Mri-compatible implantable medical device and neurostimulation system

Abstract

This invention relates to the field of medical devices, and more particularly to an MRI-compatible implantable medical device and a neurostimulation system. The implantable medical device features a dual-reliability design, capable of entering a first operating mode via an external first mode command. The controller monitors the magnetic field strength; when the magnetic field strength exceeds a safety threshold and the duration 'a' is greater than a first time threshold, the controller switches to a second operating mode, in which the MRI-compatible function is activated. The controller can also directly enter the second operating mode and activate the MRI-compatible function based on an external second mode command. When the magnetic field strength is less than the safety threshold and the duration 'b' is greater than the second time threshold, the controller exits the second operating mode and deactivates the MRI-compatible function. In this invention, activating the MRI-compatible function reduces the impact of the MRI environment on the controller's pulse output, ensuring therapeutic efficacy for patients and improving safety.

Description

Technical Field

[0001] This invention relates to the field of medical devices, and more particularly to an MRI-compatible implantable medical device and a neurostimulation system. Background Technology

[0002] Currently, there are many types of implantable medical devices, such as pacemakers and defibrillators, implantable neurostimulators, and implantable muscle stimulators. Implantable medical devices generally consist of an implanted device and an external control device, which exchange information via two-way wireless communication.

[0003] In existing technologies, implantable neurostimulators include an implantable pulse generator and stimulating electrodes. The implantable pulse generator emits stimulation pulses of a specific frequency, which are then delivered to specific target points via the stimulating electrodes, thereby improving the patient's symptoms. However, strong magnetic fields, such as those encountered during magnetic resonance imaging (MRI), can affect the electrical performance of the controller, thus impacting the treatment outcome and posing safety risks. Summary of the Invention

[0004] In view of this, the present invention provides an MRI-compatible implantable medical device and a neurostimulation system. The implantable medical device has a dual reliability design, which can reduce the impact of the MRI environment on the controller and improve safety.

[0005] This invention provides an MRI-compatible implantable medical device, including a controller;

[0006] The controller is used to receive a first mode instruction and a second mode instruction, so as to enter a first working mode based on the first mode instruction, or to enter a second working mode based on the second mode instruction.

[0007] In the first working mode, if the controller detects that the duration 'a' of the external magnetic field strength exceeding the safety threshold is greater than the first time threshold, then it switches to the second working mode.

[0008] In the second working mode, the controller enables timing and MRI compatibility functions. When the duration b of the second working mode is greater than the second time threshold and the external magnetic field strength is less than the safety threshold, the controller exits the second working mode and disables timing and MRI compatibility functions.

[0009] Preferably, in some embodiments of the present invention, the controller is configured as follows:

[0010] A magnetic field sensing unit, wherein the magnetic field sensing unit is used to monitor the strength of the external magnetic field;

[0011] A clock unit, which is used to generate the durations a and b.

[0012] Preferably, in some embodiments of the present invention, the controller is used to monitor the duration c of the external magnetic field detected by the magnetic field sensing unit, and when the duration c is greater than a third time threshold, the controller marks the magnetic field sensing unit as abnormal.

[0013] Preferably, in some embodiments of the present invention, the controller is configured to receive a marking instruction, and the controller marks the magnetic field sensitive unit as abnormal according to the marking instruction.

[0014] Preferably, in some embodiments of the present invention, the controller is configured to receive a third mode instruction, wherein when the magnetic field sensing unit is abnormal, the controller enters the second working mode according to the second mode instruction and exits the second working mode according to the third mode instruction.

[0015] Preferably, in some embodiments of the present invention, enabling the MRI compatibility function includes: enabling the current protection function, enabling the real-time monitoring pulse transmission function, and disabling the timed stimulation function;

[0016] Disabling the MRI-compatible functions includes: disabling the current protection function, disabling the real-time pulse output monitoring function, and restoring the timed stimulation function.

[0017] Preferably, in some embodiments of the present invention, the controller is provided with a recording unit, which is used to record the start time of the second working mode, the duration b, and the exit method of the second working mode.

[0018] A second aspect of the present invention provides an MRI-compatible neurostimulation system, comprising an external programming device and the aforementioned MRI-compatible implantable medical device;

[0019] The external programming device is used to send MRI mode control commands to the implantable medical device, the MRI mode control commands including the first mode command and the second mode command.

[0020] Preferably, in some embodiments of the present invention, the external programming device includes the following steps before sending the MRI mode control command:

[0021] Send MRI pattern detection instructions to the implantable medical device;

[0022] The implantable medical device sends product model information and impedance test information to the external programming device according to the MRI mode detection command.

[0023] Preferably, in some embodiments of the present invention, the external programming device is pre-configured with a database that associates product models with magnetic resonance imaging conditions;

[0024] The external programmed device is used to determine whether the impedance test information is abnormal.

[0025] If so, an error message will be displayed;

[0026] If not, then match the corresponding magnetic resonance conditions according to the product model.

[0027] The beneficial effects of the subject name provided by this invention include:

[0028] This invention provides an MRI-compatible implantable medical device and a neurostimulation system. The implantable medical device features a dual-reliability design, capable of entering a first operating mode via an external first mode command. The controller monitors the magnetic field strength; when the magnetic field strength exceeds a safety threshold and the duration 'a' is greater than a first time threshold, the controller switches to a second operating mode, activating the MRI-compatible function. Alternatively, the controller can directly enter the second operating mode and activate the MRI-compatible function based on an external second mode command. When the magnetic field strength is less than the safety threshold and the duration 'b' is greater than the second time threshold, the controller exits the second operating mode and deactivates the MRI-compatible function. In this invention, activating the MRI-compatible function reduces the impact of the MRI environment on the controller's pulse output, ensuring therapeutic efficacy for patients and improving safety. Attached Figure Description

[0029] The above and other objects, features and advantages of the present invention will become clearer from the following description of embodiments of the invention with reference to the accompanying drawings, in which:

[0030] Figure 1 This is a schematic diagram of the workflow of the MRI-compatible neurostimulation system in this invention.

[0031] Figure 2 This is another schematic diagram of the workflow of the MRI-compatible neurostimulation system in this invention.

[0032] Figure 3 This is a schematic diagram of the workflow of the external programmed device in this invention.

[0033] Figure 4 This is a schematic diagram of the MRI listening mode workflow of the implantable medical device in this invention.

[0034] Figure 5 This is a schematic diagram of the workflow of the MRI protection mode of the implantable medical device in this invention.

[0035] Figure 6 This is another schematic diagram of the workflow of the MRI-compatible neurostimulation system in this invention.

[0036] Figure 7 This is a schematic diagram of another working process of the external programmable device in this invention.

[0037] Figure 8 This is a schematic diagram of another workflow of the MRI protection mode of implantable medical devices in this invention. Detailed Implementation

[0038] The present invention is described below based on embodiments, but the invention is not limited to these embodiments. In the detailed description of the invention below, certain specific details are described in detail. Those skilled in the art will fully understand the invention even without these details. To avoid obscuring the essence of the invention, well-known methods, processes, flows, elements, and circuits are not described in detail.

[0039] Unless the context explicitly requires it, the terms "comprising," "including," and similar terms throughout the application should be interpreted as encompassing rather than exclusive or exhaustive; that is, meaning "including but not limited to." In the description of this invention, it should be understood that terms such as "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0040] This invention provides an MRI-compatible implantable medical device and an MRI-compatible neurostimulation system. The neurostimulation system includes an external programming device and the implantable medical device. Before activating the MRI mode, the external programming device can check the implantable medical device. If no abnormalities are found, the device controls the implantable medical device to activate either the MRI listening mode or the MRI protection mode. The implantable medical device in this invention includes an implantable pulse generator, which is equipped with a controller. The implantable pulse generator can be abbreviated as IPG.

[0041] Figure 1 This is a schematic diagram of the workflow of the MRI-compatible neurostimulation system in this invention.

[0042] like Figure 1 As shown, the workflow of an MRI-compatible neurostimulation system includes:

[0043] S10, the external programmable device sends an MRI mode detection command to the IPG, and receives the product model information and impedance test information returned by the IPG based on the MRI mode detection command. If the external programmable device determines that the impedance test information is abnormal, it issues an abnormality prompt. If it determines that the impedance test information is normal, it further determines the conditions suitable for MRI examination based on the product model information and sends the first mode command to the IPG.

[0044] Product model information includes IPG model, electrode model, extension lead model, electrode adapter information, etc. Impedance test information includes shielding integrity testing of electrodes and extension leads, and path integrity testing during pulse output, such as the connection between the top cover and the electrodes. The external programmed device has a pre-set database that associates product models with MRI conditions; the corresponding MRI conditions can be determined based on the product model information. The data in the database can be set and modified.

[0045] S20, the IPG receives the first mode instruction and enters the first working mode. When the magnetic field strength is detected to exceed the safety threshold and the duration a is greater than the first time threshold, it switches to the second working mode.

[0046] In this invention, the first working mode is an MRI listening mode, used to monitor whether an MRI examination has started. If the duration 'a' is greater than a first time threshold, the start of the MRI examination is confirmed. Limiting the duration can avoid misjudgment caused by changes in the patient's environment.

[0047] S30, the IPG enters the second working mode, enabling timing and MRI compatibility functions. When the duration b of the second working mode is greater than the second time threshold and the magnetic field strength is less than the safety threshold, the second working mode is exited, and the timing and MRI compatibility functions are turned off.

[0048] The second working mode is also the MRI protection mode. Entering the second working mode is considered the start of the MRI examination. The duration b of the second working mode is also the timer for the MRI examination. In this invention, the IPG adopts a dual reliability design with listening and protection modes. The MRI compatibility function reduces the impact of the MRI environment on the controller's pulse output, ensuring the treatment effect on the patient and improving safety.

[0049] Figure 2 This is another schematic diagram of the workflow of the MRI-compatible neurostimulation system in this invention. Figure 2 and Figure 1 The difference in the process is that the external programming device sends a second mode command to the IPG, and the IPG directly enters the second working mode (MRI protection mode).

[0050] like Figure 2 As shown, another workflow of an MRI-compatible neurostimulation system includes:

[0051] S10a, the external programmable device sends an MRI mode detection command to the IPG, and receives product model information and impedance test information returned by the IPG based on the MRI mode detection command. If the external programmable device determines that the impedance test information is abnormal, it issues an abnormality prompt. If it determines that the impedance test information is normal, it further determines the conditions suitable for MRI examination based on the product model information and sends a second mode command to the IPG.

[0052] S20a, the IPG enters the second working mode, enabling timing and MRI compatibility functions. When the duration b of the second working mode is greater than the second time threshold and the magnetic field strength is less than the safety threshold, the second working mode is exited, and the timing and MRI compatibility functions are turned off.

[0053] exist Figure 1 , 2 In the workflow, S10 and S10a are executed by an external programmable device, while S20, S30, and S20a are executed by the IPG controller. In some other embodiments, timing and magnetic field strength detection can also be performed by an external programmable device, and the user controls the IPG operation based on the timing and magnetic field strength.

[0054] Figure 3 This is a schematic diagram of the workflow of the external programmed device in this invention.

[0055] An external programming device is used to send MRI mode control commands to implantable medical devices. These commands include first mode commands and second mode commands to control the implantable medical device to enter either the first or second operating mode. The external programming device stores various implantable product information, including the implantable pulse generator model, electrode model, extension lead model, whether an adapter is used, and adapter information, which can be entered by the physician during surgery. Before sending the MRI mode control commands, the external programming device sends an MRI mode detection command to the implantable medical device. Based on this command, the implantable medical device sends its product model information and impedance test information to the external programming device to determine if its impedance is abnormal and to determine suitable MRI conditions.

[0056] like Figure 3 As shown, the specific workflow of the external programmed device in S10 above includes:

[0057] S11, the external programming device sends an MRI mode detection command to the IPG to exchange MRI compatibility information of the implantable product (IPG), which includes product model information and impedance test information.

[0058] S12, the external programming device receives the implanted product model information (including IPG model, electrode model, extension lead model, electrode adapter information, etc.) and impedance test information returned by the IPG.

[0059] S13, determine if there is an impedance abnormality;

[0060] If so, execute S14 and issue an impedance abnormality warning;

[0061] If not, proceed to S15. Based on the model information and / or impedance information, the external programmed device determines the MRI examination conditions. Examination conditions include whole body / head, 1.5T / 3.0T, incompatibility, etc., and provides a prompt for the determined MRI examination conditions.

[0062] S16, the external programming device sends the first mode command to the IPG, causing the IPG to enter the MRI listening mode.

[0063] S17, the external programming device sends a second mode command to put the IPG into MRI protection mode. S16 and S17 are executed at a choice. In the above S10, the external programming device only executes S16.

[0064] Figure 4 This is a schematic diagram of the MRI listening mode workflow of the implantable medical device in this invention.

[0065] The external programming device executes the above-described S16 to send a first mode command to the IPG. The IPG controller receives the first mode command and enters the MRI listening mode, which is also the first working mode. In the first working mode, if the controller detects that the duration 'a' of the external magnetic field strength exceeding the safety threshold is greater than a first time threshold, it switches to the second working mode. In this invention, the controller includes a magnetic field sensing unit and a clock unit. The magnetic field sensing unit is used to monitor the external magnetic field strength, and the clock unit is used to generate the duration 'a'.

[0066] like Figure 4 As shown, after the IPG receives the first mode instruction, the specific workflow of S20 above includes:

[0067] S21, IPG enters MRI listening mode.

[0068] S22, a magnetic field sensitive unit that monitors the strength of the external magnetic field.

[0069] S23, determine whether the external magnetic field strength exceeds the safety threshold, which can be determined by the controller based on the external magnetic field strength monitored by the magnetic field sensing unit;

[0070] If so, execute S24, and the clock unit will start timing;

[0071] If not, return to step S22, and the magnetic field sensing unit will continue to monitor the external magnetic field strength.

[0072] S25, determine whether the duration a is greater than the first time threshold, and the clock unit timing duration is the duration a.

[0073] If so, execute S26, and the IPG enters the MIR protection mode. The IPG actively switches from the first operating mode to the MIR protection mode; the MRI protection mode is also the second operating mode.

[0074] In this invention, if the external magnetic field strength falls below a safety threshold after the clock unit starts timing, the timing is reset and stopped. When the external magnetic field strength exceeds the safety threshold, timing is restarted.

[0075] Figure 5 This is a schematic diagram of the workflow of the MRI protection mode of the implantable medical device in this invention.

[0076] In this invention, the external programmed device executes the above-mentioned S17 to send a second mode command to the IPG. The controller receives the second mode command and enters the second working mode, or can actively switch to the second working mode from the first working mode. In the second working mode, the controller activates the timing and MRI compatibility function. When the duration b of the second working mode is greater than a second time threshold and the external magnetic field strength is less than a safety threshold, the controller exits the second working mode and deactivates the timing and MRI compatibility function. In this invention, activating the MRI compatibility function includes: activating the current protection function, activating the real-time pulse output monitoring function, and disabling the timed stimulation function. Activating the current protection function can reduce the impact of changing electromagnetic fields on the electrical performance of the IPG during MRI examination. Disabling the timed stimulation function prevents changes in the stimulation state during MRI examination. Activating the real-time pulse output monitoring function immediately shuts down the stimulation output when the pulse output exceeds a preset safety value, and the IPG records abnormal pulse amplitude. Deactivating the MRI compatibility function includes: disabling the current protection function, disabling the real-time pulse output monitoring function, and restoring the timed stimulation function.

[0077] like Figure 5 As shown, after the IPG enters MRI protection mode (second working mode), the specific workflow of S30 and S20a mentioned above includes:

[0078] S31, IPG enters MIR protection mode.

[0079] S32, Enable timing and MRI compatibility functions. Enabling MRI compatibility functions includes: enabling current protection function, enabling real-time monitoring pulse output function, and disabling timed stimulation function.

[0080] S33, determine whether the duration b is greater than the second time threshold. After entering MRI protection mode, the timing unit starts timing, and the recorded duration is the duration b. The duration b can refer to the running time of MRI protection mode or the MRI detection time.

[0081] If so, then execute S34;

[0082] If not, return to step S32. Once the timing and MRI compatibility functions are enabled, they do not need to be enabled again.

[0083] S34, determine whether the external magnetic field strength is less than the safety threshold;

[0084] If so, then execute S35.

[0085] If not, then return to execute S33.

[0086] S35, Exit MIR protection mode, disable timing and MRI compatibility functions. Disabling the MRI compatibility functions includes: disabling current protection function, disabling pulse output real-time monitoring function, and restoring timing stimulation function.

[0087] During IPG operation, the controller also monitors the duration *c* of the external magnetic field detected by the magnetic field sensing unit. When the duration *c* exceeds a third time threshold, the controller flags the magnetic field sensing unit as abnormal. The controller does not enter or exit the second operating mode based on the external magnetic field strength detected by the magnetic field sensing unit. Instead, the IPG enters and exits the second operating mode via instructions from the external programming device. The clock unit includes a first clock module and a second clock module. The first clock module is used for timing the durations *a* and *b*, while the second clock module is used for timing the duration *c*, avoiding timing errors caused by conflicts between different timing functions. In other embodiments, the controller receives a flagging instruction and flags the magnetic field sensing unit as abnormal. The controller does not enter or exit the second operating mode based on the external magnetic field strength detected by the magnetic field sensing unit. The external programming device can send second and third mode instructions to the IPG, enabling the IPG to enter and exit the second operating mode according to these instructions, ensuring the normal activation and deactivation of MRI compatibility functions when the magnetic field sensing unit is abnormal.

[0088] When the IPG is powered on (including the first power-on), the controller can perform a path detection on the magnetic field sensing unit to confirm that the magnetic field sensing unit is not abnormal. When the magnetic field sensing unit is in the path state, if the duration c is less than or equal to the third time threshold, the controller determines that the magnetic field sensing unit is normal.

[0089] like Figure 6 As shown, the workflow of an MRI-compatible neural stimulation system when the magnetic field-sensitive unit malfunctions includes:

[0090] S10b, the external programmable device sends an MRI mode detection command to the IPG, and receives product model information, impedance test information and abnormal information of the magnetic field sensitive unit returned by the IPG based on the MRI mode detection command. If the external programmable device determines that the magnetic field sensitive unit is abnormal, it sends a second mode command to the IPG.

[0091] S20b, IPG enters the second working mode, enabling MRI compatibility mode.

[0092] S30b, the external programmable device sends a third mode command to the IPG.

[0093] S40b, IPG exits the second operating mode.

[0094] Figure 7 This is another schematic diagram of the workflow of an externally programmed device.

[0095] Figure 7 This refers to the specific workflow of S10b. Figure 7 Workflow and Figure 3 The difference in workflow lies in the addition of an external programmed device to determine whether the magnetic field sensitive unit is abnormal. The specific process includes:

[0096] S11b, the external programming device sends an MRI mode detection command to the IPG to exchange MRI compatibility information of the implantable product (IPG), which includes product model information and impedance test information.

[0097] S12b, the external programming device receives implanted product model information (including IPG model, electrode model, extension lead model, electrode adapter information, etc.), impedance test information, and magnetic field sensing unit abnormality information returned by the IPG. Magnetic field sensing unit abnormality information includes: 1. Abnormal, 2. No abnormality, 3. Records of MRI examination duration b exceeding the timeout without exiting and exiting via external command or automatic exit. Abnormal situations include: the duration c of the magnetic field sensing unit detecting the external magnetic field exceeding the third time threshold, and the controller receiving a marker command.

[0098] S13b, determine if there is an impedance abnormality;

[0099] If so, execute S14b and issue an impedance abnormality warning;

[0100] If not, execute S15b. Based on the model information and / or impedance information, the external programmed device determines the MRI examination conditions. Examination conditions include whole body / head, 1.5T / 3.0T, incompatibility, etc., and provides prompts for the determined MRI examination conditions.

[0101] S16b, determine whether the magnetic field sensing unit is abnormal;

[0102] If so, then execute S18b;

[0103] If not, then choose to execute either S17b or S18b.

[0104] S17b, the external programming device sends a first mode command to the IPG, causing the IPG to enter MRI listening mode.

[0105] S18b, the external programming device sends a second mode command to put the IPG into MRI protection mode.

[0106] Figure 8 This is a schematic diagram of another workflow of the MRI protection mode of implantable medical devices in this invention. Figure 8 and Figure 5 The difference lies in the fact that, due to the abnormality of the magnetic field sensitive unit in the second working mode, the IPG cannot exit the second working mode and turn off the MRI compatibility function, which leads to the inability to restore functions such as timed stimulation for a long time, affecting the treatment effect on patients and bringing safety risks.

[0107] The specific process includes:

[0108] S31b, IPG enters MRI protection mode.

[0109] S32b enables the timing and MRI compatibility functions of the first clock module. The MRI compatibility functions include enabling current protection, real-time monitoring of pulse output, and disabling timed stimulation.

[0110] S33b determines whether the duration b is greater than the second time threshold;

[0111] If so, then execute S34b;

[0112] If not, then execute S32b.

[0113] S34b determines whether the duration c is greater than the third time threshold. The duration c is automatically started by the second clock module after it detects the external magnetic field. When the detected external magnetic field disappears for more than t (5min≤t≤60min), the second clock module stops the timing and starts timing again after detecting the external magnetic field again.

[0114] If not, then execute S35b;

[0115] If so, then execute S36b.

[0116] S35, determine whether the external magnetic field strength is less than the safety threshold;

[0117] If so, then execute S36b;

[0118] If not, then execute S33b.

[0119] S36, Exit MRI protection mode, disable the timing and MRI compatibility functions of the first clock module, disable current protection, disable real-time monitoring of pulse output, and restore timed stimulation.

[0120] In this invention, the controller is equipped with a recording unit that can record the most recent ten MRI examination records. Each record includes the start time of the second operating mode, the duration b, any abnormal pulse amplitude, and the exit method of the second operating mode (external command or automatic exit). The external programmable device can read the MRI examination records to facilitate IPG repair based on the abnormal records. If the output is abnormal, it can be determined that there is a problem with the circuit output components.

[0121] In this invention, the first time threshold, the second time threshold, the third time threshold, and the safety threshold can be set by an external programming device, and the specific settings can be made by the user according to the patient's condition.

[0122] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0123] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0124] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0125] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0126] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. An MRI-compatible implantable medical device, characterized in that, Including the controller; The controller is used to receive a first mode instruction and a second mode instruction, so as to enter a first working mode based on the first mode instruction, or to enter a second working mode based on the second mode instruction. In the first working mode, if the controller detects that the duration 'a' of the external magnetic field strength exceeding the safety threshold is greater than the first time threshold, then it switches to the second working mode. In the second working mode, the controller enables timing and MRI compatibility functions. When the duration b of the second working mode is greater than the second time threshold and the external magnetic field strength is less than the safety threshold, the controller exits the second working mode and disables timing and MRI compatibility functions.

2. The MRI-compatible implantable medical device according to claim 1, characterized in that, The controller settings are as follows: A magnetic field sensing unit, wherein the magnetic field sensing unit is used to monitor the strength of the external magnetic field; A clock unit, which is used to time and generate the duration a and duration b.

3. The MRI-compatible implantable medical device according to claim 2, characterized in that, The controller is used to monitor the duration c of the external magnetic field detected by the magnetic field sensing unit. When the duration c is greater than a third time threshold, the controller marks the magnetic field sensing unit as abnormal.

4. The MRI-compatible implantable medical device according to claim 2, characterized in that, The controller is used to receive a marking instruction, and the controller marks the magnetic field sensitive unit as abnormal according to the marking instruction.

5. The MRI-compatible implantable medical device according to claim 3 or 4, characterized in that, The controller is used to receive a third mode instruction. When the magnetic field sensing unit is abnormal, the controller enters the second working mode according to the second mode instruction and exits the second working mode according to the third mode instruction.

6. The MRI-compatible implantable medical device according to claim 1, characterized in that, Enabling the MRI compatibility functions includes: enabling current protection function, enabling real-time monitoring pulse output function, and disabling timed stimulation function; Disabling the MRI-compatible functions includes: disabling the current protection function, disabling the real-time pulse output monitoring function, and restoring the timed stimulation function.

7. The MRI-compatible implantable medical device according to claim 1, characterized in that, The controller is equipped with a recording unit, which is used to record the start time, duration b, and exit method of the second working mode.

8. An MRI-compatible neural stimulation system, characterized in that, Including externally programmed devices and MRI-compatible implantable medical devices as described in any one of claims 1-7; The external programming device is used to send MRI mode control commands to the implantable medical device, the MRI mode control commands including the first mode command and the second mode command.

9. The MRI-compatible neural stimulation system according to claim 8, characterized in that, Before the external programming device sends the MRI mode control command, it includes: Send MRI pattern detection instructions to the implantable medical device; The implantable medical device sends product model information and impedance test information to the external programming device according to the MRI mode detection command.

10. The MRI-compatible neural stimulation system according to claim 9, characterized in that, The external programmed device is pre-loaded with a database that associates product models with magnetic resonance imaging (MRI) conditions; The external programmed device is used to determine whether the impedance test information is abnormal. If so, an error message will be displayed; If not, then match the corresponding magnetic resonance conditions according to the product model.

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