Magnetic resonance compatible transurethral non-invasive prostate-specific radiofrequency ablation electrode

Abstract

The application discloses a magnetic resonance compatible transurethral noninvasive prostate special radiofrequency ablation electrode, and belongs to the field of minimally invasive medical instruments. The electrode comprises a composite flexible catheter, a hollow cylinder radiofrequency ablation electrode, a cooling circulation channel, an inflatable balloon and a multi-point temperature sensor. The hollow cylinder electrode is internally provided with independent cooling liquid inflow and backflow channels, radiofrequency energy is uniformly diffused along the electrode in 360 degrees radially, and end ablation effect is eliminated. The inflatable balloon is arranged at the front end of the catheter, and after expansion in the bladder, the electrode is stably attached to the prostate tissue. The multi-point temperature sensor is distributed along the catheter axis, and forms a closed loop temperature control with an external radiofrequency generator. All components are made of non-ferromagnetic materials, and the whole is compatible with the magnetic resonance imaging environment. The electrode realizes precise and uniform ablation of the hyperplastic prostate tissue without puncture and incision, effectively protects the urethral mucosa, sphincter and surrounding key structures, and is simple to operate and quick to recover.

Description

Technical Field

[0001] This invention belongs to the field of medical device technology, specifically relating to the field of radiofrequency ablation therapy devices for the urinary system, and particularly to a magnetic resonance compatible transurethral non-invasive radiofrequency ablation electrode for the prostate. Background Technology

[0002] Benign prostatic hyperplasia (BPH) is one of the most common lower urinary tract obstructive diseases in elderly men. With the increasing aging of the global population, the prevalence rate exceeds 50% in men over 60 years of age and reaches as high as 83% in those over 80 years of age. Bladder outlet obstruction caused by BPH can lead to difficulty urinating, urinary retention, recurrent urinary tract infections, and even kidney damage, significantly reducing patients' quality of life and increasing the social healthcare burden. Furthermore, optimized treatment of prostate carcinoma in situ and locally invasive prostate cancer also constitutes an unmet clinical need.

[0003] Radiofrequency ablation (RFA) technology uses high-frequency alternating current to generate impedance heat within tissue, causing coagulation necrosis of the target tissue, followed by absorption and shrinkage. It has been successfully applied in the treatment of solid tumors such as those in the liver, kidneys, and thyroid. In recent years, scholars both domestically and internationally have attempted to use RFA for the treatment of benign prostatic hyperplasia (BPH) and prostate cancer, but several common challenges remain: the ablation process easily damages the urethral mucosa and surrounding vascular nerve bundles, sphincter muscles, and anterior rectal wall; the ablation depth and extent lack controllability; and there is a lack of MRI-compatible instruments specifically designed for transurethral prostate ablation.

[0004] A search revealed several existing prostate radiofrequency ablation devices. For example, Chinese invention patent CN120938582A discloses a multifunctional radiofrequency ablation catheter and synergistic device for non-invasive transurethral treatment of benign prostatic hyperplasia, integrating radiofrequency ablation, circulating cooling, catheter flushing, balloon fixation, and temperature sensing. However, this device lacks magnetic resonance compatibility design; the materials of its catheter, electrodes, and wires are not limited to non-ferromagnetic materials, making real-time positioning, temperature measurement, and ablation assessment impossible under magnetic resonance imaging. Furthermore, its temperature sensors are only located on the walls of the inlet and outlet fluid channels, not distributed at multiple points along the catheter axis, making it difficult to comprehensively monitor the temperature gradient around the electrodes and the urethral wall. In addition, the device lacks a clearly defined structural design to eliminate the end ablation effect, leaving a risk of localized overheating.

[0005] Chinese invention patent CN115120335A and utility model CN218684663U disclose a device for ultrasound-guided radiofrequency ablation of the prostate. This device uses a catheter inserted through the urethra, with multiple retractable needle-shaped ablation electrodes arranged circumferentially around the catheter. Ablation is performed by puncturing the prostate tissue. While this type of device allows adjustment of the ablation direction and range, the needle-shaped electrodes require puncture of the urethral mucosa and prostate tissue, posing risks such as urethral injury, bleeding, and rectal perforation, making it an invasive procedure. Furthermore, the cooling channel is located on one side of the electrode needle guide channel and is not integrated into the electrode itself, resulting in limited cooling efficiency. Additionally, the device lacks a balloon fixation structure, making the electrodes prone to displacement during the procedure due to changes in body position or tissue peristalsis. Moreover, it does not consider magnetic resonance imaging (MRI) compatibility.

[0006] Chinese invention patent CN121867930A discloses a tubular water-cooled radiofrequency ablation electrode, which uses a circular tubular electrode to achieve annular ablation and integrates circulating water cooling and a thermocouple for temperature measurement. However, this device is designed for transbladder access, requiring laparoscopic or cystotomy, which is an invasive surgical procedure with significant trauma; its tip does not have an inflatable balloon, and electrode fixation relies on passive positioning under surgical instruments or laparoscopic vision, lacking an active anchoring structure; furthermore, the device does not explicitly use non-ferromagnetic materials, lacking magnetic resonance compatibility; and its temperature measurement point is only a single location, unable to achieve multi-point real-time feedback.

[0007] In summary, current technologies do not offer a dedicated prostate radiofrequency ablation electrode that simultaneously possesses magnetic resonance compatibility, non-invasive transurethral insertion, radially uniform ablation with a hollow cylindrical electrode, integrated internal circulating cooling and multi-point temperature sensing, and active balloon fixation. Existing devices either lack magnetic resonance compatibility, thus failing to achieve precise intraoperative imaging and temperature measurement; or damage the urethral mucosa due to needle-like puncture; or cause significant trauma due to transbladder access; or result in uncontrollable thermal damage due to insufficient integrated cooling and temperature measurement. Therefore, there is an urgent need to develop a non-invasive, magnetic resonance-compatible dedicated prostate radiofrequency ablation electrode that can solve the above problems. Summary of the Invention

[0008] Technical Problem Solved: To address the shortcomings of existing transurethral radiofrequency ablation devices for the prostate, such as lack of magnetic resonance compatibility, inability to achieve real-time precise positioning and temperature measurement during the procedure, damage to the urethral mucosa and surrounding tissues caused by needle electrode puncture, uncontrollable thermal damage due to insufficient integration of cooling and temperature measurement, and easy displacement due to lack of active fixation structure, this invention provides a magnetic resonance-compatible, non-invasive transurethral radiofrequency ablation electrode specifically for the prostate. This electrode adopts a hollow cylindrical structure to achieve uniform energy emission in a radial direction of 360°, avoiding the end ablation effect and puncture damage of traditional needle electrodes. All components are made of non-ferromagnetic materials, enabling real-time positioning, temperature measurement, and ablation assessment under magnetic resonance imaging. The electrode integrates an independent cooling fluid circulation channel, which, together with multiple temperature sensors distributed along the catheter axis, forms a closed-loop temperature control system, effectively protecting the urethral mucosa, sphincter, neurovascular bundle, and anterior rectal wall from thermal damage. An inflatable balloon is placed at the front end of the catheter, which expands in the bladder to ensure stable adhesion between the electrode and the prostate tissue, preventing intraoperative displacement. This device can achieve precise, uniform, and controllable ablation of hyperplastic prostate tissue without cutting or puncturing, while also being compatible with magnetic resonance guidance, improving treatment safety and ease of operation.

[0009] Technical Solution: A magnetic resonance-compatible transurethral non-invasive radiofrequency ablation electrode for the prostate includes a composite flexible catheter, a hollow cylindrical radiofrequency ablation electrode, a cooling circulation channel, an expandable balloon, and multi-point temperature sensors disposed on the composite flexible catheter. The hollow cylindrical radiofrequency ablation electrode has independent coolant inflow and return channels, forming a cooling circulation channel. The expandable balloon is disposed at the front end of the composite flexible catheter for expansion within the bladder to align and adhere the electrode to the prostate tissue. The multi-point temperature sensors are distributed along the axial direction of the composite flexible catheter for real-time monitoring of the temperature of the electrode, urethral wall, and cooling water. The wires of the composite flexible catheter, the hollow cylindrical radiofrequency ablation electrode, the expandable balloon, and the multi-point temperature sensors are all made of non-ferromagnetic materials.

[0010] The aforementioned composite flexible catheter is made of medical-grade polymer material, and its distal end is a smooth, blunt, blind end.

[0011] The hollow cylindrical radiofrequency ablation electrode has a length of 20-50 mm and an outer diameter of 4-8 mm. It adopts a circular tube structure, and the radiofrequency energy diffuses uniformly outward along the radial direction of the electrode, thus avoiding end ablation of the electrode.

[0012] The aforementioned cooling circulation channel includes an inlet channel and an outlet channel disposed within a composite flexible conduit, as well as an inlet pipe and an outlet pipe respectively connected to the inlet channel and the outlet channel; the coolant inflow channel and the return channel are connected inside the electrode to form a circulation loop, and the coolant flow is driven by an external coolant circulation system.

[0013] The aforementioned inflatable balloon is made of elastic medical polymer material and is a gas or liquid-filled balloon. The composite flexible catheter contains a balloon tube, the distal end of which is connected to the inflatable balloon, and the proximal end of which is connected to the inflation / liquid tube through an inflation / liquid port. The proximal end of the inflation / liquid tube is used to connect to an external inflation device.

[0014] The aforementioned multi-point temperature sensors are miniature thermocouples or fiber optic temperature sensors. Their temperature sensing nodes are in thermal contact with the inner wall of the electrode and are led out through wire holes to connect to an external thermometer or radiofrequency ablation device.

[0015] The aforementioned composite flexible catheter has a proximal fixation plate and a distal fixation plate arranged sequentially from the proximal end to the distal end; the proximal fixation plate has an inlet, an outlet, and an electrical wire hole; the distal fixation plate has a central hole for fixing the balloon cavity.

[0016] The aforementioned cooling circulation channel is provided with a near-end isolation plate and a far-end isolation plate in sequence from the near end to the far end; the near-end isolation plate is provided with a water outlet hole, a water inlet hole, a central hole and an electrical wire hole; the far-end isolation plate is provided with multiple water delivery holes and a central hole.

[0017] The aforementioned MRI-compatible transurethral non-invasive prostate-specific radiofrequency ablation electrode, a hollow cylindrical radiofrequency ablation electrode, is connected to an external radiofrequency transmitter via electrode wires. The radiofrequency transmitter operates at a frequency of 450-550 kHz, has an output power of 50-200 W, and outputs either continuous wave or pulsed wave modes. The power is adjusted in real-time based on feedback from multiple temperature sensors.

[0018] The overall working principle of this invention is as follows: A hollow cylindrical electrode acts as a radiofrequency energy radiator, connected to an external radiofrequency generator via a coaxial cable. Utilizing the capacitive coupling or resistive heating effect between the electrode's outer surface and surrounding tissue, an alternating electric field is generated within the tissue, causing tissue ions to vibrate and generate heat through friction, leading to protein denaturation and irreversible cell damage, thus achieving thermal coagulation ablation. Because the electrode is cylindrical and its length covers the entire hyperplastic area, its energy emission direction is radially isotropic, avoiding the "end ablation effect" caused by energy concentration at the tip of traditional needle-shaped electrodes. Simultaneously, a closed internal circulating coolant continuously flows inside the electrode, promptly removing heat from the inner wall through heat exchange, ensuring that the temperature of the electrode's outer surface in contact with the urethral mucosa remains within a safe range (e.g., ≤42℃), effectively protecting the urethral mucosa, submucosal tissue, and upper and lower urethral sphincters. Multi-point temperature sensors provide spatial distribution information, forming a triple safety protection system along with cooling flow regulation and radiofrequency power control. The combination of balloon anchoring and magnetic resonance guidance ensures that the electrode does not shift during treatment, and the ablation boundary is controllable.

[0019] All material selections, dimensional parameters, connection methods, and electrical characteristics not explicitly stated in the above technical solutions should be understood as employing conventional technical means well-known to those skilled in the art, and all are based on the premise of satisfying magnetic resonance compatibility and biocompatibility. The scope of protection claimed by this invention is not limited to the specific embodiments described above; any equivalent transformations or simple modifications made based on the core concept of this invention fall within the protection scope of this invention.

[0020] Beneficial Effects: This invention combines a hollow cylindrical electrode with an internal independent circulating cooling channel, allowing radio frequency energy to diffuse uniformly outward along the circumference of the electrode, completely eliminating the end ablation effect of traditional needle electrodes. Simultaneously, the coolant continuously flows inside the electrode, promptly removing heat from the urethral mucosa and surrounding tissues in close contact with the electrode. This ensures uniform thermal coagulation of deep hyperplastic glands while maintaining the urethral surface temperature within a physiologically safe range, preventing burns, carbonization, and future scarring and stenosis. Multi-point temperature sensors are tightly fitted along the catheter axis to the inner wall of the electrode and the outlet channel, forming a closed-loop feedback control with the external radio frequency generator. When the sensors detect that any temperature measurement point reaches a set safety threshold, the system automatically reduces power or stops output. This real-time dynamic control mechanism further ensures the thermal protection effect of the cooling system, making cooling and temperature measurement complementary rather than simply superimposed. An expandable balloon is placed at the tip of the catheter. After entering the bladder, it is inflated with air or fluid to precisely anchor the cylindrical electrode to the prostate treatment site. This not only prevents displacement caused by breathing or changes in body position, but also ensures stable adhesion between the electrode and the urethral mucosa adjacent to the hyperplastic tissue to be ablated, thereby ensuring uniform release of radiofrequency energy. In addition, with magnetic resonance compatibility design, all non-ferromagnetic components allow the entire device to complete catheter placement, positioning, temperature monitoring, and ablation assessment under magnetic resonance imaging. The combined effect of image guidance and balloon fixation significantly improves the repeatability and controllability of the treatment. Compared to existing devices that rely on puncture needles or shape memory alloy needles, this invention eliminates the need for any incision or puncture of the urethral mucosa, avoiding risks such as bleeding, perforation, and nerve damage. Compared to catheters using external irrigation cooling, this invention employs a completely closed internal circulation cooling circuit, eliminating the risk of increased tissue impedance and burns to adjacent structures caused by vapor leakage. Compared to devices with only a single-point temperature sensor, this invention's axial multi-point distributed temperature measurement can more comprehensively reflect the temperature field distribution around the electrodes and the urethral wall, providing a more reliable basis for closed-loop power adjustment. The synergistic and overall optimization of these technical features enable this invention to achieve a truly non-invasive, MRI-compatible, easy-to-operate, and rapid-recovery prostate radiofrequency ablation solution while ensuring treatment accuracy and safety. Attached Figure Description

[0021] Figure 1This is a schematic diagram of the overall structure of a balloon-loaded, magnetically responsive, transurethral non-invasive prostate-specific radiofrequency ablation electrode catheter in an embodiment of the present invention.

[0022] Figure 2 This is a partial view of the tip of a balloon-loaded, magnetically responsive, transurethral non-invasive prostate-specific radiofrequency ablation electrode catheter, as described in an embodiment of the present invention.

[0023] Figure 3 These are schematic diagrams of different cross-sections of the balloon-loaded, magnetic resonance-compatible transurethral non-invasive prostate-specific radiofrequency ablation electrode catheter in an embodiment of the present invention.

[0024] Figure 4 This is a mathematical simulation diagram illustrating the working principle of the magnetic resonance-compatible transurethral non-invasive prostate-specific radiofrequency ablation electrode in this embodiment of the invention.

[0025] Figure 5 This is a photograph of the actual effect of the transurethral non-invasive prostate-specific radiofrequency ablation electrode catheter with balloon and magnetic resonance compatible in an embodiment of the present invention.

[0026] Explanation of reference numerals in the attached diagram: 1-Composite flexible catheter; 2-Hollow cylindrical radiofrequency ablation electrode; 3-Expandable balloon; 4-Inlet tube; 5-Inflation / liquid tube; 6-Outlet tube; 7-Blind end; 8-Inflation / liquid port; 9-Distal fixation plate; 10-Balloon tube (Inflation / liquid tube and balloon tube are different sections of the same tube); 11-Outlet channel; 12-Inlet channel; 13-Multi-point temperature sensor; 14-Electrode wire; 15-Central hole; 16-Water inlet; 17-Distal isolation plate; 18-Electrical wire hole; 19-Inlet port; 20-Outlet port; 21-Proximal isolation plate; 22-Inlet; 23-Outlet; 24-Proximal fixation plate. Detailed Implementation

[0027] To make the technical solution, beneficial effects, and implementation steps of the present invention clearer and more explicit, a preferred embodiment and surgical procedure will be described in detail below. Those skilled in the art can make appropriate adjustments and implementations based on this description without departing from the core principles of the present invention.

[0028] A magnetic resonance-compatible, transurethral, ​​non-invasive radiofrequency ablation electrode for the prostate is disclosed. The electrode has an overall hollow cylindrical structure made of non-ferromagnetic material and includes a catheter body, a radiofrequency emission assembly, a cooling circulation assembly, a multi-point temperature measurement assembly, a front-end anchoring assembly, and a rear-end connection assembly. The catheter body is a flexible or semi-rigid hollow tube with an outer diameter adapted to the male urethral diameter. The proximal end connects to a radiofrequency generator and a coolant circulation pump, while the distal end is inserted into the prostatic urethra. The radiofrequency emission assembly, located at the distal treatment section of the catheter body, is a cylindrical electrode with a continuous conductive layer on its outer surface, covering the enlarged prostate region along the axial length of the catheter. Internally, it is connected to a coaxial cable or twisted pair to convert the high-frequency electrical energy output from the radiofrequency generator into a radially uniformly emitted electromagnetic field at 360°, producing a thermal coagulation effect on the surrounding prostate tissue. Insulated transition sections are provided at both the distal and proximal ends of the cylindrical electrode to define the energy emission boundary and avoid unintended thermal damage to the bladder neck and urethral sphincter.

[0029] The cooling circulation assembly includes an inlet channel, an outlet channel, and an external circulation pipeline. The inlet channel and the outlet channel are axially arranged inside the main body of the conduit and are connected by a water inlet. The coolant is driven by an external circulation pump, flows through the inlet channel through the entire cylindrical electrode coverage area, and then flows back to the external cooling device through the outlet channel, forming a completely closed internal circulation cooling loop. Its circulation flow rate is dynamically adjusted by the external control system based on real-time temperature feedback.

[0030] The multi-point temperature measurement component includes at least three temperature sensors distributed along the axial direction of the catheter on the inner wall of the cylindrical electrode and in the outlet channel. The temperature sensors are fiber Bragg grating sensors or resistive temperature sensors, and their leads are made of non-ferromagnetic materials. The sensors are arranged at equal or non-equal intervals along the treatment section of the electrode to monitor the temperature at the proximal, middle, and distal ends of the electrode, as well as the return temperature of the coolant in the outlet channel. The signal lines of all temperature sensors are led through the inside of the catheter body to the proximal interface and electrically connected to the temperature acquisition module of the external radio frequency generator. The temperature acquisition module reads the temperature value of each measurement point in real time and transmits it to the control unit. When any measurement point reaches a preset safety threshold, the control unit automatically reduces the radio frequency output power or interrupts the energy output, forming a closed-loop temperature control system.

[0031] The front-end anchoring assembly includes an inflatable balloon and a balloon tube; the balloon is fixed to the distal end of the catheter body and, when not inflated, fits tightly against the outer wall of the catheter body for easy insertion through the urethra; the balloon is connected to an external inflation device through the balloon tube, which extends along the inside of the catheter body to the proximal interface; after the catheter is inserted into the bladder, gas or magnetic resonance compatible liquid is injected into the balloon through the balloon tube, causing the balloon to expand radially to a diameter larger than the inner diameter of the bladder neck, thereby locking the balloon at the bladder neck when the catheter is pulled back, accurately anchoring the cylindrical electrode in the prostatic urethra, and ensuring that the outer wall of the electrode remains stably attached to the urethral mucosa of the adjacent hyperplastic prostatic tissue;

[0032] The catheter body, cylindrical electrode, coolant channel, temperature sensor, balloon, and all connectors are made of non-ferromagnetic materials, including but not limited to pure titanium, titanium alloy, copper alloy (non-magnetic), stainless steel (austenitic non-magnetic), platinum-iridium alloy, ceramics, polyetheretherketone, polytetrafluoroethylene, silicone rubber, and medical-grade polymer materials, to ensure that the entire device has no significant magnetization interference effect, no eddy current heating, and no image artifacts in the magnetic resonance imaging environment, and meets the requirements for real-time positioning, temperature measurement, and ablation assessment under magnetic resonance guidance.

[0033] Furthermore, the conductive layer surface of the cylindrical electrode may be provided with annular grooves or micropore structures to increase the effective surface area, reduce contact impedance, and promote uniform emission of radio frequency energy.

[0034] Furthermore, the balloon is made of a non-ferromagnetic flexible polymer material, and its surface may be provided with anti-slip textures or protrusions to enhance anchoring stability.

[0035] Furthermore, the temperature sensor is tightly attached to the inner wall of the electrode using thermally conductive grease or adhesive, and the sensor is wrapped with an insulating and thermally conductive layer to reduce temperature measurement delay and improve response speed.

[0036] Furthermore, the outer surface of the catheter body is provided with scale marks or imaging marks. The imaging marks are made of non-ferromagnetic metal rings or gadolinium-containing compound coatings, which are used to clearly display the axial position and rotational orientation of the electrodes under magnetic resonance or ultrasound imaging.

[0037] Furthermore, the back-end connection assembly includes an RF connector, a coolant quick connector, and a temperature signal connector. Each connector is integrated on a multi-port interface socket, which is fixed to the proximal end of the conduit body for quick connection to an external RF generator, a circulating coolant pump, and a temperature monitor.

[0038] Example 1

[0039] This embodiment provides a magnetic resonance-compatible, transurethral, ​​non-invasive radiofrequency ablation electrode specifically for the prostate, the overall structure of which is as follows: Figure 1 , Figure 2As shown, it includes a composite flexible conduit 1, a hollow cylindrical radiofrequency ablation electrode 2, a cooling circulation channel, an expandable balloon 3, and a multi-point temperature sensor 13 disposed on the flexible conduit.

[0040] The composite flexible catheter 1 is made of medical-grade non-ferromagnetic polymer materials, such as polyetheretherketone (PEEK), polytetrafluoroethylene (PTFE), medical-grade silicone, or polyvinyl chloride (PVC). These materials possess excellent electrical insulation, biocompatibility, high-temperature resistance, and magnetic resonance compatibility. The total length of the catheter is approximately 200-350 mm, and the outer diameter is approximately 4-8 mm. The distal end of the catheter is a smooth, blunt blind end 7, which effectively reduces resistance during catheter advancement and minimizes puncture and friction damage to the urethral mucosa. The proximal end of the catheter has multiple interfaces for connecting to a radiofrequency generator, a cooling circulation system, and an infusion device.

[0041] A hollow cylindrical radiofrequency ablation electrode 2 is embedded in the distal outer wall of the composite flexible catheter 1, specifically in the prostate working area of ​​the catheter. This electrode has a cylindrical structure, 20-50 mm in length, 4-8 mm in outer diameter, and 0.1-0.5 mm in wall thickness. It is made of a non-ferromagnetic, high-quality conductive metal or alloy, such as copper, 316L stainless steel, pure titanium, or titanium alloy. The entire outer surface of the electrode wall forms a complete 360° circumferential radiofrequency emission surface. The surface is polished, allowing radiofrequency energy to diffuse uniformly outward along the radial direction of the electrode, eliminating the end-ablation effect of traditional needle electrodes and avoiding puncture or thermal damage to the urethral mucosa, sphincter, neurovascular bundle, and anterior rectal wall. Electrode 2 is connected to an external radiofrequency transmitter via electrode wire 14. Electrode wire 14 is covered with an insulating layer (polytetrafluoroethylene) and runs longitudinally along the inner wall of the catheter. Its tip is laser-welded to the inner wall of electrode 2.

[0042] like Figure 3 , Figure 4As shown, the hollow cylindrical radiofrequency ablation electrode 2 has independent coolant inflow and return channels inside, forming a cooling circulation channel. Specifically, the cooling circulation channel includes an inlet channel 12 and an outlet channel 11 located within the conduit, as well as an inlet pipe 4 and an outlet pipe 6 connected to the inlet and outlet channels, respectively. The inlet channel 12 and the outlet channel 11 are double-layered coaxial or parallel tubular structures, and they are connected in the distal region inside the electrode through multiple water inlets 16 opened on the distal isolation plate 17 to form a circulation loop. The inlet pipe 4 and the outlet pipe 6 are medical-grade synthetic material tubes (polyurethane or silicone tubes), with standard Luer connectors at the proximal ends, which are connected to a peristaltic pump and a constant temperature water tank or ice water container, respectively. During operation, an external peristaltic pump drives coolant (sterile saline or purified water, temperature controlled between 0-20℃) into the inlet channel 12 through the inlet pipe 4. After flowing to the distal end of the electrode, it enters the outlet channel 11 through the water outlet 16, and then flows back to the cooling medium source through the outlet pipe 6, forming a closed loop. The flow rate of the circulating fluid can be adjusted by the peristaltic pump as needed. This circulation can continuously remove the resistive heat generated in the tissue adjacent to the electrode, effectively protecting the urethral mucosa, submucosal tissue, and upper and lower sphincter muscles from heat damage.

[0043] An expandable balloon 3 is disposed at the distal end of the catheter (i.e., distal to the hollow cylindrical radiofrequency ablation electrode 2). The expandable balloon 3 is made of an elastic medical polymer material (silicone rubber or polyurethane), with a wall thickness of approximately 0.02-0.1 mm, exhibiting good burst pressure resistance and biocompatibility, and is made of a non-ferromagnetic material. The expandable balloon 3 is gas or liquid inflatable, and its expansion and contraction are achieved through the inflation / liquid tube 5, the balloon tube 10, and the inflation / liquid port 8. Specifically, the composite flexible catheter 1 contains a balloon tube 10, the distal end of which is connected to the expandable balloon 3, and the proximal end of the balloon tube 10 is connected to the distal inflation / liquid tube 5 through the inflation / liquid port 8. The proximal end of the inflation / liquid tube 5 is used to connect to an external syringe or pressure pump. After the catheter is inserted through the urethra and the hollow cylindrical electrode 2 reaches the prostate treatment site, sterile air or saline is injected into the expandable balloon 3 to expand it. The expanded balloon is located in the bladder and gently anchored to the internal urethral orifice of the bladder neck, thereby ensuring that the hollow cylindrical radiofrequency ablation electrode 2 maintains a stable fit with the urethral mucosa adjacent to the hyperplastic prostate tissue, preventing electrode displacement caused by changes in body position or tissue peristalsis.

[0044] To achieve real-time temperature monitoring and feedback control during the ablation process, multiple temperature sensors 13 are distributed along the axial direction of the composite flexible catheter 1. In this embodiment, the multiple temperature sensors 13 employ miniature thermocouples (K-type, T-type, or N-type) or fiber optic temperature sensors. Their temperature sensing nodes are in thermally conductive contact with the inner wall of the hollow cylindrical radiofrequency ablation electrode 2, and are fixed between the outer wall of the outlet channel 11 and the inner wall of the electrode 2 using medical high-temperature resistant adhesive. The sensor signal lines are led out through the wire hole 18 and connected to an external thermometer or radiofrequency ablation device. Specifically, the probes of the multiple temperature sensors 13 are respectively set at different positions along the axial direction of the catheter (e.g., corresponding to the proximal end, middle, distal end of the electrode, and the inlet and outlet channels), extending parallel to the electrode wires 14, converging into the electrode connection cable through the wire hole 18 of the proximal isolation plate 21, and then leading out through the proximal fixing plate 24. The sensors can monitor the electrode surface temperature and the inflow and outflow temperatures of the coolant in real time, and transmit the data back to the external controller.

[0045] The controller incorporates a built-in comparison circuit or algorithm (such as PID control or a threshold comparator) to form a closed-loop feedback control system. When the temperature at any measuring point exceeds a preset safety threshold (typically set to the maximum tolerable temperature of the urethral mucosa, 40°C), the controller prioritizes issuing a command to increase the speed of the peristaltic pump to enhance the cooling effect. If the temperature continues to rise, it automatically reduces the output power of the radio frequency generator or suspends output. Once the temperature drops back to the safe range, the power output is automatically restored. This closed-loop feedback mechanism ensures that the urethral mucosa temperature is always maintained within the physiologically safe range of 5-40°C, preventing thermal damage to the urethral mucosa.

[0046] The composite flexible catheter 1 also contains multiple plates for fixation and isolation, arranged sequentially from proximal to distal. Specifically, the catheter contains, from proximal to distal, a proximal fixation plate 24, a proximal isolation plate 21, a distal isolation plate 17, and a distal fixation plate 9, with the following structures: Figure 2 and Figure 3 As shown.

[0047] A proximal fixing plate 24 is disposed at the proximal end (external end) of the conduit, and has an inlet 22, an outlet 23, and an electrical wire hole 18 thereon. The inlet 22 is used to fix the proximal end of the inlet pipe 4, the outlet 23 is used to fix the proximal end of the outlet pipe 6, and the electrical wire hole 18 is used to accommodate and lead out the electrode connection cable and the signal line of the temperature sensor.

[0048] A proximal isolation plate 21 is disposed in the proximal region of the cooling circulation channel, located on the distal side of the proximal fixing plate 24. The proximal isolation plate 21 is provided with a water outlet 20, a water inlet 19, a central hole 15, and an electrical wire hole 18. The water inlet 19 is used to fix the proximal end of the liquid inlet channel 12, the water outlet 20 is used to fix the proximal end of the liquid outlet channel 11, the central hole 15 allows the balloon tube 10 to pass through, and the electrical wire hole 18 allows the electrode wire 14 and the temperature sensor signal line to pass through.

[0049] The distal isolating plate 17 is located in the distal region of the cooling circulation channel, on the distal side of the proximal isolating plate 21, inside the distal end of the hollow cylindrical radiofrequency ablation electrode 2. The distal isolating plate 17 has multiple circumferentially distributed water inlets 16 and a central hole 15. The water inlets 16 are typically 4-8 in number, with a diameter of 0.3-0.8 mm, used to connect the inlet channel 12 and the outlet channel 11, allowing coolant to flow from the inlet channel into the outlet channel at the distal end of the electrode. The central hole 15 is used to fix the distal end of the balloon tube 10.

[0050] The distal fixation plate 9 is located at the distal end of the catheter (near the blind end 7), on the distal side of the distal isolation plate 17. The distal fixation plate 9 has a central hole 15 for fixing the distal end of the balloon cavity 10 and preventing coolant leakage and gas ingress.

[0051] All components of the entire device—including the composite flexible catheter 1, the hollow cylindrical radiofrequency ablation electrode 2, the expandable balloon 3, and the leads of the multi-point temperature sensor 13—are made of non-ferromagnetic materials. The electrodes are made of non-magnetic or weakly magnetic metals (copper, 316L stainless steel, pure titanium, or titanium alloy), the leads are made of pure copper with a polytetrafluoroethylene (PTFE) insulating layer, the balloon is made of silicone or polyurethane, and the catheter is made of PEEK or PTFE. This gives the entire catheter system complete MRI compatibility, enabling catheter placement guidance, real-time positioning and temperature monitoring, and post-ablation assessment under MRI imaging. During use, it can be applied to the patient's thigh or lower back skin with MRI-compatible distributed electrode plates to form a monopolar radiofrequency circuit.

[0052] The radiofrequency generator used in this embodiment operates at a frequency of 450-550 kHz, with a maximum output power of 50-200W. The output mode can be continuous wave or pulsed wave, and the power can be adjusted in real time based on feedback from the multi-point temperature sensor 13. In actual ablation treatment, an electrode of appropriate length (20-50 mm) can be selected based on preoperative imaging measurements. The initial power and ablation time are set, and the radiofrequency output is initiated with the cooling cycle on. Real-time temperature monitoring ensures the safety of the urethral mucosa. After ablation, the radiofrequency output is first turned off, and the cooling cycle continues to run for 2-5 minutes. Once the temperature drops to a safe range, the balloon is aspirated and the catheter is slowly withdrawn.

[0053] The aforementioned hollow cylindrical electrode, internal circulating cooling, multi-point temperature sensors, and expandable balloon do not work independently but rather cooperate to form a unified and synergistic system. The expandable balloon stably presses the cylindrical electrode against the inner wall of the prostatic urethra, creating a uniform and tight electrical contact interface between the outer surface of the electrode and the urethral mucosa adjacent to the hyperplastic tissue, providing the prerequisite for 360° radial energy emission. The circulating coolant inside the electrode continuously removes heat from the electrode-tissue interface, keeping the temperature of the urethral mucosa in contact with the electrode within a physiologically safe range. This allows the radiofrequency generator to deliver energy to deeper tissues at higher power or for longer periods without burning the superficial layers. The multi-point temperature sensors monitor the temperature at different axial positions of the electrode in real time. If any point exceeds the limit, the power or flow rate is adjusted accordingly to prevent tissue carbonization or increased impedance due to local hot spots. In contrast, if only a cylindrical electrode is used without cooling, the urethral mucosa will inevitably be overheated and burned; if only cooling is used without balloon fixation, the electrode will not make uniform contact with the tissue, and the cooling effect will not be able to cover all areas; if only a temperature sensor is used without closed-loop control, it will be unable to dynamically respond to tissue differences. These features are interdependent and work together to achieve precise, uniform, and controllable ablation of prostatic hyperplasia tissue under non-invasive transurethral conditions, while simultaneously protecting the urethral mucosa and the upper and lower sphincter muscles. This is a technical effect that cannot be achieved by any single feature or simple combination of features.

[0054] The following is an exemplary use of the radiofrequency ablation electrode to illustrate its working principle. This method of operation does not constitute a limitation on the product structure itself.

[0055] During the clinical procedure, the patient is placed in the lithotomy position and given topical urethral anesthesia or spinal anesthesia. A cystoscope can be inserted transurethral to observe the length of the prostatic urethra, the location of the verumontanum, and the morphology of the bladder neck. Prostatic volume and hyperplasia sites are measured using ultrasound or MRI fusion imaging. The radiofrequency ablation target area is marked, and the electrode catheter insertion depth and balloon anchoring point are determined. The radiofrequency ablation catheter, coated with conductive adhesive, is inserted into the urethra under direct vision, or under real-time MRI monitoring, ensuring the catheter tip passes through the internal urethral orifice of the bladder neck into the bladder. Sufficient sterile saline or gas is injected into the distal balloon, and the catheter is gently pulled to bring the balloon close to the internal urethral orifice of the bladder neck. The cooling circulation pump is activated to perfuse the inner surface circuit of the tubular electrode with cryogenic saline. The ablation power and time are set, with a target temperature of 80-100℃ for the ablation area, or ablation is performed zone by zone according to the pre-operative plan, with real-time monitoring of tissue impedance changes and temperature feedback. The ablation range is assessed in real-time based on MRI images to avoid heat diffusion to the superior and inferior sphincter muscles, prostatic capsule, or rectal wall. Continuously monitor the cooling circuit outlet temperature and bladder filling status. Once the impedance stabilizes and the target area reaches the planned volume, gradually reduce the power to terminate the radiofrequency output, maintaining cooling perfusion for 3-5 minutes for tissue cooling. Empty the balloon, slowly withdraw the radiofrequency catheter, and observe the urethral mucosa for any damage or bleeding; cystoscopy can be reinserted or direct visualization can be used to examine the patency of the prostatic urethra and for any ablation wounds; a suitable silicone catheter can be left in place for 1-3 days.

[0056] The technical solutions of the embodiments of the present invention have been described above with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

Claims

1. A magnetic resonance-compatible, transurethral, ​​non-invasive radiofrequency ablation electrode for the prostate, characterized in that, The device includes a composite flexible catheter (1), a hollow cylindrical radiofrequency ablation electrode (2), a cooling circulation channel, an expandable balloon (3), and a multi-point temperature sensor (13) disposed on the composite flexible catheter. The hollow cylindrical radiofrequency ablation electrode (2) has an independent coolant inflow channel and a coolant return channel inside, forming a cooling circulation channel. The expandable balloon (3) is disposed at the front end of the composite flexible catheter (1) and is used to expand in the bladder to make the electrode aligned and attached to the prostate tissue. The multi-point temperature sensor (13) is distributed along the axial direction of the composite flexible catheter and is used to monitor the temperature of the electrode, the urethral wall, and the cooling water in real time. The wires of the composite flexible catheter (1), the hollow cylindrical radiofrequency ablation electrode (2), the expandable balloon (3), and the multi-point temperature sensor (13) are all made of non-ferromagnetic materials.

2. The magnetic resonance-compatible transurethral non-invasive prostate-specific radiofrequency ablation electrode according to claim 1, characterized in that, The composite flexible catheter (1) is made of medical-grade polymer material, and its distal end is a smooth, blunt blind end (7).

3. The magnetic resonance-compatible transurethral non-invasive prostate-specific radiofrequency ablation electrode according to claim 1, characterized in that, The hollow cylindrical radiofrequency ablation electrode (2) has a length of 20-50 mm and an outer diameter of 4-8 mm. It adopts a circular tube structure, and the radiofrequency energy diffuses outward uniformly along the radial direction of the electrode, thus avoiding the end ablation phenomenon of the electrode.

4. The magnetic resonance-compatible transurethral non-invasive prostate-specific radiofrequency ablation electrode according to claim 1, characterized in that, The cooling circulation channel includes an inlet channel (12) and an outlet channel (11) disposed in a composite flexible conduit, as well as an inlet pipe (4) and an outlet pipe (6) respectively connected to the inlet channel and the outlet channel; the coolant inflow channel and the return channel are connected inside the electrode to form a circulation loop, and the coolant is driven to flow through an external coolant circulation system.

5. The magnetic resonance-compatible transurethral non-invasive prostate-specific radiofrequency ablation electrode according to claim 1, characterized in that, The expandable balloon (3) is made of elastic medical polymer material and is a gas or liquid-filled balloon. The composite flexible catheter (1) is provided with a balloon tube (10). The distal end of the balloon tube (10) is connected to the expandable balloon (3). The proximal end of the balloon tube (10) is connected to the inflation / liquid tube (5) through the inflation / liquid hole (8). The proximal end of the inflation / liquid tube (5) is used to connect to an external inflation device.

6. The magnetic resonance-compatible transurethral non-invasive prostate-specific radiofrequency ablation electrode according to claim 1, characterized in that, The multi-point temperature sensor (13) is a miniature thermocouple or fiber optic temperature sensor. Its temperature measuring node is in thermal contact with the inner wall of the electrode and is led out through the wire hole (18) to connect to an external thermometer or radiofrequency ablation device.

7. The magnetic resonance-compatible transurethral non-invasive prostate-specific radiofrequency ablation electrode according to claim 1, characterized in that, The composite flexible catheter is provided with a proximal fixation plate (24) and a distal fixation plate (9) in sequence from the proximal end to the distal end; the proximal fixation plate (24) is provided with an inlet (22), an outlet (23) and an electrical wire hole (18); the distal fixation plate (9) is provided with a central hole (15) for fixing the balloon cavity (10).

8. The magnetic resonance-compatible transurethral non-invasive radiofrequency ablation electrode for the prostate as described in claim 1, characterized in that, The cooling circulation channel is provided with a near-end isolation plate (21) and a far-end isolation plate (17) in sequence from the near end to the far end; the near-end isolation plate (21) is provided with a water outlet (20), a water inlet (19), a central hole (15) and an electrical wire hole (18); the far-end isolation plate (17) is provided with a plurality of water supply holes (16) and a central hole (15).

9. The magnetic resonance-compatible transurethral non-invasive radiofrequency ablation electrode for the prostate according to any one of claims 1 to 8, characterized in that, The hollow cylindrical radio frequency ablation electrode (2) is connected to an external radio frequency transmitter via an electrode wire (14). The radio frequency transmitter operates at a frequency of 450-550 kHz, has an output power of 50-200 W, and operates in a continuous wave or pulse wave mode. The power is adjusted in real time based on feedback from a multi-point temperature sensor (13).

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