An antenna assembly for microwave ablation can include a radiator for emitting a microwave for ablation; a coaxial cable for transmitting the microwave for ablation generated by a microwave generator to the radiator; an annular composite structure is provided around the coaxial cable for inhibiting an electromagnetic wave from propagating backwards along the coaxial cable. In some embodiment, the annular composite structure comprises an annular nonmetallic layer and an annular metallic layer located outside the annular nonmetallic layer. In some embodiments, the annular metallic layer is electrically insulated from the coaxial cable. In some embodiments, the antenna assembly can be used with a microwave ablation needle. The annular composite structure can inhibit the backward propagation of the microwave along the coaxial cable exterior wall. In some embodiments, circulation water enters the radiation zone, to avoid high temperatures of the head the ablation needle.

A microwave ablation system includes a microwave ablation antenna assembly, a generator, a first fluid supply source, and a second fluid supply source. The microwave ablation antenna assembly includes a fluid port for receiving fluid. The generator is coupled to the microwave ablation antenna assembly. The first fluid supply source is configured to be selectively in fluid communication with the fluid port to supply a first fluid to the microwave ablation antenna assembly. The second fluid supply source is configured to be selectively in fluid communication with the fluid port to supply a second fluid to the microwave ablation antenna assembly.

An electrosurgical device (10) is provided that is operable to deliver microwave energy within a controlled angular expanse to cause targeted tissue ablation. The device (10) comprises a blocking or reflecting material such as cylindrical members (34) that are laterally spaced from the antenna (20) that is operable to emit the microwave energy. The reflecting material creates regions in and/or surrounding the device into which sensors (51), such as thermocouple wires, may be placed to monitor a condition associated with the device or the patient's body.

An ablation device includes a feedline including an inner conductor having a distal end, an outer conductor coaxially disposed around the inner conductor, and a dielectric material disposed therebetween, an elongated electrically-conductive member longitudinally disposed at the distal end of the inner conductor and having a proximal end, a first balun structure disposed over a first portion of the outer conductor and positioned so that a distal end of the first balun structure is located at a first distance from the proximal end of the electrically-conductive member and a second balun structure disposed over a second portion of the outer conductor and positioned so that a distal end of the second balun structure is located at a second distance from the proximal end of the electrically-conductive member.

A novel monitoring method evaluates tissue ablation progress. An antenna in a distal portion of an ablation applicator sends and receives electrical information from the target tissue during ablation. The information is used to determine ablation progress. A related ablation monitoring system includes a power monitor and processor operable to evaluate ablation progress based on reflected electrical properties during the ablation. The invention has particular benefits when used in endoscopic-based microwave ablation.

An electrosurgical instrument for delivering microwave energy to biological tissue, in which a pair of conductive tuning elements are mounted in a radiating instrument tip to shape a microwave radiation profile of the instrument so that the radiation profile is constrained around the instrument tip. Such tuning elements may result in a radiation profile that is substantially spherical around the instrument tip, providing a well-defined ablation volume. The tuning elements act to improve the efficiency with which microwave energy can be delivered into target tissue.

A circular microwave ablation antenna is provided with a chamber for accommodating the coaxial cable and the conduit, the chamber and the conduit extend forward to the front end of the antenna. An emission window of the antenna is at least partially located in the conduit to enable the cooling medium to cool the emission window area of the antenna. The conduit of the microwave emission area is made of an insulation material, so that the microwave can radiate outward, and the rest of the conduit is made of a microwave shielding material. The choke ring located at the rear side of emission area is hermetically fixed to the conduit, so that the choke ring acts to block the microwave. A gap exists between the choke ring and the needle bar, and the gap is used for the backflow of the cooling medium.

A microwave system comprises: a microwave generator; and a microwave cable apparatus comprising a coaxial cable, wherein an exposed distal portion of an inner conductor of the coaxial cable is longer than an outer conductor of the coaxial cable, and wherein at least part of the exposed distal portion of the inner conductor is bent with respect to a longitudinal axis of the coaxial cable, thereby to provide a directional radiating element; wherein the microwave generator is configured to provide microwave energy to the cable apparatus at a frequency that provides directional radiation of microwave energy having a desired directionality from the radiating element.

A microwave ablation antenna assembly (20) incorporates a choke assembly (40) having a dielectric element (42) and a conducting element (48). The conducting element (48) is chosen from a group of elements of fixed length, but with differing electrical lengths for providing cancellation properties for different wavelengths of microwave energy.

An exemplary ablation system is provided. The system is designed for safe and efficacious energy delivery into tissue by, for example, emitting energy in a controlled, repeatable manner that allows for feedback and energy emission titration based on sensed parameters (e.g., tissue temperature) measured during ablation. The system may include a switching antenna for both heating of target tissue and radiometry to monitor the temperature of the heated tissue. For example, the switching antenna may include a monopole formed by proximal and distal radiating elements, such that the proximal radiating element includes a short to defeat a choke action of the proximal radiating element. The system further includes a processor for calculating the temperature of the target tissue and estimating volume of the ablation lesion based on the target tissue temperature.