US20050187491A1 - Breast biopsy system and methods - Google Patents

Abstract

An apparatus and method are provided for precisely isolating a target lesion in a patient's body tissue, resulting in a high likelihood of “clean” margins about the lesion when it is removed for diagnosis and/or therapy. This approach advantageously will often result in the ability to both diagnose and treat a malignant lesion with only a single percutaneous procedure, with no follow-up percutaneous or surgical procedure required, while minimizing the risk of migration of possibly cancerous cells from the lesion to surrounding tissue or the bloodstream. In particular, the apparatus comprises a biopsy instrument having a distal end adapted for entry into the patient's body, a longitudinal shaft, and a cutting element disposed along the shaft. The cutting element is actuatable between a radially retracted position and a radially extended position. Advantageously, the instrument is rotatable about its axis in the radially extended position to isolate a desired tissue specimen from surrounding tissue by defining a peripheral margin about the tissue specimen. Once the tissue specimen is isolated, it may be segmented by further manipulation of the cutting element, after which the tissue segments are preferably individually removed from the patient's body through a cannula or the like. Alternatively, the specimen may be encapsulated and removed as an intact piece.

Description

FIELD OF THE INVENTION
• The present invention relates to methods and devices for removing tissue samples, and more specifically to improved instruments and methods for acquiring soft body tissue.
BACKGROUND OF THE INVENTION
• It is often desirable and frequently necessary to sample or remove a portion of tissue from humans and other animals, particularly in the diagnosis and treatment of patients with cancerous tumors, pre-malignant conditions, and other diseases or disorders.
• Typically, in the case of cancer, particularly cancer of the breast, there is a great emphasis on early detection and diagnosis through the use of screening modalities, such as physical examination, and particularly mammography, which is capable of detecting very small abnormalities, often nonpalpable. When the physician establishes by means of a mammogram or other screening modality, such as ultrasound, that suspicious circumstances exist, a biopsy must be performed to capture tissue for a definitive diagnosis as to whether the suspicious lesion is cancerous. Biopsy may be done by an open or percutaneous technique. Open biopsy, which is an invasive surgical procedure using a scalpel and involving direct vision of the target area, removes the entire mass (excisional biopsy) or a part of the mass (incisional biopsy). Percutaneous biopsy, on the other hand, is usually done with a needle-like instrument through a relatively small incision, blindly or with the aid of an artificial imaging device, and may be either a fine needle aspiration (FNA) or a core biopsy. In FNA biopsy, individual cells or clusters of cells are obtained for cytologic examination and may be prepared such as in a Papanicolaou smear. In core biopsy, as the term suggests, a core or fragment of tissue is obtained for histologic examination which may be done via a frozen section or paraffin section.
• The type of biopsy utilized depends in large part on circumstances present with respect to the patient, including the location of the lesion(s) within the body, and no single procedure is ideal for all cases. However, core biopsy is extremely useful in a number of conditions and is being used more frequently by the medical profession.
• A very successful type of image guided percutaneous core breast biopsy instrument currently available is a vacuum-assisted automatic core biopsy device. One such successful biopsy device is shown and disclosed in U.S. Pat. No. 5,526,822 to Burbank et al, expressly incorporated by reference herein. This device, known commercially as the MAMMOTOME® Biopsy System, which is available from Ethicon Endo-Surgery, Inc., a division of Johnson & Johnson, has the capability to actively capture tissue prior to cutting the tissue. Active capture allows for sampling through non-homogeneous tissues. The device is comprised of a disposable probe, a motorized drive unit, and an integrated vacuum source. The probe is made of stainless steel and molded plastic and is designed for collection of multiple tissue samples with a single insertion of the probe into the breast. The tip of the probe is configured with a laterally disposed sampling notch for capturing tissue samples. Orientation of the sample notch is directed by the physician, who uses a thumbwheel to direct tissue sampling in any direction about the circumference of the probe. A hollow cylindrical cutter severs and transports tissue samples to a tissue collection chamber for later testing.
• While this type of system functions very well as a core biopsy device, there are occasions when it may be useful to have the capability of acquiring a relatively large intact tissue sample. One such core biopsy device is disclosed in U.S. Pat. No. 5,111,828, to Komberg et al., also expressly incorporated by reference herein. In the device disclosed by Komberg et al., the tissue receiving port is disposed at the distal end of the device and is oriented axially rather than laterally. A disadvantage of this type of device, however, is the inability to acquire a tissue sample having a cross-section larger than that of the cannula through which the sample will be removed. Additionally, it is difficult, using such a device, which obtains cylindrical shaped specimens, to determine whether an entire lesion of interest is being removed or whether a further procedure will be necessary. This is particularly true because most lesions of interest are typically spherical in shape, having a diameter of approximately 1 cm. The only way one can tell whether the entire lesion has been removed using the Komberg technique is to remove and examine the specimen, determining whether each of the margins of the specimen is “clean”, meaning that there is no evidence of lesion, or “dirty”, meaning that lesion is evident right to the edge of the specimen. Of course, if one or more specimen margins is “dirty”, it is almost a certainty that a portion of the lesion remains in the patient, and if the biopsy test results on the lesion are positive, a further surgical procedure will be indicated.
• It would be desirable, therefore, to have an apparatus and method for isolating a target lesion, with a sufficient border around and beyond the lesion that the likelihood of “clean” margins is relatively high. It would further be advantageous to have an apparatus and method available for initially isolating the entire target lesion, by cutting a swath completely about the lesion to cut off its blood supply; after which a further procedure is undertaken to remove it from the patient's body. This approach would help to minimize the migration of possibly cancerous cells from the lesion to surrounding tissue or bloodstream during the removal procedure.
SUMMARY OF THE INVENTION
• The present invention addresses the foregoing problems by providing such an apparatus and method for precisely isolating a target lesion, resulting in a high likelihood of “clean” margins. This advantageously will often result in the ability to both diagnose and treat a malignant lesion with only a single percutaneous procedure, with no follow-up percutaneous or surgical procedure required, while minimizing the risk of migration of possibly cancerous cells from the lesion to surrounding tissue or the bloodstream.
• More particularly, in one aspect of the invention, a biopsy instrument is provided for retrieving body tissue, which instrument has a longitudinal axis. The instrument comprises a distal end adapted for entry into a patient's body, a shaft disposed along the axis, and a cutting element disposed along the shaft. The cutting element is actuatable between a radially retracted position and a radially extended position. Advantageously, the instrument is rotatable about its axis in the radially extended position to isolate a desired tissue specimen from surrounding tissue by defining a peripheral margin about the tissue specimen. Once the tissue specimen is isolated, it May be segmented by further manipulation of the cutting element, after which the tissue segments are preferably individually removed from the patient's body through a cannula or the like. Alternatively, the specimen may be encapsulated and removed as an intact piece.
• In another aspect of the invention, an instrument is provided for retrieving body tissue, having a longitudinal axis and comprising a distal end adapted for entry into a patient's body. The instrument further comprises an element for encapsulating a tissue specimen so that it may be withdrawn as a single unit from the patient's body. The encapsulating element preferably comprises a plurality of bands disposed along the instrument axis, each of which are actuatable between a radially retracted position and a radially extended position.
• In yet another aspect of the invention, a method is disclosed for retrieving a tissue specimen from a patient's body, comprising the steps of inserting an instrument having a distal end, a longitudinal axis, and an axially disposed cutting element, into the patient's body, so that a distal end is disposed in a tissue region from which the tissue specimen is to be taken. The cutting element is radially expanded so that a portion thereof is radially outwardly spaced from the axis of the instrument. Once the cutting element is radially expanded, it is rotated about the axis to cut the tissue and create a peripheral boundary about the tissue specimen, to isolate the tissue specimen from surrounding tissue in the tissue region.
• The invention, together with additional features and advantages thereof, may best be understood by reference to the following description taken in conjunction with the accompanying illustrative drawing.
BRIEF DESCRIPTION OF THE DRAWING
• FIG. 1 is a perspective view of the distal end of one preferred embodiment of the inventive tissue retrieval instrument;
• FIG. 2 is a perspective view illustrating the distal end of a monopolar embodiment of the inventive tissue retrieval instrument shown inFIG. 1;
• FIG. 3 is a perspective view similar to that ofFIG. 2, illustrating the distal end of a bipolar embodiment of the inventive tissue retrieval instrument shown inFIG. 1;
• FIG. 4 is a cutaway view from the side illustrating the internal construction of a presently preferred proximal drive unit for operating the inventive tissue retrieval instrument;
• FIG. 5 is a perspective view from the top illustrating the proximal drive unit ofFIG. 4, with the top portion of the housing removed in order to show portions of its internal construction;
• FIG. 6 is a perspective view from the proximal end illustrating the proximal drive unit ofFIGS. 4 and 5, with the top portion of the housing removed in order to show portions of its internal construction;
• FIG. 7 is a perspective view from the distal end illustrating the proximal drive unit ofFIGS. 4-6, with the top portion of the housing removed in order to show portions of its internal construction;
• FIG. 8 is a schematic view illustrating the distal end of the instrument ofFIG. 1 disposed in a tissue region from which target tissue is to be retrieved, wherein the distal cutting element is deployed in a first position for isolating a first segment of a target tissue specimen from surrounding tissue;
• FIG. 9 is a schematic view similar toFIG. 8, wherein the distal cutting element is deployed in a second position for isolating a second segment of the target tissue specimen from surrounding tissue;
• FIG. 10 is a schematic view similar toFIGS. 8 and 9, wherein the distal cutting element is deployed in a third position for isolating a third segment of the target tissue specimen from surrounding tissue;
• FIG. 11 is a perspective view illustrating the distal end of a second preferred embodiment of the inventive tissue retrieval instrument;
• FIG. 12 is a perspective cutaway view of the distal end of the embodiment ofFIG. 11, illustrating the internal construction thereof, including tissue wrapping and cutting elements in their stored position;
• FIG. 13 is a perspective cutaway view similar to that ofFIG. 12, wherein the sheath has been retracted in order to deploy the tissue wrapping and cutting elements shown inFIG. 12;
• FIG. 14 is a side schematic view of the distal end of the embodiment ofFIGS. 11-13, illustrating the deployment of the tissue wrapping and cutting elements shown inFIG. 12;
• FIG. 15 is a perspective view illustrating the tissue wrapping and cutting elements ofFIGS. 12 and 14 in their fully deployed position;
• FIG. 16 is a side view showing the deployed tissue wrapping and cutting elements after the distal end of the instrument has been rotated to twist the wrapping and cutting elements in order to wrap a target tissue sample;
• FIG. 17 is a perspective, schematic view of an alternative embodiment of the distal end of the inventive tissue retrieval instrument, wherein the cutting element of the instrument is in a retracted position;
• FIG. 18 is a perspective, schematic view similar toFIG. 17, illustrating the cutting element in a deployed position for creating cylindrical tissue segments; and
• FIG. 19 is a perspective, schematic view similar toFIGS. 17 and 18, illustrating the cutting element in a deployed position for creating tissue segments of varying heights.
DESCRIPTION OF THE INVENTION
• Referring now more particularly toFIG. 1, there is shown thedistal end12 of a first preferred embodiment of an inventive tissue retrieval orbiopsy instrument10. Thedistal end12 preferably comprises a disposable wand portion, including adistal tip14. Thetip14 may comprise a conventional trocar tip, or, preferably, may include an electrosurgical (RF) element orwire16 which may be energized by a conventional electrosurgical generator (not shown) in order to facilitate tissue cutting and consequent advancement of theinstrument10 to a predetermined tissue site in the patient's body.
• Proximally of thetip14 is ashaft18, preferably lying along an axis19 (FIG. 1) of the instrument, on which is disposed a cutting element orwire20. Thiswire20 is disposed axially along the length of theshaft18 in its retracted position (not shown), but may be deployed radially outwardly, as shown inFIG. 1. Theelement20 is preferably comprised of a wire or rectangular band fabricated of memory metal such as Nitinol, though stainless steel, tungsten, or other biocompatible materials could also be employed, if desired. The cuttingelement20 acts as an electrosurgical cutter, energizable by means of RF energy provided by the electrosurgical generator discussed supra; Theinstrument10 may be monopolar, as illustrated inFIG. 2, with the cuttingelement20 comprising the active electrode and a return electrode spaced from theinstrument10 and most typically being disposed on the patient's skin in the form of a patch electrode on the thigh or back. Alternatively, theinstrument10 may preferably be bipolar, as illustrated inFIG. 3, with the cutting element comprising the active electrode and areturn electrode22 being disposed on the instrument in close proximity to the active electrode, such as along theshaft18. With such an arrangement, a layer ofinsulation23 is disposed between the return electrode (comprising a major portion of the surface area of the shaft18) and the portion of the shaft adjacent to the active electrode, which receives the cuttingelement20 in its retracted position. The bipolar embodiment is generally preferred because of a greater safety factor and lower power requirements.
• A plurality of cuttingwires20 may be employed if desired, preferably spaced circumferentially about theshaft18. In some embodiments, it may be preferably to have webs between the cutting elements, to create a “sail” rather than entire distinct separate cutting elements.
• Referring now more particularly toFIGS. 4-7, a proximalreusable driver portion24 for the distal end ordisposable wand portion12 is shown. Thedriver portion24 is preferably disposed on astereotactic rail26, in known fashion, for guidance of theinstrument10 to a predetermined tissue site using known imaging techniques. Such stereotactic imaging systems are available, for example, from Fischer, Inc. or Lorad, Inc. Alternative imaging systems, such as mammographic, ultrasonic, CT, MRI guidance systems may be used in place of a stereotactic system, if desired. Additionally, the instrument may be guided to the lesion site using an articulating arm system or manually, rather than on a stereotactic rail.
• Thereusable driver portion24 comprises ahousing28 within which is disposed a coaxial arrangement comprising anouter sheath30, theshaft18, and arod32 which is attached at its distal end to thecutter element20. Aknob34 is rotatably attached to theshaft18 through agearing system35 to rotate theshaft18 as desired, for the purpose of circumferentially orienting and rotating the cuttingelement20. Threelevers36,38, and40 extend outwardly throughslots42,44, and46, respectively, in the side of thehousing28. Thefirst lever36 is actuatable to slide thesheath30 axially both proximally and distally, for a purpose to be described hereinbelow. Thesecond lever38 is actuatable to move theshaft18 axially in distal and proximal directions, as desired. Thethird lever40 is actuatable to move therod32 axially in distal and proximal directions, as desired. Since therod32 is attached at its distal end to the proximal end of thewire cutter20, movement of therod32 in an axial direction also causes the proximal end of thewire cutter20 to move in an axial direction. Since the distal end of thecutter20 is anchored to theshaft18, movement of the proximal end of thecutter element20 in a distal direction causes the midportion of the cuttingelement20 to bow radially outwardly to a radially expanded position, as shown in any ofFIGS. 1-3, while movement of the proximal end of thecutter element20 in a proximal direction causes the midportion of thecutter element20 to retract radially to its stowed position, disposed linearly along the axial length of theshaft18, preferably within a recess48 (FIG. 1).
• An advantageous feature of the invention is the employment of a series ofstops50 in thesecond slot44, and a series ofstops52 in thethird slot46, as illustrated inFIGS. 5-7. The stops50 enable thesecond lever38 to be actuated to a plurality of discrete axial positions, which in turn permits theshaft18 to be actuated to a corresponding plurality of discrete axial positions for fine tuning the axial position of the electrosurgical cuttingelement20. Similarly, thestops52 enable thethird lever40 to be actuated to a plurality of discrete axial positions, which in turn permits the electrosurgical cuttingelement20 to be radially extended to a corresponding plurality of radially extended positions, for a purpose to be described more fully hereinbelow.
• With reference now more particularly toFIGS. 8-10, the operation of the first preferred embodiment of the inventive device will be explained. Initially, when it is determined that either a diagnostic or therapeutic biopsy procedure is indicated, the distaldisposable wand portion12 of theinstrument10 will be moved axially to a position wherein the distal tip is adjacent to and preferably within atarget lesion54, using thestereotactic rail26 and associated imaging system. During this process step, wherein gross linear movement of thewand12 is controlled by therail system26, the electrosurgical cuttingelement16 on thedistal tip14 is energized to pierce and cut through the patient'sbody tissue56 to permit distal advancement of thewand12 to the region surrounding thelesion54.
• Once thedistal tip14 is generally in the desired position adjacent to or within thetarget lesion54, using thestereotactic rail26, thesecond lever38 is actuated to provide fine tuning of the axial position of thedistal tip14 relative to thelesion54, by moving theshaft18 axially to a desired position, and securing thelever38 in anappropriate stop50 to maintain the desired axial position. This fine axial adjustment of the axial movement of theshaft18 is performed using appropriate imaging equipment The objective of this process step is to ensure that the distal end of thecutting wire20 is disposed distally of the distal peripheral edge of thelesion54, while at the same time the proximal end of thecutting wire20 is disposed proximally of the proximal peripheral edge of thelesion54. This will ensure the ability to isolate theentire lesion54 during the cutting procedure, with sufficient margins to minimize the chance that any portion of10 the lesion inadvertently remains behind in the patient's body following removal thereof.
• When thedistal tip14 is in the precise position desired by the practitioner,first lever36, which is normally disposed in a first detent58 (FIGS. 5 and 6) in thefirst slot42, is actuated proximally until it rests in a second detent60 (FIG. 5) in thefirst slot42.
• This action retracts thesheath30 proximally a sufficient distance to partially uncover the cuttingelement20. It should be noted, however, that in some circumstances it may be desirable to fully retract the sheath, so that theentire cutting element20 is released, in order to create a different cutting geometry. In such an instance, a detent61 (FIG. 7) is provided within theslot42 to accommodate thelever36 in the fully proximal position necessary to achieve full axial retraction of the sheath. Additional intermediate detents60 (not shown) may be provided to retract the sheath to intermediate positions corresponding to various partial radial extension positions of the cutting element.
• After thesheath30 is retracted as desired, thethird lever40 may then be actuated distally along thethird slot46 to anintermediate stop52, thereby causing therod32, and therefore the proximal end of the cuttingelement20, to move axially a distance equivalent to that traversed by thelever40. This, of course, results in the partial radial expansion of the cuttingelement20 to an arched or bowed configuration as shown inFIG. 8. The extended configuration of the cuttingelement20 may define, when rotated about the instrument axis, a spherical cutting volume, as shown, or it may be configured to define an elliptical or toroidal cutting volume when the cutting element is rotated about theinstrument axis19, rather than a spherical volume.
• Of course many other mechanisms for radially expanding thecutting element20 may be utilized as well, within the scope of the invention. For example, since thewire20 is preferably fabricated of a shaped memory or superelastic material, the proximal retraction of thesheath30, and resultant release of thewire20, may be sufficient to cause thecutting wire20 to radially expand to its desired position.
• Once the cuttingelement20 is partially radially expanded as described supra, an inner portion of thetarget lesion54 is isolated from surrounding tissue. To complete this step, the cuttingelement20 is energized by the electrosurgical generator (not shown), after which theknob34 is rotated, either manually or via a motorized drive mechanism, to rotate the cuttingelement20 through a 360 degree arc. This rotational cutting action functions to completely sever the inner portion of the tissue sample from the surrounding tissue, thereby cutting off all blood supply to the inner tissue sample. Alternatively, if desired, the cuttingelement20 may be simultaneously rotated and moved axially, by moving theshaft18 axially, in order to create a “corkscrew”-shaped tissue segment.
• Once this initial isolation step is completed, the cutting element orwire20 is preferably further radially extended to the position shown inFIG. 9. This is accomplished by sliding thelever36 proximally to anotherdetent60 to further proximally retract thesheath30. Then, thethird lever40 may be axially slid distally to another stop ordetent52 to further radially extend thecutting wire20. Once radially positioned, the cuttingelement20 is energized by the electrosurgical generator, after which theknob34 is rotated to rotate the cuttingelement20 through a 360 degree arc. This rotational cutting action functions to completely sever a second segment of the tissue sample from the surrounding tissue, thereby cutting off all blood supply to this segment as well.
• These steps may be repeated as many times as desired, in order to ensure that the tissue sample is segmented for efficient removal from the patient's body. Ultimately, however, a final cut is preferably made, by fully retracting theouter sheath30, using theslide lever36, and fully extending thecutting wire20, using theslide lever40, so that the cuttingelement20 extends radially beyond the periphery of thetarget lesion54, as illustrated inFIG. 10. The cutting element is then energized with RF energy, in the same manner as previously, after which theknob34 is rotated to rotate thecutting wire20 through a complete arc about theaxis19. At this point, theentire lesion54 should be completely isolated from surrounding tissue, with a sufficient margin about the outer periphery thereof to ensure successful removal of the entire lesion.
• During the foregoing segmentation process, if the cuttingelement20 remains charged by RF energy during the stepwise radial extension process, the outer tissue rings will be further segmented radially.
• Other segmentation approaches may be advantageously utilized as well, if desired. For example, rather than segmenting the tissue sample circumferentially, from the inside out, the tissue sample may be segmented circumferentially from the outside in, i.e. by making an outer circumferential cut (FIG. 10), then partially retracting the cuttingelement20 and cutting additional layers, as shown inFIGS. 8 and 9. Alternatively, the tissue may be sectioned by extending and retracting the cuttingelement20 radially, akin to “sectioning an orange”. Additional radially oriented cutting elements could be employed as well to further segment the tissue.
• An alternative approach to segmenting the tissue specimen to be retrieved is illustrated in the embodiment shown inFIGS. 17-19. In this embodiment, wherein like elements to those in the embodiment ofFIG. 1 are designated by like reference numerals, succeeded by the letter a, there is shown a tissue retrieval orbiopsy instrument10a, having adistal tip14awith an electrosurgical element or wire16afor cutting tissue and thereby permitting advancement of the instrument into a patient's body. A shaft orcannula18ais disposed along anaxis19aof the instrument. Alongitudinal slot66 is disposed axially along a portion of the length of thecannula18a.A cutting element or wire20a,which is preferably an electrosurgical cutting element, is disposed so as to be extendable from and retractable into the slot. The cutting element is shown in a retracted position inFIG. 17, and in an extended position inFIGS. 18 and 19.
• In operation, once theinstrument10ahas been positioned so that the distal tip is adjacent to a lesion to be removed, in the manner described supra with respect to the embodiment ofFIG. 1, the cutting element20ais charged with RF energy from a proximally disposed electrosurgical generator (not shown). Then, the cutting element20ais radially extended by the practitioner, using a proximal control mechanism (not shown), to a position as shown, for example, inFIG. 18. Once extended, the cutting element is moved axially in a proximal direction along theslot66, as illustrated by thearrow68 and the phantom images of the cutting element20a, in order to isolate a generally cylindrical tissue segment, as thecannula18ais rotated about itsaxis19asimultaneously.
• FIG. 19 illustrates a procedure similar to that illustrated inFIG. 18, except that while the cutting element20ais being axially moved in a proximal direction as shown byarrows70, it is also deployed to various radial heights, in order to create a variable height cut.
• Once segmentation of the tissue sample has been completed, whichever embodiment has been employed, each tissue segment can be withdrawn using a suitable retrieval apparatus. Preferably, the tissue segments are withdrawn through a cannula, such as thesheath30, using such means as a suction grasper, flexible mechanical graspers, an auger conveyor, a prickly bristle or brush grasper, a wire retrieval basket, or the like.
• The foregoing procedure and apparatus may be used for either a diagnostic or a therapeutic purpose. It is particularly advantageous for a diagnostic procedure because the resultant incision from the procedure will not substantially exceed in length the diameter of the cannula. On the other hand, a second preferred embodiment, illustrated inFIGS. 11-16, is particularly suited to a therapeutic procedure, wherein it is highly desired to ensure that the entire lesion of interest is removed in one step, without segmenting that lesion within the body. This approach emphasizes maximum safety, in that only a single procedure is necessary, assuming the tissue sample margins are clean, and the incision necessary to remove the intact tissue sample is of the minimum size necessary to remove the sample. With this procedure, there is also a somewhat reduced risk of cell migration from the specimen to the surrounding tissue, since as described below, the specimen is encapsulated as soon as it is isolated and then promptly removed. No segmentation of the specimen occurs within the patient's body.
• Referring now toFIGS. 11-14, wherein like elements to those in the first embodiment are identified by like reference numerals, followed by the letter “b”, there is shown the distal end ordisposable wand portion12bof an instrument10b. Theportion12bincludes adistal tip14b,which may be constructed in a manner similar to that oftip14 inFIG. 1, ashaft18b, and asleeve30b.Disposed in a radially retracted orientation in a recess48bof theshaft18bare a plurality of encapsulation elements orbands72, one of which also comprises a singleelectrosurgical cutting element20b.For the purposes of the invention it is unimportant which of theencapsulation elements72 may be charged by means of RF energy to form an electrosurgical cutter, and in certain instances it may be advantageous to employ a plurality of cutting elements. Each of theencapsulation elements72 and the cuttingelement20bare attached at their distal ends to the distal end of theshaft18b, at its connection with thedistal tip14bof the instrument10b,which connection is preferably accomplished by means of akeyway74.
• The proximal end of the instrument10bmay be substantially the same as that for theinstrument10, illustrated inFIGS. 4-7, comprising a reusable driver portion having an actuator for axially moving thesheath30bbetween proximal and distal positions, a linear actuator for axially moving theshaft18b,an actuator for rotationally moving theshaft18b,and an actuator for axially moving the proximal ends of theencapsulation elements72 and cuttingelement20b,in order to radially extend and retract each of theelements72 and20b,as illustrated inFIGS. 14-16.
• In operation, as with the first embodiment ofFIG. 1, when it is determined that either a diagnostic or therapeutic biopsy procedure is indicated, the distaldisposable wand portion12bof the instrument10bwill be moved axially to a position wherein the distal tip is adjacent to and distally of a target lesion, using thestereotactic rail26 and associated imaging system. During this process step, wherein gross linear movement of thewand12bis controlled by therail system26, the electrosurgical cutting element (not shown) on thedistal tip14bis energized to pierce and cut through the patient's body tissue to permit distal advancement of thewand12bto the region surrounding the lesion.
• Once thedistal tip14bis generally in the desired position adjacent to the target lesion, using thestereotactic rail26, thesecond lever38 is actuated to provide fine tuning of the axial position of thedistal tip14brelative to the lesion, by moving theshaft18baxially to a desired position, and securing thelever38 in anappropriate stop50 to maintain the desired axial position. This fine axial adjustment of the axial movement of theshaft18bis performed using appropriate imaging equipment. The objective of this process step is to ensure that the distal end of thecutting wire20bis disposed distally of the distal peripheral edge of the lesion, while at the same time the proximal end of thecutting wire20bis disposed proximally of the proximal peripheral edge of the lesion. This will ensure the ability to isolate the entire lesion during the cutting procedure, with sufficient margins to minimize the chance that any portion of the lesion inadvertently remains behind in the patient's body following removal thereof.
• When thedistal tip14bis in the precise position desired by the practitioner,first lever36, which is normally disposed in a first detent58 (FIGS. 5 and 6) in thefirst slot42, is actuated proximally until it rests in a second detent60 (FIG. 7) in thefirst slot42. This action retracts thesheath30bproximally a sufficient distance to completely uncover the cuttingelement20band associatedencapsulation elements72. Thethird lever40 may then be actuated distally along thethird slot46 to thedistal-most stop52, thereby causing therod32, and therefore the proximal ends of the cutting element20aandencapsulation elements72, to move axially a distance equivalent to that traversed by thelever40. This, of course, results in the radial expansion of the cuttingelement20bandencapsulation elements72 to an arched or bowed configuration as shown inFIG. 14, wherein the cuttingelement20b.defines a peripheral boundary which lies radially beyond the peripheral boundary of the lesion, as in the case of the first embodiment shown inFIG. 8. Again, it should be noted that the cutting element and encapsulation elements need not be fully extended, especially if an ellipsoidal or toroidal cutting geometry is desired, in which caseintermediate stop61 is utilized.
• Once the cuttingelement20band associatedencapsulation elements72 are radially expanded as described supra, it is time to isolate the target lesion from surrounding tissue. Advantageously, a spherical or toroidal tissue sample having a radius of at least 15 mm may be defined and isolated by rotating the cuttingelement20babout the axis of theshaft18b.Theencapsulation elements72 will also be rotated during this process, but their function is not yet important. To complete the isolation step, the cuttingelement20bis energized by the electrosurgical generator (not shown), after which theknob34 is rotated, either manually or via a motorized drive mechanism, to rotate theshaft18b,and thus the cuttingelement20bthrough a 360 degree arc. This rotational cutting action functions to completely sever the tissue sample from the surrounding tissue, thereby cutting off all blood supply to the tissue sample (and thus from the lesion, which should be completely contained within the tissue sample).
• After the isolation step is completed, the isolated tissue sample may be retrieved from the patient'sbody56. This retrieval step may be accomplished in a number of ways, but it is the objective in connection with the illustrated embodiment to encapsulate and remove the isolated tissue sample in one piece. Accordingly, as is illustrated inFIGS. 15 and 16, continued rotation of theshaft18b, once the isolation step has been completed, preferably with the cuttingelement20bde-energized, will twist and tighten the encapsulatingelements72 and the cuttingelement20babout the tissue sample (not shown). As theshaft18bis rotated, and the encapsulatingelements72 radially retracted and twisted, they will function to deform the tissue sample radially so that it is more compact and more securely retained within the spaced defined by the encapsulatingelements72.
• Once the tissue sample has been fully encapsulated, the tissue sample may be removed from the patient's body. Advantageously, since the tissue sample is larger in cross-section than the cross-section of thesheath30b,the inventors have developed an inventive approach for removal thereof which results in minimum trauma and incision size for the patient while still permitting the removal of an intact specimen. To remove the specimen, thesheath30bis retracted proximally, following which the cuttingelement20bis again energized by the electrosurgical generator. Theshaft18b,with the tissue specimen encapsulated thereabout, is then proximally withdrawn by the practitioner, with the cuttingelement20bfunctioning to cut through the tissue necessary to create a passage for exit of the sample. Once the unit, including the shaft and encapsulated tissue mass, is completely withdrawn from the body, the incision created by the cuttingelement20bupon withdrawal from the body may be adhesively closed, with minimal required follow-up care and scarring.
• Many alternative embodiments may be used to accomplish the method outlined supra, which essentially involves isolating the tissue mass from surrounding tissue, encapsulating the tissue mass in place about a shaft, then removing the encapsulated tissue mass and shaft from the body by energizing an RF electrosurgical cutter to cut its way out, without the need for a cannula or pre-existing incision. For example, a plurality of cutting elements could be employed, or a separate cutting element could be disposed on the shaft. An important aspect of the invention, of course, is a relatively high likelihood of acquiring the entire lesion of interest in a single therapeutic procedure, without the need for follow-up surgery.
• While this invention has been described with respect to various specific examples and embodiments, it is to be understood that the invention is not limited thereto and that it can be variously practiced within the scope of the following claims.

Claims (5)

1. A biopsy instrument for retrieving body tissue, having a longitudinal axis and comprising:

a distal end adapted for entry into a patient's body; and

a cutting element disposed on said instrument, said cutting element being actuatable between a radially retracted position and a radially extended position, relative to said axis, and being movable in said radially extended position to isolate a desired tissue specimen from surrounding tissue by defining a peripheral margin about said tissue specimen.

2-39. (canceled)

40. An excisional biopsy method for soft tissue, comprising:

a. inserting a generally tubular member into the tissue which has a cutting tool adapted to selectively bow away from the tubular member and which has a tissue collection device near a distal tip of the tubular member;

b. rotating the tubular member;

c. selectively varying a degree of bowing of the cutting tool;

d. collecting tissue severed by the cutting tool in the tissue collection device; and

e. retracting the tubular member from the soft tissue.

41. The method ofclaim 40, wherein the rotating step is carried out by manually rotating the tubular member.

42. The method ofclaim 40, wherein the extension of the cutting tool is controlled by selectively and manually pushing and retracting a proximal end of the cutting tool in the distal and proximal directions, respectively.

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