Implantable markers

Abstract

An implantable marker for marking an area of ​​tissue in an animal or human body, the implantable marker having at least one wire made of a biocompatible material, the wire having a spatial shape memorized by a molding method, the wire presenting the memorized spatial shape after a compressed spatial shape imposed on the wire by an external mechanical constraint and after the mechanical constraint is removed. The present invention is characterized in that the spatial shape memorized by the wire includes at least two fixed wire holes, the at least two fixed wire holes are respectively formed by at least one spiral winding of the wire, and the shapes and / or spatial relative positions of the at least two fixed wire holes are different in the compressed spatial shape imposed by the external mechanical constraint and in the memorized spatial shape after the mechanical constraint is removed.

Description

Technical Field

[0001] The present invention relates to an implantable marker for marking an internal tissue region of an animal or a human being, wherein the implantable marker has at least one line made of a biocompatible material, wherein the line has a spatial shape memorized by a molding method, and after a compressed spatial shape is imposed on the line by an external mechanical constraint, the line presents the memorized spatial shape after the mechanical constraint is removed. Background Art

[0002] This type of implantable marker is used to mark tumors in human or animal soft tissue. For example, usually after a breast biopsy, the marker is introduced into the location of tissue removal by means of a capillary tube and after reaching the desired position, it is pushed out from the distal end of the capillary tube by means of a stylet. The marker placed in the body remains fixed in position and provides the doctor with the possibility of locating and observing the tissue area to be treated and / or diagnosed for a long time by means of imaging methods, preferably by means of ultrasound images.

[0003] For this reason, a kind of tissue marker for human tissue is obtained by publication US 6,053,925, which has two wires twisted with each other and made of shape memory metal. The marker placed in the tissue area to be marked as much as possible has an annular or coiled shape for this purpose.

[0004] The publication US 2005 / 0059888 A1 discloses a marker which marks the position of a bioabsorbent body placed in the body. The marker consists of a material which can be detected by mammography, radiology and ultrasound examination, for example a thread placed on the absorbent body.

[0005] US 2001 / 0023322 A1 discloses a tubular positioning unit for an insertable marker. The marker consists of a shape memory wire which, after positioning in vivo, is annularly or coil-shaped at least at the wire tip for fixed positioning in the tissue region to be marked.

[0006] Finally, publication EP 1 871 266 B1 discloses a marker of the type described for human or animal tissue, which is made in annular shape from a preprogrammable material, preferably a nickel-titanium alloy, and which returns to the preprogrammed annular shape after a longitudinal extension imposed on the marker and after release.

[0007] All known markers of this type, and in particular the aforementioned annular markers, are ultrasonic reflectors due to their material properties, and the known markers are imaged with different intensities by means of ultrasonic imaging depending on the direction of incidence, along which the ultrasonic waves interact with the marker. If a predominantly planarly propagating ultrasonic field strikes the aforementioned annular marker, whose annular plane is oriented perpendicular to the planar plane of the propagating ultrasonic waves, only two point-like ultrasonic reflection signals are imaged, which reproduce the annular contour when the ultrasonic field is deflected relative to the annular marker. If, on the other hand, the planar ultrasonic field is oriented parallel to the annular plane, the possible reflection signals form a straight line on the ultrasonic image with a length corresponding to the diameter of the annular marker.

[0008] Therefore, a great deal of experience is required to unambiguously identify such markers, which are known per se and whose dimensions lie in the range of a few millimeters, in a spatially and spatially resolved manner in the biological tissue environment. Summary of the invention

[0009] The object of the present invention is to provide an implantable marker for marking an internal tissue region of an animal or a human, the implantable marker having at least one line made of a biocompatible material, the line having a spatial shape memorized by a shaping method, the line assuming the memorized spatial shape after a compressed spatial shape imposed on the line by an external mechanical constraint after the mechanical constraint is removed, the implantable marker being further developed in such a way that the visibility of the implanted marker for the physician during an ultrasound examination should be significantly improved. The marker should be characterized in particular by a high ultrasound reflectivity that is as isotropic as possible, independent of the direction from which the ultrasound head is to be irradiated, so that the marker should be visually clearly and easily located for the physician by means of ultrasound-based imaging methods.

[0010] The solution to the object on which the invention is based is specified in claim 1. Advantageous features that further develop the inventive concept emerge from the subject matter of the dependent claims and from the description with reference to an exemplary embodiment in conjunction with the drawing.

[0011] According to the solution, the implantable marker having the features of the preamble of claim 1 is characterized in that the spatial shape remembered by the wire comprises at least two fixed wire holes, each of which is formed by at least one spiral winding of the wire, and the shapes and / or the spatial relative positions of the at least two fixed wire holes to each other are different in a compressed spatial shape imposed by an external mechanical constraint and in a memorized spatial shape after removal of the mechanical constraint.

[0012] The term "fixed wire hole" comes from knotting technology and is a simple geometric shape that is characterized by the formation of a circle along the wire. In this case, the wire is wound helically at least once and has a helical slope at which the wires touch in the overlapping region of the windings. In contrast to a closed annular shape, a fixed hole is not a straight line with a constant wire thickness during lateral ultrasonic injection, but a wedge-shaped or double-wedge-shaped hole, the maximum wedge thickness of which corresponds to double the wire width in the case of a single helical winding. Accordingly, it is more obvious that an ultrasonic signal is formed during lateral injection into a fixed wire hole consisting of a plurality of helical windings.

[0013] The implantable marker according to the solution has at least two, preferably three or more wire holes, which are respectively formed by spiral windings of the wire along the wire. At least two fixed wire holes optionally, but advantageously, have the same shape and size. Of course, hole shapes other than circular, such as egg-shaped or elliptical fixed holes are also conceivable. The shape and size of the wire holes arranged along the wire can also be different from each other. In addition, the spatial orientation and configuration of the fixed wire holes can be selected uniformly or individually by the spacing of the fixed wire holes from each other and the orientation of the planes of the respectively configurable fixed wire holes.

[0014] Metallic shape memory materials are particularly suitable for producing the wire and for stamping the solution-dependent spatial shape along the wire, and preferably have pseudo-elastic properties, that is, even if the wire is strongly deformed elastically under the action of external forces, the wire composed of the shape memory material returns to the spatial shape of the wire memorized by the high-temperature process in a shape-retaining manner. Particularly suitable materials are nickel titanium ("Nitinol"), nickel titanium copper, copper zinc, copper zinc aluminum or copper aluminum nickel.

[0015] In a possible embodiment of the implantable marker according to the solution, the wire has two fixed wire holes, which are integrally connected to each other via a wire section. For positioning in the body, the wire is transformed into a compressed spatial shape by external mechanical constraints, in which at least one helical winding of the wire hole is completely stretched by a tensile force acting along the wire, that is, the winding is largely completely elastically deformed while forming a linear wire. In the compressed shape, the wire is inserted into a hollow capillary, through which the wire can be positioned in the body.

[0016] The application of the wire is achieved in a manner known per se with the aid of a stylet. As soon as the wire in the compressed spatial shape is pushed out of the hollow capillary at the distal end, the wire spontaneously occupies its memorized spatial shape and spontaneously forms two fixed wire holes. According to the memorized spatial shape, the wire holes can correspondingly unfold a common hole plane. It is preferably proposed that the individual fixed wire holes are oriented along the wire with respectively different hole planes, that is, a torsional, material-inherent material stress is applied along the wire section that integrally connects the two fixed wire holes to each other, and the two fixed wire holes are oriented torsionally relative to each other.

[0017] Alternatively or in combination with the aforementioned twisting of the two fixed cable eyelets integrally connected to one another via a cable section, a further embodiment provides for tilting or pivoting the two fixed cable eyelets by a locally memorized bend along the cable section integrally connecting the two fixed cable eyelets to one another.

[0018] In a further embodiment, at least two fixed wire holes are integrally connected via a wire segment, so that the at least two fixed wire holes are arranged side by side without overlap along a virtual straight axis in a compressed spatial shape imposed by an external mechanical constraint. In the described state, the fixed wire holes are pushed into a hollow capillary sized to correspond to the hole diameter and implanted into the body at the distal end through the hollow capillary with the aid of a stylet as already described in the previous case. Directly after being pushed out of the hollow capillary, the implantable marker undergoes spontaneous elastic deformation in its memorized spatial shape. In the case of two fixed wire holes that are integrally connected to each other via a wire segment, the two fixed wire holes can individually assume their initial memorized shape and / or size and also their spatial orientation relative to each other.

[0019] In a further preferred embodiment, at least three fixed wire holes are constructed along the wire, which are arranged one after the other in series along a virtual linear axis in a compressed spatial shape imposed by an external mechanical constraint. In the compressed spatial shape, the implantable marker can be positioned in the body by a hollow capillary tube of suitably determined dimensions. Once the mechanical constraint acting on the marker by the hollow capillary tube is removed by pushing out at the distal end, the implantable marker assumes its initial memorized spatial shape, which is significantly different from the arrangement of the at least three fixed wire holes in series along the virtual linear axis.

[0020] The exemplary embodiments shown in the drawings can be used to illustrate a number of possible construction variants of a solution-implantable marker having a solution-memorized spatial shape, which is characterized by improved visibility from all spatial directions using ultrasound-based imaging methods.

[0021] In addition to the improved ultrasound-based detectability achieved by the memorized spatial shape of the implantable marker, a surface structure preferably arranged or processed along the surface of the line also helps to increase the ultrasound reflectivity. The surface structure is preferably characterized by a random or regular arrangement of surface roughening or grooved, grooved and / or cut-shaped recesses on the surface of the line.

[0022] Instead of the embodiment of the implantable marker in the form of a wire made of a metallic shape memory material according to the solution and the spatial shape of the marker memorized according to the solution, it is also proposed that the wire is produced from a suitably selected alternative biocompatible material having the same or similar shape memory properties. For example, shape memory polymers or composite materials are suitable for this purpose, which are provided in combination with a shape memory alloy. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The invention is described below by way of example with reference to the accompanying drawings, without limiting the general inventive concept.

[0024] Figure 1 a shows a first embodiment of an implantable marker in a compressed spatial shape constructed according to the solution,

[0025] Figure 1 b, c show the Figure 1 a, a top view and a side view of an implantable marker with a memorized spatial shape,

[0026] Figure 2 a shows a second embodiment of an implantable marker in a compressed spatial shape,

[0027] Figure 2 b, c, d show the Figure 2 a's implantable markings in the memorized spatial shape, and

[0028] Figure 3 ac show different line surface structures. DETAILED DESCRIPTION

[0029] exist Figure 1 A first exemplary embodiment for an implantable marker designed according to the solution is shown in ac. Figure 1b and c show a marker 1 in its three-dimensional memorized spatial shape in a top view and a side view, respectively. The marker 1 is made of a round wire 2, preferably of Nitinol (NiTi), and has two fixed wire holes or wire holes 3, 4 in its memorized spatial shape. The wire holes 3, 4 are each made by a single-strand helical winding along the wire made of Nitinol. The winding directions of the two wire holes 3, 4 are each oriented in opposite directions.

[0030] In order to position the implantable marker 1 in the body, the marker 1 is transformed into Figure 1 In the linearly stretched, compressed spatial shape shown in a. To this end, the nitinol wire 2 is Figure 1 The memorized spatial shapes shown in b and c are stretched in the longitudinal direction of the wire under the action of tensile force and introduced into the hollow capillary 5 .

[0031] The wire 2 in the compressed spatial shape is pushed through the distal opening 7 of the hollow capillary 5 by means of the stylet 6. Immediately after the marker 1 is pushed through the distal opening 7 of the hollow capillary 5, the marker 1 presents Figure 1 b and c show the memorized spatial shape. The two fixed wire holes 3, 4 connected to each other in one piece by the wire section 8 each have a hole plane E1, E2 located in the plane of the drawing. Of course, the hole planes E1, E2 assigned to the fixed wire holes 3, 4 can also be oriented obliquely or twisted relative to each other. For this purpose, it is suitable to set a corresponding mechanical material-inherent prestress along the wire section 8, which causes the two fixed wire holes 3, 4 to twist relative to each other, see for this purpose in Figure 1 Arrow view P1 in b. Instead of the aforementioned twisting or in combination with the twisting, along Figure 1 The straight-line wire sections 8 in b, c can incorporate mechanically preprogrammed wire bends, such as this by Figure 1 As described by the arrow view P2 shown in c.

[0032] Figure 1 The memorized spatial shape of the implanted marker 1 shown in , which enables easy and reliable detection by means of ultrasound-based imaging methods, independently of the spatial orientation of the implanted marker 1 relative to the ultrasound field radiated into the body in each case.

[0033] Figure 2 ad shows a preferred extended variant for forming a marker 1 that can be implanted according to the solution, from different viewing angles. Figure 2 The memorized spatial shape of the implantable marker is shown in bd.

[0034] The implantable marker 1 in this case has five fixed wire holes or wire holes 9-13, each of which is preferably made in one piece from a nitinol wire 2. Figure 2 As can be seen, the fixed wire holes 10 and 12 are respectively provided with more than one spiral winding. The number of windings of the fixed wire holes can be variably selected at will. The number of wire holes along the wire 2 and the spacing and orientation of the wire holes from each other can also be selected at will.

[0035] exist Figure 2 FIG. 1 shows a compressed spatial shape of an implantable marker 1, in which fixed wire holes 9 to 13 are arranged linearly along a virtual linear axis 14 under external mechanical tension constraints, so that the wire holes can be introduced into the hollow capillary 5. Once the marker 1 in the compressed spatial shape is pushed out of the hollow capillary 5 at the distal end by means of the stylet 6, the marker 1 suddenly, i.e. spontaneously, appears. Figure 2 bd shows the memorized spatial shape. In this case, the fixed wire holes 9-13 together with the wire segments 8 form a three-dimensionally determined structure or spatial shape, which generates a significant reflection signal in the interaction with the ultrasound field, and which appears visually clearly in the ultrasound image. In addition, the implantable marker 1 constructed according to the solution can be used due to the Figure 2 The compressed spatial shape shown in a suddenly transitions to Figure 2 In the memorized spatial shape shown in FIG. 2 bd , a close and mechanically stable connection with the biological tissue surrounding the marking 1 is established, so that an undesired migration of the implanted marking 1 within the tissue can be excluded right from the outset.

[0036] Just for the sake of completeness, the implantable marker 1 Figure 2 The memorized spatial shapes shown in bd can also be differently introduced with twists or bends along the wire sections 8, see Figure 1 b, c Arrow views P1, P2.

[0037] In order to be able to improve the ultrasound reflectivity of the implantable marker 1 according to the solution, the surface 15 of the thread or wire 2 of which the marker 1 is formed is structured. Possible surface structures of the thread or wire 2 are Figure 3 As shown in ac. Figure 3 a shows a groove-shaped embossing 17 which extends along the line or wire surface 15. Figure 3 In b, the wire surface 15 is provided with a plurality of local cutouts 18, which achieve an increased ultrasonic reflectivity. Figure 3 c. A surface structure 19 is provided which is grooved along the line surface or wire surface 15 .

[0038] The individual features known from the various exemplary embodiments can be combined as desired. The lengths of the correspondingly identically dimensioned wire sections 8 are Figure 2 The dimensions a to d can also be determined individually without taking into account disadvantages with regard to ultrasound reflectivity.

[0039] Although it can Figure 2 The wire holes known from the top view in b are located in the projection on an equilateral triangle D and thus form a mathematically defined or geometrically determined recognition pattern, which is particularly suitable for autonomous image evaluation, but the following design parameters of the spatial shape memorized in the implant 1 can be selected arbitrarily:

[0040] - diameter d of the wire hole,

[0041] - length L of the wire segment,

[0042] - Angles α, β between the wire segments 8, see Figure 2 c, d,

[0043] -Number of spiral turns per thread hole

[0044] - The geometric shape of each wire hole: round, oval, egg-shaped, n-gonal

[0045] - The winding direction of the helical winding.

[0046] Reference numerals list

[0047] 1 Implantable markers

[0048] 2 wires or threads

[0049] 3, 4 fixed holes

[0050] 5 Hollow capillary

[0051] 6 Stylet

[0052] 7 Distal opening

[0053] 8 Wire segment, silk segment

[0054] 9-13 Fixed holes

[0055] 14 Virtual linear axis

[0056] 15 Line surface or silk surface

[0057] 16 Groove-shaped molded portion

[0058] 17 Local incision

[0059] 18 Grooved surface structure

[0060] D Equilateral triangle

[0061] d Hole with fixed diameter

[0062] L Length of the wire segment or wire segment

[0063] α, β Angle between filament segments.

Claims

1. An implantable marker (1) for marking an internal tissue region of an animal or a human, the implantable marker having at least one thread (2) made of a biocompatible material, the thread having a spatial shape memorized by a molding method, the thread (2) assuming the memorized spatial shape after the mechanical constraint is removed from the compressed spatial shape imposed on the thread by an external mechanical constraint, in, The memorized spatial shape of the wire (2) comprises at least three fixed wire holes (9, 10, 11), each of which is formed by at least one spiral winding of the wire (2), the at least three fixed wire holes are connected to each other in one piece via a wire segment (8), and the shapes and / or spatial relative positions of the at least three fixed wire holes are different in the compressed spatial shape and in the memorized spatial shape, Characterized in that the at least three fixed wire holes (9, 10, 11) are constructed along the wire (2), the at least three fixed wire holes are arranged in series one after the other in a straight line along a virtual straight axis (14) in the compressed spatial shape and arranged side by side without overlap in a hollow capillary (5), the hollow capillary applying an external mechanical constraint to the wire (2), and After being pushed out of the hollow capillary (5) and the mechanical constraint is removed, the at least three fixed wire holes (9, 10, 11) occupy a spatially different arrangement in the memorized spatial shape than the arrangement in series along the virtual straight axis (14), whereby the implantable marker (1) can establish a tight and mechanically stable connection with the tissue area surrounding the marker (1) due to the transition of the compressed spatial shape into the memorized spatial shape.

2. The implantable marker according to claim 1, characterized in that The winding direction of at least one helical winding of a fixed wire eyelet (9, 10, 11) is different between two wire eyes (9, 10, 11) arranged along the wire (2).

3. The implantable marker according to claim 1 or 2, characterized in that Each fixed wire hole (9, 10, 11) can be provided with a hole opening plane (E1, E2), The hole opening plane (E1, E2) of at least one fixed wire hole (9, 10, 11) is not oriented parallel to the hole opening plane (E1, E2) of at least one other wire hole (9, 10, 11) in the memorized spatial shape, or The hole opening planes (E1, E2) of all the wire holes (9, 10, 11) are oriented parallel in the memorized spatial shape.

4. The implantable marker according to claim 1 or 2, characterized in that The biocompatible material of the thread (2) consists of a material that reflects ultrasound waves.

5. The implantable marker according to claim 1 or 2, characterized in that The wire (2) has a wire surface, on which surface structures (16, 17, 18) that reflect ultrasound waves are at least partially arranged.

6. The implantable marker according to claim 1 or 2, characterized in that The thread (2) made of biocompatible material has at least one material with shape memory properties.

7. The implantable marker according to claim 1 or 2, characterized in that The wire (2) made of biocompatible material is a wire made of a metallic shape memory material from the following group: NiTi ("Nitinol"), NiTiCu, CuZn, CuZnAl or CuAlNi.

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