Needle kit and method for microwave ablation, track coagulation, and biopsy

#The present invention relates generally to a modular biopsy, ablation and delivery needle apparatus that allows a biopsy needle to be inserted into a delivery needle, and, absent the biopsy needle, allows an inner ablation needle to be introduced and engaged with the delivery needle to form a microwave antenna. The present invention also relates to methods for biopsying and ablating tumors and coagulating the insertion track using the modular apparatus.

#In the U.S., the lifetime chance of developing an invasive cancer is 46% for men and 38% for women. Cancer is the second leading cause of death in the U.S. and is a major cause of death worldwide. In the U.S. in 1998, there were an estimated 564,800 deaths due to cancer with 1,228,600 new cases of invasive cancer diagnosed. Over 40% of the deaths are associated with primary and metastatic liver cancer.

#Outside the U.S., primary liver cancer (hepatocellular carcinoma) accounts for one of the largest cancer-related mortalities in the world (about 1,250,000 per year) in adults. In Japan, liver cancer is the third most common cause of death in men.

#FIG. 1a is a side view of a hollow delivery needle wherein the first connector comprises an outer portion of a coaxial connector according to one embodiment of the invention.

#FIG. 1b is an isometric view of the proximal end of the hollow delivery needle of FIG. 1a.

#FIG. 1c is a side view of an ablation needle wherein the second connector comprises an inner portion of a coaxial connector according to one embodiment of the invention.

#Turning now to FIGS. 1a through 2 and 13 through 15, various embodiments of the modular needle apparatus are illustrated. In each of these embodiments, the modular needle apparatus includes a hollow delivery needle 10 having a proximal port 15 opening into a lumen 20 which extends through the delivery needle 10 to its distal end. The lumen 20 is sized to accommodate alternately a biopsy needle 30 and an ablation needle 35. Both the biopsy needle 30 and the ablation needle 35 are longer than the delivery needle 10 such that when either is inserted into the proximal port 15, a distal projection may extend from the distal end of the delivery needle 10. In this fashion, the biopsy needle 30 may obtain a tissue sample. In addition, the distal projection of the ablation needle 35 forms a microwave antenna 40 for performing tissue ablation. In certain embodiments, illustrated in FIGS. 1a through 1g, inserting the ablation needle 35 into the lumen 20 of the delivery needle 10 forms a coaxial transmission line 50 which supplies power to the microwave antenna 40. In such embodiment s, the delivery needle 10 comprises a conductive material that functions as the outer conductor 16 of the coaxial transmission line 50, while a center conductor 55 of the ablation needle 35 circumferentially surrounded by dielectric material 60 acts as the center conductor and dielectric of the coaxial transmission line 50. Delivery needle 10 preferably further comprises a jacket 17 of electrically and/or thermally insulating material such as parylene or Teflon® which at least partially surrounds outer conductor 16 (shown in FIG. 1a). Delivery needle 10 may have a flat or a sharpened distal end. As used herein, a “flat” distal end indicates a bevel of 90° as described in Andriole et al., Biopsy Needle Characteristics Assessed in the Laboratory, Radiology 148: 659-662, September 1983, the contents of which are hereby incorporated by reference.

#In an alternate embodiment, illustrated in FIGS. 13 through 15, the microwave antenna 40 couples to a transmission line 61 contained entirely within the ablation needle 35 such that the delivery needle 10 has no electrical transmission function, although it may provide additional shielding and/or act as an insulator. Thus, in these embodiments, the delivery needle 10 and the ablation needle 35 do not couple together to create the coaxial transmission line 50 of FIG. 1d.

#It is to be noted that by coupling the delivery needle 10 with the ablation needle 35 to create the coaxial transmission line 50 feeding the microwave antenna 40, the largest diameter that must enter the tissue may be kept very small, preferably of 17 gauge or higher, and more preferably 18 gauge or higher. As used herein, “gauge” shall refer to the outer diameter of a needle unless otherwise indicated. For such embodiments, the ablation needle 35 comprises a center conductor 55 circumferentially surrounded by a dielectric material 60. The dielectric material 60 may comprise a ceramic material, a fluoropolymer such as polytetrafluoroethylene (PTFE) or expanded PTFE, polyethylene (PE), silicone or other suitable materials. The dielectric material 60 is sized to fill the lumen 20 of the delivery needle 35. The diameter of the center conductor 55 and the inner diameter of the outer conductor 16 are chosen according to the equation: