WO2008142686A2

WO2008142686A2 - Ablation probe

Info

Publication number: WO2008142686A2
Application number: PCT/IL2008/000688
Authority: WO
Inventors: Roni Zvuloni; Yeshayahu Schatzberger
Original assignee: Uc-Care Ltd.
Priority date: 2007-05-21
Filing date: 2008-05-21
Publication date: 2008-11-27
Also published as: WO2008142686A3

Abstract

A device for tissue ablation at least by high frequency energy comprising at least one group of probes. Each group includes a couple of high frequency probes having a single pole and being adapted for individual disposition of the pole adjacent the tissue at a desired distance from the pole of the other probe, the poles constituting a dipole adapted to apply the energy to a first volume of the tissue. The device further comprises at least one cryo probe having a cryo tip and is adapted for the disposition of the cryo tip between the poles, for cooling the tissue, inducing ablation of a second volume of the tissue which is greater than the first volume.

Description

ABLATION PROBE

FIELD OF THE INVENTION

The present invention relates to devices and methods of tissue ablation either by heating the tissue by high-frequency energy or cooling it by cryo energy or by combination of the two.

BACKGROUND OF THE INVENTION

Radiofrequency (RF) ablation and cryoablation are two techniques applied in a minimally invasive manner to destroy biological tissue for medical treatment and usually used for local destroying of cancer tumors. The RF ablation is based on the destruction of tissue by heat, whereas the basis of the cryoablation is the destruction of tissue by freezing.

RF ablation technique requires the placement of a needle electrode (also known as probe) within the tissue. The high-frequency alternating current (for example 460- 480 KHz) induces temperature changes in the tissue. Since heat dissipates rapidly with increasing the distance from the electrode, the highest temperature is always in the closest proximity to electrodes. The heating process stops when electrical impedance of the tissue (resistance to RF current flow) increases to the extent that it resists the flow of any current. This increase in impedance has been attributed to tissue coagulation. As tissue temperature increases to between about 60°C and about 100°C, there is an instantaneous induction of irreversible cellular damage referred to as coagulation necrosis. The size and shape of the coagulation area depend on the tissue characteristics, the RF probe type, length of exposed tip, intensity of the application and the duration of treatment. There are other alternatives to RF ablation technique, such as microwave ablation, wherein the tissue is ablated by alternating high-frequency waves (about 2450 MHz), e.g. Urologix Inc. Targis and Prostatron^® Systems; Laser ablation e.g. Johnson and Johnson, Ethicon Endo-Surgery Inc. Interstitial Laser Coagulation , Indigo Optima System, HIFU ablation, eg. EDAP Ablatherm system and Focus Surgery Inc. sonablate 500 system, etc. There are known mono-polar and bi-polar RF ablation probes. A monopolar probe has a single pole and a ground electrode so that the electrical current is directed from probe towards the grounded electrode. A bi-polar probe has two spaced apart poles and the electrical current flows therebetween. Commercial RF ablation systems and probes are available from RITA Medical Systems, Inc., 46421 Landing Parkway, Fremont, CA 94538 USA Model 1500X , 460KHz 250W; Olympus /Celon AG medical instruments, Rheinstrasse 8 14513 Teltow, Germany model CelonPOWER & UC-CARE Ltd., Yokneam , Israel model UC-X50 ,480KHz, 50W etc.

Cryoablation technique usually involves inserting a cryo probe into tissue and then supplying a cryogen to the tip of the cryo probe. The tissue temperature is decreased to a temperature (from about -40⁰C to about -80°C) that correlates with the complete coagulation necrosis. Common cryoablation techniques involve the use of high pressure (e.g., about 80 psi) liquid Nitrogen systems or high pressure (e.g., 3000- 4500 psi) Argon gas systems (Endocare Inc, Irvine CA, Galil Medical Ltd. Yokneam, Israel), in which there is a utilization of the Joule-Thomson cooling effect, and the temperature of the fluid is further reduced when heat between the outflow and the inflow fluids is exchanged by comprising a heat exchanger, (the so-called "Joule- Thomson heat exchanger"). Usually, the freezing of the tissue is subsequently followed by its thawing (usually using a Helium gas or resistive heating), which leads to the disruption of cell membranes and induces cell destruction. The cell destruction is further accelerated upon the repetition of the freeze-thaw cycles, typical duration of which is about 10-12 minutes for freezing and about 10 minutes for thawing.

The coagulation area of the treated tissue may be increased by a combination of RF ablation and cryo-cooling techniques. Cooling the tissue greatly increases its impedance. Therefore, if the tissue surrounding RF probe has high impedance as a result of the pre-cooling, the RF current will be forced to flow around that tissue, in order to find tissue of lower impedance, thereby allowing wider areas of coagulation.

US 6,379,348 discloses a combined electrosurgical-cryosurgical instrument for tissue ablation. The instrument comprises a shaft having a proximal end and a distal end, the distal end being electrically and thermally conductive; a radiofrequency insulation sheath surrounding the outer surface of the shaft; a cryo-insulation sheath surrounding a surface of the shaft; a radiofrequency power supply source; a cryogen supply tube within the shaft; and a cryogen supply source connected to the cryogen supply tube. The power source provides electrical energy to the distal end of the shaft, and the cryogen supply tube provides a cryogen to the distal end of the shaft.

Hines-Peralta et al. (Journal of Vascular and Interventional Radiology 15: 1111- 1120, 2004) describe an early experience to simultaneously perform cryoablation and bipolar RF ablation.

US 7,097,641 discloses a catheter with cryogenic and heating ablation. A catheter includes a cryoablation tip with an electrically-driven ablation assembly for heating tissue. The cryoablation tip may be implemented with a cooling chamber through which a controllably injected coolant circulates to lower the tip temperature, and having an RF electrode at its distal end. The RF electrode may be operated to warm cryogenically-cooled tissue, or the coolant may be controlled to conductively cool the tissue in coordination with an RF treatment regime, allowing greater versatility of operation and enhancing the lesion size, speed or placement of multi-lesion treatment or single lesion re-treatment cycles. In one embodiment a microwave energy source operates at a frequency to extend beyond the thermal conduction depth, or to penetrate the cryogenic ice ball and be absorbed in tissue beyond an ice boundary, thus extending the depth and/or width of a single treatment locus, hi another embodiment, the cooling and the application of RF energy are both controlled to position the ablation region away from the surface contacted by the electrode, for example to leave surface tissue unharmed while ablating at depth or to provide an ablation band of greater uniformity with increasing depth. The driver or RF energy source may supply microwave energy at a frequency effective to penetrate the ice ball which develops on a cryocatheter, and different frequencies may be selected for preferential absorption in a layer of defined thickness at depth in the nearby tissue. The catheter may operate between +70⁰C and -70°C for different tissue applications, such as angioplasty, cardiac ablation and tissue remodeling, and may preset the temperature of the tip or adjacent tissue, and otherwise overlay or delay the two different profiles to tailor the shape or position where ablation occurs or to speed up a treatment cycle. SUMMARY OF THE INVENTION

According to one aspect of the present invention there is provided a device for tissue ablation at least by high frequency energy comprising at least one group of probes, the or each group including: a couple of high frequency probes having a single pole and being adapted for individual disposition of said pole adjacent said tissue at a desired distance from the pole of the other probe, the poles constituting a dipole adapted to apply said energy to a first volume of said tissue; and at least one cryo probe having a cryo tip and adapted for the disposition of the cryo tip between said poles, for cooling said tissue, to ablate a second volume of said tissue which is greater than said first volume.

The device may further comprise a plurality of the groups of probes wherein at least one of said high frequency probes constitutes a part of said couple of high frequency probes in more than one of said groups. This may allow flexibility of covering different areas of tissue to be treated with a limited number of probes. The device may further comprise a guiding matrix having a plurality of apertures each adapted for guiding one probe therethrough, the apertures being arranged in a pattern allowing different dispositions of the high frequency and cryo probes to form a plurality of the groups of probes in accordance with a desired accurate volume to which said energy is to be applied. According to another aspect of the present invention there is provided a method for tissue ablation at least by high frequency energy, the method comprising: providing at least one couple of high frequency probes each having a single pole, and at least one cryo probe having a cryo tip; individually introducing each of said high frequency probes to dispose their poles at a desired distance from each other, to form a dipole suitable for applying said energy to a first volume of said tissue;

- introducing the cryo tip between said poles for cooling said tissue, to ablate a second volume of said tissue which is greater than said first volume.

The increase of the ablated volume in both the device and the method defined above may be achieved by the cryo probe being adapted for cooling the tissue to be ablated to a temperature higher than that required for cryoablation of the tissue, thereby increasing the electrical resistance of said tissue without ablating thereof.

According to another aspect of the present invention there is provided monopolar probe for thermal ablation of a tissue by applying to the tissue of high frequency energy, having a single pole adapted for being connected to a high frequency energy source for allowing electrical current to pass through said tissue, and a cryo component adapted for being connected to a cryo energy source for cooling the tissue to be ablated to a temperature higher than that required for cryoablation of the tissue, thereby increasing the volume ablated by said high frequency energy. According to still further aspects of the present invention there is provided a method for thermal ablation of a tissue by applying to the tissue of high frequency energy, the method comprising: providing a monopolar probe having a single pole adapted for being connected to a high frequency energy source for allowing electrical current to pass through said tissue;

- providing a cryo component adapted for being connected to a cryo energy source for cooling the tissue to be ablated to a temperature higher than that required for cryoablation of the tissue, thereby increasing the volume ablated by said high frequency energy. The cryo energy source used with the monopolar probe referred to above is adapted to provide such cryo energy thereto as to cool the tissue to a temperature is lower than that required for cryoablation of the tissue.

According to still another aspect of the present invention there is provided a probe for cryoablation of a tissue by applying to the tissue of cryo energy, having a cryo component adapted for being connected to a cryo energy source for cooling the tissue to a temperature required for cryoablation thereof, and high frequency energy electrode assembly adapted for being connected to a high frequency energy source to allow passing through said tissue of high frequency current lower than that required for thermal ablation of tissue, for thawing the cooled tissue. According to another aspect of the present invention there is provided a method for cryoablation of a tissue by applying to the tissue of cryo energy, comprising applying to the tissue of at least one cryablation cycle, the cycle comprising: - applying cryo energy to the tissue for a first time interval, and thereby cooling the tissue to a temperature required for cryoablation thereof; and

- subsequently applying to the cryoablated tissue for a second time interval of high frequency energy lower than that required for thermal ablation of tissue, thereby thawing the cooled tissue. The use of high frequency energy for thawing tissue treated for cryoablation may essentially reduce the entire treatment duration because of the more efficient way of the dissipation of the energy in and around the pre-cooled regime. Any of the probes previously described may comprise one or more of the following features:

• High frequency probes may further comprise thin isolation, allowing heat transfer therethourgh.

• Cryo probes may further comprise a Joule-Thomson configuration. • Cryo probes may further comprise a Joule-Thomson heat exchanger configuration.

According to a still other aspect of the invention there is provided a system for tissue ablation comprising one or more probes, a cryo source adapted to provide to at least one of said probes first cryo energy required for cryo ablation of said tissue and adapted to provide to at least one of said probes second cryo energy for cooling the tissue to be ablated to a temperature higher than that required for cryoablation; a high energy source adapted to provide to at least one of said probes first high frequency energy required for thermal ablation of said tissue and adapted to provide to at least one of said probes second high frequency energy lower than that required for thermal ablation of the tissue; and a control module to control the activation of said one or more probes by controlling the application thereto of one or more of the following: the first cryo energy, the second cryo energy, the first high frequency energy and the second high frequency energy.

The system may include the following probes or their combinations: • A monopolar or bipolar high-frequency probe adapted for being connected to a high frequency source providing thereto a high frequency energy required for thermal ablation of said tissue, or a high frequency energy lower than that required for thermal ablation of the tissue. The probe is further adapted for being connected to a cryo source providing thereto a cryo energy required for cryo ablation of said tissue or cryo energy for cooling the tissue to be ablated to a temperature higher than that required for cryoablation. • A monopolar or bipolar high-frequency probe adapted for being connected to a high frequency source providing thereto a high frequency energy required for thermal ablation of said tissue, or a high frequency energy lower than that required for thermal ablation of the tissue.

• A cryo probe adapted for being connected to a cryo source providing thereto a cryo energy required for cryo ablation of said tissue or cryo energy for cooling the tissue to be ablated to a temperature higher than that required for cryoablation.

• A probe adapted for being connected to a high frequency source providing thereto a high frequency energy required for thermal ablation of said tissue, and to a cryo energy source for cooling the tissue to be ablated to a temperature higher than that required for cryoablation, thereby increasing the volume to be ablated.

• A probe adapted for being connected to a cryo energy source providing thereto a cryo energy required for cryo ablation of said tissue, and to a high frequency energy source for thawing the treated tissue by a high frequency energy lower than that required for thermal ablation thereof. The system as described above may be used for different kinds and conditions of treatment, for different treatment areas and/or for different combinations of both.

The system as described above provides several remarkable advantages such as the ablation of a significantly larger area with each probe compared to commercially available systems. It also provides a remarkable advantage with the ability to accurately ablate tumors of different shape without damaging the surrounding tissue compared to commercially available systems. It also allows flexibility of covering different areas of tissue to be treated with a limited number of probes. It also allows shortening the overall procedure time during repeatable freeze-thaw ablation cycles compared to commercially available systems. The system can be used together with imaging devices such as

Ultrasound and MRI. Cryo cooled regimes are real time visualized via imaging devices.

Thus using a set of combined probes, initial cooling of the treated tissue provides accurate imaging information on the location of the probe tips within the tissue. With this information high frequency energy can be further used from these probe tips to the right extent and time in order to better cover tumors in a tissue without damaging surrounding tissue.. The control module may further comprise a man machine interface (MMI) for controlling desired parameters before, after and during the procedure.

The system may further comprise an imaging system such as ultrasound system and the control of the system is further achieved via data that is transferred either manually by the users or automatically from the imaging system to the control system. According to a still other aspect of the invention there is provided a bipolar probe for thermal ablation of a tissue comprising a housing with a cryo component, at least a part of said housing being adapted to be operated as a first pole, a first, isolation layer disposed over said housing leaving said part of the housing exposed to the tissue to be ablated, a second, conductive layer disposed over the first isolation layer, at least a portion of which is adapted to be operated as a second pole, and a third, isolation layer disposed over said second layer leaving said part of the second layer exposed to the tissue to be ablated, said first pole being adapted for connection to a high frequency energy source for allowing electrical current to pass from said first pole to said second pole through said tissue, and said cryo component adapted for being connected to a cryo energy source for cooling said tissue to a temperature higher than that required for cryoablation of the tissue, thereby increasing the volume ablated by said high frequency energy.

According to a still other aspect of the invention there is provided a bipolar probe for thermal ablation of a tissue comprising a housing with a cryo component, at least a part of said housing being adapted to be operated as a first pole, a first, isolation layer disposed over said housing leaving said part of the housing exposed to the tissue to be ablated, a second, conductive layer disposed over the first isolation layer, at least a portion of which is adapted to be operated as a second pole, and a third, isolation layer disposed over said second layer leaving said part of the second layer exposed to the tissue to be ablated, said first pole being adapted for connection to a high frequency energy source for allowing electrical current to pass from said first pole to said second pole through said tissue, and said cryo component adapted for being connected to a cryo energy source for cooling said tissue to a temperature higher than that required for cryoablation of the tissue, thereby increasing the volume ablated by said high frequency energy.

A bipolar probe for cryoablation ablation of a tissue comprising a housing with a cryo component, at least a part of said housing being adapted to be operated as a first pole, a first, isolation layer disposed over said housing leaving said part of the housing exposed to the tissue to be ablated, a second, conductive layer disposed over the first isolation layer, at least a portion of which is adapted to be operated as a second pole, and a third, isolation layer disposed over said second layer leaving said part of the second layer exposed to the tissue to be ablated, said first pole being adapted for connection to a high frequency energy source for allowing electrical current to pass from said first pole to said second pole through said tissue, and said cryo component adapted for being connected to a cryo energy source for cooling said tissue, said current being lower than that required for thermal ablation of the tissue, for thawing the cryoablated tissue.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to understand the invention and to see how it may be carried out in practice, embodiments will now be described, by way of non-limiting examples only, with reference to the accompanying drawings, in which:

Figs. IA to 1C are schematic illustrations of a prior art monopolar probe, prior art system using such probe and prior art bipolar probe, respectively;

Fig. 2 is a schematic illustration of a combined monopolar probe according to one embodiment of the invention;

Fig. 3 is a more detailed schematic illustration of the combined monopolar probe shown in Fig. 2; Fig. 4 is a schematic illustration of a combined monopolar probe according to another embodiment of the invention;

Fig. 5A is a graphic illustration of a conventional method of cryoablation treatment;

Fig. 5B is a graphic illustration of a method of cryoablation treatment according to a still further embodiment of the present invention;

Fig. 6A is a graphic illustration of a combined bipolar probe according to another embodiment of the invention; Fig. 6B is a graphic illustration of a combined bipolar probe according to another embodiment of the invention;

Fig. 7 is a graphic illustration of a setup according to the present invention;

Figs. 8A and 8B are schematic illustrations of other configurations of the setup seen in Fig. 7;

Fig. 9 shows a prior art guiding matrix; and

Fig. 10 is a graphic illustration of a system for tissue ablation according to the invention.

DETAILED DESCRIPTION OF EMBODIMENTS Figs. IA to 1C illustrate schematically a monopolar RF probe 11 having a single pole 11a, return ground plate 14 and a bipolar RF probe 13 having two poles 13a and 13b separated by an insulation 131, generally known in prior art. The probes 11 and 13 have tips 10 and 12, respectively, and are insertable into a tissue during a tissue treatment procedure. The probes further comprise a metal shaft 111 and an insulation 112 that leaves only the tip non insolated and thus enable current flow only from the tip to the surrounding tissue Lines L schematically represent electrical current and an area Al schematically represents the ablation area within the tissue surrounding the tips 10 and 12 of the probes 11 and 13, respectively.

Fig. IB generally shows a system used for tissue ablation of a patient P by the monopolar probe 11, the system comprising an electrosurgical generator 15 and a return ground plate 14 for supporting the patient. The electrical current 17 (shown by arrows) flows from the electrosurgical generator 15 through the monopolar probe 11 to a tissue of the patient P, and further through the patient's body to the return ground plate 14.

When the bipolar RF probe 13 shown in Fig. 1C is inserted in the tissue of a patient (not shown), the current L flows from the first pole 13a to the second pole 13b through the tissue therebetween.

It should be mentioned that two monopolar probes, such as the described probe 11 may also act as a dipole, so as the current flows from one probe to the other.

With reference to Fig. 2, there is schematically illustrated a combined monopolar probe 21 according to one example of the present invention, in the form of a housing 22 having an electrically-isolated section 27, a non-isolated section 29 with a tip 25, constituting a single pole 21a of the probe and a cryogen tube 23 within the housing whose distal end is disposed adjacent the tip 25.

In operation, the metal housing 22a is connected to an RF source (not shown) providing RF power to the pole 21a, and the cryogen tube 23 is connected to a cryogen source (not shown) for cooling the tip 25. The insulation 22b leaves only the tip non insolated and thus enable current flow only from the tip to the surrounding tissue.

The tip 25 cooled by the cryogen tube 23 (that may comprises a heat exchanging configuration , as shown in Fig. 3) cools the tissue to temperatures higher than those required for cryoablation of the tissue, but sufficient to increase the impedance of its area Al, which causes the electrical current to flow around the cooled area Al, to heat the area A2 of the tissue, surrounding the area Al, to temperatures allowing RF tissue ablation of the area A2 and eventually tissue coagulation. The RF source and the cryogen source operate simultaneously, thereby causing simultaneously heating and cooling of respective areas A2 and Al of the tissue. In case that the area Al should be ablated in addition to area A2, the ablation may be done by any of the means described in the present invention.

Fig. 3 shows an embodiment of the probe 21 further comprising a heat- exchanger, such as Joule-Thomson (J-T) heat exchanger 31 having an orifice 33, which cools the tip 25 of the probe 21 to temperatures enough to increase the impedance of the tissue but higher than those required for cryoablation of the tissue. The temperature is further reduced by exchanging heat between the low temperature outflow gas 35 that extends from the orifice 33 and the inflow gas 37 that coming from the cryogen source (not shown). The probe may further comprise insulation and flow directing element 24 that forces the outflow to flow away from the probe external surface. The element 24 may further comprise trapped volumes 28 to further increase the insulationThe isolation 39 is very thin (about 50 μm) and thus is adapted to provide RF isolation and at the same time allows heat transfer therethrough, Consequently the probe can be used as an independent cryo probe working up to its full power without altering its heat transfer characteristic as a result of the addition of the RF insulation on its housing. . The probe may further comprise electrical heating element 26 and conducting wires 261 to provide further heating of the probe shaft from the probe tip leaving only the probe tip at the cryo low temperature and protecting the shaft surrounding tissue. Fig. 4 shows another configuration of the monopolar combined probe 21. The probe 41 has the same components as the probe 21 previously described, and differs therefrom in the form of its tip 43, having a smaller dimension than the tip 25 of the probe 21, allowing thereby insertion of the probe 41 into small tissue areas and using both energies at the small diameter tip. These probes may further comprise the insulation and flow directing element 24 as shown in figure 3.

The probes 21 and 41 described above may be used in an opposite manner, wherein the tip 25, 43 is cooled to much lower temperatures than those mentioned above for cooling the area Al of the tissue to temperatures required for tissue cryoablation thereof, and the RF energy provided to the pole 21a is used for thawing of the cooled tissue both inside and from its outside, i.e. from the area A2, with temperatures lower than those required for RF tissue ablation.

Fig. 5A shows two freeze-thaw cycles performed by the cryo-cooling of the tissue, followed by the RF-thawing thereof. The time needed for the whole freezing- thawing procedure when RF thawing was used (Fig. 5A) appeared to be shorter than the time it took to complete the procedure when conventional means, e.g. by gas or resistive heating, as illustrated in Fig. 5B. other thawing means (Fig. 5B). The time difference between the two options is represented by Δt. The use of the RF energy for thawing of the cooled tissue as described above reduced the time needed for such thawing compared with thawing by conventional means.

Figs. 6 A and 6B show combined cryo-bipolar probes 61 and 63. Cryo-bipolar probe 61 comprises a first pole 61a by means of the probe metal housing 62, a second pole 611a by means of a thin conductive layer or sheath 611, a thin inner isolation 65 between the poles 61a and 611a and a thin outer isolation 67, both being similar to the isolation 39 described above, a cryogen tube 60 and a J-T heat exchanger 69 similar to the previously described heat-exchanger 31. The isolations 65 and 67 surround the probe 61 leaving only the poles 61a and 611a non-isolated, allowing creating electrical field therebetween. Fig. 6B shows the probe 63 which is a modification to probe 61 wherein isolations 68 and 64 are adapted for sliding over the probe 63 and changing the location and the size of non-isolated segments 63a and 631a, thereby effecting the electrical field and the thawing area of the tissue caused by heat created by said field. These probes may further comprise the insulation and flow directing element 24 as shown in Fig. 3. The cryo-bipolar probes 61,63 provides a continuous mechanical structure and structurally continuous housing 62 that stands with the internal high pressure that is formed by the gases during the cryo cooling phase.

Fig. 7 shows a setup 71 for tissue ablation comprising two monopolar probes 73 having poles 73a and a cryopobe 75 having a tip 77. The monopolar RF probes 73 further comprise isolations 74 leaving only segments 76 of the poles 73 a non-isolated, thereby allowing the poles 73a to constitute a dipole therebetween. The tip 77 is located between the non-isolated segments 76 and cools the tissue so as a cooled area Al has greater impedance than its surrounding area. The electrical current 78 is then forced to flow around the cooled area Al increasing thereby the ablation area A3. The described configuration further referred to as enhanced triplet (RF dipole and one cryo probe therebetween). The RF probes 73 may have a structure similar to any of the monopolar probes described above, and the cryoprobe 75 may be similar to the described cryoprobes which are not intended for cryoablation of the tissue, but only for cooling thereof.

The setup 71 may comprise more than two RF probes and more than one cryoprobe in any configuration thereof. A number and a configuration of said probes are determined according to a size and a shape of a tissue area to be ablated. Moreover, the probes may work on the same energy source, e.g. all the probes are monopolar or bipolar RF probes or cryo probes, so as to allow flexible use to effectively plan and optimize the coverage and ablation of a tumor.

Figs. 8 A and 8B illustrate some possible configurations of the setup 71. Fig. 8 A shows a tumor cross section area T covered by probes 81 (shown by their cross section) having the same energy source, RF or cryo. The tissue within the tumor area is treated only in ablations areas A4 created by these probes. Rest of the area A5 is not effectively treated. Fig. 8B shows another configuration of the setup 71, providing more efficient coverage of the tumor area T by enhanced triplets formed with cryo probes 83 and RF probes 85. Areas A6 are cooled by probes activated as cryo probes to increase the impedance thereof, thereby increasing the treatment areas A7 and providing a better coverage of the tumor area T, than the configuration shown in Fig. 8 A with smaller number of probes.

The positioning of the probes 73 (used as RF probes) and the probes 75 (used as cryo probes) is performed using a guiding matrix for example such as shown in Fig.9. The use of such matrix 90 is known in the art and one example of the known matrix is that used in the system of Endocare, Inc., , Irvine, CA 92618, having a plurality of apertures 91 each adapted for guiding one of the probes 93 therethrough, allowing them to be arranged in a desired configuration. It should be noted that each of the probes discussed above 21, 41, 61, 63 and 73 may be used for conventional tissue treatment. For example, bipolar RF probes can be used as monopolar RF probes, if only one of the poles is activated and the system is equipped with a return ground plate. The cryo probes may be used as the RF probes if the probe shaft is connected to RF source instead of the cryo source, and vice versa. In addition, the probes may function differently during the same treatment process. The same probe may first act as cryo probe and then as RF monopolar or bipolar probe.

It should be also noted that the J-T heat exchanger is especially effective in cases when cryoablation of the tissue is performed and the desired temperature are very low. When the cryo source is not intended for cryoablation, but only for cooling of the tissue, heat exchangers of other configurations may be used as well.

Fig. 10 illustrates a system for tissue ablation 101, the system comprising a high frequency module 103, such as RF generator, microwave, or laser, DC current or warming water; Cryo cooling module 105 of high pressure fluid , such as Argon, CO₂, N₂O, LN₂ etc.; a main control module 107; a user interface 100; a screen 102; energy and feedback wires or fluid tubes 109 connectable at their distal end 109a to probes of any kind described above. The cryo cooling module is connectable to high pressure gas cylinders/LN2 source and the RF module is connectable to standard electrical input (120-240V). The cryo cooling module may comprise electro-mechanical gas valves, pressure transducers, over-pressure safety valves and safety diaphragms, and high pressure connectors both for supply of high pressure gases and delivery of the regulated pressure gases into the probes. Both modules are controlled via a main electronic board that transfers operational signals and receives status and measurements via sensors distributed over the system.

The system 101 may further comprise a man machine interface (MMI), which is a part of the Control module, allowing performance of operations such as: starting and stopping of the procedure

- gathering pre-treatment and treatment data

- presenting real time status (such as gas pressure, RF power, etc.) presenting real time ablation data (RF probes impedance, tips temperature, procedure elapsed time, etc.) saving the system memory and presenting the procedure treatment data

The system may further comprise sensors such as: - feedback sensors for heating and cooling ablation, such as thermocouples located close to the tips of the probes or temperature sensors that are inserted into the tissue as separate needles and indicate the local temperature as a measure for efficacy or safety, for example Multi-Point sensors (MTS™), provided with Prelce™ cryablation system, Galil Medical Ltd, Yokneam, Israel. - gas pressure transducers that are embedded within the cryo cooling module and provide data as for the efficacy of the treatment as well. RP impedance that is measured over the RP probe in order to provide more data to the users. This type of measurements are associated with lower and upper limits that are set within the system decision logic for either warning the users or stopping the procedure.

Claims

CLAIMS:

1. A device for tissue ablation at least by high frequency energy comprising at least one group of probes, each group including: a couple of high frequency probes having a single pole and being adapted for individual disposition of said pole adjacent said tissue at a desired distance from the pole of the other probe, the poles constituting a dipole adapted to apply said energy to a first volume of said tissue; and at least one cryo probe having a cryo tip and adapted for the disposition of the cryo tip between said poles, for cooling said tissue, inducing ablation of a second volume of said tissue which is greater than said first volume.

2. A device according to Claim 1, wherein said cryo probe is adapted for cooling the tissue to be ablated to a temperature higher than that required for cryoablation of the tissue, thereby increasing the electrical resistance of said tissue without ablating thereof.

3. A device according to Claim 1, comprising a plurality of the groups of probes.

4. A device according to Claim 3, wherein at least one of said high frequency probes constitutes a part of said couple of high frequency probes in more than one of said groups.

5. A device according to Claim 4, further comprising a guiding matrix having a plurality of apertures each adapted for guiding one probe therethrough, the apertures being arranged in a pattern allowing different dispositions of the high frequency and cryo probes to form a plurality of the groups of probes in accordance with a desired volume to which said energy is to be applied.

6. A device according to Claim 1, wherein said cryo probe is adapted for being connected to a cryo energy source.

7. A device according to Claim 6, further comprising a cryo energy source, to which a plurality of cryo probes may be connected simultaneously.

8. A device according to Claim 1, wherein said high frequency probes further comprise a high frequency isolation.

9. A device according to Claim 1, wherein the high frequency energy is RF energy.

10. A device according to Claim 1, further comprising a control system.

11. A device according to Claim 10, wherein the control system is adaptable of controlling one or more of the following parameters operation parameters of the device: time of starting and stopping tissue ablation procedure, cryo gas pressure, high frequency power, high frequency impedance, and temperature of tips of the probes.

12. A device according to Claim 1, further comprising one or more feedback sensors.

13. A device according to Claim 12, wherein the feedback sensors are indicative of tissue temperature.

14. A device according to Claim 16, wherein the sensors are in a form of needles insertable into a tissue for measuring local temperature thereof.

15. A device according to Claim 16, wherein the feedback sensors are indicative of high frequency impedance.

16. A device according to Claim 1, where the cryoprobe further comprising a Joule- Thomson heat exchanger.

17. A method for tissue ablation at least by high frequency energy, the method comprising:

- providing at least one couple of high frequency probes each having a single pole, and at least one cryo probe having a cryo tip;

- individually introducing each of said high frequency probes to dispose their poles at a desired distance from each other, to form a dipole suitable for applying said energy to a first volume of said tissue; introducing the cryo tip between said poles for cooling said tissue, to ablate a second volume of said tissue which is greater than said first volume.

18. A method according to Claim 17, further comprising cooling the tissue to be ablated to a temperature higher than that required for cryoablation of the tissue, thereby increasing the electrical resistance of said tissue without ablating thereof.

19. A method according to Claim 18, wherein said cooling is performed by the cryo tip of said probe.

20. A method according to Claim 17, further comprising providing a plurality of the groups of probes.

21. A method according to Claim 20, wherein at least one of said high frequency probes constitutes a part of said couple of high frequency probes in more than one of said groups.

22. A method according to Claim 17, further comprising guiding of said high frequency and cryo probes through a guiding matrix having a plurality of apertures each adapted for guiding one probe therethrough, the apertures being arranged in a pattern allowing different dispositions of the high frequency and cryo probes to form a plurality of the groups of probes in accordance with a desired volume to which said energy is to be applied.

23. A method according to Claim 17, wherein said high frequency probes are adapted for being connected to one and the same high frequency energy source.

24. A method according to Claim 17, further comprising providing said high frequency energy source constituting a part of said device.

25. A method according to Claim 24, wherein at least a part of said high frequency probes are connectable to said source simultaneously.

26. A method according to Claim 17, wherein said cryo probe is adapted for being connected to a cryo energy source.

27. A method according to Claim 17, further comprising providing a cryo energy source, to which a plurality of cryo probes may be connected simultaneously.

28. A method according to Claim 17, wherein said high frequency probe comprises a high frequency isolation.

29. A method according to Claim 28, wherein said isolation allows heat transfer therethrough.

30. A method according to Claim 17, wherein the high frequency energy is RF energy.

31. A method according to Claim 17, further comprising controlling of one or more of the following parameters: times of starting and stopping of a tissue ablation procedure, cryo gas pressure, cryo valve status, high frequency power, high frequency impedance, temperature of tips of the probes.

32. A method according to Claim 17, further comprising providing one or more feedback sensors.

33. A method according to Claim 32, wherein the feedback sensors are indicative of tissue temperature.

34. A method according to Claim 33, wherein the sensors are in a form of needles inserted into a tissue for measuring a local temperature thereof.

35. A method according to Claim 33, wherein the feedback sensors are indicative of high frequency impedance.

36. A method according to Claim 17, further comprising providing a Joule-Thomson heat exchanger to the cryoprobe .

37. A monopolar probe for thermal ablation of a tissue by applying to the tissue of high frequency energy, having a single pole adapted for being connected to a high frequency energy source for allowing electrical current to pass through said tissue, and a cryo component adapted for being connected to a cryo energy source for cooling the tissue to be ablated to a temperature higher than that required for cryoablation of the tissue, thereby increasing the volume ablated by said high frequency energy.

38. A probe according to claim 37, wherein said cryo energy source is adapted to provide such cryo energy thereto as to cool the tissue to a temperature is lower than that required for cryoablation of the tissue.

39. A probe according to claim 37, wherein the high frequency energy source and the cryo energy source are operatable simultaneously for thermal ablation and cooling of the tissue, respectively.

40. A probe according to claim 37, the cryo component is embedded within the probe.

41. A probe according to claim 37, further comprising a Joule-Thomson heat exchanger.

42. A probe according to claim 37, further comprising a high frequency isolation.

43. A probe according to claim 37, wherein the high frequency energy is RF energy.

44. A method for thermal ablation of a tissue by applying to the tissue of high frequency energy, the method comprising:

- providing a monopolar probe having a single pole adapted for being connected to a high frequency energy source for allowing electrical current to pass through said tissue; - providing a cryo component adapted for being connected to a cryo energy source for cooling the tissue to be ablated to a temperature higher than that required for cryoablation of the tissue, thereby increasing the volume ablated by said high frequency energy.

45. A method according to claim 44, providing such cryo energy for cooling the tissue to a temperature is lower than that required for cryoablation of the tissue.

46. A method according to claim 44, wherein the high frequency energy source and the cryo energy source are operating simultaneously for thermal ablation and cooling of the tissue, respectively.

47. A method according to claim 44, wherein the cryo component is embedded within said probe.

48. A method according to claim 44, further comprising providing a Joule-Thomson heat exchanger.

49. A method according to claim 44, further comprising providing said probe with a high frequency isolation.

50. A method according to claim 49, wherein said isolation allows heat transfer therethrough.

51. A method according to claim 44, wherein the high frequency energy is RP energy.

52. A probe for cryoablation of a tissue by applying to the tissue of cryo energy, having a cryo component adapted for being connected to a cryo energy source for cooling the tissue to a temperature required for cryoablation thereof, and high frequency energy electrode assembly adapted for being connected to a high frequency energy source to allow passing through said tissue of high frequency current lower than that required for thermal ablation of tissue, for thawing the cooled tissue.

53. A probe according to claim 52, further comprising a Joule-Thomson heat exchanger.

54. A probe according to claim 52, further comprising a high frequency isolation.

55. A method for cryoablation of a tissue by applying to the tissue of cryo energy, comprising applying to the tissue of at least one cryablation cycle, the cycle comprising:

- applying cryo energy to the tissue for a first time interval, and thereby cooling the tissue to a temperature required for cryoablation thereof; and

- subsequently applying to the cryoablated tissue for a second time interval of high frequency energy lower than that required for thermal ablation of tissue, thereby thawing the cooled tissue.

56. A method according to Claim 55, further comprising providing a probe for applying to the tissue of said cryo energy and said high frequency energy.

57. A method according to Claim 56, further comprising providing a cryo energy source and a high frequency energy source and connecting said probe to these sources at least during said first and second time intervals.

58. A method according to Claim 55, wherein said cryo energy is applied by a first probe and said high frequency energy is applied by a second probe.

59. A method according to Claim 55, comprising applying to the tissue of more than one cryablation cycle.

60. A system for tissue ablation comprising one or more probes, a cryo source adapted to provide to at least one of said probes first cryo energy required for cryo ablation of said tissue and adapted to provide to at least one of said probes second cryo energy for cooling the tissue to be ablated to a temperature higher than that required for cryoablation; a high energy source adapted to provide to at least one of said probes first high frequency energy required for thermal ablation of said tissue and adapted to provide to at least one of said probes second high frequency energy lower than that required for thermal ablation of the tissue; and a control module to control the activation of said one or more probes by controlling the application thereto of one or more of the following: the first cry energy, the second cryo energy, the first high frequency energy and the second high frequency energy.

61. A system according to Claim 60, wherein at least one of the probes is adapted for applying thereto said first high frequency energy and said second cryo energy.

62. A system according to Claim 60, wherein at least one of the probes is adapted for applying thereto said first cryo energy and said second high frequency energy.

63. A system according to Claim 60, further comprising man machine interface module.

64. A system for tissue ablation according to Claim 60, further comprising an imaging facility to help the physician inserting the probes and follow on with the ablation process.

65. A bipolar probe for tissue ablation comprising a housing with a cryo component, at least a part of said housing being adapted to be operated as a first pole, a first, isolation layer disposed over said housing leaving said part of the housing exposed to the tissue to be ablated, a second, conductive layer disposed over the first isolation layer, at least a portion of which is adapted to be operated as a second pole, and a third, isolation layer disposed over said second layer leaving said part of the second layer exposed to the tissue to be ablated, said first pole being adapted for connection to a high frequency energy source for allowing electrical current to pass from said first pole to said second pole through said tissue, and said cryo component adapted for being connected to a cryo energy source for cooling said tissue.

66. A probe according to Claim 65, wherein said current is equal to that required for thermal ablation of the tissue.

67. A probe according to Claim 66, wherein said cryo energy source is adapted to provide said probe with a cryo energy for cooling the tissue to a temperature higher than that required for cryoablation of the tissue.

68. A probe according to Claim 65, wherein said current is lower than that required for thermal ablation of the tissue.

69. A probe according to Claim 68, wherein said cryo energy source is adapted to provide said probe with a cryo energy required for cryo ablation of the tissue.

70. A probe according to Claim 65, wherein said isolation layers are adapted for sliding over said probe, for the exposure of said first and second poles to the tissue to be ablated.

71. A probe according to Claim 65, wherein said layers are concentric with said housing.

72. A bipolar probe for thermal ablation of a tissue comprising a housing with a cryo component, at least a part of said housing being adapted to be operated as a first pole, a first, isolation layer disposed over said housing leaving said part of the housing exposed to the tissue to be ablated, a second, conductive layer disposed over the first isolation layer, at least a portion of which is adapted to be operated as a second pole, and a third, isolation layer disposed over said second layer leaving said part of the second layer exposed to the tissue to be ablated, said first pole being adapted for connection to a high frequency energy source for allowing electrical current to pass from said first pole to said second pole through said tissue, and said cryo component adapted for being connected to a cryo energy source for cooling said tissue to a temperature higher than that required for cryoablation of the tissue, thereby increasing the volume ablated by said high frequency energy.

73. A bipolar probe for cryoablation ablation of a tissue comprising a housing with a cryo component, at least a part of said housing being adapted to be operated as a first pole, a first, isolation layer disposed over said housing leaving said part of the housing exposed to the tissue to be ablated, a second, conductive layer disposed over the first isolation layer, at least a portion of which is adapted to be operated as a second pole, and a third, isolation layer disposed over said second layer leaving said part of the second layer exposed to the tissue to be ablated, said first pole being adapted for connection to a high frequency energy source for allowing electrical current to pass from said first pole to said second pole through said tissue, and said cryo component adapted for being connected to a cryo energy source for cooling said tissue, said current being lower than that required for thermal ablation of the tissue, for thawing the cryoablated tissue.