Patent Abstract:
A biopsy marking apparatus for placing a radiopaque marker at the location of a percutaneous biopsy. The biopsy marking apparatus comprises an introducer in combination with a radiopaque marker. The introducer ejects the radiopaque marker at the location of the biopsy. The introducer is configured to completely eject the radiopaque marker and prevent it from being subsequently drawn into the introducer as the introducer is removed from the biopsied tissue mass. The radiopaque marker has enhanced radiopaque characteristics and enhanced non-migration characteristics.

Full Description:
RELATED APPLICATION 
     This application is a continuation of U.S. patent application Ser. No. 10/421,517, filed Apr. 23, 2003 now U.S. Pat. No. 7,569,065, which is a divisional of U.S. patent application Ser. No. 09/596,160, filed Jun. 16, 2000 now U.S. Pat. No. 6,575,991, which claims the priority of U.S. Provisional Patent Application Ser. No. 60/139,580, filed Jun. 17, 1999. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to an apparatus for the percutaneous positioning of a radiopaque marker for identifying the location of a lesion in a stereotactic biopsy procedure. More particularly, the invention relates to an introducer having a hollow cannula in combination with a movable stylet and a radiopaque marker disposed within the cannula and ejected from it by movement of the stylet. 
     2. Related Art 
     Tissue biopsies are commonly performed on many areas and organs of the body where it is desirable to ascertain whether or not the biopsied tissue is cancerous. Often, a lesion or other tissue to be biopsied is identified through use of an imaging technique such as a computerized axial tomography (CAT) scan, ultrasonography, and mammography. 
     One problem commonly encountered, especially in breast biopsies, is that the lesion is so small that the biopsy reduces its size to the extent that it is no longer visible by the imaging method employed. In such circumstances, it is desirable to place a radiopaque marker at the site of the biopsy to enable the medical practitioner subsequently to locate the lesion quickly and accurately in the event complete removal of the affected tissue is indicated. This problem is currently met by placing a radiopaque marker at the biopsy area by means of a cannula or similar device housing the marker. 
     More particularly, one of the markers heretofore in use is a staple-type clip. The clip is introduced through a large-diameter cannula, specifically one of 11 gauge. 
     Some practitioners employ an embolization coil as a marker. This requires them to find a cannula or hollow needle of a size to receive the coil and some means to force the coil through the needle, all the while trying to keep these components together and sterile. 
     Prior devices for marking a biopsy area have several other disadvantages. A significant disadvantage is that the marker is not always completely ejected from the cannula or can be drawn back into or toward the cannula by the vacuum created upon the withdrawal of the cannula, which results in the marker being moved from the intended site, leading to inaccurate identification of the location of the biopsy area. A second major disadvantage is that current markers have a tendency to migrate within the tissue, also causing error in determining the biopsy location. 
     SUMMARY OF THE INVENTION 
     The present invention provides a biopsy marking apparatus for the percutaneous placement of a marker at a biopsy site in a tissue mass to facilitate subsequent determination of the location of the biopsy site. The biopsy marking apparatus comprises an introducer having a handle to be grasped by a user, a cannula, a stylet, and a radiopaque marker. The cannula has a proximal end mounted to the handle and a distal end defining an insertion tip. The stylet is slidably received within the cannula for movement between a ready position in which a distal end of the stylet is spaced inwardly from the cannula tip to form a marker recess between the distal end of the stylet and the cannula tip, and an extended position in which the distal end of the stylet extends at least to the cannula tip to effectively fill the marker recess. 
     A plunger is movably mounted to the handle and operably engages the stylet, the plunger being movable between a first position and a second position for moving the stylet between the ready position and the extended position. 
     A latch is provided for fixing the stylet in the extended position to prevent retraction of the stylet from that position. 
     A radiopaque marker is disposed within the marker recess, whereby, when the plunger is moved between the first and second positions, the stylet is moved from the ready to the extended position to eject the radiopaque marker from the marker recess, and the latch fixes the stylet in the extended position to prevent the return of the marker to the marker recess. 
     The latch preferably comprises a detent on either the plunger or the handle and a catch on the other, the catch being receivable within the detent as the plunger is moved from the first to the second position. 
     In another aspect, the invention also provides a radiopaque marker having a marker body and an anchor extending away from the body for fixing the location of the radiopaque marker in a tissue mass by the tissue mass prolapsing about the anchor. Preferably, the body has an interior hollow portion forming an air trap to enhance the ultrasound characteristic of the radiopaque marker. 
     Other features and advantages of the invention will be apparent from the ensuing description in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIG. 1  is a plan view of an introducer used to place a radiopaque marker at a biopsy location in accordance with the invention; 
         FIG. 2  is an enlarged sectional view of the area II of  FIG. 1 , illustrating the position of a radiopaque marker within the introducer prior to ejection; 
         FIG. 3  is an enlarged sectional view of the area III of  FIG. 1 , illustrating the arrangement of a handle, a plunger, and a stylet of the introducer; 
         FIG. 4  is a sectional view taken along line  4 - 4  of  FIG. 1  and illustrating the introducer in a ready condition; 
         FIG. 5  is a sectional view taken along line  4 - 4  of  FIG. 1  and illustrating the introducer in a discharged condition; 
         FIG. 6  is an enlarged view of a first embodiment of a radiopaque marker according to the invention; 
         FIG. 7  is an enlarged view of a second embodiment of a radiopaque marker according to the invention; 
         FIG. 8  is an enlarged view of a third embodiment of a radiopaque marker according to the invention; 
         FIG. 9  is an enlarged view of a fourth embodiment of a radiopaque marker according to the invention; 
         FIG. 10  is a partially broken away perspective view, greatly enlarged, of a fifth embodiment of a radiopaque marker according to the invention; 
         FIG. 11  is a plan view of the radiopaque marker of  FIG. 10 ; 
         FIG. 12  is a greatly enlarged view of a sixth embodiment of a radiopaque marker according to the invention; 
         FIG. 13  is a greatly enlarged view of a seventh embodiment of a radiopaque marker according to the invention; 
         FIG. 14  is a greatly enlarged view of an eighth embodiment of a radiopaque marker according to the invention; and 
         FIG. 15  is a greatly enlarged view of a ninth embodiment of a radiopaque marker according to the invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1 to 4  illustrate a biopsy marking apparatus  10  according to the invention, which is capable of the percutaneous placement of a radiopaque marker at the location of a tissue biopsy. The biopsy marking apparatus  10  comprises an introducer  12  and a radiopaque marker  14  ( FIG. 2 ) contained within the introducer  12 . The introducer  12  includes a handle  16  having a hollow interior  18 . The handle  16  comprises a grip portion  20  from which extends a tapered nose portion  22 . The grip portion  20  defines a rear opening  24  that provides access to the hollow interior  18 . A pair of detents  26  are formed in the grip portion  20  near the rear opening  24 . Channels  28  are formed on the interior surface of the grip portion  20  and extend from the rear opening  24  to the detents  26 . 
     The nose portion  22  comprises a guide passage  30  extending from the tip of the nose portion  22  to the hollow interior  18  of the handle  16 . The guide passage  30  decreases in diameter inwardly from the tip of the nose portion to form a cannula seat  32 . Alternatively, the diameter of the guide passage  30  may be substantially equal to or slightly smaller than the outer diameter of a cannula  34 , which in any case is press-fit within the cannula seat  32 . As is customary, the cannula is formed with a hollow interior  36  and a sharpened tip  38 . 
     A stylet  40  comprising a shaft  42  and a base  44  is received within the hollow interior  18  of the handle  16  in a manner such that the shaft  42  extends through the guide passage  30  and into the cannula interior  36  and the stylet base lies within the hollow interior  18 . 
     A plunger  50  comprises a cylindrical body  52  from which extend a pair of catches  54  at diametrically opposed positions. The cylindrical body  52  is sized so that it is slidably received within the rear opening  24  of the handle  16 , where it is so oriented with respect to the handle that the catches  54  are aligned with the guide channels  28 . 
     It will be recognized that the foregoing construction provides a biopsy marking apparatus which may be preassembled as a unit and prepackaged, all under sterile conditions, thereby affording the practitioner substantially greater convenience and reliability. Such a construction also permits use of a narrower cannula, which may be of 14 gauge or smaller. 
     In operation, the introducer  12  begins in the ready condition shown in  FIG. 4 . In this condition, the stylet shaft is received within the cannula but does not extend to the cannula tip  38 , thereby forming a marker recess  46  within the cannula  34 , the radiopaque marker  14  is disposed within the marker recess  46 , and the plunger  50  is in a position relative to the handle  20  in which the catches are outside the handle; that is, they are not received within the detents  26 . However, the plunger  50  is so oriented with respect to the handle that the catches  54  are aligned with the guide channels  28 . 
     With the introducer in the ready condition, the cannula is positioned so that its tip is at or near the location of a tissue mass where a biopsy has been taken. Preferably, the cannula tip is positioned by using imaging systems. The cannula tip  38  can be designed for enhanced visibility using common imaging systems, such as CAT scan, ultrasonography and mammography. Suitable cannula tips are disclosed in U.S. Pat. No. 5,490,521, issued Feb. 13, 1996 to R. E. Davis and G. L. McLellan, which is incorporated by reference. Ultrasound enhancement technology is also disclosed in U.S. Pat. No. 4,401,124, issued Aug. 30, 1983 to J. F. Guess, D. R. Dietz, and C. F. Hottinger; and U.S. Pat. No. 4,582,061, issued Apr. 15, 1986 to F. J. Fry. 
     Once the cannula is positioned at the desired location, the plunger  50  is moved from its first or ready condition as illustrated in  FIGS. 1 to 4  to a second or discharged condition in which the catches  54  are received within the detents  26  to lock the plunger  50  in the discharged condition and the stylet shaft extends beyond the cannula tip  38 . The catches  50  and detents combine to function as a latch for locking the plunger in the discharged condition. As the plunger  50  is moved from the ready condition to the discharged condition, the plunger  50  drives the stylet base  44  forward to advance the stylet shaft  42  within the cannula interior  36 . As the stylet shaft  42  is advanced, the radiopaque marker  14  is ejected from the marker recess  46  through the cannula tip  38  and into the tissue at the biopsy location. 
     It is preferred that the stylet shaft  42  be sized in a manner such that when the plunger  50  is in the discharged condition the stylet shaft  42  extends beyond the cannula tip  38  to ensure the complete ejection of the radiopaque marker  14  from the marker recess  46 . The extension of the stylet shaft  42  beyond the cannula tip  38  also prevents the radiopaque marker  14  from being drawn back into the marker recess upon the removal of the introducer  12  from the tissue mass, which can occur as the tissue mass collapses and is drawn towards and into the cannula by the resilient nature of the tissue mass and the creation of a vacuum by the cannula as it is withdrawn from the tissue. 
     The rate at which the plunger  50  is moved from the ready condition to the discharged condition is preferably manually controlled by the user to control the rate at which the marker  14  is ejected into the tissue mass. Manual control of the ejection rate of the radiopaque marker provides the user with the ability to adjust the position of the cannula tip as the marker is being ejected and thereby permits additional control of the final location of the marker within the tissue mass. In other words, “on-the-fly” adjustment of the cannula tip during positioning of the marker  14  enables a more accurate placement of the marker. 
     The biopsy marking apparatus  12  may be placed in a safety condition (not shown) before packaging or use by rotationally orienting the plunger  50  with respect to the handle  16  so that the catches  54  are out of alignment with the guide channels  28 , whereby the plunger cannot be depressed or advanced within the handle. It will be apparent that the marking apparatus can be placed in the ready condition previously described simply by rotating the plunger relative to the handle until the catches  54  are aligned with the guide channels  28 . 
     It will also be apparent that the biopsy marking apparatus  10  may incorporate or be fitted with any one of several known trigger devices, some of them spring-loaded, for advancement of the plunger  50 . Such a trigger device is disclosed, for example, in U.S. Pat. No. 5,125,413, issued Jun. 30, 1992 to G. W. Baran. 
     It should be noted that as a variation of the foregoing procedure the cannula employed during the biopsy procedure might be left in place with its tip remaining at the site of the lesion. The introducer  12  of the present invention would then be directed to the site through the biopsy cannula or, alternatively, the marker  14  of the present invention would be introduced to the biopsy cannula and ejected from its tip into the tissue mass by fitting the biopsy cannula to the introducer  12  in place of the cannula  34 . 
     The radiopaque marker  14  used in combination with the introducer  12  to mark the location of the tissue biopsy should not only be readily visible using contemporary imaging techniques but it should not migrate within the tissue from the position in which it is initially placed.  FIGS. 6 to 15  disclose various embodiments of radiopaque markers  14  that are highly visible using contemporary imaging techniques and are resistant to migration in the tissue. 
       FIG. 6  illustrates a first embodiment  60  of a radiopaque marker comprising a coil spring  62  from which extend radiopaque fibers  64 . The coil spring  62  is preferably made from platinum or any other material not rejected by the body. The coil spring  62  is wound to effectively form a hollow interior comprising one or more air pockets, which are highly visible using contemporary ultrasound imaging techniques. The radiopaque fibers  64  are preferably made from Dacron, which is also highly visible using current imaging techniques. 
     The radiopaque marker  60  is highly visible using any of the commonly employed contemporary imagining techniques because of the combination of reflective surfaces formed by the coils, the hollow interior and the air pockets of the coil spring  62 , as well as the radiopaque fibers  64 . 
     The coil spring  62  is pre-shaped prior to being loaded into the marker recess  46  so that it tends to form a circular shape as shown in  FIG. 6  after it is ejected from the marker recess  46 . The circular shape tends to resist migration within the tissue. 
       FIG. 7  illustrates a second embodiment  70  of a radiopaque marker having a star-burst configuration comprising a core  72  with multiple fingers  74  extending from the core. 
       FIG. 8  illustrates a third embodiment  80  of a radiopaque marker that is similar to the star-burst marker  70  in that it comprises a core  82  from which extend three fingers  84 . Each of the fingers includes radiopaque fibers  86 , which are preferably made from Dacron or a similar material. 
       FIG. 9  illustrates a fourth embodiment  90  of a radiopaque marker having a generally Y-shaped configuration comprising an arm  92  from which extend diverging fingers  94 . The arm and fingers  92 ,  94  are preferably made from a suitable resilient metal such that the fingers can be compressed towards each other and the entire radiopaque marker  90  stored within the marker recess  46  of the cannula. Upon ejection of the marker  90  from the marker recess  46  into the tissue mass, the fingers  94  will spring outwardly to provide the marker  90  with an effectively greater cross-sectional area. 
     In addition to providing the marker  90  with an effectively greater cross-sectional area, the tips of the fingers  94 , together with the free end of the arm  92 , effectively form points of contact with the surrounding tissue mass that help to anchor the marker  90  in its release condition to prevent migration through the tissue mass. 
       FIG. 10  illustrates a fifth embodiment  100  of a radiopaque marker having a wire-form body in a horseshoe-like configuration comprising a rounded bight portion  102  from which extend inwardly tapering legs  104 , each of which terminate in curved tips  106 . The entire marker  100  preferably has a circular cross section defining a hollow interior  108 . The hollow interior provides for the trapping of air within the marker  100  to improve the ultrasound characteristics of the marker  100 . 
     The curved bight portion  102  and legs  104  preferably lie in a common plane. However, the tips  106  extend away from the legs  104  and out of the common plane so that the tips  106  will better function as anchors for the tissue that prolapses about the tips  106  once the marker  100  is ejected from the marker recess  46  and the introducer  12  is withdrawn from the tissue mass. 
       FIG. 12  illustrates a sixth embodiment  110  of a radiopaque marker that is similar to the horseshoe-like fifth embodiment marker  100  in that it comprises a bight portion  112  from which extend legs  114 , which terminate in tips  116 . The legs  114  of the marker  110  are crossed relative to each other, unlike the legs of the marker  100 , providing the marker  110  with an effectively larger cross-sectional diameter. The tips  116  are oriented at approximately 90° relative to the legs  114  to form anchors. The marker  110  also has a hollow interior  118  for enhanced radiopaque characteristics. 
     Though, as illustrated in  FIG. 12 , the tips  116  of the marker  110  are oriented at approximately 90° with respect to the legs  114 , it is within the scope of the invention for the tips  116  to extend at substantially any angle with respect to the legs  114 . The tips  116  also need not extend away from the legs in the same direction. For example, the tips  116  could extend in opposite directions from the legs  114 . 
       FIG. 13  illustrates a seventh embodiment  120  of a radiopaque marker having a generally helical configuration comprising multiple coils  122  of continuously decreasing radius. The helical marker  120  is preferably made from a radiopaque material and has a hollow interior  124  to enhance its radiopaque characteristics. The decreasing radius of the coils  122  provides the marker  120  with multiple anchor points created by the change in the effective cross-sectional diameter along the axis of the helix. In other words, since the effective cross-sectional diameter of each coil is different from the next and each coil is effectively spaced from adjacent coils at the same diametric location on the helix, the tissue surrounding the marker  120  can prolapse between the spaced coils and each coil effectively provides an anchor point against the tissue to hold the marker  120  in position and prevent its migration through the tissue mass. 
       FIG. 14  illustrates an eighth embodiment  130  of a radiopaque marker comprising a cylindrical body  132  in which are formed a series of axially spaced circumferential grooves  134 . The spaced grooves  134  form a series of ridges  136  therebetween on the outer surface of the cylindrical body  132 . The cylindrical body  132  preferably includes a hollow interior  138 . 
     The alternating and spaced ridges  136  and grooves  134  provide the marker  130  with a repeating diameter change along the longitudinal axis of the cylindrical body  132 . As with the helical marker  120 , the grooves  134  between the ridges  136  provide an area in which the tissue surrounding the marker  130  can prolapse thereby enveloping the ridges  136 , which function as anchors for preventing the migration of the marker  130  in the tissue mass. 
       FIG. 15  illustrates a ninth embodiment  140  of a radiopaque marker comprising a cylindrical body  142  having an axial series of circumferential grooves  144  whose intersections with adjacent grooves form ridges  146 . The cylindrical body  142  preferably includes a hollow interior  148 . An anchor  150  extends from the cylindrical body  142 . The anchor  150  comprises a plate  152  connected to the cylindrical body  142  by a wire  154 . 
     The grooves  144  and ridges  146  of the maker  140  provide anchors in the same manner as the grooves  134  and ridges  136  of the marker  130 . The anchor  150  further enhances the non-migrating characteristics of the marker  140  by permitting a large portion of the surrounding tissue mass to prolapse between the plate  150  and the cylindrical body  142 . 
     The fifth through the ninth embodiments all preferably have a wire-form body. The various wire-form body shapes can be formed by stamping the shape from metal stock or the bending of a wire. 
     It should be noted that virtually all of the embodiments of the radiopaque marker described as being hollow can be made without a hollow interior. Similarly, those without a hollow interior can be made with a hollow interior. The hollow interior improves the ultrasound characteristics of the particular marker beyond the inherent radiopaque and ultrasound characteristics attributable to the marker shape and material. In practice, the use of the hollow interior is limited more by manufacturing and cost considerations rather than by performance. 
     Also, the shape of each marker can be altered to improve or enhance its non-migrating characteristics by adding an express anchor such as that disclosed in connection with the marker  140  or by modifying the marker to provide more anchor points as may be compatible with the basic configuration of the marker. 
     The combination of the enhanced radiopaque characteristics of the markers and the enhanced non-migrating features result in markers that are superior in use for identifying biopsy location after completion of the biopsy. The ability to accurately locate the biopsy site greatly reduces the amount of tissue that must be removed in a subsequent surgical procedure if the biopsy is cancerous. Additionally, the marker further enhances the ability to use percutaneous methods for removing the entire lesion, reducing the trauma associated with more radical surgical techniques. 
     The radiopaque markers described and illustrated herein are smaller than the staple-type clip and embolization coil used heretofore, thereby permitting a cannula of 14 gauge or less. 
     While the invention has been specifically described in connection with certain specific embodiments thereof, it is to be understood that this is by way of illustration and not of limitation, and the scope of the appended claims should be construed as broadly as the prior art will permit. 
     
       
         
               
             
               
               
             
           
               
                   
               
               
                 PARTS LIST 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 10 
                 biopsy marking apparatus 
               
               
                 12 
                 introducer 
               
               
                 14 
                 radiopaque marker 
               
               
                 16 
                 handle 
               
               
                 18 
                 hollow interior 
               
               
                 20 
                 grip portion 
               
               
                 22 
                 nose portion 
               
               
                 24 
                 rear opening 
               
               
                 26 
                 detents 
               
               
                 28 
                 guide channels 
               
               
                 30 
                 guide passage 
               
               
                 32 
                 cannula seat 
               
               
                 34 
                 cannula 
               
               
                 36 
                 cannula interior 
               
               
                 38 
                 cannula pointed tip 
               
               
                 40 
                 stylet 
               
               
                 42 
                 stylet shaft 
               
               
                 44 
                 stylet base 
               
               
                 46 
                 marker recess 
               
               
                 48 
               
               
                 50 
                 plunger 
               
               
                 52 
                 cylindrical body 
               
               
                 54 
                 catch 
               
               
                 56 
               
               
                 58 
               
               
                 60 
                 radiopaque marker 
               
               
                 62 
                 coil spring 
               
               
                 64 
                 radiopaque fibers 
               
               
                 66 
               
               
                 68 
               
               
                 70 
                 second embodiment radiopaque marker 
               
               
                 72 
                 core 
               
               
                 74 
                 markers 
               
               
                 76 
               
               
                 78 
               
               
                 80 
                 third embodiment radiopaque maker 
               
               
                 82 
                 core 
               
               
                 84 
                 fingers 
               
               
                 86 
               
               
                 88 
               
               
                 90 
                 fourth embodiment radiopaque marker 
               
               
                 92 
                 arm 
               
               
                 94 
                 fingers 
               
               
                 96 
               
               
                 98 
               
               
                 100 
                 fifth embodiment radiopaque marker 
               
               
                 102 
                 curved bight portion 
               
               
                 104 
                 legs 
               
               
                 106 
                 tips 
               
               
                 108 
               
               
                 110 
                 sixth embodiment radiopaque marker 
               
               
                 112 
                 curved bight portion 
               
               
                 114 
                 legs 
               
               
                 116 
                 tips 
               
               
                 118 
                 hollow interior 
               
               
                 120 
                 seventh embodiment radiopaque marker 
               
               
                 122 
                 coil 
               
               
                 124 
               
               
                 126 
               
               
                 128 
               
               
                 130 
                 eighth embodiment radiopaque marker 
               
               
                 132 
                 cylindrical body 
               
               
                 134 
                 grooves 
               
               
                 136 
                 ridges 
               
               
                 138 
                 hollow interior 
               
               
                 140 
                 ninth embodiment radiopaque marker 
               
               
                 142 
                 cylindrical body 
               
               
                 144 
                 grooves 
               
               
                 146 
                 ridges 
               
               
                 148 
                 hollow interior 
               
               
                 150 
                 anchor 
               
               
                 152 
                 plate

Technology Classification (CPC): 0