Abstract:
An assembly for taking a biopsy sample from a site within the body of a patient includes a housing that is positioned over the bedside table of a patient and contains a biopsy actuator assembly used to propel the needles. The biopsy actuator includes a base-frame receiving a cannula slide and a stylet slide, each slide containing a needle holder for propelling the needles with the aid of one spring each. An electrical magnet-triggering device is provided for releasing the stylet slide, which in turn is adapted during the final phase of its propulsion to release the cannula slide. The housing fits to a needle assembly including a flexible guide tube, a flexible cannula and a stylet. The assembly further includes an electrocautery element and a mechanism for adjusting the forward speed and the depth of invasion of the needles.

Description:
FIELD OF INVENTION 
     This invention relates generally to a biopsy instrument; a device for removing a sample of tissue from a human being or an animal. More particularly, the invention relates to an automated biopsy instrument in which an outer cannula is driven over an inner stylet to obtain the tissue sample. 
     BACKGROUND OF INVENTION 
     The procedure known as biopsy, or the removal of samples of human and animal internal tissue, has been for many years a favored method for the nonsurgical diagnosis of tissue. Using biopsy needles one can take out samples from deeply located organs, such as the liver or the kidneys. This kind of sampling, is usually carried out in such a way that a doctor inserts a needle assembly through the skin and to the desired sampling location. Several kinds of biopsy needles are employed to biopsy the internal organs. One of the most commonly used needle assemblies comprises a slidably provided inner needle within a hollow outer needle. Using this kind of instrument, sampling has been performed in a two-step manual technique in which the outer hollow cutting cannula telescopically receives the inner stylet which is slidable between retracted and extended positions relative to the cannula. The sylet contains a specimen receiving slot near its sharpend distal end. In performing the first step of the technique, the physician places the tip of the needle (with the stylet retracted inside the cannula) against the tissue mass to be sampled and manually drives the stylet forward into the tissue mass. To carry out the second step, the physician manually drives the cutting cannula forwardly over the stylet, thereby severing a tissue sample and retaining it within the stylet slot inside the cannula&#39;s hollow interior. Then the entire needle assembly containing the collected tissue sample is withdrawn, whereafter the sample can be taken out and analyzed. 
     Examples of manually operated biopsy needles of this general type are disclosed in U.S. Pat. No. 4,700,014, issued Jul. 15, 1986 to D. Beraha for “Transrectal Prostate Biopsy Device and Method”, and U.S. Pat. No. 3,477,423, issued Nov. 11, 1969 to L. K. Griffith for “Biopsy Instrument”. Actually many physicians utilize a TRU-CUT® biopsy needle available from Travenol Laboratories, Inc. of Deerfield, Ill. that is described in above mentioned U.S. Pat. No. 3,477,423 to Griffith. 
     Such manually operated two-step devices are awkward to manipulate, and the tissue samples obtained may often be unsatisfactory. The depths to which the stylet and the cannula are driven into the tissue mass must be carefully controlled for accuracy and efficiency. Caution is required, as well, in applying the force with which the stylet and the cannula are plunged forward. Too little force may not sever the tissue sample from the mass. Too much force may cause unnecessary damage to the surrounding vital tissues. 
     Several automated biopsy instruments have been invented to improve the manual procedure and make it easier. The inventive idea resides in placing the needle assembly in a box, in which box there are provided propelling means for propelling the outer and/or inner needles, such that they carry out the above mentioned coordinated movements when the needle assembly has been located to the correct sampling position in the body. The needles are brought to carry out the desired movements in that the operator actuates a release mechanism outside of the box. The example of the automated devices are seen in U.S. Pat. No. 4,767,684, issued May 26, 1987 to H. G. Leigh for “Biopsy Device”. It discloses a movable stylet telescopically received in a hollow movable cannula, both the stylet and the cannula being mounted to hubs within a pistol-style grip. In use the stylet is first manually advanced into the tissue and the cannula is then driven over the stylet by depressing a trigger. 
     A similar instrument designed by D. N. Mehl, through U.S. Pat. No. 4,733,671, issued Mar. 29, 1988, includes a pistol-style squeezable hand grip for single hand operation. A spring tensioned sliding cannula, including a configured cutting edge, actuates by a squeeze trigger and cam arrangement to slide over a fixed position stylet for entry into a tissue sample area. 
     Another automated device is found in U.S. Pat. No. 4,799,154, issued Oct. 13, 1987 to P. G. Lindgren for “Tissue Sampling Device”. It is composed of a mechanism in which a release button is depressed to cause a spring-loaded stylet to be advanced into the tissue mass. The forward movement of the stylet also triggers the delayed release of a spring-loaded outer cannula, which slides over the stylet to sever the tissue sample. 
     U.S. Pat. No. 4,924,878, issued May 15, 1990 to J. E. Nottke for “Actuating mechanism for biopsy needle ” and U.S. Pat. No. 4,958,625, issued Sep. 25, 1990 to J. S. Bates for “Biopsy needle instrument”, disclose two other automated devices with sequential movement of the needles. 
     In any event, the various automated biopsy instruments presently known tend to be heavy and difficult to manipulate. Such limitations diminish the physician&#39;s control over the instrument and the precision with which biopsies may be performed. These instruments may be subject to inadvertent movement or torque which may, in turn, subject the patient to unnecessary trauma and risk. 
     Extensive bleeding can occur as a result of tissue resecting, which can lead to dangerous bleeding and complications. The idea of creating this device arrose after a complicated liver biopsy procedure. The patient developed exsanguinating blood loss through the peritoneum which led to an emergency laparatomy. This complication might be seen in tissue sampling of the visceral organ and is especially encountered in patients with bleeding diathesis. In an effort to remedy these problems, various techniques have been developed. For example, U.S. Pat. No. 3,598,108, issued Aug. 10, 1971 to K. Jamshidi for “Biopsy technique and biopsy device”, discloses a biopsy technique and device involving the insertion of a biopsy needle into the tissue from which the specimen is to be taken, the needle having a sleeve member and the stylet therein, the stylet being removed and the biopsy being collected in the sleeve which is also thereafter removed. A heat transfer means such as a microcauter or a cryoprobe is inserted through the needle to project from the distal end thereof, which serves to cauterize the biopsy track as the needle and heat transfer means are removed as a unit. 
     In addition, U.S. Pat. No. 5,928,163, issued Jul. 27, 1999 to T. W. Roberts for “Biopsy sampler”, discloses a “hot” biopsy procedure, using surgical forceps in which the jaws are electrodes (bipolar or monopolar). After the tissue sample is resected, the forceps are brought in contact with tissue remaining at the resecting site and RF energy is applied to the forceps to cause current to flow (i.e., cauterization) through the resecting site tissue to coagulate the tissue and stop the bleeding. Often, RF energy is applied to the forceps during resecting to help cut the tissue sample as well. 
     U.S. Pat. No. 5,810,806, issued Sep. 22, 1998 to M. A. Ritchart for “Methods and devices for collection of soft tissue”, employs a combination of an electrosurgical cutting and a vacuum retrieving element, for sampling tissues. 
     U.S. Pat. No. 5,607,389, issued Mar. 4, 1997 to Edwards, et al. for “Medical probe with biopsy stylet” discloses several instruments for tissue collection. One of those embodiments includes a biopsy knife device in conjunction with an electromagnetic emitter for selective tissue sampling and electromagnetic heat ablation, or both. 
     U.S. Pat. No. 6,036,656, issued Mar. 14, 2000 to Slater, et al. for “jaw assembly having progressively larger teeth and endoscopic forceps instrument incorporating same” shows a design of an endoscopic forceps coupled to an electrocautery voltage supply for electrocoagulation of the biopsied tissue. Also U.S. Pat. No. 5,458,598, issued Oct. 17, 1995 to Feinberg for “cutting and coagulating forceps” discloses another type of forceps coupled with an electrocautery device for coagulating tissue after taking the biopsy sample. 
     All of these patents, incorporated herein by reference, and others, disclose typical prior art techniques and apparatus for gathering and removing a biopsy sample of tissue for further examination and review by a trained professional. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention is a further improvement in a biopsy sampling instrument, which is specially suited for viseral organ biopsies. Through the use of novel pneumatic controlling structure combined with electrocautery coagulation, the phsician can take out samples from deeply located organs easier and safer. 
     In one aspect, the invention features an assembly for taking a biopsy sample from a site within the body of a patient. The assembly includes a housing, which can be placed over a bed-side table and contains the biopsy needle actuator, a connection port and internal switches for appliance of an electrocautery device, a connection port and an external pedal switch for firing the actuator and a connection to the proximal end of a biopsy needle assembly. This housing not only provides the driving force for moving the stylet and the cannula forward in sequential manner, but also, it draws the needles back in to their initial (resting) position within the guide tube, after tissue sampling. 
     The needle apparatus includes a flexible probe that is composed of three components. A flexible plastic guide tube, which will be placed in the hand of the physician and can be guided to a point from which a sample is required. A moving cannula is telescoped within the guide tube and a notched sampling stylet is telescoped within the cannula. The tip of the stylet projects slightly from the distal end of the guide tube in percutaneous types of the needle to permit an easy penetration of intervening tissue by the sharpend tip of the sylet (e.g. subcutaneous tissue) prior to sampling. Indeed this penetration is not necessary in endoscopic type. 
     From another aspect, the employment of an electrocautery element in one preferred embodiment serves to cauterize the biopsy track before the needle is removed from the biopsied tissue after biopsy taking. Accordingly, the metal cannula and stylet are connected to a monopolar electrocautery device and the current is applied just after severing the tissue by forward movement of the cannula over the stylet in the tissue. Synchronizing the electrocautery appliance with the biopsy taking procedure produces electrocoagulation in the biopsy track before the needles are withdrawn. The electrical current applied to the surrounding tissue will not affect the sample tissue inside the hollow cannula due to good electrical and heat dissipation of the metal needles. 
     The advantages of the novel Automated Hot Biopsy Needle and Device over previous automated biopsy instruments include: 
     1. The housing of the majority of automated biopsy devices are grasped during the biopsy procedure. Therefore it is difficult to manipulate them especially in precise sampling. In this invention, the probe rather than housing would be grasped and manipulated by the physician, accordingly it would be easier for a physician to handle and manipulate a flexible probe especially in those situations that require high precision. 
     2. The biopsy needle actuator is fired by a pedal switch. This not only decreases the inadvertent movement of the needle location during biopsy taking, but also allows the physician to hold the probe with one hand while the other hand could be used to guide the probe for better localization (e.g. prostate biopsy) or to hold other instruments (e.g. laparascope or endoscope). 
     3. The present invention also includes a safety mechanism for preventing the accidental firing of the biopsy actuator. The safety mechanism includes an electronic timer based electrical switch on the front panel of the housing. Triggering of the biopsy actuator by firing buttons is only permitted during 20 seconds after pushing of the releasing activator button on the front panel of the housing. This period is also announced by a beeper. 
     4. In automated biopsy needle instruments, manual or spring loaded forward movement of the stylet into the tissue is followed sequentially by the release of spring loaded cannula for core sampling. In these devices the speed of sequential movement of the stylet and the cannula are fixed and relate to the spring force and the structural design of the instrument. The speed of forward movement of the stylet and the cannula can be adjusted in this device according to the tissue consistency. For example the speed of movement could be decreased in soft organs with low elasticity (e.g. liver) to decrease unnecessary damage to the surrounding tissue or inceased in more compact or elastic tissue to decrease the chance of unsatisfactory sampling. 
     5. The depth of biopsy can not be accurately predetermined by the majority of automated biopsy devices. In this technique and device the distance of the invasion of the biopsy needles from surface can be precisely predetermined. 
     6. This biopsy assembly can be used with conventional rigid or flexible endoscopes (i.e. laparascope, pleuroscope or other endoscopic procedures that need deep tissue biopsies). 
     7. Coupling an electrocautery device with the sampling procedure decreases the chance of bleeding complication. This not only decreases the bleeding risk and blood loss in usual biopsy procedures, but also makes the device useful in special circumstances (biopsy in bleeding diathesis or highly vascular organs). 
     Through use of this technique and device, biopsy specimens may be obtained easier, safer and more precisely. It also permits the physician to perform biopsies in patients with high risk of bleeding (e.g. bleeding diathesis, liver cirrhosis) or of those organs that bleed profusely after sampling (e.g. Spleen). 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
     FIG. 1 is an isometric view of the housing of the biopsy actuator containing several buttons, control knobs and a digital display. 
     FIG. 2 is an isometric view of the biopsy actuator inside the housing. 
     FIG. 3 is a cut-away of the biopsy actuator assembly inside the housing, viewed from top. 
     FIG. 4 is an isometric view of a portion of the biopsy actuator to show the details of the cannula slide and its related components. 
     FIG. 5 is an isometric view of a portion of the biopsy actuator to show the details of the stylet slide and its related components. 
     FIG. 6 shows several isometric and two-dimensional views of the cannula slide. 
     FIG. 6A is a left side view of the cannula slide. 
     FIG. 6B is a top view of the cannula slide. 
     FIGS. 6C &amp; 6D are two isometric views of the cannula slide. 
     FIG. 7 shows several isometric and two-dimensional views of the stylet slide. 
     FIG. 7A is a left side view of the stylet slide. 
     FIG. 7B is a top view of the stylet slide. 
     FIGS. 7C &amp; 7D are two isometric views of the stylet slide. 
     FIG. 8 is a cut-away of the biopsy actuator assembly inside the housing, viewed from front. 
     FIG. 9 is a cut-away of the biopsy actuator assembly inside the housing, viewed from back. 
     FIG. 10 shows several isometric and two-dimensional views of the assembly that control the depth of invasion of the biopsy needles inside the biopsied organ. 
     FIG. 10A is an isometric view of the assembly composed of a hollow shaft disposed slidably within a bush that would be fixed to the right side wall of the housing. 
     Extending a cannula flexible shaft from the housing, it passes through said hollow shaft. 
     FIG. 10B is a left side view of said assembly. 
     FIG. 10C is a front side view of said assembly. 
     FIG. 10 d  is an underside view of said assembly. 
     FIG. 11 Shows an isometric view of a portion of the biopsy actuator to show the details of the cannula slide forward speed control assembly and the mechanism for biopsy tissue retrieval after biopsy taking. 
     FIG. 12 shows an isometric view of the biopsy needle assembly, apart from the housing and biopsy actuator. It shows several components of the apparatus including the cannula needle tip, the cannula hub, the stylet needle tip, the stylet hub, guide tube and its nut. 
     FIG. 13 shows several isometric and two-dimensional views of the cannula hub. 
     FIG. 13A is an isometric view of the cannula hub. 
     FIG. 13B is a front view of the cannula hub. 
     FIG. 13C is a top view of the cannula hub. 
     FIG. 14 shows several isometric and two-dimensional views of the stylet hub. 
     FIG. 14A is an isometric view of the stylet hub. 
     FIG. 14B is a front view of the stylet hub. 
     FIG. 14C is a top view of the stylet hub. 
     FIG. 15 shows several two-dimensional views of the tip of the biopsy needle assembly. It shows the tip of the cannula and the stylet needles in isolated form and during several stages of the biopsy procedure. 
     FIG. 15A is a side view of the tip of the stylet needle. 
     FIG. 15B is a side view of the tip of the cannula needle. 
     FIG. 15C is a side view of the tip of the needle assembly in resting phase before initiation of the biopsy procedure. The cannula needle covers the stylet needle and only the piercing tip of the stylet needle is exposed. 
     FIG. 15D is a side view of the tip of the needle assembly during the biopsy procedure. The stylet needle is protruded from the tip of the cannula needle. 
     FIG. 15E is a side view of the tip of the needle assembly during the biopsy procedure. The cannula needle is covering the protruded stylet needle. At this time the cutting tip of the cannula needle is severing the tissue sample from the patient&#39;s body and holding the severed sample in the tissue sampling notch of the stylet needle. 
     FIG. 15F is a side view of the tip of the needle assembly during the biopsy procedure. The cannula needle covers substantially completely the protruded stylet needle. By the time the cutting tip of the cannula needle reaches the end of its journey over the stylet needle, the severed tissue sample from the patient&#39;s body is held in the tissue sampling notch of the stylet needle. 
     FIG. 16 shows several isometric views of the tip of the needle assembly. It shows the tip of the guide tube, the cannula and the stylet needles in several stages of the biopsy procedure. 
     FIG. 16A is an isometric view of the tip of the needle assembly (endoscopic type) in resting phase before initiation of the biopsy procedure. 
     FIG. 16B is an isometric view of the tip of the needle assembly (percutaneous type) in resting phase before initiation of the biopsy procedure. 
     FIG. 16C is an isometric view of the tip of the needle assembly during the biopsy procedure. The stylet needle protruded from the tip of the cannula needle and guide tube. 
     FIG. 16D is an isometric view of the tip of the needle assembly during the biopsy procedure. The cannula needle is protruding from the tip of the guide tube covering the protruded stylet needle. At this time the cutting tip of the cannula needle is severing the tissue sample from the patient&#39;s body and holding the severed sample in the tissue sampling notch of the stylet needle. 
     FIG. 16E is an isometric view of the tip of the needle assembly during the biopsy procedure. The cannula needle is protruded from the tip of the guide tube to cover substantially the protruded stylet needle. By the time the cutting tip of the cannula needle reaches the end of its journey over the stylet needle, the severed tissue sample from the patient&#39;s body is held in the tissue sampling notch of the stylet needle. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Automated Hot Biopsy Device is made up of several components: 
     A—Housing: As it is depicted in FIG. 1, the housing  10  is composed of a cubic box which contains several buttons and control knobs on its front panel. It can be placed over a patient&#39;s bed side table for easy access. The components include: 
     Main power switch  11  that turns the instrument on/off. 
     Electrocautery switch  130  that turns the electrocautery current on/off during biopsy procedure. Using this switch, it would be possible to perform biopsy procedure with or without electrocautery current coupling, respectively. 
     Releasing activator button  13 . Pushing of this button permits the biopsy actuator to be triggered by firing button  14  or specimen retrieval button  15  within twenty seconds. This interval will be announced by a beeper which is positioned inside the housing. This button is part of the safety mechanism that prevents inadvertent firing of the biopsy needle by pedal firing button  19 , firing button  14  or specimen retrieval button  15  on the front panel of the housing  10 . 
     Firing button  14 . Pushing of this button within 20 seconds of pushing of the releasing activator button  13  results in triggering of the biopsy actuator  30 , which results in (sequential) movement of the stylet needle  129  and the cannula needle  119  to perform biopsy procedure. This button is equivalent to pedal firing button  19 . 
     Specimen retrieval button  15 . Pushing of this button within 20 seconds of pushing of the releasing activator button  13  results in slow protrusion of the stylet needle  129  for retreival of the specimen from the stylet tissue collecting slot  127 . Releasing of this button results in returning of the stylet needle  129  to its primary position inside the cannula needle  119 . 
     The stylet and cannula forward speed control knob  16  controls the forward movement speed of the stylet needle  129  and the cannula needle  119  inside the tissue during the biopsy procedure. Turning this knob will adjust the valves  75  &amp;  65  that control the passage of outlet compressed air, from speed controlling cylinders. 
     Withdrawal lag time control knob  17 . This control knob adjusts the lag time for appliance of the electrocautery current to the biopsy track that starts just after severing and collecting of the tissue specimen by the cannula needle  119  before withdrawal of the needles in to the guide tube. The duration of lag time together with the type and magnitude of the electrocautery current can determine the extent of the electrocoagulation. 
     Depth of needle invasion control knob  140 . This control knob adjusts the depth of invasion of the stylet tip  128  and the cannula cutting tip  118  within the tissue. This is done by changing the position of the guide tube proportional to the cannula and the stylet needles  119  &amp;  129 . Moving guide tube  23  in proportion to the cannula flexible hollow shaft  110  and the stylet wire  120  results in more or less protrusion of the cannula needle  119  and the stylet needle  129  from the distal end of the guide tube  23 . 
     Digital display  18  shows the necessary information about the device action and condition. It may show presence or absence of electrocautery coupling, readiness of biopsy actuator for firing, specimen retrieval, forward speed of the stylet needle  129  and the cannula needle  119  and withdrawal speed of the needles. 
     Pedal firing button  19  and its cable, which is connected through the back wall of the housing  10 , is a counterpart of firing button  14 . Pushing of this button by a physician&#39;s foot results in firing of the biopsy actuator  30  within permited interval (20 seconds) that started after pushing of the releasing activator button  13  on the housing  10 . 
     An opening  20  through which, the cannula flexible hollow shaft  110  and the stylet wire  120  can extend from their needle hubs  111  &amp;  121 , is provided on the right wall of the housing  10 . The stylet wire  120  and the cannula flexible hollow shaft  110  pass through a hollow shaft  21  that secure to the proximal end of the guide tube  23  via guide tube nut  24 . The stylet wire  120  and the cannula flexible hollow shaft  110  are disposed within guide tube  23  and telescoping with respect thereto. 
     There are several cable connections to the housing  10 . One of those connect housing to the pedal firing button  19 . The other two cables connect housing  10  to the electricity power supply  12  and electrocautery device  131 . 
     B—Biposy acuator assembly: FIG. 2 is an isometric view of the housing where the biopsy actuator  30  is disposed. In this view the relation of the biopsy actuator  30  and the housing  10  is obvious. The biopsy actuator  30  is composed of several components. 
     The biopsy actuator base-frame is made up of  2  cylindrical solid shafts  32  &amp;  34  that act as sliding guideways for movement of the cannula slide  40  and the stylet slide  50 . These guideways are kept parallel with the support of three fixed jaws  31 ,  33 ,  35 . The left  35 , middle  33  and right  31  fixed jaws attach securely to the left, middle and right end of the guideway shafts respectively. The cannula slide  40  moves easily on the guideway shaft back and forth between the right and middle fixed jaws  31 ,  33 . The stylet slide  50  moves easily on the guideway shafts back and forth between the middle and left fixed jaws  33 ,  35 . The stylet speed control cylinder  70  and the cannula speed control cylinder  60  are seen on the left and right side of the biopsy actuator  30 . The stylet and the cannula cocking electromotors  90 ,  100  are seen on the front left and right of the biopsy actuator  30  respectively. 
     FIG. 3 is a cut-away of the biopsy actuator assembly veiwed from top. It shows the breach mechanism for firing the biopsy needle assembly to take a biopsy sample. The breach mechanism includes a cannula slide  40  for propelling the cannula needle  119  and a stylet slide  50  for propelling the stylet needle  129  during taking of a biopsy specimen. 
     FIG. 4 is a magnified portion of the biopsy actuator that shows more details of the cannula slide and its related components. As it is depicted in this isometric veiw, the cannula slide  40  is biased in a forward position by a helical spring  43 . The cannula slide  40  has a recess area  41  and a cover  42  for receiving the needle hub  111  of the cannula and a pair of lumens  46 , 47  for receiving guide-way shafts  32 , 34 . 
     FIG. 5 is a magnified portion of the biopsy actuator that shows more details of the stylet slide and its related components. As it is depicted in this isometric veiw, the stylet slide  50  is biased in a forward position by a helical spring  53 . The stylet slide  50  has a recess area  51  and a cover  52  for receiving the needle hub  121  of the stylet and a pair of lumens  56 , 57  for receiving guide-way shafts  32 , 34 . 
     FIG. 6 further depicts various aspects of the cannula slide from several perspectives. FIG. 6A is a front view, FIG. 6B is a top view, and FIGS. 6C and 6D are two isometric views of the cannula slide. 
     FIG. 7 further depicts various aspects of the stylet slide from several perspectives. FIG. 7A is a front view, FIG. 7B is a top view, and FIGS. 7C and 7D are two isometric views of the stylet slide. 
     The biopsy actuator also includes a cocking mechanism for retracting and retaining the cannula slide  40  against the force of compressed spring  43  and for retracting and retaining the stylet slide  50  against the force of compressed spring  53 . As shown in FIGS. 3,  4  and  5  the cocking mechanism includes an electromotor  100  and its gear boxes that retract the cannula slide  40  by a mechanical drive provided through a rack  103  and pinion  102  transmission drive  101 . Another electromotor  90  and its gear boxes retract the stylet slide  50  by a mechanical drive provided through a rack  93  and pinion  92  transmission drive  91 . Rotating of the cannula pinion  102  induced by its electromotor results in backward (left) movement of the gear rack  103  and attached cannula slide  40  against the bias of spring  43  to cock the cannula slide  40 . The cocking mechanism also includes two cannula retaining arms  44  for retaining the cannula slide  40  in a cocked position against compressed spring  43 . The cannula retaining arms  44  have hooked ends  45  which hook over the middle fixed jaw  33  of the biopsy actuator base-frame to retain the cannula slide  40  in a cocked position. 
     Rotating of the stylet pinion  92  induced by its electromotor results in backward (left) movement of the gear rack  93  and attached stylet slide  50  against the bias of the stylet spring  53  to cock the stylet slide  50 . The cocking mechanism also includes two stylet retaining arms  54  for retaining the stylet slide  50  in a cocked position against compressed spring  53 . The stylet retaining arms  54  have hooked ends  55  which hooks over the left fixed jaw  35  of the biopsy actuator base frame to retain the stylet slide  50  in a cocked position 
     The biopsy actuator also includes a firing mechanism for firing the biopsy actuator to release the cannula slide  40  and the stylet slide  50  from their cocked positions, thereby propelling a stylet wire  120  and the cannula flexible hollow shaft  110 . This movement results in propelling of the stylet needle  129  and the cannula needle  119  of the biopsy needle assembly to take a biopsy sample of tissue in a patient&#39;s body. Referring to FIG. 1, the firing mechanism includes a releasing activator button  13  and a firing button  14  on the front panel of the housing  10 . In addition, a pedal firing button  19  is a counter part of firing button  14  on the housing  10 . Pushing of the releasing activator button  13  permits the biopsy actuator to be fired whithin 20 second by pushing of the firing button  14  or its counterpart pedal firing button  19 . Pushing of the electrical firing button  14  during the permited interval results in the activation of the releasing assembly  80 . FIGS. 8 &amp; 9 are a cut-away of the biopsy actuator assembly veiwed from front and back. These figures with an isometric view provided in FIG. 5 better show the releasing assembly  80 . Activation of the releasing assembly  80  results in retraction of the core shaft  81  into the electromagnet coil  82  due to magnetic field strength. The core shaft  81  is joined to the releasing lever  83  on its end and its movement results in pivot of the releasing lever  83  on its middle axis pin  84  that is situated on the left fixed jaw  35  of the base frame. This pivot movement causes the other end of the releasing lever  83  to move toward the hooked end  55  of the retaining arms  54  of the stylet slide  50 . Pushing on the hooked end  55  of the stylet retaining arms  54  causes the hooked ends  55  of the retaining arms  54  to move toward each other and lift from the left fixed jaw  35  and release the stylet slide  50  from a cocked position and allows spring  53  to expand, thereby propelling the stylet slide  50  to a forward position. The projections  86  on the stylet slide  50  eventually strike the hooked ends  45  of the cannula retaining arms  44 , causing the hooked ends  45  to lift, thereby releasing the cannula slide  40  from a cocked position and allowing spring  43  to expand, thereby propelling the cannula slide  40  forward (right) in phased sequence. 
     The biopsy actuator  30  also includes a safety mechanism for preventing the accidental firing of the biopsy actuator  30 . Referring to FIG. 1, the safety mechanism includes an electronic timer based electrical switch  13  on the front panel of the housing. Inadvertent pushing of the firing button  14  on the front panel of the housing or pedal firing button  19  will not result in actuating of the biopsy actuator. Pushing of these buttons can only fire the actuator in permitted period that starts just after pushing of the releasing activator button  13 . 
     One embodiment of the invention is directed to the problem of depth of invasion of the needle biopsy. As depicted in FIG. 1, the invention provides a control knob  140  the can change the position of the guide tube  23  in respect to the housing  10 . Because the length of movement of the stylet slide  50  and the cannula slide  40  can not be changed easily, the length of movement of the stylet needle  129  and the cannula needle  119  are constant. However if we change the position of the guide tube  23  in proportion to the housing  10 , the length of protrusion of the tip the stylet  128  and the cannula  118  from tip of the guide tube  29  (depth of the invasion of the needles) could be determined precisely. Refer to FIG. 2, Extending the cannula flexible hollow shaft  110  and the stylet wire from their hubs  111  &amp;  121  through an opening  20  on the right wall of the housing  10 , they pass through a hollow shaft  21  that is coupled to the proximal end of the guide tube  23  by the guide tube nut  24 . The hollow shaft  21  that is coupled to the proximal end of the guide tube  23  on its end, slides within a bush  145  that is fixed to the right wall of the housing  10 . As it is shown in FIG. 10 the linear movement of the hollow shaft  21  inside the bush  145  is provided by a rack and pinion  144  &amp;  146  transmission drive. The underneath aspect of the hollow shaft is shaped in to a rack gear  144  which will be engaged with a pinion  146  that could be turned by turning of the biopsy depth control knob  140 . The biopsy depth control knob  140  connected to the pinion  146  through a joining arm  141 . The pinion rotates on its axis  143 , between two projections provided on the bush  145  and this results in the linear movement of the rack gear  144  on the hollow shaft  21 . The adjustment of the depth of the biopsy specimen is controled within five milimeter percision by a ball and socket  147  &amp;  148  mechanism that is supplied on the upper portion of the bush  145 . This mechanism can make several stops in the journey of the hollow shaft inside of the bush. The distance between each stop is 5 milimeters. The stops are made available by engagement of the grooves  147  on the upper aspect of the hollow shaft  21  to a ball  148  that is pushed in to the grooves by a small coiled spring  149 . These stops not only adjust the depth of the tissue needle invasion precisely, but also prevent unintentional guide tube movement during taking the biopsy specimen. When the biopsy specimen is going to be obtained through a percutaneous route, the piercing tip of the stylet  128  could be protruded slightly from tip of the guide tube  23  by adjusting the biopsy depth control knob  140 , for better penetration of the subcutaneous and other intervenening tissue before firing the biopsy actuator. This is not necessary in endoscopic or laparasopic routes of the biopsy procedure. 
     Yet another embodiment of the present invention addresses the need to control the forward movement speed of the stylet and the cannula. Referring to FIG. 3 the apparatus comprises a 2 speed control cylinder that can control the speed of the movement of the cannula and the stylet slides. The cannula speed control cylinder  60  is seen at the right side of the biopsy actuator  30 . It contains a piston  62  that moves within the cylinder  60  by its connection to the cannula slide  40  through a joining arm  63 . The cylinder includes an outlet  61  that permits exit of the compressed air during the movement of the piston  62 . This outlet is connected via a hosepipe  64  to a regulator valve  65  that can be adjusted by a control knob  16  on the front panel of the housing  10 . The stylet speed control cylinder  70  is seen at the left side of the biopsy actuator  30 . It contains a piston  72  that moves within the cylinder  70  by its connection to the stylet slide  50  through a joining arm  73 . The cylinder includes an outlet  71  that permits exit of the compressed air during the movement of the piston  72 . This outlet is connected via a hosepipe  74  to the regulator valve  75  that can be adjusted by a control knob  16  on the front panel of the housing  10 . 
     Another aspect of the present invention involves the automated withdrawal of the biopsy needles from the sampled tissue. This withdrawal is performed while the biopsy actuator is being cocked by the electromotors  90  &amp;  100  drive. Initiation of this withdrawal movement is started after a lag time that permits the appliance of the electrocautery current. This lag time would be started just after severing and collecting of the tissue by the cannula needle  129  and would be terminated just before initiation of the needle withdrawal. The electrocautery current is applied to the cannula hub  111  at the initiation of the lag time by a micro switch that is activated only when the cannula slide projections  87  strikes the right fixed jaw  31  of the biopsy actuator  30  base-frame. 
     Further aspects of the present invention deal with a mechanism for sampled tissue collection after the biopsy taking. This mechanism is triggered by a specimen retrieval button  15  on the front panel of the housing  10 . This mechanism also includes a safety mechanism for preventing the accidental release of the retrieval button  15 . The safety mechanism includes an electronic timer based electrical switch on the front panel of the housing. Pushing of the retrieval button  15  can only release the stylet slide for tissue retrieval in a permited period (20 seconds) that starts just after pushing of the releasing activator button  13 . Pushing of the retrieval button  15  in the permitted period that would be announced by a beeper, results in activation of the releasing assembly  80 . Activation of the releasing assembly  80  results in retraction of the core shaft  81  into the electromagnet coil  82  and finally results in release of the stylet slide  50  from a cocked position and allows spring  53  to expand, thereby propelling the stylet slide  50  to a forward position just similar to the usual biopsy taking procedure initial stage. The great difference between the tissue retrieval process and the firing process resides in the forward movement speed of the stylet slide. As mentioned above, the stylet forward speed controlling assembly is composed of a piston  72  and a cylinder  70  with an outlet  71 . As it is shown in FIG. 11, the outlet  71  is connected via a hosepipe  74  to the regulator valve  75  that is controled by a control knob  16  on the front panel of the housing  10 . The connecting hosepipe  74  passes through a passageway  76  that can be regulated by the specimen retrieval button  15 . The compressed air might pass through this passageway without any significant resistance only if the button is not pushed. Pushing of the specimen retrieval button decreases the opening diameter of passageway  76  to such an amount that compressed air might pass with significant resistance, therefore decreasing the forward movement speed of the stylet slide  50  significantly. Slow movement of the stylet slide  50  produces a touch rather than a stroke of the stylet slide projection  86  to the hooked end of the cannula retaining arms  45  and this force would be inadequate to release the cannula slide  40  from its cocked position. The result is a smooth protrusion of the stylet needle from the tip of the cannula and guide tube without release of the cannula needle. This allows the physician to collect the biopsied tissue from the stylet needle slot  127 . Releasing of the specimen retrieval button results in activation of the stylet cocking mechanism and backward movement of the stylet slide  50  and the stylet needle  129  to its cocked position. 
     The electrocautery current will be provided from an external electrocautery device that is connected to the housing through a cable  131 . Viewing the FIG. 1 the current can be switched on/off by the electrocautery main switch  130  on the front panel of the housing  10 . This switch  130  permits taking a biopsy with or without electrocautery appliance. An electrical wire connect the electrocautery current from the main switch  130  to a microswitch that is positioned on the right fixed jaw  31  of the base-frame and another electrical wire connect the electrocautery current from the microswitch to an electrode in the cannula slide recess  41 . This electrode is in contact with the cannula hub  111 . Triggering of the microswitch by the cannula slide  40  on termination of its journey on the guideway shafts results in appliance of the electrocautery current to the cannula hub  111  and then to the cannula flexible hollow shaft  110 . This shaft transmits the current to the cannula needle  119  while it is inside the biopsied tissue. The current will pass from the surface of the cannula needle  119  to the surrounding tissue and coagulate the vessels in the biopsy track. Due to good electrical conductivity of the cannula needle  119 , the current will not pass through the biopsied tissue inside the cannula needle. On the other hand, the cannula has conductivity sufficiently high to remove heat from the cannula needle to prevent thermal damage of the tissue inside of the cannula while delivering power to the surrounding tissue to produce coagulation. 
     Although the type and magnitude of the electrocautery current can be determined by changing the setting of the elecrocautery device, another embodiment of the present invention makes it possible to control the duration of electrocoagulation time by adjusting the time interval between termination of the tissue cutting and collecting by the cannula needle  119  and initiation of needle withdrawal. The lag time is controlled by an electronic timer regulated by a control knob  17  on the front panel of the housing  10 . Changing the duration of the lag time, a physician would be able to control the duration of contact of the cannula to the surrounding tissue and therefore determine the degree of electrocoagulation that is necessary for special circumstances. 
     C—Biopsy needle assembly: A biopsy needle assembly is used with the biopsy actuator  30  for taking a biopsy sample of the tissue of interest. FIG. 12 shows the biopsy needle assembly apart from biopsy actuator  30 . At one end of the biopsy needle assembly, there are needle sampling tips for insertion into the patient&#39;s body to obtain the tissue sample. These are the cannula cuting tip  118  and the stylet piercing tip  218 . At the other end are needle hubs  111  and  121  which engage the needle assembly with the biopsy actuator  30 . The cannula hub  111  is made of metal and securely attached to the cannula flexible hollow shaft  110 . It is disposed in a recess  41  in the stylet slide  40 . Further shown in FIG. 13, the cannula hub has a middle groove  112  between two shoulders  113  &amp;  114  that mates a collar in the cannula recess  41  in the cannula slide to secure the hub  111  inside the recess  41 . In addition the asymetric shape of the cannula hub  111  will not allow the hub to rotate within the recess. The cannula hub  111  can be disengaged from the cannula slide  40  easily by opening of the cannula slide cap  42  and removing of the cannula hub  111  from the cannula slide recess  41 . The stylet hub  121  is securely attached to the stylet wire  120  and disposed in a recess  51  in to the stylet slide  50 . FIG. 14 shows the stylet hub has a middle groove  122  between two shoulders  123  &amp;  124  that mates a collar in the stylet recess  51  in the stylet slide  50  to secure the hub  121  inside the recess  51 . In addition the asymetric shape of the stylet hub  121  will not allow the hub to rotate within the recess  51 .The stylet hub  121  can also be disengaged from the stylet slide easily by openning of the stylet slide cap  52  and removing of the stylet hub  121  from the the stylet slide recess  51 . 
     The cannula flexible hollow shaft  110  is a flexible hollow tube preferably formed of coiled stainless steel wire. It is attached securely to the cannula hub  111  on its proximal end and coupled to the cannula needle  119  at the distal end. Upon assembly, the cannula needle  119  and the cannula flexible hollow shaft  110  is inserted through guide tube  23  and is extendable therefrom. When firing the biopsy actuator, the cannula flexible hollow shaft  110  transmits the linear movement of the cannula slide  40  from the cannula hub  111 , at its proximal end to the cannula needle  119  at its distal end. 
     The stylet wire  120  is a flexible stainless steel wire that is disposed within the cannula flexible hollow shaft  110  and telescopes with respect thereto. The proximal end of the stylet wire couples securely to the stylet hub  121  while its distal end is attached to the proximal end of the stylet needle  129 . Upon firing of the biopsy actuator, the stylet wire  120  transmits the linear movement of the stylet slide  50  from the stylet hub  121 , at its proximal end to the stylet needle  129  at its distal end. 
     FIG. 15 shows a two dimensional views of the tip of the biopsy needles, which can be used to take a biopsy sample. The biopsy needles include the cannula needle  119  and the stylet needle  129 . As FIG. 15B shows, the cannula needle  119  is a hollow needle that is disposed inside of the guide tube  23 . Its distal end has a circular cutting tip  118 , which is inserted into the patient&#39;s body during tissue sampling while its proximal end is permanently coupled to the cannula flexible hollow shaft  110  and remains outside of the patient&#39;s body. 
     As FIG. 15A shows, the stylet needle  129  is a solid needle that is disposed inside of the cannula needle  119 . It has a piercing tip  128  on its distal end for piercing tissue inside of a patient&#39;s body during the taking of a biopsy sample. The stylet needle proximal end is coupled permanently to the stylet wire  120  and remains outside of the patient&#39;s body. The stylet needle  129  also has a tissue-sampling slot  127  in which a biopsy tissue sample can be collected. 
     FIG. 16 shows isometric views of the tip of the biopsy needle assembly, which can be used to take a biopsy sample. The biopsy needle assembly is comprised of biopsy needles and the guide tube  23 . The guide tube  23  is a hollow flexible plastic tube that covers the cannula flexible hollow shaft  110 , the cannula needle  119 , the stylet wire  120  and the stylet needle  129 . The guide tube  23  is held in the physician&#39;s hand and can be used to direct the biopsy needle assembly toward the desired direction. It remains outside of the patient&#39;s body during the taking of the biopsy sample. Although the cannula needle  119  and the stylet needle  129  are substantially straight and rigid, the cannula flexible hollow shaft  110 , the stylet wire  120  and guide tube  23  are all made up of flexible material to enable the physician to easily manipulate the direction of the biopsy needle assembly probe. 
     Referring to FIGS. 15C &amp; 16A, the piercing tip  128  of the stylet needle  129  of the biopsy needle assembly is initially in a retracted position substantially within the hollow interior of the guide tube  23 . Upon firing the biopsy actuator  30  (FIGS. 15D &amp; 16C ), the stylet wire  120  is moved relative to the cannula flexible hollow shaft  110  and the guide tube, such that the stylet needle  129  and its piercing tip  128  protrudes from the cannula needle  119  and guide tube end  29  to pierce the tissue of interest with piercing tip  128  and to fill tissue sampling slot  127  with the tissue to be sampled. The cannula flexible hollow shaft  110  is then moved relative to the stylet wire and guide tube (FIGS. 15E &amp; 16D) thereby moving the cannula needle  119  and its cutting tip  118 , down over the tissue sample, which filled the tissue sampling notch  127  of the stylet needle  129 , thereby severing the tissue sample from the patient&#39;s body and holding the severed sample in the tissue sampling notch  127  which ends up substantially completely within the cannula needle  119  (FIGS.  15 F &amp;  16 E). After severing the tissue with the cutting end  118  of the cannula, the electrocautery current is applied to the surrounding tissue through the cannula metal surface while the needle is within the biopsy track. 
     By adjusting the depth of the needle invasion control knob  140  on the front panel of the housing  10 , the physician is able to protrude slightly the piercing tip  128  of the stylet needle  129  from the distal end  29  of the guide tube  23  for performing a biopsy via percutaneous route. (FIG. 16B) This is done for better penetration of the subcutaneous and other intervening tissue and is not necessary in endoscopic or laparasopic biopsy procedures. After penetration of the subcutaneous and other intervening tissue by the piercing tip  128  of the stylet needle  129 , the depth of needle invasion control knob  140  could be adjusted to the desired value before firing the biopsy actuator  30 . 
     In order to collect the biopsied tissue, the stylet needle  129  will be protruded slowly from the cannula needle  119  and the guide tube  23  by pushing of the tissue retreival button  15  on the front panel of the housing and the collected tissue sample can be recovered for analysis. 
     Although the needle assembly of the present invention may be sterilized for reuse, an advantage of the simple structure needle assembly is that it can be made relatively inexpensively and can, therefore, be economically disposed of after a single use, thereby avoiding the cost and complexity of sterilization for reuse. 
     The foregoing description of the invention has been presented for purposes of illustration and description. Further, the description is not intended to limit the variations and modifications commensurate with the above teachings, and the skill or knowledge in the relevant art are within the scope of the present invention. The preferred embodiment described herein above is further intended to explain the best mode known of practicing the invention and to enable others skilled in the art to utilize the invention in various embodiments and with the various modifications required by their particular applications or uses of the invention.