Device and method for accurately measuring muscle magnetic response signal

Abstract

The invention discloses a device for accurately measuring muscle magnetic response signals, which comprises a stimulation module, a data acquisition module and an upper computer, and is characterized in that the stimulation module comprises a constant current square wave generator and an electrode assembly, and the constant current square wave generator comprises a function generator and a voltage-current conversion module; the electrode assembly is a twisted-pair disposable bipolar needle electrode, the input end of the electrode assembly is electrically connected with the output end of the voltage and current conversion module, the data acquisition module comprises a magnetic sensor and an acquisition device, the magnetic sensor is arranged in a magnetic shielding environment, and the output end of the magnetic sensor and the output end of the function generator are electrically connected with the input end of the acquisition device. And the output end of the acquisition device is electrically connected with the upper computer. The invention provides a reliable device, during measurement, through a multi-point data acquisition strategy, stimulation interference is eliminated, an electromagnetic radiation field is inhibited, meanwhile, a control group is set, artifact interference caused by skin electrical conduction and a stimulation current radiation magnetic field is effectively eliminated, and accurate measurement of muscle magnetic response signals is achieved.

Description

Technical Field

[0001] The present invention belongs to the field of biomedical engineering, and in particular relates to a device and method for accurately measuring muscle magnetic response signals. Background Art

[0002] In recent years, due to ecological changes, a faster pace of life, and increased work pressure, the number of diagnoses of musculoskeletal disorders has increased dramatically, even impacting changes in national GDP. Therefore, comprehensive diagnosis, treatment, and management of these disorders are crucial. An article indicates that the overall prevalence of musculoskeletal disorders in indigenous communities in Latin America is 34.5%, accounting for over one-third of the population. Certain conditions, if not diagnosed and treated early, can lead to joint deformities. Musculoskeletal disorders are also increasingly affecting younger people, severely impacting their ability to sustain themselves.

[0003] In clinical diagnosis, electromyography (EMG), as the gold standard, has always been the most accurate test method, but it also has certain shortcomings. Surface electromyography (SEM) is a non-invasive method for detecting diseases, but it cannot diagnose the source of most diseases. Needle electromyography (EMG) is more accurate, but it is an invasive test method that causes pain to patients and is prone to infection. Furthermore, the current status of clinical neuromuscular disease diagnosis is that it is impossible to determine the source of the disease with just one test method, and it relies heavily on the doctor's clinical experience. This makes disease diagnosis difficult, reduces diagnostic efficiency, and increases the time and complexity of patient testing.

[0004] As a completely non-invasive detection method, muscle magnetic detection has the same accuracy as electrical detection in terms of detection. At the same time, magnetic detection is completely non-invasive and can even distinguish the diseased state of muscles at different levels. This undoubtedly provides a new detection method for the diagnosis of clinical diseases. Similar to the stimulation artifacts present in electromyography, there are also artifacts in the muscle magnetic field detection process. The magnetic measurement artifacts mainly come from the magnetic field radiation generated by the electric current. The electromagnetic radiation mainly comes from two aspects: 1) Skin conduction: The skin is an electrical conductor. The electric current may be transmitted in the skin and coupled to the magnetic sensor, causing interference; 2) The radiated magnetic field of the stimulation current: During electrical stimulation, the magnetic field generated by the current passing through the electrodes and wires will interfere with the magnetic sensor and mask the true muscle response. Although these interferences can be reduced through electromagnetic shielding, signal filtering or post-processing algorithms, there are no effective devices and methods in the existing technology that can accurately measure the muscle magnetic response. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to address the deficiencies of the existing technology and provide a device and method for accurately measuring muscle magnetic response signals, thereby providing a reliable device for measuring muscle magnetic response signals. During measurement, a multi-point data acquisition strategy is adopted to eliminate stimulation interference and suppress the electromagnetic radiation field. At the same time, a control group is set up to effectively eliminate artifact interference caused by skin electrical conduction and the magnetic field radiated by the stimulation current, thereby achieving accurate measurement of muscle magnetic response signals.

[0006] The technical solution adopted by the present invention to solve the above technical problems is: a device for accurately measuring muscle magnetic response signals, comprising a stimulation module, a data acquisition module and a host computer, the stimulation module comprising a constant current square wave generator and an electrode assembly, the constant current square wave generator comprising a function generator and a voltage-current conversion module, the electrode assembly being a twisted pair disposable bipolar needle electrode, the input end of the electrode assembly being electrically connected to the output end of the voltage-current conversion module, the data acquisition module comprising a magnetic sensor and an acquisition device, the magnetic sensor being placed in a magnetically shielded environment, the output ends of the magnetic sensor and the function generator being electrically connected to the input end of the acquisition device respectively, the output end of the acquisition device being electrically connected to the host computer, the voltage-current conversion module being used to convert the square wave voltage signal generated by the function generator into a stable current square wave, the electrode assembly being used to apply current square wave stimulation to the limb muscles of the subject being measured and to emit stimulation signals, the magnetic sensor being used to acquire the magnetic response signal at the distal end muscle of the subject being measured along the stimulated nerve pathway, the acquisition device being used to synchronously acquire the stimulation signal and the magnetic response signal, and the host computer being used to display the signal acquired by the acquisition device in real time.

[0007] The device uses twisted-pair disposable bipolar needle electrodes as the electrode assembly. The twisted structure of the twisted pair suppresses magnetic field interference generated by the current, thereby preventing electromagnetic radiation in space. The bipolar needle electrodes also ensure a secure connection with the subject's limb muscles, enabling accurate stimulation signals to be acquired. While applying square wave current to the subject's limb muscles, an acquisition device simultaneously collects the stimulation signal and the magnetic response signal, ensuring temporal consistency.

[0008] Preferably, the magnetic sensor and the object to be measured are both placed in a magnetic shielding cylinder.

[0009] Preferably, the magnetic sensor is a Quspin atomic magnetometer, and its sensitivity is on the order of fT.

[0010] Preferably, the acquisition device is a NI acquisition card.

[0011] A method for accurately measuring muscle magnetic response signals using the above device comprises the following steps:

[0012] (1) Select point A as the stimulation point on the limb muscle of the subject;

[0013] (2) Select point B1 on the distal muscle of the subject below point A, requiring that point B1 and point A are on the same nerve conduction pathway, and place a magnetic sensor below point B1; use the midline of the subject's body as the axis of symmetry, and determine the symmetrical point B2 of point B1 about the axis of symmetry; select point B3 in the space outside the subject's body, and the distance between point B3 and point A is equal to the distance between point B1 and point A;

[0014] (3) Using the stimulation module to apply a current square wave stimulation of a certain frequency and a certain amplitude to point A, while the acquisition device synchronously acquires the stimulation signal and the magnetic response signal; then slowly increasing the stimulation intensity, changing the frequency and amplitude of the current square wave, and continuously stimulating point A until the muscle exhibits mechanical activity and a fluctuation signal appears in the host computer, and the fluctuation signal is recorded and analyzed; changing the frequency and amplitude of the current square wave, performing continuous single stimulation, and recording and analyzing multiple fluctuation signals to obtain the first set of data;

[0015] (4) Move the magnetic sensor below point B2 and repeat step (3) to obtain the second set of data;

[0016] (5) Move the magnetic sensor below point B3 and repeat step (3) to obtain the third set of data;

[0017] (6) Analyze and compare the three sets of data. If the first set of data contains muscle magnetic response signals and mechanical motion signals of the limbs, while the second and third sets of data do not contain muscle magnetic response signals or only contain mechanical motion signals of the limbs, the measurement is considered successful, and the muscle magnetic response signals before the mechanical motion signals appear in the first set of data are used as the measurement results.

[0018] Preferably, the frequency of the current square wave stimulation is 2 Hz, and the amplitude is 10-30 mA.

[0019] Compared with the prior art, the present invention has the following advantages: the device for accurately measuring muscle magnetic response signals of the present invention applies electrical stimulation to specific points of the subject to be measured, and synchronously collects the stimulation signal and the magnetic response signal at the distal end of the muscle of the subject to be measured along the stimulated nerve pathway, which can be used to calculate the nerve conduction velocity and distinguish the characteristic phases of the signal, providing a reliable device for measuring muscle magnetic response signals and a reference for new magnetic detection technology. The method for accurately measuring muscle magnetic response signals of the present invention eliminates stimulation interference and suppresses electromagnetic radiation fields through a multi-point data acquisition strategy, and at the same time sets a control group to effectively eliminate artifact interference caused by skin electrical conduction and the magnetic field radiated by the stimulation current, thereby achieving accurate measurement of muscle magnetic response signals. The subject to be measured of the device and method of the present invention can be any animal, including humans, and is suitable for physiological and pathological studies. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic diagram of a device for accurately measuring muscle magnetic response signals in an embodiment;

[0021] Figure 2 This is a flow chart of measuring the magnetic response signal of guinea pig muscle in the embodiment;

[0022] Figure 3 Schematic diagram (top view) of the positions of the stimulation points and collection points determined in the embodiment;

[0023] Figure 4 Schematic diagram of the placement of the magnetic sensor in the embodiment (left view);

[0024] Figure 5 This is a graph of the collected fluctuation signal after multi-period averaging. DETAILED DESCRIPTION

[0025] The present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

[0026] The device for accurately measuring muscle magnetic response signals of the embodiment, such as Figure 1 The device shown includes a stimulation module, a data acquisition module and a host computer 6. The stimulation module includes a constant current square wave generator and an electrode assembly. The constant current square wave generator includes a function generator 1 and a voltage-current conversion module 2. The electrode assembly is a twisted pair disposable bipolar needle electrode 3. The input end of the electrode assembly is electrically connected to the output end of the voltage-current conversion module 2. The data acquisition module includes a magnetic sensor 4 and an acquisition device 5. In this embodiment, the acquisition device 5 is an NI acquisition card. The magnetic sensor 4 is a Quspin atomic magnetometer with a sensitivity of the order of fT. The output ends of the magnetic sensor 4 and the function generator 1 are respectively electrically connected to the input end of the acquisition device 5. The output end of the acquisition device 5 is electrically connected to the host computer 6. The voltage-current conversion module 2 is used to convert the square wave voltage signal generated by the function generator 1 into a stable current square wave. The electrode assembly is used to pass current square wave stimulation to the limb muscles of the subject and send stimulation signals. The magnetic sensor 4 is used to collect the magnetic response signal at the distal end muscle of the subject along the stimulated nerve pathway. The acquisition device 5 is used to synchronously collect the stimulation signal and the magnetic response signal. The host computer 6 is used to display the signal collected by the acquisition device 5 in real time.

[0027] Take animal experiments as an example. 28-week-old, 590g guinea pigs were used as test subjects. An anesthetic consisting of 20mg / kg of Shutai 50 and 5mg / kg of thiazide was injected into the guinea pigs. After the drug took effect, the guinea pigs were fixed in a supine position on a wooden board about 1cm thick using tape, Velcro, or a fastening rope. The hair on the guinea pigs' lower limbs was cleaned to facilitate manipulation of the lower limb muscle groups. A twisted pair disposable bipolar needle electrode 3 was inserted into the nerve at the proximal end of the guinea pigs' lower limbs. A magnetic sensor 4 was fixed along this nerve below the wooden board at a muscle at the distal end (i.e., below point B1). Note that the magnetic sensor 4 does not contact the muscle skin.

[0028] The magnetic sensor 4 and the guinea pig are placed in the magnetic shielding tube 7, and the device of the embodiment is used to measure the muscle magnetic response signal of the guinea pig, such as Figure 2 As shown, the measurement method includes the following steps:

[0029] (1) Select point A as the stimulation point in the guinea pig's lower limb muscle, such as Figure 3 As shown;

[0030] (2) Select point B1 on the distal end of the guinea pig's muscle below point A. Point B1 and point A must be on the same nerve conduction pathway. Place a magnetic sensor 4 below point B1. Figure 4 As shown, point B1 is used as a collection point, mainly for capturing the magnetic field signal generated by the stimulated muscle; the midline of the guinea pig's body is used as the symmetry axis, and the symmetrical point B2 of point B1 about the symmetry axis is determined. Point B2 is used as a collection point, mainly for recording the interference signal caused by skin electrical conduction. Because it is far away from the stimulated muscle, the muscle magnetic response signal can be ignored; point B3 is selected in the space outside the guinea pig's body, and the distance between point B3 and point A is equal to the distance between point B1 and point A. Point B3 only captures the radiated magnetic field generated by the stimulation current and is not affected by the animal's physiological activities. It is used to exclude the magnetic field radiation of wire electrodes and the like in space;

[0031] (3) Use the stimulation module to apply a current square wave stimulation with a frequency of 2 Hz and an amplitude of 10 to 30 mA to point A. At the same time, the acquisition device 5 synchronously collects the stimulation signal and the magnetic response signal. Then slowly increase the stimulation intensity, change the frequency and amplitude of the current square wave, and continuously stimulate point A until the muscle shows mechanical activity. The following appears in the host computer 6: Figure 5 The fluctuation signal of stage VI is recorded and analyzed, the frequency and amplitude of the current square wave are changed, continuous single stimulation is performed, and the fluctuation signal is recorded and analyzed multiple times to obtain the first set of data;

[0032] (4) Move the magnetic sensor 4 to below point B2 and repeat step (3) to obtain the second set of data;

[0033] (5) Move the magnetic sensor 4 to below point B3 and repeat step (3) to obtain the third set of data;

[0034] (6) Analysis and comparison of the three sets of data revealed that the first set of data contained muscle magnetic response signals and mechanical motion signals of the lower limbs, indicating that the muscles along the nerve pathway produced muscle magnetic response signals and mechanical motion signals of the lower limbs due to nerve stimulation, while the second and third sets of data did not contain muscle magnetic response signals or only contained mechanical motion signals of the lower limbs. The measurement was determined to be successful, and the muscle magnetic response signals before the mechanical motion signals in the first set of data were used as the measurement results.

Claims

1. A device for accurately measuring muscle magnetic response signals, characterized in that: It includes a stimulation module, a data acquisition module and a host computer. The stimulation module includes a constant current square wave generator and an electrode assembly. The constant current square wave generator includes a function generator and a voltage-current conversion module. The electrode assembly is a twisted pair disposable bipolar needle electrode. The input end of the electrode assembly is electrically connected to the output end of the voltage-current conversion module. The data acquisition module includes a magnetic sensor and an acquisition device. The magnetic sensor is placed in a magnetic shielding environment. The output ends of the magnetic sensor and the function generator are respectively electrically connected to the input end of the acquisition device. The output end of the acquisition device is electrically connected to the host computer. The voltage-current conversion module is used to convert the square wave voltage signal generated by the function generator into a stable current square wave. The electrode assembly is used to pass current square wave stimulation to the limb muscles of the subject and send stimulation signals. The magnetic sensor is used to collect the magnetic response signal at the distal end muscle of the subject conducted along the stimulated nerve pathway. The acquisition device is used to synchronously collect the stimulation signal and the magnetic response signal. The host computer is used to display the signal collected by the acquisition device in real time.

2. The device for accurately measuring muscle magnetic response signals according to claim 1, characterized in that: The magnetic sensor and the object to be measured are both placed in the magnetic shielding cylinder.

3. The device for accurately measuring muscle magnetic response signals according to claim 1, characterized in that: The magnetic sensor is a Quspin atomic magnetometer, and its sensitivity is on the order of fT.

4. The device for accurately measuring muscle magnetic response signals according to claim 1, characterized in that: The acquisition device is a NI acquisition card.

5. A method for accurately measuring muscle magnetic response signals using the device according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) Select point A as the stimulation point on the limb muscle of the subject; (2) Select point B1 on the distal muscle of the subject below point A, requiring that point B1 and point A are on the same nerve conduction pathway, and place a magnetic sensor below point B1; use the midline of the subject's body as the axis of symmetry, and determine the symmetrical point B2 of point B1 about the axis of symmetry; select point B3 in the space outside the subject's body, and the distance between point B3 and point A is equal to the distance between point B1 and point A; (3) Using the stimulation module to apply a current square wave stimulation of a certain frequency and a certain amplitude to point A, while the acquisition device synchronously acquires the stimulation signal and the magnetic response signal; then slowly increasing the stimulation intensity, changing the frequency and amplitude of the current square wave, and continuously stimulating point A until the muscle exhibits mechanical activity and a fluctuation signal appears in the host computer, and the fluctuation signal is recorded and analyzed; changing the frequency and amplitude of the current square wave, performing continuous single stimulation, and recording and analyzing multiple fluctuation signals to obtain the first set of data; (4) Move the magnetic sensor below point B2 and repeat step (3) to obtain the second set of data; (5) Move the magnetic sensor below point B3 and repeat step (3) to obtain the third set of data; (6) Analyze and compare the three sets of data. If the first set of data contains muscle magnetic response signals and mechanical motion signals of the limbs, while the second and third sets of data do not contain muscle magnetic response signals or only contain mechanical motion signals of the limbs, the measurement is considered successful, and the muscle magnetic response signals before the mechanical motion signals appear in the first set of data are used as the measurement results.

6. The method for accurately measuring muscle magnetic response signals according to claim 5, characterized in that: The frequency of the current square wave stimulation is 2 Hz, and the amplitude is 10-30 mA.

Images