Systems for determining ablation score and for pre-ablation testing

Abstract

To provide tissue ablation devices and methods of use that reduce undesirable medical complications and achieve desired ablation of target tissue.SOLUTION: Various aspects of the present invention are directed towards apparatuses, systems and methods that may include a tissue ablation system. The tissue ablation system may include an ablation device 120, an ablation generator, and a controller 106 configured to initiate a pre-ablation procedure in a medium and, during the pre-ablation procedure, monitor temperature data and / or power data.SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] The present invention relates to tissue ablation instruments and methods of use. [Background technology]

[0002] In the treatment of diseases such as cancer, it has been found that certain types of tissue are denatured by heat. This type of treatment, commonly referred to as hyperthermia, typically uses electromagnetic radiation to heat cancerous tissue to temperatures above 60°C, while healthy tissue is kept at a lower temperature to avoid irreversible cell destruction. Microwave ablation is one such treatment that uses electromagnetic radiation to heat tissue.

[0003] Microwave tissue ablation is a less invasive procedure than surgical resection and in many situations tumors may be difficult to remove surgically, for example when the tumor is relatively small, located near a relatively small organ, or located near a large blood vessel. This approach has been employed in organs where surgical removal of tumors may be difficult, such as the prostate, heart, and liver.

[0004] In order to effectively plan and optimize a procedure, it is desirable for an ablation instrument to have an ablation volume of predictable size and shape. For this reason, predictable ablation volumes having regular shapes are preferred, and creating spherical or nearly spherical ablation volumes is particularly preferred. Ablation instruments with ablation volumes of predictable size and shape facilitate surgical procedures and reduce undesirable medical complications.

[0005] It is also desirable that the ablation procedure be performed efficiently and that the ablation instrument perform predictably during the procedure to reduce undesirable medical complications and achieve the desired ablation of the target tissue. Summary of the Invention [Means for solving the problem]

[0006] In Example 1, the tissue ablation system includes an ablation device configured to apply energy to a target area, an ablation generator configured to supply power to the ablation device, and a controller in communication with the ablation generator and configured to initiate a pre-ablation treatment in a medium prior to an ablation procedure, wherein during the pre-ablation treatment, the controller is configured to cause the ablation generator to supply power to the ablation device, monitor temperature data, monitor power data representative of power supplied to the ablation device, and identify a status of the ablation device based on the monitored temperature data and the monitored power data.

[0007] In Example 2, in the system of Example 1, the power delivered to the ablation tool is between 1 and 20 watts. In Example 3, in the system of Examples 1 or 2, the pre-ablation treatment includes delivering power to the ablation tool for 5 to 30 seconds.

[0008] In Example 4, in the system of any one of Examples 1 to 3, the medium is a tissue simulator. In Example 5, in the system of any one of Examples 1 to 3, the medium is sterile water.

[0009] In Example 6, in the system of any one of Examples 1 to 3, the medium is tissue undergoing an ablation procedure. In Example 7, the system of any one of Examples 1-6, the controller is further configured to supply a coolant to the ablation device.

[0010] In Example 8, in the system of Example 7, the temperature data monitored is the temperature of the coolant. In Example 9, in the system of any one of Examples 1-6, the temperature data monitored is the temperature of the medium surrounding the ablation device.

[0011] In Example 10, in the system of any one of Examples 1 to 9, the monitored temperature data is the temperature of the ablation tool. In Example 11, in the system of any one of Examples 1 to 10, the controller is further configured to perform an ablation procedure.

[0012] In Example 12, the system of any one of Examples 1-11, wherein the ablation tool includes a microwave ablation needle. In Example 13, the system of any one of Examples 1 to 12 further includes a user interface configured to receive an input related to a pre-ablation procedure.

[0013] In Example 14, the system of any one of Examples 1 to 13 further includes a user interface configured to receive input related to the ablation procedure. In Example 15, the system of any one of Examples 1-14 further includes a second ablation instrument configured to apply energy to the target region.

[0014] In Example 16, a method of preparing an ablation device for an ablation procedure includes inserting the ablation device into a medium; initiating a pre-ablation treatment prior to the ablation procedure, the pre-ablation treatment including causing an ablation generator to supply power to the ablation device; monitoring temperature data; monitoring power data representative of power supplied to the ablation device; and determining a status of the ablation device based on the temperature data and the power data.

[0015] In Example 17, the method of Example 16, wherein the power delivered to the ablation device is between 1 and 20 watts. In example 18, the method of example 16, the pre-ablation treatment comprises delivering power to the ablation device for 5 to 30 seconds.

[0016] In Example 19, the method of Example 16 further comprises determining a power efficiency of the ablation tool. In Example 20, the method of Example 16, wherein the medium is sterile water.

[0017] In Example 21, the method of Example 16, wherein the medium is tissue undergoing ablation. In Example 22, the method of Example 16 further comprises providing a coolant to the ablation device.

[0018] In Example 23, the method of Example 17, wherein the monitored temperature data is a coolant temperature. In Example 24, the method of Example 16, wherein the temperature data monitored is the temperature of the medium surrounding the ablation device.

[0019] In Example 25, the method of Example 16, wherein the monitored temperature data is the temperature of the ablation tool. In Example 26, the method of Example 16 further comprises performing an ablation procedure.

[0020] In Example 27, a method of preparing an ablation device for an ablation procedure includes inserting the ablation device into a medium; initiating a pre-ablation treatment prior to the ablation procedure, the pre-ablation treatment including causing a coolant pump to deliver coolant to the ablation device; causing an ablation generator to supply power to the ablation device; monitoring the temperature of the coolant; monitoring power data representative of the power supplied to the ablation device; and determining a status of the ablation device based on the monitored temperature data and the monitored power data.

[0021] In Example 28, the method of Example 27, wherein the power delivered to the ablation device is between 1 and 20 watts. In example 29, the method of example 27, the pre-ablation treatment comprises delivering power to the ablation device for 5 to 30 seconds.

[0022] In Example 30, the method of Example 27 further comprises determining a power efficiency of the ablation tool. In Example 31, the method of Example 27, wherein the medium is sterile water.

[0023] In Example 32, the method of Example 27, wherein the medium is tissue undergoing ablation. In Example 33, the method of Example 27, wherein the monitored temperature data is the temperature of the medium surrounding the ablation device.

[0024] In Example 34, the method of Example 27 further comprises performing an ablation procedure. In Example 35, the tissue ablation system includes an ablation device configured to apply energy to a target area, an ablation generator configured to supply power to the ablation device, and a controller in communication with the ablation generator and configured to initiate a pre-ablation treatment prior to the ablation procedure, wherein during the pre-ablation treatment, the controller is configured to cause a coolant pump to deliver coolant to the ablation device, cause the ablation generator to supply power to the ablation device, monitor a temperature of the coolant, monitor power data representative of the power supplied to the ablation device, and determine a status of the ablation device based on the monitored temperature data and the monitored power data.

[0025] While several embodiments are disclosed, still other embodiments of the subject matter disclosed herein can be understood by those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the disclosed subject matter. Accordingly, the drawings and detailed description are to be regarded as illustrative and not restrictive.

[0026] Advantages of the present invention may become apparent to those skilled in the art from the following detailed description and by reference to the accompanying drawings. [Brief description of the drawings]

[0027] [Figure 1A] 1 is a block diagram including elements of a system for performing an ablation process, according to one embodiment of the present invention. [Figure 1B] FIG. 2 is a block diagram illustrating the operation of an ablation instrument interface for connecting with an ablation instrument to perform an ablation process, according to one embodiment of the present invention. [Diagram 2] 1 is a simplified schematic diagram illustrating a cooling system according to the present invention. [Diagram 3] 1 is a perspective view of a microwave tissue ablation instrument with a handle, according to one embodiment of the present invention. [Figure 4A] 1 is a perspective view of a microwave tissue ablation instrument 400 according to one embodiment of the present invention. [Figure 4B] FIG. 2 is a cross-sectional view taken along line XY illustrating one embodiment of a cooling mechanism. [Diagram 5] 1 is a side view of a microwave tissue ablation instrument according to one embodiment of the present invention. [Figure 6A] FIG. 2 is a plan view showing a configuration of multiple microwave tissue ablation needles. [Figure 6B] FIG. 13 is a front view showing multiple ablation tools at different depth placements. [Figure 7] FIG. 2 is a block diagram illustrating details of an exemplary pre-ablation procedure. [Figure 8] FIG. 1 is a block diagram illustrating details of an exemplary ablation procedure. [Figure 9] A diagram showing a GUI that can be used for ablation procedures. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] The size and dimensions of the ablation region created by a microwave tissue ablation instrument are based on, among other factors, the type of microwave antenna. A clinician may select a microwave antenna capable of producing an ablation region larger than the size and dimensions of the target tissue, and insert the microwave antenna such that the ablation region created by the microwave antenna includes the target tissue. If the tissue to be ablated is larger than the size of the ablation volume created by the instrument, multiple instruments may be used to combine the ablation volumes to cover the tissue to be ablated. The microwave tissue ablation instrument embodiments described herein may be used to create ablation regions of predictable shape with reduced tailing, which aids in ablation planning and prevents damage to tissue outside the treatment volume.

[0029] In some embodiments, the ablation instruments disclosed herein are microwave ablation instruments configured to perform ablation by emission of microwave energy that heats and necrotizes tissue. Typically, the instrument is a microwave ablation needle having a microwave antenna, such as those described herein.

[0030] In another aspect, the invention provides a system for microwave ablation of tissue including one or more microwave ablation instruments, such as a probe or needle described herein, including a microwave antenna configured to transmit microwave energy to tissue, a microwave generator configured to supply microwave energy to the microwave antenna via a feedline, and one or more power cables configured to connect the microwave generator to the microwave antenna of the ablation instrument and deliver microwave energy applied by the microwave generator to the antenna for ablation of tissue.

[0031] Ablation instruments such as those described herein can be configured to operate at up to 150 watts of power for periods of up to 20 minutes or more. During use, the instrument heats up due to resistive heating of the antenna and energy reflected from the tissue, and generally requires cooling of at least the distal portion of the instrument, including the distal portion of the feedline and the antenna. Preferably, in various embodiments, the feedline and antenna are entirely cooled. Cooling the antenna prevents damage to the instrument itself and prevents overheating or burning of tissue proximate to the antenna. This can change the physical properties of the tissue, such as energy absorption and reflection characteristics, and thus reduce the efficiency of the antenna and alter the ablation area. Thus, in certain embodiments, the tissue ablation instrument can additionally include a cooling system for cooling at least a portion of the antenna and / or feedline. Such a cooling system is generally configured to pass a cooling fluid, such as a coolant (e.g., water), through at least a portion of the feedline and the antenna. Typically, such systems include a coolant inlet and a coolant outlet that cooperate to allow coolant to pass through the antenna and optionally at least a portion of the feedline to cool at least a portion, and preferably all, of the antenna and optionally the feedline, which are typically in contact with the coolant.

[0032] As one option, the cooling system includes a coolant chamber surrounding the antenna and at least a distal portion of the feed line and having a coolant inlet conduit configured to supply coolant to the coolant chamber and a coolant outlet conduit configured to pass the coolant from the coolant chamber, the coolant inlet conduit and the coolant outlet conduit configured to pass the coolant through at least a portion of the feed line and at least a portion of the antenna.

[0033] 1A illustrates a block diagram including elements of a system for performing an ablation process, according to one embodiment of the present invention. The system includes a console 102, which includes a user interface 104, a controller 106, and an ablation tool interface 108. In one embodiment, the user interface 104 includes a display for presenting information to a user and an input device for receiving input from the user, for example, via one or more buttons, dials, switches, or other operable elements. In one embodiment, the user interface 104 includes a touch screen display that functions as both the display and the input device for the user interface 104.

[0034] According to certain aspects of the invention, the ablation instrument interface 108 of the console 102 is configured to connect to one or more ablation instruments. In the embodiment of FIG. 1A, the ablation instrument interface 108 connects to three ablation instruments 120a, 120b, 120c via lines 110a, 110b, 110c, respectively. In certain embodiments, the console 102 can connect to one, two, or all three ablation instruments (120a, 120b, 120c) individually or simultaneously. Although three ablation instruments are shown in the embodiment of FIG. 1A, various aspects of the invention may include consoles having ablation instrument interfaces that can connect to other numbers of ablation instruments.

[0035] In some embodiments, the console includes an ablation device interface that can connect to one ablation device. In other embodiments, the console includes an ablation device interface that can connect to two ablation devices, three ablation devices, four ablation devices, or five ablation devices. In some examples, the ablation device interface can be configured to connect to any number of ablation devices.

[0036] According to certain aspects of the invention, a console may be used to operate any number of ablation devices, up to the number of ablation devices supported by the ablation device interface. For example, a console having an ablation device interface capable of simultaneously accepting three ablation devices may be configured to operate one, two, or three ablation devices.

[0037] In one embodiment, lines 110a, 110b, 110c are configured to supply coolant (e.g., from coolant source 140) and ablation power (e.g., a microwave signal) to ablation devices 120a, 120b, 120c, respectively. Lines 110a, 110b, 110c can be configured to provide a path for coolant to be supplied to the respective ablation devices and a return path for receiving coolant from the respective ablation devices after passing through coolant flow paths within the ablation devices.

[0038] According to certain aspects of the present invention, controller 106 is configured to couple to user interface 104 and ablation device interface 108. In certain embodiments, controller 106 can be configured to receive one or more inputs via user interface 104 and output one or more items via user interface 104.

[0039] The controller 106 can be configured to control the operation of one or more ablation instruments (e.g., 120a, 120b, 120c) via the ablation instrument interface 108. In an embodiment, the controller 106 can cause a coolant to be provided to one or more ablation instruments via the ablation instrument interface 108. The controller 106 can cause ablation power to be provided to the one or more ablation instruments to cause the ablation instruments to perform an ablation process. In an embodiment, the ablation power provided to the ablation instruments causes the microwave ablation instruments to emit microwave radiation. The power source 130 can provide the power used to generate the ablation power.

[0040] In one example, the controller includes one or more processors and a memory that stores instructions for the one or more processors to execute via the controller. In some embodiments of the present invention, the controller is implemented as one or more processors, such as, for example, one or more microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or programmable logic circuits, alone or in any suitable combination. The controller may also include a memory that stores program instructions and associated data that, when executed, cause the controller to perform the functions ascribed to the controller in this disclosure. The memory may also include any fixed or removable magnetic, optical, or electrical medium, such as, for example, RAM, ROM, CD-ROM, flash memory, or EEPROM. The memory may also include a removable memory portion that may be used to update or increase the capacity of the memory. The removable memory may also allow image data to be easily transferred to other computing devices. The controller may also be implemented as a system-on-chip that integrates some or all elements of a computer or other electronic system into one chip.

[0041] FIG. 1B shows a block diagram illustrating the operation of an ablation instrument interface to connect to an ablation instrument to perform an ablation process, according to one embodiment of the present invention. In one example, the ablation instrument interface 108 includes one or more fluid pumps (148a, 148b, 148c) each configured to deliver coolant to a respective ablation instrument. For example, as shown, pump 148a can be in communication with a coolant source 140 and configured to deliver coolant to the ablation instrument (e.g., 120a) via coolant line 114a. Such pumps can be controlled by a controller. The controller can be configured to control the flow rate of fluid delivered from the pump (e.g., 148a) to the ablation instrument (e.g., 120a), including starting and stopping the pump from delivering coolant to the ablation instrument.

[0042] In the example of Figure 1B, the ablation instrument interface 108 includes three pumps 148a, 148b, 148c for supplying coolant to each ablation instrument via coolant lines 114a, 114b, 114c, respectively. The coolant lines 114a, 114b, 114c may be included within the lines 110a, 110b, 110c, respectively, shown in Figure 1A. In one embodiment, each pump is controlled by a controller, e.g., independently of the other pumps, such that any pump may operate regardless of the operating state of the other pumps.

[0043] In other embodiments, pumps 148a, 148b, 148c each include a peristaltic pump driven by a single motor controlled by a controller. In some such examples, each pump operates at the same speed as determined by the motor, and coolant flows through coolant lines 114a, 114b, 114c to any connected ablation devices. By controlling the speed of the motor, the controller can regulate the flow rate of coolant through the ablation device.

[0044] In some instances, the coolant provided to the ablation devices is supplied in a closed loop recirculation system, where coolant is received from the ablation devices and returned to the coolant source 140. In certain embodiments, the coolant source 140 includes a reservoir of coolant, e.g., sterile water, from which the coolant is drawn, delivered via coolant lines to one or more ablation devices, and returned from the one or more ablation devices to the reservoir via a coolant outlet line configured to carry the coolant out of the ablation devices. In some alternative instances, the coolant outlet line carries the coolant away from the ablation devices to a waste system (e.g., to a drain).

[0045] The ablation instrument interface of FIG. 1B includes a microwave generator 138 that generates a microwave signal and supplies it to a microwave antenna in the microwave ablation instrument configured to transmit microwave energy to tissue. Supplying the microwave signal to the ablation instrument can include supplying ablation power to the ablation instrument, which emits microwave radiation. The microwave generator 138 can supply the microwave signal to the ablation instrument via a power cable. In the embodiment of FIG. 1B, the microwave generator 138 can supply microwave signals to up to three ablation instruments via power cables 112a, 112b, 112c, respectively.

[0046] The power cables 112a, 112b, 112c are preferably coaxial cables, which are preferably rated for a power of at least 30 watts, preferably at least 100 watts, preferably at least 150 watts. The cables may be cooled cables configured to be cooled by a coolant supply, preferably by circulating coolant along the cables between a cable coolant inlet and a cable coolant outlet. In some examples, coolant lines 114a-114c supply coolant along the power cables 112a-112c, respectively. In one exemplary configuration, the system includes a cooling system configured to cool both the cables and the microwave ablation instrument.

[0047] In some examples, the microwave generator is preferably configured to provide microwave energy to the antenna in one or more of the 915 MHz band (902-928 MHz), 2.45 GHz band (2.402-2.483 GHz), or 5.8 GHz band (5.725-5.875 GHz) ranges, preferably the 2.45 GHz band, and most preferably at or about 2.45 GHz. The microwave generator may be configured to provide microwave energy to the antennas of up to five microwave ablation probes, preferably one, two, or three probes.

[0048] The microwave generator 138 can be configured to provide a microwave signal as defined by the controller 106. For example, in an exemplary embodiment, the controller 106 can instruct the microwave generator 138 to provide a particular microwave signal to a particular ablation device. The controller can be configured to specify a particular ablation magnitude (e.g., a desired microwave power and / or energy emitted from the ablation device, etc.), ablation duration, or other parameters, such as a duty cycle, phase shift, or other parameters associated with the microwave signal. In some examples, the microwave signal includes a power (e.g., 90 W) to be delivered to the ablation device. The microwave signal can include an electrical signal that includes characteristics (e.g., power, frequency, etc.) for causing the ablation device to emit microwave radiation having desired characteristics (e.g., microwave power emitted to surrounding tissue, etc.). The electrical signal can provide the desired ablation power to the microwave ablation device.

[0049] In some embodiments, the controller 106 can instruct the microwave generator 138 to apply a microwave signal to each of a plurality of ablation instruments. For example, with reference to FIG. 1B, the controller can instruct the microwave generator 138 to provide a first microwave signal to a first ablation instrument via power cable 112a, a second microwave signal to a second ablation instrument via power cable 112b, and a third microwave signal to a third ablation instrument via power cable 112c. In some such examples, the microwave generator 138 can provide such first, second, and third microwave signals simultaneously. Such signals can be the same signal or different signals. For example, in some embodiments, a similar degree of ablation power is provided by each of the first, second, and third microwave signals.

[0050] In some examples, the controller may be configured to control one or more of the following parameters, where the parameters are output wavelength, output power, the duration that microwave energy is delivered to one or more of the antennas, and the duration that energy is delivered at the output power. If the ablation instrument includes a sensor, such as a temperature sensor, the controller may be configured to control any one or more of the parameters in response to a signal (e.g., a temperature measurement) from the sensor. For example, the controller may be configured to turn off power to one or more of the antennas in response to an excessive temperature condition.

[0051] 1B as being implemented as one microwave generator 138 configured to provide microwave signals to multiple ablation instruments, in some examples, the ablation instrument interface 108 can include multiple microwave generators, each corresponding to a respective ablation instrument. In one embodiment, the controller 106 can be connected to the multiple microwave generators and configured to cause the multiple microwave generators to apply microwave signals to respective power cables (e.g., 112a, 112b, 112c) such that such microwave signals are provided to respective ablation instruments.

[0052] 1B illustrates an exemplary embodiment in which three lines 110a, 110b, 110c can provide microwave signals and coolant to each of three ablation instruments simultaneously. In some aspects of the invention, the microwave signals and coolant can be provided to only some of the lines 110a, 110b, 110c, for example, when fewer than three ablation instruments are connected to the console 102. Furthermore, in some aspects, the microwave signals and coolant can be provided to only some of the lines 110a, 110b, 110c, even when three ablation instruments are connected to the console 102. For example, one or more of the ablation instruments so connected can be kept unused.

[0053] In one embodiment, the controller 106 controls which ablation instruments (e.g., which lines of 110a, 110b, 110c) receive the microwave signal and coolant. In one aspect of the invention, the controller 106 can control aspects of the microwave signal, such as the magnitude, frequency, duty cycle, duration, etc. of the microwave signal. In another aspect of the invention, the controller 106 can control the manner in which coolant is supplied to the ablation instruments, such as controlling the operation of the respective pumps to control the flow rate of coolant. In one embodiment, for each ablation instrument, the controller controls the manner in which the microwave signal is applied to the ablation instrument, and the manner in which coolant is supplied to the ablation instrument. In operation, the different ablation instruments can each receive a microwave signal and such amount of coolant is independent of the signal and fluid received at the other ablation instruments, and can be the same or different from the microwave signal and amount of fluid supplied to the other ablation instruments.

[0054] Although FIG. 1B shows ablation device interfaces that connect to three ablation devices, different embodiments of the console can include ablation device interfaces that can connect to other numbers of ablation devices.

[0055] 1B shows ablation device interface 108 including several elements for interfacing with an ablation device, the elements shown to be part of ablation device interface 108 need not necessarily be contained within one module or housing. Such elements are grouped together in the ablation device interface in that they facilitate control by controller 106 of a connected ablation device.

[0056] Additionally, although FIG. 1B illustrates an ablation device interface that connects to a microwave ablation device, the same ablation device interface concept can also be used to form a connection between the controller and other ablation devices, such as RF ablation, or cryoablation, etc.

[0057] In one embodiment, the ablation instrument interface includes one or more ports configured to receive a portion of the ablation instrument, such as a cartridge having a fluid interface for connecting to a fluid line (e.g., 114a) and / or an electrical interface for connecting to a power cable (e.g., 112a).

[0058] 2 is a simplified schematic diagram illustrating a cooling system according to the present invention. The system 201 includes an ablation instrument 202, in this case a microwave ablation instrument including a microwave ablation needle configured to deliver microwave energy to tissue of a patient to ablate the tissue.

[0059] The microwave ablation instrument 202 has a tip 203 configured to pierce tissue and an elongated shaft having a proximal end 205 and a distal end 206. The shaft encloses a coolant chamber 214 and a feedline 207, which may be a coaxial cable having an inner conductor, an outer conductor, and a dielectric therebetween (not shown in FIG. 2). The feedline of FIG. 2 includes a radiating region 208 at its distal end that includes a microwave antenna 204. The proximal end of the feedline 207 is attached to a cable 209 (typically a coaxial cable) for connecting the microwave ablation instrument 202 to a microwave generator 210 to provide microwave energy to the instrument. The cable may be removably connectable or, as in this case, may be permanently attached to the instrument. In some embodiments, as shown with respect to FIG. 1A or 1B, the microwave generator 210 is housed in a console, such as the console 102.

[0060] The instrument is supplied with coolant via an instrument coolant supply line 211, which may be permanently attached to an instrument coolant inlet 212. In some embodiments, the instrument coolant supply line may alternatively be removably connectable to the coolant inlet 212, such as via a Luer® style connector. The instrument coolant inlet 212 communicates with an instrument coolant outlet 213 via a series of coolant passages 214, 215, and 216 configured to circulate the coolant within the instrument. In this simplified diagram, coolant enters the instrument via a coolant inlet tube 215, circulates through a coolant chamber 214 to cool the instrument, and exits through a coolant outlet tube 216 and an instrument coolant return line 217.

[0061] The system 201 includes a manifold 218 that receives coolant fluid from a coolant fluid source 219 via a coolant system supply line 220. The coolant system supply line 220 may be permanently connected to the manifold 218 at a manifold fluid supply inlet 250 or may be removably connected to the supply inlet 250, for example, by a LuerLok® connector. The coolant fluid source may be, for example, an IV bag. Incoming coolant may be distributed to one or more manifold outlet ports 21 via a manifold inlet conduit 222. In a preferred embodiment, as shown in FIG. 2, the flow of coolant out of the port 221 may be controlled by a manifold outlet valve 223, which is normally in a closed position. In some embodiments, as shown with respect to FIG. 1A or 1B, the manifold 218 may be housed within a console, for example, the console 102.

[0062] The manifold 218 also includes a manifold coolant outlet conduit 224 that forms a fluid connection between one or more manifold fluid inlet ports 225 and a coolant system return line 226. The coolant system return line 226 may be permanently connected to the manifold 218 at a manifold fluid return inlet 251 or may be removably connectable to a supply inlet 250, for example, by a LuerLok® connector. In one aspect of the design, a manifold inlet valve 227 controls the flow through each inlet port and may also be normally closed.

[0063] Supply coupling 229 is configured to connect to manifold outlet port 221. The system may also include a return coupling 233, which is configured to connect to the manifold inlet port. In one embodiment, manifold outlet valve 223 may be configured to open when supply coupling 229 is connected. In one approach, supply coupling includes a protrusion 230 that causes the valve to open when coupling 229 is connected to port 221, although other configurations are possible as described elsewhere herein.

[0064] A coolant circuit coolant inlet 231 on the supply coupling 229 communicates with the instrument coolant supply line 211 so that when the supply coupling 229 is connected to the outlet port 221 , the cooling circuit 232 communicates with the cooling fluid source 219 .

[0065] The return coupling 233 may have a coolant circuit outlet 234 that communicates with the instrument coolant return line 217. The supply coupling 229 and the return coupling 233 may be configured to be simultaneously connected to the manifold outlet port 221 and the inlet port 225, respectively.

[0066] The pumping section 235 is configured to be disposed, for example, in the instrument cooling circuit 232 and disposed in the supply line 211 to circulate coolant through the microwave ablation instrument 202. In the system shown in FIG. 2, the pump is a disposable pump head 236 having pump vanes 237 permanently connected in the instrument coolant supply line 211 and adapted to be connected to a pump head drive (not shown). Alternative pumping sections may be used and are described elsewhere herein. In some embodiments, as shown with respect to FIG. 1A or 1B, the pumping section 235 may be housed in a console, for example, the console 102.

[0067] FIG. 3 is a perspective view of a microwave tissue ablation instrument 300 including a handle 305 according to one embodiment of the present invention. The microwave tissue ablation instrument 300 includes a handle 305. The handle 305 is configured to provide a more secure grip for a surgeon to manipulate the tissue ablation instrument 300. The handle 305 is further configured to house a liquid manifold for coolant circulation and a coaxial connector for powering the feed line.

[0068] The microwave tissue ablation instrument 300 includes a probe 307. The probe 307 is configured to be inserted into a patient's body to heat the target tissue. In one embodiment, the probe 307 includes various ablation instrument elements described elsewhere herein, such as a feedline, an asymmetric dipole antenna, a cooling system with inlet and outlet tubes, etc. In one embodiment, the microwave antenna is configured to emit microwave radiation in a frequency band selected from the 915 MHz band (902-928 MHz), the 2.45 GHz band (2.402-2.483 GHz), and / or the 5.8 GHz band (5.725-5.875 GHz). The preferred wavelengths are within the 2.45 GHz band, and in particular, the antenna is preferably configured to emit microwave energy at or about 2.45 GHz. The instrument is configured to operate with up to 150 watts of power provided to the antenna.

[0069] The probe 307 includes a surface 315 configured to contact body tissue and formed of a biocompatible material. The shaft of the instrument is at least partially metallic, such as stainless steel, and includes a marking 311, such as a laser marking. The marking 311 is configured to inform the surgeon of the penetration depth of the probe into the body. It may include a lubricious surface layer, such as PTFE, to aid insertion and prevent tissue from adhering to the needle shaft during insertion or removal of the needle.

[0070] The shaft is generally cylindrical and is generally made of a biocompatible polymer, a biocompatible composite material, such as a glass or carbon fiber reinforced polymer, a ceramic, or a metal, such as stainless steel. The shaft is preferably made of a ceramic or a metal, although in preferred embodiments the shaft includes a metallic portion and a non-metallic portion. The non-metallic portion may be a biocompatible composite material, such as a glass or carbon fiber reinforced polymer, or a ceramic, with ceramic being preferred due to its performance and strength. The ceramic is preferably an alumina or zirconia ceramic.

[0071] The shaft preferably terminates distally in an instrument cap. The shaft is preferably cylindrical. The feedline and antenna are preferably disposed within the instrument shaft. The instrument shaft generally extends from a proximal hub and terminates distally in the distal cap. The hub includes electrical connections to electrical elements of the shaft such as the feedline, and may also include coolant inlet and outlet connections as required.

[0072] The diameter of the shaft is not limited and will generally be made to suit the intended purpose, for example in the case of an ablation needle it is important to have a narrow needle which limits damage caused during insertion while allowing fine control of positioning, so that the diameter of the needle shaft is 1.4-3mm, preferably 1.5-2.5mm, especially 2-2.5mm.

[0073] The probe 307 of FIG. 3 includes an applicator cap 330. In an embodiment, the applicator cap 330 is formed of a biocompatible metal or ceramic, such as, preferably, stainless steel or ceramic. The applicator cap 330 can include a circular base and a distal tip (e.g., a trocar tip). The tip of the applicator cap 330 is disposed at a distal end of the applicator cap 330 and can include a sharp tip configured to penetrate tissue. The circular base can be configured to be sealed by a sheath of the probe 307, such that the interior of the probe 307 is fluidly insulated from the exterior of the probe 307.

[0074] The shaft may further include an echogenic region on an exterior surface configured to be visible in ultrasound imaging. In one embodiment, this region includes a coating containing acoustically reflective microspheres. The echogenic region extends to cover at least a region of the shaft radially outward of the antenna. The probe 307 of FIG. 3 includes an echogenic region 325 configured to be visible in ultrasound imaging, which in one embodiment includes a coating containing acoustically reflective microspheres.

[0075] Where the shaft contains metallic and non-metallic portions, the junction between the metallic and non-metallic portions where they abut may be a potential site of weakness, particularly where the non-metallic portion is ceramic, as ceramics are generally less flexible and more brittle than metals such as stainless steel.Thus, the shaft preferably additionally includes a resilient element between this portion and the metallic portion, which is configured to impart resiliency to the junction between the non-metallic (e.g., ceramic) and metallic portions of the probe shaft in use.

[0076] The probe 307 further includes a region 320 configured to reduce strain on the probe induced during use, for example due to bending of the shaft. This strain relief region is particularly beneficial when the distal portion of the probe sheath is ceramic. The strain relief region 320 is configured to further increase the flexibility of the probe 307 to avoid breakage of the probe 307 during medical procedures.

[0077] An elastic element may also be present between the non-metallic region and the cap, but this may be absent due to the smaller strain on the shaft at this location. The elastic element may, for example, comprise an elastic annular spacer, which may be formed of an elastic thermoplastic elastomer, such as polyether block amide (PEBA) - trade name PEBAX® or Vestimid® E (Evonik Industries), or a polyacryletherketone (PAEK), such as polyetheretherketone (PEEK). The spacer is preferably formed in a shape and configuration to space the proximal end of the non-metallic portion from the distal end of the metallic portion. The elastic element preferably abuts the metallic portion at a proximal surface and abuts the non-metallic portion at a distal surface. The elastic annular spacer generally extends radially outward to form a surface flush with the outer surface of the probe shaft. The radially inner portion of the annular spacer may extend proximally and / or distally to provide an annular step configured to support the inner surface of the proximal end of the non-metallic portion and / or the distal end of the metallic portion. In one preferred embodiment, the annular spacer extends proximally to form an annular step configured to support the inner surface of the distal end of the metallic portion, but does not extend distally. The instrument shaft may also include an adapter sleeve for supporting the junction between the non-metallic and metallic portions of the shaft. The adapter may be configured to account for thickness differences, if any, between the non-metallic and metallic portions of the shaft, for example to form a smooth surface transition between the metallic and non-metallic portions. This may be metallic or non-metallic, such as a thermoplastic elastomer, e.g., PEBA PEBAX® or Vestimid® E, or a PAEK such as PEEK. The adapter is particularly important when the non-metallic portion is ceramic, due to the thickness required to increase the strength of the ceramic and the risk of bending the shaft causing cracks at this site. In a preferred embodiment, the sleeve extends sufficiently on either side of the joint to provide support for the joint and is positioned generally radially inward of the shaft, generally between the feedline and the inner wall of the shaft. The adapter sleeve is preferably metallic.

[0078] Both the resilient element and the adapter sleeve include strain relief regions. The resilient element and the adapter sleeve may be unitary or separate. In one preferred embodiment, the strain relief region includes the resilient element, which comprises a resilient annular spacer shaped and configured to space the proximal end of the non-metallic portion from the distal end of the metallic portion, the spacer configured to abut the metallic portion at a proximal surface and the non-metallic portion at a distal surface, the spacer extending radially outwardly to form a flush surface with the outer surface of the probe shaft, a radially innermost portion of the spacer extending proximally to form an annular step configured to support an inner surface of the distal end surface of the metallic portion, and the strain relief region additionally includes adapter sleeves extending radially inwardly of the annular spacer on either side of the junction, preferably extending proximally of the annular spacer and configured to contact and support an inner surface of the distal end of the metallic portion of the shaft, and preferably extending distally of the spacer and configured to contact and support an inner surface of the proximal end of the ceramic portion of the shaft.

[0079] The microwave tissue ablation instrument 300 includes a housing 310. The housing 310 houses coaxial cables, fluid lines, electrical wires, and the like. Figure 4A is a perspective view of a microwave tissue ablation instrument 400 according to one embodiment of the present invention, and Figure 4B is a cross-sectional view along line XY to illustrate one embodiment of a cooling mechanism.

[0080] 4A includes a shaft 401 having a metallic portion 445 and a ceramic portion 402. Ceramic portion 402 extends from a distal end 406 of a collar 405 to a base 441 of a cap 440. Ceramic portion 402 is shown separated from shaft 401 to show the internal elements of the instrument.

[0081] Tissue ablation device 400 includes a resilient element (e.g., collar 405) and an adapter 410 for coupling metal portion 445 of the shaft to ceramic portion 402. In the device of the present invention, the adapter acts to accommodate the difference in shaft thickness between the two portions, as well as to reduce bending between metal portion 445 and ceramic portion 402. In the device of the present invention, a resilient annular spacer between the ceramic and metal portions of the shaft shown here provides resilience in this region, reducing the occurrence of breakage at this point due to distortion of the shaft during use.

[0082] 1A or 1B, microwave energy generated by the microwave generator can be supplied to the antenna by a power cable that electrically connects the microwave generator to the feedline 432 of the antenna 452 in the instrument 400. The microwave ablation instrument also includes a shaft that surrounds and is generally coaxial with at least a distal end portion of the microwave antenna and feedline. The shaft generally extends from a proximal hub to a distal cap.

[0083] The feedline preferably includes an inner conductor, an outer conductor, and a dielectric disposed therebetween. The feedline may include an additional dielectric or insulator that insulates the outer conductor from other components of the instrument and acts as an outer insulator to the feedline, although this is not necessary in all embodiments. In some embodiments, the additional dielectric may be absent in the distal portion of the feedline, at least up to the junction point. The feedline may be devoid of such additional dielectric within the instrument shaft, such as between the proximal feedline connector at the distal hub and the junction point with the antenna. The feedline is typically a coaxial cable having a central conductor surrounded by a first dielectric or insulator, which is surrounded by a second conductor, which may be coated with an additional dielectric or insulator as described above. The inner conductor is typically a power conductor.

[0084] 4A, tissue ablation instrument 400 has an antenna 452 that includes a helical arm 412 and a linear arm 420. A distal end 435 of helical arm 412 forms an electrical connection with an outer conductor 430 of a feedline 432 at a junction point 436. In some embodiments, the junction point is preferably located toward or at the most distal end of the feedline. Feedline 432 may extend beyond the junction point to provide adequate mechanical support for the electrical junction, but preferably does not extend beyond the junction point by more than 5 mm, and more preferably by less than 1 mm.

[0085] Typically, the spiral arm is in the form of a conductor. The spiral arm of the antenna may be in the form of a wire or ribbon, but is typically a wire or ribbon having a circular cross section. The spiral arm is preferably in the form of a cylindrical conductor, with a spiral gap running from the proximal to the distal end to provide a spiral conductor with a flat conductor surface that curves around the outer periphery of the feedline. The spiral arm has no other contact with either the inner conductor or the outer conductor, except at the junction.

[0086] In the example of Figure 4A, the spiral arm 412 wraps around and extends coaxially around the feedline 432 proximally from junction 436. The spiral arm 412 makes no other electrical contact with the inner conductor 427 or the outer conductor 430, except at junction 436. The spiral arm may be adhesively secured to its substrate to hold it in place and to facilitate assembly. The spiral arm may be embedded in a matrix, such as a polymer layer or coating, to protect the spiral arm, to insulate it from other parts of the device, or to form a seal.

[0087] In some embodiments, the spiral arms are not wound in direct contact with the feedline. They may be wound, for example, at a radially offset location from the feedline. The spiral arms are preferably wound around a substrate that supports them. If the feedline includes an outer insulator, the outer insulator may be the substrate for the spiral arms, and the spiral arms may be wound around the outer insulator. Alternatively, the spiral arms may be wound around a tubular substrate, for example, a cooling tube that is disposed around the feedline.

[0088] In some embodiments, the total number of turns (N) ranges from 1 to 12, but is not limited to an integer. In preferred embodiments, N is generally 4 to 8. For one complete turn of the helix, the axial distance is the pitch (P), which can range from 0.7 to 1.5 mm, preferably the pitch ranges from 1 to 1.5 mm, and in preferred embodiments, the pitch (P) of the helical arm is 1.2 to 1.25 mm. The number of helical loops (N), the pitch (P), can affect the microwave energy output, the shape of the irradiation field, and the energy absorption spectrum. By appropriately selecting each variable in combination, an ablation instrument with advantageous properties for tissue ablation can be provided.

[0089] In the example of FIG. 4A, the spiral arm is wound around a tube 426 that runs from a hub (not shown) through a metal portion 445 of the shaft to a tip 428 of the antenna 452. An electrical connection between the spiral arm 412 of the antenna and the outer conductor of the feedline 432 passes through the tube at a junction 436. In the illustrated example, the spiral arm 412 has a length (Lha). In some examples, the total length (Lha) of the spiral arm can range from 1 to 18 mm, preferably the spiral arm ranges from 4 to 10 mm. In a preferred embodiment, the spiral arm ranges from 4 to 7 mm.

[0090] Linear arm 420 is an extension of inner conductor 427 of feedline 432 and is surrounded by dielectric layer 425 except for a second portion 423 which is free of dielectric. The linear arm of the antenna described herein is electrically connected to the inner conductor of the feedline and is preferably a conductor extending distally on an axis coaxial with the helical arm and / or the feedline. The conductor is preferably in the form of a straight wire. In a particularly preferred embodiment, the linear arm includes a first proximal insulated portion and a second distal uninsulated portion. Generally, the first portion is surrounded by a dielectric and the second portion, distal to the first portion, is devoid of dielectric. The second portion extends to the tip of the arm. The dielectric surrounding the first portion of the linear arm preferably extends from the distal end of the feedline. In its simplest form, the linear arm of the antenna may be an extension of the inner conductor of the feedline. The dielectric may thus be an extension of a dielectric disposed between the central and outer conductors of the coaxial feedline.

[0091] Preferably, the linear arm and the helical arm of the antenna are coaxial with the shaft of the ablation instrument, so that the linear arm is coaxial with and extends distally from the helical arm. As shown, the linear arm 420 of the asymmetric dipole antenna of FIG. 4A has a length L1a. The linear arm includes a first portion L1 421 that is covered with insulation and is an extension of a first dielectric layer, not visible in this view, of the feedline 432, disposed between the inner conductor 427 and the outer conductor 430. The linear arm 420 further includes a second portion 423, which has a length L2 422 and is not covered with insulation. In one embodiment, the second portion L2 422 is exposed to a circulating coolant.

[0092] In one embodiment, the dielectric-free portion of the linear arm is partially or completely inserted into the metal cap, but does not contact the cap. This is accomplished by forming an open pocket at the base of the cap into which this portion or part of the antenna is inserted. How far the exposed distal tip is inserted affects the shape of the distal portion of the energy field and therefore the shape of the ablation region.

[0093] If the distance between the tip and cap is greater than 3 mm, they are not believed to be sufficiently coupled to be beneficial in shaping ablation, especially at 2.45 GHz. The length (Lla) of the linear arm 420 is preferably 4 mm to 14 mm, preferably 8 mm to 10 mm. The length (L2) of the second exposed portion 423 is preferably 0.1 mm to 2 mm, preferably 0.3 mm to 0.5 mm.

[0094] Thus, in a preferred embodiment, the antenna helical arm 412 is in the form of a ribbon having a length (Lha) of 1-18 mm and containing 1-14 turns, and the antenna linear arm 420 is 4-14 mm long and has a dielectric-free second distal portion 423 having a length of 0.1-3 mm, the dielectric-free portion being spaced 0.2-3 mm from the base of the cap.

[0095] In a more preferred embodiment, the helix 412 arm of the antenna is in the form of a ribbon having a length (Lha) of 4-10 mm and containing 4-8 turns, and the linear arm 420 of the antenna is 7-10 mm long and has a second distal portion 423 lacking dielectric having a length of 0.3-0.5 mm, the portion lacking dielectric being spaced 1-2 mm from the base of the cap.

[0096] In a more preferred embodiment, the antenna helical arm 412 is in the form of a ribbon having a length (Lha) of 4-6 mm and containing 3-5 turns, the linear arm 420 having a length of 7-10 mm and a dielectric-free second distal portion 423 having a length of 0.3-0.5 mm, the dielectric-free portion being spaced from the base of the cap by 1-2 mm, preferably 1.5 mm or about 1.5 mm.

[0097] If the shaft has a non-metallic portion (e.g., ceramic portion 402), the non-metallic portion preferably extends axially to cover the antenna and therefore is at least coextensive with the radiating portion of the antenna. In one embodiment, the non-metallic portion extends at least from the proximal-most point of the helical arm to the distal end of the shaft (e.g., the attachment point of the tip of the instrument). The non-metallic portion extends axially and circumferentially, such that the shaft is preferably non-metallic between the proximal and distal extents of the non-metallic portion.

[0098] The cap may be configured to seal the distal end of the instrument to prevent leakage of coolant or penetration of tissue fluids. The cap may be manufactured as a separate piece and configured to be attached to the shaft. The cap is preferably configured to aid in insertion into tissue and pierce the patient's skin, for example to a distal point, or may be configured as a trocar. The cap 440 shown in FIG. 4A includes a trocar tip. The trocar tip of the cap 440 may be made of stainless steel and / or ceramic.

[0099] In some examples, the cap may be formed of any suitable biocompatible material, for example a biocompatible polymer, composite, ceramic, or metal such as stainless steel. If the cap is metal, the cap and the distal end of the antenna (i.e., the distal end of the linear arm of the antenna) may be configured to be electromagnetically coupled. This can be done by adjusting the distance between the distal tip of the antenna and the cap so that they are electromagnetically coupled at the frequency and power at which the antenna is intended to operate. This effect can be used to adjust the shape of the distal portion of the energy field generated by the antenna, and therefore the shape of the ablation region. However, the cap and the antenna may not be so coupled, i.e., the antenna may be electromagnetically separated from the cap. It is preferred that the tip and the cap do not contact. In practice, the gap between the tip and the cap is 0.2 mm or more, particularly 0.2 mm to 3 mm, and most preferably 1 to 2 mm. Most preferably, it is 1.5 mm or about 1.5 mm.

[0100] The shape of the energy field, and therefore the ablation volume, is also influenced by providing a metal sheath concentric with the feedline. The sheath is preferably cylindrical and extends over at least a portion of the feedline proximal to the antenna. The sheath may also extend over at least a portion of the antenna, but preferably terminates at a point proximal to the most distal end of the helical arm of the antenna and does not extend over the antenna. Preferably, the gap between the sheath and the most distal portion of the helical arm is at least 0.1 mm. The gap may be, for example, 0.1-2 mm or 0.1-1 mm, preferably 0.5 mm or about 0.5 mm. The sheath is preferably not located on the outer surface of the shaft, but is preferably radially offset from and coaxial with the feedline. Preferably, the sheath is located between the feedline and the inner wall of the shaft. In one configuration, the metal sheath may be an adapter sleeve, as described elsewhere herein.

[0101] Preferably, the coolant chamber is defined between the inner walls of the instrument shaft. The chamber may have a distal boundary defined by a cap and a proximal boundary defined by one or more proximal seals that proximally close the coolant chamber. The one or more seals are preferably formed at the hub or at a point between the hub and a proximal portion of the helical arm of the antenna. The cooling system includes at least one coolant inlet conduit configured to deliver coolant to the coolant chamber and at least one coolant outlet conduit for removing coolant from the chamber. The coolant inlet conduit and the coolant outlet conduit generally pass through the proximal seal. In one version, the coolant inlet conduit is a coolant inlet tube configured to deliver coolant to a location proximal to and radially outward of the antenna and / or feedline. In this case, the coolant inlet tube is preferably disposed within the coolant chamber between the antenna and the inner wall of the shaft. Preferably, it is radially outwardly offset from the feedline.

[0102] In an alternative configuration, the cooling system includes a coolant inlet conduit and a coolant outlet conduit, each conduit being arranged around at least a portion of the feedline and a portion of the antenna. Each conduit is arranged in the form of a helix, and the coolant inlet conduit and the coolant outlet conduit are interdigitated with each other to form a double helix. In one preferred configuration, the cooling system includes the feedline and a pair of helical partitions arranged as a double helix around at least a portion of the antenna, each partition extending radially outwardly toward the inner wall of the shaft and radially inwardly toward the antenna and / or the feedline, whereby the coolant inlet conduit and the coolant outlet conduit are formed between the two partitions, and the coolant inlet conduit and the coolant outlet conduit form a double helix. The partitions may be in the form of filaments or ribbons, or a combination of both. If the partitions include ribbons, the ribbons are preferably generally perpendicular to the inner shaft wall. The filaments may be formed of metal or elastic polymer. The partitions preferably extend sealingly against the inner wall and at least a portion of the antenna and / or the feedline.

[0103] The cooling system additionally includes a coolant mixing chamber in communication with both the coolant inlet conduit and the coolant outlet conduit, whereby the coolant inlet and the coolant outlet are in communication via the coolant mixing chamber. The coolant mixing chamber is preferably configured to allow coolant to pass through at least a portion of the antenna, particularly at least a portion of the linear arm of the antenna. The coolant mixing chamber is particularly configured to allow coolant to pass through a distal portion of the linear arm of the antenna and at least a portion of the cap.

[0104] Alternatively, and preferably, the cooling system includes a coolant chamber defined between the interior walls of the instrument shaft. The chamber may be defined at a distal boundary by the cap and at a proximal boundary by a seal between the hub and the shaft, or at a point distal to the hub and between the antenna and the hub as described above. The coolant chamber surrounds the antenna and at least a distal portion of the feedline.

[0105] In an embodiment, the cooling system includes a cooling tube disposed around the feedline, the cooling tube preferably extending distally around the feedline, preferably coaxially therewith. The cooling tube preferably divides the coolant chamber into a first cooling conduit 448 and a second cooling conduit 460, the first cooling conduit being disposed between the feedline and an inner wall of the cooling tube, and the second cooling conduit being disposed between an outer wall of the cooling tube and an inner wall of the instrument shaft. The cooling tube preferably extends to a distal portion of the feedline and extends distally around at least a portion of the antenna, preferably the cooling tube extends at least to the tip of the linear arm of the antenna. Various materials are suitable for the cooling tube, which is preferably non-metallic. In a preferred embodiment, the cooling tube may be made of a thermosetting polymer, such as polyimide, or a thermoplastic polymer resin, such as polyethylene terephthalate (PET), or a fluoropolymer, such as polytetrafluoroethylene (PTFE), or a PAEK, such as PEEK.

[0106] 4A, the spiral arms are wrapped around the tube 426, as described elsewhere herein. In one embodiment, the tube 426 defines a first cooling conduit 448 between an inner wall 454 of the tube 426 and the feed line 432, and a second cooling conduit 460 between an outer wall 455 of the tube 426 and an inner wall of the shaft 453. Coolant may be delivered through the space between the tube 426 and the feed line 432, into a mixing chamber 429 between the tube 426 and the cap 440, back through the space between the outside of the tube 426 and the ceramic portion 402 of the shaft, through the space 411 between the inside of the shaft and the adapter 410, through the metal portion 445 of the shaft, and back to the hub.

[0107] The helical arm of the antenna may be disposed within the first cooling conduit, e.g., the distal portion of the feedline may include a second insulator as described above, with the helical arm of the antenna wrapped directly around the feedline and the second insulator extending axially at least between the helical arm and the second conduit of the feedline, in which case the cooling tube extends over a portion of the helical arm, preferably over the helical arm and at least a portion of the linear arm, but most preferably the cooling tube extends at least to the distal end of the antenna, whereby the first cooling conduit extends at least to the tip of the antenna.

[0108] Instead, the cooling tube extends over the tip portion of the feedline and a portion of the linear arm, but most preferably the cooling tube extends at least to the distal end of the antenna, whereby the first cooling conduit extends at least to the tip of the antenna.

[0109] The cooling system may additionally include a coolant mixing chamber in communication with both the first cooling conduit and the second cooling conduit, whereby the first cooling conduit and the second cooling conduit are in communication through the coolant mixing chamber. The coolant mixing chamber is preferably configured to allow coolant to contact a portion of the cap.

[0110] Either the first or second cooling conduits can function as a coolant inlet conduit or a coolant outlet conduit. The first and second cooling conduits are open at their distal ends so that coolant can circulate through a coolant mixing chamber between the distal end of the cooling conduit and the base of the applicator cap.

[0111] The cooling tube preferably extends proximally towards the hub, and the first and second cooling conduits communicate with coolant inlet and outlet connectors on the hub for coolant supply and coolant exhaust during use.

[0112] In a particularly preferred manner, the helical arm of the antenna is wrapped around the cooling tube, preferably in the form of a ribbon. In this case, the helical arm is in electrical contact with the outer conductor of the feedline at the junction and extends distally as a series of turns around the cooling tube as described above. In this case, the cooling tube preferably extends at least to the junction of the antenna and the feedline, preferably it extends over at least a portion of the linear arm, but most preferably the cooling tube extends to the tip of the linear arm, whereby the first cooling conduit extends at least to the tip of the antenna. Preferably, the electrical contact between the distal end of the helical arm and the outer conduit of the feedline passes through the cooling tube.

[0113] In this manner, it is preferred that the outer insulation does not extend onto the distal portion of the feedline, preferably at least the portion of the feedline that extends from a point just proximal to the helical arms of the antenna to the junction point, and the outer insulation may be absent anywhere on the feedline within the shaft of the ablation instrument.

[0114] In embodiments where the cooling system includes a cooling tube as described above, the helical arms can be either wires or ribbons, but are most preferably ribbons. The helical arms are preferably in the form of a cylindrical conductor with a helical gap extending from its proximal end to its distal end, resulting in a helical conductor having a flat conductor surface disposed about, and preferably coaxial with, the feedline.

[0115] The cooling systems described herein pass a coolant (e.g., water) through the feedline and at least a portion of the antenna, preferably throughout the entire antenna. It is not necessary to isolate the antenna from the coolant for normal operation. In some embodiments described herein, a portion of the feedline does not have outer insulation surrounding the feedline. The feedline may be free of insulation between the hub and the junction, or along its entire length within the instrument shaft. The spiral arm of the antenna may be devoid of insulation, especially if it is wrapped around a cooling tube.

[0116] The ablation instruments described herein may additionally include one or more temperature sensors, e.g., thermocouples, for measuring the temperature at points along the shaft. Typically, the thermocouples are located within the cooling system and may be configured to measure the temperature of the coolant or other components of the instrument, such as the feed lines or instrument shaft, during operation of the instrument. The tissue ablation instrument 400 of FIG. 4A includes a temperature sensor 450 stored next to the internal adapter 410 and having an electrical connection 451 to the control unit via the hub.

[0117] As described elsewhere herein, ablation instruments such as those described herein generally include a proximal hub, as already briefly mentioned. The hub generally includes connectors for connecting the feed lines to the energy supply lines and for connecting the electrical equipment in the instrument shaft to a control system. Such connectors may be permanent or removable. The hub may also include a coolant manifold with input and output connectors for connecting the coolant intake to a coolant supply and the coolant exhaust to a waste or recirculation system. The hub may also form part of a handle configured to provide a more secure grip for the surgeon to manipulate the tissue ablation instrument.

[0118] 5 is a side view of a microwave tissue ablation instrument according to one embodiment of the present disclosure. The ablation instrument 500 includes a handle 501. The handle 501 houses a manifold 505.

[0119] Manifold 505 electrically connects a power source (not shown) to tissue ablation probe 530 through coaxial cable connector 515. Tissue ablation probe 530 includes indicia 535 configured to inform the surgeon of the penetration depth of the probe during surgery.

[0120] Manifold 505 also communicates with a coolant source (not shown) and tissue ablation probe 530. Manifold 505 includes a coolant inlet 520 and a coolant outlet 525. Coolant inlet 520 is communicated with a coolant inflow conduit and coolant outlet 525 is communicated with a coolant outflow conduit.

[0121] Tissue ablation instrument 500 further includes a tubular housing 540 that houses the electrical wires and fluid conduits. As described elsewhere herein, multiple ablation instruments, such as tissue ablation instrument 300, may be used simultaneously to perform the ablation process. Such ablation instruments may be arranged in a variety of ways. FIG. 6A shows plan views of various configurations of microwave ablation needles. In one example, the microwave ablation instruments may be arranged equidistant from one another, such as in arrangement 600. The needles may be arranged in a regular polygonal arrangement, such as in arrangements 600, 610, and 620. Arranging the ablation instruments equidistant from one another may preferably form a net ablation volume formed by the multiple ablation instruments that is approximately symmetrical. Additionally, arranging the ablation instruments in a regular polygonal arrangement may form a net ablation volume formed by the multiple ablation instruments that is approximately spherical. Alternatively, the multiple instruments may be arranged in other arrangements, such as linearly, such as in arrangement 630, or irregularly, such as in arrangement 640. The ablation instruments may be arranged in a variety of configurations to form a desired ablation volume suited to a particular procedure.

[0122] Additionally, such instruments can be inserted to the same or different penetration depths. FIG. 6B shows a front view of multiple ablation instruments in different depth configurations. An ablation instrument, such as microwave tissue ablation instrument 300, can be inserted to a particular depth, as measured by, for example, markers 311. In some configurations, the instruments are inserted to approximately the same depth, such as in configuration 605. In other examples, the instruments can be inserted to different depths, such as in configurations 615, 625, and 635. As with the different planned configurations, the ablation instruments can be positioned in a variety of configurations to create a desired ablation volume suited to a particular procedure.

[0123] During a procedure involving one or more ablation instruments, a pump (e.g., 148a) can be activated at the console (e.g., 102) to cause coolant to flow from a coolant source (e.g., 140) to each of the one or more ablation instruments (e.g., 400). For each ablation instrument, coolant can flow through a coolant line (e.g., 114a), a coolant inlet (e.g., 520), a first cooling conduit (e.g., 448), a second cooling conduit (e.g., 460), and a coolant outlet (e.g., 525). In some instances, the coolant line (e.g., 114a) forms a return path that receives fluid from the coolant outlet (e.g., 525), for example in a recirculation system where coolant is recirculated back to the coolant source. In certain embodiments, coolant can flow through such flow paths to cool the ablation instruments.

[0124] As described herein, for example, a controller (e.g., 106) in a console (e.g., 102) that receives the ablation instrument (e.g., 400) can be used to control the flow of fluid through the ablation instrument, as well as the microwave energy emitted from the ablation instrument.

[0125] The coolant can also act as a dielectric to couple microwave radiation emitted from the microwave antenna (e.g., 452) to surrounding tissue when the microwave ablation instrument is inserted into the patient's body. In some embodiments, the coolant flows through the needle at a therapeutic ablation flow rate during the therapeutic ablation process. The coolant flowing through the needle at a therapeutic ablation flow rate can couple microwave energy emitted from the needle to the tissue surrounding the needle and affect the penetration depth of the microwave energy into the tissue. Reducing the flow of the coolant can reduce the coupling of microwave energy to the surrounding tissue, resulting in a smaller ablation region. Additionally or alternatively, reducing the flow of the coolant can reduce the ability of the needle to remove heat from the tissue near the needle, resulting in more localized heating of the tissue near the needle compared to a higher flow rate.

[0126] In some embodiments, a pre-ablation procedure is performed to ensure that the ablation system is operating properly. An exemplary pre-ablation procedure is shown with respect to FIG. 7. The ablation device may first be tested in a medium other than the patient's tissue, such as saline, sterile water, or other sterile medium, such as a solid or semi-solid material that mimics the dielectric properties of tissue, commonly referred to as a tissue simulator or tissue phantom (step 710). It is also contemplated that the pre-ablation procedure may be performed in the patient's tissue using a power level that is lower than the power levels typically delivered to the patient's tissue during an ablation procedure, such as the power levels described below.

[0127] Once the ablation device is placed in the appropriate medium or tissue, a pre-ablation procedure may be initiated, such as the pre-ablation procedure shown in FIG. 7 at step 720. The pre-ablation procedure may be initiated manually by a user (e.g., a physician) or automatically by the system, such as after contact with the appropriate medium or tissue or a specific time after power-on. In embodiments in which a coolant is used, the pre-ablation procedure may be initiated by starting a pump (e.g., pumps 148a-c) to supply coolant to the ablation device (step 730). The pre-ablation procedure 720 may additionally include delivering energy to the appropriate medium (e.g., sterile water) or tissue. In a preferred embodiment, the power delivered to the appropriate medium or tissue is generally lower than the power delivered to the patient's tissue, e.g., at a power level of 1-20 W, although power levels below 1 W and above 20 W are also contemplated. Preferably, a power level of 5 W is used for the pre-ablation procedure. The power levels used for pre-ablation treatments may depend in part on the measurement system used, as lower power levels may be used with more sensitive measurement systems.

[0128] The ablation power level can be controlled in at least two ways: by controlling the amplitude or by utilizing duty cycling. For example, if it is desired to apply an average power level of 40 W, this can be achieved by either setting the power level at 40 W, or by setting the power level at a higher value of 80 W and using a 50% duty cycle. Both methods of controlling the power level are contemplated.

[0129] During the pre-ablation procedure 720, power may be delivered to the ablation device for a predetermined duration, e.g., 5-30 seconds, although other durations, e.g., less than 5 seconds or more than 30 seconds, are contemplated. Preferably, the pre-ablation procedure has a duration of 10 seconds. The duration may be specified by the ablation system, e.g., by a default predetermined duration. In some embodiments, a user may select the predetermined duration, e.g., by selecting from a list or by entering a specified duration. The duration may also be based on a user selecting a power level delivered to the ablation device, e.g., by manipulation (e.g., a button, switch, touch interface). The duration may additionally depend on the total amount of power (e.g., energy) delivered to the ablation device.

[0130] The pre-ablation procedure can be used to determine if the ablation system is functioning properly before it is used in an ablation procedure. It is advantageous for a user or physician to determine if there are any issues with the console, ablation tool, or system setup before using the ablation system on a patient (e.g., via an ablation procedure) to ensure that the ablation procedure is performed properly. An improper ablation procedure can result in an incomplete ablation or discomfort or harm to the patient.

[0131] The pre-ablation procedure 720 may additionally include monitoring data, such as temperature data and / or power data (step 750), to determine whether the ablation system is functioning properly. The temperature data may represent the temperature of the ablation instrument or the temperature of the medium or tissue surrounding the ablation instrument. In embodiments where a coolant is used, the temperature data may also represent the temperature of the coolant within the ablation instrument. With respect to the temperature data, it may be desirable to keep the ablation instrument or coolant within a temperature range, such as above 15F and below 25F. Additionally, temperature changes may be used to determine the functioning of the ablation system, for example, a sudden change in temperature may be indicative of the presence of air bubbles in the coolant. A sudden rise in the temperature of the coolant after power is initially delivered to the ablation instrument may also indicate that the system is not functioning properly.

[0132] With respect to the power data, the power data may be used to calculate the power efficiency, e.g., the ratio of reflected power to delivered power. As also indicated above, it may be desirable to have the efficiency within a threshold range, e.g., within the range of 60% to 80%. Preferably, the power efficiency is greater than 75%. Additionally, deviations in efficiency may be used to identify the functionality of the ablation system. For example, a dramatic change in efficiency may indicate a loose connection in the system or an air bubble in the coolant, if used. Additionally or alternatively, the delivered power and the reflected power may be used to identify the functionality of the ablation system, e.g., using thresholds and deviations as described herein. Changes in efficiency may also indicate the presence of inadequate coolant, the absence of coolant, the ablation device not functioning properly, the pre-ablation procedure set-up is incorrect, or the ablation device is not positioned properly within the medium or tissue.

[0133] After power has been delivered to the ablation instrument for the desired duration and / or after the desired amount of power has been delivered, the power delivered to the ablation instrument is stopped (step 760). Additionally, in embodiments using a coolant system, step 760 may include stopping a pump (e.g., pump 148) such that no more coolant is delivered to the ablation instrument. Alternatively, the pump may continue to deliver coolant into the ablation instrument after the pre-ablation procedure such that coolant is delivered continuously between the pre-ablation procedure and the ablation procedure.

[0134] Information regarding the status of the ablation instrument may be provided after terminating the power supplied to the ablation instrument (step 770). In some embodiments, information regarding the status of the ablation instrument may be provided throughout the pre-ablation procedure. Information regarding the status of the ablation instrument may include temperature and / or power data collected during the pre-ablation procedure. The information may be provided to the user via a user interface (e.g., the graphic user interface 900) and / or stored in memory for later use. Additionally or alternatively, the information may include a notification informing the user as to whether the ablation instrument is functioning properly or not. The notification may be displayed on a display and may be an LED (e.g., green if functioning properly and red if not functioning properly) or any other notification system known in the art.

[0135] The pre-ablation procedure may be performed at any time, such as during a routine maintenance check, upon manipulation of an element of the ablation system, upon command input by a user, or upon powering up of the ablation system, etc. In a preferred embodiment, the pre-ablation procedure is performed prior to performing an ablation procedure, such as ablation procedure 800 described with respect to FIG.

[0136] With respect to ablation procedure 800, the ablation system may first identify ablation procedure parameters (step 810), for example, by receiving input regarding ablation parameters. The ablation procedure parameters may be the size of the target area, the positioning of one or more ablation instruments, including the geometry of the instruments within the tissue if multiple instruments are used, a predetermined ablation instrument duration, and / or a predetermined amount of energy. The ablation system may receive input regarding the ablation procedure parameters via a user interface, such as by adjustable parameters 940 of a graphic user interface (GUI) 900. With respect to adjustable parameters 940, the ablation system may receive input regarding the diameter of the target area (e.g., 3.5 cm) and the placement of the ablation instruments (e.g., the placement shown in FIGS. 6A and 6B). The ablation system may also provide proposed ablation parameters in response to receiving input regarding the target tissue area or dimensions. These parameters may include a recommended ablation power level, total energy, and / or ablation duration for the ablation procedure.

[0137] After identifying the ablation procedure parameters, the ablation system may begin delivering ablative power to the target region (step 820). Step 820 may be performed automatically, such as after identifying the ablation procedure parameters in step 810, or may be performed manually, such as by the ablation system receiving input from a user. In embodiments in which a coolant system is used, the ablation procedure may additionally initiate one or more pumps, such as pumps 148a-148c, to supply coolant to the ablation device.

[0138] Similar to pre-ablation procedure 700 and other ablation procedures described herein, the ablation system can monitor the ablation power within the ablation system, as shown in step 830. Monitoring the ablation power can include monitoring the delivered power and / or the reflected power.

[0139] Additionally or alternatively, the duration may be determined based on whether an energy target has been achieved (e.g., a predetermined amount of energy). As shown in step 840, the ablation instrument may continue to deliver ablation energy until the energy target is achieved. Determining whether the energy target has been achieved may include monitoring the delivered and / or reflected power of the ablation instrument. Ideally, all of the power delivered to the ablation instrument is delivered to the target area. However, based on power level parameters (e.g., amplitude, frequency, etc.), the composition of the target area (e.g., tissue type, water content, etc.), the type of ablation instrument used, or the proximity of other media (e.g., bone, air pockets, other ablation instruments, auxiliary instruments, etc.), a portion of the power delivered to the ablation instrument may be reflected. Additionally or alternatively, poor coupling between the ablation instrument and surrounding tissue may cause power reflection within the ablation instrument.

[0140] The ablation system may be able to determine the delivered and / or received power of the ablation instrument, for example, by receiving information regarding the delivered and / or reflected or coupled power. In some embodiments, the ablation instrument may include a directional coupler. The directional coupler may be used to measure the delivered and received power on the ablation instrument. Additionally or alternatively, other devices may be used to determine the received power, such as a directional coupler on an additional ablation instrument or an antenna configured to receive power. When using a directional coupler or similar device, the reflected power may be determined by monitoring the received power (e.g., the S of the directional coupler). 11 In such an embodiment, S 11 The signal may represent the power reflected by the ablation needle and not received by the tissue. Additionally, monitoring the reflected or coupled power may be used to determine the delivered power. In some embodiments, all power not reflected or coupled is assumed to be delivered power.

[0141] In addition to monitoring the delivered and received power, step 830 may additionally include measuring temperature during the ablation procedure. As described herein, the ablation system may include one or more temperature sensors, such as temperature sensor 450. The temperature monitored by the one or more temperature sensors may be representative of the ablation device or tissue surrounding the ablation device. Additionally or alternatively, the temperature monitored by the one or more temperature sensors may be representative of the temperature of the coolant in some embodiments.

[0142] After the desired amount of energy has been applied (e.g., the energy target has been reached in step 840) or power has been delivered to the ablation instrument for the desired duration, the power delivered to the ablation instrument is stopped (step 860). Additionally, if coolant is being used, the pump (e.g., pump 148) may be stopped so that no more coolant is supplied to the ablation instrument. Alternatively, coolant may be supplied after the ablation procedure, such as if another ablation procedure is to be performed shortly thereafter.

[0143] The ablation system may monitor the temperature of the tissue after power is no longer supplied to the ablation instrument, as shown in step 870. The temperature of the tissue may be monitored by a sensor located within the ablation instrument, or by an external temperature measuring device, such as a temperature sensor (e.g., temperature sensor 450), or by monitoring the temperature of the coolant, which reflects the tissue temperature. The post-ablation temperature may indicate how well the tissue surrounding the ablation instrument was ablated. For example, if not enough ablation power was supplied, the post-ablation temperature may indicate that the temperature of the surrounding tissue did not rise to an acceptable temperature to fully ablate the target area. For example, the tissue temperature should generally be raised to a temperature above 50°C, preferably above 60°C.

[0144] The monitored values ​​throughout the ablation procedure may be used to calculate an ablation score (step 880). As shown in FIG. 8, both the monitored power and temperature values ​​may be used to calculate an ablation score. The ablation score may represent the quality of the ablation at the end of the ablation procedure. The ablation score may additionally be influenced by other values, such as information stored during the pre-ablation procedure. In some examples, the monitored values ​​throughout the ablation procedure are weighted unevenly in calculating the ablation score. For example, the ablation score may be calculated using the monitored power, such as the power efficiency during the ablation procedure. Additionally or alternatively, the ablation score may be influenced based on whether a threshold value has been reached. For example, if the ablation procedure has not reached the required post-ablation temperature, a low ablation score may be assigned regardless of the performance of other monitored / calculated values ​​(e.g., power efficiency).

[0145] The ablation score may be stored along with the monitored values, the ablation procedure parameters, the pre-ablation treatment information, the ablation system used, and / or the location of the target region (e.g., the type of tissue in the patient's body). The stored ablation score may be used to identify the effectiveness of the ablation procedure in order to perform effective or more effective ablation procedures in the future.

[0146] FIG. 9 illustrates an exemplary GUI 900 for an ablation system. In some embodiments, a numerical total efficiency value is displayed. Such a numerical efficiency value can be presented in real time during ablation and can represent the efficiency of the ablation to that point (e.g., 99% efficiency with 2.16 remaining as shown in FIG. 9). Small increments in efficiency can also be recorded and displayed, such as those shown in graph 910. During the ablation procedure, a numerical efficiency value can be calculated every second. Graph 910 displays the change in efficiency over time. In the ablation procedure shown in graph 910, the efficiency increases and decreases between 98% and 100%. In some examples, GUI 900 can include both a plot of efficiency versus time (e.g., graph 910) and a numerical total efficiency value. GUI 900 can additionally display a graphical representation of the energy delivered, such as a bar graph 920 shown below graph 910.

[0147] The ablation system may also be configured to convert the delivered power and / or power efficiency into a numerical value for delivered energy and / or energy efficiency. For example, the integral of the delivered power over time may be calculated to determine the total delivered energy. The delivered energy value may be compared to the provided energy value to determine the energy efficiency.

[0148] The GUI 900 may additionally provide a graphical representation of the ablation procedure, for example, the shape and size of a theoretical target area based on the positioning of one or more ablation instruments to be used. For the ablation procedure shown on the GUI 900, the display 930 displays three ablation instruments positioned with a 1.0 cm gap between them, which is expected to form an elongated spherical target area with dimensions of 6.5 x 6.5 x 7.0 cm. The shape of the expected target area may be calculated based on the ablation procedure parameters. Additionally, the display 930 may provide the location of the expected target area relative to one or more ablation instruments. For the ablation procedure shown in the GUI 900, the center of the target area is located 2.9 cm from the tip of the ablation instrument, and the bottom of the target area is located 0.6 cm from the tip of the ablation instrument.

[0149] The ablation system may receive input regarding ablation parameters, such as the size of the target area, the positioning of one or more ablation instruments, a predetermined ablation duration, and / or a predetermined amount of power / energy. The ablation system may receive input regarding the ablation procedure parameters, for example, via a user interface via adjustable parameters 940 of GUI 900. With respect to adjustable parameters 940, the ablation system may receive input regarding the diameter of the target area (e.g., 6.5 cm) and the placement of the ablation instrument (e.g., the placement shown in FIGS. 6A and 6B).

[0150] During an ablation procedure, the ablation system may receive inputs, such as inputs from a user interface (e.g., adjustable parameters 940). The received inputs may include inputs to adjust a current power level to provide more or less power to a target area. Additionally or alternatively, the ablation system may receive inputs to adjust the duration of the ablation procedure. For example, the user interface may receive inputs to increase the total duration of the ablation (e.g., +30 seconds as shown at 915) or to shorten or terminate the ablation procedure (e.g., 917).

[0151] Various non-limiting examples have been described. These and others are within the scope of the following claims. Moreover, while the invention is susceptible to various modifications and alternative forms, certain specific embodiments thereof are shown by way of example in the drawings. The drawings may not be to scale.

Claims

1. 1. A tissue ablation system comprising: an ablation instrument configured to apply energy to a target area; an ablation generator configured to provide power to the ablation device; a controller coupled to the ablation generator and configured to initiate a pre-ablation treatment in a medium prior to an ablation procedure, wherein during the pre-ablation treatment, the controller: causing an ablation generator to supply power to said ablation device; Monitor temperature data, monitoring power data representative of the power delivered to the ablation tool; and Identifying a condition of the ablation tool based on the monitored temperature data and the monitored power data. The tissue ablation system is configured as follows:

2. The system of claim 1 , wherein the power delivered to the ablation instrument is between 1 and 20 watts.

3. The system of claim 1 or 2, wherein the pre-ablation treatment comprises delivering the power to the ablation device for 5 to 30 seconds.

4. The system of any one of claims 1 to 3, wherein the medium is a tissue simulator.

5. The system according to any one of claims 1 to 3, wherein the medium is sterile water.

6. The system according to any one of claims 1 to 3, wherein the medium is tissue undergoing an ablation procedure.

7. The system of any one of claims 1 to 6, wherein the controller is further configured to supply a coolant to the ablation device.

8. The system of claim 7 , wherein the monitored temperature data is the temperature of the coolant.

9. The system of any one of claims 1 to 6, wherein the monitored temperature data is the temperature of the medium surrounding the ablation device.

10. The system of any one of claims 1 to 9, wherein the monitored temperature data is the temperature of the ablation device.

11. The system of any one of claims 1 to 10, wherein the controller is further configured to perform an ablation procedure.

12. The system of any one of claims 1 to 11, wherein the ablation instrument comprises a microwave ablation needle.

13. The system of any one of claims 1 to 12, further comprising a user interface configured to receive input regarding the pre-ablation procedure.

14. The system of any one of claims 1 to 13, further comprising a user interface configured to receive input related to the ablation procedure.

15. The system of any one of claims 1 to 14, further comprising a second ablation instrument configured to apply energy to the target area.

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