Patent Publication Number: US-2011071423-A1

Title: Flexible biopsy marker delivery device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application cross references and incorporates by reference commonly assigned U.S. patent application Ser. No. 12/196,301 filed Aug. 22, 2008. 
    
    
     BACKGROUND 
     Biopsy samples have been obtained in a variety of ways in various medical procedures using a variety of devices. An exemplary biopsy device is the MAMMOTOME® brand device from Ethicon Endo-Surgery, Inc. of Cincinnati, Ohio. Biopsy devices may be used under stereotactic guidance, ultrasound guidance, MRI guidance, or otherwise. 
     Further exemplary biopsy devices are disclosed in U.S. Pat. No. 5,526,822, entitled “Method and Apparatus for Automated Biopsy and Collection of Soft Tissue,” issued Jun. 18, 1996; U.S. Pat. No. 6,086,544, entitled “Control Apparatus for an Automated Surgical Biopsy Device,” issued Jul. 11, 2000; U.S. Pub. No. 2003/0109803, entitled “MRI Compatible Surgical Biopsy Device,” published Jun. 12, 2003; U.S. Pub. No. 2007/0118048, entitled “Remote Thumbwheel for a Surgical Biopsy Device,” published May 24, 2007; U.S. Provisional Patent Application Ser. No. 60/869,736, entitled “Biopsy System,” filed Dec. 13, 2006; U.S. Provisional Patent Application Ser. No. 60/874,792, entitled “Biopsy Sample Storage,” filed Dec. 13, 2006; and U.S. Non-Provisional patent application Ser. No. 11/942,785, entitled “Revolving Tissue Sample Holder for Biopsy Device,” filed Nov. 21, 2007. The disclosure of each of the above-cited U.S. patents, U.S. Patent Application Publications, U.S. Provisional Patent Applications, and U.S. Non-Provisional patent application is incorporated by reference herein. 
     In some settings, it may be desirable to mark the location of a biopsy site for future reference. For instance, one or more markers may be deposited at a biopsy site before, during, or after a tissue sample is taken from the biopsy site. Exemplary marker deployment tools include the MAMMOMARK®, MICROMARK®, and CORMARK® brand devices from Ethicon Endo-Surgery, Inc. of Cincinnati, Ohio. Further exemplary devices and methods for marking a biopsy site are disclosed in U.S. Pub. No. 2005/0228311, entitled “Marker Device and Method of Deploying a Cavity Marker Using a Surgical Biopsy Device,” published Oct. 13, 2005; U.S. Pat. No. 6,996,433, entitled “Imageable Biopsy Site Marker,” issued Feb. 7, 2006; U.S. Pat. No. 6,993,375, entitled “Tissue Site Markers for In Vivo Imaging,” issued Jan. 31, 2006; U.S. Pat. No. 7,047,063, entitled “Tissue Site Markers for In Vivo Imaging,” issued May 16, 2006; U.S. Pat. No. 7,229,417, entitled “Methods for Marking a Biopsy Site,” issued Jun. 12, 2007; U.S. Pat. No. 7,044,957, entitled “Devices for Defining and Marking Tissue,” issued May 16, 2006; U.S. Pat. No. 6,228,055, entitled “Devices for Marking and Defining Particular Locations in Body Tissue,” issued May 8, 2001; and U.S. Pat. No. 6,371,904, entitled “Subcutaneous Cavity Marking Device and Method,” issued Apr. 16, 2002. The disclosure of each of the above-cited U.S. patents and U.S. Patent Application Publications is incorporated by reference herein. 
     It may be desirable to deploy markers from a cannula type deployer into the biopsy site, such as a flexible tubular deployer. The marker should not unintentionally fall out of the deployer, and the force to deploy the marker should not be excessive. Further, the tubular deployer should not advance further within the biopsy device than intended. 
     SUMMARY 
     In one non limiting aspect, the present invention provides a flexible biopsy marker deployer comprising an tube carrying at least one biopsy marker, and inner pushing member such as push rod. The push rod is disposed within the outer tube and is advanceable within the tube to urge the marker out of the deployer. 
     In some instances, it may be desirable to bend the flexible marker deployer, such as when the marker element is inserted through a curved path in a biopsy device to deliver a biopsy marker to a biopsy site within the body. Without being limited by theory, it is desirable that the push rod not be too loose within the deployer tube, and also that the push rod not be too tight within the deployer tube, in order reduce the forces required to deploy the marker element. Applicants have found that in certain circumstances, despite efforts to closely control the relative dimensions of the push rod and the inner diameter of the deployer tube, and despite providing a generous clearance between the push rod and the inner surface of the tube, the push rod may become stuck or otherwise “locked” within the tube if the tube is bent. Such locking can result in deployment forces that are unacceptably high, and may even prevent advancement of the push rod within the tube, such that the marker is not deployable from the tube. 
     Further, without being limited by theory, applicants have determined that such locking may be a form of “friction locking” between the outer surface of the push rod and the inner surface of the deployer tube. 
     In one embodiment of the present invention, the Applicants have provided a pushing member disposed within a marker deployer tube, where the pushing member has a reduced surface contact area with respect to the inner surface of the tube, as compared to generally smooth, cylindrical shaped pushing member. The pushing member can have a surface feature and/or surface roughness that is different from that of the inner surface of the deployer tube. For instance, the pushing member may have a surface roughness greater than the surface roughness of the inner surface of the deployer tube. 
     In one embodiment, the pushing member may have a surface feature in the form of repeating raised portions, such as longitudinally extending ribs, longitudinally spaced apart rings, or a generally uniform repeating pattern of bumps or protrusions on the outer surface of the push rod. Alternatively, the surface feature may be in the form a generally non-uniform and non repeating texturing. In yet another alternative embodiment, the surface of the push rod may be generally smooth, and the inner surface of the deployment tube may have a surface feature for reducing the contact surface area between the push rod and the inner surface of the deployment tube. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       It is believed the present invention will be better understood from the following description of certain examples taken in conjunction with the accompanying drawings, in which like reference numerals identify the same elements and in which: 
         FIG. 1  depicts a perspective view of a marker delivery device of the type illustrated in U.S. patent application Ser. No. 12/196,301 filed Aug. 22, 2008; 
         FIG. 2  depicts a cross-sectional view of a distal portion of a marker delivery device of the type illustrated in U.S. patent application Ser. No. 12/196,301 filed Aug. 22, 2008. 
         FIG. 3  depicts a marker being deployed from a deployer and through a lateral tissue receiving port in a biopsy needle to mark a biopsy site, such as illustrated in U.S. patent application Ser. No. 12/196,301 filed Aug. 22, 2008. 
         FIG. 4  depicts a portion of a marker deployer according to one embodiment of the present invention, where a portion of the deployment tube is shown cutaway to illustrate the inner diameter of the tube is generally smooth, and to reveal a member, such as a push rod, the push rod having a surface feature effective for reducing the contact surface area between a portion of the push rod disposed within the deployment tube and the inner surface of the deployment tube, and  FIG. 4  showing a push rod having a surface finish and surface roughness different than those of the inner diameter of the tube, the push rod shown having a plurality of generally longitudinally extending ribs having peaks elevated above relatively lower elevation depressions. 
         FIG. 5 . Depicts a cross-section of the pushing member and illustrating the peaks of the elevated portions of the longitudinally extending ribs in relation to the diameter of the pushing member and in relation to the recessed portions of the outer surface of the push rod. 
         FIG. 6  depicts a cross-section of the deployer of  FIG. 1  with the pushing member shown disposed within the deployer tube, and illustrating the circumferential peak to peak spacing of adjacent lontigudinally extending ribs can be greater than the radial height of the ribs. 
         FIG. 7  illustrates a pushrod having a relatively rigid proximal portion  18 A (such as stiffened by a metal sleeve) and a relatively flexible distal portion  18 B comprising a plurality of longitudinally extending ribs. 
         FIG. 8  illustrates a plurality of ring like ribs providing spaced apart raised surfaces disposed on the outer surface of a push rod, adjacent ring like ribs spaced longitudinally from one another along a portion of the push rod disposed within the deployment tube. 
         FIG. 9  illustrates an embodiment having a surface feature on the inside surface of the cannula lumen. 
     
    
    
     DETAILED DESCRIPTION 
     The following description of certain examples of the invention should not be used to limit the scope of the present invention. Other examples, features, aspects, embodiments, and advantages of the invention will become apparent to those skilled in the art from the following description, which is by way of illustration, one of the best modes contemplated for carrying out the invention. As will be realized, the invention is capable of other different and obvious aspects, all without departing from the invention. Accordingly, the drawings and descriptions should be regarded as illustrative in nature and not restrictive. 
       FIGS. 1-3  illustrate a marker delivery device  10  of the type illustrated in U.S. patent application Ser. No. 12/196,301 filed Aug. 22, 2008. Marker delivery device  10  may include a tubular elongate outer cannula  12  having a marker exit, such as side opening  14  formed near to, but spaced proximally from, the distal end of the cannula  12 . 
     A grip  16  can be provided at the proximal end of cannula  12 . A pushing member in the form of a push rod  18  can be provided, with push rod  18  extending coaxially in cannula  12  such that the push rod  18  is configured to translate within cannula  12  to displace one or more markers through the side opening  14  (see  FIG. 2 ). Rod  18  can have a proximal portion (proximal portion  18 A in  FIG. 7 ) have sufficient rigidity in compression to push a marker from the internal lumen of cannula  12  out through opening  14 , and include a more distal portion (for example portion  18 B in  FIG. 7 ) that is relatively flexible in bending so that the cannula  12  can be inserted along a curved path to deploy a marker element at a biopsy site. 
     A plunger  20  can be provided at the proximal end of rod  18  for forcing rod  18  distally in cannula  12  to deploy a marker out of the cannula  12 . A user may grasp grip  16  with two fingers, and may push on plunger  20  using the thumb on the same hand, so that the marker delivery device  10  can be operated by a user&#39;s single hand. A spring (not shown) or other feature may be provided about rod  18  to bias rod  18  proximally relative to grip  16  and cannula  12 . 
       FIG. 2  depicts a cross-sectional view of a distal portion of the marker delivery device  10 .  FIG. 2  shows a biopsy marker  300  disposed in the internal lumen  15  of the cannula  12 . The marker  300  can comprise a biodegradable or otherwise resorbable body  306 , such as a generally cylindrically shaped body of collagen, and a metallic, generally radiopaque marker element  310  (shown in phantom) disposed within or otherwise carried by the body  306 . 
     The cannula  12  can be formed of any suitable metallic or non-metallic material. In one embodiment, the cannula  12  is formed of a thin walled hollow tube formed of a suitable medical grade plastic or polymer. One suitable material is a thermoplastic elastomer, such as Polyether block amide (PEBA), such as is known under the tradename PEBAX. The cannula  12  can be formed of PEBAX, and can be substantially transparent to visible light and X-ray. 
     The side opening  14  can be formed by cutting away a portion of the wall of cannula  12 . The side opening  14  communicates with an internal lumen  15  of the cannula. The side opening  14  can extend axially (in a direction parallel to the axis of the lumen  15 ) from a proximal opening end  14 A to a distal opening end  14 B, as illustrated in  FIG. 2 . 
     The distal tip  22  extending from the distal end of cannula  12  can be rounded as shown in  FIG. 2 . Referring to  FIG. 2 , a marker delivery device can have the distal end of the cannula  12  closed by a unitary endpiece  21  formed in place in the distal end of the cannula  12 , with a part of the endpiece  21  extending into the internal lumen  15  of the cannula. The distal endpiece  21  can be a molded or cast component, and can provide an integrally formed combination of the tip  22 , a ramp  210  having a ramp surface  212 , and a marker engaging element  240 . The ramp surface  212  aids in directing the marker  300  from the internal lumen  15  through side opening  14 . The marker engaging element  240  may be employed to retain the marker  300  in the internal lumen  15  until the user intends to deploy the marker. 
     The marker engaging element  240  may be disposed within the internal lumen  15 , and at least a portion of the marker engaging element is disposed distally of the proximal end  14 A of side opening  14 . The marker engaging element  240  can extend along a portion of the floor of the cannula  15  under the opening  14 , and the marker engaging element  240  can be positioned to reinforce the portion of the cannula in which the opening  14  is formed. For instance, by positioning the marker engaging element  240  underneath the opening  14 , as shown in  FIG. 2 , the element  240  can help to stiffen the cannula  12  in the region where wall of the cannula  12  is cut to form the opening  14 . In  FIG. 2 , the marker engaging element  240  extends from the proximal most portion of ramp surface  212 , and does not extend proximally of the side opening  14 , though in other embodiments, a portion of the element  240  could extend proximally of the opening  14 . 
     In the embodiment shown in  FIG. 2 , marker engaging element  240  is in the form of a step having a generally uniform thickness T along the element&#39;s axial length, except that the element has a tapered proximal end  242 . The tapered proximal end  242  can form an included angle with the longitudinal axis of the lumen  15  (included angle with a horizontal line in  FIG. 2 ) of about 45 degrees, while the ramp surface  212  can form an included angle with the longitudinal axis of about 30 degrees. 
     The thickness T can be greater than the wall thickness t of the cannula  12 , and in one embodiment T is at least about twice the thickness t. In one embodiment, the thickness T can be between about 0.018 inch to about 0.040 inch, and the wall thickness t can be between about 0.005 inch to about 0.008 inch. The internal diameter of lumen  15  can be about 0.120 inch. 
     In  FIG. 2 , the upwardly facing surface  244  (surface facing the opening  14 ) marker engaging element  240  extends distally to contact the ramp surface  212 , so that there is not a space or gap between the surface  244  and the ramp surface  212 . Such an arrangement is advantageous to reduce the possibility that the marker  300 , upon moving past the marker engaging element, will become lodged between the marker engagement element and the ramp. 
     If desired, the marker engaging element  240 , ramp  210 , and/or the tip  22  can be formed of, or include, a material that is relatively more radiopaque than the wall of the cannula  12 . For instance, where the element  240 , ramp  210 , and tip  22  are formed as an integral endpiece  21 , the endpiece  21  can include a radiopaque additive, such as barium sulfate. For instance, the endpiece  21  can be a component molded of PEBAX, with about 20 percent by weight barium sulfate added to the molten PEBAX mold composition. 
     The relatively more radiopaque marker engaging element  240 , ramp  210 , and tip  22  can be useful in distinguishing the position of those components using radiographic imaging. Also, where the ramp and/or step of engaging element are positioned in association with the opening  14 , the addition of a radiopaque material can help identify the position of the opening, and the position of the marker  300  relative to the opening before, during, or after deployment of the marker. 
     Only one marker is shown disposed in lumen  15  in the figures. However, it will be understood that multiple markers can be disposed in marker delivery device  10 , such as in an end to end configuration. The markers can have the same size and shape, or alternatively have different sizes and/or shapes. 
     The cannula  15  can be generally transparent to visible light and x-ray, and the endpiece  21  can be generally opaque to visible light and x-ray. If desired, the endpiece  21  can be colored with a dye or other suitable colorant in the liquid mold composition. For example, it may be desirable to have different size markers (e.g. length and/or diameter) for different biopsy procedures. For instance, it may be desirable to provide a larger marker if a relatively large biopsy sample is taken, and a smaller marker if a relatively small biopsy sample is taken. The endpiece  21  can be colored using one of multiple colors to indicate the size of the marker disposed in the cannula. For instance, if three marker sizes are provided, the endpiece  21  can be colored one of three colors to identify which of the marker sizes are disposed in the cannula of a particular marker device. The endpiece  21  can also be colored to indicate a particular size (diameter or length) biopsy needle with which the marker delivery device is to be used. Additionally, multiple marker delivery devices could be packaged in kit form, with the kit including marker delivery devices having different size markers and correspondingly colored endpieces. 
     Referring to  FIG. 3 , the marker delivery device  10  may be used to deploy a marker to mark a particular location within a patient. In  FIG. 3 , a cannular biopsy needle  1000  is shown. The needle  1000  is shown having a closed distal end with piercing tip  1002 , and a lateral tissue receiving aperture  1014 . Marker deployer  10  may be introduced to a biopsy site through biopsy needle  1000 , which can be the same needle used to collect a tissue sample from the biopsy site. The biopsy needle  1000  can be of the type used with single insertion, multiple sample vacuum assisted biopsy devices. Several such biopsy devices are disclosed in the various patents and patent applications that have been referred to and incorporated by reference herein, though other biopsy devices may be used. 
       FIG. 3  shows the distal end of a marker deployer  10  disposed within the needle  1000 . The needle  1000  can be positioned in tissue, and a biopsy sample can be obtained through opening  1014 , thereby providing a biopsy cavity adjacent opening  1014 . Then, after the tissue sample has been obtained and transferred proximally through the needle, and without removing the needle  1000  from the patient&#39;s tissue, the deployer  10  can be inserted into a proximal opening in the needle  1000 . In  FIG. 3 , the needle  1000  and deployer  10  are positioned such that opening  14  of cannula  12  and opening  1014  of needle  1000  are substantially aligned axially and circumferentially. Then, with the deployer and needle so positioned at the biopsy site, the push rod  18  can be advanced to deploy the marker up the ramp surface  212 , through the opening  14 , and then through opening  1014 , into the biopsy cavity. 
     In some instances, it may be necessary to bend or otherwise flex the marker deployer cannula  12  and push rod  18  when inserting the deployer into the biopsy device. By reducing the effective contact surface area between the outer surface of the push rod  18  and the inner surface of the cannula  12 , Applicants believe the tendency of the push rod  18  to “lock” within the cannula  12  can be reduced and/or eliminated. 
       FIG. 4  illustrates a marker deployer according to one embodiment of the present invention.  FIG. 5  illustrates a cross-sectional illustration of the push rod  18 .  FIG. 6  illustrates a cross-section of the push rod  18  disposed within the cannula  12 . 
     In  FIG. 4 , a portion of the cannula  12  and push rod  18  are illustrated, with part of the cannula  12  cut away to show the push rod  18  disposed within the cannula  12 . The cannula  12  can be formed from a thin wall, flexible non-metallic tube having a generally smooth outer surface  124 , a generally smooth inner surface  122 , and having an inner diameter designated  126  in  FIG. 4 . A generally flexible, elongate pushing member, such as a portion of push rod  18 , is disposed at least partially within the internal lumen of the hollow cannula  12 . The push rod  18  has an outer diameter designated  186  in  FIG. 4 . 
     In  FIG. 4 , push rod  18  is illustrated having an outer surface  182  that has a surface feature designated generally as  184 , which surface feature is effective for reducing the contact surface area between the outer surface of the push rod  18  and the inner surface of the lumen extending through cannula  12  when the cannula  12  and rod  18  are bent or otherwise flexed. In one embodiment, the surface feature  184  is configured to be effective in providing at least about a 50 percent reduction (still more particularly at least about 75% reduction) in the contact surface area that would otherwise occur for a push rod  18  and cannula  12  both having generally smooth, untextured surfaces and the same nominal outer diameter and inner diameter. 
     In the embodiment shown in  FIG. 4 , surface feature  184  is shown comprising a plurality of longitudinally extending elevated portions in the form of ribs  188 . The ribs  188  extend along at least a portion of the push rod  18  disposed within cannula  12 . 
     For marker deployers  10  useful in connection with breast biopsy devices having a breast biopsy needle, and useful for deploying breast biopsy markers from breast biopsy devices, the inner diameter  126  of the lumen of cannula  12  may be (but is not limited to) at least about 0.08 inch, and the outer diameter  186  of the push rod  18  may be (but is not limited to) between about 0.04 inch and about 0.09 inch. 
     In one embodiment, the ribs  188  can have a radial height  196  measured with respect to adjacent recessed portions (designated as valleys  189 ) of between about 0.0001 inch and about 0.01 inch. More particularly, the ribs  188  can have a radial height of between about 0.0003 inch and about 0.004 inch, yet more particularly, the radial height  196  can be between about 0.0005 inch and about 0.004 inch. In one non-limiting example, the radial height  196  can be between about 0.001 inch and about 0.003 inch, such as about 0.002 inch plus or minus 0.001 inch. The radial height  196  can be less than one tenth of the diameter  186  of the push rod, and more particularly less than about one twentieth of the diameter  186 . The radial height  196  can be less than one half (less than 50 percent of), and more particularly less than about one quarter of the difference between outer diameter  186  and the inner diameter  126  of the lumen of the cannula  12 . 
     The number and size of longitudinal surface features may be selected to be effective in reducing the effective contact surface area between push rod and the inner surface of the cannula, without interfering with sliding of the push rod within the lumen of the cannula. For instance, but without being limited by theory, in one embodiment the push rod  18  may have at least about 20 ribs spaced around it&#39;s circumference, and less than about 100 ribs. The ribs can be formed by extruding, molding, or other suitable methods. The circumferential spacing between adjacent ribs can be greater than the radial height  196  of the adjacent ribs. 
     In one non limiting example, a biopsy marker deployer  10  of the present invention suitable for use through an 11 gauge breast biopsy needle can have a push rod diameter  186  of about 0.060 inch (as measured from tips of splines), a cannula inner diameter  126  of about 0.084 inch, and about 40-50 splines spaced around the circumference of the push rod, the splines being generally uniformly spaced apart and having a radial height of about 0.002 inch. Without being limited by theory, it is believed that such a configuration can be effective in reducing the effective contact area between the cannula  12  and the rod  18  to about 0.246 square inch from about 1.158 square inch. The surface area can be measured using any suitable method, including optical methods employing magnification. The surface area can be measured using a comparator (an inspection device that illuminates a part, such as a Top Bench Contour Projector available from Optical Gauging Products, Inc.) and overlay, where the overlay is constructed to match the desired spline or surface area characteristics. A laser interferometer or stylus based surface roughness tester can also be used to measure surface features. 
     In another non limiting example, a biopsy marker deployer  10  of the present invention suitable for use in an 8 gauge breast biopsy needle can have a push rod diameter  186  of about 0.082 inch, a cannula inner diameter  126  of about 0.120 inch, and about 50-70 splines spaced around the circumference of the push rod, the splines being generally uniformly spaced apart and having a radial height of about 0.002 inch. Without being limited by theory, it is believed that such a configuration can be effective in reducing the effective contact area between the cannula  12  and the rod  18  to about 0.388 square inch from about 1.665 square inch. 
       FIG. 7  illustrates a push rod  18  having a relatively stiff proximal section  18 A, and a flexible portion  18 B comprising a plurality of ribs  188  as described above. The relatively stiff proximal portion  18 A can comprise a metallic sleeve or other stiffening member disposed at the proximal end of the rod to prevent the proximal end of the push rod from bending or kinking when plunger  20  is pressed to deploy a marker. The flexible portion  18 B may comprise ribs  188  or other surface features along some or substantially all the length of flexible portion  18 B such as to be effective in preventing locking of the push rod  18  within cannula  12  when the rod and cannula are bent or otherwise disposed along a curved path. 
       FIG. 8  illustrates an alternative embodiment comprising surface features  1188  disposed at spaced apart locations along the length of the push rod  18 . The surface features  1188  may be in the form of longitudinally spaced apart raised rings extending circumferentially around the diameter of push rod  18 . The rings may be circumferentially continuous or formed of discrete segments. In yet another alternative embodiment, the outer surface of the push rod  18  may comprise surface features in the form of bumps or protrusions, such as bumps or protrusions having the radial height characteristics set forth above. The bumps or protrusions may be randomly positioned on the surface of the rod  18 , or may be arranged in a predetermined pattern. 
     While the embodiments above contemplate the push rod  18  having a surface feature, it may be desirable in certain applications to include the surface feature on the inner surface of the cannula  12 .  FIG. 9  illustrates the cannula  12  having an inner surface  122 A having a surface feature effective for reducing binding/locking of the rod  18  within the cannula  12 . 
     Embodiments of the devices disclosed herein are generally designed to be disposed of after a single use, but could be designed to be used multiple times. After forming the marker, and inserting the marker into the deployer, the biopsy device can be sterilized. The device can be placed in a package, such as plastic or TYVEK bag. 
     The packaged biopsy device may then be placed in a field of radiation such as gamma radiation, x-rays, or high-energy electrons to sterilize the device and packaging. A device may also be sterilized using any other technique known in the art, including but not limited to beta or gamma radiation, ethylene oxide, or steam. 
     Having shown and described various embodiments of the present invention, further adaptations of the methods and systems described herein may be accomplished by appropriate modifications by one of ordinary skill in the art without departing from the scope of the present invention. Several of such potential modifications have been mentioned, and others will be apparent to those skilled in the art. Accordingly, the scope of the present invention should be considered in terms of the following claims and is understood not to be limited to the details of structure and operation shown and described in the specification and drawings.