Abstract:
A method for operating a biopsy device to acquire at least one tissue sample from a body of a living being, including retracting a sample-receiving device through a hollow needle to a sample removal position, a tissue sample being simultaneously transported to the sample removal position by the sample-receiving device; operatively connecting a liquid supply unit to a cavity of the sample-receiving device when the sample-receiving device is at the sample removal position; and delivering a lateral flow of a flushing liquid from the liquid supply unit to the cavity of the sample-receiving device to facilitate a lateral tissue sample ejection from the cavity.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. application Ser. No. 11/632,014 filed Nov. 13, 2007, which is a U.S. national phase of International Application No. PCT/DK2005/000485, filed Jul. 8, 2005, which claims the benefit of U.S. Provisional Application No. 60/586,290, filed Jul. 9, 2004, U.S. Provisional Patent Application No. 60/625,127, filed Nov. 5, 2004, and U.S. Provisional Patent Application No. 60/625,128, filed Nov. 5, 2004, each of which is incorporated herein by reference in its entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to a biopsy device for harvesting tissue samples of human or animal bodies. The invention is particularly, but not exclusively, aimed at percutaneous biopsy, in which it is desirable to gain access to suspect tissue mass in a minimally invasive manner. The invention is particularly concerned with aspects of ejecting a harvested body tissue sample from a sample-receiving device, by means of which the harvested body tissue sample is withdrawn from a human or animal patient. 
       BACKGROUND OF THE INVENTION 
       [0003]    For diagnostic purposes it may be desirable to obtain a tissue sample of a human or animal body for in vitro cytological and/or histological examination. Tissue sampling may be performed either as an open or a percutaneous technique. n the open technique, either the entire suspect mass (excisional biopsy) or part of the suspect mass (incisional biopsy) is removed. Access to the lesion as well as removal is generally obtained with the use of scalpels, and open biopsies are a reliable—if quite invasive—means of obtaining tissue samples. 
         [0004]    In the percutaneous technique, a needle is used to gain access to the suspect tissue mass in a less invasive fashion. This needle may be hollow, permitting the aspiration of single cells and tissue fragments into a lumen by application of a vacuum (aspiration biopsy). Alternatively, larger tissue cores may be harvested by means of a needle containing an inner movable trocar with a notch formed to receive tissue cores, and an outer, slidable cannula with a sharpened distal end used to sever these cores from the surrounding tissue (core needle biopsy). By advancing the inner trocar into a suspect lesion and subsequently advance the outer slidable cannula to cover the notch completely, a tissue sample may be severed and held in the notch. The needle may then be retracted from the body of the patient, and the tissue sample may be collected and stored for further analysis. 
         [0005]    Core needle biopsy devices have been preferred tools among physicians due to their simple use and versatility. The core needle devices may be applied to a broad range of different tissues and different anatomical locations, and provide the pathologist with samples suitable for histological analysis for the accurate diagnosing and staging of suspect masses. 
         [0006]    Obtaining the largest possible sample size is an important objective in the harvesting of core tissue samples. Prior art biopsy systems have used vacuum to engage and draw tissue towards the notch or tissue-receiving chamber or basket of the biopsy device prior to cutting. Thus, tissue sample sizes may be significantly increased with a given biopsy needle diameter or larger samples extracted with the same needle diameter to improve diagnostic accuracy. 
         [0007]    Another well-known prior art technique to increase sample size is to harvest multiple samples in order to obtain sufficient tissue for a reliable diagnosis. To do so with the aspiration, core needle biopsy devices or single-action vacuum-assisted devices is only possible through multiple device insertions, resulting in increased patient discomfort, time consumption and risk of bleeding. 
         [0008]    In the area of breast biopsies, this problem has been solved with the development of biopsy systems enabling the operator to extract multiple samples with a single biopsy device insertion. These biopsy devices generally apply vacuum to engage and aspirate a suitable amount of tissue into a hollow portion of the instrument. The power and vacuum supply units pertaining to those multiple biopsy devices are housed in separate vacuum stations that require carts for transportation as well as hoses and leads to function properly. The physical connection between the biopsy device and the accompanying vacuum/power supply units means that the freedom of movement of the operator or physician is limited, and auxiliary devices furthermore take up storage and floor space. 
         [0009]    In prior art biopsy systems and devices tissue sample extraction, ejection and subsequent storage of the individual tissue samples have been accomplished by a number of different methods. Some biopsy devices comprise mechanical extraction and ejection of extracted tissue samples, as illustrated in U.S. Pat. No. 5,526,822. The biopsy device captures and holds the tissue sample in a lumen of an inner, rotating cutting cannula that is retractable to a point outside the anatomy of the patient. An ejector pin is utilized to push the captured tissue sample out of the lumen of the cannula. 
         [0010]    Other prior art biopsy devices feature vacuum-driven extraction and ejection of tissue samples. U.S. Pat. No. 6,638,235 discloses a biopsy device with an inner, rotating cutting cannula capable of harvesting multiple tissue samples in a single cannula insertion. The device reduces operator involvement by enabling the automatic extraction and collection of multiple tissue samples in a collection chamber placed outside the anatomy of the patient. 
         [0011]    Tissue samples are extracted from the point of sampling and moved through the inner lumen of the cutting cannula to the collection chamber by means of a vacuum that is drawn through the collection chamber and the inner lumen of the cutting cannula. In the sampling, collection and storing of some types of tissue samples, such as prostate tissue samples, it is desirable that extracted individual tissue cores or samples are kept apart if a subsequent diagnosis is to be valid. 
       SUMMARY OF THE INVENTION 
       [0012]    It is an object of preferred embodiments of the present invention to provide a biopsy device and a method that may permit sampling, preferably in an automatic manner. It is a further object of preferred embodiments of the invention to provide a biopsy device and a method, which allow for storing of individually separated tissue samples in a preserving agent. It is a still further object of preferred embodiments of the invention to provide a biopsy device and a method, which allow for convenient penetration of suspect tissue mass. It is a still further object of preferred embodiments of the invention to provide a biopsy device and a method, which allow for convenient severing of a tissue sample. It is a still further object of preferred embodiments of the invention to provide a biopsy device and a method, which facilitate handling of acquired tissue samples by a physician. It is a still further object of preferred embodiments of the invention to provide a biopsy device, which is conveniently maneuverable by a physician. 
         [0013]    The invention, in one form thereof, is directed to a self-contained hand-held biopsy device for harvesting at least one tissue sample from a body of a living being. The self-contained hand-held biopsy device includes a hollow needle having a distal end portion with a circumferential cutting edge. A sample-receiving device is received in the hollow needle. The sample-receiving device has a tapered distal tip configured to penetrate tissue and a cavity configured to receive a tissue sample. The sample-receiving device is configured to move in the hollow needle between a first extended position and a second retracted position. A transport device is coupled to the sample-receiving device. The transport device is configured to move the sample-receiving device relative to the hollow needle. A liquid supply unit is configured to carry and supply a flushing liquid. The liquid supply unit is configured to operatively connect to the cavity of the sample-receiving device when the sample-receiving device is in the second retracted position and is configured to deliver a flow of the flushing liquid to the cavity to facilitate tissue sample ejection from the cavity. The liquid supply unit is disconnected from the cavity of the sample-receiving device when the sample-receiving device is in the first extended position. 
         [0014]    The invention, in another form thereof, is directed to a self-contained hand-held biopsy device for harvesting at least one tissue sample from a body of a living being. The self-contained hand-held biopsy device includes a disposable unit and a handle unit configured to releasably mount the disposable unit. The disposable unit includes a hollow needle having a distal end portion with a circumferential cutting edge; a sample-receiving device received in the hollow needle, the sample-receiving device having a tapered distal tip and a cavity configured to receive a tissue sample, the sample-receiving device being configured to move in the hollow needle between a first extended position and a second retracted position; and a transport device coupled to the sample-receiving device, the transport device being configured to move the sample-receiving device relative to the hollow needle. The handle unit includes a drive unit configured to drive the transport device, and a liquid supply unit configured to carry and supply a flushing liquid. The liquid supply unit is configured to operatively connect to the cavity of the sample-receiving device when the sample-receiving device is in the second retracted position and is configured to deliver a flow of the flushing liquid to the cavity to facilitate tissue sample ejection from the cavity. The liquid supply unit is disconnected from the cavity of the sample-receiving device when the sample-receiving device is in the first extended position. 
         [0015]    An aspect of the invention provides a biopsy device for harvesting at least one tissue sample from a body of a living being, comprising: a hollow needle with a distal end portion adapted to be introduced into the body; a cutting mechanism for severing the at least one tissue sample; a sample-receiving device with a cavity for receiving the at least one severed tissue sample, the sample-receiving device being receivable in the hollow needle and movable therein between a first extended position and a second retracted position; a transport device for moving the sample-receiving device in the hollow needle; a liquid supply unit adapted to comprise a flushing liquid, the liquid supply unit being operatively connected to the cavity of the sample-receiving device through a hollow liquid transport member so as to allow tissue sample ejection by liquid flushing. 
         [0016]    The liquid supply unit as outlined above allows for cautious handling of the at least one harvested tissue sample during the biopsy procedure and subsequent retrieval of acquired tissue samples to maintain the structural integrity of suspect tissue and allow an accurate diagnosis to be made. Furthermore, individually extracted tissue cores or samples may advantageously be kept apart to enable better diagnostic capabilities. This is beneficial in respect of most kinds of tissue samples, such as prostate samples. In addition, liquid flushing to eject the at least one tissue sample from the cavity of the sample-receiving device allows for automated and rapid biopsy procedures with minimal patient trauma and minimal manual handling of the harvested tissue sample(s) by physicians. 
         [0017]    The flushing liquid is preferably a preserving agent, in which the harvested tissue sample is to be stored following ejection from the cavity of the sample-receiving device. The flushing liquid may e.g. comprise saline or formalin. It will be appreciated that no rough handling of the body tissue sample, e.g. by forceps, is required in order to remove the harvested tissue sample from the cavity of the sample-receiving device, as ejection may be caused solely under the action of the flushing liquid. The cavity may have a substantially circular cross-section. Particularly advantageous embodiments of the biopsy device of the present invention are completely handheld and include integral vacuum supply and liquid supply mechanisms as well as power source, thereby eliminating any need for separate (or external) vacuum, fluid and power sources. Alternatively, the vacuum supply and/or power source could be arranged externally to the biopsy device and connected thereto by suitable electrical power conductors and vacuum hoses. 
         [0018]    In one embodiment, the biopsy device of the present invention comprises a closed system for tissue-sample extraction and transportation to avoid leakage of bodily fluids, operator exposure to biohazards and contamination of extracted tissue samples. This embodiment ensures that manual handling of extracted tissue samples is minimized, and possible handling damage is consequently minimized. 
         [0019]    The hollow needle preferably defines a longitudinally extending annular body portion, which defines a co-extending longitudinal cavity in the hollow needle, and the cavity in the sample-receiving device may have a lateral opening for receiving the at least one tissue sample. 
         [0020]    In one embodiment of the present invention, the cutting mechanism comprises a circumferential cutting edge at the distal end of the hollow needle as described in more detail below. In order to allow efficient tissue severing by the circumferential cutting edge, the sample-receiving device and the hollow needle are preferably movable relative to each other, such that the sample-receiving device may be in a projecting position, in which it projects from a distal tip of the needle, and a retracted position, in which it is accommodated in the hollow needle, and in which the distal end of the device is defined by said circumferential cutting edge and possibly a tapered tip of the sample-receiving device. 
         [0021]    In order to aspirate or suck body tissue into the cavity of the sample-receiving device, the biopsy device of the present invention preferably comprises a vacuum pump for generating a suction effect in the cavity of the sample-receiving device, the vacuum pump being in fluid communication with the cavity of the sample-receiving device through a longitudinally extending passage in the sample-receiving device and/or through the longitudinally extending passage defined by the hollow needle. For example, there may be provided one or more vacuum ports at the bottom of the sample-receiving device, such as in a wall section defining a bottom of the cavity in the sample-receiving device, through which vacuum port(s) the cavity is in fluid communication with the interior of the hollow needle, which in turn is in fluid communication with the vacuum pump. Alternatively, there may be provided one or more vacuum ports in a side wall forming a side portion of the cavity in the sample-receiving device, through which vacuum port(s) the cavity may be in fluid communication with the interior of the hollow needle or with a longitudinally extending passage in the sample-receiving device, the interior of the hollow needle or the passage in the sample-receiving device being in fluid communication with the vacuum pump. Preferably, the vacuum pump is only operated in a short period of time each time a tissue sample is to be harvested, i.e. immediately prior to severing of the tissue sample. Control of the operation of the vacuum pump may e.g. be coupled to control of the cutting mechanism and/or to control of the is transport device, so that the vacuum pump is only activated when the sample-receiving device is in its first extended position or within a predefined period of time after the sample-receiving device has arrived at the first extended position, or within a predefined period of time before the cutting mechanism is activated to sever the tissue sample. Alternatively, control of the vacuum pump may be coupled to control of the cutting mechanism, e.g. such that the vacuum pump is activated when the hollow needle is retracted to lay bare the cavity of the sample-receiving device, cf. the below description of the firing mechanism for severing the tissue sample, and such that operation of the vacuum pump is deactivated when the tissue sample has been severed. 
         [0022]    The at least one tissue sample harvested by the biopsy device of the present invention is preferably harvested in an automatic manner, extracted from the anatomy of the patient, ejected from the sampling-receiving device and individually placed in a suitable tissue storage container in a storing and/or preserving agent. Thus, the operator (or pathologist) is free to concentrate on optimizing tissue sampling and minimizing patient trauma. 
         [0023]    In the biopsy device of the present invention, the liquid supply unit may be operatively connected to the cavity of the sample-receiving device when the sample-receiving device is in its second retracted position, and the liquid supply unit is preferably disconnected from the cavity of the sample-receiving device when the sample-receiving device is in its first extended position. The first extended position is normally the position, in which tissue is collected into the cavity of the sample-receiving device as the cutting mechanism severs the tissue sample, i.e. in the first extended position, in which the sample-receiving device with its cavity are in a distal position. The second retracted position is a proximal position, in which the harvested tissue sample may be ejected from the cavity of the sample-receiving device. 
         [0024]    Preferably, a pump for pumping the liquid from the liquid supply unit to the cavity of the sample-receiving device is integral in the biopsy device. The pump may advantageously comprise a peristaltic pump, which is relative inexpensive. For example, the peristaltic pump may be incorporated in a handle portion of the device. In one embodiment, the peristaltic pump is releasably attached to a handle portion of the biopsy device, so that exchange of the liquid supply unit is facilitated, as the peristaltic pump engages a portion of the hollow liquid transport member (e.g. a plastic or elastomeric hose or tube). In one embodiment, a clamping mechanism is provided, which firmly holds the hollow liquid transport member in abutment with the peristaltic pump, the clamping mechanism preferably being releasable by hand. As an alternative, or in addition to the peristaltic pump, the liquid supply unit may comprise a syringe-like liquid supply chamber and a plunger movably disposed in the liquid supply chamber. Like the pump, the liquid supply unit may be releasably secured to the handle unit, so as to allow for convenient exchange thereof. 
         [0025]    The biopsy device of the present invention may comprise a handle unit, which houses or incorporates a power source, such as a battery pack, and a motor for driving the transport device. The handle unit preferably incorporates no means or elements, which come into physical contact with body tissue, body fluid or the patient&#39;s anatomy during tissue harvesting, so that the handle unit may be re-usable, i.e. usable for several biopsy procedures that each may involve extraction of multiple tissue samples from a patient. The transport device, the hollow needle and the sample-receiving device, which are parts which are likely or inevitably come into contact with body tissue, body fluid or the patient&#39;s anatomy during tissue harvesting, are preferably comprised in a disposable unit, which is releasably secured to the handle unit. The disposable unit is intended to be used for one single biopsy procedure and to be disposed of following harvesting of one or more tissue sample from a harvesting site in the patient anatomy. As described in detail below, multiple tissue samples may be harvested by means of preferred embodiments of the biopsy device without exchanging the disposable unit, once the outer hollow needle of the disposable unit is in place at the harvesting site. 
         [0026]    A flushing chamber may be provided, preferably in the disposable unit, the flushing chamber being adapted for attachment of a sample-collecting container to the biopsy device. Hence, the sample-receiving device is preferably aligned with the flushing chamber in the second retracted position, however other layouts are contemplated, in which the harvested tissue sample is conveyed by means of the flushing liquid from the cavity in the sample-receiving device to flushing chamber and from there to the sample-collecting container. The sample-collecting container may define at least one cavity, and preferably a plurality of cavities for receiving the harvested tissue sample, whereby one or more cavities may communicate with the cavity of the sample-receiving device, when the sample-receiving device is in its second retracted position. The sample-collecting container is preferably releasably mounted to the disposable unit. The at least one cavity for receiving the tissue sample may e.g. comprise a plurality of cavities for receiving individual tissue samples, the sample-collecting container further comprising a movement or rotation mechanism for changing the relative position of the cavities relative to the sample-receiving device, so that different tissue samples harvested at different times can be flushed into separate cavities. For example, the cavities may be circularly disposed on a rotatable disk, rotation of which is controlled by a control system of the biopsy device (or biopsy system) to automatically align a subsequent container cavity with the flushing chamber and/or sample-receiving device, when a body tissue sample has been ejected into a previous container cavity. 
         [0027]    The sample-collecting container, also referred to as the “tissue storage container”, may e.g. have a volume of 10-100 ml, such as 20-30 ml. The liquid supply unit or liquid container may e.g. have a volume of 5-30 ml, such as 5-15 ml, such as approximately 10 ml. 
         [0028]    The flushing chamber may be connected to an outlet valve of the fluid supply unit, which may be pressurized as described. An opening in a wall of the flushing chamber permits liquid to move from the pressurized liquid supply unit into the flushing chamber. On a side of the flushing chamber, opposite the pressurized liquid supply opening, a drain may be provided leading to the tissue storage container, where extracted tissue samples may be individually stored. This drain may be opened and closed by a sliding valve or another suitable closure mechanism. 
         [0029]    The flushing liquid impacts and dislodges a tissue sample held in the cavity of the sample-receiving device, the tissue sample being ejected through the cavity of the sample-receiving device. The flushing liquid subsequently carries the tissue sample through the drain and into the tissue storage container. The flow of flushing liquid into and out of the flushing chamber is controllable by operation of the slidable valve. In one embodiment, the slidable valve is operatively connected to a valve spring which ensures that the valve in its default position closes the opening leading to the pressurized fluid supply as well as the drain leading to the tissue storage container. Alternatively, opening and closing of the valve may be caused by the transport device for moving the sample-receiving device in the hollow needle, the transport device comprising e.g. a bendable elongate element. Thus, a portion of the transport device may interact with the valve or with a means for opening and closing the valve. In general, means may be provided, which prevent that flushing liquid is being drawn into the inner lumen of the hollow needle when vacuum is applied to suck tissue into the cavity of the sample-receiving device. 
         [0030]    When the sample-receiving device is moved towards the second retracted position, the sample-receiving device or the transport device is brought in contact with the slidable valve. The continued retraction of the sample-receiving device causes the slidable valve to be pushed towards the back of the flushing chamber so that the opening leading to the liquid supply unit and the drain leading to the tissue storage container are both opened. This operation permits fluid to enter the flushing chamber, and the sample to move through the drain into the storage container. During this process, the vale spring is energized with potential energy by mechanical compression or with electrical energy. After a tissue sample has been flushed out of the sample-receiving device, it is once again advanced towards the first extended position, whereby the valve is closed, e.g. by electrical energy or by release of potential energy stored in the spring. 
         [0031]    The tissue storage container may be substantially circular and comprise a number of separate identifiable chambers, wherein each chamber is adapted to receive a tissue sample. The storage container may comprise a movable part operatively connected to a suitable driver mechanism in a driver unit, e.g. the handle unit, so as to permit the automatic change of chambers as the biopsy procedure progresses and multiple tissue samples are harvested. Thus, a single tissue sample is preferably captured in each chamber, and the subsequent change of chambers ensures that each tissue sample and its associated storage liquid are confined in the tissue storage container. 
         [0032]    Individual tissue samples may subsequently be identified through their respective placement in the sample-receiving device, and individual chambers may furthermore be named, coded or otherwise made recognizable/identifiable. A counter may be included to assist the operator in keeping track of the number of biopsies taken. In order to further automate the biopsy procedure several of all of the chambers of the tissue storage container may be partially pre-filled with a preserving agent such as concentrated formalin or another suitable preserving agent. In this way, the flushing liquid injected into the flushing chamber serves at least two purposes, (1) to carry the tissue sample from the sample-receiving device into the storage container, and (2) to adjust the concentration of the preserving agent in the storage container to a level suitable for the preservation of tissue samples. 
         [0033]    In order to facilitate tissue penetration of the sample-receiving device, the sample receiving device may comprise or be formed as a cannula with a sharpened distal tip. The cannula extends coaxially with the hollow needle in the hollow needle. 
         [0034]    It will be appreciated that the handle unit preferably is embodied as a hand held unit, which accommodates all required power, liquid and vacuum sources as well as possible driving mechanisms for needle and sample-receiving device and firing mechanisms, cf. below. Generally, the entire biopsy device of the present invention, including the hollow needle, the cutting mechanism, the sample-receiving device, the transport device, the liquid supply unit and all other structural elements mentioned herein may be comprised in a hand-held unit. 
         [0035]    One alternative embodiment of the vacuum-flush mechanism previously described employs twin syringe-plunger systems as an alternative to a syringe-plunger system and a vacuum-working fan. The present vacuum-flush mechanism comprises of twin syringe chambers, each with a plunger slidably disposed in the inner cavity of each chamber. 
         [0036]    A first chamber functions as a vacuum supply unit and comprises two openings, each fitted with a one-way valve. One valve permits air to enter an inner cavity of the chamber when the plunger pertaining to this chamber is retracted. This valve is in fluid communication with the proximal end of the cutting cannula. When the plunger is retracted, air is drawn out of the inner lumen of the hollow needle and a vacuum is created. This vacuum is communicated through the inner lumen of the hollow needle and into the inner cavity or tissue cavity of the sample-receiving device where it engages and aspirates tissue through the lateral opening of the sample-receiving device and into the inner cavity of the container. Another valve permits air to escape when the plunger is moved forward. 
         [0037]    The vacuum supply plunger may be powered by a rack-and-pinion system or another coupling mechanism housed in the handle unit. 
         [0038]    Another unit comprises a pressurized liquid supply unit. It comprises of a syringe-like chamber and a plunger movably disposed inside said chamber, and has two openings, each fitted with a one-way valve. One valve permits the flushing fluid such as saline, water etc. to enter the cavity defined by the chamber when the plunger pertaining to this chamber is retracted. This valve is connected to a liquid supply with a tight connection. The liquid supply may comprise a plastic container with relatively soft walls, so that in response to retraction of the plunger, flushing liquid is drawn from the liquid supply unit and into the inner cavity of the chamber. The walls of the plastic container collapse inward as the container empties, ensuring that no air gets into the system. By subsequent forward movement of the plunger, the flushing liquid is ejected from the inner cavity of the chamber and through the outlet valve into a flush-out chamber. 
         [0039]    The pressurized liquid supply plunger is operatively connected to the driver unit and backward motion may be provided by a suitable power-transmitting component or coupling means mounted for example on the shaft of the plunger. The forward motion of the plunger is preferably powered by a spring that is operatively connected to the shaft of the plunger. When the shaft of the plunger is moved backwards, potential energy is stored in the spring. At a given point, the shaft is released, and the potential energy stored in the spring is released to move the plunger forward and eject the flushing liquid from the chamber. At the end of the biopsy cycle, the plunger shaft is once again engaged by the power-transmitting mechanism, and a new cycle may be initiated. 
         [0040]    The transport device (or transport mechanism) may be coupled with the cutting mechanism and a compact driver system featuring all necessary controls and mechanics. The vacuum supply unit may either be integrated with the handle unit or it may be arranged in an external or freestanding unit. The transport mechanism preferably enables the collection and removal of multiple tissue samples in a fast, efficient and reliable procedure. The cutting mechanism preferably enables the instant and efficient severing of tissue samples. This may be accomplished with rotating cutters of spring-loaded mechanisms, although electro-cautery is also applicable. The handle unit comprises drivers that deliver the necessary actuation forces and motions to the transport and cutting mechanisms. This may e.g. be accomplished through several means, the most common being springs, electric motors or air-powered drives. 
         [0041]    The transport device of the present biopsy device may include any suitable system for moving the sample-receiving device in the hollow needle, i.e. any system capable of pulling the sample-receiving device from the first extended position to the second retracted position and of pushing the sample-receiving device from the second retracted position to the first extended position. For example, the sample-receiving device may be mounted on or connected to a rigid, longitudinally extending element such as a metallic cannula coaxially arranged inside the hollow needle. The rigid element may be forwardly and backwardly movable, e.g. by a linear actuator or by a motor-driven friction wheel or gearwheel engaging the rigid element. Thus, the rigid element may e.g. comprise a toothed rack engaged by a motor-driven gearwheel. 
         [0042]    In one presently preferred embodiment, the transport device for moving the sample-receiving device in the hollow needle comprises a bendable elongate element, such as a steel wire, two or more twisted wires, such as a Bowden cable or any other flexible or bendable element. The elongate element is preferably bendable away from the longitudinal direction of the hollow needle, i.e. laterally bendable, and it preferably has sufficient stiffness or sufficient support in lateral directions to prevent the bendable elongate element from flexing outwardly when the sample-receiving device is to be pushed from the second retracted position to the first extended position. 
         [0043]    Preferably, a coiling device is provided for coiling up the bendable elongate element, the coiling device being preferably arranged at a proximal end of the device, such as at least proximal of the second retracted position. In embodiments, in which the bendable elongate element is comprised in a disposable unit, which is attachable to e.g. a handle-unit or a stationary unit of the biopsy device, the coiling device is preferably integrated in the disposable unit as elaborated in more detail below. 
         [0044]    The bendable elongate element may have a longitudinally extending portion of circular or non-circular cross section, such as e.g. polygonal cross-section, such as triangular or rectangular. A polygonal cross-section confers the possibility that the bendable elongate element may be toothed for engagement by a driving gearwheel. Thus, in one embodiment, the bendable elongate element comprises a row of regularly spaced teeth extending substantially perpendicularly to a longitudinal axis of the elongate element. In this embodiment, the biopsy device may have a rotatable gear wheel having a rim with teeth for interacting with the teeth of the elongate element so as to move the elongate element in the hollow needle along the longitudinal axis. One or more supports may be provided for supporting the bendable elongate element in the lateral direction to avoid flexing thereof, the support(s) comprising e.g. two opposing wall sections arranged with a mutual clearance corresponding to a thickness of the bendable elongate element, the bendable elongate element being free to slide in the longitudinal direction between the wall sections. Similarly, the bendable elongate element may slide between opposing roller elements. 
         [0045]    In order to allow the sample-receiving device to rotate relative to the bendable elongate element, the sample-receiving device may be secured or attached to the bendable elongate element by means of a swivel joint. 
         [0046]    From the above discussion, it will be appreciated that the sample receiving device may have a length, which is substantially shorter than a length of the hollow needle, and that a distal end of the bendable elongate element may be attached to a proximal end of the sample-receiving device, so that the bendable elongate element causes movement of the sample-receiving device in the hollow needle. 
         [0047]    It will also be understood that the biopsy device of the present invention may comprise a handle unit with a power source and a motor for driving the transport device, and that the transport device, the hollow needle and the sample-receiving device may be comprised in a disposable unit, which is releasably secured to the handle unit. A driving interface is preferably provided to transmit a driving force from the motor in the handle unit to the bendable elongate element in the disposable unit. 
         [0048]    The coiling device is likely to be contaminated by body tissue and/or body fluids during tissue sample harvesting, as the bendable elongate moves in the hollow needle, the inner wall of which may be in contact with the tissue sample, when the tissue sample is being moved in the cavity of the sample-receiving device. Thus, the coiling device is preferably comprised in the disposable unit. Irrespective of whether the coiling device is comprised in the disposable unit or in other parts of the biopsy device, such as in the handle unit, the coiling device may form a spiral. The spiral may e.g. be formed by at least one wall element, which is arranged such that contact between coiled-up portions of the bendable elongate element is prevented to avoid uncontrolled bending or varying dimensions of a coiled bendable elongate element. 
         [0049]    Embodiments of the biopsy device of the present invention, which form a handheld unit, preferably also include the transport device, e.g. the bendable elongate element, in the handheld unit. 
         [0050]    Further embodiments and features will become apparent from the below description. 
         [0051]    Transfer of samples from the point or position of sampling (or harvesting site) to the point or position of collection (or sample ejection) is preferably carried out by means of a flat, toothed bar, preferably of a polymer material such as polypropylene, to which the sample-receiving device is attached, the sample-receiving device being e.g. in the form of a canoe-like container to hold tissue samples once they have been severed. The sample-receiving device may have a side-facing opening for receiving tissue samples, and may have one or several vacuum ports to enable the aspiration of tissue into the sample-receiving device by application of vacuum. Severing of tissue samples may be carried out by means of a coaxial, piston-like system comprising a spring-loaded outer cutting cannula (i.e. the hollow needle) with a sharpened distal end (i.e. the circumferential cutting edge) and capable of axial movement, and an inner guiding cannula with a sharpened tip capable of penetrating tissue as the biopsy device is positioned in the tissue to be sampled. The inner guiding cannula may be non-movable or movable by the transport device described herein. The inner cannula may have a side-facing notch (or cavity) enabling tissue to prolapse into the inner lumen of the cannula and into the waiting sample-receiving device. The transport system for the sample-receiving device and/or for the severed tissue sample is axially movable within the inner lumen of the inner cannula, e.g. to advance and retract the sample-receiving device. Power for driving the transport mechanism may be delivered by an electric or pneumatic driver unit. Expelling of samples from the sample-receiving device and into a suitable transport container may be done by means of liquid or pressurized air at the point of collection (or ejection). 
         [0052]    The bendable elongate element may comprise a flat bar, toothed on one side, and it may be made from a suitable polymer material such as polypropylene or Nylon™. The bendable elongate element is moved longitudinally in the cannula system and enables the transport of tissue samples from the harvesting site at the distal tip of the biopsy device, e.g. the first extended position of the sample-receiving device, to the point of ejection, e.g. the second retracted position of the sample-receiving device. It may fit tightly to the wall of the inner cannula to ensure lateral stiffness once it enters the cannula. A cavity on the upper side may enable the application of vacuum to the distal end of the system. The distal point of the cannula system may feature an attachment device to enable the temporary coupling of the cannula with the suspect tissue mass, e.g. a tumor. 
         [0053]    The bendable elongate element (or bar) may be coupled with a sample-receiving device with a vacuum gate. This vacuum gate may have several different configurations, depending on the application and the design of the expelling (i.e. flushing) chamber. The flat toothed bar may establish a vacuum channel in the cannula. The sample-receiving device may receive the tissue during the sampling procedure and hold the sampled tissue on its way from the point of sampling or harvesting to the point of collection. A filter or grid may be provided to ensure that no tissue escapes the container. 
         [0054]    A coupling mechanism between the toothed bar and the sample-receiving device may permit a swiveling motion of the sample-receiving device relative to the flat bar as the sample-receiving device is readied for emptying (or ejection), to facilitate the emptying procedure. 
         [0055]    The toothed bar may interact with a pinion, allowing the conversion of rotational motion of the pinion to linear motion of the toothed bar to enable the withdrawal of harvested tissue samples and the positioning of the sample-receiving device in the cannula system, i.e. in the outer hollow needle. The pinion may be of metal or a ceramic material to ensure longevity. 
         [0056]    The motor for driving the sample receiving device or pinion may be an electric motor. Two batteries and a switch (on/off switch) may be provided for activating and driving the motor. The motor may be pneumatic, which may render the system MRI-compatible. 
         [0057]    The coiling device may comprise a spool-like component placed in the handle to enable the coiling-up of the toothed bar as it is retracted. Hereby the toothed bar will not protrude far beyond the proximal end of the transport mechanism. This is an advantage, in particular when taking biopsies at deep anatomical depths. Alternatively, the toothed bar can be bent away from its longitudinal direction. 
         [0058]    A guiding wheel may be incorporated to stabilize the flat bar and the sample-receiving device as the assembly is advanced into the cannula system. 
         [0059]    A driver unit of the biopsy device may comprise the following components: One or more motors integrated in a suitably designed handle. The motor may generally have two main functions, namely to advance and retract the flat, toothed bar with the sample-receiving device, and to cock and release the firing mechanism when a sample has been readied for cutting. The cocking of the cutting mechanism may result automatically once the system is put into operation, with the retraction, emptying and extension of the sample-receiving device automatically following the firing of the cutting mechanism. Control of the device may result e.g. from the depressing of a pedal or a selection of buttons. The driver unit may be either electrically or pneumatically driven, and it is preferably an independent, completely freestanding unit with its own power supply, vacuum-source and tissue collection container. It may be configured to enable (by selection) one or more of the following operation modes: stepwise, semi-automatic or fully automatic. 
         [0060]    The vacuum supply and the expelling mechanism may either be integrated parts of a handle housing the driver unit, or they may be placed in an external unit. The expelling mechanism (or ejection system) may utilize air pressure, water flushing or a third means of expelling the tissue. 
         [0061]    As an alternative to the toothed bar, a wire, e.g. a steel wire, may be used as a transport mechanism. The steel wire can be a single wire, or it can have two or more twisted wires, with or without a core wire, a principle known from the so-called Bowden cables. The Bowden cable may be coiled up as described above. To enable the functioning of such a wire, the spool used to coil up the wire may have a groove in its surface tailored to the dimensions of the wire, and the spool may be suspended in a tight-fitting housing unit, whereby a channel is formed for the wire. The use of a stiff wire, in combination with the tailored channel, enables the retraction and advancement of the sample-receiving device within the guiding cannula. 
         [0062]    In a default position of the biopsy device, the flat bar with the sample-receiving device may be maximally extended, and the sample-receiving device may be placed in the distal end of the cutting system. The outer cannula may be maximally extended, covering the tissue-receiving port in the inner cannula as the system is advanced into the body of the patient. 
         [0063]    When a sampling sequence is initiated, the driver unit may be activated to start cocking of a spring-loaded firing mechanism as described in more detail below, and the outer cannula may be pulled towards the proximal end of the device, opening the tissue-receiving port. Once the outer cannula has been retracted to open the tissue receiving port, a vacuum may be applied to the inner lumen of the inner cannula, sucking tissue into the tissue receiving port and into the sample-receiving device. 
         [0064]    After the cutting mechanism has been retracted, the sample taking mechanism may release the spring-loaded firing mechanism, rapidly advancing the outer cannula to sever the tissue sample. Upon severing of the tissue sample, the flat, toothed bar with the sample-receiving device may be retracted and carry the biopsy sample towards the point of collection (or ejection). 
         [0065]    A mechanism at the proximal end of the inner cannula may engage and swivel the sample-receiving device when it exits the inner cannula to facilitate the expelling (or ejection) of samples. As the sample-receiving device enters the expelling chamber, a stream of liquid may automatically be released to flush the tissue sample out of the sample-receiving device and into a suitable container. The flushing liquid is preferably saline, possibly containing additives for preserving the sample or preparing it for examination. 
         [0066]    Having completed the expelling cycle, the flat, toothed bar and the sample-receiving device are advanced, and the sample-receiving device may be positioned in the distal end of the inner cannula in preparation of a new cycle. On the completion of the sampling sequence, the outer cannula may be left in the default position to close the tissue receiving port in preparation of the removal of the biopsy needle. The tissue storage container may be detached from the biopsy device and sent to the pathologist for further analysis. 
         [0067]    A tip of the sample-receiving device may be conical, and it may be configured to serve as a penetration point, tissue-receiving port, sample container and a cutting board. 
         [0068]    In the present invention, the outer diameters of biopsy needles may be within the range from 0.5 mm to 5.0 mm, such as in the range from 1.2 mm to 3.0 mm Biopsy needles are typically made of stainless steel, but other materials can be used such as titanium, which is MRI compatible. 
         [0069]    In order to accurately control movement of the sample-receiving device in the hollow needle, the sample-receiving device and the hollow needle may be shaped, so that relative rotational displacement between the sample-receiving device and the hollow needle in said plane is prevented. For example, the outer cutting cannula or hollow needle may comprise first orientation means adapted to co-operate with mating second orientation means of the sample-receiving device, so as to guide and orient the sample-receiving device in a plane substantially perpendicular to the axis of movement of the sample-receiving device inside the outer cutting cannula. The orientation means may ensure reliable positioning of a sample ejection aperture of the sample-receiving device in a plane substantially perpendicular to the axis of movement thereof, so as to support automated ejection of extracted tissue samples. For example, the oval cutting cannula and the sample-receiving device may have oval profiles, or an inward protuberance may be provided on an inner wall of the cutting cannula (outer needle), the protuberance engaging a corresponding groove in the sample-receiving device. 
         [0070]    The biopsy device of the present invention may further comprise a first user-operable firing mechanism for causing the hollow needle and the sample-receiving device to be longitudinally displaced in a distal direction, so as to penetrate body tissue at or near the suspect tissue mass; and a second user-operable firing mechanism for causing the hollow needle to be longitudinally displaced in a distal direction from a first position, in which the sample-receiving device projects from the distal end of the hollow needle, to a second position, in which the hollow needle essentially accommodates the cavity of the sample-receiving device, so as to sever said tissue sample from remaining body tissue at the harvesting site. 
         [0071]    It should be understood that the first user-operable firing mechanism is optional, i.e. the biopsy device may include only the second firing mechanism. The first firing mechanism may advantageously be incorporated in a separate module, which may or may not be mounted to the device during assembling thereof. 
         [0072]    The first firing mechanism is useful for penetrating a suspect tissue mass, e.g. a tumor, penetration of which may be difficult due to e.g. hardness or due to a loosely supported attachment of the suspect tissue mass to surrounding tissue of the body. The loosely supported attachment may cause the suspect tissue mass to displace by pressure from the tip of the biopsy needle and to slide past the suspect tissue mass without penetrating it. It has been found that, by firing the inner and outer needles substantially simultaneously, preferably at a relatively high speed, it is possible to contact and penetrate even a loosely supported tissue mass. Below, the substantially simultaneous firing of the outer needle and the sample-receiving device will be referred to as a “double shot”. 
         [0073]    The biopsy device may comprise a control system for the first and second user-operable firing mechanisms, the control system being configured such that only one of the firing mechanisms can be activated at a time. The control system may be based on electronic control means, which provide a control signal to one or more motor(s) and other elements of the firing mechanisms. In order to expedite tissue harvesting, the control system may be configured to automatically activate the second firing mechanism after firing of the first firing mechanism, i.e. so that a tissue sample is automatically severed upon penetration of the suspect tissue mass. 
         [0074]    The first and second firing mechanism may comprise respective energy storage and release mechanisms. The energy to be stored may e.g. be provided by an electrically driven motor. The energy release mechanisms may be controlled to substantially instantaneously release the stored energy to fire the outer hollow needle and the sample-receiving device substantially simultaneously (double shot, first firing mechanism) or to fire the outer hollow needle solely (“single shot”, second firing mechanism). The energy storage means may e.g. comprise springs, such as compression springs. Thus, the first firing mechanism may comprise a first compression spring, and the second firing mechanism may comprise a second compression spring, and the device may further comprise at least one loading mechanism for loading the first and second springs and for releasing the springs upon loading thereof. The loading mechanism may comprise one or more elements for transmitting a displacement of one or more actuators to the springs. The actuator(s) may e.g. comprise at least one linear actuator and/or at least motor, the rotational motion of which may be converted into linear displacement of one or both compression springs. Such conversion of motion may e.g. be provided via a gear/rack drive, or via abutment of a member protruding from a surface of a rotational wheel with a linearly displaceable member. For most applications, the force provided by each of the first and second springs may be 20-150 N, such as 40-80 N, such as approximately 50 N. 
         [0075]    The first firing mechanism may be connected to a needle driving member, which is secured to the hollow needle to transmit the firing force of the first spring or other energy storage means to the hollow needle. The first and second firing mechanisms, the hollow needle, the sample-receiving device and the needle driving member are preferably comprised in a disposable unit, which is releasably attached to the handle unit. The first spring is preferably connectable to the transport device for moving the sample-receiving device in the hollow needle, and the first spring may further be connected to the needle-driving element. Thereby, the hollow needle and the sample-receiving device may be longitudinally displaced upon release of the first firing mechanism. 
         [0076]    A first power-driven element, e.g. a motor, may be provided for driving the transport device to move the sample-receiving unit backward and forward in the hollow needle. In order to minimize resistance to the firing force provided by the first firing mechanism, the loading mechanism may be configured to, upon loading of the first spring, decouple the transport device from the motor, the transport device being preferably movable along with the sample-receiving device in the hollow needle at firing of the first firing mechanism. In one embodiment, motion of the motor is transmitted to the transport device, comprising e.g. a bendable elongate element, via a gear drive. That gearwheel of the gear drive, which engages the transport device, may be left in engagement with the transport device for stabilization thereof during firing of the first firing mechanism. Thus, decoupling of the transport device from the motor may be performed at a location, which is closer to the motor in the transmission chain than the actual location of engagement between the gear drive and the transport device. The aforementioned stabilization is particularly useful in embodiments, in which the transport device comprises a bendable elongate element. 
         [0077]    The first and second firing mechanisms may comprise a common trigger element and a second power-driven element for moving the trigger element. The trigger element may e.g. comprise a linearly displaceable member or a rotational member, such as a gearwheel. The control system of the biopsy device may be configured such that the first firing mechanism can be loaded and fired during a first movement segment of the trigger element, and so that the second firing mechanism can be loaded and fired during a second movement segment of the trigger element. For example, if the trigger element comprises a linearly displaceable member having a certain stroke, the first movement segment may correspond to a part of the stroke, and the second movement segment may correspond to a second part of the stroke. Alternatively, if the trigger element comprises a rotational element, the first movement segment may correspond to rotation of an initial angle of e.g. 90°, and the second movement segment may correspond to rotation of a subsequent rotation of e.g. another 90°. 
         [0078]    The transport device and the first and second firing mechanisms may conveniently be powered or driven by one single motor such an electrical motor or pneumatic motor. It will thus be appreciated that first and second movement segments of the motor may be for loading the first and second firing mechanisms, respectively, whereas a further movement segment, e.g. rotation of another 170° of the trigger element, may be for movement of the sample-receiving device between the first extended position and the second retracted position. 
         [0079]    It will thus be appreciated that the trigger element may be arranged with respect to the firing mechanisms and the transport device such that movement thereof in a first direction causes firing of at least one of the first and second firing mechanisms, and such that further movement of the trigger element in the first direction causes movement of the transport device to move the sample-receiving device from the first extended position to the second retracted position for ejection of a harvested tissue sample. This may e.g. happen during rotation of at most 360° of the trigger element, cf. the above example of angular ranges, which accumulate to 350°. Movement or rotation of the trigger element in a second direction, e.g. opposite rotation of opposite linear displacement, may cause movement of the transport device to move the sample-receiving device from the second retracted position to the first extended position for harvesting of a further tissue sample and/or for firing of a further double shot. The movement of the trigger element in the second direction may cause resetting of the first and/or second firing mechanisms to reset the mechanism(s) for a subsequent cycle of double and or single shots. 
         [0080]    The control system of the biopsy device may comprise an electrically activated solenoid for causing an impart member of the first firing mechanism to move into a path of movement of the trigger element. For example, the trigger element may comprise a rotational wheel having an outwardly protruding element projecting from a surface thereof. When the solenoid has not caused the impart member of the first firing mechanism to move into the path of movement of the trigger element, the protruding element moves past the first firing mechanism without activating it during movement of the trigger element. Thus, only the second firing mechanism will be activated. If the solenoid is activated, however, the outwardly protruding element engages the impart member of the first firing mechanism, and movement of the trigger element will load and fire the first firing mechanism, before the second firing mechanism is possibly loaded and fired. It should be understood that the solenoid may, alternatively, be arranged to move the trigger element, so that its path of movement coincides with the impart member of the first firing mechanism. 
         [0081]    In case the biopsy device is embodied as a hand-held unit, the first and second firing mechanisms may advantageously form part of the hand-held unit. 
         [0082]    In one embodiment, the control system of the biopsy device is configured to operate the firing mechanisms and the transport device in a predefined cycle. Such a cycle may e.g. comprise the steps of: optionally performing a double shot, if an operator of the device has initiated the double shot by providing a corresponding input to the control system, e.g. via an interface in the handle unit; activating a vacuum pump optionally included in the device to aspirate or sever tissue into the cavity of the sample-receiving device; performing a single shot to sever the tissue sample and interrupting vacuum suction prior to or subsequent to severing; moving the sample-receiving device to the second retracted position; ejecting the tissue sample from the sample-receiving device, e.g. by liquid flushing as described below; and returning the sample-receiving device to the first extended position. 
         [0083]    The control system may e.g. be programmable or pre-programmed to perform other cycles, e.g. multiple repetition the steps of: performing the single shot; moving the sample-receiving device to the second retracted position; ejecting the tissue sample from the sample-receiving device; and returning the sample-receiving device to the first extended position, so as to harvest a plurality of tissue samples without user intervention between the individual severing (i.e. single shot) operations. 
         [0084]    The biopsy device may further comprise a control system for controlling movement of the transport device and for arresting the sample-receiving device in the second retracted position. The second retracted position is normally that position of the sample-receiving device, in which the at least one severed tissue sample may be ejected from the cavity of the sample-receiving device. In order to take the burden of arresting the sample-receiving device in the correct position off the physician operating the device, the aforementioned control system may thus be configured to automatically arrest the sample-receiving device in the second retracted position. In one embodiment, the control system comprises a sensor for detecting the position of the sample-receiving device and/or the cavity therein. For example, a photocell or an electromechanical switch may be provided for providing a signal to the control system, when the sample-receiving device is in or close to its second retracted position. Alternatively, or in addition, the control system may be arranged to automatically detect a distance between the first extended position and the second retracted position. 
         [0085]    It will thus be appreciated that the control system may allow the biopsy device to automatically operate with different needles of different lengths, there being no need for configuration by the user of the device in order to adapt the control system to a specific needle length. In case the hollow needle and the sample-receiving device are comprised in a disposable unit, which is releasably attached to the handle unit of the device, exchange of the hollow needle with another one of different length is easily performed. Such exchange is further facilitated thanks to the ability of the control system to arrest the sample-receiving device in the second retracted position without specific user input being required for adapting the control system to a specific needle length, and the biopsy device is further rendered fail-safe with respect to correct positioning of the sample-receiving device in the second retracted position. 
         [0086]    The control system may for example be configured to automatically detect a distance between the first extended position and the second retracted position of the sample-receiving device upon attachment of the disposable unit to the handle unit. Accordingly, the control system may be configured to detect placement or replacement of the disposable unit in the handle unit, e.g. by means of a sensor integrated in the handle unit, and, in response to such detection, initiate the aforementioned detection of the distance between the two positions. 
         [0087]    In order to achieve the detection, the disposable unit may comprise an electronic memory, and the handle unit may comprise an electronic interface for deriving information stored in the electronic memory, the electronic interface being configured to communicate the information to the control system. It should be understood that the ability of communicating between a disposable unit and further elements of the biopsy device, e.g. the handle unit, constitutes and independent aspect of the present invention, which may benefit from, but which does not require the presence of other features disclosed herein. For example, the unit accommodating the control system may be a hand-held or non-hand unit. The electronic memory may e.g. comprise a three or four terminal serial EEPROM, EPROM or ROM containing terminals ground, Vdd, CLK and bidirectional data line, such as a serial EEPROM ATMEL AT24C01. The information stored in the electronic memory may e.g. represent a distance between the first extended and the second retracted position of the sample-receiving device, a length of the outer hollow needle and/or a length of the bendable elongate element. 
         [0088]    As an alternative or supplement to the electronic memory, the control system may comprise a sensor for detecting when the sample-receiving device reaches a proximal extremity of its movement range, the movement range being preferably predefined. The proximal extremity may for example be the second retracted position or a position at a predefined distance from the second retracted position, which predefined distance is independent of the length of the needle, i.e. which does not change when the disposable unit is exchanged. A distal extremity of the sample-receiving device may e.g. be the first extended position. The sensor for detecting the arrival of the sample-receiving device at the proximal extremity may e.g. detect a change in a physical characteristic, for example the change of electrical current or voltage, magnetic field, or the change of an acoustic, optical or mechanical parameter. The sensor may comprise a Hall sensor, potentiometer, current measuring device or a mechanical switch. 
         [0089]    For example, the transport device may comprise a position or movement signal generator for generating a position or movement signal to the control system indicative of the longitudinal position or movement of the sample-receiving device. In this embodiment, the control system is configured to, upon mounting of the hollow needle and the sample-receiving device to the handle unit: activate the transport device to retract the sample-receiving device to its proximal extremity and to record the position or movement signal in the proximal extremity; and to utilize the recorded position signal as a position reference point for subsequent arresting of the sample-receiving device in the second retracted position following tissue harvesting. 
         [0090]    Preferably, a driving force is transmitted to the transport device from a motor, which is controlled by a microcontroller, the microcontroller receiving the position or movement signal as an input, in dependency of which input an output for the motor is generated. 
         [0091]    To achieve the desired position control of the sample-receiving device, the control system may comprise at least one pulse-emitting device, such as a Hall element, for producing pulses in dependency of the movement or position of the sample-receiving device. The proximal extremity of the sample-receiving device may be defined by a mechanical stop for the sample-receiving device, conferring a change in the production of pulses when the sample-receiving device makes contact with the mechanical stop. 
         [0092]    In case the transport device receives a driving force from an electrically driven motor, the sensor may, as an alternative or supplement to the Hall element, comprise a current or voltage sensor for measuring motor current passing through the motor. Accordingly, a rise of motor current beyond a predefined threshold value may be used as an indicator that the sample-receiving device has reached its proximal extremity, e.g. a mechanical stop. 
         [0093]    The aforementioned position signal generator may comprise a potentiometer, the potentiometer being e.g. arranged at a transmission axle for transmitting a driving force to the transport device. 
         [0094]    Upon mounting of the disposable unit to the handle unit, the control system may perform an initial run or calibration cycle to move the sample-receiving device to its distal and/or proximal extremity to determine the length of the needle, the distance between the first extended and the second retracted position of the sample-receiving device or any other value, which may render the control system capable of arresting the sample-receiving device in the second retracted position. The initial run preferably returns the sample-receiving device to a default position, e.g. the first extended position. 
         [0095]    The handle unit, the hollow needle, the sample-receiving device, the transport device and the control system and optionally all other components of the present biopsy device may be comprised in a hand-held unit. 
         [0096]    In an independent aspect, the present invention provides a method of harvesting at least one biopsy tissue sample from a body of a living being, the method comprising the steps of: introducing a hollow needle with a distal end portion into the body; severing the at least one tissue sample, so as to collect said at least one tissue sample in a sample-receiving device with a cavity for the severed tissue sample; moving the sample-receiving device in the hollow needle from a first extended position to a second retracted position; and ejecting the at least one tissue sample from the cavity of the sample-receiving device by flushing a liquid through the cavity. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0097]    An embodiment of the invention will now be described with reference to the drawings, in which: 
           [0098]      FIG. 1  is a general illustration of a biopsy device; 
           [0099]      FIG. 2  is an exploded view of an embodiment of the biopsy device; 
           [0100]      FIGS. 3-6  illustrate a liquid flushing system in the biopsy device; 
           [0101]      FIGS. 7-25  illustrate a first firing mechanism for firing an outer needle and a sample receiving device of a biopsy device essentially simultaneously; 
           [0102]      FIG. 26  illustrates a locking mechanism for a gearwheel of the firing mechanisms; 
           [0103]      FIGS. 27-31  illustrate a second firing mechanism for firing only the outer needle; 
           [0104]      FIGS. 32-35  illustrate a mechanism for moving the sample-receiving device in the outer needle; 
           [0105]      FIG. 36  is an exploded view of a gear chassis of the biopsy device; 
           [0106]      FIGS. 37 and 38  illustrate cycles of a trigger wheel of the first and second firing mechanisms; 
           [0107]      FIGS. 39 and 40  illustrate an embodiment of a system for determining a distance between two positions of the sample-receiving device. 
       
    
    
       [0108]    While the invention is susceptible to various modifications and alternative forms, specific embodiments are shown by way of example in the drawings and are described in detail herein. It should be understood however, that the invention in not intended to be limited to the particular forms disclosed. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0109]      FIG. 1  shows a simplified schematic illustration of a biopsy device incorporating features of the present invention. The device includes biopsy needle  108  comprising a hollow needle  50 , in which there is arranged a longitudinally movable tissue sample-receiving device  52 . The sample-receiving device comprises a tapered distal tip  54  and a cavity or canoe  56  for receiving a tissue sample. The sample-receiving device comprises a vacuum port  58 , which is in fluid communication with the canoe  56  to allow tissue to be sucked into the canoe once the canoe is placed at a suspect site within the body of a living being. Vacuum is provided by a vacuum pump (not shown). A distal end portion of the hollow needle  50  provides a circumferential cutting edge  60  for severing the tissue sample sucked into the canoe  56 . The device comprises a spring-loaded firing mechanism, which in  FIG. 1  is schematically illustrated by a spiral spring  62 , the firing mechanism being arranged to displace the hollow needle  50  in a forward (distal) direction to sever the tissue sample sucked into the canoe  56 . At a proximal end of the device, there is provided a sample flushing chamber  109 , from which the severed tissue sample in the canoe  56  can be ejected into a sample container  64 . More specifically, the sample-receiving device  52  with the canoe  56  is retracted from a first extended position, in which the canoe  56  projects from the distal end of the hollow needle  50  as shown in  FIG. 1 , to a second retracted position, in which the canoe  56  is aligned with upper and lower openings in the sample flushing chamber  109 . A flushing liquid, such as saline, is applied to eject the tissue sample from the canoe  56  into the sample container  64 , the flushing liquid being conveyed from a liquid container  114  via a hollow liquid transport member or tube  116  by the aid of a peristaltic pump  118 . 
         [0110]    In order to move the sample-receiving device  52  with the canoe  56  between the first extended position shown in  FIG. 1  and the second extracted position, there is provided a transport device comprising a bendable elongate element  66  in the form of a bendable bar or wire. A lower surface of the bendable bar or wire is toothed, so that it may engage a rotatable gear wheel or pinion  68  arranged to longitudinally displace the bar or wire  66  to thereby move the sample-receiving device  52  backward and forward in the hollow needle  50 . A motor  70  is provided to impart a driving force on the gear wheel or pinion  68 , and a guiding wheel  72  is provided to stabilize the bendable, flexible bar or wire  66 . In order to control the bar or wire  66  when the canoe  56  is retracted for tissue sample ejection, there is provided a coiling device  74  for the bar or wire  66 . 
         [0111]    The biopsy device schematically illustrated in  FIG. 1  is operated as follows: Initially, the sample-receiving device  52  and the hollow needle  50  are arranged, such that the sample receiving cavity or canoe  56  is covered by the hollow needle  50 , i.e. such that the outer surface of the tapered distal tip  54  of the sample-receiving device  52  forms a tapered distal continuation of the outer surface of the hollow needle  50 . In this configuration, the needle  108  is caused to penetrate body tissue of a patient, for example through manual insertion into the patient&#39;s body by a physician. Once the needle has penetrated a suspect tissue mass, e.g. a tumor, the hollow needle  50  is retracted to the position shown in  FIG. 1 , thereby compressing the spring  62  and thus loading the firing mechanism for the hollow needle. Vacuum is then applied through vacuum port  58  to suck tissue into the canoe  56 . The firing mechanism for the hollow needle  50  is subsequently released, and the hollow needle  50  is fired forwardly, i.e. in a distal direction, to its initial position, in which it covers the canoe  56 . This forward firing brings about the result that the circumferential cutting edge  60  of the hollow needle severs the tissue sample in the canoe  56 . The sample-receiving device  52  is then retracted to its second retracted position, in which the canoe  56  is aligned with the sample flushing chamber. Movement of the sample-receiving device is caused by rotating the gear wheel  68  in a clockwise direction, the gear wheel  68  engaging the flexible bar or wire  66 , which in turn is attached to the sample-receiving device  52 . In the retracted position of the canoe  56 , a flow of flushing liquid is forced to pass through the sample flushing chamber to eject the tissue sample from the canoe into the sample container  64 . Once ejection has been completed, the flow of flushing liquid is interrupted, and the gear wheel  68  is rotated counter clockwise to cause the flexible bar or wire  66  to be displaced in a distal direction, whereby the sample-receiving device  52  is pushed back to its first extended position. The above described cycle including tissue sample harvesting and ejection may then be repeated one or more times to obtain several tissue samples without retracting the hollow outer needle  50  from the suspect site in the body. 
         [0112]    It should be understood that the elements provided at the proximal end of the biopsy device shown in  FIG. 1 , i.e. the firing mechanism including spring  62 , gear wheel or pinion  68 , motor  70 , guiding wheel  72 , coiling device  74 , optionally the sample container  64 , sample flushing chamber  109 , liquid container  114 , tube  116 , pump  118 , and vacuum pump (not shown) may be conveniently integrated in a handle unit as elaborated in the below-appended description of embodiments of the invention. 
         [0113]      FIG. 2  is an exploded view of an embodiment of a biopsy device according to the present invention. The device comprises a left cover part  100  and a right cover part  102  and, interposed between the cover parts, a gear chassis unit  104  and a disposable unit  106  including a biopsy needle  108  and a sample flushing chamber  109 . There is further provided a first firing mechanism  110  for firing the biopsy needle in a first mode as explained in detail below. The first firing mechanism  110  forms an integrated unit, which is optional in the present biopsy device. The gear chassis unit  104  includes a second firing mechanism  112  for firing the biopsy needle in a second mode as explained in detail below. The right cover part  102  is formed to accommodate a flushing system for conveying liquid to the disposable unit  106  in order to eject a body tissue sample from the sample flushing chamber  109 . The flushing system includes a liquid container  114 , to which there is connected a hollow liquid transport member or tube  116 , the tube defining a bent portion  117 . In order for liquid to be conveyed from the container  114  to the sample flushing chamber  109  through the tube  116 , there is provided a peristaltic pump  118  for engaging the bent portion  117  of the tube  116 . When mounted in the right cover part  102 , the bent tube portion  117  is held firmly against the peristaltic pump  118  by means of a pair of jaws  120 ,  122 . When assembled, the left and right cover parts  100 ,  102 , the gear chassis  104  and the flushing system  114 - 122  forms a handle unit  105 , to which the disposable unit  106  is releasably securable. A locking knob  124  comprising an internal bushing  126  is provided to releasably secure the disposable unit  106  to the handle unit  105 . 
         [0114]    The liquid flushing system is disclosed further in  FIGS. 3-6 . In the external surface of right cover part  102 , there is provided indentations  128 ,  130  (see  FIG. 2) and 132  for receiving the liquid container  114 , the peristaltic pump  118  and the tube  116 , respectively. A pair of projections  134  is provided at upper and lower edge portions of indentation  128  to secure the container in the indentation  128 . The liquid container  114  and the tube  116  are disposable elements, which an operator of the biopsy device may exchange on a regular basis. Exchange of these elements do not require removal of the pump  118 , which normally remains attached to the right cover part  102  during exchange of the container  114  and tube  116 . In  FIG. 3 , the jaws  120 ,  122  are open, and the container  114  and the tube  116  are ready to be placed in the corresponding indentations  128 ,  130  and  132  formed in the right cover part  102 .  FIG. 4  illustrates the container  114  and the tube  116  accommodated in the right cover part, with the bent tube portion  117  adequately placed around the circumference of the pump  118 . In  FIG. 4 , the jaws  120  and  122  are open, whereas in  FIG. 5 , the jaws are partially pivoted to their closed position, and in  FIG. 6  the jaws  120 ,  122  are fully pivoted to their closed position, in which they keep the bent tube portion  117  in close contact with the pump  118 . When the container  114  and tube  116  are thus mounted in the right cover  102 , the free end of tube  116  is connected to a conduit in the disposable unit  106  (cf.  FIG. 2 ) for providing a fluid path from the container  114  to the sample flushing chamber  109  of the disposable unit. 
         [0115]    The first firing mechanism  110  generally illustrated in  FIG. 2  will now be further described with reference to the exploded view of  FIG. 7 . The firing mechanism  110  is arranged to fire the sample-receiving device  52  and the outer needle  50  of the biopsy device substantially simultaneously. Referring back to  FIG. 1 , the sample-receiving device  52  and the outer hollow needle  50  may thus be fired substantially simultaneously. Such simultaneous firing is useful for penetrating a suspect tissue mass, e.g. a tumor, penetration of which may be difficult due to e.g. hardness or due to a loosely supported attachment of the suspect tissue mass to surrounding tissue of the body. The loosely supported attachment may cause the suspect tissue mass to displace by pressure from the tip of the biopsy needle and to slide past the suspect tissue mass without penetrating it. It has been found that, by firing the inner and outer needles substantially simultaneously at a relatively high speed, it is possible to contact and penetrate even a loosely supported tissue mass. Below, the feature comprising substantially simultaneous firing of the outer needle and the sample-receiving device will be referred to as a “double shot”. 
         [0116]    The method of operation of the double shot firing mechanism  110  of  FIG. 7  will be described below with reference to  FIGS. 8-26 . The mechanism comprises a primary axle  136  extending longitudinally through and parallel to a longitudinal axis of compression spring  138  and through a glider  140 . A double shot frame  142  supports the spring  138  and the glider  140  between opposing wall sections  144 ,  146 . This is also visible in  FIG. 2 , from which it is also apparent that the free end  141  of glider  140  extends into the disposable unit  106  through opening  107 , the free end  141  engaging a yoke  182  (cf.  FIG. 13 ), which in turn engages a needle driver  111  fixed to the outer surface of hollow needle  50 . Below the spring  138 , a solenoid  148  extends through the frame, on the opposing side of which the solenoid extends through a nut  150 , compression spring  152  and into solenoid holder  154 . The solenoid holder  154  engages a double shot lever  156  via a solenoid-connector axle  158  extending through the lever  156  and into the solenoid holder  154 . An upper pivot pin  160  for the lever  156  is pivotally supported relative to the frame  142  and extends through frame projection  162 , whereby solenoid  148  may cause the lever  156  to pivot around pivot pin  160 . The double shot mechanism  110  further comprises a sliding rail  164 , a sliding pawl  166 , a spring pawl  168 , and an impart member  170 . Two through-going passages are provided in the impart member  170 , a first passage  172  for the solenoid-connector axle  158 , and a second passage  174  for the primary axle  136 . An impart member return spring  173  is provided between the impart member  170  and a distally facing surface  143  of the glider  140 . 
         [0117]      FIG. 8  includes structure of the biopsy device, which contributes to the double shot, i.e. substantially simultaneous firing of the outer, hollow needle  50  and the sample-receiving device  52 . The double shot firing mechanism  110 , illustrated in exploded view in  FIG. 7 , is assembled and mounted to the gear chassis unit  104  (cf.  FIG. 2 ), the gear chassis unit  104  also supporting the disposable unit  106 . In  FIG. 8 , the gear chassis unit is only partially shown for the sake of clarity. A motor-driven, toothed trigger wheel  176  is provided for causing compression of the compression spring  138  (cf.  FIG. 7 ) as explained below with reference to  FIGS. 11-17 . 
         [0118]    As shown in the end view of  FIGS. 9 and 10 , the lever  156  has two positions, an angled position as shown in  FIG. 9 , and a vertical position as shown in  FIG. 10 . The lever  156  is normally biased towards the angled position of  FIG. 9  by the compression spring  152 , the compression spring  152  being omitted in  FIGS. 9 and 10  for the sake of clarity. In case an operator of the biopsy device intends to fire the outer, hollow needle  50  and the sample-receiving device  52  substantially simultaneously, i.e. to perform a double shot, an appropriate input is provided to an electronic control system of the biopsy device, e.g. via a keypad on an external surface of the cover  100 ,  102  (cf.  FIG. 2 ). The double shot action commences by activation of the solenoid  148  to pivot the lever  156  around the upper pivot pin  160 , whereby the lever is pivoted from the angled position of  FIG. 9  to the vertical position of  FIG. 10 . 
         [0119]    Subsequently, as shown in  FIG. 11 , the trigger wheel  176  is rotated in the direction of arrow  178 . During the course of this rotation, a first bearing element  180  protruding from a surface of the trigger wheel  176  contacts the impart member  170 , whereby the impart member  170  is displaced in the distal direction along the solenoid-connector axle  158 . The stroke of the impart member  170  is defined by sidewalls of the lever. Thus, when the impart member  170  has arrived at the position shown in  FIG. 12 , further displacement thereof in the distal direction is not possible. As it will be described in detail below, this displacement of the impart member  170  causes the glider  140  (cf.  FIG. 7 ), the needle driver  111  (cf.  FIGS. 2 and 8 ) as well as outer, hollow needle  50  and the sample-receiving device  52  to be displaced in the distal direction, while the compression spring  138  is compressed, the thus compressed compression spring  138  being shown in  FIG. 12  and omitted in  FIG. 11 . The firing mechanism for substantial simultaneous firing of the inner and outer needles is now loaded. 
         [0120]    The loaded firing mechanism is illustrated in perspective view in  FIG. 13 . Compression spring  138  is loaded, and a yoke  182  has been moved to a proximal, i.e. retracted position shown in  FIG. 13 . The yoke  182  is connected to the glider  140  via a forcing pin  202  (cf.  FIG. 18 ) engaging an indentation formed in the free end  141  of the glider  140 , and the yoke  182  engages the needle driver  111 , whereby rotation of the trigger wheel  176  in the direction of arrow  178  (cf.  FIG. 11 ) causes the yoke  182  as well as the needle driver  111  and the outer needle  50  to be proximally displaced. The outer, hollow needle may thus be moved from its first extended position shown in  FIG. 8  to its second retracted position of  FIG. 13 . As further illustrated in  FIG. 13 , the yoke  182  defines a recess  184 , in which there is accommodated a slider  186 , the slider  186  having an outwardly protruding centre piece  188 . During retraction of the yoke  182 , i.e. during loading of the double shot firing mechanism, the centre piece  188  is forced downwardly to engage the bendable elongate element  66 , which is secured to the sample-receiving device  52 . The required downward movement of the centre piece  188  is caused, as the centre piece  188 , during proximal movement of the yoke engages an engagement member (not shown), which may, e.g. form part of a housing (not shown). Hence, when yoke  182  is moved in a proximal direction, the centre piece  188  is likewise displaced proximally, and in turn the bendable element  66  and the sample-receiving device  52  are moved along with the centre piece  188  of slider  186 . 
         [0121]    In the shown embodiment, the bendable element  66  comprises a toothed flexible wire or flexible rack, which is driven by an advancing gearwheel  190  (cf.  FIG. 19 ) engaging teeth of the toothed flexible wire  66 . Thus, rotation of the gearwheel  190  may cause the bendable elongate element  66  and the sample-receiving device  52  to be distally or proximally displaced, depending on the rotational direction of the gearwheel  190 . A supporting roll  192  is provided for stabilizing the flexible wire  66 , i.e. to prevent it from flexing upwardly, when it is moved in a distal direction to push the sample-receiving device  52  in the distal direction. 
         [0122]    In one embodiment, the bendable elongate element  66  is made from Nylon 6-6. The bendable elongate element may have a generally circular cross section with flattened upper and lower surfaces, so that the element forms a wire with flat upper and lower surfaces and arc-shaped right and left surfaces. For example, the diameter of the element may be approximately 1.2 mm, with a cross-sectional dimension between the flattened upper and lower surfaces being approximately 0.85 mm. In one embodiment, the outer needle  50  has an outer diameter of approximately 2.1 mm and an inner diameter of approximately 1.8 mm, the outer diameter of the sample-receiving device  52  being, in that embodiment, approximately 1.8 mm, the inner diameter of the sample-receiving device being 1.5 mm. 
         [0123]    When the impart member  170  has been moved to its proximal extremity shown in  FIGS. 12 and 13 , a spring biased release hatch  194  defining a cam  196  engages a distally facing edge on the lower surface of the glider  140  as shown in  FIG. 14 . The release hatch  194  is not visible in  FIGS. 11-13 , as it is hidden behind the lever  156  and the trigger wheel  176 . The release hatch  194  is rotationally spring biased, such that the cam  196  slides along the lower surface of the glider  140 , until the impart member  170  and thus the glider  140  have reached their proximal extremity. 
         [0124]    At this stage, rotation of the trigger wheel  176  is interrupted, and the solenoid  148  is deactivated, whereby compression spring  152  (cf.  FIG. 7 ) returns the lever  156  to the inclined position shown in  FIG. 9 . In consequence, the first bearing element  180  (cf.  FIGS. 11 and 12 ) looses contact with the impart member  170 , and the impart member return spring  173  forces the impart member  170  back to its initial position, i.e. its distal extremity, as shown in  FIG. 15 . However, as the release hatch  194  engages the glider  140  as shown in  FIG. 14 , the spring  138  is kept loaded, and hence the glider  140 , the yoke  182 , the needle driver  111 , the outer needle  50 , the slider  186 , the toothed flexible wire  66  and the sample-receiving device  52  are prevented from moving in the distal direction. The firing mechanism is now ready to fire, i.e. to release spring  138  to substantially simultaneously fire the outer needle  50  and the sample-receiving device  52 . 
         [0125]    The side elevation views of  FIGS. 16 and 17  show the device from a side opposite to the side viewed in  FIGS. 11-15 . Thus, the distal end of the device is to the left in  FIGS. 16 and 17 . Rotation of the trigger wheel  176  in the direction of arrow  178  (cf.  FIG. 11 ) is now resumed, the trigger wheel thus rotating counter clockwise in  FIGS. 16 and 17 . A second bearing element  200  attached to the trigger wheel  176  now contacts a proximal portion of the release hatch  194 , and the release hatch is thus caused to rotate clockwise in  FIGS. 16 and 17  (counter clockwise in  FIG. 14 ). As a result of this rotation, the cam  196  of the release hatch  194  moves downwardly, whereby its abutment against the glider  140  is released. The compression spring  138  is consequently released as illustrated in  FIG. 17 , and the double shot is fired. 
         [0126]    In one embodiment of the invention, the compression spring  138  for the double shot is compressed by 20-25 mm during loading of the double shot mechanism as described above, corresponding to a 20-25 mm movement of the needle  50  and the sample-receiving device. Hence, in this embodiment, the needle  50  and the sample-receiving device  52  have been displaced 20-25 mm in the distal direction between the two positions shown in  FIGS. 16 and 17 , respectively. 
         [0127]    The disposable unit  106 , incorporating several of the elements described above in connection with the double shot firing mechanism, will now be further described with reference to  FIGS. 19-26 . The disposable unit  106  includes a driving gearwheel  204  for the toothed flexible wire  66 . A cross-shaped driving axle  206  projects from a side surface of the driving gearwheel  204 , the cross-shaped driving axle  206  engaging a correspondingly shaped member in the gear chassis  104  (cf.  FIG. 2 ). The gear chassis  104  includes a motor for providing a driving force to the cross-shaped driving axle  206 . The driving gearwheel  204  is arranged to drive an first intermediate gearwheel  208 , which in turn is arranged to drive a second intermediate gearwheel  209 , which drives the advancing gearwheel  190 , the advancing gearwheel being arranged coaxially with the second intermediate gearwheel  209  in a plane adjacent the plane of the second intermediate gearwheel, whereby appropriate engagement portions are provided at opposing surfaces of the second intermediate gearwheel  209  and the advancing gearwheel  190 . These engagement portions provide a releasable interconnection, so that, before the double shot is fired, the second intermediate gearwheel  209  is brought out of engagement with the advancing gearwheel  190 . This disengagement is caused by an arm  191  forming part of the yoke  182 , which consequently moves with the yoke. When the double shot has been fired, the second gear wheel  209  and the advancing gearwheel  190  return into mutual engagement. A proximal section  67  of the toothed flexible wire  66  is widened and includes a recess  69  for engagement by a flange portion  189  of the slider  186 &#39;s centre piece  188 . The housing element  210  shown in  FIG. 18  houses a helical coiling-up groove for accommodating the toothed flexible wire  66  when the sample-receiving device  52  is retracted to its second retracted position, in which the canoe  56  is aligned with the flushing chamber  109  (cf.  FIG. 2 ). 
         [0128]    In  FIGS. 20 and 21 , the centre piece  188  of the slider  186  is lifted out of engagement with the widened proximal end portion  67  of the toothed flexible wire  66 . In this mutual position of the elements, the toothed flexible wire  66  may be moved by providing a driving force to the cross-shaped driving axle  206  by an appropriate electrical motor (not shown), which advantageously may be integrated in the gear chassis  104 . In  FIGS. 22 and 23 , the yoke  182  has been partly retracted as described above with reference to  FIGS. 9-13 , which has caused the centre piece  188  to engage the widened proximal end portion  67  of the toothed flexible wire  66 . Upon further retraction of the yoke  182 , a first yoke arm  183  engages a recess  113  in the needle driver  111 , and a second yoke arm  187  engages a recess  185  in the slider  186 , cf. also the top views of  FIGS. 24 and 25 . 
         [0129]    Following the centre piece  188 &#39;s engagement with the widened portion  67  of the toothed flexible wire, but prior to retraction of the needle driver  111  and the toothed flexible wire  66  for loading of the double shot firing mechanism (cf. the above description of  FIGS. 8-17 ), the second intermediate gearwheel  209  (cf. the above description of  FIG. 19 ) is brought out of engagement with the advancing gearwheel  190  as illustrated in  FIGS. 24 and 25 , the second intermediate gearwheel  209  engaging the advancing gearwheel  190  in  FIG. 24  and being out of engagement in  FIG. 25 . Accordingly, the driving gear mechanism for the flexible toothed wire  66  causes no resistance to the loading and releasing of the double shot firing mechanism. In an alternative embodiment, the advancing gearwheel  190  is kept in engagement with the wire  66  during loading and firing in order to stabilize the wire  66 , i.e. to prevent flexing thereof. In such an embodiment, the first intermediate gearwheel  208  (cf.  FIGS. 20-23 ) may advantageously be decoupled from the advancing gearwheel  190  in order to reduce resistance. 
         [0130]      FIGS. 25 and 26  generally depict a locking mechanism  220  for locking the driving gearwheel  204  when the needle  50  is loaded for a single shot, cf. the description of  FIGS. 27-31  below. As it will be understood, during the single shot, only the outer needle  50  is caused to be retracted and fired, while the position of the bendable elongate element  66  and the sample-receiving device  52  are locked or secured, as the locking mechanism  220  engages the cross-shaped driving axle  206 . 
         [0131]    The second firing mechanism, which causes the outer needle  50  with its distal circumferential cutting edge  60  (cf.  FIG. 1 ) to be fired in the distal direction to sever a body tissue in the canoe  56  will now be further described with reference to  FIGS. 27-31 . It will be understood that only the outer needle  50  is fired, the sample-receiving device  52  remaining unaffected by firing of the second firing mechanism  112 . This firing of the outer needle  50  will be referred to as “single shot” below. The trigger wheel  176  described above with reference to the double shot is also used in the single shot. In  FIG. 27 , the trigger wheel  176  is in the same position as depicted in  FIG. 11 . If the solenoid  148  is not activated and the double shot lever  156  is thus in the position of  FIG. 9 , rotation of the trigger wheel  176  in the direction of arrow  178  (cf.  FIGS. 11 and 27 ) does not cause the first bearing element  180  to contact impart member  170  (cf.  FIG. 11 ), as the impart member  170  is not in the plane of the bearing element  180 . Consequently, the first firing mechanism, i.e. the firing mechanism for the double shot, is not loaded. The trigger wheel  176  accordingly rotates freely to the position of  FIG. 28 . If, alternatively, the solenoid  148  is activated and the double shot lever  156  is thus in the position of  FIG. 10 , rotation of the trigger wheel from the position of  FIG. 27  to the position of  FIG. 28  causes loading and of the double shot firing mechanism as described with reference to  FIGS. 10-17 . Once the trigger wheel has arrived to the position of  FIG. 28 , and the double shot firing mechanism has optionally been loaded and fired, a third bearing element  300  protruding from a side surface of the trigger wheel  176  opposite to the surface visible in  FIG. 28  contacts an upright impart cam  302  attached to a trigger arm  304 , the arm  304  being pivotally connected to the handle unit  105  (cf.  FIG. 2 ) at a pivot  306 . At its upper end, the trigger arm  304  forms a fork  308  engaging an transmission element  310 , a proximal end of which abuts a distal end of the compression spring  62 , and a distal end of which is connected to the needle driver  111  via a pivotally mounted element  312 . 
         [0132]    The element  312  is pivotally mounted to a sliding support member  314  secured to the compression spring  62 , and it is upwardly spring-biased to the inclined position shown in  FIGS. 27 and 28 . The sliding support member  314  is connected to the trigger arm  304  via a connector  313  integral with the transmission element  310 . When the double shot firing mechanism is to be loaded as described above in connection with  FIGS. 7-26 , the element  312  is kept in a substantially non-inclined position (not shown) to allow the needle driver  111  to slide past the upper surface of the element  312 , the element  312  being forced into its non-inclined position by the yoke  182  (cf. e.g.  FIG. 13 ). 
         [0133]    Upon further rotation of the trigger wheel  176 , the trigger arm  304  is rotated around its pivot  306 , as the third bearing element  300  imparts the impart cam  302  of the trigger arm  304 , cf.  FIG. 29 . Consequently, the compression spring  62  is compressed, as a proximal end of the spring is appropriately supported. It will be appreciated that in the position of  FIG. 29 , the outer needle  50  has been retracted, whereby the canoe  56  of the sample-receiving device  52  (cf.  FIG. 1 ) is laid bare distal to the distal end portion of the outer needle  50 . The position of  FIG. 29  thus corresponds to the position of  FIG. 1 . In this position, vacuum is applied to the canoe  56  via the vacuum port  58  to suck body tissue into the canoe  56 . In  FIG. 30 , the trigger wheel  176  has rotated further to a position, in which the third bearing element  300  looses its engagement with the impart cam  302  of the trigger arm  304 , and the compression spring  62  is hence unloaded, whereby the needle driver  111  is released and shot (i.e. fired) forwardly, i.e. in the distal direction. Thereby, tissue sucked into the canoe  56  (cf.  FIG. 1 ) is severed by the circumferential cutting edge  60  of the outer needle  50 , so that a severed tissue sample is now accommodated in the canoe  56 . 
         [0134]    The single-shot firing mechanism  112  is further illustrated in the exploded view of  FIG. 31 . A supporting axle  316  extends through the compression spring  62  and is supported proximally thereof by a bushing  318  and a lock washer  320 . A distal end of the supporting axle  316  extends through the sliding support member  314 , in which it is supported by a pair of bushings  322 . A pivot pin  315  is provided for the pivotable element  312 . To ensure that the trigger arm  304  is biased in the proximal direction, a biasing mechanism  324  is mounted to the trigger arm  304  via a spring element  326 , one end of which is fixed in engagement grooves  328  provided on the trigger arm  304 . Another, opposite end of the spring element  326  is fixed to a gate element  330  forming the impart cam  302  (cf.  FIGS. 27-29 ). A compression spring  336  is provided to bias the pivotable element  312  towards an upwardly inclined position, in which it is in contact with a proximal surface of the needle driver  111  (cf.  FIGS. 27-30 ). 
         [0135]    As described above with reference to  FIGS. 27-31 , rotation of the trigger wheel  176  causes loading and firing of the single-shot firing mechanism for severing a body tissue sample, which is now collected in the canoe  56  of the sample-receiving device  52  (cf.  FIG. 1 ). Further rotation of the trigger wheel  176  causes movement of the bendable elongate element  66  (cf. FIGS.  1  and  19 - 23 ) in the proximal direction to move the canoe  56  from its first extended position, in which it is accommodated in the distal end portion of the hollow needle  50 , to its second retracted position, in which it is aligned with the flushing chamber  109  (cf. e.g.  FIGS. 27-30 ) for ejection of the body tissue sample by liquid flushing. This movement of the bendable elongate element  66  will now be further described with reference to  FIGS. 32-36 , showing a drive wheel  340 , which forms a toothed arc portion  342  and a connecting portion  344 . A free end of the connecting portion  344  is pivotally mounted to a roller  346 , which may slide in a curved track  348  formed in a carrier plate  350 . The drive wheel  340  is rotationally supported at a centre point  352  of the toothed arc portion  342 . It will be understood from  FIG. 36  that the drive wheel  340  is connected to the trigger wheel  176  via the rotational support at  352 , at which the drive wheel  340  is connected to a cam washer  354  forming a notch  356  for engagement with a reduced diameter portion  347  of the roller  346 . The cam washer  354  engages a circular element  358  secured to the trigger wheel  176 . During rotation of the trigger wheel  176  from the initial position shown in  FIG. 11  to the position shown in  FIG. 30 , the notch  356  is out of engagement with the roller  346 , and accordingly the drive wheel  340  is not rotated. Upon further rotation of the trigger wheel  176 , the notch  356  of the cam washer  354  engages the roller  346 , and thereby the free end of the connecting portion  344  of the drive wheel  340  is forced downwardly in the curved track  348 . This in turn causes the drive wheel  340  to rotate around its rotational support at  352 , whereby the drive wheel  340  is rotated from the position of  FIG. 32  to the position of  FIG. 34 . 
         [0136]    During the rotation of the drive wheel  340  as described above, the toothed arc portion  342  of the drive wheel  340  engages a gear drive, which is not shown in  FIGS. 32-34 . The gear drive, which is partly visible in  FIG. 36 , comprises a first gearwheel  360 , which is engaged by the toothed arc portion  342  of the drive wheel. The first gearwheel  360  drives a second gearwheel  362 . An axle  364  for the first gearwheel  360  is mounted in a first sleeve  366 , and an axle  368  for the second gearwheel  362  extends through a cross-shaped reinforcement member  369  and engages a connector  370 , which provides a driving force transmission interconnection to the driving gearwheel  204  (cf.  FIGS. 19-23 ) included in the disposable unit  106  (cf.  FIGS. 2 and 8 ). The disposable unit  206  also accommodates the bendable elongate element  66  for moving the sample-receiving device  52  in the hollow needle  50  ( FIG. 2 ), the flushing chamber  109 , and the coiling device  74  ( FIG. 35 ) for coiling up the bendable elongate element  66 . The driving gearwheel  204 , which is omitted in  FIG. 35  in order not to cover the coiling device  74 , drives the intermediated gearwheel  208  and the advancing gearwheel  190 , which in turn engages teeth of the bendable elongate element  66 . When the bendable elongate element  66  is moved in the proximal direction to retract the sample-receiving device for ejection of the harvested tissue sample, the bendable elongate element is coiled into the coiling device  74  forming a spiral, which allows the bendable elongate element  66  to be wound up and unwound in a controlled manner. 
         [0137]    The gear chassis  104  (cf.  FIG. 2 ) includes further elements shown in  FIG. 36 . A driving motor  372  is provided for driving the trigger wheel  176  via a gear drive  374 . A further motor  376  is provided for driving the peristaltic pump  118  (cf.  FIGS. 2-6 ) for sample ejection by liquid flush via a spindle  377  and gearwheels  378  and  379 . A glide bushing  380  is provided for the connector  370  to receive the disposable unit  106  in the handle unit  105  (cf.  2 ). A vacuum pump  382  is provided for creating vacuum suction to suck body tissue into the canoe  56  of the sample-receiving device  52  (cf.  FIGS. 1 and 2 ), the vacuum pump  382  being in fluid communication with the canoe  56  via appropriate tubes (not shown) and the vacuum port  58 . 
         [0138]    The cycle of the trigger wheel  176  described above with reference to  FIGS. 9-17  and  27 - 35  regarding double- and single shot, respectively, is diagrammatically illustrated in  FIGS. 37 and 38 .  FIG. 37  shows the cycle of the movement of the trigger wheel described in relation to  FIGS. 28-34  and back. From the position of  FIG. 28 , the trigger wheel rotates approximately 290° to the position of  FIG. 34 . During a first segment of the rotation, S-1, corresponding to the rotation of the trigger wheel  176  from the position of  FIG. 28  to the position of  FIG. 29 , the compression spring  62  is compressed. At S-2, the third bearing element  300  looses contact with the upright impart cam  302 , thereby unloading the spring  62 . The trigger wheel  176  has now rotated the cam washer  354  (cf.  FIG. 36 ) to the position, in which the notch  356  engages the roller  346 . During a subsequent segment of the rotation, S-3, the trigger wheel  176  rotates further to move the drive wheel  340  from the position of  FIG. 32  to the position of  FIG. 34  to thereby pull the sample-receiving device  52  backwards to its second retracted position, in which the canoe  56  is aligned with the flushing chamber  109  for ejection of the severed tissue sample collected in the canoe  56 . Rotation of the trigger wheel  176  is now reversed, as indicated by block arrows in  FIG. 37 . During that segment of the reverse rotation, which is denoted S-4 in  FIG. 37 , the trigger wheel  176  moves the drive wheel  340  back from the position of  FIG. 34  to the position of  FIG. 32  to thereby move the sample-receiving device  52  to the distal end portion of the outer needle  50 , i.e. to the first extended position of the sample-receiving device. At S-5, the sample-receiving device  52  is now at its distal extremity, and the notch  356  of the cam washer  354  (cf.  FIG. 36 ) disengages the roller  346 . A final segment of the reverse rotation of the trigger wheel  176 , S-6, is an idle run, in which the trigger wheel  176  is moved from a position approximately equal to the position of  FIG. 40  to the position of  FIG. 28 . Immediately prior to the termination of the S-6 rotation, the third bearing element  300  contacts and passes the impart cam  302 , which is biased in the proximal direction by the spring element  326  (cf.  FIG. 31 ). If a further tissue sample is to be severed, the above cycle may now be repeated. 
         [0139]    In  FIG. 38 , that segment of the rotation of the trigger wheel  176 , which causes the double shot described above with reference to  FIGS. 9-17 , is added to the S-1-S-6 rotation segments shown in  FIG. 37 . During a first rotation segment D-1, the trigger wheel  176  is rotated from the position of  FIG. 11  to the position of  FIG. 12  to compress the compression spring  138  (cf. e.g.  FIG. 12 ). Upon further rotation, D-2, the compression spring  138  is unloaded to substantially simultaneously fire the outer needle  50  and the sample-receiving device  52 , i.e. to move the trigger wheel from the position of  FIG. 16  to the position of  FIG. 17 . The S-1-S-6 rotation segments are now performed as described above with reference to  FIG. 37 . During a final reverse rotation segment, D-3, the trigger wheel  176  is rotated from a position, which is slightly upstream of the position depicted in  FIG. 12  (the trigger wheel rotating counterclockwise in  FIG. 12 ), to the position of  FIG. 11 . As the solenoid  148  (cf.  FIGS. 9 and 10 ) is deactivated, so that the double shot lever  156  is biased to its inclined position of  FIG. 9 , the impart member  170  is not in the plane of the first bearing element  180  (cf.  FIGS. 11 and 12 ), so that bearing element  180  may pass freely to the position of  FIG. 11  without contacting the impart member  170 . 
         [0140]    In one embodiment of the invention, the control system of the biopsy device is configured such that a double shot sequence is automatically followed by a single-shot sequence. In other embodiments, the double shot may be activated without incurring a single-shot sequence. 
         [0141]    It will be appreciated that the operation of the device, including activation of the double- and single-shot sequences described above with reference to  FIGS. 9-35 , and activation of ejection flushing, may be controlled by an operator via an appropriate touch-pad system provided e.g. on an exterior surface of the handle unit  105  (cf.  FIG. 2 ). 
         [0142]    In the embodiment described above with reference to  FIGS. 1-38 , controlling of the movement of the needle  50  and the sample-receiving device  52  is widely based on mechanical means, except for certain electronically controlled elements, such as the solenoid  148  (cf. e.g.  FIGS. 9 and 10 ), the motor  372 , vacuum pump  382  ( FIG. 36 ) and the peristaltic pump  118  for liquid flushing for tissue sample ejection. It should, however, be understood that the control system may incorporate further electronic elements. For example, the double- and single shot firing mechanisms may be driven by separate motors, which are electronically controlled, and loading and firing of the first and second mechanisms for single and double shot, respectively, may incorporate electronically controlled elements for causing appropriate engagement and disengagement of various parts. 
         [0143]      FIGS. 39 and 40  illustrate two alternative embodiments of the control system for determining the distance between the first extended position of the sample-receiving device  52  and its second retracted position, e.g. to provide automatic detection of the length of the outer hollow needle  50 . 
         [0144]    The control system uses a microcontroller  400  to constantly monitor the rotation of the motor unit  372  of the handle unit  105 . Simultaneously herewith, the system monitors, by means of an appropriate position sensor  371  (cf.  FIG. 36 ) the position of one of the transmission axles that are part of the gear system translating the movement from the motor unit to the bendable elongate element  66 . Thus, the position of the bendable elongate element may be known at all times, and the system may configure itself according to the length of the bendable elongate element, and thus to the length of the outer needle  50  (cf. e.g.  FIG. 2 ). 
         [0145]    The embodiment in  FIGS. 39 and 40  includes three sensors that are connected directly to the motor unit  372  in the handle unit  105 , and which record the rotation of the motor, cf.  FIG. 39 . These sensors may be of the Hall sensor type or of a similar type, and their output is fed into a motor driver unit  402  and a microprocessor  400 . When the motor unit  372  is activated and starts rotating, movement is translated from the motor to the bendable elongate element  66 . As long as the bendable elongate element is free to move within the lumen of the outer hollow needle  50 , a steady stream of pulses are fed from the Hall sensors to the motor driver  402  and the microprocessor  400 . When the bendable elongate element reaches the end of its movement spectrum, it arrests the motion of the motor  372  and breaks the steady stream of pulses from the sensors. This cease of impulses is recorded by the microprocessor  400 . 
         [0146]    As an additional measure, the microprocessor  400  may record the position of the aforementioned transmission axle. Information about the position of the transmission axle may be provided by a potentiometer mounted on the transmission axle. A DC signal obtained from a wiper of the potentiometer may reflect the instantaneous position of the transmission axle and the entire movement spectrum of the bendable elongate element  66  corresponding to an angle of rotation of 300 degrees. Since the position of the axle when the bendable elongate element  66  reaches its second retracted position is recorded—and may be found again by means of the output from the potentiometer—the microprocessor  400  may reduce the wear on the motor by gradually reducing its speed and stopping it immediately prior to reaching the position corresponding to the second retracted position of the bendable elongate element  66 . 
         [0147]    An alternative or complement to measuring the rotation of the motor  372  directly is to measure motor current passing through the motor. Results of this measurement may be transmitted to a microcontroller or microprocessor wherein a suitable microprocessor program or software comprises a pre-defined current threshold. This measurement of motor current may be done with a sampling A/D converter integrated with the microcontroller or a corresponding external device. As long as the bendable elongate element  66  is free to move within the lumen of the outer hollow needle  50 , the load on the motor is substantially constant, and thus the motor current is also constant. When the load increases because the rod or rack has reached either end of its movement spectrum, the motor current increases. When the current reaches a pre-defined threshold value, the current change is recorded by a motor driver unit that is an integrated part of the control system. Simultaneously, the microcontroller may record the position of the transmission axle. Information about the position of the transmission axle may be provided by a suitable electrical or optical signal derived from e.g. a potentiometer. 
         [0148]    A third means of transmitting Information about the length of the bendable elongate element  66  to the microcontroller is to use a mechanical means, such as a spring-loaded pin that slides into a recess in the bendable elongate element  66  or the sample-receiving device  52 . Also optomechanical means may be utilized. 
         [0149]    While the present invention has been described with reference to one of more particular embodiments, those skilled in the art will recognize that many changes may be made thereto without departing from the spirit and scope of the present invention. Each of these embodiments and obvious variations thereof is contemplated as falling within the spirit and scope of the claimed invention, which is set forth in the following claims.