Abstract:
A biopsy device used to capture a tissue sample by placing the tissue under tension, thus allowing a greater sized sample with increased quality. The device uses a rotating cannula and stylet with a concave “sample notch.” The rotation of the stylet places the tissue under tension while the rotation of the cannula as it is fired severs the sample.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims priority to currently pending U.S. Provisional Patent Application 60/595,546, filed Jul. 13, 2005. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The invention relates generally to biopsy needles. Specifically, the present invention relates to improvements to conventional tissue biopsy devices and results in a larger core sample.  
       BACKGROUND OF THE INVENTION  
       [0003]     A number of biopsy needles of the prior art have been designed to capture a tissue sample in a stylet having a purchasing recess, into which the sample prolapses after the needle has been inserted. Generally, a cutting cannula is fired thus severing the sample and trapping the sample within the recess.  
         [0004]     U.S. Pat. No. 5,718,237 to Haaga describes a biopsy needle that has a coaxial, telescopically interengaged stylet, inner and outer cannulas (the stylet axially and rotatably displaceable relative to the cannula). The stylet has a distal portion provided with a cutting recess (notch) for severing a biopsy specimen, and the inner cannula has a distal portion for cutting and capturing the specimen in the recess. In operation, the device is inserted into the target area and the stylet is displaced into the tissue. The notch is thereby placed within the lesion. The stylet is then rotated about its axis to sever the tissue. The inner cannula is then displaced to cover the stylet and trap the tissue within the lesion. The inner cannula is equipped with a cutting edge to sever tissue as it is displaced.  
         [0005]     The &#39;237 patent to Haaga relies on the cutting action of the inner stylet to purchase the lesion, therefore relying on the natural prolapse of tissue into the purchasing recess. Furthermore, the &#39;237 does not provide a rotating cannula which serves to make a cleaner cut and capture a larger sample within the purchasing recess.  
         [0006]     U.S. Pat. No. 6,673,023 and U.S. Patent Application 2004/0059254 to Pflueger describe an apparatus for removing tissue and/or other material from a patient. The biopsy device includes a hand piece and a tissue removal mechanism. The tissue removal mechanism includes a cannula having an open distal tip. The mechanism further includes a rotatable element having a distal portion with helical threading. The distal portion of the rotatable element extends beyond the open distal tip of the cannula in order to allow tissue to prolapse between turns of the helical threading. The apparatus is designed to draw soft tissue into the cannula upon rotation of the rotatable element and without the need for supplemental sources of aspiration. The &#39;254 application relies on a helical structure, rather than a sample notch, to draw tissue into the cannula.  
         [0007]     Therefore, what is needed is a core biopsy device which captures a biopsy sample under tension greater than that provided by the natural prolapse of the tissue, thus providing a larger sample for analysis.  
       SUMMARY OF THE INVENTION  
       [0008]     The present invention includes a core biopsy needle having a tubular outer cannula and a telescopically integrated stylet disposed within the outer cannula whereby the stylet and cannula are coaxial in orientation. A purchasing recess is disposed within the stylet whereby the stylet and cannula are rotateable along a common axis in opposite directions such that the counter-rotation of each severs and captures a biopsy sample within the purchasing recess. The rotating stylet initially places the targeted tissue under tension maximizing the quantity of specimen by overfilling/gathering tissue in the sampling notch; secondly the counter rotating cutting cannula takes advantage of said tissue hence cutting a larger more intact/quality sample. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]      FIG. 1  is an isometric view of the present invention without specimen before it is inserted.  
         [0010]      FIG. 2  is a cross-sectional view of the sidewall of the receiving recess.  
         [0011]      FIG. 3  is an isometric view of one embodiment of the device wherein the receiving recess as a leading side wall with a length greater than the linear length of the recess.  
         [0012]      FIG. 4  is an isometric view of the cutting edge of the cannula showing one embodiment wherein the cutting edge is helical.  
         [0013]      FIGS. 5-7  are isometric views of the insertion of needle before it is rotated.  
         [0014]      FIGS. 8-10  are isometric views of the counter rotation occurring on both outer cannula and inner stylet.  
         [0015]      FIGS. 11-13  are isometric views of the needle rotating while it cuts and secures the specimen.  
         [0016]      FIGS. 14-16  are isometric views of the needle being withdrawn with sample specimen in tact.  
         [0017]      FIG. 17  is an isometric view of needle after it is withdrawn with specimen secured within.  
         [0018]      FIG. 18  is an isometric view of needle showing accessibility to specimen.  
         [0019]      FIG. 19  is an isometric view of the inventive apparatus detailing the cutting point of one embodiment, where the cutting edge of the cannula meets the leading side wall of the receiving recess. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0020]     In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings, which form a part hereof, and within which are shown by way of illustration specific embodiments by which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the invention.  
         [0021]     Referring now to  FIG. 1 , a preferred embodiment of the invention is shown illustrating the component parts of the novel biopsy device  10  in accordance with the present invention. As shown in  FIG. 1 , biopsy device  10  includes tubular outer cannula  20  which carries solid circular stylet  30 . Outer cannula  20  is circular in cross-section, has an axis and circular passageway there through. Outer cannula  20  and stylet  30  are coaxial when assembled and have a common axis. Outer cannula  20  is equipped with distal portion  23  which is preferably tapered. The end of outer cannula  20  proximal to the user is generally equipped with a handle by which biopsy device  10  is manipulated during use. In one embodiment cutting edge  25  of cannula  20  is beveled or otherwise adapted to present a helical cutting surface.  
         [0022]     Stylet  30  is solid and circular in cross-section, having a diameter which allows the stylet to be received within cannula  20  and supported therein for axial and rotative displacement relative thereto. Stylet  30  includes distal portion  33  and a proximal portion (not shown) extending axially there from. In a general embodiment, proximal end of cannula  20  and stylet  30  are provided with a handle to facilitate manipulation of the biopsy device, particularly with respect to the orientation of cannula  20  and stylet  30  relative to one another. The axially outer end of distal end  33  of stylet  30  is beveled to provide a distal tip  33   a . A portion of stylet  30  is radially and axially cut away at a location spaced axially inward from distal end  33  to provide specimen receiving recess  35 . Recess  35  includes side walls  37   a  and  37   b  which aid in placing the tissue to be sampled at the biopsy site under tension during use of the device.  
         [0023]     As shown in  FIGS. 1 through 3 , stylet  30 , is best described as a solid rod; the distal end  33  of which is equipped with a concavity to form specimen receiving recess  35 . Receiving recess  35  defines a fully cylindrical volume, said volume having a cross-sectional area only slightly less than that of stylet  30 . Receiving recess  35  is bordered along an extent of its perimeter by side wall  37 ; further comprising leading side wall  37   a  and trailing side wall  37   b.    
         [0024]     In one embodiment, side wall  37  has a cross-section greater than 180° when viewed along its length ( FIG. 2 ). In addition to enhancing sample collection, discussed below, the extended cross-section of side wall  37  helps to protect large samples from being displaced from recess  35  as cannula  20  is fired over stylet  30 . The length of recess  35  can be varied to fit the intended purpose of the device.  
         [0025]     In this embodiment, leading side wall  37   a  has a length greater than the length of recess  35 , see  FIGS. 2 through 3 . In addition to the protective function, discussed above, this leading edge design provides a greater contact surface area between stylet  30  and the sample tissue. Accordingly, leading wall  37   a  can be adapted with a surface designed to grasp, or aid in the severing of tissue as stylet  30  rotates.  FIG. 2  shows cross-section with constant wall thickness for the stylet. In alternate embodiments, however, receiving area  35  has a variable wall thickness with more material in the wall at the central region of the cross-section.  
         [0026]     Referring now to  FIGS. 1 through 4 , cannula  20  is an elongated, tubular member having an enclosed section comprising an annular wall, defining a lumen there through. The inner diameter of the lumen is somewhat greater than the outer diameter of stylet  30 , to provide a sliding fit of the stylet therein.  
         [0027]     Cannula  20  terminates at its distal end in cutting edge  25 . In one embodiment, cutting edge  25  on the distal end of cannula  20  is inclined relative to the longitudinal axis of the cannula to define an elliptical beveled edge. Cutting edge  25  can be provided with a secondary bevel, thereby sharpening the beveled edge and enhancing the severing capability of the cannula. Alternatively, cutting edge  25  of cannula  20  can be manufactured with a variety of shapes including, but not limited to, spherical, conical, cylindrical and helical (see  FIG. 4 ). It is preferable that cutting edge  25  be made of a material which can provide a high degree of sharpness, i.e. steel or ceramics. In another embodiment, all steel components can be made of non-ferrous material metals for use in MRI applications.  
         [0028]     When assembled, cannula  20  and stylet  30  are displaceable between retracted and extended positions relative to one another. Prior to use both elements are in the retracted position.  FIGS. 2 through 4  illustrate the biopsy device in use, beginning with both cannula  20  and stylet  30  are in the retracted position.  
         [0029]     In an embodiment illustrative of the operation of the device, cannula  20  and stylet  30  are urged forward, with the stylet in the retracted position, into the body of a subject to a point adjacent the lesion to be sampled  40 . Once cannula  20  and stylet  30  are proximate to lesion  40 , distal end  33  of stylet  30  is urged forward and enters lesion  40  in leading relation to cannula  20  ( FIGS. 5 through 7 ). When so positioned, stylet  30  is displaced axially outward relative to cannula  20  from its retracted position to its extended position in which recess  35  is located at the biopsy site as shown in  FIG. 8 .  
         [0030]     Stylet  30  rotates about its axis as indicated by arrow A 1 ,  FIGS. 9 through 14 , urging the tissue specimen at the biopsy site into recess  35 . Cannula  20  is then displaced axially outwardly relative its retracted position. Cannula  20  is rotated about its axis in the opposite direction of stylet  30  as indicated by arrow A in  FIGS. 9-14 . In one embodiment, during the movement of cannula  20 , cutting edge  25  at the distal end thereof severs the tissue at the biopsy site into recess  35  of stylet  30 . In passing axially and radially across recess  35 , cannula  20  radially captures a larger biopsy specimen therein ( FIG. 15 ).  
         [0031]     Once the specimen is captured within recess  35  of stylet  30 , the biopsy device is withdrawn ( FIGS. 15 through 17 ). Once fully withdrawn, as shown in  FIG. 18 , cannula  20  is retracted exposing recess  35  of stylet  30  which now houses biopsy specimen  40   a.    
         [0032]     Stylet  30  and cannula  20  work in conjunction to sever and trap the sample in recess  35 . The rotation of both stylet  30  and cannula  20  is such that the sample is severed at cutting point X ( FIG. 19 ). As detailed in  FIG. 19 , cutting edge  25  of cannula  20  and leading wall  37   a  of stylet  30  meet at cutting point X during their rotation. When cannula  30  is fired to the severing position, the sample is severed from the surrounding tissue by the combination of the force exerted by the rotation of stylet  30  and the movement (linear and/or rotating) of cannula  20 .  
         [0033]     The rotation of stylet  30  and cannula  20  results in the device severing the sample from the surrounding tissue; thereby forming a substantially cylindrical sample. In one embodiment, cannula  20  is rotated approximately 1½ turns, relative to stylet  30 , to ensure that the sample has been completely severed from the surrounding tissue.  
         [0034]     In an alternate embodiment, rotation of the cannula is limited to prevent the leading point of cannula  20  from entering into the cutting area of the tissue during rotation. The angle between cutting edge  25  of cannula  20  and leading wall  37   a  of stylet  30  are roughly inverted in this embodiment as the cutting edge  25  of cannula  20  passes over leading wall  37   a  of stylet  30  (see  FIG. 19 ).  
         [0035]     In another embodiment, cutting edge  25  of cannula  20  and leading wall  37   a  of stylet  30  form an acute angle at cutting point X such that the cutting action is like that of a scissor at point X; however, at locations away from point X, the cutting action is similar to a standard biopsy device. Cutting edge  25  of cannula  20  may alternatively be angled such that it forms an obtuse angle with leading wall  37   a  of stylet  30 . In this embodiment, the motion shown in  FIG. 19  results in somewhat of a slicing action; like that of a knife. While these incident angles are illustrative of the inventive device, they are not intended to be limiting.  
         [0036]     However, the rotation need only be sufficient to ensure the separation of the sample from the tissue mass. Rotation can therefore encompass multiple or even partial revolutions of the cannula and/or stylet; as well as combinations thereof. This severing action remains effective in embodiments wherein the stylet and cannula rotate the same direction or in counter rotation; as well as in embodiments wherein the stylet and cannula rotate at different times during the taking of the sample.  
         [0037]     In some embodiments, the inventive device can include a firing mechanism that includes a first and second trigger configured to selectively control the operation of the stylet and the cannula. The firing mechanism can also be adapted to actuate both the cannula and stylet sequentially. For example, the advancement of cannula  20  to the severing position can be done as part of, or separate from, the rotation of stylet  30 . In one embodiment, the advancement of cannula  20  is accomplished in the same step as the rotation of stylet  30 .  
         [0038]     While the cannula and stylet of the present invention are described herein as being provided with handles for manipulation of the component parts relative to one another, it will be appreciated that the biopsy device is operable in the manner of a standard side cut needle whereby these component parts are adaptable to automated operation. These and other modifications of the preferred embodiment, as well as other embodiments of the present invention, will be obvious to those skilled in the art from the disclosure of the preferred embodiment herein.  
         [0039]     It will be seen that the objects set forth above, and those made apparent from the foregoing description, are efficiently attained and since certain changes may be made in the above construction without departing from the scope of the invention, it is intended that all matters contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.  
         [0040]     It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween. Now that the invention has been described,