, wherein the preset curve shape is rotated by at least about 90 degrees, at least about 180 degrees, or at least about 360 degrees.

89. The interventional medical device according to claim 88, wherein the preset curve shape rotates by no more than about 720 degrees.

90. The interventional medical device according to any one of claims 61 to 89, wherein the second passive MRI marker appears at a position where the preset curve shape has been rotated between approximately 65 degrees and approximately 115 degrees.

91. The interventional medical device according to any one of claims 61 to 90, wherein the first passive MRI marker and the second passive MRI marker are each located within a longitudinal length of the elongated member of no more than about 10 mm, or no more than about 5 mm, or in the range of about 0.2 to about 5 mm.

92. The interventional medical device according to any one of claims 61 to 91, wherein the first passive MRI marker and the second passive MRI marker appear within a width across the elongated member such that the width does not exceed approximately 70% of the outer width of the elongated member at the respective locations of the first passive MRI marker and the second passive MRI marker.

93. The interventional medical device according to any one of claims 61 to 92, wherein the first passive MRI marker and the second passive MRI marker each comprise (i) an MRI marker forming material, the volume of the MRI marker forming material not exceeding 5 mm. 3 or not exceeding 3 mm 3 or not exceeding 1 mm 3 or not exceeding 0.1 mm 3 In each of these aspects, the volume can be at least 0.00005 mm. 3 or at least about 0.0001 mm 3 ; or (i) an MRI marker forming material having a magnetic susceptibility of at least about 1 and a volume not exceeding 0.1 mm. 3 or in 0.00001 mm 3 up to 0.1 mm 3 Within the range, or 0.00005 mm 3 Up to 0.02 mm 3 Within the range.

94. The interventional medical device according to any one of claims 61 to 93, wherein the first passive MRI marker and the second passive MRI marker each comprise an MRI marker forming material, the MRI marker forming material having a magnetic susceptibility of at least about 500 ppm, or at least about 2000 ppm, or in the range of about 500 ppm to about 1000, or in the range of about 7000 ppm to about 1000.

95. The interventional medical device according to any one of claims 61 to 94, wherein the first passive MRI marker and the second passive MRI marker each comprise an MRI marker forming material selected from nickel, nickel alloys, cobalt, cobalt alloys, iron, and iron alloys.

96. The interventional medical device according to any one of claims 61 to 95, wherein: The first passive MRI marker and the second passive MRI marker are configured to produce artifacts of different sizes; or The first passive MRI marker and the second passive MRI marker are formed from the same passive MRI marker forming material, but the passive MRI marker forming material has different volumes; or The first passive MRI marker is formed from a first passive MRI marker forming material, and the second passive MRI marker is formed from a second passive MRI marker forming material, wherein the magnetic susceptibility of the first passive MRI marker forming material is different from the magnetic susceptibility of the second passive MRI marker forming material.

97. The interventional medical device according to any one of claims 61 to 96, wherein the first passive MRI marker and the second passive MRI marker each comprise a passive MRI marker forming material layer, optionally wherein the layer is in the form of a circumferential band.

98. The interventional medical device according to any one of claims 61 to 96, wherein the first passive MRI marker and the second passive marker each comprise a plug of passive MRI marker forming material, optionally wherein the plug does not overlap with the innermost portion of the elongated member, wherein the innermost portion extends along a first curve of the preset curve shape when the distal region is in the preset curve shape, and the plug also does not overlap with the outermost portion of the elongated member, wherein the outermost portion extends along a second curve opposite to the first curve when the distal region is in the preset curve shape.

99. A method for manufacturing an interventional medical device useful in a process guided by magnetic resonance imaging (MRI), comprising: An elongated member is provided, the elongated member being configured for insertion into a patient and having a flexible distal region having a predetermined curved shape in a relaxed state, but being elastically configured into a second shape by applying force, the second shape being different from the predetermined curved shape; A first passive MRI marker is provided at a first location along the elongated member, the first passive MRI marker being configured to produce a first artifact under the MRI. as well as A second passive MRI marker is provided at a second location distal to the first location and along the flexible distal region, the second passive MRI marker being configured to produce a second artifact under the MRI.

100. The method according to claim 99, wherein: The provision of the elongated member includes processing the elongated member to introduce the predetermined curved shape; and The provision of a second passive MRI marker is performed prior to the treatment.

101. The method of claim 100, wherein: The provision of passive markers includes embedding a certain volume of passive MRI marker forming material into a polymer material of the elongated member; and The process includes heating the polymer material to reset its shape in the presence of the given volume of passive MRI marker-forming material.

102. The method according to any one of claims 99 to 101, wherein the interventional medical device is a catheter, and the elongated member is a catheter shaft.

103. The method according to any one of claims 99 to 102, wherein the first passive MRI marker is also along the flexible distal region.

104. The method according to any one of claims 99 to 103, wherein The interventional medical device is a catheter as described in any one of claims 1 to 18, 28 to 40, 61 to 72, or 82 to 98.

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