A trigger switching device for magnetic resonance current density imaging

Abstract

The present invention discloses a trigger switching device for magnetic resonance current density imaging, which is composed of an optical fiber conversion module, a main control module, a communication module, a current conversion module and a current output module. The present invention is reasonably designed, and by receiving an optical signal and converting it into an electrical signal, triggering and changing the direction of the stimulation current and the duty cycle of the current signal, the accuracy, practicality and reliability of magnetic resonance current density imaging are improved; the trigger switching device includes five parts: an optical fiber conversion module, a main control module, a communication module, a current conversion module and a current output module; the current conversion module changes the connection mode between the input channel and the output channel according to the instruction, and switches between three modes: short circuit, forward output and reverse output. It is a trigger switching device that can switch the direction and duty cycle of the stimulation current in conjunction with magnetic resonance current density imaging, and solves the problem that magnetic resonance current density imaging is difficult to be linked with the current generating device in real time.

Description

Technical Field

[0001] The present invention belongs to the technical field of scientific instruments, and relates to a trigger switching device capable of switching the direction and duty cycle of stimulation current in conjunction with magnetic resonance current density imaging, and in particular to a trigger switching device for magnetic resonance current density imaging. Background Art

[0002] Magnetic resonance current density imaging (MRCDI) is a technology that accurately images the distribution of current in the brain. It obtains information on current and conductivity by combining weak time-varying current input from electrodes on the scalp surface with magnetic resonance imaging (MRI). It has the advantages of being non-invasive and highly accurate, and has important applications in neuroscience.

[0003] According to the principle of magnetic resonance imaging, current is injected into the conductor boundary to form a current density distribution inside the conductor. The current density distribution excites the formation of a magnetic flux density distribution. The component of the excitation magnetic field parallel to the main magnetic field of the magnetic resonance device will affect the phase of the magnetic resonance echo signal, accumulating to form a phase change. By detecting the change in the phase of the magnetic resonance echo signal, the current density distribution in the imaging target is obtained by reverse deduction. In order to improve the signal-to-noise ratio of imaging, it is required to convert the direction of the input current or stop the input current while the magnetic resonance device emits a specific radio frequency (RF) signal to increase the accumulated phase change and improve the imaging quality under the same noise interference.

[0004] Existing current generating devices that can be used for magnetic resonance imaging are difficult to realize the function of being triggered by the output signal of the magnetic resonance imaging device and changing the current direction or stopping the output current. The current parameters including the current direction, current intensity, output time, etc. are all set before the imaging starts and cannot be switched during the imaging process. The function of adjusting the duty cycle is also difficult to realize. Moreover, the existing equipment cannot recognize the trigger light signal of the magnetic resonance imaging device, and the input current is difficult to cooperate with the magnetic resonance imaging. Therefore, there is a problem that magnetic resonance current density imaging is difficult to be linked with the current generating device in real time.

[0005] Therefore, in magnetic resonance current density imaging, a trigger switching device is needed to change the direction of the stimulation current and the duty cycle of the current signal in coordination with magnetic resonance current density imaging. This is of great significance to the accuracy, practicality and reliability of magnetic resonance current density imaging. Summary of the invention

[0006] The purpose of the present invention is to provide a trigger switching device for magnetic resonance current density imaging, which is a trigger switching device that can switch the stimulation current direction and duty cycle in conjunction with magnetic resonance current density imaging, thereby solving the problem that magnetic resonance current density imaging is difficult to be linked with a current generating device in real time.

[0007] The technical means adopted by the present invention to solve the problem is as follows: the device comprises five parts: an optical fiber conversion module, a main control module, a communication module, a current conversion module and a current output module.

[0008] The optical fiber conversion module is connected to the main control module, the communication module is connected to the main control module, the current conversion module is connected to the main control module, and the current output module is connected to the current conversion module.

[0009] The optical fiber conversion module is used for converting optical signals into electrical signals, receiving signals transmitted from the optical fiber by the magnetic resonance current density imaging device, and converting them into TTL levels for subsequent data transmission and processing.

[0010] The main control module is used to trigger the coordinated control and data processing of the switching device, and can be implemented by a processor such as a single-chip microcomputer or FPGA.

[0011] The communication module is used to receive control commands from external application software, and can use wired or wireless communication methods such as USB, Bluetooth, WiFi, etc.

[0012] The current output module is used for outputting current and can be connected to stimulation electrodes through electrode lead wires and placed on the surface of the human body.

[0013] The current conversion module is used to change the stimulation current direction and the current signal duty cycle according to the instruction. The current conversion module switches between the short circuit, forward output and reverse output modes by changing the connection mode between the input channel and the output channel, and can be implemented by selecting a multi-channel analog switch.

[0014] Compared with the prior art, the present invention has the following advantages: (1) it can receive the trigger light signal of the magnetic resonance current density imaging device and be triggered to convert the current direction; (2) the duty cycle of the output current signal can be set through the application software to output a current signal with a customized duty cycle; (3) the present invention is reasonably designed and has programmable functions, which can trigger the conversion and output of multiple modal signals, making the accuracy, practicality and reliability of magnetic resonance current density imaging higher, which is of great significance for the in-depth study of scientific problems. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic block diagram of the structure of the trigger switching device of the present invention.

[0016] Figure 2This is a structural block diagram of an implementation scheme of the current conversion module of the present invention.

[0017] Figure 3 It is a flow chart of the use process of the present invention. DETAILED DESCRIPTION

[0018] The present invention is further described in conjunction with the accompanying drawings and embodiments.

[0019] Example 1

[0020] See also Figure 1 , which is a schematic block diagram of the structure of a trigger switching device for magnetic resonance current density imaging of the present invention, mainly including five parts including an optical fiber conversion module 1, a main control module 2, a communication module 3, a current conversion module 4 and a current output module 5. The figure shows the connection relationship between the modules. The optical fiber conversion module 1 is connected to the main control module 2, the communication module 3 is connected to the main control module 2, the current conversion module 4 is connected to the main control module 2, and the current output module 5 is connected to the current conversion module 4. The trigger light signal is input into the optical fiber conversion module 1, the input current is input into the current conversion module 4, and the output current is output from the current output module 5.

[0021] Example 2

[0022] See also Figure 2 , which is a structural block diagram of an implementation method of the current conversion module of the present invention. A multi-way analog switch is selected to realize the function of changing the stimulation current direction and the current signal duty cycle. Pins 41 and 42 are respectively connected to the positive and negative direction currents input from the current generating device. Pins 43 and 44 are respectively used as stimulation channel 1 and stimulation channel 2, connected to the current output module 5. By changing the internal connection method, three modes of short circuit, forward output, and reverse output are realized.

[0023] In the short-circuit mode, pin 41 and pin 42 are both connected to position 45, and there is no output current in stimulation channel 1 and stimulation channel 2; in the forward output mode, pin 41 is connected to pin 43, pin 42 is connected to pin 44, stimulation channel 1 outputs a forward current, and stimulation channel 2 outputs a negative current, that is, an inflow current; in the reverse output mode, pin 41 is connected to pin 44, pin 42 is connected to pin 43, stimulation channel 1 outputs a negative current, that is, an inflow current, and stimulation channel 2 outputs a forward current. The current conversion module 4 receives instructions from the main control module 2, switches between the three modes of short circuit, forward output, and reverse output, and realizes the function of changing the direction of the stimulation current and the duty cycle of the current signal.

[0024] The working process of the device of the present invention is described as follows: The present invention is a trigger switching device for magnetic resonance current density imaging, which needs to be connected to a magnetic resonance current density imaging device and a current generating device for use. Before the module is operated, the optical fiber conversion module 1 is first connected to the magnetic resonance current density imaging device, the current conversion module 4 is connected to the external current generating device, and the current output module 5 is connected to the imaging target. Figure 3 As shown, the experimental workflow of the device of the present invention is given. First, the module is connected and powered on, and the parameters of the trigger switching device are set through the wired or wireless connection of the external application software and the communication module, wherein the parameters mainly include the trigger mode, duty cycle, current signal mode, etc.

[0025] After the system starts running, the main control module 2 determines whether to start outputting current according to the set current signal mode. If the current is not output, the current conversion module 4 maintains the short-circuit mode and waits for the trigger signal. If the current starts to be output, the current conversion module 4 enters the forward output or reverse output mode according to the setting. The main control module 2 determines whether the optical fiber conversion module 1 receives the signal for switching the current direction. If the signal is received, the current conversion module 4 is controlled to change the mode and switch the current direction. If it is not received, it remains unchanged. Next, the main control module 2 determines whether the signal for suspending the output of the current is received. If the signal is received, the current conversion module 4 enters the short-circuit mode, suspends the output of the current, and waits for the signal to start outputting the current. If the signal is not received, the current continues to be output, and the main control module 2 repeatedly enters the cycle of judging whether the optical fiber conversion module 1 receives the signal for switching the current direction. In this process, the main control module 2 can send instructions to the current conversion module 4 at a specific time according to the duty cycle set in advance, combined with the signal received by the optical fiber conversion module 1, to change the mode of the current conversion module 4 and realize the function of adjusting the duty cycle.

Claims

1. A trigger switching device for magnetic resonance current density imaging, characterized in that: The optical fiber conversion module (1) is connected to the main control module (2), the communication module (3), the current conversion module (4) is connected to the main control module (2), the communication module (3) is connected to the main control module (2), the current conversion module (4) is connected to the main control module (2), and the current output module (5) is connected to the current conversion module (4); The optical fiber conversion module (1) is used for converting optical signals into electrical signals, receiving signals transmitted from the optical fiber by the magnetic resonance current density imaging device, and converting them into TTL levels for subsequent data transmission and processing; The current conversion module (4) is used to change the stimulation current direction and the current signal duty cycle according to the instruction. The current conversion module switches between the three modes of short circuit, forward output and reverse output by changing the connection mode between the input channel and the output channel, and a multi-channel analog switch is selected for implementation.

2. A trigger switching device for magnetic resonance current density imaging according to claim 1, characterized in that: The main control module (2) is used for triggering the coordinated control and data processing of the switching device, and is implemented by a single-chip microcomputer or an FPGA processor.

3. A trigger switching device for magnetic resonance current density imaging according to claim 1, characterized in that: The communication module (3) is used to receive control commands from external application software, using USB, Bluetooth, WiFi wired or wireless communication methods.

4. A trigger switching device for magnetic resonance current density imaging according to claim 1, characterized in that: The current output module (5) is used for outputting current, is connected to stimulation electrodes via electrode lead wires, and is placed on the surface of the human body.

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