Fine-needle aspiration cell sampling methods

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BACKGROUND OF THE INVENTION

The present invention relates to methods and apparatus for taking samples of cells from discrete tissue areas. The taking of such samples is necessary in the cytological diagnosis of suspect tissue areas such as tumors.

Various techniques have been used to take cells from tumors in order to establish whether they are benign or malignant. The choice of a specific technique depends on several factors, including the location and size of the area to be sampled, the susceptibility of the area to complications such as infection, and the ease of use.

One commonly used technique is the so-called core needle biopsy technique wherein a relatively large hollow needle (e.g., 14 gauge) is forced into the tissue to be sampled and then retracted to yield a core sample suitable for histological evaluation. The taking of core needle biopsy specimens is particularly prevalent in the diagnosis of prostatic cancer in the United States. The popularity of this technique is attributed in part to the minimal training required to perform the procedure. In fact, it not infrequently results in complications due to the inevitable traumatization of the tissue by the relatively large needle.

An alternative to the core needle biopsy technique is the so-called fine-needle aspiration technique. Cytological diagnosis with the aid of fine-needle puncture and aspiration started in the late 1950's, when it was shown that individual cells collected from tumors by means of this technique could be recognized and classified. The fine needle aspiration technique offers numerous advantages over core needle biopsy. For example, with respect to the cytological diagnosis of prostatic cancer, fine needle aspiration can be performed as an outpatient procedure without anesthesia or bowel preparation. Further, the patient can be informed of the diagnosis almost immediately and there is an extremely low incidence of complications (1% in 14,000 cases). Moreover, aspiration cytology has proven to be more accurate in prostate cancer diagnosis than conventional core needle histological biopsy. In summary, fine needle aspiration biopsy is an accurate, inexpensive and safe method of diagnosing cancer.

Current fine-needle aspiration apparatus and techniques, however, suffer from several disadvantages, which have contributed to limiting their widespread acceptance in the United States.

U.S. Pat. No. 3,595,217 discloses a method and apparatus for fine needle aspiration biopsy of the prostate. The method and apparatus disclosed in U.S. Pat. No. 3,595,217 are very similar to the method and apparatus commonly used throughout Europe and increasingly used in the United States. However, the disclosed method and apparatus are cumbersome to use, requiring, in practice, at least one highly trained person with an assistant to successfully perform the procedure since the needle is first inserted in the patient, and a syringe is thereafter attached while the operator's hand remains in the patient. Moreover, the disclosed method and apparatus do not readily lend themselves to the use of a stylet during penetration and withdrawal of the needle. Furthermore, the insertion, withdrawal and reciprocation of the needle during the procedure are not precisely determinable since the procedure is performed manually with no means to precisely monitor needle movement. In addition there is a lengthy learning curve that can only be overcome by performing many manual (conventional) fine-needle aspiration biopsies under proper instruction.

U.S. Pat. No. 4,605,011 to Naslund discloses yet another prior art attempt to solve the problems associated with fine-needle aspiration methods and apparatus. The Naslund cell sampling methods and apparatus, however, have several disadvantages. First, because a stylet is not used to occlude the tip of the needle during the aspiration procedure, there is a danger of patient and sample contamination. For example, in prostate aspiration, the absence of a stylet increases the risk of contamination of the aspirated sample and inoculation of the prostate with enteric bacteria present in the rectal vault when the needle is passed through the rectal mucosa into the suspected tumor in the prostrate gland. The Naslund apparatus and method further require that the tip of the biopsy needle be introduced into the suspected tumor without predictability or repeatability, because the operator is unable to precisely determine the forward excursion of the needle when penetrating the target area. Also, the persistence of vacuum in the needle and adjacent connecting tube of Naslund after release of the trigger at the conclusion of the biopsy could tend to cause (i) aspiration of contaminants or debris, such as rectal mucosa and/or bacteria residing in the rectum, and (ii) potential loss of sample into the connecting tube. Furthermore, Naslund employs a single gauge fine needle, thus limiting the total amount and recoverability of cell sample. Accordingly, the Naslund cell sampling apparatus is not well suited for certain applications, such as the cytological diagnosis of prostatic cancer.

Accordingly, it is an object of the present invention to provide an apparatus and method for fine-needle aspiration which simplify and standardize the fine-needle aspiration technique.

It is a further object of the present invention to provide a fine-needle aspiration apparatus and method which allow the needle to be occluded during the penetration and withdrawal stages of the procedure to avoid introducing contaminants into the sample or the region being biopsied.

It is a further object of the present invention to provide a fine-needle apparatus and method which enable a single person to perform the biopsy procedure.

Another object of the present invention is to provide a device capable of performing a fine-needle aspiration biopsy quickly and safely, preferably in an out-patient setting, such as the practitioner's office.

It is a further object of the present invention to provide a fine-needle apparatus and method which will standardize and simplify the aspiration procedure by automatically performing one or more steps of the aspiration procedure.

It is a further object of the present invention to provide a fine-needle aspiration cell sampling apparatus having a failsafe feature which automatically occludes the needle tip, and retracts the needle in emergency circumstances.

It is a further object of the present invention to provide a fine-needle biopsy apparatus which is entirely disposable or in which all parts subject to contamination are disposable.

It is another object of the present invention to provide a fine-needle aspiration apparatus and method which facilitate the collection of cytological samples without coring the tissue in the region being sampled.

It is also an object of the present invention to provide a fine-needle aspiration apparatus and method which facilitate the collection of a sufficient quantity of cells to enable an accurate cytological diagnosis to be made (i.e.. malignant vs. benign).

It is a further object of the present invention to provide apparatus and methods which simplify and facilitate the expression of cytological samples retrieved through fine-needle aspiration.

These and other objects will become apparent to those skilled in the art upon reviewing the summary of the invention, and the detailed description and drawings of the preferred embodiments of the invention hereinafter set forth.

SUMMARY OF THE INVENTION

The present invention relates to improvements in apparatus and methods for performing biopsies by fine-needle aspiration of cytological samples. In accordance with the method of the present invention, the operator performing the biopsy locates the sheath in the proximity of the biopsy target area. During this initial location stage, the sheath and needle are positioned with respect to each other such that the needle tip is obscured by the end of the sheath. In accordance with the method, the opening of the needle is occluded during this stage of the fine-needle aspiration procedure. Thereafter, the needle is moved forward with respect to the sheath, causing the occluded needle to enter the target area. Openings in the needle are then unoccluded and vacuum is applied to the needle. The needle is thereafter reciprocated, causing the cytological sample to be drawn into the needle. After a predetermined number of reciprocations (determined by the desired sample yield), the needle openings are again occluded, the vacuum is released and the needle is then withdrawn. Because the needle openings are occluded both during penetration and withdrawal, contaminants are not drawn into the needle. Moreover, occlusion of the needle openings during penetration minimizes the introduction of contaminants from the penetration path to the target area, thereby reducing the chance of infection in the target area.

Disclosed herein are several preferred fine-needle aspiration biopsy apparatus embodiments for performing the above-described method. Each of the preferred embodiments enable the biopsy procedures to be standardized, include mechanisms for occluding the needle during penetration and withdrawal, and renders feasible the performance of the biopsy by a single operator.

A first preferred embodiment of the invention is a fine-needle biopsy apparatus which automatically performs the above-discussed fine-needle aspiration method. In particular, the first embodiment comprises a gun having a syringe and needle. The needle protrudes from the gun and is surrounded by a sheath, which is removably secured to the gun. In operation, the sheath and needle are positioned next to the target area, and the operator initiates the automatic aspiration procedure by sequentially activating safety and trigger mechanisms. After activation, the first preferred embodiment of the present invention automatically initiates the method steps, including (1) penetration of the needle into the target area while the opening of the needle is occluded; (2) unoccluding the needle opening and applying vacuum to the needle; (3) reciprocating the unoccluded needle to collect the cytological sample; (4) again occluding the needle opening and releasing the vacuum; and (5) withdrawing the needle. After the cycle has been automatically completed and the cytological sample has been obtained, the sample is expressed onto a microscope slide by of one of several disclosed methods.

The gun of the first preferred embodiment utilizes a disposable assembly, comprised of a syringe, syringe plunger, variable diameter needle, stylet and sheath. The stylet is connected to the plunger, and is dimensioned such that it occludes the needle opening when the plunger is in its forwardmost position, but unoccludes the needle opening when the plunger is withdrawn. The disposable assembly is removed after operation, and the non-disposable portion of the apparatus (i.e., the gun) is ready for use without sterilization.

The first preferred embodiment is electromechanically operated via solenoids and a D.C. motor. However, D.C. stepping motors or servo motors can be utilized in lieu of one or more of the electromechanical solenoids and D.C. motor to actuate the apparatus. In a modification of the first embodiment, pneumatic cylinders and pistons can be used in lieu of the electromechanical devices for actuating the apparatus.

Numerous safety features are incorporated in the first preferred embodiment of the present invention, including a mechanism for ensuring retraction of the needle into the sheath upon release of the trigger by the operator. An alarm and safety breaker are provided to respectively inform the operator and disable the apparatus should a mechanical or electromechanical problem occur. Furthermore, the automatic apparatus will not operate if there is insufficient power to complete the entire aspiration cycle.

In further modifications of the first preferred embodiment, the syringe and plunger are not disposable, but instead are incorporated within the reusable portion of the apparatus. Only the needle, stylet and sheath are disposable. In this embodiment, the plunger incorporates a grabber mechanism, which is either mechanically or electrically actuated, to grab the stylet for movement with the plunger to, respectively, occlude and unocclude the needle openings.

In a second preferred embodiment of the present invention, the needle, stylet, sheath, and syringe arrangement of the first embodiment of the invention are manually operated in lieu of the automatic apparatus of the first preferred embodiment of the invention. As with the automatic apparatus, the stylet of the manual apparatus occludes the needle opening during the insertion and withdrawal stages of the procedure. A gage and stop are provided to enable the operator to monitor the movement of the needle during the procedure, facilitating standardization of the procedure. As with the automatic embodiment, the procedure can be performed by a single operator without the need for extensive training or experience. The entire apparatus can be disposable or, alternatively, the syringe, plunger, needle, stylet and sheath can be disposable and used with a reusable handle apparatus.

As will be appreciated from the foregoing discussion, the first and second embodiments of the present invention utilize a variable diameter needle and a stylet to selectively occlude the needle opening. Third and fourth preferred embodiments of the invention are also disclosed, in which the stylet is omitted, and the needle is instead occluded during insertion and withdrawal by an outer sleeve, which is retracted during the aspiration procedure to expose the needle openings and allow cytological sample to be drawn into the needle. The third embodiment is manually operated, and the fourth embodiment is automatic.

In each of the above-discussed embodiments, several alternative sheath designs can be implemented depending upon the type of biopsy to be performed. For trans-rectal biopsies of the prostate, a sheath having a finger guide and handle portion is used to facilitate manipulation by the operator. For biopsies of soft, fleshy tissue regions (e.g., the breast) a disc-like sheath end can be implemented to stabilize and locate the sheath and needle on the fleshy tissue. The sheath can also be designed to accommodate an ultrasonic transducer so that the target area can be ultrasonically probed to position the sheath and needle. Additionally, several alternative needle designs can be implemented to reduce coring by the needle and minimize needle fouling.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described with reference to the drawings wherein like reference numerals refer to similar parts throughout the several views and in which:

FIGS. 1a-1f re schematic cross-sectional views illustrating the method of the present invention;

FIG. 2 is a cross-sectional view of a needle and sheath assembly of the present invention;

FIG. 3 is a cross-sectional view of the needle and sheath assembly of FIG. 2 taken along line III--III

FIG. 4 is a cross-sectional view of the needle and sheath assembly of FIG. 2 taken along line IV--IV;

FIG. 5 is a cross-sectional view of the needle and sheath assembly of FIG. 2 taken along line V--V;

FIG. 6 is a cross-sectional view of the needle and sheath assembly of FIG. 2 taken along line VI--VI;

FIG. 7 is partial side cross-sectional view of the needle and sheath assembly of FIG. 2;

FIG. 8 is an enlarged cross-sectional view of the sheath and needle tip of the needle and sheath assembly of FIG. 2;

FIGS. 9a-9c are cross-sectional views of alternative needle and stylet arrangements:

FIGS. 10a and 10b are cross-sectional views of an alternative needle and sheath arrangement of the present invention;

FIG. 11 is a cross-sectional view of a further alternative needle and sheath arrangement of the present invention;

FIG. 12 is a cross-sectional view of a modification of the needle and sheath assembly of the present invention;

FIG. 13 is a cross-sectional elevation of a first preferred embodiment of fine-needle aspiration apparatus of the present invention:

FIG. 14 is a cross-sectional view of the fine-needle aspiration apparatus of FIG. 13 taken along line XIV--XIV;

FIG. 15 is a cross-sectional view of the fine-needle apparatus of FIG. 13 taken along line XV--XV;

FIG. 16 is a top cross-sectional view of the fine-needle apparatus of FIG. 13;

FIG. 17 is a schematic diagram illustrating the control sequence of the first embodiment of the present invention;

FIG. 18 is a control circuit for the first embodiment of the present invention;

FIGS. 19a and 19b are cross-sectional views illustrating modifications of the first embodiment of the present invention;

FIGS. 20a and 20b are cross-sectional views illustrating still further modifications of the first embodiment of the present invention;

FIG. 21 is a cross-sectional view of a reservoir test apparatus for use with the first embodiment of the present invention;

FIG. 22 is a cross-sectional view of a manual second embodiment of the present invention;

FIG. 23 is a cross-sectional view of a modification of the manual second embodiment of the present invention;

FIGS. 24a-24c are cross-sectional views of a manual third embodiment of the present invention; and

FIG. 25 is a cross-sectional view of an automatic fourth embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1a-1f schematically illustrate the positions of a needle 2, stylet 3, syringe 4 and plunger 5 relative to a fixed casing 1 and sheath 6 during a fine needle aspiration procedure using the first preferred embodiment of the apparatus of the present invention. More specifically, the schematic representation illustrates the movements of a first movable unit comprised of needle 2, syringe 4 and the means for longitudinally moving the same, and a second movable unit comprised of stylet 3, plunger 5 and means for longitudinally moving the same. The first and second movable units are adapted for movement relative to one another or together as a carriage assembly. Many of the movements of the needle, stylet, syringe and plunger illustrated in FIGS. 1a-1f are common to several embodiments of the invention, as discussed in more detail herein with reference to specific embodiments of the invention.

In FIG. 1a, the carriage (including the first and second movable units) is in its initial position "A". To commence aspiration of suspect tissue, the operator manually aligns the tips of the sheath, needle and stylet at or near the region to be sampled, hereinafter referred to as the target area. The operator then initiates the automatic aspiration procedure by, for example, manually triggering a switch located adjacent a pistol grip of the apparatus.

In accordance with a first preferred embodiment of the present invention, upon initiation of the automatic aspiration procedure, the carriage (and hence the needle 2 and stylet 3) moves forward a first predetermined distance to the position "B" shown in FIG. 1b. This movement advances the tips of the needle and stylet past the end of the sheath into the target area. This step is particularly desirable for those instances where it is not practical to manually position the tips of the needle and stylet at the target position (e.g., when the target area is in a remote region, such as the prostate gland). Automation of this step facilitates standardization of the aspiration procedure and helps ensure that the operator does not overshoot or undershoot the target area. When the present invention is used in an environment where the tips of the needle and stylet can be accurately, conveniently and safely manually positioned into the target area, this step can be omitted.

FIG. 1c illustrates the next step in the operation of the first embodiment, wherein after the initial forward movement of the carriage (position "B"), the carriage moves backwards a second predetermined distance to a position "C" located between positions "A" and "B". This step, which is omitted in manual embodiments of the invention, is in accord with a fail-safe aspect of the present invention, discussed in more detail below, whereby when power is cut off from the device, all carriage components are brought to a fully retracted position.

FIG. 1d illustrates the next step of the aspiration procedure in which the second movable unit, which includes the plunger 5 and the stylet 3, is retracted relative to the first movable unit, which includes the syringe 4 and the needle 2, to an extended carriage position. In accordance with the present invention, and as discussed in more detail herein, this step serves at least two important functions. First, retraction of the stylet provides a passage between the tip of the needle and a larger diameter cell sample storage portion of the needle located rearwardly of the tip of the needle. Second, retraction of the plunger simultaneously reduces the pressure in the cell sample storage portion of the needle. Because the retraction of the second movable unit relative to the first movable unit both opens a passage between the tip of the needle and the cell sample storage portion of the needle and creates a partial vacuum in the cell sample storage portion of the needle, a suction force is created at the tip of the needle causing sample material to be drawn into the cell sample storage portion of the needle.

Although cell sample is immediately drawn into the cell sample storage portion as the plunger is withdrawn, reciprocation of the needle within the target area is required to increase the sample yield. Thus, in accordance with the present invention, the carriage (while in the extended position) is reciprocated between the positions illustrated in FIGS. 1d and 1e, i.e., between positions "B" and "C".

After sufficient sample has been collected, the reciprocation cycle terminates. The second movable unit (including the stylet 3 and plunger 5) is then returned to a forward position as indicated in FIG. 1f so as to occlude the passage between the needle tip and the cell sample storage portion of the needle. Additionally, the return of the stylet and plunger to the forward position seals and removes the vacuum from the cell sample storage portion of the needle.

After the second movable unit is fully returned to the position shown in FIG. 1f, the carriage is returned to the position shown in FIG. 1a thus completing the aspiration procedure. The operator then withdraws the apparatus from the patient, removes the sheath, opens a cover of the apparatus, removes the syringe and needle from the apparatus, disconnects the syringe and stylet from the needle, connects a second syringe (filled with air) to the needle, and expresses the collected cell sample from the needle onto a slide. At this time, the cytological analysis of the cell sample can be performed. Additionally, since the apparatus is restored to its original state as shown in FIG. 1a and all components that were in contact with the patient (i.e., needle 2, stylet 3, sheath 6) are discarded, the apparatus is ready to receive a new sterile sheath, needle and syringe assembly for the next fine needle aspiration procedure. Sterilization of the reusable portion of the apparatus is not required.

An important feature of the present invention is the unique construction of the needle and stylet which allows the aspiration procedure to be completed automatically. Moreover, the configuration of the needle and stylet obviates the need for removal of the stylet before commencing the procedure and allows the sample storage portion of the needle to be fully sealed during both the penetration and withdrawal stages of the procedure. Finally, the configuration of the needle and stylet facilitates removal of a cytological sample without coring the target area.

A preferred needle construction is described hereinafter with reference to FIGS. 2-8. FIG. 2 is a partial cross-sectional view of a needle 2, a stylet 3 and a needle sheath 6. As shown in FIGS. 2-8, the stylet 3 has a uniform circular cross-section along its length. The needle tube, however, has a variable cross-section. In particular, the needle includes a narrow diameter portion 16 (e.g., 22 gauge) and an expanded diameter portion 17 (e.g., 18 gauge). Both portions of the needle 2 are hollow thus permitting the stylet 3 to extend therethrough.

The exterior diameter of the stylet is substantially the same as the interior diameter of the narrow portion 16 of the needle so that when the stylet extends fully through the narrow diameter portion 16 of the needle, the stylet occludes the tip 19 of the needle and substantially occupies the entire interior space of the narrow portion of the needle to thereby seal the needle. Further, when in the fully extended position, the tip of the stylet 26 and the tip of the needle 19 are substantially continuous so as to provide a substantially continuously tapering leading edge for effectively penetrating and separating tissue without coring when the needle and stylet protrude beyond the sheath as illustrated in FIG. 8.

The interior surface of the expanded portion 17 of the needle has a larger diameter than stylet 3. Thus, even with the stylet extended into the expanded portion of the needle, a space is provided between the exterior diameter of the stylet and the interior diameter of the expanded portion of the needle. This space defines a chamber or volume, which is referred to herein as the cell sample storage portion 20