Abstract:
A biopsy device and method are provided for obtaining a tissue sample, such as a breast tissue biopsy sample. The biopsy device includes a disposable probe assembly with an outer cannula having a distal piercing tip, a cutter lumen, and a cutter tube that rotates and translates past a side aperture in the outer cannula to sever a tissue sample. The biopsy device also includes a reusable hand piece with an integral motor and power source to make a convenient, untethered control for use with ultrasonic imaging. The reusable hand piece incorporates a probe oscillation mode to assist when inserting the distal piercing tip into tissue. A saline valve positioned by the reusable hand piece communicates a saline supply through the probe assembly to perform saline flush of the cutter tube and outer cannula.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application is related to the co-pending and commonly-owned U.S. patent application Ser. No. 11/198,558 “BIOPSY DEVICE WITH REPLACEABLE PROBE AND INCORPORATING VIBRATION INSERTION ASSIST AND STATIC VACUUM SOURCE SAMPLE STACKING RETRIEVAL” to Hibner et al., filed 8 Aug. 2005, the disclosure of which is hereby incorporated by reference in its entirety. 
     FIELD OF THE INVENTION 
     The present invention relates in general to biopsy devices, and more particularly to biopsy devices having a cutter for severing tissue, and even more particularly to biopsy devices for multiple sampling with a probe remaining inserted. 
     BACKGROUND OF THE INVENTION 
     When a suspicious tissue mass is discovered in a patient&#39;s breast through examination, ultrasound, MRI, X-ray imaging or the like, it is often necessary to perform a biopsy procedure to remove one or more samples of that tissue in order to determine whether the mass contains cancerous cells. A biopsy may be performed using an open or percutaneous method. 
     An open biopsy is performed by making a large incision in the breast and removing either the entire mass, called an excisional biopsy, or a substantial portion of it, known as an incisional biopsy. An open biopsy is a surgical procedure that is usually done as an outpatient procedure in a hospital or a surgical center, involving both high cost and a high level of trauma to the patient. Open biopsy carries a relatively higher risk of infection and bleeding than does percutaneous biopsy, and the disfigurement that sometimes results from an open biopsy may make it difficult to read future mammograms. Further, the aesthetic considerations of the patient make open biopsy even less appealing due to the risk of disfigurement. Given that a high percentage of biopsies show that the suspicious tissue mass is not cancerous, the downsides of the open biopsy procedure render this method inappropriate in many cases. 
     Percutaneous biopsy, to the contrary, is much less invasive than open biopsy. Percutaneous biopsy may be performed using fine needle aspiration (FNA) or core needle biopsy. In FNA, a very thin needle is used to withdraw fluid and cells from the suspicious tissue mass. This method has an advantage in that it is very low-pain, so low-pain that local anesthetic is not always used because the application of it may be more painful than the FNA itself. However, a shortcoming of FNA is that only a small number of cells are obtained through the procedure, rendering it relatively less useful in analyzing the suspicious tissue and making an assessment of the progression of the cancer less simple if the sample is found to be malignant. 
     During a core needle biopsy, a small tissue sample is removed allowing for a pathological assessment of the tissue, including an assessment of the progression of any cancerous cells that are found. The following patent documents disclose various core biopsy devices and are incorporated herein by reference in their entirety: U.S. Pat. No. 6,273,862 issued Aug. 14, 2001; U.S. Pat. No. 6,231,522 issued May 15, 2001; U.S. Pat. No. 6,228,055 issued May 8, 2001; U.S. Pat. No. 6,120,462 issued Sep. 19, 2000; U.S. Pat. No. 6,086,544 issued Jul. 11, 2000; U.S. Pat. No. 6,077,230 issued Jun. 20, 2000; U.S. Pat. No. 6,017,316 issued Jan. 25, 2000; U.S. Pat. No. 6,007,497 issued Dec. 28, 1999; U.S. Pat. No. 5,980,469 issued Nov. 9, 1999; U.S. Pat. No. 5,964,716 issued Oct. 12, 1999; U.S. Pat. No. 5,928,164 issued Jul. 27, 1999; U.S. Pat. No. 5,775,333 issued Jul. 7, 1998; U.S. Pat. No. 5,769,086 issued Jun. 23, 1998; U.S. Pat. No. 5,649,547 issued Jul. 22, 1997; U.S. Pat. No. 5,526,822 issued Jun. 18, 1996; and US Patent Application 2003/0199753 published Oct. 23, 2003 to Hibner et al. 
     At present, a biopsy instrument marketed under the tradename MAMMOTOME is commercially available from ETHICON ENDO-SURGERY, INC. for use in obtaining breast biopsy samples. These devices generally retrieve multiple core biopsy samples from one insertion into breast tissue with vacuum assistance. In particular, a cutter tube is extended into a probe to cut tissue prolapsed into a side aperture under vacuum assistance and then the cutter tube is fully retracted between cuts to extract the sample. 
     With a long probe, the rate of sample taking is limited not only by the time required to rotate or reposition the probe but also by the time needed to translate the cutter. As an alternative to this “long stroke” biopsy device, a “short stroke” biopsy device is described in the following commonly assigned patent applications: U.S. patent application Ser. No. 10/676,944, “Biopsy Instrument with Internal Specimen Collection Mechanism” filed Sep. 30, 2003 in the name of Hibner et al.; and U.S. patent application Ser. No. 10/732,843, “Biopsy Device with Sample Tube” filed Dec. 10, 2003 in the name of Cicenas et al. The cutter is cycled across the side aperture, reducing the sample time. Several alternative specimen collection mechanisms are described that draw samples through the cutter tube, all of which allow for taking multiple samples without removing the probe from the breast. 
     Even given the many advantages of such multiple sample taking core biopsy devices, in certain applications some surgeons continue to use less expensive biopsy devices guided in real time by an ultrasonic system. These simple biopsy systems omit a full function control console that operates the cutter and vacuum assistance. Instead, a manually controlled hand piece advances a cutter by either stored spring force, a constant pneumatic pressure source, or motor power. Then the surgeon activates a cutter motor to effect the tissue sample. Thus, the surgeon is challenged to maintain the biopsy probe at a desired surgical site while manipulating the patient&#39;s breast. 
     Spring-fired core needle biopsy devices rely upon a firing mechanism that thrusts forward a needle and a cutter to penetrate the tissue and to obtain a tissue sample rather than prolapsing tissue into a side aperture of a probe. Frequently, a surgeon may encounter an area of dense tissue that is more difficult to penetrate than the surrounding tissue during core needle biopsy. In particular, the lesion or tissue mass being targeted in the biopsy procedure may be difficult to penetrate, requiring the physician to push the biopsy needle with considerable force and/or speed in an attempt to penetrate the lesion and collect a sample. 
     When encountering such an area of dense tissue, it is common for surgeons using the type of firing core needle biopsy device described above to fire the device in order to penetrate the lesion and obtain a sample. However, due to the length of the firing stroke of such devices, which may be as long as 0.75 inches, it is nearly impossible for the surgeon to control the travel of the needle after firing. Consequently, the long needle stroke may cause uncertainty as to the needle tip location post fire. This may cause the surgeon to obtain a sample from the wrong area. In addition to missing the targeted tissue, long firing strokes may cause the needle to puncture the chest wall or pierce the skin, particularly when the targeted area is near the patient&#39;s chest wall. Even if the skin is not pierced, the long travel of the needle, along with the likelihood that the needle will be pushed off course by the force of the firing stroke, may lead to needlessly increased trauma for the patient. These spring-fired biopsy devices also yield a single sample per insertion, thus limiting the amount of diagnostic and therapeutic treatment that may be achieved without the increased discomfort and tissue trauma from repeated insertions. Based on surgeons&#39; use of the long firing stroke feature of current devices to aid in penetrating tissue lesions, it is clear that the medical community sees the benefit of firing assistance when inserting a probe to the desired location. 
     In commonly-owned and co-pending U.S. patent application Ser. No. 11/035,873, BIOPSY INSTRUMENT WITH IMPROVED NEEDLE PENETRATION to Beckman, et al., filed on Jan. 10, 2005, the disclosure of which is hereby incorporated by reference in its entirety, manual mechanisms are disclosed that impart small reciprocating motions to the probe of a core biopsy device to render assistance in penetrating tissue, yet cutting is performed after the probe is properly positioned, thus avoiding taking samples from the wrong location. Moreover, retraction of a cutter tube between severing samples allows for retrieval of multiple samples without having to reinsert the probe through the skin again. A control system that is tethered to a hand piece of this core biopsy system provides vacuum assistance and other motor control algorithms with numerous clinical and safety features incorporated. Generally, the core biopsy device portion of the system is disposable and the control system is reused. 
     While these multiple sample core biopsy instruments have numerous advantages, it is believed that the diagnostic and therapeutic opportunities of core biopsy procedures would be more widely used if an economical biopsy device without an elaborate control system existed which did not require the disposal of the entire core biopsy device. 
     SUMMARY OF THE INVENTION 
     The present invention addresses these and other problems of the prior art by providing a biopsy device that has a needle with a probe tube defining a cutter lumen, a sample aperture formed in the probe tube, a barrier defining a first fluid passage and a second fluid passage that both distally-terminate at the sample aperture. A motorized mechanism axially translates a cutter tube within the probe tube across the sample aperture to sever tissue prolapsed therein to axially translate the cutter tube. One of the first and second fluid passages is defined within the cutter tube and the other is defined between an outer surface of the cutter tube and an inner surface of the probe tube. Advantageously, a flush valve assembly responds to a flush control and to the distally positioned cutter tube to couple either the first or second fluid passage to a fluid supply while the other is at a lower pressure so that the needle is flushed. Thereby, tissue debris or coagulated blood may be flushed so that repeated tissue samples may be taken without impediment. However, the saline flush is selectively employed at the user&#39;s discretion, providing an economical reduction in the usage of saline and a corresponding reduction in the overall size of the fluid collection reservoir. It is also believed that certain pathology analyses would benefit from not subjecting tissue samples to a saline flush. 
     In another aspect of the invention, a core biopsy device has a probe assembly with a probe support structure that holds a probe having a side aperture. A cutter tube is slidingly received by the probe and sized to translate across the side aperture to sever prolapsed tissue. A hand piece includes a hand piece support structure having a lateral engaging portion that receives the probe assembly. Thereby, an economical incorporation of a replaceable probe and cutter tube into a laterally mounted assembly allows reuse of a powered hand piece, yet also provides an advantageous saline flush capability of the probe assembly. 
     In yet another aspect of the invention, a hand piece of a biopsy device has a proximal carriage that is also translated by the lead screw. The proximal carriage selectively actuates, when the distal carriage is distally positioned, a flush valve assembly contained in a probe assembly. A needle of the probe assembly has a cutter lumen for a cutter tube as well as a lateral lumen, both communicating with a side aperture in a probe tube. The same hand piece may instead be engaged to another probe assembly that utilizes the second carriage to actuate a tissue sample retraction mechanism. 
     In yet a further aspect of the invention, a biopsy system includes a hand-held device that is connected to a static vacuum source and to a fluid supply. The hand-held device includes a housing that is gripped to position a core biopsy probe. Actuating user controls on the housing translates a motor driven cutter that translates within the core biopsy probe to sever tissue that is prolapsed into a sample opening. Vacuum assist valve assembly in the hand-held device responds to positioning of the motor driven cutter to communicate static vacuum pressure from the static vacuum source to prolapse the tissue. Advantageously, a user may select to couple a fluid supply to the core biopsy probe to dispel debris and coagulated blood. 
     These and other objects and advantages of the present invention shall be made apparent from the accompanying drawings and the description thereof. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       While the specification concludes with claims particularly pointing out and distinctly claiming the present invention, it is believed the same will be better understood by reference to the following description, taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is a left front isometric view from above of a biopsy device with a disposable probe assembly detached from a reusable hand piece; 
         FIG. 2  is a right aft isometric view from below of the biopsy device of  FIG. 1 ; 
         FIG. 3  is a right isometric view from below the disposable probe assembly of  FIG. 1  disassembled to depict components of a vacuum assistance valve assembly and a saline flush valve assembly; 
         FIG. 4  is a longitudinal, vertical cross sectional view through a probe of the disposable probe assembly of  FIG. 1 ; 
         FIG. 5  is a longitudinal, horizontal cross sectional view through a vacuum assist valve assembly in an initial state (i.e., communicating supply vacuum to the probe to prolapse tissue) of the disposable probe assembly of  FIG. 1 ; 
         FIG. 6  a longitudinal, horizontal cross sectional view through the vacuum assist valve assembly in a distally translated state (i.e., communicating increased pressure such as atmospheric pressure to the probe) of the disposable probe assembly of  FIG. 1 ; 
         FIG. 7  is a longitudinal, horizontal cross sectional view viewed from below through a saline flush valve assembly in an initial, retracted state (i.e., communication allowed between center port of the vacuum assist valve assembly and the probe) of the disposable probe assembly of  FIG. 1 ; 
         FIG. 8  is a longitudinal, horizontal cross sectional view viewed from below through the saline flush valve assembly in a distally translated state (i.e., communication allowed between a saline supply conduit and the probe) of the disposable probe assembly of  FIG. 1 ; 
         FIG. 9  is a left isometric view from above of the reusable hand piece of  FIG. 1  with the handle housing shown in phantom to expose the dual carriages distally translated; 
         FIG. 10  is a right isometric view from below of the reusable hand piece of  FIG. 9  with the handle housing shown in phantom; 
         FIG. 11  is a left isometric exploded view from below of the reusable hand piece of  FIG. 1 ; 
         FIG. 12  is a left isometric view from slightly below the reusable hand piece with the handle housing removed to expose the distally positioned dual carriages and a portion of the disposable probe assembly installed with a generally rectangular cover removed; 
         FIG. 13  is a bottom view taken along a horizontal cross section through the probe of an assembled biopsy device of  FIG. 1  with dual carriages both distally positioned; 
         FIG. 14  is a left isometric detail view of the dual carriages in opposite translations as initially positioned during engagement of the disposable probe assembly and during insertion into tissue; 
         FIG. 15  is a bottom view taken in horizontal cross section through a lead screw of the reusable hand piece of  FIG. 14 ; 
         FIG. 16  is a left isometric view of portions of the biopsy device of  FIG. 1  depicted to include the dual carriages in the initial position and sleeve union in phantom and also depicted with the probe and pneumatic components of the disposable probe assembly; 
         FIG. 17  is a left isometric view from below the portions of the biopsy device of  FIG. 16  after retraction of the distal carriage; 
         FIG. 18  is a bottom isometric view of the frame and dual carriage portion of the biopsy device of  FIG. 1  with a horizontal portion cutaway made through the pneumatic components of the engaged disposable probe assembly with valving positioned such that vacuum is communicated to the lateral lumen; 
         FIG. 19  is a bottom isometric view of the frame and dual carriage portion of the biopsy device of  FIG. 1  with a horizontal portion cutaway made through the pneumatic components of the disposable probe assembly with valving positioned such that atmospheric pressure is communicated to the lateral lumen; 
         FIG. 20  is a left side view of the probe assembly of the biopsy device of  FIG. 1  taken in longitudinal cross section exposing a cutter tube distally positioned after severing a tissue sample being retracted by vacuum assistance; 
         FIG. 21  is a left isometric view of portions of the biopsy device of  FIG. 1  depicted to include the dual carriages in a distal position for saline flush and sleeve union in phantom and also depicted with the probe and pneumatic components of the disposable probe assembly; and 
         FIG. 22  is a bottom isometric view of the frame and dual carriage portion of the biopsy device of  FIG. 1  with a horizontal portion cutaway made through the pneumatic components of the engaged disposable probe assembly with valving positioned such that saline is communicated to the lateral lumen. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In  FIGS. 1-2 , a biopsy device  10  has a reusable hand piece  12  and a disposable probe  14  that enables economical taking of multiple percutaneous core biopsy samples by accessing a standard medical vacuum pump or wall-mounted vacuum access port (not shown) through an interfacing vacuum conduit  16 . In addition, the biopsy device  10  advantageously incorporates a saline flush capability received from saline supply conduit  17 . In the illustrative version, the reusable hand piece  12  is self-powered and suitable for use in conjunction with ultrasonic diagnostic imaging. The disposable probe  14  reduces the portion of biopsy device  10  that requires protective packaging to avoid contact with sharp surfaces and to keep it sterile prior to use. Further economy is accomplished by reducing the portion of the biopsy device  10  that is disposed as medical waste between uses. Movable components of the disposable probe  14  are advantageously locked until mounted in an access trough  18  formed in a handle housing  20  of the reusable hand piece  12 . It should be appreciated that one or more standard mechanical, pneumatic, or electrical latches (not shown) may be integrated into the biopsy device  10  to secure the disposable probe  14  to the reusable hand piece  12 . 
     In  FIGS. 1-4 , the disposable probe assembly  14  includes a substantially rectangular cover  22  sized to close the access trough recess  18  ( FIGS. 1-2 ). An end slot  24  formed in the cover  20  ( FIGS. 1-2 ,  5 - 6 ) is closed by a probe union sleeve  26  attached to an inner surface  27  ( FIG. 1 ) of the substantially rectangular cover  22 . A core biopsy needle (“probe”) assembly  28  passes longitudinally through the probe union sleeve  26  and is formed by a probe tube  30  that includes an underlying lateral (vacuum) lumen  32  that communicates with a side aperture  34  ( FIG. 1 ) via holes  35  ( FIG. 4 ) near a distal opening  36  of the probe tube  30  that is closed by a piercing tip  38 . A cutter tube  40  is sized to closely fit and translate within an inner diameter (i.e., cutter lumen) of the probe tube  30  with a length sufficient to close the side aperture  34  with a proximal end  42  extending from the probe union sleeve  26  to attach to a cutter gear  44 , as depicted in  FIG. 1 . 
     It should be appreciated that the probe tube defines first and second fluid passages that are separated longitudinally within the probe tube and distally communicate with each other at the side aperture  34 . In the illustrative version, the first fluid passage is defined within the cutter tube  40  and the second fluid passage is defined within the lateral lumen  32  that is “hard walled” apart from a cylindrical portion of the cutter lumen of the probe tube  35 . However, for a cylindrical probe tube (not shown), a cutter tube may be axially offset within the cutter lumen of the probe tube such that the cutter tube may separate the first and second fluid passages, especially if the cutter tube need not be retracted for retraction of samples (e.g., vacuum retraction, straw retraction, single sample per insertion devices). 
     With particular reference to  FIG. 3 , sample retrieval tube  46  is received within a proximal opening in the cutter gear  44  and in turn proximally terminates itself at a half cylinder connector  47  positioned proximate to a rear support bracket  49  attached to the generally rectangular cover  22 . As described in the cross referenced application Ser. No. 11/198,558, the half cylinder connector  47  attaches to a moving portion of a sample holding apparatus and the rear support bracket  49  attaches to a stationary portion of the sample holding apparatus (proximal sample stacker  48 ). The relative movement increments a capture mechanism as samples are proximally stacked with vacuum being ported through the half cylinder connector  47  and sample retrieval tube  46  to extract samples from the cutter tube  40 . 
     With continued reference to  FIG. 3 , proximal to the probe union sleeve  26  is an elongate slot  50  that is part of a vacuum assist valve assembly  52 . The cutter gear  44  includes distal and proximal annular recesses  54 ,  56  flanking spur gear teeth  58  that engage the reusable hand piece  12  as described below. A more distal annular recess  60  is gripped by a first valve post  62  that is engaged to longitudinally translate in an elongate post slot  64  of a distal portion  66  of a vacuum valve actuator  68 . 
     In  FIGS. 3 ,  5 , a cylindrical proximal portion  70  of the vacuum valve actuator  68  has distal and proximal O-ring grooves  72 ,  73  that respectively retain distal and proximal dynamic O-ring seals  74 ,  75  that move within a distally open cylindrical valve bore  76  of a vacuum valve body  78  molded onto an outer surface  79  of the substantially rectangular cover  22 . 
     In an initial state depicted in  FIG. 5 , the vacuum valve actuator  68  is in a retracted position (along with the cutter tube  40 ), allowing communication between a proximal vacuum port  80  and a center vacuum port  82 . In  FIG. 6 , distal translation of the vacuum valve actuator  68  enables communication between the center vacuum port  82  and a distal vacuum port  84 . The center vacuum port  82  is attached to a proximal end of a distal vacuum conduit  86  whose other distal end is connected through the rectangular cover  22  to the probe union sleeve  26  ( FIGS. 2-3 ). It should be appreciated that the probe union sleeve  26  includes fluidic passages that communicate between the proximal end of the vacuum lumen  32  and the distal vacuum conduit  86  as allowed by the saline flush valve assembly  87  ( FIG. 7 ). 
     Returning to the vacuum assist valve assembly  52  of  FIGS. 2-3 ,  5 - 6 , the distal vacuum port  84  is attached to a hose nib  88  that is exposed to atmospheric pressure. Hose nib  88  may include an air and/or saline filter. Alternatively, hose nib  88  may be connected to a positive pressure source (e.g., fluid pump) or a negative pressure source (e.g., vacuum pump, syringe) to aspirate fluids. Likewise, hose nib  88  may be used to lavage the tissue cavity with saline, pain medication, or bleeding control fluids. The proximal vacuum port  80  communicates through a proximal vacuum conduit  90  to the interfacing vacuum conduit  16 . 
     In  FIGS. 2-3 ,  7 - 8 , the flush valve assembly  87  includes a proximally open saline valve bore  92  formed in a saline valve body  94  molded onto the outer surface  79  of the substantially rectangular cover  22  distal to a laterally offset longitudinal slot  96  ( FIG. 3 ) defined in a distal portion of the substantially rectangular cover  22 . 
     With particular reference to  FIGS. 3 ,  7 , a saline valve actuator  98  includes a distal cylindrical spool  100  that is sized to be slidingly received within the proximally open saline valve bore  92 . A distal O-ring groove  102  that receives a distal saline O-ring  104  and a mid-shaft O-ring groove  106  that receives a mid-shaft saline O-ring  108  are spaced on the distal cylindrical spool  100  to selectively allow communication between a proximal saline port  110 , which is attached to the distal end of the distal vacuum conduit  86 , and a center molded conduit  112  that communicates through the probe sleeve union  26  to the vacuum lumen  32  when the saline valve actuator  98  is proximally positioned, as depicted in  FIG. 7 . When the saline valve actuator  98  is distally positioned, as depicted in  FIG. 8 , the center molded conduit  112  communicates with a distal saline port  114  that is attached to a proximal end of the saline supply conduit  17 . A proximal end of the saline valve actuator  98  is attached to a saline slot link  116  that longitudinally slides within the laterally offset longitudinal slot  96  extending a proximal carriage engagement member  118  out of the inner surface  27  of the substantially rectangular cover  22 . 
     With reference to  FIGS. 1-2 ,  9 - 11 , the reusable hand piece  12 , as described in previously cross referenced U.S. patent application Ser. No. 11/198,558 includes four user controls aligned on a top surface  160  of the housing  20 , specifically from most distal to most proximal: a forward motor rotation key  162 , a reverse motor rotation key  164 , a saline flush key  166  and a slide button  168  for selecting insertion mode or sample taking mode. The keys  162 - 166  control a control circuit  170 , which may include integral power storage (e.g., batteries, fuel cell, etc.) for untethered use. With particular reference to  FIG. 11 , the forward motor rotation key  162  causes a DC motor  172  to rotate its motor output shaft  174  in a forward rotation. A slide spur gear  176  includes an internal keyed engagement with a longitudinal key groove  178  on the motor output shaft  174  that allows longitudinal positioning by the slide button  168 . In particular, fore and aft brackets  180 ,  182  of the slide button  168  engage distal and aft annular grooves  184 ,  186  that flank spur gear teeth  188  of the slide spur gear  176 . 
     When the slide button  168  is moved distally, the slide spur gear  176  engages a tissue penetration gear  190  that spins on a common shaft centerline  192  forward of a gearbox input gear  196 . Gearbox input gear  196  consists of a distal small gear  198  and a proximal large gear  200 . The tissue penetration gear  190  has spur gear teeth  206  that engage the slide spur gear  176 . A frame post  212  projects proximally from an aft wall  234  of a frame  204  with a strike pin  214  projecting upwardly from the frame post  212 . In  FIGS. 11-12 , a circular cam wheel  216  is attached to a distal side of the tissue penetration gear  190 . Rotating the tissue penetration gear  190  urges the strike pin  214 , and thus the frame  204 , proximally. In  FIGS. 11 ,  13 , left and right spring cavities  218 ,  220  (when viewed from above), formed longitudinally in distal corners of the frame  204 , respectively receive inwardly projecting left and right tabs  222 ,  224  ( FIG. 13 ) from the cover  20  and receive left and right compression springs  226 ,  228 . In particular, a distal end of each compression spring  226 ,  228  presses against a distal inner surface of the respective spring cavity  218 ,  220 . A proximal end of each compression spring  226 ,  288  is grounded against a respective tab  222 ,  224  of the cover  20 . Thus, the frame  204  is biased distally within the cover  20 . Movement of the frame  204  proximally compresses these compression springs  226 ,  228  that thereafter assert a restoring force. 
     When the slide button  168  is moved proximally, the slide spear gear  176  is moved into engagement with the gearbox input gear  196 , specifically the distal small gear  198 , which engages and turns a translation large input gear  230  whose shaft  232  passes through the aft wall  234  of the frame  204 . The proximal large gear  200  of the gearbox input gear  196  engages and turns a rotation small input gear  236  whose shaft  238  passes through the aft wall  234 . The frame  204  includes a carriage recess  240 , defined between a partition  242  and the aft wall  234 . The carriage recess  240  contains longitudinally aligned left side lead (translation) screw  244  and right-side rotation spur gear  246  that are attached for rotation respectively with the shafts  232 ,  238 . The partition  242  is positioned aft of the left and right tabs  222 ,  224  of the cover  20  and also defines in part the left and right spring cavities  218 ,  220 . 
     The rotation spur gear  246  engages the cutter gear  44  when the disposable probe  14  is inserted, imparting a rotation as the cutter tube  40  and cutter gear  44  translate longitudinally in response to the rotation of the lead (translation) screw  244 . This translation is caused by lead screw threads  248 . In particular, a distal carriage (cutter carriage)  250  is longitudinally moved on the lead screw threads  248 . Distal and proximal J-hook extensions  252 ,  254  project downwardly from the distal carriage  250  to engage the distal and proximal annular recesses  54 ,  56  of the cutter gear  44  ( FIG. 3 ). Distal of the distal carriage  250 , a biasing spring  256  urges against the distal carriage  250 , which assists in engagement of the lead screw threads  248  with the distal carriage  250 . 
     In  FIGS. 11 ,  14 - 15 , a sliding pin  260  has a proximal carriage sliding pin retainer  266  attached to a proximal carriage  258 . A shaft  264  of the sliding pin  260  also passes through a distal carriage sliding pin retainer  270  attached to the distal carriage  250 . Sliding pin  260  has a proximal end  262  and a distal end  268  to prevent the sliding pin  260  from disengaging from the carriage sliding pin retainers  266 ,  270 . A sliding pin spring  272  resides on the sliding pin  260  and is constrained at each end by carriage sliding pin retainers  266 ,  270 . 
     With the components of the reusable handpiece  12  now introduced, a sequence of use of the biopsy device  10  will be described. The disposable probe assembly  14  is installed into the reusable hand piece  12 . In so doing, the distal carriage  250  engages the cutter gear  44  to position (translate) the cutter tube  40 , initially in a distal position as depicted in  FIG. 12 . During installation, the proximal carriage  258  engages the proximal carriage engagement member  118  feature located on saline slot link  116  that engages the proximal portion of the saline valve actuator  98 . A proximally stacking sample retrieving device  48  is attached to the disposable probe assembly  14  to provide a pneumatic vacuum bias to the cutter tube  40  and to hold retracted tissue samples. 
     With the biopsy device  10  assembled, the reusable handpiece  12  is manipulated to insert the piercing tip  38  of the core biopsy needle (probe) assembly  28  into tissue. Penetration of dense tissue is assisted by moving the slide button  168  distally to a “tissue insertion mode” wherein the slide spur gear  176  engages the tissue penetration gear  190 . Depression of the forward motor rotation key  162  turns these gears  176 ,  190  causing the circular cam wheel  216  to turn against strike pin  214  that creates proximal longitudinal motion of frame  204  and the attached core biopsy needle (probe) assembly  28  of approximately 0.1 inch at a rotation rate of 7 cycles per second ( FIG. 12 ). Left and right compression springs  226 ,  228  provide the restoring distal longitudinal motion to frame  204  and probe assembly  28  as left and right compression springs  226 ,  228  are repeatedly compressed between the distal surface of the left and right spring cavities  218 ,  220  of the frame  204  and the left and right tabs  222 ,  224  of the housing  20 . The restoring distal longitudinal motion to frame  204  and core biopsy needle (probe) assembly  28  result in a corresponding distal motion of piecing tip  38  that assists in penetrating tissue. 
     With the probe assembly  28  positioned, the slide button  168  is moved proximally to move slide spur gear  176  into engagement with the gearbox input gear  196 . Depression of the reverse motor rotation key  164  causes the distal carriage  250  to retract ( FIG. 17 ). Thereby, the vacuum assist valve assembly  52  ( FIG. 5 ) communicates vacuum through saline flush valve assembly  87  ( FIG. 7 ) of the disposable probe assembly  14  ( FIG. 18 ) through the vacuum lumen  32  to a now open side aperture  34  in the probe tube  30  ( FIG. 4 ) to prolapse tissue. Vacuum is maintained by a lower pressure also communicating through the cutter tube  40  through the proximal sample stacker  48 . Depression of the forward motor rotation key  162  ( FIG. 1 ) distally translates the distal carriage  250  and thus the cutter tube  40  to sever a tissue sample ( FIG. 20 ) as well as shifting the vacuum assist valve assembly  52  to a distal position ( FIG. 6 ) that communicates an increased pressure (e.g., atmosphere) through the saline flush valve assembly  87  ( FIG. 7 ) through the vacuum lumen  32  to the side aperture  34 , allowing the vacuum through the cutter tube  40  to retract the tissue sample ( FIG. 20 ). 
     At this point or after subsequent sample taking cycles, the surgeon my elect to flush tissue debris or coagulated blood from the vacuum lumen  32 , side aperture  34  and cutter tube  40  of the probe assembly  28 . By further depression of the forward motor rotation key  162 , the distal carriage  250  advances slightly forward, drawing the proximal carriage  258  onto the lead screw threads  248 , and thereafter the distal carriage  250  free wheels. Thereby, the flush valve assembly  87  switches from pneumatically coupling the lateral lumen  32  to the vacuum assist valve assembly  52  to coupling the saline supply (not shown) to the vacuum lumen  32 . Thereby, the vacuum drawn through the cutter tube  40  causes saline (or other liquid provided) to be drawn through the vacuum lumen  32  and into a distal end of the cutter tube  40  and out of the disposable probe assembly  14 , through proximal sample stacker  48  and then into the fluid collection canister (not shown) located near the vacuum pump. When the proximal carriage  250  is not fully distal, the flush valve  87  is positioned proximal of its fully distal position and prevents saline from communicating with the lateral lumen  32  of the probe assembly  28 . 
     Control implementation may include sensing of the position of the distal carriage  250  such that motor operation stops distal travel of the distal carriage  250  prior to distal translation of the proximal carriage  258 , requiring release of the forward motor rotation key  162  prior to actuating again to indicate a desire for saline flush. Alternatively, a separate override button (not shown) may be used that continues forward rotation of the lead screw  244  to effect the saline flush feature. 
     It should be appreciated that in the illustrative version, the distal carriage  250  does not freewheel in its proximal-most position. Instead, rotation of the motor is stopped as the distal carriage  250  is about to contact the proximal carriage  258  with closed-loop control based on an encoder (not shown) coupled to the DC motor  172  enabling accurate positioning of the motor output shaft  174 . Alternatively, freewheeling may be incorporated at the proximal-most position of the distal carriage  250  by adding a section of no helical threads to the proximal end of the lead (translation) screw  244  equal to the longitudinal thickness of the distal carriage  250 . 
     By virtue of the foregoing, with one-handed operation, a clinician is able to select between a plurality of ports (e.g., vacuum pressure, atmospheric pressure, saline supply) that can communicate with a side aperture  34  of a needle assembly  28  of core biopsy device  10 . In particular, valve mechanisms are contained on the hand piece that need only selectively port a constant vacuum source without the necessity for a separate, expensive programmed control module. One advantage of such an economical capability is providing “on-demand” saline flush to the side aperture  34  (or distal opening) of the needle assembly  28 . During normal tissue sampling, the side aperture  34  pressure levels transitions from vacuum during cutting to atmospheric pressure while the tissue sample is being transported proximally out of the reusable handpiece  12 . Clearing tissue debris from the needle assembly  28  at the press of a saline push key  166  during the sample ensures proper operation so that the desired number of samples may be taken. 
     It should be appreciated that any patent, publication, or other disclosure material, in whole or in part, that is said to be incorporated by reference herein is incorporated herein only to the extent that the incorporated material does not conflict with existing definitions, statements, or other disclosure material set forth in this disclosure. As such, and to the extent necessary, the disclosure as explicitly set forth herein supersedes any conflicting material incorporated herein by reference. Any material, or portion thereof, that is said to be incorporated by reference herein, but which conflicts with existing definitions, statements, or other disclosure material set forth herein, will only be incorporated to the extent that no conflict arises between that incorporated material and the existing disclosure material. 
     While preferred embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the spirit and scope of the appended claims. Additionally, each element described in relation to the invention may be alternatively described as a means for performing that element&#39;s function. 
     For example, one or more sensors may be incorporated into the hand piece  12  to sense the actual position of each carriage or to sense the particular disposable probe assembly assembled into the hand piece  12 . 
     As another example, use of a proximal carriage for saline flush takes advantage of this additional motive device that is dedicated for sample retrieval in other versions of the disposable probe assembly (i.e., straw). In some applications consistent with the present invention where two carriages are not required or desired, an alternative saline valve selection may be incorporated where a separate electromechanical valve actuator may be incorporated that is not driven by the lead screw. 
     As an additional example, biasing the cutter tube  40  with a vacuum source advantageously assists in both prolapsing tissue as well as retracting tissue samples from the probe assembly  28 . However, applications consistent with the present invention may include reversing the direction of fluid flow through the cutter tube and out of the lateral lumen  32 . In addition, prolapsing of tissue may be alternatively achieved by closing the lateral lumen and allowing the vacuum bias through the cutter tube  40  to effect tissue prolapse. In addition, a pressurized liquid source may be directed by the flush valve assembly to forcibly push out a tissue sample or debris without the assistance of a vacuum bias on the cutter tube. 
     As yet a further example, while the illustrative versions advantageously utilize a single motor and a single lead screw to translate two carriages, applications consistent with aspects of the present invention may use two motors and two lead screws or one motor selectively coupled to one of two lead screws, each having a carriage. 
     As yet an additional example, while selective depression of the saline push key  166  provides clinical flexibility, it should be appreciated that the dual carriage lends itself to alternatively mechanizing automatic saline flush after each cutting cycle.