Abstract:
A site marker device and marker are provided. The site marker device includes a housing and a distally extending delivery tube. A pusher rod is movably positioned within the delivery tube to eject a marker from the distal end thereof. An elongated tubular body is positioned about the delivery tube. An actuator is provided to provide two stage advancement. During the first stage, the delivery tube and the pusher rod are advanced through the distal end of the elongated tubular body. During the second stage of advancement, the pusher rod is advanced independently of the delivery tube to eject a marker from the distal end thereof. The marker is formed from a shape memory material and has a circular or hoop configuration in the relaxed state.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority as a continuation of PCT International Application No. PCT/US99/24867, filed Oct. 22, 1999, and U.S. provisional application Ser. Nos. 60/105,419, filed Oct. 23, 1998, and 60/101,801, filed Sep. 25, 1998, all of which are hereby incorporated by reference. 
    
    
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates generally to a marking device for identifying the location of a surgical site and, more specifically, a marking device which is insertable through a biopsy needle to position a marking hoop at a biopsy site. 
     2. Background of Related Art 
     Devices for marking lesions within the body are well known in the art. These devices generally include a cannula which is inserted into the body under local anesthesia to a position adjacent and/or in contact with the lesion. A wire marker is passed through the cannula and is anchored to the lesion so that the lesion is marked for subsequent surgical procedures such as excision or biopsy. After marking the lesion, the cannula is usually removed leaving the wire in place and extending from the body. 
     One problem associated with these devices is that the wire markers tend to dislodge and migrate during transport of the patient to undergo the subsequent surgical procedure. 
     U.S. Pat. No. 5,018,530 (“the &#39;530 patent”) discloses a wire needle assembly designed to overcome this problem. The &#39;530 patent attempts to solve the above-identified problem by providing a marker wire having a helically wound wire tip attached to a shaft which is inserted within the lumen of a cannula and then rotated into a lesion to anchor the marker within the lesion tissue. One disadvantage of the &#39;530 patent wire needle assembly is that the marker wire helix is too large in diameter to fit down the smaller biopsy cannulas. Moreover, some migration of the marker wire may still occur. 
     U.S. Pat. No. 5,221,269 (“the &#39;269 patent”) also discloses a device for marking the locating of a lesion. The device includes an introducer needle and a wire guide which is passed through a passageway in the introducer needle. The wire guide has a straight portion and a distal portion preformed into a resilient helical coil. When positioned in the passageway of the introducer needle, the preformed distal portion assumes an unwound configuration. The wire guide can be advanced distally from the introducer needle to mark the location of a lesion. 
     One problem associated with the device disclosed in the &#39;269 patent is that there is no structure disclosed for accurately advancing the wire guide into the lesion. Thus, if the wire guide is inserted too deeply into the lesion such that the straight portion extends through the lesion, migration may still occur. Moreover, because the adjacent coils of the helical wire guide are spaced, migration of the wire guide may still occur even if the wire guide is properly positioned. 
     Accordingly, a need exists for a site marking device for identifying the location of a surgical site or lesion which is capable of accurately positioning a marker which will not migrate adjacent the surgical site. 
     SUMMARY 
     In accordance with the present disclosure, a site marker assembly including a site marker device and a marker are provided. The site marker device includes a housing having a bore. A delivery tube is secured to a forward end of the housing and extends distally therefrom. A rod pusher is movably positioned within the delivery tube. An actuator including a plunger is movably positioned within the housing and is operably connected to the rod pusher. The plunger is movable from a first position to a second position to advance the rod pusher through the delivery tube and eject a marker from the distal end of the delivery tube. 
     In an alternate embodiment, an elongated tubular body is positioned about the delivery tube and the actuator further includes an inner housing movably positioned within the housing. The inner housing defines a bore in which the forward end of the plunger is positioned. The actuator is operably connected to the rod pusher and the delivery tube to provide two stage advancement. During the first stage of advancement, the rod pusher and the delivery tube are advanced through the distal end of the elongated tubular body. During the second stage of advancement, the rod pusher is advanced independently of the delivery tube to eject a marker from the delivery tube. 
     The marker is formed from a shape memory material such as tinel and has a circular or hoop configuration. The ends of the hoop are closely aligned or stacked to prevent migration of the hoop with respect to a lesion. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Various preferred embodiments of the site marker device are described herein with reference to the drawings wherein: 
     FIG. 1 is a side view of one embodiment of the presently disclosed site marking device in a retracted position; 
     FIG. 2 is a perspective view of the plunger of the site marker device shown in FIG. 1; 
     FIG. 3 is a perspective view of a housing half-section of the site marker device shown in FIG. 1; 
     FIG. 4 is a side view of the support tube of the site marker device shown in FIG. 1; 
     FIG. 5 is an exploded view of the indicated area of detail shown in FIG. 4; 
     FIG. 6 is a side view of the rod pusher of the site marker device shown in FIG. 1; 
     FIG. 7 is an exploded view of the indicated area of detail shown in FIG. 6; 
     FIG. 8 is a perspective view of the marker used in conjunction with the site marker device shown in FIG. 1; 
     FIG. 9 is a side view of the marker used in conjunction with the site marker device shown in FIG. 1; 
     FIG. 9A is an alternate embodiment of the marker shown in FIG. 9; 
     FIG. 10 is a side view of the site marking device shown in FIG. 1 in an advanced or actuated position; 
     FIG. 11 is a perspective view of another embodiment of the presently disclosed site marker device; 
     FIG. 12 is a perspective view with parts separated of the site marker device shown in FIG. 11; 
     FIG. 13 is a perspective view of the distal end of the site marker device shown in FIG. 11 in the retracted position; 
     FIG. 14 is a perspective view of the distal end of the site marker device shown in FIG. 11 in a partially advanced position; 
     FIG. 15 is a perspective view of the distal end of the site marker device shown in FIG. 11 in the advanced position; and 
     FIG. 16 is a perspective view of the site marker device shown in FIG. 11 in the advanced position. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Preferred embodiments of the presently disclosed site marker will now be described in detail with reference to the drawings, in which like reference numerals designate identical or corresponding elements in each of the several views. 
     One embodiment of the presently disclosed site marker will now be described with reference to FIGS. 1-10. FIG. 1 illustrates the site marker device shown generally as  10 . Briefly, site marker  10  includes a housing  12 , an elongated body  14 , and a plunger  16 . Elongated body  14  is secured to a forward end of housing  12  and extends distally therefrom. Plunger  16  has a forward end  16   a  which is slidably positioned within housing  12  and a proximal end  16   b  which extends outwardly from housing  12  (FIG.  2 ). 
     Referring to FIG. 2, plunger  16  has t-shaped body  18 , a large diameter head portion  20  and a small diameter plunger portion  22 . The t-shaped body includes four legs  23 , each leg being positioned perpendicular to each adjacent leg. One of the legs has a cutaway portion defining a shoulder  44  which will be discussed in further detail below. Head portion  20  is dimensioned to be engaged by the thumb of a surgeon, while plunger portion  22  is dimensioned and configured to be slidably positioned within housing  12 . Plunger portion  22  includes a slot  46  which is aligned with shoulder  44  formed in one of legs  23 . An abutment member  24  is positioned along the length of body  18  of plunger  16  to interact with four protrusions  26  formed on housing  12  (FIG. 3) and prevent separation of plunger  16  and housing  12 . As illustrated, abutment member  24  includes a cylindrical disc which is oriented perpendicular to the longitudinal axis of each of legs  23 . Alternately, the abutment member may have other configurations suitable to prevent separation of the plunger and housing. 
     Referring to FIG. 3, housing  12  is constructed from molded housing half-sections (only one is shown) and has a body  27  which defines a bore  28  having a proximal end  30  and a distal end  32 . An annular grasping collar  13  is positioned about body  27 . The four protrusions  26  are positioned at spaced locations about proximal end  30  of bore  28 . Each protrusion  26  is spaced from adjacent protrusions a distance slightly greater than the width of legs  23  of t-shaped body  18  such that each of the legs can be slidably positioned between the adjacent protrusions. Protrusions  26  prevent rotation of plunger  16  relative to housing  12 . Plunger portion  22  is dimensioned to be slidably positioned within bore  28  from a retracted position wherein abutment member  24  abuts protrusions  26  to an advanced position wherein plunger portion  22  engages the distal end of bore  28 , which is defined by a transverse wall  38 . Transverse wall  38  has a centrally located slot  36  formed therein dimensioned to permit passage of a rod pusher  40  (FIG.  6 ). 
     Referring to FIGS. 4 and 5, rod pusher  40  is formed from an elongated spring tempered material, such as metal. The proximal end of the rod pusher has a perpendicular bend  42 . Rod pusher  40  is dimensioned to be slidably positioned through slot  36  (FIG. 3) formed in wall  38  of housing  12  and slot  46  (FIG. 2) formed in plunger portion  22  of plunger  16 . Perpendicular bend  42  is configured to engage shoulder  44  of plunger  16  such that when the plunger is moved from the retracted to the advanced position, the rod pusher is moved from a retracted to an advanced position. 
     Referring to FIGS. 6 and 7, a small diameter spring tempered support tube  50  has a proximal end having an annular flange  52 . Annular flange  52  is dimensioned to be received in an annular slot  54  formed in the forward end of housing  12  (FIG.  3 ). When flange  52  is positioned within slot  54 , relative longitudinal movement of tube  50  in relation to housing  12  is prevented. Support tube  50  has a diameter slightly greater than rod pusher  40  and is positioned about rod pusher  40 . The close tolerance between tube  50  and rod pusher  40  prevents buckling of the rod pusher during movement between the retracted and advanced positions. 
     Referring to FIGS. 8 and 9, a marker  60  having a substantially circular or hoop configuration formed of shape memory material, such as tinel, is straightened and positioned in the distal end of support tube  50  at a location forward of the distal end of rod pusher  40 . During actuation of site marker  10 , plunger  16  is moved from the retracted to the advanced position by grasping collar  13  of housing  12  and pressing on head portion  20  of plunger  16 . As the plunger slides within bore  28 , rod pusher  40  is advanced distally within support tube  50 , such that the distal end of rod pusher  40  engages marker  60  and urges marker  60  out of the distal end of support tube  50 . As the marker exits the distal end of tube  50 , the marker returns to its normal circular or hoop configuration. 
     In an alternate embodiment illustrated in FIG. 9A, marker  60 ′ can include a substantially straight tail section  61 . Tail section  61  is of a length to extend from the body of a patient after marker  60  has been positioned adjacent a biopsy site. When using marker  60 ′ having a tail section  61 , rod pusher  40  must be shortened accordingly. 
     FIGS. 11-16 illustrate an alternate embodiment of the site marker device shown generally as  100 . FIG. 11 illustrates a perspective view of site marker  100 . Briefly, site marker device  100  includes a housing  112  having a guide tube  114  extending distally from a forward end thereof. A plunger  116  having a cylindrical cover  118  is slidably positioned within a cylindrical bore (not shown) formed within housing  112  and includes a proximal end  112   a  extending from a rearward end of housing  112 . A coupler  120  is secured to the distal end of guide tube  114  using known techniques, e.g., crimping, adhesives, welding, etc. Coupler  120  is adapted to receive a diverter  122  which will be discussed in further detail below. It is also envisioned that site marker device  100  be used without coupler  120  and diverter  122 . 
     Referring to FIG. 12, plunger  116  includes a large diameter head portion  124  dimensioned to be engaged by the thumb of a surgeon and a plunger portion  126  dimensioned to be positioned within housing  112 . The plunger is slidable within housing  112  from a retracted position to an advanced position. A biasing member  130 , which is preferably a coil spring, is positioned between head portion  124  and the end of the bore defined within housing  112  to urge the plunger to the retracted position. Plunger  116  includes an annular rib  128  which will be discussed in further detail below. A rod pusher  132  is secured to the plunger portion  126  of plunger  116  using known techniques, e.g., pins, threads, crimping, annular flange, etc. Rod pusher  132  is formed from a small diameter spring tempered material such as metal and is movable from a retracted to an advanced position in response to movement of the plunger from the advanced to the retracted position. Alternately, other resilient materials may be used to form the rod pusher. 
     An inner housing  134 , which is preferably formed from molded housing half-sections  134   a  and  134   b , is positioned about plunger  116  and slidably positioned within the bore (not shown) defined within housing  112 . Inner housing  134  defines a second bore  136  within which plunger portion  126  of plunger  116  is positioned. Bore  136  of inner housing  134  includes a forward wall  137  and a pair of detents  138  formed on opposite walls thereof. Detents  138  are positioned to engage annular rib  128  on plunger  116  to prevent plunger portion  126  from moving into engagement with wall  137  of bore  136  until after a predetermined force sufficient to move rib  128  over detents  138  has been applied to plunger  116 . Thus, when the plunger  116  is in the retracted position, plunger portion  126  of plunger  116  is spaced from wall  137  of bore  136  a predetermined distance. 
     A delivery tube  140  is secured to a forward end of inner housing  134  using known techniques, e.g., crimping, threads, etc. Preferably, the proximal end of delivery tube  140  includes an annular flange such as shown in FIG. 5 which is received in an annular slot formed in the distal end of inner housing  134  to secure the delivery tube to the inner housing. The delivery tube  140  is preferably formed from spring tempered material such as metal and has an inner diameter dimensioned to permit rod pusher  132  to slide therein. The inner diameter of delivery tube  140  is only slightly larger than the outer diameter of rod pusher  132  to prevent buckling of the rod pusher  132  as it is moved from the retracted to the advanced position. 
     As discussed above, coupler  120  and a diverter  122  are secured to the distal end of guide tube  114 . As illustrated in FIG. 13, diverter  122  has a curved channel  150  extending therethrough. In the retracted position of plunger  116 , the distal end of delivery tube  140  is positioned partially within curved channel  150 . 
     Marker  160  is positioned in the distal end of delivery tube  140  at a location forward of the distal end of rod pusher  132 . Marker  160  is formed from shape memory material, such as tinel, and has a relaxed substantially circular or hoop configuration. Alternately, a marker having a tail section, such as illustrated in FIG. 8A may also be used. 
     Referring to FIG. 14, during the initial movement of plunger  116  from the retracted position towards the advanced position, plunger  116  advances inner housing  134  distally within the housing bore (not shown) formed within housing  112 . Plunger  116  and inner housing  134  will move together until the forward end of inner housing  134  abuts against the base of the bore defined by housing  112 . At this point, the delivery tube  140  has been advanced through curved channel  150  formed in diverter  112  and is angled outwardly and spaced from the distal end of guide tube  114 . Rod pusher  132  has not yet been moved relative to delivery tube  140  and marker  160  is still positioned in the distal end of delivery tube  140 . 
     Referring to FIG. 14, when a predetermined force sufficient to advance annular rib  128  over detents  138  is applied to plunger  116 , plunger  116  moves within bore  136  of inner housing  134  to move rod pusher  132  within delivery tube  140 . The distal end of rod pusher  132  engages marker  160  and urges marker  160  out of the distal end of delivery tube  140 . As marker  160  is ejected from delivery tube  140 , marker  160  will return to the relaxed state in which the marker has a substantially circular or hoop configuration. See FIGS. 15 and 16. 
     Site marker device  100  may be used in conjunction with the biopsy apparatus and method disclosed in U.S. patent application Ser. No. 09/040,244 filed Feb. 20, 1998, currently pending (&#39;244 application) which is incorporated herein by reference. 
     It will be understood that various modifications may be made to the embodiments disclosed herein. For example, the actuator need not be a plunger-type actuator but rather may be a trigger-type actuator or other known actuation mechanism. Moreover, the site marker device can be constructed from a variety of materials having the requisite strength and resiliency characteristics including plastics and metals. Therefore, the above description should not be construed as limiting, but merely as exemplifications of preferred embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.