Irreversible electroporation (IRE) based on field, contact force and time
A method includes, using a probe, applying irreversible electroporation (IRE) pulses to tissue over a time period to form a lesion in the tissue. A contact force applied to the tissue by the probe is measured over the time period. An IRE index is calculated based on the measured contact force and on a power level of the IRE pulses. Application of the IRE pulses to the tissue is ceased in response to the calculated IRE index reaching a prespecified target IRE index value.
1. A method of applying irreversible electroporation pulses (IRE) to tissue to form a lesion, the method comprising:
selecting a prespecified target IRE index value, wherein the prespecified target IRE index value is not a size of the lesion but a repeatable predictor of the size of the lesion, the size of the lesion comprising a volume, a depth and a diameter of the lesion;
using a probe, applying the IRE pulses to the tissue over a time period to form the lesion;
measuring instantaneous contact forces and instantaneous power levels of the IRE pulses applied to the tissue by the probe over the time period;
calculating, on a recurring basis, estimated IRE index values index using an integral over the time period of a product of the instantaneous measured contact forces, respectively, raised to a first calibrated non-unity exponent and the measured instantaneous power levels of the IRE pulses, respectively, raised to a second calibrated non-unity exponent, the calculated estimated IRE index values corresponding respectively to an estimated volume, an estimated depth and an estimated diameter of the lesion; and
ceasing application of the IRE pulses to the tissue in response to a value of the calculated estimated IRE index values reaching the prespecified target IRE index value.
2. The method according to claim 1 , and comprising presenting the calculated estimated IRE index values and the prespecified target IRE index value to a user.
3. The method according to claim 1 , further comprising measuring the instantaneous power levels by measuring a peak voltage of the IRE pulses.
4. The method according to claim 1 , further comprising simulating an electric field produced by the IRE pulses.
5. A system for applying IRE pulses to tissue to form a lesion, the system comprising:
a probe configured to apply the IRE pulses to the tissue over a time period to form the lesion in the tissue; and
a processor configured to:
receive a selection of a prespecified target IRE index value, wherein the prespecified target IRE index value is not a size of the lesion but a repeatable predictor of the size of the lesion, the size of the lesion comprising a volume, a depth and a diameter of the lesion;
measure instantaneous contact forces and instantaneous power levels of the IRE pulses applied to the tissue by the probe over the time period;
calculate, on a recurring basis, estimated IRE index values using an integral over the time period of a product of the instantaneous measured contact forces respectively, raised to a first calibrated non-unity exponent and the measured instantaneous power levels of the IRE pulses, respectively, raised to a second calibrated non-unity exponent, the calculated estimated IRE index values corresponding respectively to an estimated volume, an estimated depth and an estimated diameter of the lesion; and
cease application of the IRE pulses to the tissue in response to a value of the calculated estimated IRE index values reaching the prespecified target IRE index value.
6. The system according to claim 5 , wherein the processor is further configured to present the calculated estimated IRE index values and the prespecified target IRE index value to a user.
7. The system according to claim 5 , wherein the processor is further configured to measure the instantaneous power levels by measuring a peak voltage of the IRE pulses.
8. The system according to claim 5 , wherein the processor is further configured to simulate an electric field produced by the IRE pulses.