Abstract:
In an automatic biopsy device comprising a housing in which a biopsy needle is axially movably supported by a needle support structure and a canula extending around the needle is axially movably supported by a canula support structure, and first and second spring force storage structures are provided for biasing the biopsy needle and the canula, respectively, toward an extended position and the biopsy needle and canula support structures are held in a retracted position by respective first and second releasable locking means, releasing means are provided for manually releasing the first locking means to permit the needle to be propelled by the first spring force storage structure and to release the second locking structure by releasing means of the needle support structure to permit the canula to be propelled by the second spring force storage structure, the biopsy needle and canula and also the spring force storage structures consisting of a non-magnetizable electrically non-conductive material.

Description:
[0001]    This is a Continuation-In-Part application of international application PCT/EP01/08957 filed Aug. 8, 2001, and claiming the priority of German application 100 42 519.4 filed Aug. 3, 2000.  
         BACKGROUND OF THE INVENTION  
         [0002]    The invention resides in a biopsy device for the removal of soft tissue samples from a living organism including a housing supporting a biopsy needle with recesses in its sides near the tip of the needle, a canula which is axially movably disposed on the needle, a spring for moving the needle forwardly and a spring for moving the canula forwardly.  
           [0003]    In human and veterinary medicine, a targeted removal of soft tissue samples from the living organisms, called biopsy, is a solid part of the diagnosis in connection with numerous health problems. Often, only the examination of a tissue sample permits a safe diagnosis. Whereas a biopsy is performed usually on body parts which are accessible from the outside by surgical instruments, endoscopic procedures must be used for biopsies on internal body parts using for example a biopsy needle. The biopsy needle, which has a recess at its side near its tip, is inserted into the tissue to be examined so that the tissue enters the recess. Then a canula is moved forwardly over the recess toward the needle tip whereby the tissue in the recess is severed and removed with the needle for examination.  
           [0004]    There are three different types of biopsy devices. In manual biopsy devices, the needle is normally inserted and the canula is manually moved forwardly. In semiautomatic biopsy devices, the needle is manually inserted, but the canula is moved at high speed forwardly over the recess of the biopsy needle by the release of a compressed spring. Automatic biopsy devices include generally two spring force storage structures, one for the rapid forward movement of the biopsy needle into the predetermined target area and the other for the immediately following rapid forward movement of the canula.  
           [0005]    WO96/39941 discloses an automatic biopsy device which comprises a housing with a biopsy needle and a canula supported therein so as to be axially movably disposed on the biopsy needle. It also includes for each a spring structure with a metal spring for a spring force driven forward movement of the biopsy needle and the canula. For the automatic operation, first both springs are manually compressed or tensioned, whereby two guided members, on which the biopsy needle and the canula are mounted, are retracted to an end position in which they are compressed or tensioned. Two guided members on which the biopsy needle and the canula are mounted are retracted thereby to an end position where they are held by a simple locking mechanism disposed eccentrically with respect to the canula and the biopsy needle. After the biopsy device is properly positioned, the locking mechanism for the biopsy needle is released whereby the needle is propelled by spring force toward the target area. Shortly before reaching the target area, the movement of the biopsy needle releases in the housing the locking mechanism for the canula resulting in a spring force operated advance of the canula. However, the biopsy device includes several metallic components, which are for example springs consisting of spring steel. This causes in the MRT picture distortions (artifacts) Steel springs are consequently not very suitable for use with MRT. The biopsy needle with the canula is provided in the form of a replacement unit in the housing with the two spring force storage structures.  
           [0006]    However, if during an MRT examination a carcinoma is detected and if based on the image, a tissue sample is to be taken in the MRT, the biopsy device and the manipulator must be of such a design that no artifacts occur.  
           [0007]    It is the object of the invention to provide a biopsy device with a spring force storage arrangement so that it is suitable for an image-based operation with an MRT in which strong magnetic fields (&gt;1 Tesla) are present. Furthermore, the kinematics of the biopsy device should be improved so as to facilitate the replacement of the biopsy needles and canulas and to improve generally the operation of the device.  
         SUMMARY OF THE INVENTION  
         [0008]    In an automatic biopsy device comprising a housing in which a biopsy needle is axially movably supported by a needle support structure and a canula extending around the needle is axially movably supported by a canula support structure and first and second spring force storage structures are provided for biasing the biopsy needle and the canula, respectively, toward an extended position and the biopsy needle and canula support structures are held in a retracted position by respective first and second releasable locking means, releasing means are provided for manually releasing the first locking means to permit the needle to be propelled by the first spring force storage structure to release the second locking structure by releasing means of the needle support structure to permit the canula to be propelled by the second spring force storage structure, the biopsy needle and canula and also the spring force storage structures consisting of a non-magnetic electrically non-conductive material.  
           [0009]    The invention will be described in greater detail below on the basis of the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    [0010]FIG. 1 is a cross-sectional view of a first embodiment of the invention including two fluid spring storage structures,  
         [0011]    [0011]FIGS. 2 a  to  2   c  show the charging procedure of the biopsy device shown in FIG. 1,  
         [0012]    [0012]FIG. 3 a  to FIG. 3 c  show the needle and canula insertion procedure with the device according to FIG. 1,  
         [0013]    [0013]FIG. 4 is a sectional view of a second embodiment of the biopsy device using two spiral spring force storage structures,  
         [0014]    [0014]FIG. 5 is a sectional view of a third embodiment using two rubber tension springs as spring force storage structures,  
         [0015]    [0015]FIG. 6 a  to FIG. 6 e  show, for the embodiment according to FIG. 5, a housing structure which can be opened to provide access to the interior, and  
         [0016]    [0016]FIGS. 7 a  to  7   d  show another opening structure for device shown in FIG. 5. 
     
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0017]    [0017]FIG. 1 shows a first embodiment of the biopsy device in a rest position that is in a position in which the springs are relaxed. It includes a housing  1  with two spring force storing structures comprising two bores  2  and  3  each including a piston  4 ,  5  with seals  6  and  7 . The two bores  2  and  3  may be blind bores forming cylinder chambers. The bores  2 ,  3  include above the pistons  4  and  5  a gas which may be compressed to bias the pistons  4 ,  5  onto the seats  10  and  11  of the housing  1 . The bores  12  and  13  in the pistons  4  and  5  are in communication with the cylinder chambers  2 ,  3  of the housing and commonly form an enlarged storage volume for the pressure medium  9 . With the relatively large pressure fluid volume, the volume change caused by a movement of the piston is relatively small so that the pressure gradient during movement of a piston  4 ,  5  is also relatively small. The pistons  4  and  5  extend through the housing  1  and beyond the seats  10  and  11  and are each connected to a respective cap  14  and  15  so as to be movable therewith.  
         [0018]    The piston  5  is provided with a projection  16 , which extends into a circumferential groove of a coupling member  17  having an axis coinciding with the axis of symmetry  8  of the device. The coupling member  17  firmly engages the biopsy needle  18  and is axially movably supported in the central bore  21 . At the end of the coupling member  17  opposite the biopsy needle  18 , there are at least two resilient webs  19 , which are provided at their upper ends with engagement hooks. At its end adjacent the biopsy needle  18 , the coupling member  17  is provided with an inwardly directed conical area  20 , which opens toward the biopsy needle  18 .  
         [0019]    In a similar way, a projection  22 , which is connected to the piston  4 , extends into a circumferential groove formed in the rotationally symmetrical coupling member  23 , which serves as a carrier for the canula  24  and to which the canula  24  is firmly connected. Also, the coupling member  23  is axially movably supported in the bore  21 . At the end of the coupling member  23  remote from the canula, the coupling member  23  carries at least two resilient webs  25 , which are provided at their free ends with engagement hooks.  
         [0020]    As shown in FIG. 1, the biopsy needle  18  is inserted into the canula  24  from the coupling member end thereof and is slidably supported in the canula with little or no play.  
         [0021]    The two coupling members  17  and  23 , which are arranged in axial alignment one behind the other in the bore  21  and which are firmly connected to the biopsy needle  18  and, respectively, the canula  24 , ensure that the biopsy needle  18  as well as the canula  24  are guided accurately along the axis of symmetry  8  without any other guide elements.  
         [0022]    In the center part of the bore  21  between the two coupling members  17  and  23 , a circumferential shoulder  26  is provided. Another circumferential shoulder  27  is at the upper end of the bore  21 . The shoulders  26  and  27  serve as engagement ledges for the locking hooks of the engagement webs  19  and, respectively,  25 , when they are in their retracted end positions in which the spring force storage devices are tensioned. The engagement webs  19  and  25  of the coupling members  17  and  23  are distributed around the circumference of the respective coupling members and the axis of symmetry  8  so that the coupling members  17  and  23  are supported in alignment with the axis of symmetry  8  and are not subject to cogging. Since the projections  16  and  22  extend relatively far into the grooves of the respective coupling members  17  and  23  preferably in the form of a fork, the engagement forces are advantageously distributed at opposite sides of the axis of symmetry  8 , thereby avoiding the transmission of moments to the needle and, respectively, the canula. Cogging of the coupling members  17  and  23  in the bore  21  is therefore very unlikely.  
         [0023]    At the upper end of the housing, an actuating pin  28  is axially movably supported in an end bore  30  of the housing  1  for initiating the biopsy procedure. At its front end, the actuating pin  28  has a conical end surface  29 , which is disposed in the bore  21  for unlocking the elastic webs  19  from the shoulder  27 .  
         [0024]    [0024]FIGS. 2 a  to  2   c  show the tensioning procedure of the biopsy device according to the first embodiment. FIG. 2 a  shows the biopsy device in the rest position, in which both spring force storage structures are released, that is, the two pistons  4  and  5  are seated on the stops  10  and  11  engaging them with a force according to the pre-pressurized pressure medium  9 . (See also FIG. 1). In the following step as shown in FIG. 2 b , the piston  5  is pushed by hand via the cap  15  into the bore  3  of the housing  1  whereby the pressure medium  9  is further compressed. Concurrently, with the piston  5 , the coupling member  17  with the biopsy needle  18  is retracted until the locking hooks at the ends of the webs  19  engage the shoulder  27 . Subsequently, or at the same time, the canula  24  with the coupling member  23  and the piston  4  are retracted via the cap  14  against the pressure of the pressure medium  9  in the cylinder bore  2  until the locking hooks at the free ends of the webs  25  engage the shoulder  26  (FIG. 2 c ). Both spring force storage structures are now under tension. The biopsy device is now ready for use.  
         [0025]    [0025]FIGS. 3 a  to  3   c  illustrate the insertion procedure for taking a tissue sample. The pistons  4  and  5  are at the beginning pressurized by the pressure medium  9 . The locking hooks of the webs  25  and  19  of the coupling members  17  and  23  hold the biopsy needle  18  and the canula  24  in the retracted position. Upon manual insertion of the actuating pin  28  into the housing  1 , the elastic webs  19  of the coupling member  17  are pushed together inwardly by the conical end surface  29  so that, finally, the locking hooks are pushed off the shoulder  27  and the coupling member is released. Driven by the pressure medium, the biopsy needle  18  then is rapidly propelled forwardly into a patients tissue of which a sample is to be taken until the piston abuts the stop  11 . Shortly before this instant the conical surface area  20  of the coupling member  17  engages the webs  25 , which are thereby pushed toward each other so that the locking hooks of the webs  25  are pushed off the shoulder  26 , whereby the coupling member  23  is released (FIG. 36) so that the pressurized piston  4  can impel the canula  21  over and toward the front of the biopsy needle  18 . The forward movement of the canula  24  is limited by the seating of the piston  4  on the stop  10  (FIG. 3 c ). Because of the high speed of the canula  24 , the tissue  32  present in the recess  31  of the biopsy needle  18  is cut off and the canula  24  encloses the tissue sample  33 . The biopsy device is now in its rest position and can be removed from the tissue for an examination of the tissue sample collected in the needle recess.  
         [0026]    For the removal of the tissue sample  33 , the canula  24  is manually pulled back by pushing back the cap  14 , whereby the recess  31  is exposed and the tissue sample  33  can be removed from the recess of the needle.  
         [0027]    The biopsy device of the second embodiment is shown in FIG. 4 in a rest position. It is different from the embodiment described above in that it is equipped, instead of a pressure medium  9 , with compression springs  34  and  35 , which act on the pistons  36  and  37 . The operation of the device shown in FIG. 4, particularly the charging and release procedure according to FIGS. 2 a  to  2   c  and  3   a  to  3   c , are the same as described for the embodiment of FIG. 1.  
         [0028]    [0028]FIG. 5 shows a biopsy device in a third embodiment in a rest position, that is with the springs relaxed. In contrast to the two embodiments described above, each of the spring storage devices includes at least one highly elastic rubber tension spring  38  each being pre-tensioned already in the rest position. The rubber springs  38  extend axially through bores in the pistons  4  and  5  and have at their opposite ends head portions by which they are supported, at one end in the housing  1  near the seals  10  and  11  and, at the opposite end, they are fixed to the pistons  4  and  5 . In this embodiment, the caps are not present by way of which the springs are tensioned like in the first two embodiments. Rather, the pistons  4 ′ and  5 ′ are each provided with operating handles  39  and  40  which extend from the housing  1  through guide slots  41  and  42 .  
         [0029]    As spring force storage elements highly elastic bands, preferably rubber bands, are suitable which rubber bands are guided outside the housing and are attached thereto. They may act on carrier members, which transfer their movement to the biopsy needle and the canula within the housing. The carrier members may be guided together with a slide member parallel to the advance movement path of the biopsy needle and the canula. Like in the earlier described embodiments, the movement is transferred to the coupling members of the biopsy needle and the canula by projections, which extend into openings in the coupling members (see reference numerals  16  and  22  in the figures). Functionally, the slide members replace the pistons  4  and  5  of the embodiments described earlier. This particular variant is not shown in the drawings.  
         [0030]    In all the embodiments described the biopsy needle  18  and the canula  24  form, together with the coupling members  17  and  23 , a separate design unit. This unit may be in the biopsy device a one-way unit, which is easily replaceable. If the replacement of this unit is required, the housing  1  of the biopsy device should be so designed that the central bore  21  is accessible for the replacement. Below, on the basis of FIGS. 6 and 7, two design concepts are presented. In these embodiments, rubber springs are shown but any of the spring arrangements referred to earlier may be used instead.  
         [0031]    [0031]FIGS. 6 a  to  6   c  show an opening mechanism for the central bore  21  in top and side views, wherein the housing  1  includes the spring force storage devices  43  and is provided with a door  44 . The door  44  is supported so as to be pivotable about the center part of one of the two spring force storage structures  43  and are provided with a snap lock structures  43  and is provided with a swap lock  45  for locking engagement with the other spring force storage structure. FIGS. 6 a  and  6   b  show the biopsy device closed, FIGS. 6 c  to  6   e  show it with the door  44  open, whereby the central bore  21  is accessible from the side. As apparent from FIGS. 6 b  and  6   c , it is not necessary to open the side of the housing  1  remote from the biopsy needle for the insertion of the replaceable unit described above.  
         [0032]    In this way, this area of the housing is not weakened so that the opening mechanism as described may also be used for a biopsy device according to the first embodiment with pressure medium-based spring force storage structures as shown in FIGS.  1  to  3 , in which particularly this area of the housing  1  is stressed by the pressure of the pressure medium  9 .  
         [0033]    As an alternative, also the second variant of the opening mechanism is suitable wherein, as shown in FIGS. 7 a  to  7   d , the housing  1  is divided along the central bore  21  such that two housing halves each with one spring force storage element are formed. FIGS. 7 a  and  7   b  show such a biopsy device in a closed state, FIGS. 7 c  and  7   d  show it opened. As apparent from the sectional views  7   a  and  7   c , the two housing halves are pivotally joined by a hinge  46 . When closed (FIG. 7 a ), a snap lock  45  of one housing half engages the other housing half. As a further variant, the hinge  46  may be replaced by a flexible element or by another snap lock.  
         [0034]    It is pointed out that the biopsy needle and the canula and also the spring force storage structure should not comprise any magnetic or electrically conductive material. Rather, they may consist of plastic, which may be fiber reinforced or they may consist of a ceramic material.