Abstract:
A driver apparatus is provided for use with a biopsy instrument, the driver apparatus including a housing and an insertion mechanism including a carriage movably associated with the housing and adapted to support the biopsy instrument to affect longitudinal movement of at least a portion of the biopsy instrument. A linear motion control mechanism is also included that is adapted to move a tissue cutting element of the biopsy instrument from a first position to a second position relative to a tissue receiving portion of the biopsy instrument. Further, a tissue retract mechanism is included which facilitates removal of a tissue specimen from the biopsy instrument without removing the entire biopsy instrument from a surgical site.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is a continuation application of copending U.S. application Ser. No. 09/252,548 filed Feb. 19, 1999 which claims priority to U.S. Provisional Application Serial No. 60/078,748 filed Feb. 20, 1998 entitled BIOPSY INSTRUMENT DRIVER APPARATUS, the entire contents of which are incorporated by reference.  
     
    
     
       1. TECHNICAL FIELD  
         [0002]    This disclosure relates to an apparatus and method for the biopsy of tissue specimens and, more particularly, to a driver apparatus for biopsy instruments.  
         2. BACKGROUND OF RELATED ART  
         [0003]    It is often necessary to sample tissue in order to diagnose and treat patients suspected of having cancerous tumors, pre-malignant conditions and other diseases or disorders. Typically, in the case of suspected cancerous tissue, when the physician establishes by means of procedures such as palpation, x-ray or ultrasound imaging that suspicious conditions exist, a biopsy is performed to determine whether the cells are cancerous. Biopsy may be done by an open or percutaneous technique. Open biopsy removes the entire mass (excisional biopsy) or a part of the mass (incisional biopsy). Percutaneous biopsy on the other hand is usually done with a needle-like instrument and may be either a fine needle aspiration (FNA) or a core biopsy. In FNA biopsy, individual cells or clusters of cells are obtained for cytologic examination and may be prepared such as in a Papanicolaou smear. In core biopsy, as the term suggests, a core or fragment tissue is obtained for histologic examination which may be done via frozen section or paraffin section. In more recent developments percutaneous techniques have been used to remove the entire mass during the initial procedure.  
           [0004]    Intact tissue from the organ or lesion is preferred by medical personnel in order to arrive at a definitive diagnosis regarding the patient&#39;s condition. In most cases only part of the tissue or lesion need be sampled. The portions of tissue extracted must be indicative of the tissue or lesion as a whole. In the past, to obtain adequate tissue from organs or lesions within the body, surgery was performed so as to reliably locate, identify and remove the tissue. With present technology, medical imaging equipment such as stereotactic x-ray, fluoroscopy, computer tomography, ultrasound, nuclear medicine and magnetic resonance imaging, may be used. These technologies make it possible to identify small abnormalities even deep within the body. However, definitive tissue characterization still requires obtaining adequate tissue samples to characterize the histology of the organ or lesion.  
           [0005]    The introduction of image guided percutaneous breast biopsies offers alternatives to open surgical breast biopsy. With time, these guidance systems have become more accurate and easier to use. Biopsy guns were introduced for use in conjunction with these guidance systems. Accurate placement of the biopsy guns was important to obtain useful biopsy information because only one small core could be obtained per insertion at any one location. To sample the tissue thoroughly, many separate insertions of the instrument are often required.  
           [0006]    Biopsy procedures may benefit from larger tissue samples being taken, for example, tissue samples as large as 10 mm across. Many of the prior art devices required multiple punctures into the breast or organ in order to obtain the necessary samples. This practice is both tedious and time consuming.  
           [0007]    One further solution to obtain a larger tissue sample is to utilize a device capable of taking multiple tissue samples with a single insertion of an instrument. An example of such a device is found in U.S. Pat. No. 5,195,533 to Chin et al. which describes a technique for extracting multiple samples with a single insertion of the biopsy device. Generally, such biopsy instruments extract a sample of tissue from a tissue mass by either drawing a tissue sample into a hollow needle via an external vacuum source or by severing and containing a tissue sample within a notch formed on a stylet. Typical of such devices utilizing an external vacuum source are U.S. Pat. No. 5,246,011 issued to Cailouette and U.S. Pat. No. 5,183,052 issued to Terwiliger. Such devices generally contemplate advancing a hollow needle into a tissue mass and applying a vacuum force to draw a sample into the needle and hold the same therein while the tissue is extracted. These devices require an operator to manually perform some of the separate functions involved in extracting tissue samples. These functions, include, for example, translating the needle within a patient, actuating a cutting mechanism, and actuating a vacuum source.  
           [0008]    When extracting multiple samples with a single insertion of the biopsy device using suction to either draw in tissue or remove the tissue from the body, it is important that reliable samples are extracted for accurate diagnosis. If the operator is required to frequently manipulate and adjust a device to accommodate the several functions, the reliability and integrity of the sample may be compromised.  
           [0009]    Therefore, a continuing need exists for driver apparatus which can reliably introduce biopsy instruments to extract adequate biopsy sample(s) and reduce the number of operations required to be performed by an operator.  
         SUMMARY  
         [0010]    One particular embodiment of the present disclosure provides a surgical biopsy apparatus which includes a driver apparatus for use with a biopsy instrument which includes a plurality of relatively movable elongated members. The driver apparatus includes a housing, an insertion mechanism, a linear control mechanism and a tissue retract mechanism. The driver apparatus may be mounted to an imaging table and may also communicate with a vacuum/controller module.  
           [0011]    The insertion mechanism includes a carriage that is movably associated with the housing. The carriage is adapted to support the biopsy instrument to affect longitudinal movement of at least a portion of the biopsy instrument relative to the housing.  
           [0012]    The linear motion control mechanism is adapted to move a tissue cutting element of the biopsy instrument from a first position to a second position relative to a tissue receiving portion of the biopsy instrument. The tissue cutting element cuts tissue extending into a tissue receiving portion of the biopsy instrument.  
           [0013]    The tissue retract mechanism facilitates removal of a tissue specimen from the biopsy instrument without removing the entire biopsy instrument from a surgical site. The tissue retract mechanism includes a retention member adapted to retain a portion of the biopsy instrument. The tissue retract mechanism further includes a longitudinal guide member which slidably guides the retention member and is disposed relative to the housing in a manner to permit movement of the longitudinal guide member relative to the housing.  
           [0014]    In an alternate embodiment of the present disclosure, a surgical biopsy apparatus is provided which includes a driver apparatus for use with a biopsy instrument which includes a tissue receiving portion and a cutting element. The driver apparatus includes a housing, an insertion mechanism and a cutting element controller assembly. The insertion mechanism is adapted to support a biopsy instrument thereon. The insertion mechanism includes a carriage that is movably associated with the housing. The carriage is movable from a retracted position to an advanced position to affect longitudinal movement of the biopsy instrument. The cutting element controller assembly is operatively disposed on the housing. The controller assembly includes a linear motion control mechanism, a motor and an enabling switch.  
           [0015]    The linear motion control mechanism is adapted to move a tissue cutting element of the biopsy instrument from a first position to a second position relative to a tissue receiving portion of the biopsy instrument. The tissue cutting element cuts tissue extending into a tissue receiving portion of the biopsy instrument.  
           [0016]    The motor is operatively associated with the cutting element when the biopsy instrument is mounted on the biopsy instrument driver apparatus. The motor facilitates movement of the cutting element relative to the tissue receiving portion.  
           [0017]    The enabling switch is disposed relative to the linear motion control member and electrically connected to the motor. Movement of the linear motion control member from the second position to the first position causes the switch to activate the motor.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]    Various embodiments are described herein with reference to the drawings, wherein:  
         [0019]    [0019]FIG. 1 is a perspective view of one embodiment of a percutaneous biopsy instrument driver apparatus constructed in accordance with the present disclosure;  
         [0020]    [0020]FIG. 2 is a perspective view from a reverse angle perspective to that of FIG. 1 which shows detachably mounting a cover onto the biopsy instrument driver apparatus;  
         [0021]    [0021]FIG. 3 is an exploded perspective view of the biopsy instrument driver apparatus embodiment of FIG. 1;  
         [0022]    [0022]FIG. 4 is a cross-sectional view taken along section line  4 - 4  of FIG. 3;  
         [0023]    [0023]FIG. 5 is an enlarged perspective partial side view of a distal portion of a drive assembly of FIG. 1;  
         [0024]    [0024]FIG. 6 is an enlarged perspective partial side view of a distal portion of the drive assembly showing the reverse angle of FIG. 5;  
         [0025]    [0025]FIG. 7 is an exploded perspective view of some of the principal components of a cutting element control assembly of the biopsy instrument driver apparatus shown in FIG. 1;  
         [0026]    [0026]FIG. 8 is an enlarged perspective view of a distal portion of a biopsy instrument;  
         [0027]    [0027]FIG. 9 is an enlarged side partial cross-sectional view which shows a cutting element controller assembly in a fully retracted position;  
         [0028]    [0028]FIG. 10 is an enlarged cross-sectional view showing fluid flow lines of suction being applied and a tissue mass being drawn into a lateral tissue receiving opening formed in the biopsy apparatus;  
         [0029]    [0029]FIG. 11 is a side view in part cross-section of the distal portion of the biopsy instrument driver apparatus, showing the cutting element controller assembly in a fully forward position;  
         [0030]    [0030]FIG. 12 is an enlarged cross-sectional-view of the indicated area of detail as shown in FIG. 11; and  
         [0031]    [0031]FIG. 13 is an enlarged cross-sectional view showing a knife tube being rotated and advanced distally to sever a tissue mass into the lateral opening in the biopsy apparatus shown in FIG. 1.  
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0032]    Referring now in specific detail to the drawings in which like reference numerals identify similar or identical elements throughout the several views, and initially to FIG. 1, one embodiment of an instrument driver biopsy apparatus is shown generally as apparatus  24 . Apparatus  24  is adapted to removably retain and operate a biopsy instrument such as biopsy instrument  22 . Apparatus  24  may communicate with a vacuum/controller module (not shown), which provides a vacuum source, and is mountable to a medical imaging apparatus (not shown), such as, for example, stereotactic x-ray, fluoroscopy, computer tomography, ultrasound, or other suitable imaging modalities.  
         [0033]    Referring to FIGS.  1 - 3 , biopsy instrument  22  includes three main tubular components supported by a housing  26 . Biopsy instrument  22  is, preferably, in the form of a disposable loading unit which is adapted for removable attachment to apparatus  24  (described hereinbelow). It is contemplated that biopsy instrument  22  may be of permanent fixture type. Biopsy instrument  22  includes an insertion end portion  27  configured and dimensioned for percutaneous introduction into a patient (not shown), for example, into the tissue of a compressed breast. Insertion end portion  27  extends from a distal end  38  of housing  26 . A vacuum hub  29  is removably connected to a proximal end  31  of housing  26 .  
         [0034]    Biopsy instrument  22  includes a vacuum tube  28  having a sharpened distal penetrating end  30  and a tissue receiving portion, for example, tissue basket  32  (shown in FIG. 9) adjacent to distal penetrating end  30 . Vacuum tube  28  is an innermost component of biopsy instrument  22  which is introduced into a target tissue mass  122  (shown in FIGS. 10 and 13) of a patient. Referring to FIGS.  1 - 3 , the vacuum/controller module provides a vacuum source which interfaces with vacuum hub  29  through a first vacuum port  40  communicating suction to an area adjacent tissue basket  32  to draw at least a portion of target tissue mass  122  into tissue basket  32 .  
         [0035]    A tissue cutting element, for example knife tube  34  is rotatably disposed about vacuum tube  28 . Knife tube  34  is configured to advance distally around the outside of vacuum tube  28  while rotating, in order to sever a target tissue portion  136  (shown in FIG. 13) from target tissue mass  122  (shown in FIGS. 10 and 13), as will be discussed hereinbelow. Once target tissue portion  136  is severed, vacuum tube  28  is retracted within knife tube  34  to remove the sample.  
         [0036]    Biopsy instrument  22  also includes an outer tube  36  which is removably attached to distal end  38  of housing  26  for longitudinal sliding relative thereto. Outer tube  36  is, preferably, transparent to x-rays and maintains position of a portion of insertion end portion  27  inside targeted tissue mass  122 , as biopsy instrument  22  and knife tube  34  are retracted to take an x-ray of the biopsy site.  
         [0037]    A second vacuum port  42  is attached to distal end  38  of housing  26  of biopsy instrument  22  providing a second interface with the vacuum/control module. It is contemplated that apparatus  20  may interface with the vacuum/controller module at multiple ports. Second vacuum port  42  aspirates fluid from the biopsy site into a disposable canister provided on the vacuum/controller module (not shown). An example of a biopsy instrument similar to biopsy instrument  22  and a more detailed explanation of the components and method of operation are disclosed in pending application Ser. No. 09/040,244 entitled “Biopsy Apparatus and Method” to Farascioni et al. filed on Feb. 20, 1998, the entire contents of which are hereby incorporated by reference.  
         [0038]    As shown in FIGS.  1 - 3  biopsy instrument  22  is mounted to drive apparatus  24 . Drive apparatus  24  is configured and dimensioned for attachment to an instrument positioning stage of a stereotactic imaging apparatus (not shown). Examples of stereotactic imaging apparatus which are used to perform biopsy procedures are commercially available from LORAD Corporation of Danbury, Conn. or from Fischer Imaging Corporation of Denver, Colo. Alternatively, apparatus  24  may be adapted to fit on or interact with other suitable medical imaging apparatus.  
         [0039]    In FIGS.  1 - 3 , drive apparatus  24  includes a linear motion control mechanism such as knife driver subassembly  44 , a piercing subassembly  46  which includes an insertion mechanism, an electrical subassembly  48  and a housing  50 . Piercing subassembly  46  provides an operator of apparatus  20  with the ability to rapidly insert a portion of biopsy instrument  22  into a tissue mass as an alternative to manually translating biopsy instrument  22  into the tissue mass using the translation capabilities of a imaging apparatus.  
         [0040]    Referring to FIGS. 3, 5 and  6 , piercing subassembly  46  includes a carriage such as sled  52  which supports biopsy instrument  22  and knife driver subassembly  44  such that upon firing of driver apparatus  24 , sled  52  is thrust forward by releasing the stored energy of a spring. It is also contemplated that loaded  52  may be fired with other firing modalities such as, for example, pneumatic, hydraulic, etc.  
         [0041]    Upon firing of sled  52 , biopsy instrument  22  is thrust forward so that biopsy instrument  22  pierces tissue for entry into a targeted tissue mass  122  (shown in FIGS. 10 and 13). Preferably, the minimum piercing force should be approximately 20 lbs., although greater forces are contemplated. Upon firing of driver apparatus  24 , biopsy instrument  22  is, preferably, fired a distance of approximately 18-20 mm. It is contemplated that various amounts of force may be applied resulting in variable piercing distances for different degrees of penetration into a tissue mass depending on the biopsy application.  
         [0042]    Referring to FIGS.  1 - 3 , cocking arms  56  are provided, one on each side of drive apparatus  24  to facilitate cocking of piercing subassembly  46  from either side of housing  50 , thereby permitting one handed operation. Cocking arms  56  are manually accessible by an operator to load a spring connected to sled  52  from a relaxed state. Once cocking arms  56  are cocked into place, a spring load is applied to the spring connected to sled  52 . Upon release after loading the spring, cocking arms  56  then freely release and become disengaged with sled  52  and return to a relaxed state. Piercing subassembly  46  may then be fired to rapidly thrust biopsy instrument  22  into targeted tissue mass  122  (shown in FIGS. 10 and 13) so that sharpened distal penetrating end  30  of biopsy instrument  22  is injected into the target tissue or tissue immediately adjacent the target tissue depending on the user&#39;s preference.  
         [0043]    A cocking position sensor  60  is also included that detects whether sled  52  in a cocked position thus disabling the cutting action of knife tube  34  during firing of driver apparatus  24 . Cocking position sensor  60  preferably provides a signal that sled  52  is cocked which will result in deactivation of a motorized rotary driver of knife tube  34 .  
         [0044]    A user operated fire button  62  disposed on the rear surface of housing  50 , releases sled  52  from the cocked position. Fire button  62  is also accessible from either side of housing  50  and permits one handed operation for firing of apparatus  20 .  
         [0045]    Sled  52 , sled position sensor  60  are mounted to a base  64  of housing  50 , as shown in FIGS.  1 - 3 ,  5  and  6 . In FIGS.  1 - 3 , a body portion  66  of biopsy instrument  22  is secured over sled  52  via a snap fit.  
         [0046]    As shown in FIGS. 2 and 3, driver apparatus  24  includes a tissue retract mechanism  68 . Tissue retract mechanism  68  interfaces with biopsy instrument  22  and drive apparatus  24 . Tissue retract mechanism  68  is mounted to housing  50  of drive apparatus  24 . A cover  70 , as shown in FIGS. 1 and 2, covers tissue retract mechanism  68 .  
         [0047]    Referring to FIGS.  2 - 4 , tissue retract mechanism  68  includes a pair of longitudinal guide members, such as, rails  72  which are slidably supported by a pair of mounting flanges extending upwardly from a mounting bracket. A retention member such as slide block  74  supports proximal end of vacuum tube  28 . A pair of indexing knobs  76  are provided, one on each side of slide block  74  to facilitate rotational orientation of tissue basket  32 , i.e., the clock positioning. Slide block  74  is supported on rails  72  for slidable movement within the range of linear translation of a biopsy instrument  22 . As shown in FIG. 4, slide block  74  defines a pair of bores  78  for slidably receiving rails  72 . As shown by arrow A, at least one of rails  72  has a floating feature within bore  78 . In particular, bore  78  is configured and dimensioned to provide a tolerance whereby at least one of rails  72  may freely move within the limits of bore  78 . This floating feature allows slide block  74  to have a range of motion vertically during linear translation of biopsy instrument  22  to prevent binding of slide block  74  during such motion.  
         [0048]    As shown in FIGS.  5 - 7 , driver apparatus  24  includes knife driver subassembly  44  which facilitates linear translation of knife tube  34  of biopsy instrument  22  via a manual operation. Knife driver subassembly  44  includes a motorized driver for rotating knife tube  34  for cutting tissue and provides feedback by way of microswitches that knife tube  34  is in a full forward position or in a fully retracted position. Knife driver subassembly  44  linearly translates knife tube  34  over tissue basket  32  of biopsy instrument  22 .  
         [0049]    Knife driver subassembly  44  is of a rack and pinion gear design and is manually manipulated via a pair of toggle knobs  82 , one on each side of drive apparatus  24  and mountable within housing  50 , while being accessible from both sides thereof permitting one handed operation. Toggle knobs  82  facilitate a range of linear travel of knife tube  34  between a full forward position wherein knife tube  34  completely covers tissue basket  32  but does not extend beyond sharpened distal penetrating end  30 , and a fully retracted position whereby knife tube  34  completely exposes tissue basket  32 .  
         [0050]    As shown in FIG. 7, toggle knobs  82  are attached by a spindle shaft  84  which supports a pinion gear  86 . Pinion gear  86  engages a rack  88 . Rack  88  is attached to cradle  54 . Pins  90  secure rack  88  to cradle  54  which supports knife tube  34  for linear translational movement. Knife driver subassembly  44  also includes arm  100  which supports a proximal microswitch  102  and a distal microswitch  104 . Microswitches  102  and  104  are electrically connected to the drive motor and to the vacuum/controller module. Rack  88  linearly translates between proximal microswitch  102  and distal microswitch  104 . Upon corresponding linear translation of knife tube  34 , signals are transmitted on the status of knife tube  34  between a forward position and a retracted position. Proximal microswitch  102  is attached to arm  100  by pins  106  and distal microswitch  104  is attached to arm  100  by pins  108 .  
         [0051]    Referring to FIGS. 5 and 6, knife driver subassembly  44  includes a first position sensor  114  and a second position sensor  116 . First position sensor  114  detects knife tube  34  in the fully retracted position exposing tissue basket  32 . Second position sensor  116  detects knife tube  34  in the full forward position and covering the entire tissue basket  32 , but not beyond sharpened distal penetrating end  30 . A forward lock  110  is provided to lock knife tube  34  into its full forward position to ensure that a position sensor  114  remains activated when knife tube  34  is fully forward and to maintain position of knife tube  34  in targeted tissue mass  122 , as vacuum tube  28  is retracted to unload a tissue sample from biopsy instrument  22 . Forward lock  110  also maintains knife tube  34  in a full forward position when firing sled  52 . A retracted lock  112 , is provided to lock knife tube  34  into its fully retracted position so that second position sensor  114  remains activated when knife tube  34  is fully retracted.  
         [0052]    Knife tube  34  rotates for cutting a tissue sample by a rotary drive motor of knife driver subassembly  44 . The rotary drive motor actuates in response to signals received from first position sensor  114  and second position sensor  116 . Biopsy instrument  22  is configured and dimensioned to interface with knife driver subassembly  44  by the meshing of a gear formed on knife tube  34  with a gear or gears which are operatively connected to the drive motor. The motor is mounted to knife driver subassembly  44  so that knife tube  34  can be linearly translated while being rotated. The above components of knife driver assembly  44  and the drive motor are mounted to base  64  of knife driver subassembly  44 . First position sensor  114  and second position sensor  116  send signals to electrical subassembly  48 , corresponding to the position of knife tube  34  within its linear translational range of motion between its forward position and retracted position. The drive motor then correspondingly receives start and stop actuation signals from electrical subassembly  48 .  
         [0053]    For biopsy instrument  22  to be properly loaded within drive apparatus  24 , knife driver subassembly  44  must be in the full forward position for proper alignment with a rotary gear (not shown) of biopsy instrument  22  with the motor.  
         [0054]    Driver apparatus  24  further includes electrical subassembly  48  which receives signals corresponding to the status of sled position sensor  60  of piercing subassembly  46  and first position sensor  114  and second position sensor  116  of knife driver subassembly  44 . Upon receiving signals, electrical subassembly  48  transmits signals to a vacuum supply unit which may be in the form of a separate vacuum/controller module (not shown) corresponding to the status of the position sensors for actuation of the vacuum and the drive motor. Electrical subassembly  48  is mounted to base  64  and housed within housing  50 .  
         [0055]    In operation, biopsy instrument  22  is loaded onto driver apparatus  24 . Knife driver subassembly  44  is manipulated to a full forward position, as shown by the position of rack  88  in FIGS. 11 and 12. Knife driver subassembly  44  is in the fill forward position when rack  88  contacts distal microswitch  104 . The full forward position aligns a knife tube gear of biopsy instrument  22  with a drive gear of driver apparatus  24  so that biopsy instrument  22  may snap fit into driver apparatus  24 . Preferably, knife driver subassembly  44  is locked in the full forward position by forward lock  110  until biopsy instrument  22  is properly snap fit, which releases the lock.  
         [0056]    As shown in FIG. 8, sharpened distal penetrating end  30  of biopsy instrument  22  is moved into alignment with the coordinates of target tissue mass  122  by moving an imaging table (not shown) according to, e.g., a stereotactic image. A patient is positioned on the imaging table for a stereotactic image to determine the exact coordinates of target tissue mass  122  of the patient. Biopsy instrument  22  is advanced toward the patient so that tissue basket  32 , which is covered by knife tube  34  during initial insertion into the patient, is inserted into the patient adjacent targeted tissue mass  122 . Advancement of biopsy instrument  22  is accomplished by either manual translation capabilities of the imaging table or, preferably, by firing piercing subassembly  46  of drive apparatus  24 , as previously described.  
         [0057]    Specifically biopsy apparatus  22  is fired into targeted tissue mass  122  by manipulation of firing button  62 . Knife tube  34  is maintained in the full forward position, thus sled position sensor  60  maintains deactivation of the knife rotary drive  
         [0058]    To obtain tissue sample  136 , as shown in FIGS.  8 - 13 , toggle knobs  82  are manipulated so that knife drive subassembly  44  and knife tube  34  are retracted to the fully retracted position, shown by arrow B. In the fully retracted position, rack  88  contacts proximal microswitch  102  actuating first position sensor  114 . First position sensor  114  signals electrical subassembly  48  which in turn signals the vacuum/controller module activating the vacuum source in fluid communication with tissue basket  32 .  
         [0059]    Referring to FIGS. 8 and 10, applied suction draws a portion of targeted tissue mass  122  into tissue basket  32  through a lateral opening  124  of vacuum tube  28 . Suction flow arrows  126  show the direction and location of the force exerted on target tissue mass  122 . The suction force passes through the plurality of holes  128  in vacuum tube  28  to draw tissue sample  136  therein.  
         [0060]    As shown in FIGS.  11 - 13 , knife tube  34  and knife driver subassembly  44  are manually advanced distally by toggle knobs  82  to a full forward position. During this motion, rack  88  breaks contact with proximal microswitch  102  actuating first position sensor  114 , signaling electrical subassembly  48 , thereby activating the knife rotary driver to rotate knife tube  34 . Preferably, the drive motor causes knife tube  34  to rotate at approximately 1200 to 1400 rpm. Rotating knife tube  34  may be further manually advanced over tissue basket  32  to sever targeted in tissue sample  136  held in receiving basket  32  by the vacuum source.  
         [0061]    When tissue sample  136  is enclosed by knife tube  34  suction is no longer needed and may be removed. Once knife tube  34  completes its distal travel, rack  88  correspondingly contacts distal microswitch  104  actuating second position sensor  116 . Second position sensor  116  signals electrical subassembly  48  which signals the rotary driver to slow rotation of knife tube  34  and signals the vacuum/controller module to shut off the vacuum supply. Upon actuation of second position sensor  116  and corresponding slow down of the rotary driver, the rotary driver is deactivated when tissue basket  32  is positioned at a predetermined orientation, for example, a three o&#39;clock or nine o&#39;clock position.  
         [0062]    Once knife tube  34  is fully distally advanced, a locking wheel and indexer  140  (shown in FIG. 2) located on proximal end  31  of biopsy instrument  22  is rotated to a tissue eject position  144  until a lock tab  146  clears housing  26  of biopsy instrument  22 . Vacuum tube  28  is thereby released and permits withdrawal of vacuum tube  28  and, therefore, tissue basket  32  from within knife tube  34 . Once vacuum tube  28  is withdrawn such that tissue basket  32  is adjacent to a discharge opening  148  in knife tube  34 , a tissue removal assist member (not shown) enters into tissue basket  32  such that an inwardly deflected portion of the tissue removal member contacts the proximal end of the severed tissue sample, thereby urging the tissue sample out of the tissue basket.  
         [0063]    Upon completion of the desired amount of sampling, outer tube  36  is moved distally to a position a radiopaque marker  150  (FIG. 1) formed on outer tube  36  in relative alignment with the location of the biopsy site and length of the location where tissue basket  32  has previously aligned. Outer tube  36  may then be detached from biopsy instrument  22  and apparatus  20  translates away from targeted tissue mass  122  of a patient so that the tissue may be imaged without interference from the radiopaque nature of the remaining components of biopsy instrument  22 .  
         [0064]    Upon completion of the imaging, if it is determined that further sampling is desired or necessary, biopsy instrument  22  may be reinserted through outer tube  36  and reconnected with housing  26  of biopsy instrument  22 . Additional sampling may then be taken as previously described above. Additionally, if desired, aspiration may be performed at the biopsy site if there is bleeding. An aspirator vacuum source is connected to vacuum port  42  (FIGS. 1 and 2) and aspiration may be performed with knife tube  34  in any position.  
         [0065]    It will be understood that the various modifications may be made to the embodiments disclosed therein. 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.