Abstract:
A magnetic resonance imaging (MRI) compatible core biopsy system uses a biopsy device having intuitive graphical displays and a detachable remote keypad that advantageously allows convenient control even within the close confines afforded by a localization fixture installed within a breast coil that localizes a patient&#39;s breast and guides a probe of the biopsy device relative to the localized breast. A control module for interactive control and power generation are remotely positioned and communicate and transmit rotational mechanical energy via sheathed cable.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     The present application is a continuation in part of U.S. patent application Ser. No. 11/103,959, “MRI BIOPSY DEVICE LOCALIZATION FIXTURE” to Hughes et al., filed on 12 Apr. 2005, the disclosure of which is hereby incorporated by reference in its entirety. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates, in general, to a method of imaging assisted tissue sampling and, more particularly, to an improved method for positioning a biopsy probe with respect to a magnetic resonance imaging (MRI) breast coil for acquiring subcutaneous biopsies and for removing lesions.  
       BACKGROUND OF THE INVENTION  
       [0003]     Core biopsy devices have been combined with imaging technology to better target a lesion in breast tissue. One such commercially available product is marketed under the trademark name MAMMOTOME™, by Ethicon Endo-Surgery, Inc. An embodiment of such a device is described in U.S. Pat. No. 5,526,822 issued to Burbank, et al., on Jun. 18, 1996, and is hereby incorporated herein by reference. Its handle receives mechanical and electrical power as well as vacuum assist from a remotely positioned control module that is spaced away from the high magnetic field of a Magnetic Resonance Imaging (MRI) machine.  
         [0004]     As seen from that reference, the instrument is a type of image-guided, percutaneous coring, breast biopsy instrument. It is vacuum-assisted, and some of the steps for retrieving the tissue samples have been automated. The physician uses this device to capture “actively” (using the vacuum) the tissue prior to severing it from the body. This allows the sampling of tissues of varying hardness. In addition, a side opening aperture is used, avoiding having to thrust into a lesion, which may tend to push the mass away, cause a track metastasis, or cause a hematoma that, with residual contrast agent circulating therein, may mimic enhancement in a suspicious lesion. The side aperture may be rotated about a longitudinal axis of the probe, thereby allowing multiple tissue samples without having to otherwise reposition the probe. These features allow for substantial sampling of large lesions and complete removal of small ones.  
         [0005]     Vacuum assisted core biopsy devices have been adapted to be safe and compatible with various imaging modalities, including Magnetic Resonance Imaging (MRI). In particular, portions of a biopsy system placed near the magnet core of an MRI machine need to be nonresponsive to the strong magnetic field to prevent becoming drawn toward the magnet core or to malfunction. Further, the MRI machine depends upon sensing extremely weak radio frequency (RF) signals emanated by tissue after being excited by a strong change in the magnetic field. Components placed in the RF shielded MRI suite need to avoid producing electromagnetic interference (EMI) and need to avoid having materials that would distort RF signals sufficient to create artifacts in the MRI scan data.  
         [0006]     A successful approach has been to segregate motive power generation, graphical user interface, vacuum assist, and closed loop control in a control module that has typically been placed about 6 feet away from the magnet core to mitigate detrimental interaction with its strong magnetic field and/or sensitive radio frequency (RF) signal detection antennas. An intuitive graphical user interface (GUI) provides a range of preprogrammed functionality incorporated into a control module to efficiently use time in an MRI suite to take tissue samples.  
         [0007]     As an example, in U.S. Pat. No. 6,752,768, the disclosure of which is hereby incorporated by reference in its entirety, a control button may be depressed to change a mode of operation of a core biopsy device with this mode displayed remotely on a display.  
         [0008]     While a full function GUI has numerous clinical benefits, the clinician may find the control module inconveniently remote during hands-on portions of the procedure. In addition, some MRI machines have such increased sensitivity and/or increased magnet field strength that it is desirable to increase the distance of the control monitor (e.g., 30 feet) from the MRI machine. Further, even if the control monitor is sufficiently close, some clinicians prefer a simplified user interface to simplify training familiarity.  
         [0009]     Consequently, a significant need exists for a biopsy system compatible for use in an MRI suite with biopsy controls with enhanced convenience and intuitiveness.  
       BRIEF SUMMARY OF THE INVENTION  
       [0010]     The invention overcomes the above-noted and other deficiencies of the prior art by providing a handpiece of a magnetic resonance imaging (MRI) compatible core biopsy system that includes a graphical user interface that facilitates user control even with vacuum, power generation, and control processing components remotely positioned away from the MRI magnet and sensitive radio frequency (RF) receiving components. Thereby, a clinician may have the full functionality of vacuum assisted core biopsy systems yet not be inconvenienced by the distance from a remotely positioned control module.  
         [0011]     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 FIGURES  
       [0012]     The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention, and, together with the general description of the invention given above, and the detailed description of the embodiments given below, serve to explain the principles of the present invention.  
         [0013]      FIG. 1  is a perspective disassembled view of a Magnetic Resonance Imaging (MRI) biopsy system including a handpiece (“biopsy device”) having intuitive graphical controls consistent with aspects of the invention.  
         [0014]      FIG. 2  is an isometric view of a lateral fence and pedestal of a localization fixture of the MRI biopsy system of  FIG. 1 .  
         [0015]      FIG. 3  is an isometric view of a guidance assembly mounted on a right primary targeting rail of  FIG. 2 .  
         [0016]      FIG. 4  is an exploded isometric view of the guidance assembly of  FIG. 3  and the sleeve trocar and introducer obturator of  FIG. 1 .  
         [0017]      FIG. 5  is an isometric view of the introducer obturator inserted into the sleeve trocar of  FIGS. 1 and 4 .  
         [0018]      FIG. 6  is an aft right isometric view of the MRI biopsy device of  FIG. 1  with a disposable probe assembly and keypad control disengaged from a reusable holster portion.  
         [0019]      FIG. 7  is a fore left isometric view of the MRI biopsy device of  FIG. 1  with the disposable probe assembly and keypad control disengaged from the reusable holster portion.  
         [0020]      FIG. 8  is a fore left exploded isometric view of the reusable holster portion of  FIG. 7 .  
         [0021]      FIG. 9  is a top view of the disposable probe assembly of  FIG. 7  with an upper cover removed to expose interior components of a carriage cavity.  
         [0022]      FIG. 10  is a fore left exploded isometric view of the disposable probe assembly of  FIG. 7 .  
         [0023]      FIG. 11  is an aft left isometric view of the localization fixture and guidance assembly installed into a breast coil of  FIG. 1 .  
         [0024]      FIG. 12  is an aft isometric view of the MRI biopsy device of  FIG. 7  into the guidance assembly of  FIG. 11 .  
         [0025]      FIG. 13  is a top detail view of a display portion of the MRI biopsy device of  FIG. 7 .  
         [0026]      FIG. 14  is an aft right isometric view of the MRI biopsy device, localization fixture and breast coil of  FIG. 12  with insertion of a marker deploying instrument through a probe of the disposable probe assembly. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0027]     An MRI biopsy device advantageously includes is partially disposable for sterility purposes with a reusable portion for economy. Inconvenience of mechanical, electrical, and pneumatical coupling to a remotely placed control portion, necessitated by a strong magnetic field and sensitive RF receiving components of an MRI machine, is mitigated. First, proximal detachable intuitive controls and displays on the MRI biopsy device give interactive control even after insertion into localizing and guiding structures. Second, binding of mechanical coupling to the MRI biopsy device is sensed prior to equipment damage or malfunction. Third, mechanical coupling is moved closer to engagement points between the MRI biopsy device and guiding structures to reduce torque loads, especially those transferred through its distal probe. Fourth, a single mechanical drive cable drives a fixed ratio transmission that translates and rotates a cutter of the distal probe to realize an effective fixed ratio translation/rotation sampling cut without the encumbrance of two mechanical drive cables.  
         [0028]     Turning to the Drawings, wherein like numerals denote like components throughout the several views, in  FIGS. 1-3 , a Magnetic Resonance Imaging (MRI) compatible biopsy system  10  has a control module  12  that typically is placed outside of a shielded room containing an MRI machine (not shown) or at least spaced away to mitigate detrimental interaction with its strong magnetic field and/or sensitive radio frequency (RF) signal detection antennas. As described in U.S. Pat. No. 6,752,768, which is hereby incorporated by reference in its entirety, a range of preprogrammed functionality is incorporated into the control module  12  to assist in taking these tissue samples. The control module  12  controls and powers an MRI biopsy device (“handpiece”)  14  that is positioned and guided by a localization fixture  16  attached to a breast coil  18  that is placed upon a gantry (not shown) of the MRI machine.  
         [0029]     A cable management spool  20  is placed upon a cable management attachment saddle  22  that projects from a side of the control module  12 . Wound upon the cable management spool  20  is a paired electrical cable  24  and mechanical cable  26  which are bundled into sheathed cable  27  for communicating control signals and cutter rotation/advancement motions respectively. In particular, electrical and mechanical cables  24 ,  26  each have one end connected to respective electrical and mechanical ports  28 ,  30  in the control module  12  and another end connected to a reusable holster portion  32  of the MRI biopsy device  14 . An MRI docking cup  34 , which may hold the holster portion  32  when not in use, is hooked to the control module  12  by a docking station mounting bracket  36 .  
         [0030]     An interface lock box  38  mounted to a wall provides a tether  40  to a lockout port  42  on the control module  12 . The tether  40  is advantageously uniquely terminated and of short length to preclude inadvertent positioning of the control module  12  too close to the MRI machine. An in-line enclosure  44  may advantageously register the tether  40 , electrical cable  24  and mechanical cable  26  to their respective ports  42 ,  28 ,  30  on the control module  12 .  
         [0031]     Vacuum assist is provided by a first vacuum line  46  that connects between the control module  12  and an outlet port  48  of a vacuum canister  50  that catches liquid and solid debris. A tubing kit  52  completes the pneumatic communication between the control module  12  and the MRI biopsy device  14 . In particular, a second vacuum line  54  is connected to an inlet port  56  of the vacuum canister  50 . The second vacuum line  54  divides into two vacuum lines  58 ,  60  that are attached to the MRI biopsy device  14 . With the MRI biopsy device  14  installed in the holster portion  32 , the control module  12  performs a functional check. Saline is manually injected into biopsy device  14  to serve as a lubricant and to assist in achieving a vacuum seal. The control module  12  actuates a cutter mechanism (not shown) in the MRI biopsy device  14 , monitoring full travel. Binding in the mechanical cable  26  or within the biopsy device  14  is monitored with reference to motor force exerted to turn the mechanical cable  26  and/or an amount of twist in the mechanical cable  26  sensed in comparing rotary speed or position at each end of the mechanical cable  26 .  
         [0032]     Just proximal to a display area  61  on the reusable holster portion  32 , a remote keypad  62 , which is detachable from the reusable holster portion  32 , communicates via the electrical cable  24  to the control module  12  to enhance clinician control of the MRI biopsy device  14 , especially when controls that would otherwise be on the MRI biopsy device  14  itself are not readily accessible after insertion into the localization fixture  16  and/or placement of the control module  12  is inconveniently remote (e.g., 30 feet away). An aft end thumbwheel  63  on the reusable holster portion  32  is also readily accessible after insertion to rotate the side from which a tissue sample is to be taken.  
         [0033]     Left and right parallel upper guides  64 ,  66  of a localization framework  68  are laterally adjustably received respectively within left and right parallel upper tracks  70 ,  72  attached to an under side  74  and to each side of a selected breast aperture  76  formed in a patient support platform  78  of the breast coil  18 . A base  80  of the breast coil  18  is connected by centerline pillars  82  that are attached to the patient support platform  78  between the breast apertures  76 . Also, a pair of outer vertical support pillars  84 ,  86  on each side spaced about a respective breast aperture  76  respectively define a lateral recess  88  within which the localization fixture  16  resides.  
         [0034]     In  FIGS. 1-2 , a selected breast is compressed along an inner (medial) side by a medial plate  90  downwardly received into a medial three-sided frame  92  of the localization framework  68 . The breast is compressed from an outside (lateral) side of the breast by a lateral fence  94  downwardly received into a lateral three-sided frame  96  of the localization framework  68 , defining an X-Y plane. The X-axis is vertical (sagittal) with respect to a standing patient and corresponds to a left to right axis as viewed by a clinician facing the externally exposed portion of the localization fixture  16 .  
         [0035]     Perpendicular to this X-Y plane extending toward the medial side of the breast is the Z-axis, which typically corresponds to the orientation and depth of insertion of a probe  98  of a disposable probe assembly  100  of the MRI biopsy device  14  or of a sleeve trocar  102  with inserted introducer obturator  104 . For clarity, the term Z-axis may be used interchangeably with “axis of penetration”, although the latter may or may not be orthogonal to the spatial coordinates used to locate an insertion point on the patient. Versions of the localization fixture  16  described herein allow a nonorthogonal axis of penetration to the X-Y axis to a lesion at a convenient or clinically beneficial angle. An origin of the spatial coordinates may be imaging the dents imparted to the tissue by the lateral fence  94 . Alternatively, a disposable fiducial pointer  106  held by a fiducial holder  108  is filled with an MRI imagable material (e.g., KY jelly, saline, gadolinium) and sealed with a cap  110 .  
         [0036]     The probe  98 , sleeve trocar  102  and fiducial pointer  106  are guided by the localization fixture  16 . With particular reference to  FIG. 2 , a lateral fence supported pedestal  120  spatially positions left and right primary targeting rails  121 ,  122  that in turn guide the fiducial pointer  106 , the sleeve/trocar  102 , or the probe  98  of the biopsy device  14  ( FIG. 1 ). The primary targeting rails  121 ,  122  each include an attachment axle  124  that receives in either a left or right side axle hub  125  of a (Y-axis) height yoke  126  that is vertically adjustable upon a pedestal main body  128 , that in turn is laterally adjustable upon the lateral fence  94 . Alternatively, a breast coil may enable mounting the pedestal main body on the medial plate  90  for accessing medially. The pedestal main body  128  includes a proximal upright rectangular column  132  with a thinner wall  134  projecting from its distal side that flares laterally outward (defining left and right vertical rectangular slots  136 ,  138 ) as part of a bracket  140  with top and bottom hanger arms  144 ,  146  that slide laterally respectively on a top track  148  and a proximally open lower track  150  formed in the lateral fence  94 . A lateral (X-axis) adjustment lever  151  may be raised to lift its distal end  149  out of engagement with a bottom track  147  formed in the lateral fence  94  as the lateral adjustment lever  151  is repositioned to the left or right to a desired location with reference to a lateral measurement guide  145 .  
         [0037]     The height yoke  126  is a rectangular cuff interrupted in a mid-portion of a distal side to form locking left and right hands  152  respectively which ride vertically in the left and right vertical rectangular slots  136 ,  138 . The locking left and right hands  152  have respective ridged proximal surfaces (not shown) that are selectively drawn proximally into locking engagement by a height locking lever  156  with a ridged surface  158  on a proximal side of each vertical rectangular slot  136 ,  138 . Lifting the height locking lever  156  takes the height yoke  126  out of locking engagement to the pedestal main body  128  as the height yoke  126  is vertically repositioned. For height adjustment, the proximal top surface of the height yoke  126  serves as a sight  160  to read a height measurement scale  162  presented on a proximal surface of the height locking lever  156 .  
         [0038]     The attachment axle  124  allows rotation so that an axis of penetration may include an upward or downward trajectory. In the illustrative version, proximal corners of the height yoke  126  include angle detents  164  (e.g., −15°, 0°, +15°) that are selectable by an angle lock lever  166 . The primary targeting rail  122  includes a distal detent  167  that serves as a home reference for the fiducial holder  108  ( FIG. 1 ).  
         [0039]     In  FIGS. 3-4 , a guidance assembly  200 , that may be attached to the lateral fence supported pedestal  120  of  FIG. 2 , includes a cradle  202  whose upper lateral side  202   a  flares upwardly to engage a bottom channel  203  of the primary targeting rail  122 . A lower lateral side  202   b  flares horizontally to provide a holster guide track  204  that underlies the axis of penetration. To provide additional guidance to the MRI biopsy device  14  ( FIG. 1 ), a secondary targeting rail  206  includes a lateral channel  208  that is guided along a longitudinal guide tab  210  of the primary targeting rail  122 . When fully engaged thereon, a pawl  212  pivoting under urging of a pawl spring  214  about a vertical pawl pin  216  in a lateral window  218  proximally positioned in the secondary targeting rail  206  drops into a proximal detent  220  proximally positioned on the primary targeting rail  122 . The pawl spring  214  may maintain the pawl  212  in a neutral position that serves in both assembly and later removal of the secondary targeting rail  206  or comprises a pair of opposing pawl springs (not shown) for that purpose.  
         [0040]     In  FIGS. 4-5 , the sleeve trocar  102  includes a hollow shaft (or cannula)  223  that is proximally attached to a cylindrical hub  224  and has a lateral aperture  226  proximate to an open distal end  228 . The cylindrical hub  224  has an exteriorly presented thumbwheel  230  for rotating the lateral aperture  226 . The cylindrical hub  224  has an interior recess  232  that encompasses a duckbill seal  234 , wiper seal  236  and a seal retainer  238  to provide a fluid seal when the shaft  223  is empty and for sealing to the inserted introducer obturator  104 .  
         [0041]     The introducer obturator  104  advantageously incorporates a number of components with corresponding features. A hollow shaft  242  includes a fluid lumen  244  that communicates between an imageable side notch  246  and a proximal port  248 . The hollow shaft  242  is longitudinally sized to extend when fully engaging a piercing tip  249  out of the distal end  228  of the sleeve trocar  102 . An obturator handle  250  encompasses the proximal port  248  and includes a locking feature  252 , which includes a visible angle indicator  254 , that engages the sleeve thumbwheel  230  to ensure that the imageable side notch  246  is registered to the lateral aperture  226  in the sleeve trocar  102 . An obturator seal cap  256  may be engaged proximally into the obturator handle  250  to close the fluid lumen  244 . The obturator seal cap  256  includes a locking or locating feature  258  that includes a visible angle indicator  259  that corresponds with the visible angle indicator  254  on the obturator thumbwheel cap  230 . The obturator seal cap  256  may be fashioned from either a rigid, soft, or elastomeric material.  
         [0042]     Returning to  FIGS. 3, 4 , the sleeve trocar  102  is guided, during penetration of tissue, by a sleeve mount  260  having a sleeve hub  262  that receives the cylindrical hub  224  of the sleeve trocar  102 . The sleeve mount  260  has a lateral sleeve hub channel  264  that slides along top and bottom guide flanges  266 ,  268  of the secondary targeting rail  206 , each having an aligned and recess ridged, ratcheting surface  270  that interacts with a respective top and bottom ratcheting feature  272 ,  274  on respective top and bottom rail lock rocker latches  276 ,  278  that are engaged by respective top and bottom latch pins  280 ,  282  in respective sides of the sleeve mount  260 . The ratcheting features  272 ,  274  are proximally ramped such as to allow distal movement. Distal portions of each rail lock rocker latches  276 ,  278  are biased away from the sleeve mount  260  by respective rail lock compression springs  284 ,  286  to bias the ratcheting features  272 ,  274  into contact with the ridges surfaces  270  of the guide flanges  266 ,  268 . Simultaneous depression of the rail lock rocker latches  276 ,  278  allow the sleeve mount  260  to be drawn proximally, withdrawing any sleeve trocar  102  supported therein, until the sleeve mount  260  reaches a proximal end of the secondary targeting rail  206 , whereupon the sleeve mount  260  rotates the pawl  212  clockwise (as viewed from the top) and is thus engaged to the secondary targeting rail  206  as the secondary targeting rail  206  is unlocked from the primary targeting rail  122 , causing removal therefrom with continued proximal movement.  
         [0043]     Before mounting the secondary targeting rail  206  onto the primary targeting rail  122  in the first place, the sleeve mount  260  is advantageously adjustably positioned on the secondary targeting rail  206  to set a desired depth of penetration. In particular, a depth guide  290  is formed by a crescent-shaped depth indicator  292  having a lateral channel  296  shaped to engage the top and bottom guide flanges  266 ,  268 . Forward ramped surfaces  298  on the top and bottom of the lateral channel  296  are positioned to engage the ridged ratcheting surfaces  270  on the secondary targeting rail  206 , allowing assembly by inserting the depth indicator  292  from a distal end of the secondary targeting rail  206 . Frictional engagement thereafter resists further proximal movement and strongly opposes any distal movement, especially from a depth lead screw  300  of the depth guide  290 , whose distal end  302  rotates within an outboard hole  304  in the depth indicator  292  and whose proximal end deflects laterally as a depth actuator lever  305  is used to rotate and longitudinally position the depth lead screw  300  therein. A mid portion of the depth lead screw  300  is received in a longitudinal through hole  306  formed in the sleeve mount  260  outboard of its lateral channel  208 . For coarse depth adjustment, outer lead threads  307  on the depth lead screw  300  selectively engage the sleeve mount  260  until top and bottom coarse adjust buttons  308 ,  310  are inwardly depressed into the sleeve mount  260 , compressing respective top and bottom coarse adjust compression springs  312 ,  314 . Each coarse adjust button  308 ,  310  includes a respective vertically elongate aperture  316 ,  318  whose inward surface presents a worm gear segment  320 ,  322  to engage the outer lead threads  307  on the depth lead screw  300  when urged into engagement by relaxed coarse adjust compression screws  312 ,  314 .  
         [0044]     Returning to  FIG. 3 , the thumbwheel  230  is depicted as engaged to the sleeve hug  262  of the sleeve mount  260  with other portions of the sleeve trocar  102  omitted. Applications consistent with the present invention may include a probe of an MRI biopsy device that includes a piercing tip or that otherwise is used without passing through a hollow shaft (cannula)  223 . As such, the thumbwheel with similar sealing members may be incorporated into the sleeve mount  260 .  
         [0045]     In  FIGS. 6-7 , the MRI biopsy device  14  has the disposable probe assembly  100  depicted detached from the reusable holster portion  32  and with the remote keypad  62  released from the reusable holster portion  32 . The sheathed cable  27  is joined to an underside of the reusable holster portion  32  distal to the aft end thumbwheel  63  to enhance balance and support of the reusable holster portion, which in turn may be engaged to the holster guide track  204  ( FIG. 4 ) by an I-beam shaped holster rail  324  whose upper surface  326  is engaged within a bottom channel  328  of a holster base plate  330 . A ridged member  331  upon the holster base plate  330  guides the disposable probe assembly  100  during engagement. A narrowed upper distal surface  332  of the holster rail  324  also engages downward gripping flanges  334  extending downward just proximal to a distal thumbwheel  336  of the disposable probe assembly  100 . An under slung shell  337  is fastened to the proximal undersurface portion of the holster base plate  330 .  
         [0046]     The disposable probe assembly  100  also has an undersurface that backwardly slides into engagement with the reusable holster portion  32 . In particular, a narrowed proximal end  338  is formed into an upper cover  340  with a distal locking arm  342  separated from the upper cover  340  on each side except proximally to present an unlocking button  344  on an exposed surface  346  of the upper cover  340  that is depressed to disengage a locking surface  348  ( FIG. 6 ) from a distal lip  350  of a distally open receiving aperture  352  in the reusable holster portion  32  of the holster plate  330 .  
         [0047]     A recessed deck  354  in an upper proximal surface of a proximal top cover  356  of the reusable holster portion  32  is shaped to receive the remote keypad  62 . A lower shell  358  mates to the proximal top cover  356 . The proximal top cover  356  also defines the upper portion of the receiving aperture  352 . The recessed deck  354  has a front guide hole  360  and a back locking aperture  362  registered to respectively receive a front tooth  363  and a flexing unlock tab  364  at an aft end of the remote keypad  62  to selectively engage and disengage the keypad  62  from the reusable holster portion  32 . The keypad  62  also includes a translation rocker button  366  that has a distal advance, a default neutral, and an aft retract command position. An aft button  368  may be programmed for mode functions such as saline flush.  
         [0048]     With particular reference to  FIG. 6 , the disposable probe assembly  100  has a plurality of interconnections presented on an aft docking end  370 . A rightward canted vacuum hose nib  372  is positioned to receive a vacuum conduit (not shown) that would be gripped by a friction clip  373  extending under and aft thereof to prevent inadvertent release. A right side slot  374  is distally open and formed between the holster base plate  330  and proximal top cover  356  to receive such a vacuum conduit as the disposable probe assembly  100  is engaged to the reusable holster portion  32 . A center splined driveshaft  375  engages the aft end thumbwheel  63  and communicates with the distal thumbwheel  336  to rotate a side aperture  376  in probe  98  to a desired side, as visually confirmed by an arrow indicator  378  on the distal thumbwheel  336 . A right splined driveshaft  380  effects cutter translation and a left splined driveshaft  382  effects cutter rotation.  
         [0049]     The distal thumbwheel  336  and probe  98  are mounted to a cylindrical hub  384 , which is a distal portion of the lower shell  358  that extends beyond the mating with the upper cover  340 . A sample through hole  386  communicates through the cylindrical hub  384  for receiving a rotating and translating cutter tube  388  ( FIG. 9 ) that enters the probe  98  and for receiving tissue samples (not shown) deposited by a retracting cutter tube  388 . As the cutter tube  388  fully retracts into a carriage cavity  390  formed between the upper cover  340  and proximal portion of the lower shell  358 , a distally extending tip  392  from a vacuum tube  394  encompassed by the cutter tube  388  dislodges the retracted tissue sample onto a sample retrieval platform  396 , which is a relieved area between the upper cover  340  and the cylindrical hub  384 .  
         [0050]     In  FIG. 8 , it should be appreciated that the sheathed cable  27  connects to the holster base plate  330  and communicates a single mechanical drive rotation to a fixed ratio transmission  398  mounted to the holster base plate  330  and electrically communicates with an encoder  400  coupled to the fixed ratio transmission  398  aft of the receiving aperture  352 . The sheathed cable  27  also communicates electrically with the display area  61  via a wire bundle (not shown) and with the keypad  62  via a cable assembly  402 , the latter including a strain relief bracket  404  that grips a keypad cable  406  and is fastened proximate to the sheathed cable  27 . The fixed ratio transmission  398  has a pass-through port  408  that receives a distal end the center splined driveshaft  375  ( FIG. 6 ) to rotatingly engage a proximally received beveled shaft  410  distally presented by the aft end thumbwheel  63  and sealed by an O-ring  412 . A right port  414  distally presented by the fixed ratio transmission  398  engages for rotation the right splined driveshaft  380  from the disposable probe assembly  100  for advancing and retracting (“translation”) the cutter tube  388 . A left port  416  distally presented by the fixed ratio transmission  398  engages for rotation the left splined driveshaft  382  from the disposable probe assembly  100  for rotating the cutter tube  388  when a distal cutting edge of the cutter tube  388  slides past the side aperture  376  of the probe  98 .  
         [0051]     In  FIGS. 9-10 , the carriage cavity  390  of the disposable probe assembly  100  includes a cutter carriage  418  having a threaded longitudinal bore  420  that encompasses an elongate translation shaft  422  whose proximal termination is the right splined driveshaft  380  supported by an aft right cylindrical bearing  424  received in an aft wall  425  of the lower shell  358 . A race about the outer circumference of the cylindrical bearing  424  receives an O-ring  426 . A distal end  428  of the threaded translation shaft  422  rotates within a distal right cylindrical bearing  430  engaged to a forward wall  432  of the lower shell  358 . A race about the outer circumference of the cylindrical bearing  430  receives an O-ring  434 . A threaded central portion  436  of the elongate translation shaft  422  resides between an unthreaded distal over-run portion  438  and an unthreaded proximal over-run portion  440 , both sized to allow the threaded longitudinal bore  420  of the cutter carriage  418  to disengage from the threaded central portion  436 .  
         [0052]     A distal compression spring  442  and a proximal compression spring  444  respectively reside on the unthreaded distal and proximal over-run portions  438 ,  440  to urge the threaded longitudinal bore  420  of the cutter carriage  418  back into engagement with the threaded central portion  436  upon reversal of rotation of the elongate translation shaft  422 . In particular, the cutter carriage  418  includes a top longitudinal channel  446  that slidingly engages an undersurface of the upper cover  340  (not shown) and a bottom longitudinal guide  448  that engages a longitudinal track  450  on a top surface of the lower shell  358 . Thus rotationally constrained, rotation of the elongate translation shaft  422  causes corresponding longitudinal translation of the cutter carriage  418  with distal and aft pairs of gripping flanges  452 ,  454  maintained laterally to the left to engage respectively distal and proximal races  456 ,  458  formed on each side of a toothed portion  460  of a cutter spur gear  462 , which has a longitudinal bore for applying vacuum.  
         [0053]     To that end, the vacuum hose nib  372  is attached to a mounting structure  464  that is gripped between the upper cover  340  and the lower shell  358  to present an orifice  466  within the carriage cavity  390  that is aligned with the longitudinal bore of the cutter gear  462  and that is in fluid communication with the vacuum hose nib  372 .  
         [0054]     With particular reference to  FIG. 10 , the proximal end of the vacuum tube  394  is received in the orifice  466 . A rectangular guide  467  supports the distally extending tip  392  of the vacuum tube  394  and is engaged between the upper cover  340  and the lower shell  358 . The cutter tube  388  encompasses and translates relative to the vacuum tube  394 . A seal cap  468  attached to a proximal end of the cutter gear  462  dynamically seals to the outer circumference of the vacuum tube  394  so that vacuum pressure supplied proximate to the distally extending tip  392  is not released within the carriage cavity  390 . The cutter tube  388  is advanced around the open distal end of the vacuum tube  394 , across the sample retrieval platform  396  to seal against a back seal  470  that substantially closes a proximal opening  472  into a sleeve union  474  that rotates within the cylindrical hub  384 . The sleeve union  474  has a distal end  476  engaged for rotation with the distal thumbwheel  336 . Distal and proximal O-rings  478 ,  480  reside respectively within distal and proximal races  482 ,  484  that straddle a lateral passage  486  of the sleeve union  474  to provide a degree of frictional resistance against inadvertent rotation and advantageously seal the lateral passage  486  for vacuum assistance to prolapse tissue and to retract samples. A noncircular opening  488  is centered in a distal face of the distal thumbwheel  336 . A proximal end of a probe tube  490  of the probe  98  extends through the noncircular opening  488  to receive a distal end of the cutter tube  388 . A lateral tube  492  attached along its length to the probe tube  490  communicates with the lateral passage  486  of the union sleeve  474 . The lateral tube  492  defines a lateral lumen that communicates with the a cutter lumen defined by the probe tube  490 /cutter tube  388  below the side aperture  376  through lumen holes  494  ( FIG. 9 ).  
         [0055]     The center splined driveshaft  375  that is turned by the aft end thumbwheel  63  rotates in turn a shaft  496  whose keyed distal end  498  in turn is engaged to and rotates a pinion gear  500  that is in gear engagement to a proximal spur gear  502  that forms an outer proximal circumference of the sleeve union  474 . A cylindrical distal tip  504  of the keyed distal end  498  rotates within an axle hole (not shown) in the lower shell  358 . Rotation of the aft end thumbwheel  63  thus rotates the probe  98 .  
         [0056]     A distal elbow pneumatic fitting  506  is supported in the lower shell  358  to have an upper end  508  communicating with the lateral passage  486  of the sleeve union  474  and an aft end  510  attached to a vent pneumatic conduit  512  supported by the lower shell  358 . The other end of the vent pneumatic conduit  512  is attached to a distal end  514  of a proximal elbow pneumatic fitting  516  whose lateral end  518  is open to atmosphere. Sizing of various components that vent atmospheric pressure through the lumen holes  494  from the lateral end  518  are such that a tissue sample may be withdrawn through the probe tube  490 . Yet a greater pneumatic draw of air through the vacuum hose nib  372  prior to severing a tissue sample results in a sufficient low pressure at the side aperture  376  to prolapse tissue for severing.  
         [0057]     An elongate rotation shaft  520  proximally terminates in the left splined driveshaft  382  that is supported for rotation by a left aft cylindrical bearing  522  having a race about an outer circumference that receives an O-ring  524  and is received in the aft wall  425  of the lower shell  358 . A distal end  526  of the elongate rotation shaft  520  is received for rotation in a left distal cylindrical bearing  528  having a race about an outer circumference that receives an O-ring  530  and that is received within the front wall  425  of the lower shell  358 . As the cutter carriage  418  advances to position the cutter tube  388  to slide past the side aperture  376 , the cutter spur gear  460  engages a spur gear portion  532  of the elongate rotation shaft  520 . Rotating the cutter tube  388  in proportion to an amount of rotation advantages secures an effective severing of tissue. Eliminating rotation when not severing advantageously enhances retraction of tissue sample retraction.  
         [0058]     In use, in  FIG. 11 , the localization fixture  16  has been installed into the breast coil  18 . The guidance assembly  200  has been preset for a desired insertion point, a desired axis of penetration, and a depth of penetration. After the sleeve trocar  102 /introducer obturator  104  have been inserted and imaged to confirm placement, the introducer obturator  104  is removed and the probe  98  of the biopsy device  14  is inserted, as depicted in  FIG. 12 . The shape of the sleeve trocar  102  aligns the probe  98 , visually assisted by lining up the arrow indicator  378  on the distal thumbwheel  336  with the visible angle indicator on the thumbwheel  230  of the sleeve trocar  102 . The surgeon may effect operation of the biopsy device  14  by depressing the translation rocker button  366  and aft button  368  on the keypad  62  while referencing status information about the biopsy device  14  on the display area  61 . In  FIG. 13 , the display area  61  advantageously includes a cutter position bar graph  534  having distal and proximal indications  536 ,  538  that may be compared with how many light segments  540  have been illuminated to indicate progress of the cutter tube  388  relative to the side aperture  376 . The aft button  368  may be toggled to cycle the biopsy device  14  through three modes, indicated by a position LED indicator  542 , a sample LED indicator  544 , and a clear LED indicator  546  with a corresponding label that graphically depicts operation of the biopsy device in that mode. In particular, a position mode depiction  548  illustrates that the cutter tube  388  may be advanced and retracted, for instance, closing the side aperture  376  prior to insertion of the probe  98  into the sleeve trocar  102 . In a sample mode depiction  550 , vacuum assistance is implemented, drawing sufficient air through the cutter tube  388  to prolapse tissue into the open side aperture  376  that is maintained while translating the cutter tube  388 . In a clear mode depiction  552 , vacuum is maintained while fully retracting the cutter tube  388  to retract a tissue sample. In  FIG. 14 , a marker device  548  is deployed through the sample through hole  386  in the cylindrical hub  388 .  
         [0059]     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.  
         [0060]     While the present invention has been illustrated by description of several embodiments and while the illustrative embodiments have been described in considerable detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications may readily appear to those skilled in the art.  
         [0061]     For example, while closed loop feedback sensing of a component that is related to cutter tube position has various advantages, determination of cutter position may be achieved in other ways consistent with the present invention. For instance, loading on drive components may be sensed at either full advancement and/or full retraction which are used to calibrate an estimate cutter position based on duration of a translation command.  
         [0062]     As another example, rather than discrete LED indicators and labeled depictions, applications consistent with aspects of the invention may include a graphical display (e.g., organic liquid crystal display) that is capable of interactive presentations of intuitive instrument status information. Alternatively or in addition, a touch screen capability may be incorporated to allow instrument control input as well as display.  
         [0063]     For another example, applications consistent with aspects of the present invention may be used in conjunction with different diagnostic imaging modalities (e.g., ultrasonic, computed tomography (CT).