System and method for monitoring ablation size

1. A system for monitoring ablation size, comprising:

a power source; and

a microwave antenna configured to transmit microwave energy from the power source to tissue to form an ablation zone, the microwave antenna including:

an elongate shaft;

a plurality of proximal spaced-apart electrodes disposed on the elongate shaft, each of the plurality of proximal spaced-apart electrodes having a threshold impedance associated therewith corresponding to a radius of the ablation zone;

a distal electrode disposed on the elongate shaft distally of the plurality of proximal spaced-apart electrodes;

a feedline having a distal radiating section disposed within the elongate shaft, the distal radiating section detached and electrically distinct from the distal electrode;

a first sensor disposed on at least one of the plurality of proximal spaced-apart electrodes; and

a second sensor disposed on the distal electrode,

wherein a closed loop path is present between each electrode of the plurality of proximal spaced-apart electrodes and the distal electrode such that impedance is measurable between each electrode of the plurality of proximal spaced-apart electrodes and the distal electrode, and wherein the microwave antenna includes a wire serially connecting each of the plurality of proximal spaced-apart electrodes.

2. The system according to claim 1 , wherein the plurality of proximal spaced-apart electrodes is disposed along a longitudinal axis of the elongate shaft and in electrical communication with one another.

3. The system according to claim 1 , wherein the elongate shaft includes a distal tip and the distal electrode is disposed at the distal tip.

4. The system according to claim 1 , wherein the microwave antenna includes a dielectric sheath positioned along the elongate shaft and encasing the plurality of proximal spaced-apart electrodes and the distal electrode to allow current to flow from the plurality of proximal spaced-apart electrodes to the distal electrode.

5. The system according to claim 1 , wherein the plurality of proximal spaced-apart electrodes is disposed in a linear configuration on a distal portion of the elongate shaft.

6. The system according to claim 1 , further comprising an ablation zone control module in operative communication with the microwave antenna and the power source and configured to instruct the power source to adjust a parameter of the microwave energy based on a signal corresponding to the impedance measured between the first and second sensors.

7. The system according to claim 1 , further comprising a fluid pump configured to supply a cooling fluid to the microwave antenna for cooling the microwave antenna.

8. A microwave antenna for delivering microwave energy to tissue to form an ablation zone, the microwave antenna comprising:

an elongate shaft;

a plurality of proximal spaced-apart electrodes disposed on the elongate shaft, each of the plurality of proximal spaced-apart electrodes having a threshold impedance associated therewith corresponding to a radius of the ablation zone;

a distal electrode disposed on the elongate shaft distally of the plurality of proximal spaced-apart electrodes;

a feedline having a distal radiating section disposed within the elongate shaft, the distal radiating section detached and electrically distinct from the distal electrode;

a first sensor disposed on at least one of the plurality of proximal spaced-apart electrodes; and

a second sensor disposed on the distal electrode, the first and second sensors being longitudinally spaced from one another along a longitudinal axis of the elongate shaft,

wherein a closed loop path is present between each electrode of the plurality of proximal spaced-apart electrodes and the distal electrode such that impedance is measurable between each electrode of the plurality of proximal spaced-apart electrodes and the distal electrode, and further comprising a wire serially connecting each of the plurality of proximal spaced-apart electrodes.

9. The microwave antenna according to claim 8 , wherein the plurality of proximal spaced-apart electrodes is disposed along the longitudinal axis of the elongate shaft and in electrical communication with one another.

10. The microwave antenna according to claim 8 , wherein the elongate shaft includes a distal tip and the distal electrode is disposed at the distal tip.

11. The microwave antenna according to claim 8 , further comprising a dielectric sheath positioned along the elongate shaft and encasing the plurality of proximal spaced-apart electrodes and the distal electrode to allow current to flow from the plurality of proximal spaced-apart electrodes to the distal electrode.

12. The microwave antenna according to claim 8 , wherein the plurality of proximal spaced-apart electrodes is disposed in a linear configuration on a distal portion of the elongate shaft.

13. A microwave antenna for delivering microwave energy to tissue to form an ablation zone, the microwave antenna comprising:

an elongate shaft;

a plurality of proximal spaced-apart electrodes disposed on the elongate shaft;

a distal electrode disposed on the elongate shaft distally of the plurality of proximal spaced-apart electrodes; and

a feedline having a distal radiating section disposed within the elongate shaft, the distal radiating section detached and electrically distinct from the distal electrode;

wherein a closed loop path is present between each electrode of the plurality of proximal spaced-apart electrodes and the distal electrode such that impedance is measurable between each electrode of the plurality of proximal spaced-apart electrodes and the distal electrode, and wherein the microwave antenna includes a wire serially connecting each of the plurality of proximal spaced-apart electrodes.