Patent Description:
Medical procedures frequently involve the insertion of a probe into the tissue of a patient. In order to assist the medical practitioner correctly insert and position the probe, probe placement into a patient's body is often done under the guidance of ultrasound. The use of ultrasound creates a picture of the internal tissue using sound waves, assisting the clinician in guiding the probe to the tissue to be sampled. However, despite having a picture of the internal tissue, an image of the probe is often hard to reproduce due to the typically thin dimensions of the probe. Thus, accurate placement of the probe tip into the tissue is difficult, especially at steep angles and deep target locations. In addition, a relatively large amount of force is often required to insert the probe into the tissue. There is therefore a risk that the probe is bent during insertion. This may cause discomfort to the patient.

<CIT> discloses a system comprising a piezoelectric driver unit attached to the base of a needle, so that in use the piezoelectric driver imparts a longitudinal vibration to the needle enabling it to be seen by a conventional medical ultrasound imaging system. The system is designed for medical procedures such as biopsies and enables the needle to be more clearly seen on an ultrasound imaging system.

The system of <CIT> is limited to vibrations up to <NUM> in frequency, and does not operate in the ultrasonic range. The piezoelectric driver is offset from the base of the needle and connected to it by means of an armature, which moves in a wagging fashion and produces flexural as well as longitudinal oscillations in the needle. The device is solely concerned with visualization of the needle tip under ultrasound, and does not address the problem of reducing needle force.

<CIT> discloses an ultrasonically actuated medical implement, comprising:.

The probe member is typically gripped in a collet or similar mechanism.

<CIT> discloses a medical tool for reduce penetration force with feedback means.

<CIT> discloses a medical tool for reduced penetration force.

<CIT> discloses a needle location for use with an ultrasound imager.

The present invention addresses these and other limitations of the prior art.

According to the present invention, there is provided a device for use in a medical procedure, as claimed in claim <NUM>.

The elongate member-transducer connection may provide efficient energy transfer from the transducer to the elongate member by providing a secure connection point between the elongate member and the transducer. In addition, vibrating the elongate member reduces the amount of force require to insert the probe into body tissue during medical procedures.

The transducer may be configured to vibrate the elongate member in a lengthwise direction.

The lengthwise direction may be a longitudinal direction. Longitudinal vibration may further reduce the force require to insert the elongate member into body tissue. The amount of deflection of the elongate member upon insertion is also be reduced.

The connection arrangement may comprise a male connection member and a female connection member. The male connection member and female connection member may be configured to mate with each other. The male connection member may be on the elongate member. The female connection member may be on the transducer. The male connection member may be on the transducer. The female connection member may be on the elongate member. Corresponding male and female connection members may provide a secure connection means.

The connection arrangement may comprise a screw mechanism. A screw mechanism may provide a large point of contact between the elongate member and the transducer. This helps ensure that there is a secure and stable connection between the elongate member and the transducer. A larger point of contact also provides more reliable transmission of vibrations from the transducer to the probe. Thus there is less loss of energy, making the connection more efficient in transferring energy.

The elongate member may comprise an externally threaded portion. The transducer may comprise an internally threaded portion. The elongate member may comprise an internally threaded portion. The transducer may comprise an externally threaded portion. The threaded elongate member portion is suitably configured to mate with the threaded transducer portion. This may allow the elongate member to be screwed into the transducer for connection to the transducer. Thus the probe may be screwed into the transducer or the transducer may be screwed into the elongate member.

Alternatively, the connection arrangement may comprise a bayonet mechanism. The connection arrangement may comprise a snap-fit mechanism. Both a bayonet and snap-fit connection mechanism may provide a large, secure point of contact between the elongate member and transducer and do not rely on the provision of compression, or a gripping mechanism, to secure the probe to the transducer.

The elongate member may be connected to the transducer using a connection member. The connection member may be connected between the probe and the transducer. The connection member may be an additional, intermediate component between the elongate member and the transducer. The elongate member may be connected to the connection member using a screw mechanism. The elongate member may be connected to the connection member using a bayonet mechanism. The elongate member may be connected to the connection member using a snap-fit mechanism. The elongate member may be connected to the connection member using a clip mechanism. The transducer may be connected to the connection member using any of the aforementioned connection means.

The elongate member and transducer may be connected to the connection member using the same or different connection means.

The connection member may be a clip. The clip may comprise a first and a second gripping end. The first gripping end may be configured to attachment to the probe. The second gripping end may be configured for attachment to the transducer. The first and second gripping ends may be first and second arms. The first and second arms may be curved. The clip may be made of any suitable material, including metal or a plastics material.

The provision of an intermediate connection member may allow the elongate member and transducer to be connected together without the need to redesign either the elongate member or the transducer to allow the connection to happen. Thus any elongate member may be connected to any transducer. Thus, the transducer may be configured to vibrate any elongate member , through the use of the connection member, and a specially designed elongate member does not need to be used.

The elongate member may be a needle-like structure. The elongate member may be a needle. Needles are medical devices that are frequently used during medical procedures. The elongate member may be an ablation probe. The needle may be a biopsy needle. The needle may be a drug delivery needle. The needle may be an in vitro fertilization needle. The needle may be a vacuum assisted biopsy needle. The needle may be an amniocentesis needle. The needle may be a chorionic villus sampling needle. The needle may be for venous or arterial access. The needle may be for stent placement.

The needle may be a hollow needle. The hollow needle may comprise a passage configured to allow fluid to pass through the needle. This may allow the hollow needle to be used for injecting fluid into body tissue.

The transducer may comprise a channel configured to allow fluid to pass through the transducer. This allows the hollow needle to be connected to the transducer so that fluid may pass through the transducer into the hollow needle. Thus, the transducer may be used to vibrate the hollow needle during fluid injection procedures.

A tube may be configured to be inserted into a channel of the transducer. The tube may be a sterile tube. The tube may have first and second ends, the first and second ends being sealed. This may ensure that the tube environment remains free from contaminants and ensures that the inside of the tube remains sterile.

The elongate member may be configured to be attached to a first end of the sterile tube and a syringe may be configured to be attached to a second end of the sterile tube. Thus, a hollow needle may be configured to be attached to the first end of the tube. This provides a sterile environment for transferring fluid present in the syringe, through the transducer, and into the hollow needle.

The needle may be a solid needle. The solid needle may comprise a solid wire and a hollow tube that surrounds and covers the solid wire. The solid needle may comprise a stylet and a cannula. The stylet may also comprise a sample notch. The solid needle may be used to perform biopsies and the sample notch may be used to collect the tissue sample.

The system of the invention is designed to vibrate the elongate member longitudinally. When a sample notch is present, the needle also flexes at the resonance which has an advantage. Increasing the vibration amplitude can highlight the two ends of the notch under ultrasound visualization allowing the practitioner to align the sample notch with the tumour.

The cannula may comprise a tip. The cannula tip may be symmetric about a central longitudinal axis of the cannula. A symmetric cannula reduces flexural motion when the needle is being vibrated by the transducer. A symmetric cannula tip is advantageous especially in embodiments in which the connection of stylet to transducer is via a screw mechanism, in which the orientation of the sample notch is unpredictable. A symmetric cannula tip allows cutting of tissue irrespective of the of position of the stylet notch.

The cannula may comprise a cutting tip. For example, the distal end of the cannula may feature a bevel, angle, or point.

The stylet may comprise a tip. The stylet tip may be symmetric about a central longitudinal axis of the stylet. A symmetric stylet reduces flexural motion when the needle is being vibrated by the transducer.

The sample notch of the solid needle may be symmetric about a central longitudinal axis of the sample notch. A symmetric sample notch may reduce flexural motion when the needle is being vibrated by the transducer.

The stylet may be configured to be connected to the transducer via the connection arrangement.

The stylet includes an integral hub. Thus, the connection member may comprise a hub. The hub may provide a convenient means of connecting the stylet to the transducer. This avoids the need for the connection mechanism to actually be present on the stylet. This may reduce the risk of damage to the stylet.

The stylet hub may comprise a base portion. Thus, the connection member may be a base portion of a stylet hub. The stylet may be configured to be attached to the base portion of the stylet hub. The stylet may be attached to the base portion of the stylet hub via a hole in the base portion of the hub. Thus, a length of the stylet may extend into the hole in the base portion of the hub. The base portion may be used to attach the stylet to the transducer. Thus, the base portion may provide a separate portion of the stylet to be connected to the transducer which may help prevent damage of the stylet as a result of the connection mechanism.

The stylet may be attached to the base portion of the stylet hub by a brazed joint. The stylet may be attached to the base portion of the stylet hub by a welded joint. The stylet may be attached to the base portion by melding. The stylet may be attached to the base portion using an adhesive. These joints may provide a secure method of attaching the stylet to the hub.

Preferably, the stylet hub comprises an externally threaded portion, extending from the base portion. The externally threaded portion of the stylet hub may be configured to engage with an internally threaded portion of the transducer. Alternatively, the stylet hub may comprise an internally threaded portion which may be configured to engage with an externally threaded portion of the transducer. This provides a simple and convenient method of attaching the stylet to the transducer.

The device may comprise a locking nut. The locking nut may be used to retain the stylet while the stylet is being connected to the transducer. Thus, the locking nut may be used to hold the stylet in place while the transducer is attached to the stylet which may help make the attachment process easier. The locking nut therefore helps the user connect the stylet to the transducer.

The locking nut preferably comprises a socket portion. The socket portion may be used to attach the locking nut to the stylet. The socket portion may be used to hold the stylet in place while the transducer is being attached to the stylet.

An internal surface of the socket portion may be shaped to correspond to an external perimeter of the base portion of the stylet hub. This ensures that the socket portion fits securely over the base portion of the stylet hub. This improves the grip that the socket portion has on the stylet hub which facilitates connecting the stylet to the transducer. The socket portion may comprise a metal insert. The metal insert may be shaped to correspond to an external perimeter of the base portion of the stylet hub to provide improved grip of the socket portion on the stylet hub.

The base portion of the stylet hub preferably has a substantially hexagonal shaped cross section. The socket portion may have a substantially hexagonal shaped cross section. Alternatively, socket portion may have a substantially octagonal shaped cross section. The socket portion may have a substantially regular polygonal shaped cross section. A polygonal cross section provides suitable grip between the base portion and the socket portion. This ensures that the stylet does not rotate while the transducer is being screwed onto the stylet, and makes the process of screwing in the stylet hub easier.

The base portion of the stylet hub and the socket portion of the locking nut are preferably configured to releasably engage. Thus the locking nut may be attached as and when needed.

The locking nut comprises an external surface. The external surface preferably comprises a grippable portion. The grippable portion may be on a portion of the external surface. Alternatively, the grippable portion may extend across the entire external surface. The grippable portion assists the user to securely grip the locking nut.

The grippable portion preferably comprises a plurality of grooves. Grooves may be formed in the locking nut at the same time the locking nut is made. Thus, a separate manufacturing step is not necessary to provide the grippable portionThe grippable portion may comprise knurling. The grippable portion may comprise any other suitable gripping mechanism.

The locking nut preferably comprises a longitudinal slit along a length of the locking nut. The longitudinal slit may extend along the entire length of the locking nut. The slit allows the locking nut to be inserted around the stylet of the needle. This permits the locking nut to be attached to the stylet without the need to disassemble the needle device, and removed in the same way.

The amplitude and/or frequency of the current supplied to the transducer may be manually controlled by a user. The user may control the voltage using a control panel. This may allow the user to adjust the voltage so that it is optimised for different types of probe. Thus, the user may ensure that the probe being used is being vibrated at or near its resonant frequency.

The device may further comprise a protective sheath. The protective sheath may be configured to enclose the transducer. The sheath may be a sterile sheath. This may ensure that the transducer does not get contaminated during medical procedures so that the transducer may be re-used.

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which:.

<FIG> shows an embodiment of the inventive device <NUM>. Here, the vibrating device <NUM> is a vibrating needle device <NUM>. The device <NUM> comprises a needle <NUM> which is contained within a needle housing <NUM>. The needle <NUM> is connected to a transducer <NUM> which is contained within a transducer housing <NUM>. The needle housing <NUM> and transducer housing <NUM> are therefore connected together. The needle <NUM> is connected to an ultrasound generator unit <NUM> via the transducer <NUM>. A foot switch <NUM> is connected to the generator unit <NUM> to allow the user to activate the generator unit <NUM>. The ultrasonic generator unit <NUM> vibrates the needle <NUM> at its resonant frequency using ultrasound.

The needle <NUM> described herein may be used for a variety of deep tissue applications, including but not limited to kidney, liver, and lung.

Referring to <FIG>, the needle comprises a stylet <NUM> and a cannula <NUM>. The stylet <NUM> is a solid inner needle which comprises a cutting tip <NUM> at one end and a sample notch or notch <NUM> positioned part way along a length of the stylet <NUM>. The tip <NUM> is used to cut through the layers of tissue and the sample notch <NUM> is used to collect the tissue sample. Referring to <FIG>, the cannula <NUM> is a hollow tube which has a cutting edge <NUM> at one end. The cannula <NUM> cuts the desired tissue sample to be carried in the sample notch <NUM>. The cannula <NUM> surrounds the stylet <NUM> and is configured to be movable, relative to the stylet <NUM>. For example, <FIG> shows the cannula <NUM> in an extended configuration, in which the cannula <NUM> surrounds substantially the whole length of the stylet <NUM>. <FIG> shows the cannula <NUM> in a withdraw configuration, in which the cannula <NUM> has exposed a portion of the stylet <NUM>, in this case the tip <NUM> and sample notch <NUM>. The cannula <NUM> is provided with graduation markings <NUM> along the length of the cannula <NUM>. The graduation markings <NUM> are circumferential rings equally spaced along the length of the cannula <NUM>, however any other suitable means of providing a visual marking may be used. The graduation markings <NUM> provide the user with a mechanism to keep track of the depth of insertion and so are used to indicate to the user the depth of the cannula <NUM> inside the tissue. The graduation markings <NUM> are centimetre markings, however any other suitable measure could be used instead.

The vibrating needle <NUM> can be used to perform biopsies. The design of the needle <NUM>, including the cannula <NUM> and stylet <NUM>, varies depending on the type of biopsy procedure being undertaken. The two main types of procedure are Endcut biopsy and Trucut biopsy. Conventional Trucut biopsy requires first extending the stylet <NUM> from the cannula <NUM>. The stylet <NUM> is then inserted, or pushed, into the tissue specimen. Whilst the stylet <NUM> is still inside the tissue, the cannula <NUM> is then slid over the stylet <NUM> to cut out a sample of the tissue. The tissue sample is contained within the sample notch <NUM> of the stylet <NUM>. The cannula <NUM> and stylet <NUM> are then withdrawn from the tissue, the cannula <NUM> still covering the stylet <NUM>.

A risk with conventional Trucut biopsy is that if the tissue specimen of interest is benign, for example the tissue feels stiffer or rubbery, the user is required to apply more than the usual amount of force to push the stylet <NUM> into the tissue. This may cause the tip of the stylet <NUM> of the needle <NUM> to bend or even break. A needle bending inside a patient could be painful for the patient whilst a broken needle tip could necessitate a surgical procedure to recover the broken piece of the tip.

To avoid the risk of bending or breaking the needle, the needle device <NUM> described herein has been designed based on the sheathed needle biopsy technique. Here, the stylet <NUM> is pushed into the tissue whilst the cannula <NUM> still covers the stylet <NUM>. That is, the cannula <NUM> is not pulled back over the stylet <NUM> to expose the stylet <NUM> prior to insertion. Thus the stylet <NUM> and cannula <NUM> are inserted into tissue together and at the same time. Once inside the tissue, the cannula <NUM> is withdrawn by pulling the cannula <NUM> back so that it slides back over the stylet <NUM>, exposing the stylet <NUM>. The cannula <NUM> is then pushed forward so that it is slid back over the stylet <NUM> to cut out a sample of the specimen, as with the conventional Trucut technique. Both the stylet <NUM> and the cannula <NUM> are then withdrawn from the tissue.

The size of the cannula <NUM> is determined by its gauge and length. The length of the cannula <NUM> represents the working length of the cannula <NUM> i.e. the exposed length of the cannula <NUM>. The gauge of the cannula <NUM> is <NUM>, however it will be appreciated that any other suitable gauge may be used as illustrated in <FIG>. The gauge of the needle <NUM> is partly determined by the needle <NUM> behaviour under the influence of ultrasound vibration. In general, a thicker needle <NUM> is more compatible with the various modes of ultrasonic vibration. The length of the cannula <NUM> is <NUM>, however it will be appreciated that any other suitable length may also be used as illustrated in <FIG>. The length of the cannula <NUM> is chosen such that it may be used with a variety of insertion depths.

The tip <NUM> of the cannula has cutting edges <NUM> to assist in cutting the tissue sample. The orientation of the cannula tip <NUM> with respect to the orientation of the sample notch <NUM> is therefore relevant. As shown in <FIG>, the cannula tip <NUM> is symmetric about a central longitudinal axis of the cannula <NUM>, which coincides with a central longitudinal axis of the needle <NUM>. A symmetric design is advantageous because otherwise it will be difficult for the user to ensure the alignment of the sample notch <NUM> with the cutting edges <NUM>, due to the asymmetric nature of the sample notch <NUM> design. A symmetric design of cannula tip <NUM> therefore ensures that the tip design is independent of the orientation of the sample notch <NUM>. As can be seen in <FIG>, the cannula tip <NUM> has a round, tapered design. However, it will be appreciated that any other suitable tip design may be used. For example, the tip may be single-curved, double-curved, or quad-curved, as illustrated in <FIG>.

The tip <NUM> of the stylet of the needle <NUM> has a multifaceted design, as can be seen in <FIG>. Here, the pointed tip <NUM> of the stylet <NUM> is central to the stylet <NUM> and needle <NUM>. That is, the pointed tip <NUM> coincides with a central longitudinal axis of the style <NUM> and needle <NUM>. The facets <NUM> are bevelled facets. The bevelled facets <NUM> are positioned around the central needle point <NUM>, or stylet tip <NUM>, in a symmetric layout. That is, the tip <NUM> of the needle is symmetric about a central longitudinal axis of the stylet <NUM>, which coincides with a central longitudinal axis of the needle <NUM>. Multiple facets provide multiple sharp edges to aid tissue cutting as the needle <NUM> is inserted into the tissue. A symmetric tip design is preferred as the symmetry helps reduce the production of transverse modes of vibration, which are encouraged through non-symmetries. In other embodiments, different tip designs may be used. For example the tip may be tri-bevelled, quad-bevelled, a pencil point, monofaceted, or any other suitable tip design, as shown in <FIG>.

The sample notch <NUM> is a section of the stylet <NUM> in which the tissue sample is collected during the biopsy, after the tissue has been cut. The sample notch <NUM> is typically <NUM> in length, however any other suitable length of sample notch may be used. The sample notch <NUM>, or sample notch <NUM>, of the needle <NUM> has symmetric core structure, as shown in <FIG>. That is, the sample notch <NUM> is symmetric about a central longitudinal axis of the stylet <NUM>. The notch <NUM> is located part way along the stylet <NUM> towards the tip <NUM> of the stylet but spaced apart from the tip <NUM> of the stylet. Thus the tip <NUM> of the stylet and the sample notch <NUM> are separate from each other.

Any non-symmetry about a central, longitudinal axis of the stylet <NUM> leads to flexural motion at the tip of the stylet <NUM> thus it is important that the design of the stylet is symmetric along the entire length of the stylet. However, due to the change in the thickness of the stylet <NUM> before and after the notch <NUM>, the stylet typically has a mechanically weak region which, besides having high mechanical stresses, introduces transverse modes of vibration. Both the mechanical stresses and flexural motion can lead to needle breakage during ultrasonic vibration.

A notch design which adds strength to the needle structure <NUM> is therefore preferred. In addition, since large sample volumes of tissue are preferred for better diagnosis, the volume of the sample notch <NUM> is also taken into account. Thus, to increase the strength of the needle <NUM>, the notch <NUM> is coated in a high-quality surface finish (for example, having roughness value between <NUM> and <NUM>), to help avoid mechanical stresses. However, in other embodiments, the needle <NUM> may be polished, or electro polished, to produce a high-quality surface finish. In other embodiments, the needle <NUM> is cut to have a high-quality surface finish. A high-quality of surface finish is important for longevity of the needle <NUM> as grooves at rights angles to the length of the needle <NUM> can cause weak points which may lead to failure of the needle <NUM>.

Although a core sample notch design has been chosen, it will be appreciated that many other suitable notch designs may also be used. For example, the sample notch may be a single-sided notch, a reinforced single-side notch, a double-sided notch, or a planar notch, as illustrated in <FIG>.

Referring to <FIG>, the needle housing <NUM> comprises a main body <NUM> and an end cap <NUM>. The main body <NUM> of the housing encases the cannula <NUM> and stylet <NUM>, as well as a trigger mechanism <NUM> for actuating insertion of the needle <NUM> into the tissue, allowing the tissue sample to be taken. This configuration is illustrated in <FIG>. The end cap <NUM> of the housing <NUM> connects the needle housing <NUM> to the transducer <NUM>.

The main body <NUM> of the housing is a substantially cylindrical, hollow body. The main body of the needle housing is formed from two parts <NUM>, <NUM>, as shown in <FIG>. The two parts are identical to each other. Each part forms half a shell of the main body <NUM> of the housing. The housing body <NUM> is therefore made from two concave shell portions <NUM>, <NUM>. The two shell portions <NUM>, <NUM> are joined together along their respective edges to form the substantially hollow cylindrical housing body <NUM>, as shown in <FIG>.

The shells <NUM>, <NUM> are joined together using ultrasonic welding, although any other suitable joining process may also be used. To help with alignment of the two shell portions before they are joined together, each portion is provided with a pin and hole arrangement, as shown in <FIG>. A first side 38a of the first shell <NUM> comprises a plurality of pins 40a, or protrusions 40a, along an outer edge 38a while the other side 42a of the first shell <NUM> comprises a plurality of holes 44a along the other outer edge 42a. Corresponding second shell <NUM> has holes 44b along its first edge 38b and pins 40b along its second edge 42b. The holes 44b and pins 40b on the second shell portion <NUM> correspond to the pins 40a and holes 44a on the first shell <NUM>. The pins <NUM> are inserted into the holes <NUM> when the two parts <NUM>, <NUM> are joined together to ensure accurate alignment. The two parts, or shells, are injection moulded and made of plastic. However, any other suitable material and manufacturing process may be used.

Referring to <FIG>, the main body <NUM> of the housing comprises a first, or front, end <NUM> and a second, or rear, end <NUM>. The rear end <NUM> of the main body comprises a grippable portion <NUM>. The grippable portion <NUM> is a portion of the external surface of the main housing body <NUM> which comprises a grooved pattern to help the user grip the housing. The grooved pattern comprises a series of equally spaced apart circumferential ridges <NUM> which extend radially from the external surface of the housing <NUM>. The ridges <NUM> are positioned at the rear end <NUM> of the main body and extend part way along a length of the main body <NUM> of the housing. Thus the ridges <NUM> do not extend of the whole of the external surface of the main body <NUM>.

The body of the housing comprises a slot <NUM> to receive a trigger button <NUM>. The slot <NUM> is positioned part way along the length of the body in-between two ridges <NUM>. Thus, the slot <NUM> is positioned within the grooved pattern <NUM> of the main body <NUM>. The slot <NUM> is configured so that the trigger button <NUM> extends radially through the body <NUM> of the housing allowing the user to actuate the trigger mechanism <NUM>.

On an internal surface of the main body <NUM>, substantially next to the trigger slot <NUM>, is a trigger catch <NUM>. The catch <NUM> is a protrusion which extends into the hollow portion of the main body. The catch <NUM> comprises a substantially flat surface <NUM> at one end, the flat surface <NUM> substantially perpendicular to a longitudinal axis of the main body <NUM>. The catch <NUM> also has a sloped surface <NUM> which tapers towards the internal wall of the main body <NUM>, as can be seen in <FIG>. The catch <NUM> is configured to engage a trigger lever <NUM> as will be explained in more detail later.

Towards the front end <NUM> of the main body <NUM> are slots <NUM> for receiving a trigger lever, as illustrated in <FIG>. As can be seen in <FIG> and <FIG> there are two slots 62a, 62b substantially opposite to each other radially. The slots <NUM> extend longitudinally along a portion of the main body <NUM>, terminating at the grippable portion <NUM> of the main body <NUM>.

Referring to <FIG>, the end cap <NUM> of the needle housing <NUM> is substantially cylindrical having a first, or front, end <NUM> and a second, or rear, end <NUM>. The front end <NUM> is connected to the main body <NUM> of the housing and the rear end <NUM> is connected to the transducer housing <NUM>.

The cap <NUM> is a single component which has been injection moulded; however, any other suitable manufacturing process could also be used. The front end <NUM> of the cap is a substantially closed end having a small central passage <NUM> through the end potion <NUM>. The front end <NUM> of the cap is ultrasonically welded to the rear end <NUM> of the main body of the needle housing. An alignment groove <NUM> and projection <NUM> are present on the front end <NUM> of the cap. The alignment projection <NUM> is a circumferential projection <NUM>. The alignment groove <NUM> may be a circumferential groove <NUM>. The alignment projection <NUM> corresponds to an alignment slot <NUM> on the rear end <NUM> of the main housing body <NUM>. The alignment grooves <NUM> and projections <NUM> help position the end cap <NUM> accurately on main housing body <NUM>.

The rear end <NUM> of the end cap is substantially open-ended. Thus the rear end <NUM> of the end cap is a hollow cylindrical portion which extends longitudinally away from the surface of the front end <NUM>. The hollow cylindrical portion is internally threaded <NUM> so that it can be attached to the transducer housing <NUM>.

The trigger mechanism <NUM> comprises a trigger lever <NUM> and a trigger button <NUM>. The trigger mechanism <NUM> is configured such that it can be operated single-handed.

The trigger lever <NUM> comprises a base portion <NUM>. The trigger lever <NUM> comprises a hollow passage <NUM> which extends through the base portion <NUM>, as shown in <FIG>. The hollow passage <NUM> is in the centre of the lever. The hollow passage <NUM> allows the stylet <NUM> to be passed through the trigger lever <NUM>, as can be seen in <FIG>, so that the trigger lever <NUM> can move relative to the stylet <NUM>. The hollow passage <NUM> is also configured to receive an end of the cannula <NUM>. The cannula <NUM> is positioned around the stylet <NUM>, inside the hollow passage <NUM>. The cannula <NUM> is attached to the inside of the hollow passage <NUM> so that the cannula <NUM> is attached to the trigger lever <NUM>. The cannula <NUM> is attached to the lever <NUM> via a suitable UV-cured adhesive. However, any other suitable method of securely attaching the cannula could be used. Attaching the cannula <NUM> to the trigger lever <NUM> ensures that the cannula <NUM> moves when the trigger lever <NUM> moves. This also allows both the trigger lever <NUM> and the cannula <NUM> to move relative to the stylet <NUM>.

The trigger lever <NUM> comprises a lever catch <NUM> which extends longitudinally from the base portion <NUM>. The lever catch <NUM> is configured to correspond to the trigger catch <NUM> inside the main body <NUM> of the needle housing <NUM>. Thus, the lever catch has a front sloping, or angled, surface <NUM> and a rear flat portion <NUM>. The lever catch <NUM> and the trigger catch <NUM> are releasably coupled using a snap-fit connection.

The trigger lever <NUM> comprises a plurality of buttons <NUM>, or panels <NUM>, positioned on either side of the base portion <NUM>. As can be seen in <FIG> the lever <NUM> has two panels <NUM> positioned substantially opposite each other radially. The panels <NUM> allow the user to pull the trigger lever <NUM> back, against a primary spring <NUM>, until the lever catch <NUM> has engaged with the trigger catch <NUM> in the main body <NUM> of the needle housing, as shown in <FIG>. Pulling the trigger lever <NUM> back causes the cannula <NUM> to be pulled back over the stylet <NUM>, exposing the stylet <NUM>. When the trigger <NUM> is subsequently released, the cannula <NUM> will be pushed forwards back over the stylet <NUM>. The primary spring <NUM> is connected to the trigger lever <NUM> using a spring support <NUM>. The spring support <NUM> is a longitudinally extending portion which extends from the base portion <NUM> of the trigger lever <NUM>. The spring support <NUM> passes through the centre of the spring <NUM> to support the spring <NUM>.

Referring to <FIG>, the trigger button <NUM> comprises a rounded end <NUM> and an engaging end <NUM>, the two end portions being substantially opposite each other. Between the two end portions is a radially extending flange <NUM>. The trigger button <NUM> is positioned within the trigger button slot <NUM> of the main housing body <NUM> and the rounded end <NUM> is configured to protrude from the main housing body <NUM>, through the trigger button slot <NUM>, as shown in <FIG>. A secondary spring <NUM> is positioned around the trigger button <NUM> inside the trigger slot <NUM>. The trigger button flange <NUM> rests on top of the secondary spring <NUM>. The secondary spring <NUM> biases the trigger button <NUM> so that it protrudes from the needle housing <NUM>. The flange <NUM> acts as a stopper and prevents the secondary spring <NUM> from forcing the trigger button <NUM> out of the trigger slot <NUM>. The user presses the trigger button <NUM>, against the biasing force of the secondary spring <NUM>, so that the engaging portion <NUM> extends into the internal portion of the main housing body <NUM>.

When the trigger button <NUM> has been depressed, the engaging end <NUM> is configured to interact with the lever catch <NUM> on the trigger lever <NUM>. The engaging end <NUM> comprises an angled surface <NUM> which is configured to interact with the angled surface <NUM> of the lever catch <NUM>. When the engaging end <NUM> is forced into the main housing body <NUM> through the action of the user pressing the trigger button <NUM>, the angled surface of the trigger button <NUM> presses on the angled surface of the lever catch <NUM>, as shown in <FIG>. This forces the lever catch <NUM> to bend radially towards the internal portion of the main housing body <NUM> so that the lever catch <NUM> and trigger catch <NUM> disengage. Once the two catches are disengaged, the trigger lever <NUM> is released. The action of the primary spring <NUM> then forces the trigger lever <NUM> towards the front end <NUM> of the needle housing, which in turn moves the cannula <NUM> forwards.

A second spring support <NUM> is configured to hold one end of the primary spring <NUM> at the rear end <NUM> of the needle housing while the other end of the spring <NUM>, support by the trigger spring support <NUM> at the front end <NUM> of the housing, is compressed and released during the trigger/release operation. Referring to <FIG>, the second spring support <NUM> comprises a substantially flat base <NUM> from which a supporting portion <NUM> extends. The end of the spring <NUM> is configured to be inserted over the spring supporting portion <NUM>. A hollow passage <NUM> passes centrally through the spring support <NUM> to allow the stylet <NUM> to pass through the spring support <NUM>.

The flat base <NUM> of the spring support <NUM> is contained within the end cap <NUM> of the needle housing. The spring support <NUM> extends through the passage <NUM>, or hole <NUM>, in the front face <NUM> of the end cap. The spring support <NUM> stops the primary spring <NUM> from bending during the lever cocking process.

The primary <NUM> and secondary springs <NUM> are compression springs. The wire thickness and dimensions of the primary spring <NUM> are chosen in particular so that it replicates the stiffness constant of the compression spring used in conventional biopsy needles. For the secondary spring <NUM>, the dimensions are chosen so that the spring easily fits into the needle housing trigger slot <NUM> and allows the user to gently push the trigger lever <NUM> out of the trigger catch <NUM>. The springs are made from stainless steel, although any other suitable metal may be used.

Referring to <FIG>, the transducer <NUM> is a standard Langevin sandwich piezoelectric transducer. The transducer <NUM> is configured to resonate the stylet <NUM> in a longitudinal mode, or direction, with an amplitude of ≤ <NUM> at a frequency in the range <NUM> to <NUM>. This frequency range provides a balance between transducer size and large vibration amplitude. The resonant, or driven, frequency of the needle device is <NUM>. This is defined by the frequency of the stylet <NUM> at which the longitudinal vibration mode is achieved. Pure longitudinal modes are preferred. This is because any asymmetry present in the stylet, especially at the notch area, produces mode coupling between longitudinal and flexural modes.

The user controls the amplitude of vibration using the ultrasound generator unit <NUM>. However, the maximum amplitude of vibration is limited to ≤ <NUM> to avoid unnecessarily large vibrations in the needle structure and to meet the condition fD ≤ PRF/<NUM> of the conventional ultrasound imaging system, where fD is the Doppler shift frequency and PRF is the pulse repetition frequency. When this condition is met, the aliasing effect on the Doppler ultrasound can be avoided.

The Doppler shift frequency depends on the resonant frequency of the transducer <NUM>, the vibration velocity at the tip of the needle <NUM>, and the needle insertion angle or insonation angle. The pulse repetition frequency is an ultrasound system specific parameter, typically <NUM>. If the Doppler shift frequency is higher than half of the pulse repetition frequency value then aliasing, an artefact, occurs on Doppler ultrasound which can affect the accuracy of tip visibility.

The transducer <NUM> comprises a front mass <NUM> and a back mass <NUM>. The front mass <NUM> is a hollow cylinder having a passage <NUM> passing through a portion of the front mass <NUM>. The passage <NUM> in the front mass <NUM> is internally threaded at a front end <NUM> to allow the needle <NUM> to be attached to the transducer <NUM>. The front mass <NUM> comprises a flange <NUM> which extends radially away from the front mass <NUM>. The flange <NUM> is positioned at a rear end <NUM> of the front mass <NUM>, opposite to the front end <NUM> at which the needle is attached, as shown in <FIG>. The flange <NUM> comprises two flat portions <NUM> on the perimeter of the flange <NUM>, as shown in <FIG>. The flat portions <NUM> are anti-rotation portions to prevent the transducer <NUM> from rotating during the needle attachment process. That is, when the needle hub is being screwed into the front mass of the transducer, the transducer will be prevented from rotating during the screw tightening by way of the flat anti-rotation portions. The front mass <NUM> is made of aluminium, although any other suitable metal could also be used. Although flat portions have been used as anti-rotation portions, it will be appreciated that other anti-rotation means could be used. For example, the transducer flange may comprise a plurality of spaced apart grooves <NUM>, as shown in <FIG> which may be configured to interact with a plurality of spaced apart protrusions. The grooves and protrusion may interact so that the transducer is prevented from rotating.

The back mass <NUM> is a hollow cylinder which is configured to dampen the ultrasound energy propagating toward it, resulting in large vibrations at the front mass. The back mass <NUM> is made of steel, although any other suitable metal could be used.

Positioned between the front and back masses is a plurality of piezoelectric rings <NUM>. As can be seen in <FIG>, two piezoelectric rings <NUM> are stacked between the front <NUM> and back <NUM> masses. The piezoelectric rings <NUM> are made from a high Q piezoelectric material for example Navy Type I (PZT <NUM>) or Navy Type III (PZT <NUM>), which are lead based piezo ceramic materials. Lead based piezo ceramics are used for low frequency, high power applications due to their lower losses and high coupling coefficient. However, the piezoelectric rings could be made from any other suitable material instead. For example, they could be made using lead-free piezo ceramics.

On each side of the piezoelectric ring <NUM> there is an electrode to allow for an electrical wire connection. The electrodes are brass, however any other suitable metal could be used. The two electrodes are <NUM>° to each other and are positioned perpendicular to the anti-rotation features on the flange. This allows for easy assembly of the transducer <NUM> in its housing <NUM>.

The transducer <NUM> further comprises a bolt <NUM>, as shown in <FIG>. The bolt <NUM> passes through the back mass <NUM>, the stack of piezoelectric rings <NUM>, and terminates in the front mass <NUM>. The transducer also comprises an alumina insulator (not shown) for patient safety. The bolt <NUM> is a pre-stress bolt and is configured to keep the transducer assembly intact and under compression at all times to avoid the generation of cracks in the piezoelectric material during the high drive cycle. The bolt <NUM> is made from stainless steel, although any other suitable material could also be used. The head <NUM> of the bolt is hex-shaped, however any other suitable shape could be used.

Referring to <FIG>, the transducer housing <NUM> is used to connect the transducer to the needle housing <NUM> and the ultrasound generator <NUM>. The transducer housing <NUM> comprises a front section <NUM>, a main body section <NUM>, and an end cap <NUM>. The front section <NUM> of the transducer housing is connected to the end cap <NUM> of the needle housing and the main body section <NUM> of the transducer housing. The main body <NUM> of the transducer housing contains the transducer <NUM> and is connected between the front section <NUM> and end cap <NUM>. The end cap <NUM> is used to connect the transducer <NUM> to the ultrasound generator unit <NUM>.

The front section <NUM> of the transducer housing is shown in <FIG> and is a generally cylindrical component. The front section <NUM> is hollow, so that there is a passage <NUM> passing through the front section <NUM>. The external surface of the front section is threaded <NUM> to allow the front section <NUM> to be connected to other components. The screw thread 144a at one end of the front section corresponds to the internal screw thread <NUM> on the end cap <NUM> of the needle housing so that these two parts can be screwed together for releasable attachment to each other. The screw thread 144b at the other end of the front section <NUM> corresponds to a thread of the main body <NUM> of the transducer housing so that these two parts can be screwed together for releasable attachment to each other.

In some embodiments, instead of being externally threaded, the front section <NUM> can be clipped into the main body <NUM> of the transducer housing and the end cap of the needle housing. For example, snap-fit connections may be present on the front section, main body of the transducer housing and the end cap of the needle housing. Other suitable connection means may also be used, for example a bayonet connection.

The front section <NUM> comprises a flange <NUM> which extends radially from the outer surface of the front section <NUM>. The flange <NUM> is positioned approximately half way along the length of the front section <NUM>, dividing the external threaded portion <NUM> into two separate sections 144a, 144b. The flange <NUM> prevents the front section <NUM> from being screwed too far into its connecting parts. It is therefore not possible to screw the front section <NUM> too far into either the main body <NUM> of the transducer housing or too far into the end cap <NUM> of the needle housing <NUM>.

The external surface of the front section <NUM> further comprises first and second flat portions <NUM>, as shown in <FIG>. These portions are spanner flats which allow the front section <NUM> to be tightly screwed into its neighbouring components through the use of a spanner. The two flat sections <NUM> are positioned substantially opposite each other radially and at both ends of the front section <NUM>. Embodiments in which the front section <NUM> does not screw into the main body of the transducer housing <NUM> may not have the flat sections present as they are not needed.

The front section <NUM> is formed from a single component by injection moulding, although any other suitable manufacturing process could also be used. The front section <NUM> is plastic, although any other suitable material could be used.

The main body <NUM> of the transducer housing is generally cylindrical in shape, as can be seen in <FIG>. The main body <NUM> is hollow so that there is a passage <NUM> extending through the main body <NUM> between two ends <NUM>, <NUM> of the main body. The diameter of the main body at one end <NUM> is slightly larger than the diameter of the main body at the opposite end <NUM>. This means that the main body <NUM> is slightly tapered from one end to the other end, giving it a slightly conical shape. The internal surface of the slightly larger end <NUM> is internally threaded <NUM> so that the main body <NUM> can be connected to a neighbouring component. The internal thread <NUM> corresponds to the externally threaded portion <NUM> of the front section <NUM> of the transducer housing <NUM> so that these two components can be screwed together.

The external surface of the smaller end of the main body comprises a plurality of spaced apart grooves <NUM>. The grooves extend longitudinally from the small end <NUM> of the main body <NUM> to approximately half way down the length of the main body <NUM>. The grooves <NUM> are positioned around the entire circumference of the small end <NUM>, as can be seen in <FIG>. The grooves <NUM> provide a grippable surface to help the user grip the main body <NUM> of the transducer housing. It will be appreciated that any other suitable pattern for providing grip can be used, for example a plurality of raised ridges instead of grooves, or a plurality of spaced apart bumps.

At the small end <NUM> of the main body are holes <NUM> for receiving screws <NUM>. Two holes <NUM> are provided, although any other suitable number of screw holes could also be used. The screw holes <NUM> are equally spaced about the circumference of the small end <NUM> of the main body <NUM>. As can be seen in <FIG> the two holes <NUM> are positioned substantially opposite each other. The screw holes <NUM> are used to connect the end cap <NUM> of the transducer housing <NUM> to the main body <NUM> of the transducer housing <NUM>.

Inside the main body <NUM> of the housing is an internal, radially extending flange <NUM>. The internal flange <NUM> is located part way along the length of the main body <NUM>, towards the large end <NUM> of the main body <NUM>. The flange <NUM> comprises a plurality of support slots <NUM> to help support the transducer <NUM> inside the transducer housing <NUM>. The flange further comprises anti-rotation pins <NUM> which are configured to correspond to the anti-rotation grooves <NUM> in the transducer. The structure of the flange can be more clearly seen in <FIG>.

The main body <NUM> of the transducer housing <NUM> is a single component formed via injection moulding, although any other suitable manufacturing process could also be used. The main body <NUM> is made from plastic, although any other suitable material could also be used.

The end cap <NUM> of the transducer housing is shown in <FIG>. The end cap <NUM> is generally cylindrical in shape, having a first end <NUM> and a second end <NUM>. A hollow passage <NUM> is provided which extends through the end cap <NUM> between the two ends <NUM>, <NUM>.

The first end <NUM> of the end cap comprises holes <NUM> for receiving screws <NUM>. Two holes <NUM> are provided, although any other suitable number of screw holes could also be used. The number of screw holes <NUM> present on the end cap <NUM> is the same as the number of screw holes <NUM> provided on the small end <NUM> of the main body <NUM> of the housing. The screw holes <NUM> are equally spaced about the circumference of the end cap <NUM>. As can be seen in <FIG> the two holes <NUM> are positioned substantially opposite each other. The screw holes <NUM> on the end cap <NUM> are configured to line up with the screw holes <NUM> on the main body <NUM> of the transducer housing so that these two components can be connected together using screws <NUM>.

The second end <NUM> of the cap comprises a flange <NUM>. The flange <NUM> extends radially away from the end cap <NUM>. The flange <NUM> has an outer perimeter which comprises a plurality of grooves <NUM>. The grooved pattern <NUM> on the perimeter of the end cap <NUM> is configured to correspond to the grooved pattern <NUM> on the small end <NUM> of the main body <NUM> of the transducer housing <NUM>. Thus, when the end cap <NUM> has been connected to the main body <NUM>, the grooved patterns <NUM>, <NUM> on the two components will align.

As mentioned previously, the ultrasound generator unit <NUM>, or control box <NUM>, vibrates the needle <NUM>. Referring to <FIG>, the control box <NUM>, or generator unit <NUM>, is substantially box shaped. The control box <NUM> comprises a sloping control panel <NUM>. That is, the control box <NUM> has a front face <NUM> that is slanted backwards, so that a top edge of the front face <NUM> is tilted towards a rear face <NUM> of the control box <NUM>. However, as will be understood, in other embodiments the front face <NUM> may not be sloping. The front face <NUM> comprises an amplitude control dial <NUM>. The control dial <NUM> comprises an embedded LED <NUM>, which is used to indicate whether or not the ultrasound is on. The front face <NUM> also includes a plurality of other LEDs <NUM> which are used to indicate the status of the generator unit <NUM>. For example, the LEDs <NUM> may be used to indicate whether the power is on or whether there is a fault. Additionally, the front face <NUM> comprises a transducer connector <NUM>. This is used to connect the transducer <NUM> to the control box <NUM>.

Referring to <FIG>, the rear face <NUM> of the control box <NUM> comprises a plurality of switches and connectors including a power supply connector and a foot switch connector. There may also be a rocker switch present. The foot switch connector is used to connect the foot switch <NUM> to the control box <NUM>.

The generator unit <NUM> is a dedicated adaptable derive electronic control box which is able to track the frequency and vibrational amplitude of the needle. The generator unit <NUM> is used to vibrate the needle <NUM> at its resonant frequency. The generator unit <NUM>, or control unit <NUM>, monitors changes in transducer drive frequency and electrical impedance and adapts to the changing conditions in real time. This is done by tuning the drive function accordingly so that the vibration amplitude is maintained at all times.

The control dial <NUM>, or power regulator dial <NUM>, allows the user to control the power, or vibration amplitude, according to the user's requirements. For example the user may wish to reduce the force or increase visibility. The provision of a foot switch connection allows the user to activate the ultrasonics with the press of the pedal <NUM>.

A standard foot pedal activation switch <NUM> is connected to the control unit <NUM>, or ultrasound generator unit <NUM>, to allow the user to activate the generator unit <NUM> as and when is needed. The foot switch <NUM> is connected to the control unit <NUM> using a standard USB connection as shown in <FIG>, although any other suitable connection can also be used. The control unit <NUM>, once switched on, will be on standby mode until the foot pedal switch <NUM> is pressed. The needle device <NUM> will be operational continuously for <NUM> minutes after which the power generator unit <NUM> will automatically switch to standby mode.

As already mentioned, the generator unit <NUM> uses ultrasound energy to vibrate the stylet <NUM> of the needle device <NUM>. Typically, the stylet <NUM> is vibrated at a frequency of between <NUM> - <NUM>, such as <NUM> - <NUM> or <NUM> - <NUM> with an amplitude ≤ <NUM>. The stylet <NUM> of the needle <NUM> vibrates in a longitudinal, or length-wise, direction. This reduces the penetration force require to insert the needle <NUM> into the tissue and so the needle's <NUM> journey into the target is smoother. Thus, the use of longitudinal vibration provide improved cutting of the tissue. The needle-transducer connection therefore plays an important role in ensuring efficient energy transfer from the ultrasound transducer <NUM> to the needle <NUM>. The stylet <NUM> is connected to the transducer <NUM> using a stylet hub <NUM>, or transducer adapter <NUM>.

Referring to <FIG>, the stylet hub <NUM> comprises a hexagonally shaped base portion <NUM> and an extending threaded portion <NUM>. The stylet <NUM> is attached to the hub <NUM> on one side of the base portion <NUM>. The base portion has a hole extending through the base portion, partly into the extended threaded portion <NUM>, as shown in <FIG>. The stylet <NUM> is inserted into the hole before being attached to the base of the hub <NUM>. Once one end of the stylet has been fully inserted into the hole, the stylet <NUM> is attached to the base <NUM> of the stylet hub <NUM> via a brazed joint. However, any other suitable join may be used, for example the stylet <NUM> could be laser welded to the base of the hub <NUM>. Inserting the stylet into the hole before the joining process provides a more secure connection between the stylet and the hub.

The extending threaded portion <NUM> is substantially opposite the stylet joint, as shown in <FIG>. The extending threaded portion <NUM> is configured to be attached to the front end <NUM> of the transducer <NUM> by screwing the stylet hub <NUM> into the transducer <NUM>.

A locking nut <NUM> may be provided to help the user connect the stylet <NUM> to the transducer <NUM>. The locking nut <NUM> is substantially cylindrical in shape, as shown in <FIG>. Inside the cylinder is a hex-shaped socket <NUM> which extends throughout the length of the locking nut <NUM>, as shown in <FIG>. The hex-shaped socket <NUM> is configured to correspond to the base portion <NUM> of the stylet hub <NUM> so that the socket <NUM> can be fitted around the base of the stylet hub <NUM>.

The external surface of the locking nut <NUM> is covered in a grippable outer surface <NUM>. The grippable outer surface <NUM> comprises a plurality of equally spaced apart longitudinal grooves <NUM> and projections <NUM>. The grippable outer surface <NUM> helps the user to screw the needle <NUM> into the transducer's front section <NUM>.

Referring to <FIG>, a longitudinal slot <NUM> extends along the entire length of the locking nut <NUM>, passing through the outer surface of the locking nut <NUM> and the hex socket <NUM>. The slot <NUM> allows the locking nut <NUM> to be positioned around the needle <NUM> to surround the needle <NUM> during the attachment process and then removed once the needle <NUM> has been attached to the transducer <NUM>. Although a hex-shaped hub <NUM> and socket <NUM> has been described, it will be appreciated that any other suitable shape could be used.

<FIG> illustrates how to connect the needle <NUM> to the needle housing <NUM>. Firstly, the cannula <NUM> is connected to the trigger lever <NUM>, as shown in <FIG>. This can be done using epoxy, or any other suitable material. The trigger lever <NUM>, trigger button <NUM>, and primary <NUM> and secondary springs <NUM> are then placed inside the first shell <NUM> of the main body <NUM> of the housing, as shown in <FIG>. The second shell <NUM> of the main housing body <NUM> can then be joined to the first shell <NUM> using an ultrasonic weld, as shown in <FIG>.

The second spring support <NUM> is then inserted into the housing cap <NUM>. The housing cap <NUM> and spring support <NUM> can then be connected to the main body <NUM> of the housing by inserting the spring support <NUM> through the free end of the primary spring <NUM> and joining the cap <NUM> to the main body <NUM> of the housing using ultrasonic welding, as shown in <FIG>.

The stylet <NUM>, attached to the stylet hub <NUM>, is then inserted through the housing cap <NUM> and spring support <NUM>, through the primary spring <NUM> in the needle housing <NUM>, through the trigger level <NUM> and cannula <NUM>, and extends out through the front end <NUM> of the needle housing, as shown in <FIG>.

A needle cover can then be slid over the needle <NUM>, including the cannula <NUM> and stylet <NUM>, to protect the needle <NUM> when the device <NUM> is not being used, as shown in <FIG>.

The locking nut <NUM> can then be attached, as shown in <FIG>. To attach the locking nut <NUM>, the stylet hub <NUM> is pulled back through the end cap <NUM> until the needle <NUM> can pass through the slot <NUM> in the locking nut <NUM>. The hexagonal base <NUM> of the stylet hub <NUM> rests inside the hexagonal socket <NUM> of the locking nut <NUM> while the threaded portion <NUM> of the stylet hub <NUM> extends from the locking nut <NUM>, as can be seen in <FIG>.

<FIG> illustrates how to connect the transducer <NUM> to the transducer housing <NUM>. Firstly a back spacer <NUM> is inserted into the large end <NUM> of the main body <NUM> of the transducer housing until the back spacer <NUM> abuts the flange <NUM>, as shown in <FIG>. The flange <NUM> comprises anti-rotation pins <NUM> which correspond with anti-rotation slots <NUM> on the back spacer <NUM>. The anti-rotation pins <NUM> are inserted into the anti-rotation slots <NUM>. The back space <NUM> comprises a groove for an O-ring <NUM>. An O-ring <NUM> is then inserted into the large end <NUM> of the transducer main body until it fits snugly into the O-ring groove, as shown in <FIG>. The O-ring <NUM> ensures that the transducer <NUM> is sealed tightly in the housing <NUM>.

A coaxial cable <NUM>, attached to the transducer <NUM>, is then passed through the flange <NUM> and main body <NUM> of the transducer housing so that the transducer <NUM> rests on the O-ring <NUM> inside the housing <NUM>, as shown in <FIG>. The coaxial cable <NUM> extends from the small end <NUM> of the transducer housing <NUM>. The transducer housing cap <NUM> is then inserted over the coaxial cable <NUM> to abut the main body <NUM> of the housing, as shown in <FIG>.

A second O-ring <NUM> is then inserted into the large end <NUM> of the transducer housing <NUM> so that the flange <NUM> of the transducer <NUM> is sandwiched between the two O-rings <NUM>, <NUM>, as shown in <FIG>. A front spacer <NUM> is then inserted into the large end <NUM> of the housing <NUM>, abutting the second O-ring <NUM>, as shown in <FIG>.

The spacers <NUM>, <NUM> ensure that the transducer <NUM> is positioned in the required axial position. The integrated anti-rotational features in the spacers help prevent rotation of the transducer <NUM> within the transducer housing <NUM>. The integration of the spacers within the housing permits flexibility in the design of the transducer, allowing the housing to accommodate revised transducers that may be required for difference needle gauges and lengths.

The front section <NUM> of the transducer housing <NUM> is then screwed into the large end <NUM> of the transducer housing body <NUM>. The front section <NUM> is screwed tight enough that the transducer <NUM> is properly secured inside the housing <NUM>, as shown in <FIG>.

Once the transducer <NUM> is secured in place, the end cap <NUM> of the transducer housing <NUM> is secured to the main transducer body <NUM> using screws <NUM>, as shown in <FIG>. The screws <NUM> are inserted into the screw holes in the end cap and main body of the housing. The screws <NUM> are self-tapping screws.

Once the needle housing parts and transducer housing parts have been assembled, the needle housing <NUM> is connected to the transducer housing <NUM>. This is illustrated in <FIG>.

Firstly, the front end <NUM> of the transducer housing is aligned with the rear end of the needle housing <NUM>, as shown in <FIG>. The stylet hub <NUM> is then screwed into the front mass <NUM> of the transducer <NUM> while the needle housing <NUM> and locking nut <NUM> are held together, as shown in <FIG>.

Once the stylet <NUM> is attached to the transducer <NUM>, the locking nut <NUM> is removed from between the transducer and needle housings <NUM>, <NUM>, as shown in <FIG>. The front section <NUM> of the transducer housing is then screwed into the end cap <NUM> of the needle housing, attaching the two housings together, as shown in <FIG>.

The coaxial cable <NUM> is then connected to the ultrasound generator unit <NUM> and the desired power level, or vibration amplitude, is pre-set. The device <NUM> is then activated by pressing on the foot switch <NUM>.

The needle <NUM> of the device <NUM> is generally only used once, for hygiene reasons, but the transducer <NUM> can be reused. Thus the needle device <NUM> comprises a single use part, comprising the needle housing <NUM>, and a reusable part, comprising the transducer housing <NUM>, generator unit <NUM>, and foot switch <NUM>. The reusable part therefore connects to the single use part via a screw mechanism. The locking nut <NUM>, or collar <NUM>, may be an intermediate part which facilitates connection of the single use part with the reusable part. However, the single use part may be connected to the reusable part without the need for a locking nut or collar.

In order for the transducer housing part to be reusable, it should be protected from the single use part using, for example, a sterile protective sheath <NUM>. <FIG> illustrates how the protective sheath <NUM> can be used. Firstly, the transducer assembly, including the transducer housing <NUM> and coaxial cable <NUM>, are wiped using an alcohol wipe, as shown in <FIG>. The transducer housing <NUM> is then placed inside a sterile protective sheath <NUM>, or sleeve <NUM>, as shown in <FIG>. The needle housing <NUM> is then aligned with the covered transducer housing <NUM>, as shown in <FIG>. While the needle housing <NUM> and locking nut <NUM> are held together, the stylet hub <NUM> is screwed tightly through the protective sheath <NUM> and onto the transducer <NUM>, as shown in <FIG>. The act of screwing the stylet <NUM> onto the transducer <NUM> pierces the protective sheath <NUM>. Once the stylet <NUM> is attached, the locking nut <NUM> is removed, as shown in <FIG>. The transducer housing <NUM> is then screwed onto the needle housing <NUM>, trapping the protective sheath <NUM> between the two housings, as shown in <FIG>. The free end of the protective sheath <NUM>, or sleeve <NUM>, can be fixed to the coaxial cable <NUM> using an elastic band so that the free end does not get in the way of the user.

Once the device <NUM> has been connected together, it can be used to carry out an ultrasound-guided needle biopsy. An ultrasound probe, not part of and separate to the needle device <NUM>, is used to create an ultrasound image of a region of tissue to be sample. Ultrasonically actuated needles have increased visibility in certain types of medical imaging, such as ultrasound imaging. An oscillating biopsy needle is therefore highly visible under ultrasound and so the location of the needle, in particular the needle tip, can be accurately known.

In addition, vibrating the needle longitudinally at ultrasonic frequencies reduces the penetration force required to introduce the needle <NUM>, namely the stylet <NUM>, into the tissue sample. Thus, the amount by which the needle <NUM>, or stylet <NUM>, deflects upon entry is also reduced.

To vibrate the stylet <NUM> of the needle <NUM>, the signal generator <NUM> applies a drive voltage to the piezoelectric rings <NUM> inside the transducer <NUM>. The amplitude and/or frequency of the drive voltage can be manually adjusted by the user, using the control panel <NUM> on the generator <NUM>, so the motion of the stylet <NUM> can be adjusted. The drive voltage applied to the piezoelectric rings <NUM> causes the piezoelectric rings <NUM> to be actuated.

Actuation of the piezoelectric rings <NUM> in the transducer <NUM> causes reciprocating motion between the front <NUM> and back <NUM> masses of the transducer <NUM>. Thus, the relative positions of the front <NUM> and back <NUM> masses changes which cause the front mass <NUM> to move along a longitudinal axis relative to the back mass <NUM>. As the stylet <NUM> of the needle <NUM> is connected to the front mass <NUM> of the transducer <NUM>, via the stylet hub <NUM>, any motion of the front mass <NUM> is transferred to the stylet. The piezoelectric rings <NUM> therefore cause the stylet <NUM> to reciprocate along the longitudinal axis of the needle <NUM>. In other words, the needle <NUM> is caused to vibrate, by actuating the piezoelectric rings <NUM> in the transducer <NUM>, with a reciprocating motion along its central longitudinal axis. Only the stylet <NUM> of the needle <NUM> is caused to vibrate; the cannula <NUM> of the needle <NUM> remains stationary relative to the stylet <NUM>. This is because only the stylet <NUM> is connected to the transducer <NUM>, via the stylet hub; the cannula <NUM> is not connected to the transducer <NUM>.

The signal generator can be adjusted to tune the resonant frequency of the piezoelectric rings <NUM> so that the needle device <NUM> is optimised for different types of needle stylet <NUM>.

Once the needle <NUM> is vibrating at the correct frequency and amplitude, the needle <NUM> is inserted into the tissue. The trigger <NUM> is then pulled back, withdrawing the cannula <NUM> and exposing the sample notch <NUM>. The trigger <NUM> is then released, releasing the cannula <NUM>, to take the biopsy. The needle <NUM>, and its enclosed tissue sample, can then be removed from the body.

Although the needle device <NUM> has been described using a stylet hub <NUM> that screws into the transducer <NUM>, other stylet hubs could be used. In some embodiments a gripping device is used to connect the needle to the transducer. An example of a commonly used gripping device includes a collet. A problem with using a gripping device to secure the needle to the transducer is that it is easy to over-tighten or under-tighten the gripping device. If the gripping device is too tight, it may crush the needle. The risk of crushing the needle is especially high if the needle is a hollow needle. If the gripping device is not tight enough then the needle will be loosely connected to the transducer. This may result in inefficient energy transfer between the transducer and the needle. In addition, using a gripping device such as a collet only provides a small point of contact between the needle and transducer. This means that a secure, stable connection is hard to achieve.

In other embodiments, other stylet hubs could be used which avoid the problems associated with the collet style of join. For example, in some embodiments, the stylet hub <NUM> could be connected to the transducer <NUM> using a bayonet style connection. In some embodiments a snap-fit connection could be used. Any mechanism which has a large, secure point of contact between the needle and transducer but which does not rely on the provision of compression, or a gripping mechanism, to secure the needle <NUM> to the transducer <NUM> would be suitable for use with the needle device <NUM> described herein.

In still further embodiments, the needle can be connected to the transducer using a connection member <NUM>, as shown in <FIG>. The connection member is an external clip <NUM>. The clip comprises two curved arms <NUM>, <NUM>, spaced apart from each other. The arms <NUM>, <NUM> are connected together by external ribs <NUM>, as shown in <FIG>. One of the arms <NUM> is configured to be clipped around the external surface of the transducer while the other arm <NUM> is configured to be clipped around the external surface of the needle. Thus, the clip <NUM> is configured to maintain the connection between the needle and the transducer.

Although the needle <NUM> has been described as being single use, in other embodiments the needle <NUM> can be reused.

Although the vibrating probe has been described with reference to a solid needle, in other embodiments the probe is hollow needle. The hollow needle is used to deliver fluid to body tissues.

<FIG> shows an example of a vibrating probe device comprising a hollow needle <NUM>. As before, the needle <NUM> is connected to one end of the transducer <NUM> using a hub <NUM>. At the other end of the transducer <NUM> is a syringe <NUM>. The syringe <NUM> is connected to the needle <NUM> using a hollow tube <NUM>. Thus, the tube <NUM> passes through the centre of the transducer <NUM>.

As before, the transducer <NUM> is connected to a signal generator (not shown) which allows the transducer to vibrate the needle <NUM> longitudinally at ultrasonic frequencies. This reduces the penetration force required to insert the needle <NUM> into the tissue. Deflection of the needle tip <NUM> upon entry is also reduced. The syringe <NUM>, after being filled with fluid, is activated by the user so that fluid can be injected into the body.

In order to allow fluid to pass from the syringe <NUM> at one end of the transducer <NUM> to the needle <NUM> at the other end of the transducer <NUM>, the transducer <NUM> is provided with a channel <NUM>. The channel <NUM> extends along the entire length of the transducer <NUM>, as can be seen in <FIG>. As well as passing through the main body of the transducer <NUM>, the channel <NUM> also extends through the pre-stress bolt <NUM>.

In order to provide a sterile environment in which fluid may flow, the hollow tube <NUM> is inserted into the channel <NUM> of the transducer <NUM> before the device is used. The hollow tube is a sterile tube having closed ends at both ends of the tube <NUM>, as shown in <FIG>. This ensures that the inside of the tube <NUM> remains sealed against potential contaminants when the device is not being used. The closed ends of the sterile tube <NUM> are penetrated by the syringe <NUM> and hub <NUM> when the syringe <NUM> and needle <NUM> are connected to the transducer. The device is then ready to be used for fluid injection.

As discussed previously, the pre-stress bolt is needed to maintain tension between the piezoelectric components as well as the front and back masses. Drilling a hole through the bolt <NUM> to allow the passage of fluid therefore makes the bolt mechanically weak.

An alternative approach is to provide a transducer <NUM> having two pre-stress bolts <NUM>, <NUM>, one on either side of the transducer <NUM>, as shown in <FIG>. Each bolt extends longitudinally along a portion of the external surface of the transducer <NUM>. The bolts <NUM>, <NUM> are spaced apart from each other around the outer perimeter of the transducer <NUM>. As can be seen from <FIG>, the two bolts are spaced substantially <NUM>° apart from each other.

The bolts are connected to the transducer using two bracer portions <NUM>, <NUM>. The bracer portions <NUM>, <NUM> are perpendicular to the main body of the transducer <NUM>. The transducer <NUM> is then provided with a fluid channel <NUM> passing through the middle of the transducer <NUM>. As before, a hollow tube <NUM> is inserted into the channel <NUM> before use and a hollow needle and syringe are connected to either end of the tube <NUM>. The device is then ready to be used to inject fluid into tissue.

<FIG> shows an alternative embodiment of a needle housing. The main body <NUM> has a pair of rails <NUM> provided on either side on the slots <NUM> which receive the trigger lever. The rails <NUM> allow the trigger lever to slide over the needle housing without any lateral motion, or wobble.

<FIG> shows an alternative embodiment of a back spacer. The anti-rotation pins have been replaced with anti-rotation flats <NUM>.

In some embodiments the catch comprises a barb angle on the flat surface of the catch on both the needle housing and the trigger lever. The engaging surface of the catch and trigger lever may also be rough surface to provide increased friction between the surfaces.

In some embodiments the secondary needle spring positioned around the trigger button may be omitted. In this case, before the trigger has been cocked, the flange of the trigger button will rest the bottom surface of the trigger button slot. When the trigger lever has been cocked, ready for triggering, the engaging surfaces of the trigger button and trigger lever will come into contact with each other. The trigger lever will push up slightly on the trigger button so that the trigger button is raised slightly and protrudes from the trigger button slot, informing the user that the lever has been latched and is ready to be used.

In use, the clinician advances the needle through skin and layers of tissue under ultrasound guidance. Suitably, B-mode (or 2D mode) ultrasound is employed in this context. In B-mode (brightness mode) ultrasound, a linear array of transducers simultaneously scans a plane through the body that can be viewed as a two-dimensional image on screen. The ultrasound beam is fan-shaped, and is positioned over the needle and visualized on the screen. The clinician advances the needle to the target.

The device either has the stylet extended on reaching the target, or it is extended from the cannula on arrival in the location. This is suitably achieved by cocking the device as described above. Sampling occurs when the clinician fires the device and a spring rapidly pushes the outer cannula over the stylet, thereby collection tissue.

The needle is then withdrawn from the patient. Repeating the cocking action of the device reveals a sample of tissue in the sample notch. The sample is then suitably sent for analysis, e.g. pathology.

The device of the invention finds use in a wide variety of clinical procedures. These include, but are not limited to the following:
Amniocentesis - this is a procedure utilized to obtain a sample of amniotic fluid from a pregnant woman's uterus for diagnostic purposes. Such fluid is obtained, by inserting a long spinal needle, having a sharp-cutting tip, through the skin, fascia and uterine muscle into the uterine cavity and obtaining therefrom such amniotic fluid by aspiration. Complications, including trauma, haemorrhage and infection have resulted from employing such prior-art surgical needle in such procedure. The device of the invention, being capable of accurate guidance under ultrasound imaging (a non-invasive imaging technique known to be safe to unborn infants) is advantageous compared to known devices and methods.

Chorionic villus sampling - chorionic villi are finger-like projections of tissue in the chorionic membrane which eventually forms the placenta. Chorionic villi are well developed around the seventh to eighth weeks of pregnancy. The object of this procedure is to remove, by vacuum, a sample of the villi and assay the sample to determine the genetic health of the fetus. A physician inserts a thin catheter (consisting of a cannula containing an obturator) through the vagina and cervix into the uterus ending at the chorion membrane. When the catheter tip is located on the villi, a source of negative pressure is coupled to the catheter to withdraw a sample of villi tissue for analysis. The device of the invention, being capable of accurate guidance under ultrasound imaging (a non-invasive imaging technique known to be safe to unborn infants) is advantageous compared to known devices and methods.

Vacuum-assisted biopsy - through a small incision or cut in the skin, a biopsy needle is inserted into e.g. the breast and, using a vacuum-powered instrument, several tissue samples are taken. The vacuum draws tissue into the centre of the needle and a rotating cutting device takes the samples. The samples are retrieved from the centre of the biopsy needle following the procedure and sent to a laboratory to be examined by a pathologist (a specialist doctor trained in diagnosing biopsies).

The biopsy procedure is performed under imaging guidance (mammogram, magnetic resonance imaging (MRI) or ultrasound). In other words, the pictures or images obtained from scans allow the radiologist performing the biopsy to make sure the needle is correctly positioned. The devices of some embodiments of the invention are advantageous in vacuum-assisted biopsy procedures. Similarly, the devices of the invention are useful in vacuum-assisted excision of tumours (ultrasound-guided vacuum excision, or UGVAE).

In vitro fertilization (IVF) - in such procedures, eggs are usually retrieved from the patient by transvaginal oocyte retrieval involving an ultrasound-guided needle piercing the vaginal wall to reach the ovaries. Through this needle, follicles can be aspirated, and the follicular fluid is handed to the IVF laboratory to identify and diagnose the ova. The fertilized egg, (embryo), or usually multiple embryos, are then transferred to the patient's uterus with the intention of establishing a successful pregnancy. The devices of some embodiments of the invention are advantageous in IVF methods, both for egg retrieval and embryo implantation.

Localized drug delivery - frequently, it is desirable to infuse solutions of medicaments to a particular region or organ of the body. Such medicaments include anaesthetics (e.g. for local anaesthesia), particles for embolization (embolotherapy), and nanoparticles. The devices of the invention are useful in this context, as they allow delivery of medicaments to precise locations under ultrasound guidance. In particular, it is advantageous to use the devices of the invention as the action of the needle may improve distribution of drug/liquids or colloids.

Fine-needle aspiration (FNA) - a diagnostic procedure used to investigate lumps or masses. In this technique, a thin, hollow needle is inserted into the mass for sampling of cells that, after being stained, will be examined under a microscope (biopsy). The sampling and biopsy considered together are called fine-needle aspiration biopsy (FNAB) or fine-needle aspiration cytology (FNAC). The ability of the clinician to guide a needle tip to the desired sampling locality under ultrasound guidance provided by the devices of the present invention makes these advantageous in fine-needle aspiration. It is believed that the action of the needle helps to dislodge cells from the target and improve sampling.

Radiofrequency ablation (RFA) - a medical procedure in which part of the electrical conduction system of the heart, tumour or other dysfunctional tissue is ablated using the heat generated from medium frequency alternating current (in the range of <NUM>-<NUM>). RFA is generally conducted in the outpatient setting, using either local anaesthetics or conscious sedation anaesthesia. When it is delivered via catheter, it is called radiofrequency catheter ablation. Clearly, it is very desirable in such procedures that the ablation probe is correctly located proximal to the dysfunctional tissue; the devices of the present invention makes these advantageous in such techniques.

Claim 1:
A device (<NUM>) for use in a medical procedure, the device comprising:
an elongate member having a first end, a second end, and a longitudinal axis extending between said ends, said first end being a sharps end, and said second end comprising an integral hub;
an ultrasonic transducer (<NUM>) comprising a socket adapted to receive said hub;
characterised by the transducer (<NUM>) being configured to oscillate the elongate member substantially along the longitudinal axis at a frequency of above <NUM>; and
wherein the maximum amplitude of oscillation is limited to ≤<NUM>.