BIOPSY NEEDLE

Abstract: A biopsy needle device includes an outer cannula (12) having a pointed, tissue-penetrating distal end and a side notched stylet (14) located within the cannula (12). The stylet (14) and cannula (12) are axially movable with respect to each other. The stylet (14) is constructed from a solid rod having a notch (8) near the distal end. The notch (8) is bordered in portions along its length by a walled region to at least in part define a protected sample containment space. The stylet (14) includes a pointed, tissue-penetrating distal end. The notch (8) defines a full cylindrical region, and the walled region has a semicircular cross section.

Description: BIOPSY NEEDLE This invention relates to biopsy needles. Background of the Invention A biopsy needle instrument is frequently used to obtain a tissue specimen for microscopic examination to determined malignancy, while subjecting the patient to the least trauma. Typically, the instrument consists of a long, thin probe, termed a stylet, within a close- fitting hollow needle, termed a cannula. A firing device first projects the stylet into the tissue, followed immediately by the cannula. The stylet has a notch into which tissue will prolapse when the stylet enters the tissue. As the cannula subsequently slides over the stylet, it severs the prolapsed tissue from the surrounding mass and captures the prolapsed tissue as a specimen within the notch. The instrument then is typically withdrawn and the piece of tissue removed from the stylet. Summary of the Invention In an aspect, the invention features a biopsy needle device of the type including an outer cannula having a pointed, tissue penetrating distal end and a side-notched stylet located within the cannula. The stylet and the cannula are axially movable with respect to each other. The stylet is constructed from a solid rod member having a notch near the distal end. The notch is bordered in portions along its length by a walled region to at least in part define a protected sample- containment space. Embodiments may include one or more of the following features. The stylet includes a pointed, tissue penetrating distal end. The notch defines a full cylindrical region and the walled region has a semi- circular cross-section. The notch has a cross sectional area between about 90-97% of the diameter of the rod. The wall thickness of the walled region is in the range of 0.008"-0.013". The cross section of the rod is in the range of 14 to 18 gauge. The length of the notch is about 10-20 mm. The length of the notch is about 17 mm. In another aspect, the invention features a method of taking a biopsy sample, including providing a biopsy needle of the type including an outer cannula having a pointed, tissue penetrating distal end, and a side-notch stylet located within the cannula. The stylet and the cannula are axially movable with respect to each other. The stylet is constructed substantially of a solid rod member having a notch near the distal end. The notch is bordered along its length by a thin-walled region of the rod member to define a sample-containment space. The method includes aligning a distal end of the stylet with the pointed, tissue penetrating distal end of the cannula, introducing the biopsy needle into a tissue to be sampled, advancing the stylet distally so that tissue to be sampled prolapses into the notch, advancing the cannula distally to sever the tissue and contain the tissue in the sample-containment space and removing the biopsy needle. The method may include taking a sample from a hard cancerous lesion. The inventions have many advantages. For example, the biopsy needle stylet provides a large, substantially enclosed sample-containment space for receiving and protecting a large tissue sample that exhibits low crush artifact. Typically, the stylet notch is formed in a continuous solid rod and has a short axial length to maintain, generally, the strength of the stylet so that large samples can be taken from hard tissues, such as hard cancerous lesions or even bone (or if the needle should accidently strike bone) , without buckling or other failure. Still further advantages, features, and aspects follow. Brief Description of the Drawings Fig. 1 is a cross-sectional view of a type of needle notch commonly used in conventional biopsy needles; Fig. 2 is a top view of an embodiment of a biopsy needle device according to the invention; Fig. 2a is a cross-sectional view of the grooved notch of the biopsy needle of Fig. 2 taken along line 2a- 2a of Fig. 2; and Fig. 2b is a side view of the distal region of the biopsy needle of Fig. 2. Description of the Preferred Embodiments Referring to Fig. 1, commonly used biopsy needles have a stylet notch 8 that has an open shelf-like area. For example, the notch may have a semi-cylindrical shape that is formed by sectioning a rod. The sample prolapses onto the shelf and is held there by the inner surfaces of a cannula that passes over the needle to sever the tissue from the body. Referring to Fig. 2, a biopsy needle device 10 according to the invention includes a handle 11, a hollow cannula 12, and a stylet 14. Stylet 14 includes a sharp tip 20 at distal end 22. Proximal of the tip 20, the stylet includes a grooved notch 16, to be discussed in more detail immediately below, that enables large samples to be taken and protected while maintaining the strength of the needle so that it can penetrate hard lesions without buckling. Cannula 12 and stylet 14 are axially movable with respect to each other. In use, biopsy needle 10, with stylet 14 within cannula 12, is inserted into the body to a tissue site to be sampled. Stylet 14 is then advanced to expose grooved notch 16. Tissue prolapses into grooved notch 16 and cannula 12 is advanced shearing the tissue to sever a sample. The sample is held protected inside the grooved notch. Biopsy needle device 10 is then removed from the body. The cannula is retracted, the sample is removed from the notch, and the sample is analyzed for malignancy, e.g. by DNA or other testing. A mechanism for driving the biopsy needle is taught in commonly-owned U.S. Patent Nos. 4,958,625 and 5,195,533. Referring as well to Fig. 2a, needle stylet 14 is a solid rod except for grooved notch sample-containment area 16 located in distal region 18. The grooved notch defines a full cylindrically shaped volume having a cross-sectional area only slightly less than the cross sectional area of stylet 14. The lower portions of the region are bordered by a walled, semi-circular section 24 which can protect large portions of the sample from engaging the cannula as it slides over the stylet at high velocity. The length of the notch is kept relatively short to prevent buckling and allow for high torque transmission. Even with a short notch, a relatively large sample can collected because the lower portion of the notch, bordered by the semi-circular portion of the stylet provide a large area for receiving sample. The grooved notch can be formed by electric discharge machining or grinding a solid rod of 304 stainless steel. In an embodiment, the grooved notch is located about 0.210"-0.260" from the distal end 22 of stylet 14. The wall thickness of semicircular section 24 is about 0.008"-0.013" for an 14-18 gauge stylet, or approximately 3-7% of the diameter of stylet 14. The length of grooved notch 16 is about 10-20 mm, for example about 17 mm. By comparison to a stylet of the same gauge with a semi-cylindrical notch of the same length, the grooved notch typically has a cross-sectional area approximately 35 - 40% larger, can take a large sample that provides approximately 35 - 40% more DNA per sample, and can take a sample with a tissue weight that is 23.4% greater for a 14 gauge needle, 27% greater for a 15 gauge needle, and 30.8% greater for a 18 gauge needle. Tissue samples are tightly packed within the grooved notch and after removal from the biopsy needle have been found to be 10.2% longer for a 14 gauge needle and 5.7% longer for a 15 gauge needle, as compared to a semi-cylindrical notch biopsy needle. The increased notch volume permits a larger tissue sample to prolapse into the notch resulting in a larger specimen sampled from a wider, deeper area of the tissue. The ability to take a larger sample reduces the number of biopsies required and a single large biopsy sample providing a sufficient number of cells for histopathological evaluation taken in one biopsy is better than several smaller samples. The grooved notch biopsy design is particularly advantageous when taking samples where damage to small samples could prevent accurate analysis, e.g., in samples from hard cancerous lesions. The samples exhibit reduced crush artifact. The biopsy needle devices according to the invention can be used for sampling in many parts of the body. It can be used on all soft tissue, e.g., lung, kidney, liver and breast with that advantages of obtaining and protecting large samples. The grooved notch biopsy needle stylet design can be also used for penetrating very hard lesions or even bone because the columnar strength can be maintained without sacrificing sample size. In alternative embodiments, the cross sectional geometry of the walled section of grooved notch sample- containment area may vary. More than one grooved notch sample-containment area can be formed in axial sequence on t the stylet for multiple biopsy sampling. The grooved notch can used in other systems for taking multiple samples, such as described in of commonly owned U.S. Patent No. 5,195,533, The grooved notch can also be used to take deep tissue biopsy samples by placing the groove notch within a long flexible catheter body, as described in WO 94/26172. Still further embodiments are within the following claims.

Claims: CLAIMS 1. A biopsy needle device of the type including an outer cannula having a pointed, tissue penetrating distal end and a side-notched stylet located within said cannula, said stylet and said cannula being axially movable with respect to each other, wherein said stylet is constructed from a solid rod member having a notch near the distal end, said notch being bordered in portions along its length by a walled region to at least in part define a protected sample-containment space. 2. The biopsy needle device of claim 1 wherein said stylet comprises a pointed, tissue penetrating distal end. 3. The biopsy needle device of claim 1 wherein notch defines a full cylindrical region and said walled region has a semi-circular cross-section. 4. The biopsy needle of claim 3 wherein said notch has a cross sectional area between about 90-97% of the diameter of said rod. 5. The biopsy needle device of claim 3 wherein the wall thickness of said walled region is in the range of 0.008"-0.013". 6. The biopsy needle device of claim 5 wherein the cross section of said rod is in the range of 14 to 18 gauge. 7. The biopsy needle device of claim 6 wherein the length of said notch is about 10-20mm. 8. The biopsy needle device of claim 7 wherein the length of said notch is about 17 mm. 9. A method of taking a biopsy sample, comprising: providing a biopsy needle of the type including an outer cannula having a pointed, tissue penetrating distal end, and a side-notch stylet located within said cannula, said stylet and said cannula being axially movable with respect to each other, wherein said stylet is constructed substantially of a solid rod member having a notch near the distal end, said notch being bordered along its length by a thin-walled region of said rod member to define a sample-containment space, aligning a distal end of said stylet with said pointed, tissue penetrating distal end of said cannula, introducing said biopsy needle into a tissue to be sampled, advancing said stylet distally so that tissue to be sampled prolapses into said notch, advancing said cannula distally to sever said tissue and contain said tissue in said sample-containment space, removing said biopsy needle. 10. The method of claim 9 comprising taking a sample from a hard cancerous lesion.

Inventors: BATES JAMES, CHIN YEN, CHU MICHAEL S H, BATES, JAMES, CHIN, YEN, CHU, MICHAEL, S., H.
Applicants: BOSTON SCIENT CORP, BOSTON SCIENTIFIC CORPORATION
Application year: 1995
Main classification: A61B10
IPC codes: A61B10