Abstract:
A biopsy device is disclosed that comprises a cutting element mounted to a handpiece and a vacuum chamber. The cutting element comprises a stylet assembly and an outer cannula assembly. The stylet assembly includes a stylet that includes an open proximal end and a tissue opening at a distal end thereof. The distal end of the stylet is blunt-shaped. The tissue receiving opening is in communication with a lumen extending through the stylet. The outer cannula assembly includes an outer cannula that is slidably mounted over the stylet and has an open distal end with a cutting edge formed thereon. The vacuum chamber is in communication with the lumen of the stylet. The stylet is selectively advanced distally outwardly with respect to outer cannula to expose the tissue opening to targeted tissue. The outer cannula is selectively advanced over the tissue opening to sever tissue, while vacuum is generated in the vacuum chamber and delivered to the tissue opening through the lumen. The vacuum causes tissue to be drawn into and maintained in the tissue opening while the outer cannula severs tissue to obtain a biopsy core.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation-in-part of U.S. Ser. No. 12/039,364 filed Feb. 28, 2008, which claims priority to U.S. Provisional patent application Ser. No. 60/892,174, filed on Feb. 28, 2007 and which is a Continuation-in-part of U.S. Ser. No. 11/389,274 filed on Mar. 24, 2006, which is a Continuation-in-Part of U.S. Serial No. 10/964,959 filed Oct. 14, 2004 now U.S. Pat. No. 7,390,306 which claims priority to U.S. provisional patent application Ser. No. 60/510,866 filed on Oct. 14, 2003, the disclosures of which are incorporated herein by reference in their entireties. This application also claims benefit of U.S. provisional patent application Ser. No. 60,970,770 filed on Sep. 7, 2007, the contents of which is also incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure generally relates to the field of tissue sampling and harvesting. More specifically, the disclosure relates to biopsy needle sets and devices. 
     BACKGROUND 
     In the practice of diagnostic medicine, it is often necessary or desirable to perform a biopsy, or to sample selected tissue from a patient for medical evaluation. Cytological and histological studies of the biopsy sample can then be performed as an aid to the diagnosis and treatment of disease. Biopsies can be useful in diagnosing and treating various forms of cancer, as well as other diseases in which a localized area of affected tissue can be identified. 
     Biopsies are routinely performed on tissue using a needle set, which typically includes a stylet with a pointed tip and a notch defined near its distal end. The stylet is slidably disposed within a cannula so that the notch can be alternately exposed or covered. Such needle sets are used with or incorporated in various forms of biopsy devices, such as single action or double action biopsy devices. 
     More specifically, one known exemplary single action biopsy device includes a hollow needle. A stylet is slidingly disposed within the hollow needle lumen and is moveable relative to needle. A distal end of the stylet is provided with a tissue cutting-point and a tissue opening is positioned adjacent to the distal end for receiving tissue samples. The stylet is slidable relative to needle between a first or retracted position and a second or extended position. 
     In the first position, the stylet is retracted within the needle such that the needle covers the tissue opening. In the second position, the distal end of the stylet is extended away from the needle to expose the tissue opening to tissues at the biopsy site. 
     During a biopsy procedure, the device will be positioned within a cavity at a targeted site for the biopsy. The stylet is momentarily driven into the tissue and tissue then prolapses into the tissue opening. The needle is then advanced along the stylet to cover the tissue opening. This forward movement of needle severs the prolapsed tissue to obtain a tissue sample, which becomes trapped in tissue opening of the stylet. With the needle  22  blocking the opening of tissue opening, the biopsy device is then withdrawn from the target site, carrying the sample within tissue opening. To collect the biopsy sample, the needle is once again retracted to expose tissue opening of the stylet. The procedure may be repeated several times until satisfactory samples have been obtained. 
     While single and double action biopsy devices are widely used, a basic problem remains in the field of biopsy, which is the need to obtain a sufficient amount of sample tissue. One potential cause of the problem is that as the needle passes over the tissue opening, the needle has a tendency to push the tissue away from the tissue opening. This results in samples that are inferior in quality or too small, which precludes the pathologist from conclusively determining whether disease is present, and if so, to what extent it has progressed. The pathologist must then issue an inconclusive diagnostic report. This causes the physician to recall the patient and attempt another needle biopsy, or in some situations, the patient is scheduled for a more invasive, traumatic and expensive procedure such as an open surgical biopsy. 
     The challenge has been to consistently obtain sufficient tissue volume and quality tissue cores, regardless of tissue type, to meet the needs of the pathologist so that a conclusive diagnosis can be achieved. 
     SUMMARY 
     A biopsy device is disclosed that comprises a cutting element mounted to a handpiece and a vacuum chamber. The cutting element comprises a stylet assembly and an outer cannula assembly. The stylet assembly includes a stylet that includes an open proximal end and a tissue opening at a distal end thereof. The tissue receiving opening is in communication with a lumen extending through the stylet. The outer cannula assembly includes an outer cannula that is slidably mounted over the stylet and has an open distal end with a cutting edge formed thereon. The vacuum chamber is in communication with the lumen of the stylet. The stylet is selectively advanced distally outwardly with respect to outer cannula to expose the tissue opening to targeted tissue. The outer cannula is selectively advanced over the tissue opening to sever tissue, while vacuum is generated in the vacuum chamber and delivered to the tissue opening through the lumen. The vacuum causes tissue to be drawn into and maintained in the tissue opening while the outer cannula severs tissue to obtain a biopsy core. A method of using the biopsy device is also disclosed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the disclosure will now be described, by way of example, with reference to the accompanying drawings, wherein: 
         FIG. 1  is a perspective view of a biopsy device assembly, including a biopsy device and an introducer assembly. 
         FIG. 2  is an exploded view of the biopsy device of  FIG. 1 . 
         FIG. 3  is a perspective view of the underside of a pickup carriage assembly for use with the biopsy device. 
         FIG. 4  is an exploded view of the pickup carriage assembly, illustrating a moveable cam member and a spring member that attaches to a top surface of the pickup carriage. 
         FIG. 5  is a perspective view of the underside of the pickup carriage. 
         FIG. 6  is a perspective view of the moveable cam member. 
         FIG. 7  is a perspective view of a stylet and vacuum hub assembly. 
         FIG. 8  is a perspective view of the stylet and vacuum hub assembly of  FIG. 7  with a vacuum chamber enclosure member attached and a cutting cannula assembly attached. 
         FIG. 9  is a perspective view of the cutting cannula assembly of  FIG. 8 . 
         FIG. 10  is a perspective view of one embodiment of a resilient bridge member. 
         FIG. 11  is a partial cut-away perspective view of the biopsy device with the introducer assembly attached to the front portion thereof. 
         FIG. 12  is a partial cut-away side elevational view of the biopsy device after a release latch has been activated and an actuating lever has been released (note that the bridge member of  FIG. 10  has been omitted for clarity). 
         FIG. 13  is a side elevational view of the biopsy device after the actuating lever has been depressed a first time, thereby retracting a piston. 
         FIG. 14  is a side elevational view of the biopsy device after the actuating lever has been depressed a second time, thereby retracting the cutting cannula. 
         FIG. 15  is a side elevational view of the biopsy device after the actuating lever has been depressed a third time, thereby retracting the stylet into the cutting cannula. 
         FIG. 16  is a side elevational view of the biopsy device after the stylet has been fired away from a housing of the biopsy device. 
         FIG. 17  is a side elevational view of the biopsy device after the cutting cannula has been fired forward over the tissue receiving opening of the stylet. 
         FIG. 18  is a side elevational view of the biopsy device after the release latch has been released (note that the bridge member of  FIG. 10  has been omitted for clarity). 
         FIG. 19  is a side elevational view of the biopsy device after the vacuum chamber has been retracted. 
         FIG. 20  is a side elevational view of the biopsy device after the cutting cannula has been retracted so as to expose the tissue receiving opening to permit tissue cores to be removed from the tissue receiving opening. 
         FIG. 21A-21D  are various views of a valve member. 
         FIG. 22  is a partial cut-away side elevational view of an alternative embodiment of a biopsy device, after the actuating lever has been depressed a second time, thereby retracting the cutting cannula; 
         FIG. 23  is a side elevational view of the biopsy device in  FIG. 22 , after the actuating lever has been depressed a third time, thereby retracting the distal end inner cannula, within the cutting cannula. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawings, preferred illustrative embodiments are shown in detail. Although the drawings represent some embodiments, the drawings are not necessarily to scale and certain features may be exaggerated, removed, or partially sectioned to better illustrate and explain the present disclosure. Further, the embodiments set forth herein are not intended to be exhaustive or otherwise limit or restrict the claims to the precise forms and configurations shown in the drawings and disclosed in the following detailed description. 
     Referring to  FIG. 1 , a perspective view of an exemplary biopsy device  10  in accordance with the present disclosure is illustrated. A separate and optional introducer assembly  12  is also illustrated. 
     As shown, biopsy device  10  is a handheld device and includes a housing  14  to which a stylet  16  is attached. Biopsy device  10  includes several release members  18 ,  20 , and  22 , to be explained in further detail below. 
     Referring to  FIG. 2 , an exploded view of biopsy device  10  is illustrated. As shown, in the exemplary embodiment housing  14  is a two piece member, including a first housing member  14   a  and a second housing member  14   b . In one embodiment, first and second housing members  14   a  and  14   b  are configured snap together to house actuation components of biopsy device  10 . For example, first housing member  14   a  includes one or more slot members  24  positioned on top and bottom portions of first housing member  14   a . Slot members  24  cooperate with and receive latch members  26  that are positioned on top and bottom portions of second housing member  14   b . An interior of housing  14  is generally hollow to receive the actuation components. 
     While housing  14  has been described as snapping together, it is also understood that first and second housing members  14  may alternatively be secured together using fastening elements. 
     A top portion of each housing member  14   a  and  14   b  includes a holder  28  for securing a portion of a resilient bridge member  30 . Each holder  28  extends upwardly from the top portion  32  and includes a groove  34  (best seen in  FIG. 12 ) that receives mounting knobs  36  of a mounting member  38  positioned on a first end  35  of resilient bridge member  30 . 
     An actuating lever  40  is pivotally attached to housing  14  by pivot arm  42  at a proximal end  44  of biopsy device  10 . A forward end  46  of actuating lever  40  may rise upwardly from a top surface of housing  14  due to pivot arm  42 . A lever release assembly  48  that carries a release mechanism  18  is attached to actuating lever  40 . Lever release assembly  48  includes a downwardly extending latch arm  46  that selectively engages with a portion of a retaining member  50  disposed on a cam member  52  carried by a pickup carriage  54  (shown in  FIGS. 3-5 ). A spring mechanism  53  serves to bias release mechanism  18  to an actuation position. 
     Pickup carriage  54  includes a pair of holders  56  that extend upwardly from a top surface thereof. Housing  14  includes an open channel  58  formed in the top surface thereof. When pickup carriage  54  is positioned within housing  14 , holders  56  extend through channel  58  (seen in  FIG. 12 ). Each holder  56  includes a groove  60  that receives a mounting knob  36  from a mounting member  38  positioned on a second end  62  of resilient bridge member  30 . 
     Referring to  FIG. 10 , resilient bridge member  30  includes a plurality of sections that are separated by hinge members  64   a  and  64   b . Hinge members  64   a  and  64   b  are created by V-shaped notches that form thinned sections. 
     First end  35  of resilient bridge member  30  is secured to holders  28  and second end  62  is secured to holders  56  such that resilient bridge member  30  is positioned directly below actuation lever  40  when biopsy device  10  is assembled. Due to the configuration of resilient bridge member  30 , when actuation lever  40  is depressed, actuation lever  40  pushes down on resilient bridge member  30 . The pushing action flattens out resilient bridge member  30 , thereby sliding pickup carriage member  54  away from a distal end of biopsy device  10 . 
     Secured to a top portion of housing  14  is an actuation button carrier  66  that carries release mechanisms  20  and  22 . Release mechanism  20  includes a downwardly extending latch arm  68  that extends downwardly into first housing member  14   a  though an opening  70  formed therein. As will be explained in further detail below, release mechanism  20  is actuated to release stylet  16 . More specifically, an end of latch arm  68  is configured to grip a retaining arm  72  of stylet  16 . When release mechanism  20  is depressed, the end of latch arm  68  is biased upwardly, thereby releasing its grip on retaining arm  72  of stylet  16  and permitting stylet to advance forward. 
     Release mechanism  22  also includes a downwardly extending latch arm (not shown). As will be explained n further detail below, the latch arm of release mechanism  22  releases an outer cutting cannula  74 . More specifically, when release mechanism  22  is depressed, the end of the latch arm of release mechanism  22  is biased upwardly, thereby releasing outer cutting cannula  74  and permitting outer cannula  74  to advance forward. 
     Other components of biopsy device  10  includes a stylet assembly  76 , an outer cannula assembly  78 , a cam member assembly  80 , a support rib  82 , and a piston member  84 . Each element will be discussed in turn below. 
     Stylet assembly  76  is shown in  FIG. 7 . Stylet assembly  76  includes stylet  16 , a first arm sub-assembly  86 , and a second arm sub-assembly  88 . Stylet  16  extends between a distal end  90  and an open proximal end  92 . Adjacent distal end  90  is a tissue opening  94 . Distal end  90  may further include a trocar piercing tip  95 . Stylet  76  further defines an inner lumen  96  that extends between tissue opening  94  and proximal end  92 . Positioned adjacent proximal end  92  are first and second seal members  98 ,  100 , respectively. First seal member  98  is attached a first cap member  102  that is attached to second arm sub-assembly  88 . Second seal member  100  positioned adjacent to a chamber wall member  103 , which is positioned adjacent second end cap  104 . Second end cap  104  is fixedly secured to stylet  16 . Second seal member  100  (see  FIG. 2 ) is disposed between first end cap  102  and chamber wall member  103 . Thus, first end cap  102 , chamber wall member  103 , and first and second seal members  98 ,  100  cooperate with a cylinder  106  to define a vacuum chamber  108 , to be explained in further detail below. 
     A notch  110  is cut into stylet  16 , between first end cap  102  and chamber wall member  103 . Notch  110  is in communication with inner lumen  96 , which, in turn, is in communication with tissue opening  94 . A one-way valve member  109  (to be discussed in further detail below) is attached to open proximal end  92  (see, e.g.,  FIG. 2 ). 
     First arm sub-assembly  86  includes is generally L-shaped and includes a leg member  112  and a carrier member  114 . Carrier member  114  is fixedly secured to stylet  16 . Carrier member  114  includes a fitting member  116  that cooperative engages a side of complimentary member  118  that is disposed on a carrier member  120  that is part of second arm sub-assembly  88 . 
     Second arm sub-assembly  88  includes a long leg member  122  and a short leg member  124  that are connected together by carrier member  120 . When assembled (and as best seen in  FIG. 7 ), short leg member  124  is disposed beneath leg member  112  of first arm sub-assembly  86 , with carrier member  114  being positioned above carrier member  120 . First cap member  102  is attached to carrier member  120 . First cap member  120  is fixedly secured to cylinder  106 . Thus, as vacuum chamber  108  moves, so does second arm sub-assembly  88 . 
     Referring to  FIG. 9 , outer cannula assembly  74  includes an outer cutting cannula  126  that is fixedly attached to an outer cannula hub  128  at its proximal end. Outer cannula hub  128  includes a positioning member  130  on one side and a retaining member  132  on another. Retaining member  132  includes a retaining finger  134 . A distal end  136  of outer cannula  126  is sharpened to sever tissue. 
     Referring to  FIG. 2 , outer cannula assembly  74  is assembled to stylet assembly  76  as follows. First, a bumper member  138  is positioned over stylet  16  and into contact with a mounting face  140 . Support rib  82  is next slid onto stylet  16 . Support rib  82  (best seen in  FIG. 2 ) includes first and second mounting grooves  142 ,  144 . First mounting groove  142  is configured to receive short leg member  124  of second arm sub-assembly  86  and leg member  112  of first arm sub-assembly  86 . Second mounting groove  144  is configured to receive long leg member  122  of second arm sub-assembly  86 . An outwardly extending spring mount  146  is formed on support rib  82 . A biasing member  148 , such as a spring is positioned on spring mount  146 . Outer cannula hub  128  includes a spring mount  150  that receives and end of biasing member  148 . 
     Referring now to  FIGS. 3-6 , pickup carriage  54  and cam member  52  will be described. Pickup carriage  54  includes a first elongated groove  152  and a second shortened groove  154 . A mounting hole  156  is positioned opposite second groove  154 . An access opening  158 . 
     Cam member  52  includes a mounting member  160  that is received within mounting hole  156 . A first pivot member  162  from cam member  52  is positioned within first groove  152  of pickup carriage  54 . A second pivot member  164  from cam member  52  (seen in  FIG. 2 ) is positioned within second groove  154 . Retaining member  50  is positioned on an end of cam member  52  and is received within access opening  158 . 
     A biasing member  166  received on a mounting portion  168  of pickup carriage  54 . A distal end  170  of biasing member  166  contacts first pivot member  162  and biases first pivot member  162  toward a first end  172  of first groove  152 . Pickup carriage  54  may further include a tang member  174  that partially retains a portion of biasing member  166 . 
     A proximal end  176  of pickup carriage  54  includes a mounting post  178 . A biasing member  180  is received on mounting post  178 . An end of biasing member  180  engages an internal wall  182  formed by first and second housing members  14   a  and  14   b  when pickup carriage  54  is installed therewithin. When pickup carriage  54  is installed, holders  56  are oriented to extend upwardly through channel  58  formed through housing  14 . Cam member  52  is installed on a bottom surface  184  of pickup carriage  54  as shown in  FIG. 3 . 
     Referring to  FIGS. 12-20 , operation of biopsy device  10  will now be described. Assuming biopsy device  10  is packaged in the fired position (see  FIG. 12 ), biopsy device  10  must first be moved into the cocked position. To move biopsy device  10  into the cocked position, first release latch  18  is actuated to release actuation lever  40  from housing  14  (see  FIG. 12 ). Actuation lever  40  is then depressed, pushing down on bridge member  30 , which is attached to holders  56  of pickup carriage  54 . Accordingly, when bridge member  30  is depressed, pickup carriage  54  is moved toward proximal end  44  of biopsy device  10 . 
     As pickup carriage  54  moves toward proximal end  44  of biopsy device  10 , a first pickup member  186  contacts a first tang member  188  that is carried on carrier member  120  that is part of second arm sub-assembly  88 , and retracts vacuum chamber  108  proximally, as shown in  FIG. 13 . A first piston spring member  190  that is at least partially positioned over vacuum chamber  108 , is compressed between a proximal face  192  of carrier member  120  and a first lower internal face  194  positioned within housing  14 . A second spring member  196  is compressed between second end cap  104  and a second lower internal face  198  positioned within housing  14 . This action also collapses the vacuum chamber  108 , moving first end cap  102  towards chamber wall member  103 . Air within vacuum chamber  108  is directed out through seal member  109  that is secured to proximal end  92  of stylet  16 . 
     In one embodiment, seal member  109  is a configured as a duck-bill style valve member  109  ( FIG. 2 ). Valve member  109  includes a body member  103  having an open distal end  105  that is connected to a tapered, duck bill, normally closed proximal end  107 . Proximal end  107  includes a slit which is forced open when positive pressure is generated within stylet  16 . Open distal end  105  is secured to proximal end  92  of stylet  16 . 
     An alternative embodiment of seal member  109 ′ is shown in  FIGS. 21A-21D . Seal member  109 ′ includes a body member  111  having an open distal end  119  and a normally closed proximal end. Adjacent to the proximal end of seal member  109 ′ is a slit  113  that cooperates with a land member  115  to form a flap member  117 . Slit  113  extends along a substantial portion of body member  111  such that land member  115  acts as a hinge for flap member  117 . In operation, as positive pressure is generated within the system, flap member  117  will be forced open. 
     Spring member  180  biases pickup carriage  54  back toward a distal end of biopsy device  10 . Actuation lever  40  is depressed again. The second depression of actuation lever  40  causes pickup carriage  54  to move in the proximal direction again. As pickup carriage  54  moves, a second pickup member  200  positioned on cam member  54  contacts a second tang member  202  that is carried on outer cannula hub  128 . Such action retracts outer cannula assembly  74 , moving distal end  136  thereof away from distal end  90  of stylet  16 . Retaining member  132  is compressed inwardly until retaining finger  134  grips an internal ledge (not shown) formed in first housing member  14   a . Retraction of outer cannula assembly  74  causes biasing member  148  to compress between a proximal face  204  of outer cannula hub  128  and a distal face  206  of support rib  82 . 
     Spring member  180  biases pickup carriage  54  once again and actuation lever  40  is depressed a third time. The third depression of actuation lever  40  causes pickup carriage  54  to move proximally once again. As pick up carriage  54  moves proximally, first pickup member  186  engages with fitting member  116  that is carried on carrier member  114  of first arm sub-assembly  86  and pulls first arm sub-assembly  86  towards second arm sub-assembly  88 . Once carrier  114  of first arm sub-assembly  86  reaches carrier  120  of second arm sub-assembly  88 , stylet  16  is pulled into outer cannula  126  and stylet  16  is locked into the cocked position. On the third depression, actuation lever  40  locks down and latch release assembly  48  retains lever  40  against housing  14  (see  FIG. 15 ), thereby providing a tactile indicator that biopsy device is in the cocked position. 
     Biopsy device may also include a visual indicator to indicate that biopsy device  10  is in the cocked position. In one embodiment, at least leg member  112  of first arm sub-assembly  86  may be constructed of a particular color that is different than the color of housing  14  and that will be visible through a window  208  only when biopsy device  10  is in the cocked position. For example, leg member  112  may be formed from a green material such that a portion of the green material is visible through window  208  when biopsy device  10  is in the cocked position so as to be in the “biopsy ready position.” In contrast, when stylet  16  is in a non biopsy ready position, leg member  112  will be positioned away from indicator window  208 . 
     Once in the cocked position, or biopsy ready position, a biopsy may be performed. The operation will now be explained. 
     Typically, before a biopsy is performed, a targeted area must be identified. Any suitable method may be used to identify a targeted area for biopsy. Such methods include, but are not limited to, the methods and use of the devices described in co-pending application Ser. No. 10/649,068, the contents of which are incorporated herein by reference in its entirety. 
     Next, the entry site is prepared, as required (such as applying anesthesia, cleaning the biopsy area, etc.). During this step, an introducer assembly  12  (see  FIG. 1 ) may be positioned over outer cannula  112  to provide a pathway to the target area. Introducer assembly  12  will be explained in further detail below. 
     Next, a tip of stylet  16  is placed at the targeted area. In one embodiment, stylet  16  may be fired prior to inserting biopsy device  10  into the patient. In another embodiment, stylet  16  is not fired until after biopsy device  10  is inserted into the patient. In one embodiment, the position and orientation of biopsy device  10  is maintained during the firing process. 
     A stylet release or firing member  20  is depressed, thereby releasing stylet assembly  76  from its cocked position into the fired position ( FIG. 16 ). Such action exposes tissue opening  94  into which tissue may prolapse. Tissue receiving opening  94  is connected to inner lumen  96 . Inner lumen  96  is connected to vacuum chamber  108 . 
     To differentiate between stylet release member  20  and an outer cannula release member  22 , stylet release member  20  may be a different color than housing  14  or outer cannula release member  22  (to be described below) to allow a user to visually differentiate between the two release members. In one embodiment, one of stylet and outer cannula release members  20 ,  22  may alternatively include a tactile indicator, such as a raised bump  210  on the release member, to allow a user to feel the differences between the two release members (see, e.g.,  FIGS. 1 and 11 ). 
     After stylet release member  20  is actuated, outer cannula release member  22  is then actuated. This action will release outer cannula assembly  78 . Outer cannula assembly  78  is forced over stylet  16  by biasing members/springs  148 ,  190 , and  196 , such that outer cannula assembly  78  rapidly fires forward. As outer cannula assembly  78  is fired forward, vacuum chamber  108  is expanded so as to create a vacuum by drawing air through tissue opening  94  and lumen  96 , and entering into vacuum chamber  108  through notch  110 . A further explanation of the vacuum chamber may be found in commonly owned and co-pending U.S. application Ser. No. 11/389,274, the contents of which are incorporated herein by reference in its entirety. 
     In one embodiment (not shown), a vacuum valve having a slit that creates a flap may be provided that selectively covers the notch. When stylet  16  is fired forward, positive pressure generated inside vacuum chamber  108  closes the valve flap to prevent pressure from reaching the inside of lumen  96 . When outer cannula  74  fires forward, the negative pressure inside vacuum chamber  108  opens the valve, allowing vacuum to be delivered to tissue opening  94  in stylet  16 , through lumen  96 . 
     As outer cannula assembly  78  is fired and vacuum is generated by the expansion of vacuum chamber  108 , the vacuum biases tissue toward tissue opening  94  and holds tissue in place while outer cannula  74  slides over tissue opening  94 . As outer cannula  74  slides, sharpened distal end  136  slices through the tissue, thereby severing the tissue so as to leave a biopsy core  212  within tissue opening  94 . 
     Once biopsy core  212  is acquired, to retrieve biopsy core  212  from biopsy device  10 , biopsy device  10  is removed from the patient. If an introducer assembly  12  is used, it is kept in position within the patient. Once removed from the patient, release member  18  is depressed once again to release latch member  26 . Latch member  26  is depressed twice to pull back outer cannula  74  so as to expose tissue opening  94  (see  FIGS. 18-20 ) and biopsy core  212 . To obtain additional biopsy cores  212 , the latch member  26  is depressed a third time ( FIG. 20 ) to retract stylet  16  into the biopsy ready position. 
     Referring to  FIGS. 1 and 11 , introducer assembly  12  will now be explained. Introducer assembly  12  includes an introducer cannula  214  that is fixedly connected to an introducer hub  216 . Introducer cannula  214  is hollow and is sized to slide over outer cannula  74  so as to be spaced proximally from distal end of outer cannula  74 . Introducer hub  216  may include a normally closed valve (not shown) and includes an opening that is in communication with introducer cannula  214 . Disposed on introducer hub  216  is a selectively releasable latch member  218  that includes a connecting member  220  and a releasing member  222 . Releasing member  222  is received within an opening  224  to secure introducer assembly  12  to biopsy device  10 . 
     In operation, introducer assembly  12  is positioned over outer cannula  74  and slid along outer cannula  74  until connecting member  220  of latch member  218  is received within opening  224 , thereby connecting introducer assembly  12  to biopsy device  10 . Introducer assembly  12  may be connected to biopsy device  10  either before or after biopsy device is placed in the biopsy ready position. Once connected, biopsy device  10  is inserted into the patient with introducer cannula  214 . Introducer cannula  214  operates to maintain a pathway to the biopsy site. 
     Once biopsy cores  212  are taken, biopsy device  10  may be detached from introducer assembly  12  by depressing releasing member  222  such that connecting member  220  is released from opening  224 . Once freed, introducer cannula  214  remains within the patient&#39;s body, to maintain the pathway to the biopsy site. Use of introducer assembly  12  minimizes trauma to the patient and eliminates the need for multiple reinsertions of biopsy device  10 , as well as permits access to the biopsy site for treatment and other post biopsy activities. As such, after the biopsy cores  212  are removed from tissue opening  94 , biopsy device  10  may be reinserted into introducer cannula  214  to take addition biopsy cores  212 . 
     Alternatively, if desired, a biopsy marker (not shown) may be deployed into the biopsy cavity after biopsy cores  212  have been taken. In such a case, a site marker deployment device may be inserted within introducer assembly  12  after biopsy device  10  is removed therefrom. Once such example of a site marker deployment device is disclosed in commonly owned and co-pending application Ser. No. 11/238,295, the contents of which are incorporated herein by reference in its entirety. 
     Referring now to  FIGS. 22 and 23 , another embodiment of a biopsy device  300  is illustrated. Biopsy device  300  includes the same components as biopsy device  10 , except that distal end  301  of stylet  316  is formed with a blunt tip  302  rather than a trocar tip, as shown with stylet  16 . 
     Blunt tip  302  is useful for those instances where a lesion to be biopsied is close to the chest wall. More specifically, the length of blunt tip  302  is shorter than the length required for a trocar tip, thereby permitting access to a lesion close to a chest wall. 
     However, because there is no trocar tip, to position biopsy device  300  at a target area within the body, a separate trocar device (not shown) must be used to create a pathway for the stylet  316  and cutting cannula  74 . An example of a trocar device is shown and described in commonly owned U.S. Pat. No. 7,347,829, the contents of which are incorporated in its entirety. As may be seen, the trocar device is defined by an elongated body having a sharp distal end. The proximal end of the trocar device may also include handle. 
     In operation, once the target area is defined, the trocar device is inserted into the patient to create a pathway to the target site. In one arrangement, introducer assembly  12  is used with the trocar device. More specifically, and as described in U.S. Pat. No. 7,347,829, trocar device is inserted into the introducer cannula  214  prior to insertion of the trocar device into the patient&#39;s body. A target confirmation device (as described and disclosed in U.S. Pat. No. 7,347,829) may then be used to verify that the pathway created by the trocar device has reached the target site. In one embodiment, the trocar device may be used as the target confirmation device. In another embodiment, the target confirmation device is a separate component that may inserted into the pathway after removal of the trocar device. When the trocar device is removed from the patient&#39;s body, the introducer cannula  214  will remain within the patient&#39;s body to hold open the pathway to the target area. 
     Once the pathway to the target site is defined, the distal end  301  of the biopsy device  300  is inserted into the introducer cannula  214  until distal end  301  extends outwardly from a distal end of the introducer cannula  214 . Releasing member  222  may be inserted into the opening  224  formed on the housing of biopsy device  300  in a similar fashion as described in connection with the biopsy device  10 . Once inserted through the introducer cannula  214 , the biopsy device  300  may be operated in the same manner as described in connection with biopsy device  300 . 
     While the embodiments of the present invention has been particularly shown and described with reference to the foregoing preferred embodiments, it should be understood by those skilled in the art that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention without departing from the spirit and scope of the invention as defined in the following claims. It is intended that the following claims define the scope of the invention embodiments within the scope of these claims and their equivalents be covered thereby. This description of the invention should be understood to include all novel and non-obvious combinations of elements described herein, and claims may be presented in this or a later application to any novel and non-obvious combination of these elements. The foregoing embodiment is illustrative, and no single feature or element is essential to all possible combinations that may be claimed in this or a later application.