Method and apparatus for preventing transponder tag migration within tissue

Abstract

A marking system for implantation into tissue includes a marker body having an outer surface, the marker body including a transponder configured to respond to electromagnetic radiation from an external source and a microchip operatively connected to the transponder and configured to activate in response to the electromagnetic radiation, and an anti-migration device configured to receive at least a portion of the marker body, engage tissue into which the marker body is to be implanted, and resist migration of the marker body after implantation. Deployment devices, systems, and methods for implanting the marking system include use of a device having a handle portion and a cannula through which the marking system is disposed.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority to U.S. Provisional Application No. 63 / 380,825, filed October 25, 2022, the entire contents of which are incorporated herein by reference.

[0002] (Technical field) The present invention relates generally to location determination devices, and more particularly to methods and apparatus used to prevent migration of implantable location determination devices, such as transponder tags, within tissue. [Background technology]

[0003] (Introduction) Prior to a biopsy or surgical procedure to remove a lesion within the breast, such as a lumpectomy procedure, the location of the lesion must be identified. For example, mammography or ultrasound imaging may be used to identify and / or confirm the location of the lesion prior to the procedure. The resulting image may be used by the surgeon to identify the location of the lesion and guide the surgeon during the procedure, e.g., during incision to access and / or remove the lesion. To facilitate localization, just prior to the procedure, a wire may be inserted into the breast, e.g., via a needle, such that the tip of the wire is positioned at the location of the lesion. Once the wire is positioned, it may be secured in place where it exits the breast, e.g., using a bandage or tape applied to the patient's skin. Once the wire is in place and secured, the patient may proceed with surgery, e.g., to perform a biopsy or lumpectomy.

[0004] As an alternative to wires, radio frequency identification (RFID) tags, such as passive integrated transponder (PIT) tags, can be used to mark the location of target tumors, lesions, body structures, or areas within a patient's tissue, with the intention that the tag can be used to help a surgeon or clinician later locate the structure, abnormality, or area for treatment. PIT tags provide increased accuracy and / or enable differentiation between multiple implanted devices. Each PIT tag generally includes a small ferrite-core coil attached to a microchip enclosed within a glass cover or envelope. The microchip has a capacitor that, when energized, causes the coil to resonate at a predetermined frequency, and circuitry that generates and transmits a coded identification number or message in response to a received interrogation signal that energizes the coil. Such PIT tags generally do not include an internal energy source. Instead, the energy needed to transmit the coded identification number is obtained through electromagnetic coupling, which causes the transfer of energy from the powered device to the PIT tag.

[0005] PIT tags can be injected up to several centimeters (cm) below the outer surface of a patient's skin using a needle, cannula, or other suitable deployment method to place the tag at or near a target, with the intention that the tag can be used to later help a surgeon or clinician locate the target for treatment. For example, such tags can be used to mark a lesion or tumor in breast tissue for surgical removal. Neoadjuvant therapy, such as chemotherapy, radiation therapy, and hormone therapy, can be provided prior to surgical removal to reduce the size of the lesion or tumor. In such cases, the PIT tag can be used to mark the area for treatment and will remain in the tissue until later surgery to remove the lesion or tumor. In many applications, implanted PIT tags are intended to remain in place for an extended period of time, such as between two procedures or for the patient's lifetime. In some situations, it is beneficial to be able to quickly and accurately determine the location of the PIT tag in terms of its depth relative to the patient's skin. For example, knowing the exact location of a PIT tag is useful for minimizing the size of the incision required to remove the PIT tag from a patient.

[0006] However, the use of implanted PIT tags can present certain challenges to practitioners. When PIT tags are stored within a deployment system (e.g., a cannula) prior to implantation, practitioners must ensure that the PIT tag does not migrate out of the deployment system during transportation or storage. Challenges remain even after implantation. For example, implanted PIT tags may migrate over time within the path of the needle or cannula used to insert the implanted PIT tag, or in other directions. Such migration may occur immediately after deployment, after treatment such as neoadjuvant therapy, or over time after other procedures. Furthermore, in some cases, failures may occur during the deployment procedure, for example, if the PIT tag fails to properly deploy from the needle. As a result, practitioners may find it difficult or impossible to locate the implanted PIT tag using imaging techniques such as ultrasound or magnetic resonance imaging (MRI) and / or to easily identify the implanted PIT tag using a single image view. In addition, if a PIT tag is used to mark the location of a structure, structural abnormality, or area within tissue and migrates away from the target location, it may be difficult to identify the structure, abnormality, or area within the tissue even when the PIT tag is located. Implanted PIT tags with low tactility (i.e., more difficult for a practitioner to locate by palpating the tag within the surgical cavity) may be more difficult or require more time for a practitioner to locate during a surgical procedure, e.g., when removing the PIT tag along with a tumor or sentinel lymph node. Thus, a need exists for implanted PIT tags and deployment procedures that provide improved reliability, fixation, visibility, and / or palpability for the practitioner. Summary of the Invention [Means for solving the problem]

[0007] With these and other circumstances in mind, the present disclosure provides methods, systems, and devices for preventing transponder tag migration and increasing their detectability.

[0008] In one aspect of the present disclosure, a marking system for implantation into tissue includes a marker body having an outer surface, the marker body including a transponder configured to respond to electromagnetic radiation from an external source and a microchip operatively connected to the transponder and configured to activate in response to the electromagnetic radiation; and an anti-migration device configured to receive at least a portion of the marker body, engage tissue into which the marker body is to be implanted, and resist migration of the marker body after implantation.

[0009] In another aspect of the present disclosure, a deployment system includes a deployment device including a handle portion including an actuator configured to cause a deployment action, and a cannula, the cannula attached to the handle portion at a first end of the cannula and terminating in a cannula end at a second end of the cannula opposite the first end; and a marking system disposed within a lumen of the cannula, the marking system including a marker body having an outer surface, the marker body including a transponder configured to respond to electromagnetic radiation from an external source and a microchip operatively connected to the transponder and configured to activate in response to the electromagnetic radiation; and an anti-migration device configured to resist migration of the marker body after implantation of the marking system into tissue.

[0010] In another aspect of the present disclosure, a method of marking a target location within a patient's body includes positioning a distal end of a cannula adjacent the target and below a tissue surface, with a tissue marker and an anti-migration device disposed within a lumen of the cannula; deploying the tissue marker and anti-migration device at the target location; and expanding a portion of the anti-migration device to engage tissue at the target location to anchor the tissue marker at the target location.

[0011] In another aspect of the present disclosure, a localization marker device for implantation into tissue includes an implantable marker having a body with an outer surface, the implantable marker being a transponder, a reflector, an active marker, a magnetic marker, a radioactive seed, a Doppler marker, a passive marker, a wireless tumor localization implant, or a combination thereof, and an anti-migration device configured to at least partially engage the outer surface of the body and provide migration resistance to the implantable marker after deployment.

[0012] Additional aspects of the present disclosure will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the present disclosure. The aspects of the present disclosure and the advantages arising therefrom may be realized and attained by means of the elements and combinations particularly pointed out in the appended claims and their equivalents.

[0013] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure and claims. [Brief explanation of the drawings]

[0014] These and other aspects of the present disclosure will be described with reference to the accompanying drawings.

[0015] [Figure 1] FIG. 1 illustrates a side view of an exemplary PIT tag according to various aspects of the present disclosure.

[0016] [Figure 2A] 2A, 2B, and 2G each illustrate a cross-sectional view of an exemplary anti-migration device according to various aspects of the present disclosure. [Figure 2B] 2A, 2B, and 2G each illustrate a cross-sectional view of an exemplary anti-migration device according to various aspects of the present disclosure. [Figure 2C] 2C-2F and 21 each illustrate a side view of an exemplary anti-migration device according to various aspects of the present disclosure.

[0017] [Figure 2D] 2C-2F and 21 each illustrate a side view of an exemplary anti-migration device according to various aspects of the present disclosure. [Figure 2E] 2C-2F and 21 each illustrate a side view of an exemplary anti-migration device according to various aspects of the present disclosure. [Figure 2F] 2C-2F and 21 each illustrate a side view of an exemplary anti-migration device according to various aspects of the present disclosure. [Figure 2G] 2A, 2B, and 2G each illustrate a cross-sectional view of an exemplary anti-migration device according to various aspects of the present disclosure.

[0018] [Figure 2H] 2H and 2J illustrate perspective views of an exemplary anti-migration device according to various aspects of the present disclosure. [Figure 2I] 2C-2F and 21 each illustrate a side view of an exemplary anti-migration device according to various aspects of the present disclosure. [Figure 2J] 2H and 2J illustrate perspective views of an exemplary anti-migration device according to various aspects of the present disclosure.

[0019] [Figure 3] 3A and 3B each illustrate a schematic diagram of an exemplary implantation device according to various aspects of the present disclosure.

[0020] [Figure 4] FIG. 4 illustrates a process flow of an exemplary loading method according to various aspects of the present disclosure.

[0021] [Figure 5] 5A-5C each illustrate a schematic diagram of the exemplary loading method of FIG.

[0022] [Figure 6]6A and 6B each illustrate a schematic diagram of an exemplary implantation method according to various aspects of the present disclosure.

[0023] [Figure 7] 7A and 7B each illustrate a schematic diagram of another exemplary implantation device according to various aspects of the present disclosure.

[0024] [Figure 8] FIG. 8 illustrates a process flow of another exemplary loading method according to various aspects of the present disclosure.

[0025] [Figure 9] 9A-9D each illustrate a schematic diagram of the exemplary loading method of FIG.

[0026] [Figure 10] 10A and 10B each illustrate a schematic diagram of another exemplary implantation method according to various aspects of the present disclosure.

[0027] [Figure 11] 11A and 11B each illustrate a schematic diagram of another exemplary implantation device according to various aspects of the present disclosure.

[0028] [Figure 12] 12A and 12B each illustrate a schematic diagram of another exemplary implantation method according to various aspects of the present disclosure.

[0029] [Figure 13] 13A and 13B each illustrate a schematic diagram of another exemplary implantation method according to various aspects of the present disclosure.

[0030] [Figure 14-1] 14A-14D each illustrate a perspective view of an exemplary sheathed tag according to various aspects of the present disclosure.

[0031] [Figure 14-2]14E-14L each illustrate a side view of an exemplary sheathed tag according to various aspects of the present disclosure. [Figure 14-3] 14E-14L each illustrate a side view of an exemplary sheathed tag according to various aspects of the present disclosure.

[0032] [Figure 14-4] 14M and 14N illustrate perspective views of exemplary sheathed tags according to various aspects of the present disclosure.

[0033] [Figure 14-5] 14O and 14P illustrate perspective and end views, respectively, of another exemplary sheathed tag according to various aspects of the present disclosure.

[0034] [Figure 14-6] 14Q and 14R illustrate perspective and end views, respectively, of another exemplary sheathed tag according to various aspects of the present disclosure.

[0035] [Figure 14-7] 14S and 14T illustrate perspective and end views, respectively, of yet another exemplary sheathed tag according to various aspects of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0036] PIT tags can be used to locate or identify tumors, lesions, body structures, or abnormalities within a patient's tissue. For example, a PIT tag can be positioned within a patient's breast to mark a lesion for surgical removal and, if necessary, neoadjuvant therapy prior to surgical removal. The tag can be placed within breast tissue within about 6 cm of the breast surface to mark a lesion intended for surgical removal or other treatment. The tag can be surgically removed once treatment is complete, or in some cases, can remain permanently within the patient.

[0037] As described above, PIT tags implanted within a patient can migrate over time, thus causing the implanted PIT tag to move from its expected location at the time of implantation. Migration can occur immediately after deployment, after treatment such as neoadjuvant therapy, or over time after other procedures. While the location of the PIT tag can be detected using a handheld probe or reader (e.g., with a sensor used to localize the signal emitted by the PIT tag) and, in some cases, visually (e.g., via ultrasound, X-ray, and / or MRI), PIT tag migration can make the process of locating an implanted PIT tag more difficult and may require, for example, the clinician or surgeon to take additional measures to locate the area the PIT tag was originally intended to mark for treatment. Prior to the deployment process, the PIT tag risks becoming dislodged from the deployment system during storage. The deployment process itself may also not proceed properly if the PIT tag remains embedded within the deployment needle shaft. Additionally, deployment may be more difficult (e.g., due to patient discomfort, increased risk of injury or scarring, etc.) if the cannula of the deployment system is not made as thin as possible. Such systems require the PIT tag to have a small profile (e.g., 2 mm), and in some situations, the shape and small profile of the PIT tag may make it difficult to identify the tag using a single image view, for example, in mammography.

[0038] Thus, a need exists for implantable PIT tags and deployment procedures that provide improved reliability, retention, visibility, and / or tactility for practitioners. A need also exists for a deployment system in which PIT tags or other implantable objects are securely retained during storage and reduce the risk of adverse effects to the patient. The present disclosure provides a marking system in which a PIT tag is combined with an anti-migration feature or component (e.g., a sheath or wire, as will be described in more detail below) to prevent migration of the PIT tag from the target location. The anti-migration feature or component may be a structure that changes the effective size and / or shape and / or outer contour of the PIT tag and may be formed, at least in part, from a material that is visible under inspection by one or more imaging modalities, such as ultrasound. The anti-migration feature or component may have a low-profile profile within the cannula and, due to its material properties, expand upon deployment to prevent the assembly from migrating. Thus, the present disclosure provides systems and methods that address the factors described above and provide practitioners with reliable deployment of implantable PIT tags, improved anchoring and anti-migration properties, increased visibility under various imaging techniques, and improved palpability.

[0039] This disclosure provides several example use cases for the disclosed systems, methods, devices, and apparatus. Particular use cases are presented in the fields of breast imaging and / or lumpectomy, but the disclosure is not so limited. In general, the systems, methods, devices, and apparatus described herein may be applied in any situation where an object is buried beneath a surface and it would be beneficial to reduce or prevent migration of the buried / implanted object, improve the reliability of the deployment procedure, and / or improve the detectability of the object after deployment. For example, although the following detailed description is presented with respect to implanting a PIT tag, in practice the following description may be implemented as systems, methods, and apparatus for implanting an implantable object, loading or otherwise preparing an implantable object deployment system, and deploying the implantable object from the deployment system, where the implantable object is an object other than a PIT tag, such as a localization marker, which may include, but is not limited to, a transponder, a reflector, other active marker, a magnetic marker, a radioactive seed, a Doppler marker, other passive marker, and / or other wireless ("wireless") tumor-localization implant (including combinations thereof). Each of these types of implantable objects may be implanted by inserting a cannula near the target location (i.e., a lesion or tumor), deploying the implantable object from the cannula as described below, and removing the cannula; therefore, these implantable objects may similarly be prone to migration after implantation, as described above. Thus, references below to a "PIT tag" may be understood to apply generally to any implantable object, and the present disclosure is generally applicable to marking systems for implantation into tissue, the marking system including a body to be implanted and an anti-migration device for preventing migration of the body.

[0040] FIG. 1 illustrates an exemplary marker body, designated as a PIT tag 100 according to the present disclosure, which may be an example of a body component of a marking system according to the present disclosure. The PIT tag 100 includes a PIT 102 attached to a microchip 104 operatively connected to the PIT 102, both of which are encapsulated within an implantable shell 106 that defines the exterior surface of the PIT tag 100. The PIT 102 is a passive device without any battery or other power source; therefore, the microchip 104 remains inactive until energized by electromagnetic radiation (e.g., radio or other low-frequency energy) from an external source, such as a locator device. The microchip 104 within the PIT tag 100 may be pre-recorded with a unique code, such as an alphabetic, numeric, or alphanumeric code, which may serve, for example, to identify a patient and / or a surgical procedure to be performed. The PIT 102 includes an induction coil that responds to external signals at the induction coil's resonant frequency, thereby providing and obtaining the power needed to interrogate the microchip 104 and respond with its unique code back to the source of the external signal (e.g., a locator device), thereby positively identifying the PIT tag 100 and providing its approximate location within the patient.

[0041] To enable the PIT tag 100 to be implantable within a patient, the implantable shell 106 may be made from a material that is sterilizable. In one example, the implantable shell 106 is capable of undergoing ethylene oxide (ETO) sterilization, although other types of sterilization may be possible or appropriate. The implantable shell 106 may also be strong and / or durable enough to enable implantation for a desired period of time, such as up to 30 days. In some implementations, the PIT tag 100 and the implantable shell 106 may be permanently implantable. The implantable shell 106 may be made from a material that resists cracking or splitting. The material may be biocompatible. The implantable shell 106 may be made from a material that is transparent to radio or other low frequencies, at least in the range of the resonant frequency of the PIT 102 and / or the response frequency of the microchip 104. The implantable shell 106 may be made from, for example, glass or plastic. In some examples, at least one of the PIT 102, the microchip 104, and the implantable shell 106 may be visible under ultrasound examination. The implantable shell 106 must also be sized (e.g., diameter, length, or both) to allow the PIT tag 100 to fit within a cannula or other device used to implant the PIT tag 100. In the particular example illustrated in FIG. 1 , for example, the implantable shell 106 has a length of approximately 11 mm (0.4 inches) and a maximum diameter of approximately 2 mm (0.07 inches). As illustrated in FIG. 1 , the implantable shell 106 has a two-part construction, although a one-piece shell is also envisioned.

[0042] 1 illustrates the implantable shell 106 as a generally smooth cylinder, one or more components having surface features can be utilized to increase the PIT tag 100's resistance to migration, for example, by increasing the effective surface area of ​​the implantable system and therefore increasing the frictional forces that would need to be overcome before any migration of the implantable system can occur. The surface features can be incorporated directly into the design of the implantable shell 106, for example, by groove machining, or the surface features can be incorporated as a separate element or sheath, referred to herein as an anti-migration device, that engages or receives the shell 106 either before or after implantation of the PIT tag 100, resulting in a final implanted PIT assembly with anti-migration properties. The anti-migration device can comprise a structure that alters the effective size and / or shape and / or outer contour of the PIT tag (shell 106) to prevent migration or migration of the PIT tag from its implanted or deployed position. Thus, the anti-migration device may be comprised of a portion having an inner surface that conforms at least to some extent to the outer surface of the PIT tag, and a portion having an outer surface that expands at least to some extent or otherwise changes the effective outer contour, size, or shape of the outer surface of the PIT tag when the tag is deployed and positioned within a patient's tissue. The inner and outer surfaces described above may be on different portions of the anti-migration device or on the same portion of the anti-migration device. In some exemplary embodiments, the anti-migration device may include structures that act as barbs or anchors to engage tissue, may include portions that expand to compress against tissue to resist migration, may include portions that provide increased friction against tissue to resist migration, etc. For example, the anti-migration device may include a nitinol wire with one or more barbs.

[0043] The surface features may also include elements that aid in detection and location of the anti-migration device by touch (e.g., a flanged portion, a portion with an easily identifiable shape such as a ball or sphere), or under one or more imaging techniques (e.g., a portion made from a material that is highly visible under MRI, X-ray imaging, ultrasound, etc.). In some implementations, a single feature may be both an anti-migration and a detection and location feature, both an anti-migration and an imaging feature, or all three: an anti-migration, a detection and location, and an imaging feature. For example, the surface feature may include a ball that, when implanted, engages tissue to prevent migration of the PIT tag 100, while simultaneously improving the tactility of the marking system.

[0044] In addition to, or as an alternative to, barbs, protrusions, or anchor-type surface features, the surface features may result in portions of the marking system having a relatively large diameter when implanted (e.g., providing an expansion force against tissue in a radial direction) and portions of the implanted system having a relatively small diameter. In some exemplary embodiments, the surface features may be implemented as an anti-migration device having a generally hourglass or bowtie shape, with larger diameter portions located at the ends of the sheath in the axial (longitudinal) direction (and thus positioned toward the respective ends of the shell 106) and smaller diameter portions located axially in the center of the sheath. Some examples of anti-migration devices shaped to increase the resistance to movement of the marking system are described herein and include anti-migration devices with larger diameter portions as shown in Figures 2A-2F, 13E, 13H, and 13K, anti-migration devices with radial protrusions as shown in Figures 2G, 13A-13B, 13D, 13G-13F, 13I-13J, and 13M, and anti-migration devices with pointed points as shown in Figures 2G and 13L-13M.

[0045] As described in the examples herein, the shape of the shell 106 and / or anti-migration device may have a circular cross-section, which allows for comparison of cross-sectional diameters obtained along various axial locations of the device. It should be appreciated that the present disclosure contemplates that the PIT tag and / or anti-migration device may have different shapes when viewed in cross-section, including, but not limited to, an oval, a triangle, a square, a higher-order regular polygon, a concave polygon such as a star with any number of points, or combinations thereof. In such cases, the resulting cross-section would be sized correspondingly along the axial length of the anti-migration device.

[0046] Anti-migration devices according to the present disclosure can be formed from non-absorbable materials so that they can remain in tissue for relatively long periods of time without degradation or interaction with adjacent tissue. In other implementations, anti-migration devices can be formed from absorbable materials that can enhance tissue ingrowth. Anti-migration devices according to the present disclosure can also be designed to improve detectability (e.g., improved ultrasound visibility, improved tactility, etc.). For example, to aid visibility during ultrasound examinations using medical ultrasound at frequencies ranging from 1 megahertz (MHz) to 40 MHz in intensity modulation mode, the anti-migration device can have a braided, woven, mesh, or web-like structure. Web parameters, such as the web-like body diameter (or width and thickness), number of webs, web density, and web material, can be selected to match the acoustic energy of incident ultrasound radiation. Ultrasound visibility can be further improved by roughening the web-like body, such as by sandblasting. Visibility can also or alternatively be improved by coating the web-like body. The coating can be a nanocoating, such as gold nanoparticles. For example, to aid in visibility during X-ray imaging in mammography, the anti-migration device can be formed from a material that provides good visibility under X-ray examination. Thus, the web-like body can be formed from a metal or metal alloy, for example, by metal wire or by metal particles embedded in plastic. The metal can exhibit magnetic properties that can improve visibility under MRI examination. The metal or metal alloy can include titanium, gold, and / or iron. In one specific example, the anti-migration device is formed from a titanium alloy, such as nitinol.

[0047] The anti-migration device may alternatively be formed from a material that allows for manufacturing using injection molding methods. Thus, in addition to metal, the anti-migration device may also be formed from plastic or rubber materials, including, but not limited to, silicone, ethylene propylene diene monomer (EPDM), thermoplastic elastomer (TPE), polyether ether ketone (PEEK), or polypropylene (PP). In some implementations, some wires of the web-like body may be formed from metal, while other wires of the web-like body are formed from plastic or rubber. Such materials may also provide shape memory benefits, thus allowing the anti-migration device to exist in a compressed state (e.g., within the cannula of an implantation device) for extended periods of time and retain the ability to resume its expanded state upon implantation. The anti-migration device may therefore be designed to achieve elastic compression under a radial force of at least 1 Newton (N); thereafter, upon implantation in its elastically compressed state, the anti-migration device may independently transition to its expanded state and retain this state as long as the surrounding tissue exerts a radial force of 1 N or less (e.g., 0.1 N) on the anti-migration device. The anti-migration device may have a first size and a first shape in the compressed state and a second size and a second shape in the expanded state, where the first size may differ from the second size and / or the first shape may differ from the second shape. However, as will be described in more detail below, in some implementations, the anti-migration device may include geometric features that cut into the tissue while the implant is being pushed out of the cannula, which may further reduce (or even eliminate) the required radial force. In its compressed state, the outer diameter of the anti-migration device may be small enough to allow the anti-migration device to reside in the same cannula as a PIT tag. In its expanded state, the inner diameter of the anti-migration device can be large enough to allow the PIT tag to be retained by the anti-migration device.

[0048] The anti-migration device may be made from a material that is sterilizable (e.g., capable of undergoing ETO sterilization) to allow the anti-migration device to be implantable. The anti-migration device should also be strong and / or durable enough to allow implantation for a desired period of time. In some implementations, the PIT tag 100 and the implantable shell 106 may be permanently implantable. In implementations where the anti-migration device is large enough that it covers the RF-responsive portion of the PIT tag 100 in the deployed state, the anti-migration device may be made from a material that is transparent to radio or other low frequencies.

[0049] 2A-2J illustrate exemplary anti-migration devices 200a-200j, respectively, according to the present disclosure (collectively referred to as "anti-migration devices 200" when it is not necessary to distinguish between them. Figures 2A, 2B, and 2G show cross-sectional views, while Figures 2C-2F and 21 show side views, and Figures 2H and 2J each show a perspective view.

[0050] As shown in FIG. 2A , the anti-migration device 200a includes a small diameter portion 202a located approximately at its center in the axial (length) direction and two large diameter portions 204a located at each end of the anti-migration device 200a. The small diameter portion 202a may be sized to frictionally engage a marking element (e.g., a PIT tag, as will be described in more detail below) received within the anti-migration device 200a. The large diameter portion 204a may be sized to provide a frictional anti-migration force to resist movement in a medium (e.g., tissue, as will be described in more detail below) in which the anti-migration device 200a is embedded, thereby acting as an anti-migration feature. As embodied in FIG. 2A , each end of the anti-migration device 200a may terminate at multiple points, shown as eight points in FIG. 2A . In the illustrated example, the anti-migration device 200a is generally rotationally symmetric, has a generally circular footprint when viewed from the front (ie, from a plane perpendicular to the axial direction), and has a generally web-like structure.

[0051] 2B illustrates an anti-migration device 200b that is similar to anti-migration device 200a in that it includes at least a small diameter portion 202b located approximately axially at its center and two large diameter portions 204b located at each axial end of it. Small diameter portion 202b is sized to frictionally engage a marking element received within anti-migration device 200b, and large diameter portions 204b are sized to provide a frictional anti-migration force to resist movement in a medium in which anti-migration device 200b is embedded.

[0052] FIG. 2C illustrates an anti-migration device 200c that also includes a small diameter portion 202c located approximately axially at its center and two large diameter portions 204c located at opposite axial ends of the component. The small diameter portion 202c is also sized to frictionally engage a marking element received within the anti-migration device 200c, and the large diameter portion 204c is sized to provide a frictional anti-migration force to resist movement in the medium in which the anti-migration device 200c is embedded. If the frictional force is not sufficient to secure the marking element within the small diameter portion 202c, adhesives or other fastening methods may be used. As also shown in the embodiment of FIGS. 2A and 2B, the end portions of the anti-migration component 200c may include several points (12 as shown). The number of end points provided on each axial end (large diameter portion 204c) may vary depending, for example, on the size of the end, the number of wires or webs forming the end, the type of material used, etc. A greater number of end points may provide increased anti-migration properties compared to anti-migration devices with fewer end points, for example, by increasing the number of contact points between the sheath and tissue and / or by increasing the sheath's expansion force. A greater number of wires in the braid may also increase visibility under ultrasound imaging. Furthermore, in one exemplary embodiment, each large diameter end portion has an end feature 206c, which in the illustrated example is ball-shaped. The end feature 206c may be formed by welding or twisting adjacent wires of the anti-migration device 200c. The end feature 206c may be of various shapes and / or sizes and may provide improved tactility for the practitioner.

[0053] 2D includes a central neck 208d that may help maintain the diameter of the small diameter portion 202d. The central neck 208d may further help maintain the structural integrity of the anti-migration device 200d, such as by holding individual wires together in a clamped manner. The central neck 208d may be formed from the same material as the anti-migration device 200d or from a different material, and may include air / gas inclusions to increase visibility under ultrasound imaging.

[0054] Anti-migration devices 200a-200b are formed by laser cutting tubing, while anti-migration devices 200c-200d are generally formed by braiding wires. Anti-migration device 200e, shown in FIG. 2E, is formed by welding wires together at their intersections. This may improve the stiffness of anti-migration device 200e in its expanded state, such that a relatively consistent transition between small diameter portion 202e and large diameter portion 204e is achieved.

[0055] As an alternative to the webbed / braided / woven body design of anti-migration devices 200a-200e, anti-migration devices 200f and 200i illustrated in Figures 2F and 21 have a helical design. Referring to the embodiment of Figure 2F, the helical body of anti-migration device 200f includes a small diameter portion 202f located approximately at its axial center and two large diameter portions 204f located at each axial end of anti-migration device 200f. Thus, each of anti-migration devices 200a-f illustrated in Figures 2A-2F has a form factor that is generally hourglass-shaped in side view (or each funnel-shaped portion has two funnel-shaped portions that taper from a larger axial cross-section to a smaller axial cross-section at the center of the anti-migration device, which may also be considered an hourglass shape as used in this disclosure). The anti-migration device 200 according to the present disclosure may be formed with a cone angle (i.e., the angle between the axis and the cone surface) of 25° to 50°, particularly 30° to 45°. When the web-like shape is formed by braiding wires, the wire diameter is less than 0.5 mm (0.02 inches), for example, it may be 0.1 mm (0.004 inches) or less, and in one particular example, it is 0.04 mm (0.016 inches) to 0.10 mm (0.0039 inches). Wire diameters within these ranges may improve the compressibility of the anti-migration device 200 while also improving the expansion force of the anti-migration device 200, allowing it to expand against tissue pressures that may be prevalent in hard tissues such as tumor tissue.

[0056] Referring to the embodiment of FIG. 2I, in contrast to anti-migration device 200f, anti-migration device 200i includes a helical body including a large diameter portion 202i located axially along the middle portion of anti-migration device 200i and two small diameter portions 204i located at each axial end of anti-migration device 200i. In such an embodiment, the helical body can be formed from one or more wires (one wire is shown in the embodiment of FIG. 2I) made of a shape-memory material such as nitinol. In this manner, when anti-migration device 200i is pushed out of a delivery device (e.g., a cannula), as described further below, the middle portion of the anti-migration device self-expands to form large diameter portion 202i (i.e., to prevent migration of a PIT tag held within anti-migration device 200i), while each of the small diameter portions 204i tightly grips the rounded end of a PIT tag (see, e.g., FIGS. 14O-14T).

[0057] As an alternative to the flared body designs of anti-migration devices 200a-200f, anti-migration device 200g illustrated in FIG. 2G has a more cylindrical design with tines or protrusions, anti-migration device 200h illustrated in FIG. 2H has a cap-like design, and anti-migration device 200j illustrated in FIG. 2J has a cylindrical design with cutouts formed by micro-injection molding and / or laser cutting. Anti-migration devices 200g and 200h are configured to provide a slimmer profile than the embodiments of, for example, FIGS. 2A-2F and are therefore not intended to expand or otherwise change shape upon deployment. The use of a shape-nonchanging design allows for the use of a wider range of materials for anti-migration devices 200g, 200h compared to anti-migration devices 200a-200f. Anti-migration device 200j utilizes processes such as micro-injection molding and laser cutting, as well as additional materials such as, for example, plastic materials, as described further below.

[0058] As shown in FIG. 2G, the anti-migration device 200g includes a hollow body 210g defining an interior 212g of the anti-migration device 200g. The hollow body 210g is composed of external protrusions 204g extending from the outer surface of the hollow body 210g and internal protrusions 202g extending from the inner surface of the hollow body 210g into the interior 212g. The interior 212g is sized to receive a marking element, and the internal protrusions 202g can frictionally engage the marking element when positioned within the interior 212g. The internal protrusions 202g can extend radially from the inner surface toward the central axis of the anti-migration device 200g, form any pattern, and include any number of protrusions. The internal protrusions 202g can extend perpendicularly and / or at an angle from the inner surface of the hollow body 210g. Similarly, the external protrusions 204g may extend radially outward from the outer surface, form any pattern, and include any number of protrusions. The external protrusions 204g may be positioned to engage tissue surrounding the hollow body 210g after implantation and may include pointed ends to promote engagement to resist migration of the anti-migration device 200g once implanted. The external protrusions 204g may extend perpendicularly and / or at an angle from the outer surface of the hollow body 210g. The external protrusions 204g and / or internal protrusions 202g may be produced by cutting (e.g., laser cutting) a U, V, or similar shape into the outer or inner surface of the hollow body 210g. Although two external protrusions 204g and two internal protrusions 202g are illustrated in FIG. 2G , in practical implementations, the anti-migration component 200g may include additional or fewer external protrusions 204g and / or internal protrusions 202g. The external protrusions 204g and / or internal protrusions 202g may be regularly or irregularly spaced circumferentially. As shown in FIG. 2G , one end of the anti-migration device 200g terminates in a sharp point 214g, which may function as a cannula to improve penetration into hard tissues such as tumors, cartilage, or bone. FIG. 2G illustrates the anti-migration device 200g in its expanded state (i.e., after implantation) with the external protrusions 204g in a radially extending position.Prior to implantation, the external protrusions 204g may be in an axially extending position, whereby the external protrusions 204g move from the axially extending position to the radially extending position during implantation.

[0059] The cap-like anti-migration device 200h can partially or completely receive a marking element, such as a PIT tag, within the hollow body 210g that forms the anti-migration device 200h. The marking element can be secured to the hollow body 210g in a heated state so that the hollow body 210g retains the marking element in an airtight manner after the anti-migration device 200h has cooled. Such an attachment procedure allows for secure attachment without glue or other adhesives. The anti-migration device 200h further includes multiple side holes 216h that can aid in mounting, although only one side hole 216h is visible in the perspective view of FIG. 2H.

[0060] 2J, the plastic structure 202j of the anti-migration device 200j, which includes a plurality of cutouts 203j that form a plurality of barbs 204j, can be fabricated using, for example, a micro-injection molding process. While it is difficult to store most plastic materials under tension (e.g., Nitinol) because over time the plastic material will take the shape of the structure in which it is stored (i.e., thereby making self-expansion impossible), the plastic structure 202j illustrates a design that overcomes this problem.

[0061] For example, in such an embodiment, the barbs 204j are configured to be in a tensioned state when the anti-migration device 200j is elongated (e.g., the anti-migration device 200j can be pre-tensioned via stops on the tongues of the cannula when the anti-migration device 200j is loaded into the cannula), so that the barbs 204j expand radially outward when the anti-migration device 200j is released from the cannula. Thus, the plastic structure 202j is immediately pre-tensioned within the cannula during implantation, and the pre-tension is secured by a locking mechanism exemplified by the barbs 204j. The cylindrical plastic structure 202j is compressed, for example, until the hooks 204j snap into place, and the posts inside the cannula elastically deform along the inner wall of the cannula. In this manner, when the pre-stressed anti-migration device 200j is released from the cannula, the struts rise up, increasing the volume of the anti-migration device 200j, such that the anti-migration device 200j can no longer fit through the puncture channel (i.e., created by the cannula). Those skilled in the art will understand that the cutouts 203j and formed plastic barbs 204j depicted in the embodiment of FIG. 2J are exemplary only, and that contemplated anti-migration devices 200j may include cutouts 203j of various shapes and sizes that form barbs 204j having various shapes and sizes and create a variety of different patterned structures 202j.

[0062] In the expanded state, the maximum outer diameter of anti-migration devices 200a-200f, 200i, and 200j according to the present disclosure (e.g., the outer diameter of large diameter portions 204a-204f) can be less than 10 mm (0.4 inches), in some cases less than 8 mm (0.3 inches), and in exemplary embodiments, is between 3.0 mm (0.12 inches) and 5.0 mm (0.20 inches). Such a diameter maintains good visibility under some imaging methods while maintaining sufficiently small space requirements for foreign bodies within tissue. Even in the expanded state, the minimum inner diameter of anti-migration devices 200a-200f, 200i, and 200j according to the present disclosure (e.g., the inner diameter of small diameter portions 202a-202f, 200i, and 200j) can be approximately equal to the outer diameter of a marking element, such as a PIT tag 100, to enable the anti-migration device 200 to retain the PIT tag 100 therein. On the other hand, in a compressed state, the outer diameter of the anti-migration devices 200a-200f, 200i, and 200j should be only slightly larger than the outer diameter of a marking element, such as the PIT tag 100. The anti-migration devices 200a-200f, 200i, and 200j may have an outer diameter of 3 mm (0.1 inches) or less, and in some exemplary embodiments, about 2 mm (0.08 inches) or less. The anti-migration device 200 may also have a wall or braid thickness of 0.3 mm (0.01 inches) or less, for example, 0.1 mm (0.004 inches). In one particular example, the PIT tag 100 may have an outer diameter of 1.41 mm (0.0555 inches), and the anti-migration device 200 has a wall thickness of 0.1 mm (0.0004 inches) and a minimum diameter of 1.61 mm (0.634 inches) in a compressed state. In embodiments in which the anti-migration device, such as anti-migration component 200g, 200h, does not change shape or size, the outer diameter of the anti-migration device should be only slightly larger than the outer diameter of the marking element, such as PIT tag 100. The anti-migration device 200g, 200h may have an outer diameter of 3 mm (0.1 inch) or less, and in some exemplary embodiments, about 2 mm (0.08 inch) or less.The minimum inner diameter of the anti-migration device 200g, 200h according to the present disclosure (e.g., the inner diameter of the hollow body 210g, 210h) may be approximately equal to the outer diameter of a marking element such as the PIT tag 100, so as to enable the anti-migration device 200 to retain the PIT tag 100 therein.

[0063] The individual elements of the anti-migration device 200 may be selected and combined. For example, an anti-migration device 200 according to the present disclosure may include both end features (similar to end feature 206c illustrated in FIG. 2C ) and a central draw (similar to central draw 208d illustrated in FIG. 2D ). In another example, an anti-migration device 200 according to the present disclosure may have an overall form factor similar to anti-migration device 200a or 200b, but with more end points than anti-migration device 200c or 200d. In yet another example, an anti-migration device 200 according to the present disclosure may be combined with a cap-like anti-migration device 200h illustrated in FIG. 2H . For example, if the anti-migration device 200 is formed from wire, the wire can be fused into the surface of the anti-migration device 200h to provide a more secure attachment.

[0064] Also, while the anti-migration devices 200a-j illustrated in Figures 2A-2J are generally circular (i.e., have a circular axial cross-section) when viewed axially, anti-migration devices 200 according to the present disclosure may have different axial cross-sectional shapes, including, but not limited to, ovals, triangles, squares, higher-order regular polygons, concave polygons such as stars with any number of points, or combinations thereof. In some implementations, the axial cross-sectional shape may be irregular (e.g., asymmetrical). Individual faces of the axial cross-sectional shape may be generally linear, curved, curvilinear, or a combination thereof. Other possible shapes for the anti-migration device 200 are illustrated in Figures 11A-D (in the deployed state) and will be described in more detail below.

[0065] Although each of the anti-migration devices 200a-200j is illustrated as being of a generally unitary structure, an anti-migration device 200 according to the present disclosure may be formed from two or more separate portions. For example, an anti-migration device 200 according to the present disclosure may be formed from two portions, each of which has a smaller diameter portion 202 at one end and a larger diameter portion 204 at the other end. The two portions may be arranged front to back, with the smaller diameter portions 202 facing toward each other and the larger diameter portions 204 facing away from each other. In such an arrangement, the center of the combined portions will generally be smaller in diameter than the ends of the combined portions.

[0066] According to the present disclosure, a marking element, such as a PIT tag (e.g., PIT tag 100 illustrated in FIG. 1 ), and an anti-migration device (e.g., any of anti-migration devices 200a-200j illustrated in FIGS. 2A-2J ) can be implanted substantially simultaneously. Generally, a method of implanting a PIT tag (or other implantable marker object) according to the present disclosure can include providing a deployment system (also referred to as an implantation system), inserting a cannula end of the deployment system into a deployment site below a tissue surface, actuating a drive element of the deployment system to apply a force to the implantable object and / or the anti-migration device toward the cannula end, and thus implanting the implantable object at the deployment site such that at least a portion of the implantable object is contained within the anti-migration device.

[0067] 3A-3B illustrate a first exemplary implantation system 300 according to the present disclosure in a ready-to-deploy state. The implantation system 300 includes a deployment device including a handle portion 302 and a cannula 304 including a lumen in which a deployment package 314 is disposed.

[0068] The handle portion 302 includes a deployment button 308 or other actuator that operates a plunger 310, which in turn operates a drive element 312. The handle portion 302 and one or more of its components may be manufactured from a suitable plastic. The deployment button 308 is connected to a housing of the handle portion 302 and is actuatable by a user, such as a surgeon. The deployment button 308 may be physically depressed (or moved) or may be a soft button configured to generate an electrical or electronic signal when activated. The cannula 304 extends a distance away from the handle portion 302 and terminates in a cannula tip 306. The cannula 304 may be formed from a suitable metal. The cannula 304 may range from 25 mm (1 inch) to 200 mm (8 inches), and in some exemplary embodiments, has a length that is from 50 mm (2 inches) to 150 mm (6 inches). The length of the cannula 304 affects the extent of the implantation system 300's accessibility to tissue sites within a subject's body. A cannula 304 of a longer length may be used when adjustment assistance (e.g., for stereotactic techniques) is used. The cannula 304 terminates in a cannula tip 306. The inner diameter of the cannula 304 may closely match the outer diameter of the deployment package 314, which may be approximately 0.15 mm (0.006 inches). For purposes of explanation, the direction of the cannula tip 306 is referred to herein as the "distal" direction, and the direction of the handle portion 302 is referred to herein as the "proximal" direction.

[0069] A drive element 312 extends through the cannula 304. When the deployment button 308 is actuated, the plunger 310 operates to move the drive element 312 axially within the cannula 304. The drive element 312 may be formed from wire or a sufficiently stable plastic fiber. As a result, the drive element 312 may be moved along a linear, guided slide path between a preloaded position and a deployed position. In the deployed position, force from the plunger 310 is transmitted to a preloaded deployment package 314 at a location near the cannula tip 306. Thus, when the deployment button 308 is actuated, the deployment package 314 may be driven out of the cannula 304 by the axial movement of the drive element 312 to a tissue site at the location of the cannula tip 306. This may be achieved by having drive element 312 coaxially aligned with cannula 304, thus pushing pre-loaded deployment package 314 past cannula tip 306 and out of cannula 304. An example of deployment package 314 is shown in more detail in inset B, which corresponds to FIG.

[0070] In FIG. 3B , the drive element 312 is in a preloaded position. The deployment package 314 includes a PIT tag 316 distal to the drive element 312 and proximal to the anti-migration device 318, and an anti-migration device 318 distal to the drive element 312 and PIT tag 316 and proximal to the cannula tip 306. The PIT tag 316 may be, for example, the PIT tag 100 illustrated in FIG. 1 . As an alternative to the configuration shown in FIG. 3B , the deployment package 314 of FIG. 3A may be formed with the PIT tag 316 already disposed within the anti-migration device 318, as described in more detail below with respect to FIGS. 11A-11B . However, by comparison, the configuration shown in FIG. 3B may enable the use of a cannula having a smaller diameter. The anti-migration device 318 may be, for example, any of the anti-migration devices 200a-200h illustrated in FIGS. 2A-2H or modifications or alternatives thereto as described above. The anti-migration device 318 is in a compressed state. Due to the pre-stress, the anti-migration device 318 (and therefore the PIT tag 316) maintains its position within the cannula 304.

[0071] FIG. 4 illustrates an exemplary process flow for preloading a deployment package 314 into a deployment system 300. For purposes of explanation, the process flow will be described in the context of the deployment system 300 illustrated in FIGS. 3A-B. In this illustration, various processes within the process flow are illustrated in FIGS. 5A-5C. In operation 410, the process flow includes placing the drive element 312 in a preloaded position. Operation 410 may include activating a button, such as the deployment button 308 or a reset / back button (not shown). If the drive element 312 is already in the preloaded position, operation 410 may be omitted. Next, in operation 420, the PIT tag 316 is loaded into the cannula 304. The PIT tag 316 may be loaded through the cannula tip 306 or, if the proximal end of the cannula 304 is accessible, through the proximal end (e.g., before a portion of the handle portion 302 is attached). An example of operation 420 is illustrated in FIG. 5A , in which a PIT tag 316 is loaded through the cannula tip 306. The PIT tag 316 may be loaded such that a distance exists between the PIT tag 316 and the drive element 312. After operation 420, in operation 430, an anti-migration device 318 is loaded into the cannula 304, for example, through the cannula tip 306. An example of operation 430 is illustrated in FIG. 5C . The anti-migration device 318 may be loaded such that a distance exists between the anti-migration device 318 and the PIT tag 316. After operation 430, the deployment system 300 is in a ready-to-deploy state as illustrated in FIG. 5C . It can be seen that the ready-to-deploy state illustrated in FIG. 5C corresponds to the inset of FIG. 3B .

[0072] The deployment system 300 may exist in a ready-to-deploy state for an extended period of time (e.g., several years) before the deployment packages 314 are to be used. At such time, the deployment system 300 may be operated to simultaneously (or nearly simultaneously) deploy the entire deployment package 314. FIGS. 6A-6B illustrate a deployment procedure for the deployment system 300. Initially, as shown in FIG. 6A, the deployment system 300 is provided in a ready-to-deploy state. This state also corresponds to the state shown in FIGS. 3B and 5C. Subsequently, the operator (e.g., a surgeon) actuates the deployment button 308, causing the drive element 312 to move from the preloaded position to the deployed position. In this position, the drive element 312 is extended to a point near the cannula tip 306, as shown in FIG. 6B. The contact force of the actuation element 312 against the PIT tag 316, and therefore against the anti-migration device 318, causes the deployed package 314 to exit the cannula 304 as a sheathed PIT tag, with the PIT tag 316 within the anti-migration device 318, and the anti-migration device 318 returning to its flared shape. For illustrative purposes, the deployed anti-migration device 318 is shown as having a longer length than the PIT tag 316, although in practical implementations, the anti-migration device 318 may preferably be of shorter or equal length such that the anti-migration device 318 does not extend beyond the PIT tag 316 in either direction.

[0073] 6A-6B illustrate a deployment procedure in which the cannula tip 306 generally remains stationary relative to the deployment area while the drive element 312 and deployment package 314 move into the deployment area, although in some implementations the reverse may be true. In such implementations, the cannula 304 with the deployment package 314 may be advanced to the deployment site, after which the cannula 304 may be withdrawn (e.g., along a guidewire or drive element 312). Once the cannula 304 is retracted sufficiently that the cannula tip 306 has cleared the deployment package 314, the deployment package 314 will have been deployed into the deployment area. The cannula 304 may then be fully withdrawn. Retraction of the cannula tip 306 may be initiated automatically in response to actuation of the deployment button 308, or the operator may manually retract the cannula tip 306. Such a procedure may be beneficial when hard tissue (e.g., a tumor) is located in the deployment area, as it may reduce lateral migration that would otherwise be caused by the force of the deployment package 314 against the hard tissue. In such cases, the cannula tip 306 itself may be used to first pierce the hard tissue, thereby creating a reliable deposition site for the deployment package 314.

[0074] Generally, the PIT tag 316 may enter the anti-migration device 318 in one of two ways, depending on the relative physical parameters (e.g., relative diameters) of the cannula 304, the PIT tag 316, and the anti-migration device 318, and, in some cases, the relative stiffness of the tissue into which the deployment package 314 is deployed. In the first case, the force of the drive element 312 pushes the PIT tag 316 into the compressed anti-migration device 318 within the cannula 304, such that the anti-migration device 318 securely holds the PIT tag 316. The force of the drive element 312 may then continue to push both the PIT tag 316 and the anti-migration device 318 simultaneously into the tissue. In the second case, the force of the drive element 312 causes the PIT tag 316 itself to exert a force on the anti-migration device 318, causing the anti-migration device 318 to enter the tissue and expand. The drive element 312 continues to exert a force on the PIT tag 316 so that the PIT tag 316 enters the anti-migration device 318 within the tissue and becomes securely held by the anti-migration device 318. In such an implementation, the inner diameter of a portion of the anti-migration device 318 (e.g., the inner diameter of the small diameter portion 202c, 202e, or 202f shown in FIGS. 2C, 2E, and 2F) can be smaller than the outer diameter of the PIT tag 316. Movement of the PIT tag 316 causes the small diameter portion of the anti-migration device 318 to expand, and the spring force of the anti-migration device 318 holds the PIT tag 316 firmly in place.

[0075] In any of the above procedures, the deployment procedure may be guided through the use of imaging technology. For example, an operator may monitor the implantation area to ensure that the PIT tag 316 and anti-migration device 318 are properly positioned relative to each other and relative to the implantation area itself. Thus, the operator can ensure that the combined deployment package 314, upon deployment, is properly seated relative to the lesion, tumor, or other object whose location the PIT tag 316 is intended to mark.

[0076] In either the preloading or deployment procedures, the deployment package 314 or PIT tag 316 and anti-migration device 318 may be packaged with a lubricant to facilitate movement of the package 314 or PIT tag 316 and anti-migration device 318 relative to the cannula 304. Such a lubricant may include a biocompatible silicone-based lubricant.

[0077] 7A-7B illustrate a second exemplary implantation system 700 according to the present disclosure in a ready-to-deploy state. Compared to the first implantation system 300 shown in FIGS. 3A-3B, the second implantation system 700 may facilitate attachment between the tag and the anti-migration device during the implantation procedure due to the use of a multi-part sheath structure.

[0078] The implantation system 700 includes a handle portion 702 and a cannula 704 in which a deployment package 714 is disposed. The handle portion 702 includes a deployment button 708 that activates a plunger 710, which in turn activates a drive element 712. The handle portion 702 and one or more of its components may be manufactured from a suitable plastic. The deployment button 708 is connected to a housing of the handle portion 702 and is actuatable by a user, such as a surgeon. The deployment button 708 may be physically depressed or slid, or it may be a soft button configured to generate an electrical or electronic signal when activated. The cannula 704 extends a distance away from the handle portion 702 and terminates in a cannula tip 706. The cannula 704 may be formed from a suitable metal. The cannula 704 has a length that may range from 25 mm (1 inch) to 200 mm (8 inches), and in an exemplary embodiment, may range from 50 mm (2 inches) to 150 mm (6 inches). The length of the cannula 704 affects the extent of the implantation system 700's accessibility to tissue sites within a subject's body. A cannula 704 of a longer length may be used when adjustment assistance (e.g., for stereotactic techniques) is used. The cannula 704 terminates in a cannula tip 706. The inner diameter of the cannula 704 may closely match the outer diameter of the deployment package 714, which may be approximately 0.15 mm (0.006 inches). For purposes of explanation, the direction of the cannula tip 706 is referred to herein as the "distal" direction, and the direction of the handle portion 702 is referred to herein as the "proximal" direction.

[0079] A drive element 712 extends through the cannula 704. When the deployment button 708 is actuated, the plunger 710 operates to move the drive element 712 axially within the cannula 704. The drive element 712 may be formed from wire or a sufficiently stable plastic fiber. As a result, the drive element 712 may be moved along a linear, guided slide path between a preloaded position and a deployed position. In the deployed position, force from the plunger 710 is transmitted to a preloaded deployment package 714 at a location near the cannula tip 706. Thus, when the deployment button 708 is actuated, the deployment package 714 may be driven out of the cannula 704 by the axial movement of the drive element 712 to a tissue site at the location of the cannula tip 706. This may be achieved by having drive element 712 coaxially aligned with cannula 704, thus pushing pre-loaded deployment package 714 past cannula tip 706 and out of cannula 704. An example of deployment package 714 is shown in more detail in inset B, which corresponds to FIG.

[0080] In FIG. 7B , the drive element 712 is in a preloaded position. The deployment package 714 includes a PIT tag 716 distal to the drive element 712 and an anti-migration device divided into a first anti-migration device portion 718 distal to the drive element 712 and proximal to the cannula tip 706 and a second anti-migration device portion 720 distal to the drive element 712 and proximal to the PIT tag 716. The PIT tag 716 may be, for example, the PIT tag 100 illustrated in FIG. 1 . As an alternative to the configuration shown in FIG. 7B , the deployment package 714 of FIG. 7A may be formed with the PIT tag 716 already disposed within the anti-migration device 718, as described in more detail below with respect to FIGS. 11A-11B . However, by comparison, the configuration shown in FIG. 7B may enable the use of a cannula having a smaller diameter. The anti-migration device may have the same overall form factor as, for example, any of the anti-migration devices 200a-200h illustrated in Figures 2A-2H, or modifications or alternatives thereto as described above, except that the anti-migration device of Figure 7B is split into two sections. The first and second anti-migration devices 718, 720 are in their compressed states. Due to their prestress, the first and second anti-migration devices 718, 720 (and thus the PIT tag 716) maintain their position within the cannula 304.

[0081] FIG. 8 illustrates an exemplary process flow for preloading a deployment package 714 into a deployment system 700. For purposes of explanation, the process flow will be described in the context of the deployment system 700 illustrated in FIG. 7. In this illustration, various processes within the process flow are illustrated in FIGS. 9A-9D. In operation 810, the process flow includes placing a drive element 712 in a preloaded position. Operation 810 may include activating a button, such as the deployment button 708 or a reset / back button (not shown). If the drive element 712 is already in the preloaded position, operation 810 may be omitted. Then, in operation 820, a second anti-migration device portion 720 (which would be located proximal to the drive element 712) is loaded into the cannula 704, for example, via the cannula tip 706. An example of operation 820 is illustrated in FIG. 9A. The second anti-migration device portion 720 can be loaded such that a distance exists between the second anti-migration device portion 720 and the drive element 712. If the proximal end of the cannula 304 is accessible (e.g., before a portion of the handle portion 302 is attached), one or more of the PIT tag 716, the first anti-migration device portion 718, and / or the second anti-migration device portion 720 can be loaded via the proximal end.

[0082] Next, in operation 830, the PIT tag 716 is loaded into the cannula 704, for example, via the cannula tip 706. An example of operation 830 is illustrated in FIG. 9B. The PIT tag 716 can be loaded such that a distance exists between the PIT tag 716 and the second anti-migration device portion 720. After operation 830, in operation 840, the first anti-migration device portion 718 (which will be located proximal to the cannula tip 706) is loaded into the cannula 704, for example, via the cannula tip 706. An example of operation 840 is illustrated in FIG. 9C. The first anti-migration device portion 718 can be loaded such that a distance exists between the first anti-migration device portion 718 and the PIT tag 716. After operation 840, the deployment system 700 is in a ready-to-deploy state, as illustrated in FIG. 9D. It can be seen that the ready-to-deploy state illustrated in FIG. 9D corresponds to the inset of FIG. 7B.

[0083] The deployment system 700 may exist in a ready-to-deploy state for an extended period of time (e.g., several years) before the deployment packages 714 are to be used. At such time, the deployment system 700 may be operated to simultaneously (or nearly simultaneously) deploy the entire deployment package 714. FIGS. 10A-10B illustrate a deployment procedure for the deployment system 700. Initially, as shown in FIG. 10A, the deployment system 700 is provided in a ready-to-deploy state. This state also corresponds to the state shown in FIGS. 7B and 9D. Subsequently, an operator (e.g., a surgeon) actuates the deployment button 708, causing the drive element 712 to move from the preloaded position to the deployed position. In this position, the drive element 712 is extended to a point near the cannula tip 706, as shown in FIG. 10B. The contact force of the actuation element 712 against the second anti-migration device portion 720, and thus against the PIT tag 716, and thus against the first anti-migration device portion 718, causes the deployed package 714 to exit the cannula 704 as a sheathed PIT tag, the PIT tag 716 within the first and second anti-migration device portions 718, 720, and the entire anti-migration device returning to its flared shape. For illustrative purposes, the deployed anti-migration device is shown as having a length longer than the PIT tag 716, although in practical implementations, the combined length of the first and second anti-migration device portions 718, 720 can preferably be shorter or equal to the PIT tag 716, such that the combined length does not extend beyond the PIT tag 716 in either direction.

[0084] 10A-10B illustrate a deployment procedure in which the cannula tip 706 generally remains stationary relative to the deployment area while the drive element 712 and deployment package 714 move into the deployment area, although in some implementations the reverse may be true. In such implementations, the cannula 704 with the deployment package 714 may be advanced to the deployment site, and the cannula 704 may then be withdrawn (e.g., along a guidewire or drive element 712). Once the cannula 704 has been retracted sufficiently that the cannula tip 706 has cleared the deployment package 714, the deployment package 714 will have been deployed into the deployment area. The cannula 704 may then be fully withdrawn. Retraction of the cannula tip 706 may be initiated automatically in response to actuation of the deployment button 708, or the operator may manually retract the cannula tip 706. Such a procedure may be beneficial when hard tissue (e.g., a tumor) is located in the deployment area, as it may reduce lateral migration that would otherwise be caused by the force of the deployment package 714 against the hard tissue. In such cases, the cannula tip 706 itself may be used to first puncture the hard tissue, thereby creating a reliable deposition site for the deployment package 714.

[0085] Generally, the PIT tag 716 may enter the first and second anti-migration device portions 718, 720 in one of two ways, depending on the relative physical parameters (e.g., relative diameters) of the cannula 704, the PIT tag 716, and the first and second anti-migration device portions 718, 720, and, in some cases, the relative stiffness of the tissue into which the deployment package 314 is deployed. In the first case, the force of the drive element 712 pushes the compressed second anti-migration device portion 720 against the PIT tag 716, pushing the PIT tag 716 into the compressed first anti-migration device portion 718 within the cannula 704, thereby ensuring that the anti-migration device holds the PIT tag 716 securely. The force of the drive element 712 may then continue to push both the PIT tag 716 and the first and second anti-migration device portions 718, 720 simultaneously into the tissue. In the second case, the force of the drive element 712 causes the second anti-migration device portion 720 itself to exert a force on the PIT tag 716 and on the first anti-migration device portion 718, causing the first anti-migration device portion 718 to enter and expand into the tissue. The drive element 712 continues to exert a force on the second anti-migration device portion 720, driving the PIT tag 716 out of the cannula 704 and into the partially expanded first anti-migration device portion 718, and finally driving the second anti-migration device portion 720 out of the cannula and beyond the exposed portion of the PIT tag 716. Thus, the PIT tag 716 becomes encapsulated and securely held by the anti-migration device within the tissue.

[0086] In any of the above procedures, the deployment procedure may be guided through the use of imaging techniques, such as, for example, ultrasound, X-ray, and / or MRI imaging modalities. For example, an operator may monitor the implantation area to ensure that the PIT tag 716 and the first and second anti-migration portions 718, 720 are properly positioned relative to each other and relative to the implantation area itself. Thus, the operator can ensure that the combined deployment package 714, upon deployment, is properly seated relative to the lesion, tumor, or other object whose location the PIT tag 716 is intended to mark.

[0087] While the deployment package 314, 714 is illustrated in FIGS. 3A-3B and 7A-7B as consisting of several components axially displaced from one another, in alternative implementations, the PIT tag and anti-migration device may be assembled before loading into the deployment apparatus. In such implementations, the anti-migration device may be secured to the PIT tag by spring force, overmolding, shrink tubing, glue bonding, friction fit, form-fitting, solvent bonding, or the like. An example of such an implementation is illustrated in FIGS. 11A-11B. If the implantable shell of the PIT tag is a two-part structure (e.g., as illustrated in FIG. 1), the anti-migration device may be secured by partially inserting the anti-migration device between the two parts. Utilizing the deployment method illustrated in FIGS. 3A-3B or 7A-7B may reduce the likelihood of deployment jams, in which the deployment package fails to properly exit the cannula. Additionally, the deployment methods illustrated in Figures 3A-3B or 7A-7B may allow for the use of cannulas with reduced diameters, for example, because the deployment package itself may have a reduced diameter. In comparison, the deployment system illustrated in Figures 11A-11B may allow for a wider range of usable designs for the anti-migration device.

[0088] 11A-11B illustrate a third exemplary implantation system 1100 according to the present disclosure in a ready-to-deploy state. The implantation system 1100 includes a handle portion 1102 and a cannula 1104 in which a deployment package 1114 is disposed.

[0089] The handle portion 1102 includes a deployment button 1108 or other actuator that operates the plunger 1110, which in turn operates the drive element 1112. The handle portion 1102 and one or more of its components may be manufactured from a suitable plastic. The deployment button 1108 is connected to the housing of the handle portion 1102 and is actuatable by a user, such as a surgeon. The deployment button 1108 may be physically depressed or moved, or it may be a soft button configured to generate an electrical or electronic signal when activated. The cannula 1104 extends a distance away from the handle portion 1102 and terminates in a cannula tip 1106. The cannula 1104 may be formed from a suitable metal. The cannula 1104 may range from 25 mm (1 inch) to 200 mm (8 inches), and in some exemplary embodiments, has a length that is from 50 mm (2 inches) to 150 mm (6 inches). The length of the cannula 1104 affects the extent of the implantation system 1100's accessibility to tissue sites within a subject's body. A cannula 1104 of longer length may be used when adjustment assistance (e.g., for stereotactic techniques) is used. The cannula 1104 terminates in a cannula tip 1106. The inner diameter of the cannula 1104 may closely match the outer diameter of the deployment package 1114, which may be approximately 0.15 mm (0.006 inches). For purposes of explanation, the direction of the cannula tip 1106 is referred to herein as the "distal" direction, and the direction of the handle portion 1102 is referred to herein as the "proximal" direction.

[0090] The drive element 1112 extends through the cannula 1104. When the deployment button 1108 is actuated, the plunger 1110 operates to move the drive element 1112 axially within the cannula 1104. The drive element 1112 may be formed from wire or a sufficiently stable plastic fiber. As a result, the drive element 1112 may be moved along a linear, guided slide path between a preloaded position and a deployed position. In the deployed position, force from the plunger 1110 is transmitted to a preloaded deployment package 1114 at a location near the cannula tip 1106. Thus, when the deployment button 1108 is actuated, the deployment package 1114 may be driven out of the cannula 1104 by axial movement of the drive element 1112 to a tissue site at the location of the cannula tip 1106. This may be achieved by having the drive element 1112 coaxially aligned with the cannula 1104, thus pushing the pre-loaded deployment package 1114 past the cannula tip 1106 and out of the cannula 1104. An example of a deployment package 1114 is shown in more detail in inset B, which corresponds to FIG.

[0091] In FIG. 11B , the drive element 1112 is in a preloaded position. The deployment package 1114 is preassembled and includes a PIT tag 1116 surrounded by an anti-migration device 1118, both of which are distal to the drive element 1112 and proximal to the cannula tip 1106. While FIG. 11B illustrates the PIT tag 1116 as being completely encapsulated by the anti-migration device 1118, in some implementations, only a portion of the PIT tag 1116 (e.g., only a distal portion or only a proximal portion) may be so encapsulated. The PIT tag 1116 may be, for example, the PIT tag 100 illustrated in FIG. 1 . The anti-migration device 1118 may be, for example, any of the anti-migration devices 200a-200h illustrated in FIGS. 2A-2H or modifications or alternatives thereto as described above. The anti-migration device 1118 is in a compressed state. Due to the pre-stress, the anti-migration device 1118 (and therefore the PIT tag 1116 ) maintains its position within the cannula 1104 .

[0092] Compared with the process for preloading the deployment packages 314, 714 of FIGS. 3A-3B and 7A-7B, described above with respect to FIGS. 4 and 8, the process flow for preloading the deployment package 1114 of FIG. 11B may be relatively simplified. For example, the drive element 1112 may be installed at the preloading position, followed by loading the preassembled deployment package 1114 including the PIT tag 1116 and anti-migration device 1118 either through the cannula tip 1106 or, if the proximal end of the cannula 1104 is accessible, through the proximal end. After loading the preassembled deployment package 1114, the deployment system 1100 is in a ready-to-deploy state corresponding to the inset in FIG. 11B. The deployment system 1100 may remain in the ready-to-deploy state for an extended period of time (e.g., several years) before the deployment package 1114 is to be used. At such time, the deployment system 1100 may be operated to deploy the preassembled deployment package 1114. 12A-12B and 13A-13B illustrate the deployment procedure of the deployment system 1100 for two different examples of pre-assembled deployment packages 1114. FIG.

[0093] Initially, as shown in FIGS. 12A and 13A , the deployment system 1100 is provided in a ready-to-deploy state. In FIG. 12A , the PIT tag 1116 is substantially completely encapsulated within the anti-migration device 1118, which may be implemented as a cage-like or basket-like resilient device. However, in FIG. 13A , only a proximal portion of the PIT tag 1116 is encapsulated within the anti-migration device 1118, which may be implemented as a half-hourglass or trumpet-like resilient device. Subsequently, an operator (e.g., a surgeon) actuates the deployment button 1108, moving the drive element 1112 from the pre-loaded position to the deployed position. In this position, the drive element 1112 is extended to a point near the cannula tip 1106, as shown in FIGS. 12B and 13B . The contact force of the drive element 1112 against the deployment package 1114 causes the deployment package 1114 to exit the cannula 1104. As shown in FIG. 12B , after deployment, the anti-migration device 1118 securely holds the PIT tag 1116 therein, approximately at its center (axially), while the outer portion of the anti-migration device 1118 expands radially outward to resist subsequent migration of the PIT tag 1116. As shown in FIG. 13B , after deployment, the distal portion of the anti-migration device 1118 securely holds the proximal portion of the PIT tag 1116, while the proximal portion of the anti-migration device 1118 expands radially outward such that the anti-migration device 1118 has a flared or trumpet-like shape. Thus, the anti-migration device 1118 can resist subsequent migration of the PIT tag 1116, particularly migration along the channel created by the cannula 1104 after the cannula 1104 is removed. Although FIG. 13B illustrates the anti-migration device 1118 engaged with a proximal portion of the PIT tag 1116, in other implementations, the proximal portion of the anti-migration device 1118 can instead be engaged with a distal portion of the PIT tag 1116, and the distal portion of the anti-migration device 1118 can expand radially outward with a flared or trumpet-like shape.

[0094] FIGS. 14A-14L and 14O-14T each illustrate an example of a deployed package. For ease of illustration and explanation, the deployed package is a one-piece anti-migration device structure and is therefore deployed by the deployment system 300 illustrated in FIGS. 3A-3B. However, the package may have a similar appearance even when a two-part structure is used for the anti-migration device structure. To further illustrate the wide range of potential designs for the anti-migration device, the specific designs shown in FIGS. 14A-14L and 14O-14T are not selected from those specifically illustrated in FIGS. 2A-2J, but rather are further examples of the modified sheath described above. Additionally, FIGS. 14E-14L illustrate an example in which the anti-migration device is used simultaneously with a cap-like inner anti-migration device, such as the anti-migration device 200h illustrated in FIG. 2H. However, the example illustrated in FIGS. 14E-14L may be used without the cap-like inner anti-migration device. Additionally, in each of Figures 14E-14L and 14O-14T, the anti-migration device may be formed from at least one nitinol wire wrapped around the PIT tag.

[0095] In particular, Figure 14A illustrates an expanded form of a PIT tag 1410a encapsulated within an anti-migration device 1420a having a generally flower-like structure in the axial direction, including multiple petal-like flanged portions (which may be considered a type of protrusion according to the present disclosure) flared at its extreme axial ends, with a central portion for retaining the PIT tag 1410a. Figure 14B illustrates an expanded form of a PIT tag 1410b encapsulated within an anti-migration device 1420b that is similarly flower-like but formed from a thicker material. Figure 14C illustrates a compressed form of a PIT tag 1410c almost completely enclosed within a helical anti-migration device 1420c. Grooves between adjacent portions of the helix can provide small diameter regions; however, in other implementations, grooves can extend throughout the entire anti-migration device 1420c such that gaps exist between adjacent portions of the helix. In the expanded configuration, the diameter of the anti-migration device 1420c can be, for example, 2 to 5 times larger than in the compressed configuration. As described above, in such implementations, it may be preferable to form the anti-migration device 1420c from a material that is substantially transparent to RF radiation. FIG. 14D illustrates the expanded configuration of a PIT tag 1410d contained within a thin, spiral-shaped anti-migration device 1420d that includes protruding ends. In such implementations, the protruding ends can be formed in any shape that provides anti-migration properties to the deployed package.

[0096] As described above, anti-migration devices according to the present disclosure need not exhibit rotational symmetry. Additionally, if an anti-migration device includes a flared or protruding portion, the portion need not be located at the end of the anti-migration device. For example, FIG. 14E illustrates the expanded configuration of a PIT tag 1410e encapsulated within an anti-migration device 1420e, which has a generally helical or coil-shaped main portion with two radially outwardly protruding portions (increased coil diameter) axially displaced away from the end of the anti-migration device 1420e and toward the central portion of the anti-migration device 1420e. In the compressed configuration, the wires may not overlap to prevent the need for a larger cannula diameter. While FIG. 14E illustrates two protruding portions, both of which protrude in the same radial direction, in other examples, the anti-migration device may include one protruding portion or three or more protruding portions, and the protruding portions may protrude in different radial directions. In some implementations, the protruding portion may be capable of twisting in one or more directions (eg, tangential and / or axial directions of the PIT tag 1410e).

[0097] 14F, a PIT tag 1410f is encapsulated within an anti-migration device 1420f, which is shown in an expanded configuration having a generally spiral or coil-shaped main portion with two sets of radially protruding portions (one set at each end of the anti-migration device 1420f). As described above, any number of radially protruding portions, sets of radially protruding portions, or various other combinations of radially protruding portions (e.g., one protruding portion or three or more protruding portions) can be present at a given end, and the number of radially protruding portions at one end of the sheath can be different from the number of radially protruding portions at the opposite end of the sheath. In some implementations, only one end can have any radially protruding portions. One such example is illustrated in the expanded configuration shown in FIG. 14G, where a PIT tag 1410g is encapsulated within an anti-migration device 1420g having a generally helical or coil-shaped main portion with two radially protruding portions at only one end of the anti-migration device 1420g. In any implementation, the radially protruding portions may be capable of twisting in one or more directions. In FIG. 14G, an example of a position into which the radially protruding portions may twist is illustrated in dashed lines, where the radially protruding portions rotate between an axially forward direction and an axially backward direction of the sheath.

[0098] 14O-14T, PIT tags 1410o, 1410q, 1410s are encapsulated within anti-migration devices 1420o, 1420q, 1420s, which have a generally spiral or coil-shaped, radially extending, protruding main portion (i.e., forming the anti-migration portion of the device 1420o, 1420q, 1420s), with two spiral or coil-shaped, radially fixed end portions that tightly grip the rounded ends of the PIT tags 1410o, 1410q, 1410s. As discussed above, the anti-migration devices 1420o, 1420q, 1420s can be formed from one or more wires (e.g., one or more wires formed from a shape memory material, such as nitinol). For example, Figures 14O and 14P illustrate an anti-migration device 1420o formed from two nitinol wires. Figures 14Q and 14R illustrate an anti-migration device 1420q formed from three nitinol wires. And Figures 14S and 14T illustrate an anti-migration device 1420s formed from four nitinol wires. As shown in Figures 14O-14T, in the expanded configuration, the anti-migration devices 1420o, 1420q, 1420s have a generally flower-like structure in the axial direction, including a main portion with multiple petal-like flanged portions that are radially flared (i.e., when viewed axially, extend in different radial directions from the marker body and may be considered a type of protrusion according to the present disclosure), with fixed end portions that retain the rounded ends of the PIT tags 1410o, 1410q, 1410s. However, anti-migration devices according to the present disclosure may be formed from a variety of materials and employ any number of wires spiraled around the PIT tag in a variety of configurations, as will be understood by one of ordinary skill in the art.

[0099] In another example, an anti-migration device according to the present disclosure may be implemented as a cage-type matrix that completely surrounds the PIT tag, thereby defining an interior in which the PIT tag is disposed. In FIG. 14H , the PIT tag 1410h is completely enclosed within the cage-type anti-migration device 1420h. The cage-type anti-migration device 1420h may be attached to the PIT tag 1420h by, for example, one or more wires, anchors, or coils, thereby reducing or preventing movement of the PIT tag 1410h within the cage-type anti-migration device 1420h. The cage-type anti-migration device 1420h expands upon deployment and moves away from the PIT tag 1410h, defining an area in which the PIT tag 1410h is contained due to the establishment of the cage within the tissue, and the PIT tag 1410h may move freely within the area defined by the cage-type anti-migration device 1420h. In any implementation, the cage-type anti-migration device 1420h may be anchored by a cage-type structure, or the sheath 1420h may include additional structure that acts as an anchor, such as the radially extending protruding portions described with respect to other examples herein. When using a cage-type anti-migration device 1420h, materials may be selected such that the sheath does not act as a Faraday cage, but instead allows RF and / or other low frequency electromagnetic radiation to pass through the sheath to the PIT tag 1410h.

[0100] An anti-migration device according to the present disclosure does not necessarily completely surround the PIT tag in the circumferential direction, but instead may be comprised of multiple separate sections in the circumferential direction. In such implementations, the anti-migration device may be attached (e.g., by welding) to the PIT tag prior to insertion into the deployment system. FIGS. 14I and 14J illustrate two such example expanded configurations. In FIG. 14I, a PIT tag 1410i is attached to four anti-migration flaps 1420i that collectively form the anti-migration device, although only three of the anti-migration flaps 1420i are visible in the side view of FIG. 14I. The anti-migration flaps 1420i may instead be wire sections (i.e., may have a narrower width than that illustrated in FIG. 14L) and may be formed from any one or more of the materials described above. Each anti-migration flap 1420i is curved away from the PIT tag 1410i at its end in the expanded configuration so that the anti-migration flap 1420i cuts into tissue when the PIT tag 1410j is deployed. In FIG. 14J, the PIT tag 1410j is attached to two anti-migration flaps 1420j that collectively form an anti-migration device. In contrast to the welded or glued configuration shown in FIG. 14I, the anti-migration flap 1420j in FIG. 14J is inserted between two parts that make up the shell of the PIT tag 1410j. In practical implementations of the example shown in FIGS. 14I and 14J, any number of flaps can be used. The flaps can be formed, for example, from nitinol having a thickness of 0.05 mm (0.002 inches) to 0.2 mm (0.08 inches).

[0101] In addition to or instead of the protrusions, flaps, or wires described above, anti-migration devices according to the present disclosure may include other types of anti-migration features. In FIG. 14K, a PIT tag 1410k is partially encapsulated within a torsion coil anti-migration device 1420k shown in an expanded configuration. The torsion coil anti-migration device 1420k may be attached to the PIT tag 1410k near its center so that portions of the torsion coil anti-migration device 1420k near the ends of the PIT tag 1410k are free. Upon deployment, the free ends may expand within tissue to provide an outward radial force to anchor the PIT tag 1410k. In FIG. 14L, a PIT tag 1410l is partially encapsulated within an anti-migration device 1420l that terminates in a barbed or serrated cone. The barbs or serrations may resist movement of the PIT tag 1410l in the longitudinal direction. Such implementations may be used when a practitioner desires to anchor the PIT tag 1410l to a particular feature (e.g., a mass within tissue). Barbs and / or serrations may also be combined with protruding portions, either as separate features or as combined features (e.g., a fishhook-like portion).

[0102] Anti-migration devices according to the present disclosure may also include one or more features for receiving force from the drive element and thereby assisting the deployment process. In implementations in which anchor-type anti-migration features are used (such as that shown in FIG. 14L), pointed features may improve the ability of the anti-migration device to cut into harder tissue (e.g., tumor tissue) while reducing lateral movement during implantation. One such example is illustrated in FIG. 14M, which shows two perspective views of a PIT tag 1410m encapsulated within an anti-migration device 1420m. At the distal end of the anti-migration device 1420m, a spade-shaped anti-migration feature is provided. This anti-migration feature may assist in cutting into tissue. At the proximal end of the anti-migration device 1420m, a seat feature is provided that curves partially around the proximal end of the PIT tag 1410m. The seat feature receives force directly from the drive element and therefore may be used to increase the force with which the anti-migration device 1420m may enter tissue (e.g., by increasing the force applied by the spade-shaped anti-migration feature). Seat features such as those shown in Figures 14M and 14N may be used with any of the anti-migration devices illustrated and / or described above, and are not limited to use with anti-migration devices having spade-type anti-migration features.

[0103] Illustrative examples of marking systems, deployment systems, methods for marking target locations, and localization marker devices are provided below. Embodiments of the systems, methods, and devices described herein may include any one or more of the below-described notes, and any combination thereof.

[0104] Appendix 1. A marking system for implantation into tissue, the system comprising: a marker body having an outer surface, the marker body including a transponder configured to respond to electromagnetic radiation from an external source, and a microchip operatively connected to the transponder and configured to activate in response to the electromagnetic radiation; and an anti-migration device configured to receive at least a portion of the marker body, engage tissue into which the marker body is to be implanted, and resist migration of the marker body after implantation.

[0105] Clause 2. The system of Clause 1, wherein the anti-migration device includes a portion configured to transition between a compressed state and an expanded state.

[0106] Clause 3. The system of Clause 2, wherein the anti-migration device has a first size and a first shape in a compressed state, and wherein the anti-migration device has a second size and / or a second shape in an expanded state, wherein one or both of the second size and second shape are different from the first size and first shape, respectively.

[0107] Clause 4. The system of Clause 3, wherein a portion of the anti-migration device is configured to expand from a first size to a second size during implantation of the marking system.

[0108] Clause 5. The system of Clause 4, wherein the portion of the anti-migration device configured to expand from the first size to the second size is an end portion of the anti-migration device.

[0109] Clause 6. The system of Clause 4 or Clause 5, wherein the portion of the anti-migration device configured to expand from the first size to the second size includes first and second end portions of the anti-migration device.

[0110] Clause 7. The system of any one of clauses 4-6, wherein the portion of the anti-migration device configured to expand from the first size to the second size is formed from a braided, woven, mesh, or web-like structure.

[0111] Clause 8. The system of Clause 4, wherein the portion of the anti-migration device configured to expand from the first size to the second size is located in a central portion of the anti-migration device.

[0112] Clause 9. The system of Clause 8, wherein the portion of the anti-migration device configured to expand from a first size to a second size is formed from a braided, woven, mesh, or web-like structure.

[0113] Clause 10. The system of any one of clauses 3-9, wherein a portion of the anti-migration device is configured to change from a first shape to a second shape during implantation of the marking system.

[0114] Clause 11. The system of clause 10, wherein the portion of the anti-migration device configured to change shape includes at least one protrusion.

[0115] Clause 12. The system of clause 10 or clause 11, wherein the portion of the anti-migration device configured to change shape includes a plurality of protrusions.

[0116] Appendix 13. The system of Appendix 11 or Appendix 12, wherein the at least one protrusion is configured to move from an axially extending position to a radially extending position during implantation of the marking system.

[0117] Addendum 14. The system of any one of Addendums 11-13, wherein at least one protrusion includes a point configured to engage tissue into which the body is implanted and resist movement of the marking system.

[0118] Addendum 15. The system of any one of Addendums 1-14, wherein the anti-migration device includes a hollow structure configured to receive a portion of the marker body, and an end of the hollow structure includes a pointed point configured to penetrate hard or bony tissue.

[0119] Clause 16. The system of any one of clauses 1-15, wherein the anti-migration device is formed at least in part from a shape-memory material.

[0120] Clause 17. The system of clause 16, wherein the shape memory material is at least one of silicone, ethylene propylene diene monomer, thermoplastic elastomer, polyether ether ketone, polypropylene, or a combination thereof.

[0121] Clause 18. The system of clause 16, wherein the material is nitinol.

[0122] Clause 19. The system of any one of clauses 1-18, wherein the anti-migration device comprises a sheath configured to receive at least a portion of the marker body.

[0123] Clause 20. The system of clause 19, wherein the sheath has a unitary construction.

[0124] Clause 21. The system of clause 19, wherein the sheath includes a first sheath portion and a second sheath portion.

[0125] Addendum 22. The system of any one of Addendums 19-21, wherein the sheath is formed from a braided, woven, mesh, or web-like structure.

[0126] Clause 23. The system of clause 22, wherein the braided, woven, mesh, or web-like structure has an hourglass shape.

[0127] Addendum 24. The system of Addendum 22 or Addendum 23, wherein the braided, woven, mesh, or web-like structure defines an interior in which the marker body is disposed.

[0128] Addendum 25. A system described in any one of Addendums 22-24, wherein the braided, woven, mesh, or web-like structure is configured to engage a distal portion of the marker body or a proximal portion of the marker body.

[0129] Addendum 26. A system described in any one of Addendums 19-25, wherein at least a portion of the sheath is configured to expand radially away from the outer surface of the marker body during implantation.

[0130] Clause 27. The system of Clause 1, wherein the anti-migration device includes a portion configured to transition between a tensioned state and an expanded state.

[0131] Addendum 28. The system of Addendum 1, wherein the anti-migration device is formed from one or more wires forming a helical body having a radially expanded and protruding main portion and two radially fixed end portions, the radially fixed end portions of the helical body being configured to firmly grip the marker body.

[0132] Clause 29. A deployment system comprising: a deployment device including: a handle portion including an actuator configured to cause a deployment action; and a cannula, the cannula attached to the handle portion at a first end of the cannula and terminating in a cannula end at a second end of the cannula opposite the first end; and a marking system disposed within a lumen of the cannula, the marking system including: a marker body having an outer surface, the marker body including a transponder configured to respond to electromagnetic radiation from an external source and a microchip operatively connected to the transponder and configured to activate in response to the electromagnetic radiation; and an anti-migration device configured to receive at least a portion of the marker body, the anti-migration device configured to resist migration of the marker body after implantation of the marking system into tissue.

[0133] Clause 30. The deployment system of clause 29, wherein the marker body is at least partially disposed within the anti-migration device while disposed within the lumen of the cannula.

[0134] Clause 31. The deployment system of clause 29, wherein the anti-migration device is axially displaced from the marker body within the lumen of the cannula.

[0135] Clause 32. The deployment system of clause 29, wherein a first portion of the anti-migration device is axially displaced within the lumen of the cannula from the marker body in a first direction, and a second portion of the anti-migration device is axially displaced within the lumen of the cannula from the marker body in a second direction opposite the first direction.

[0136] Clause 33. The deployment system of any one of clauses 29-32, wherein the deployment device further comprises a lubricant configured to facilitate relative movement between the marking system and the lumen of the cannula.

[0137] Appendix 34. A method of marking a target location within a patient's body, the method comprising: positioning a distal end of a cannula adjacent the target and below a tissue surface, wherein a tissue marker and an anti-migration device are disposed within a lumen of the cannula; deploying the tissue marker and anti-migration device at the target location; and expanding a portion of the anti-migration device to engage tissue at the target location to anchor the tissue marker at the target location.

[0138] Clause 35. The method of clause 34, wherein expanding a portion of the anti-migration device to engage tissue at the target location comprises releasing at least one wire portion of the anti-migration device from a compressed state and engaging tissue at the target location with the at least one wire portion of the anti-migration device.

[0139] Clause 36. The method of clause 34, wherein expanding a portion of the anti-migration device to engage tissue at the target location comprises radially expanding a sheath portion of the anti-migration device from a compressed state and engaging tissue at the target location with the radially expanded sheath portion of the anti-migration device.

[0140] Clause 37. The method of any one of clauses 34-36, further comprising positioning at least a portion of a tissue marker within an interior portion of the anti-migration device.

[0141] Clause 38. The method of clause 37, wherein positioning at least a portion of the tissue marker within the interior portion of the anti-migration device occurs after expanding the portion of the anti-migration device to engage tissue at the target location.

[0142] Clause 39. The method of clause 37, wherein positioning at least a portion of the tissue marker within an interior portion of the anti-migration device occurs prior to expanding a portion of the anti-migration device to engage tissue at the target location.

[0143] Clause 40. The method of any one of clauses 34-39, wherein the anti-migration device is in a compressed state when positioned within the lumen of the cannula.

[0144] Clause 41. The method of any one of clauses 34-40, further comprising pre-assembling the tissue marker and anti-migration device into the deployment package prior to positioning the distal end of the cannula.

[0145] Clause 42. The method of clause 41, wherein pre-assembling the tissue marker and anti-migration device into the deployment package includes attaching the anti-migration device to the tissue marker by at least one of spring force, an overmolding process, a shrink tubing process, glue bonding, friction fit, form-fitting, or a solvent bonding process.

[0146] Clause 43. The method of any one of clauses 34-40, wherein deploying the tissue marker and anti-migration device comprises deploying the anti-migration device at the target location, followed by deploying the tissue marker at the target location.

[0147] Clause 44. The method of any one of clauses 34-40 or 43, wherein deploying a tissue marker at the target location includes deploying an anti-migration device followed by positioning a portion of the tissue marker within the anti-migration device.

[0148] Clause 45. The method of clause 44, wherein positioning at least a portion of the tissue marker within the interior of the anti-migration device occurs prior to expanding a portion of the anti-migration device to engage tissue at the target location.

[0149] Clause 46. The method of clause 44, wherein positioning at least a portion of the tissue marker within the interior of the anti-migration device occurs after expanding a portion of the anti-migration device to engage tissue at the target location.

[0150] Clause 47. The method of any one of clauses 34-40, wherein deploying the tissue marker and anti-migration device includes deploying a first portion of the anti-migration device at the target location, deploying the tissue marker at the target location following the deployment of the first portion of the anti-migration device, and deploying a second portion of the anti-migration device at the target location following the deployment of the tissue marker.

[0151] Clause 48. The method of clause 47, wherein deploying the tissue marker at the target location includes positioning a portion of the tissue marker within an interior of a first portion of the anti-migration device.

[0152] Clause 49. The method of clause 47 or clause 48, wherein deploying the second portion of the anti-migration device at the target location includes positioning a portion of the tissue marker within the second portion of the anti-migration device.

[0153] Clause 50. The method of any one of clauses 47-49, wherein expanding a portion of the anti-migration device to engage tissue at the target location comprises expanding a first portion of the anti-migration device prior to deploying the tissue marker.

[0154] Clause 51. The method of any one of clauses 47-50, wherein expanding a portion of the anti-migration device to engage tissue at the target location further comprises expanding a second portion of the anti-migration device followed by deploying a tissue marker.

[0155] Addendum 52. The method of any one of Addendums 34-51, wherein the tissue marker is a passive integrated transponder (PIT) tag.

[0156] Clause 53. A localization marker device for implantation into tissue, comprising: an implantable marker having a body with an outer surface, the implantable marker being a transponder, a reflector, an active marker, a magnetic marker, a radioactive seed, a Doppler marker, a passive marker, a wireless tumor-localizing implant, or a combination thereof; and an anti-migration device configured to receive at least a portion of the marker body and at least partially engage the outer surface of the marker body, the anti-migration device including a portion configured to transition between a first state and a second state, wherein in the first state, the anti-migration device is configured to be disposed within a lumen of a cannula, and in the second state, the anti-migration device is configured to provide resistance to movement of the implantable marker after deployment from the cannula.

[0157] Clause 54. The device of clause 53, wherein the anti-migration device includes at least one surface feature configured to increase migration resistance.

[0158] Clause 55. The device of clause 53 or clause 54, wherein the anti-migration device includes a first anti-migration device portion and a second anti-migration device portion.

[0159] Clause 56. The device of clause 55, wherein the first anti-migration device portion is axially displaceable from the implantable marker in a first direction and the second anti-migration device portion is axially displaceable from the implantable marker in a second direction opposite the first direction.

[0160] Clause 57. The device of any one of clauses 53-56, wherein the anti-migration device has a mesh structure.

[0161] Addendum 58. The device of Addendum 57, wherein the mesh structure has an hourglass shape from a side view.

[0162] Addendum 59. The device of Addendum 57 or Addendum 58, wherein the mesh structure defines an interior in which an implantable marker is disposed.

[0163] Addendum 60. A device described in any one of Addendums 57-59, wherein the mesh structure is configured to engage one of the distal portion or the proximal portion of the implantable marker.

[0164] Addendum 61. A device described in any one of Addendums 57-60, wherein the mesh structure is a cage that surrounds the implantable marker.

[0165] Clause 62. The device of clause 53, wherein the anti-migration device comprises a nitinol wire with at least one barb.

[0166] Clause 63. The device of Clause 53, wherein the anti-migration device comprises a tube with a cutout portion, the cutout portion forming at least one barb.

[0167] Clause 64. The device of clause 53, wherein the anti-migration device includes a helical body formed from one or more wires.

[0168] Addendum 65. The device of Addendum 64, wherein when the anti-migration device is in a second state, the spiral body forms multiple flanged portions that extend in different radial directions from the marker body when viewed in an axial direction.

[0169] Clause 66. The device of clause 53, wherein in the first state, the anti-migration device is compressed and in the second state, the anti-migration device is expanded.

[0170] Clause 67. The device of clause 53, wherein in the first state, the anti-migration device is tensioned and in the second state, the anti-migration device is expanded.

[0171] The marking system described in any one of Notes 1-28 can be practiced with the location identification marker device described in any one of Notes 52-67 and / or in conjunction with the deployment system and / or method of marking a target location described in any one of Notes 29-33 and / or 34-52.

[0172] The deployment system described in any one of Notes 29-33 can be practiced with the marking system and / or localization marker device described in any one of Notes 1-28 and / or 53-67 and / or in conjunction with the method of marking a target location described in any one of Notes 34-52.

[0173] The method of marking a target location described in any one of Notes 34-52 can be practiced using a marking system described in any one of Notes 1-28, a deployment system described in any one of Notes 29-33, and / or a location-specific marker device described in any one of Notes 53-67.

[0174] The location marker device described in any one of Notes 53-67 can be used with the marking system described in any one of Notes 1-28, the deployment system described in any one of Notes 29-33, and / or the method of marking a target location described in any one of Notes 34-52.

[0175] The above description and associated figures teach the best modes of implementing the devices and methods of the present disclosure and are intended to be illustrative, not limiting. Many embodiments and applications other than the examples provided will be apparent to those skilled in the art upon perusal of the above description. The scope should be determined not with reference to the above description, but instead with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. It is anticipated and intended that future developments will occur in the art discussed herein, and that the disclosed systems and methods will be incorporated into future embodiments. In short, it should be understood that this application is capable of modification and variation.

[0176] Furthermore, the terminology of this description is not intended to limit the invention. For example, spatially relative terms such as "below," "lower," "lower side," "upper," "superior," "proximal," "distal," etc. may be used to describe the relationship of one element or feature to another element or feature as illustrated in the figures. These spatially relative terms are intended to encompass different positions (i.e., locations) and orientations (i.e., rotational orientations) of the device during use or operation in addition to the position and orientation shown in the figures. For example, if the device in the figures were inverted, elements described as "below" or "below" other elements or features would be "above" or "above" the other elements or features. Thus, the exemplary term "below" can encompass both upper and lower positions and orientations. The device may be oriented differently (rotated 90 degrees or at other orientations), and the spatially relative descriptors used herein may be interpreted accordingly.

[0177] All terms used in the claims are intended to be given their broadest reasonable interpretation and their ordinary meaning as understood by a person skilled in the art knowledgeable in the technology described herein, unless an express indication to the contrary is made herein. In particular, the use of singular articles such as "a," "the," "said," etc. should be read as reciting one or more of the indicated elements, unless the claim recites an express limitation to the contrary.

[0178] The Abstract is provided to allow the reader to quickly ascertain the nature of the technical disclosure. It should be considered with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Additionally, in the foregoing Detailed Description, various features may be found grouped together in various embodiments for the purpose of concisely simplifying the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Accordingly, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as separately claimed subject matter.

Claims

1. 1. A marking system for implantation in tissue, said system comprising: A marker body having an outer surface, the marker body comprising: a transponder configured to respond to electromagnetic radiation from an external source; a microchip operatively connected to said transponder and configured to operate in response to said electromagnetic radiation; a marker body including: an anti-migration device configured to receive at least a portion of the marker body, engage tissue into which the marker body is implanted, and resist migration of the marker body after implantation; A system comprising:

2. The system of claim 1 , wherein the anti-migration device includes a portion configured to transition between a compressed state and an expanded state.

3. 3. The system of claim 2, wherein the anti-migration device has a first size and a first shape in the compressed state, and the anti-migration device has a second size and / or a second shape in the expanded state, wherein one or both of the second size and the second shape are different from the first size and the first shape, respectively.

4. The system of claim 3 , wherein a portion of the anti-migration device is configured to expand from the first size to the second size during implantation of the marking system.

5. 5. The system of claim 4, wherein the portion of the anti-migration device configured to expand from the first size to the second size is an end portion of the anti-migration device.

6. 6. The system of claim 4 or claim 5, wherein the portion of the anti-migration device configured to expand from the first size to the second size includes first and second end portions of the anti-migration device.

7. 7. The system of claim 4, wherein the portion of the anti-migration device configured to expand from the first size to the second size is formed from a braided, woven, mesh, or web-like structure.

8. 5. The system of claim 4, wherein the portion of the anti-migration device configured to expand from the first size to the second size is located in a central portion of the anti-migration device.

9. 10. The system of claim 8, wherein the portion of the anti-migration device configured to expand from the first size to the second size is formed from a braided, woven, mesh, or web-like structure.

10. The system of any one of claims 3-9, wherein a portion of the anti-migration device is configured to change from the first shape to the second shape during implantation of the marking system.

11. The system of claim 10 , wherein the portion of the anti-migration device configured to change shape includes at least one protrusion.

12. 12. The system of claim 10 or claim 11, wherein the portion of the anti-migration device configured to change shape comprises a plurality of protrusions.

13. 13. The system of claim 11 or claim 12, wherein the at least one protrusion is configured to move from an axially extending position to a radially extending position during implantation of the marking system.

14. The system of any one of claims 11-13, wherein the at least one protrusion comprises a point configured to engage tissue in which the body is implanted and to resist movement of the marking system.

15. The system of any one of claims 1-14, wherein the anti-migration device includes a hollow structure configured to receive a portion of the marker body, and an end of the hollow structure includes a pointed point configured to penetrate hard or bony tissue.

16. The system of any one of claims 1-15, wherein the anti-migration device is formed at least in part from a shape memory material.

17. 17. The system of claim 16, wherein the shape memory material is at least one of silicone, ethylene propylene diene monomer, thermoplastic elastomer, polyether ether ketone, polypropylene, or combinations thereof.

18. The system of claim 16 , wherein the material is nitinol.

19. The system of any one of claims 1-18, wherein the anti-migration device comprises a sheath configured to receive at least a portion of the marker body.

20. 20. The system of claim 19, wherein the sheath has a unitary construction.

21. 20. The system of claim 19, wherein the sheath includes a first sheath portion and a second sheath portion.

22. The system of any one of claims 19-21, wherein the sheath is formed from a braided, woven, mesh, or web-like structure.

23. 23. The system of claim 22, wherein the braided, woven, mesh, or web-like structure has an hourglass shape.

24. 24. The system of claim 22 or claim 23, wherein the braided, woven, mesh, or web-like structure defines an interior within which the marker body is disposed.

25. The system of any one of claims 22-24, wherein the braided, woven, mesh, or web-like structure is configured to engage a distal portion of the marker body or a proximal portion of the marker body.

26. The system of any one of claims 19-25, wherein at least a portion of the sheath is configured to expand radially away from an outer surface of the marker body during implantation.

27. The system of claim 1 , wherein the anti-migration device includes a portion configured to transition between a tensioned state and an expanded state.

28. 2. The system of claim 1, wherein the anti-migration device is formed from one or more wires, the one or more wires forming a helical body having a radially expanded and protruding main portion and two radially fixed end portions, the radially fixed end portions of the helical body configured to firmly grip the marker body.

29. 1. A deployment system, comprising:

1. A deployment device, comprising: a handle portion including an actuator configured to cause a deployment action; a cannula attached to the handle portion at a first end of the cannula and terminating in a cannula end at a second end of the cannula opposite the first end; a deployment device including: a marking system disposed within the lumen of the cannula; Equipped with The marking system comprises: A marker body having an outer surface, the marker body comprising: a transponder configured to respond to electromagnetic radiation from an external source; a microchip operatively connected to said transponder and configured to operate in response to said electromagnetic radiation; a marker body including: an anti-migration device configured to receive at least a portion of the marker body; Including, A deployment system, wherein the anti-migration device is configured to resist migration of the marker body after implantation of the marking system into tissue.

30. 30. The deployment system of claim 29, wherein the marker body is at least partially disposed within the anti-migration device while disposed within the lumen of the cannula.

31. 30. The deployment system of claim 29, wherein the anti-migration device is axially displaced from the marker body within the lumen of the cannula.

32. a first portion of the anti-migration device axially displaced in a first direction from the marker body within the lumen of the cannula; 30. The deployment system of claim 29, wherein the second portion of the anti-migration device is axially displaced within the lumen of the cannula from the marker body in a second direction opposite the first direction.

33. The deployment system of any one of claims 29-32, wherein the deployment device further comprises a lubricant configured to facilitate relative movement between the marking system and the lumen of the cannula.

34. 1. A method of marking a target location within a patient's body, the method comprising: positioning a distal end of a cannula adjacent to the target and below a tissue surface, wherein a tissue marker and an anti-migration device are disposed within a lumen of the cannula; deploying the tissue marker and the anti-migration device at the target location; expanding a portion of the anti-migration device to engage tissue at the target location to anchor the tissue marker at the target location; A method comprising:

35. 35. The method of claim 34, wherein expanding a portion of the anti-migration device to engage tissue at the target location comprises releasing at least one wire portion of the anti-migration device from a compressed state and engaging the tissue at the target location with the at least one wire portion of the anti-migration device.

36. 35. The method of claim 34, wherein expanding a portion of the anti-migration device to engage tissue at the target location comprises radially expanding a sheath portion of the anti-migration device from a compressed state and engaging the tissue at the target location with the radially expanded sheath portion of the anti-migration device.

37. The method of any one of claims 34-36, further comprising positioning at least a portion of the tissue marker within an interior portion of the anti-migration device.

38. 38. The method of claim 37, wherein positioning at least a portion of the tissue marker within an interior portion of the anti-migration device occurs after expanding a portion of the anti-migration device to engage tissue at the target location.

39. 38. The method of claim 37, wherein positioning at least a portion of the tissue marker within the interior portion of the anti-migration device occurs prior to expanding a portion of the anti-migration device to engage tissue at the target location.

40. 40. The method of any one of claims 34-39, wherein the anti-migration device is in a compressed state when disposed within the lumen of the cannula.

41. 41. The method of any one of claims 34-40, further comprising pre-assembling the tissue marker and the anti-migration device into a deployment package prior to positioning the distal end of the cannula.

42. 42. The method of claim 41, wherein pre-assembling the tissue marker and the anti-migration device into a deployment package comprises attaching the anti-migration device to the tissue marker by at least one of a spring force, an overmolding process, a shrink tubing process, a glue bond, a friction fit, a form fit, or a solvent bonding process.

43. Deploying the tissue marker and the anti-migration device comprises: deploying the anti-migration device at the target location; subsequently deploying the tissue marker at the target location; 41. The method of any one of claims 34-40, comprising:

44. 44. The method of any one of claims 34-40 or 43, wherein deploying the tissue marker at the target location comprises positioning a portion of the tissue marker within the anti-migration device following deployment of the anti-migration device.

45. 45. The method of claim 44, wherein positioning at least a portion of the tissue marker within the interior of the anti-migration device occurs prior to expanding a portion of the anti-migration device to engage tissue at the target location.

46. 45. The method of claim 44, wherein positioning at least a portion of the tissue marker within the interior of the anti-migration device occurs after expanding a portion of the anti-migration device to engage tissue at the target location.

47. Deploying the tissue marker and the anti-migration device comprises: deploying a first portion of the anti-migration device at the target location; deploying the tissue marker at the target location subsequent to deploying the first portion of the anti-migration device; deploying a second portion of the anti-migration device at the target location following the deployment of the tissue marker.

41. The method of any one of claims 34-40, comprising:

48. 48. The method of claim 47, wherein deploying the tissue marker at the target location comprises positioning a portion of the tissue marker within the first portion of the anti-migration device.

49. 49. The method of claim 47 or claim 48, wherein deploying the second portion of the anti-migration device at the target location comprises positioning a portion of the tissue marker within the second portion of the anti-migration device.

50. 50. The method of any one of claims 47-49, wherein expanding a portion of the anti-migration device to engage tissue at the target location comprises expanding the first portion of the anti-migration device prior to deploying the tissue marker.

51. 51. The method of any one of claims 47-50, wherein expanding a portion of the anti-migration device to engage tissue at the target location further comprises expanding the second portion of the anti-migration device subsequent to deploying the tissue marker.

52. The method of any one of claims 34-51, wherein the tissue marker is a passive integrated transponder (PIT) tag.

53. 1. A localization marker device for implantation in tissue, said device comprising: an implantable marker having a body with an outer surface, the implantable marker being a transponder, a reflector, an active marker, a magnetic marker, a radioactive seed, a Doppler marker, a passive marker, a wireless tumor localization implant, or a combination thereof; an anti-migration device configured to receive at least a portion of the body of the marker and at least partially engage the outer surface of the body of the marker; Equipped with The anti-migration device includes a portion configured to transition between a first state and a second state, wherein in the first state, the anti-migration device is configured to be disposed within a lumen of a cannula, and in the second state, the anti-migration device is configured to provide resistance to migration to the implantable marker after deployment from the cannula.

54. 54. The device of claim 53, wherein the anti-migration device comprises at least one surface feature configured to increase the resistance to migration.

55. 55. The device of claim 53 or claim 54, wherein the anti-migration device comprises a first anti-migration device portion and a second anti-migration device portion.

56. 56. The device of claim 55, wherein the first anti-migration device portion is axially displaceable from the implantable marker in a first direction and the second anti-migration device portion is axially displaceable from the implantable marker in a second direction opposite the first direction.

57. 57. The device of any one of claims 53-56, wherein the anti-migration device has a mesh structure.

58. 58. The device of claim 57, wherein the mesh structure has an hourglass shape from a side view.

59. 59. The device of claim 57 or claim 58, wherein the mesh structure defines an interior within which the implantable marker is disposed.

60. 60. The device of any one of claims 57-59, wherein the mesh structure is configured to engage one of a distal portion or a proximal portion of the implantable marker.

61. 61. The device of any one of claims 57-60, wherein the mesh structure is a cage that surrounds the implantable marker.

62. 54. The device of claim 53, wherein the anti-migration device comprises a nitinol wire with at least one barb.

63. 54. The device of claim 53, wherein the anti-migration device comprises a tube with a cutout portion, the cutout portion forming at least one barb.

64. 54. The device of claim 53, wherein the anti-migration device comprises a helical body formed from one or more wires.

65. 65. The device of claim 64, wherein when the anti-migration device is in the second state, the helical body forms a plurality of flanged portions, the plurality of flanged portions extending in different radial directions from the marker body when viewed in an axial direction.

66. 54. The device of claim 53, wherein in the first state, the anti-migration device is compressed and in the second state, the anti-migration device is expanded.

67. 54. The device of claim 53, wherein in the first state, the anti-migration device is tensioned and in the second state, the anti-migration device is expanded.

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