Transcranial magnetic acoustic stimulation and stimulation current monitoring device and method

Abstract

The present invention relates to a transcranial magnetoacoustic stimulation and stimulation current monitoring device and method. The device comprises: a pulse excitation source, an ultrasonic transducer, a magnet, a magnetic field sensor array, and a control unit. The pulse excitation source emits microsecond pulse excitations to stimulate the ultrasonic transducer to generate ultrasonic waves. The ultrasonic transducer generates focused ultrasonic waves that act on the stimulation area and, under the action of the magnet, generate a stimulation current. The magnetic field sensor array is arranged around the stimulated brain to detect the pulsed magnetic field signal stimulated by the stimulation current. The transcranial magnetoacoustic stimulation current monitoring method comprises: a first step of calculating a coefficient matrix based on a pre-designed stimulation target area; a second step of simultaneously performing magnetoacoustic stimulation on the brain and detecting the pulsed magnetic field signal stimulated by the stimulation current via the magnetic field sensor array arranged around the stimulated brain; and a third step of calculating the current density of the magnetoacoustic stimulation current. The above-mentioned device and method of the present invention provide effective tools and means for optimizing magnetoacoustic brain stimulation systems and analyzing stimulation mechanisms.

Description

Technical Field

[0001] The present invention relates to the field of transcranial stimulation, and in particular to a transcranial magnetoacoustic stimulation and stimulation current monitoring device and method. Background Art

[0002] Brain stimulation is an important means of treating mental or neurological diseases. Deep brain stimulation technology has high surgical risks, while transcranial magnetic stimulation and transcranial electrical stimulation do not require surgery, but are mainly used for superficial brain stimulation. Ultrasonic stimulation is a non-destructive deep brain stimulation technology, but the mechanism of stimulation is unknown. Magnetoacoustic brain stimulation is a deep brain stimulation technology that couples ultrasound and electromagnetic fields. It uses ultrasound to act on brain tissue, forming a motional current under the action of a magnetic field. The mechanism of action is similar to that of electrical stimulation and magnetic stimulation. The intensity and distribution of the stimulation current directly affect the effect of magnetoacoustic stimulation. In the prior art, the electrical stimulation current monitoring device and monitoring method combined with ultrasound and magnetoacoustics (CN201810509097.7) uses back-projection reconstruction to obtain a sound source image as a current monitoring method, which is aimed at traditional electrical stimulation methods, and cannot obtain the distribution of the stimulation current. Traditional magnetic measurement technology is mainly used in fields such as brain magnetism or electrical impedance imaging, and is aimed at low-frequency electromagnetic fields, so it is only suitable for low-frequency current monitoring. Magnetoacoustic brain stimulation uses microsecond pulsed excitation signals to stimulate ultrasound, which in turn generates a stimulation current. This stimulation current is a pulsed signal with a frequency ranging from several hundred kHz to 1 MHz. Currently, there is a lack of effective technology to monitor the stimulation current during magnetoacoustic brain stimulation, making it difficult to effectively assess the intensity and distribution of the stimulation current. Summary of the Invention

[0003] The purpose of the present invention is to provide a transcranial magnetoacoustic stimulation and stimulation current monitoring device and method, which can monitor the pulse stimulation current stimulated during magnetoacoustic brain stimulation.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] A transcranial magnetic acoustic stimulation and stimulation current monitoring device, comprising:

[0006] A pulse excitation source, an ultrasonic transducer, a first magnet, a second magnet, a magnetic field sensor array, and a control unit;

[0007] The pulse excitation source is used to emit a microsecond pulse excitation signal and excite the ultrasonic transducer to generate ultrasonic waves, and the ultrasonic transducer generates focused ultrasonic waves to act on the stimulation area;

[0008] The first magnet and the second magnet are used to generate a magnetic field, which works together with the ultrasound to generate a stimulation current;

[0009] The magnetic field sensor array is used to detect the pulsed magnetic field signal excited by the magnetoacoustic stimulation current;

[0010] The control unit is used to synchronize the pulse excitation source and the magnetic field sensor. The control unit is also used to process the pulse magnetic field signal and calculate the current density of the stimulation current.

[0011] Optionally, a single magnetic field sensor in the magnetic field sensor array includes: a three-component detection coil, a preamplifier, an integrator, a bandpass filter and a postamplifier; the three-component detection coil, the preamplifier, the integrator, the bandpass filter and the postamplifier are connected in sequence.

[0012] Based on the above-mentioned device in the present invention, the present invention further provides a transcranial magnetic acoustic stimulation and stimulation current monitoring method, which is applied to the above-mentioned device and includes:

[0013] Calculate the coefficient matrix based on the stimulation target area;

[0014] During brain stimulation, the pulsed magnetic field signal generated by the stimulation current is synchronously detected by an array of magnetic field sensors deployed around the brain;

[0015] According to the set calculation time step, the current density of the stimulation current at all calculation moments is determined based on the coefficient matrix and the pulsed magnetic field signal.

[0016] Optionally, the current density of the stimulation current at each calculation moment is determined based on the coefficient matrix and the pulsed magnetic field signal using the following formula:

[0017] b k =AJ k

[0018] Among them, A represents the coefficient matrix, b k represents the pulse magnetic field signal vector at the kth calculation moment, J k Represents the current density vector at the kth calculation moment.

[0019] Optionally, the coefficient matrix is ​​independent of the calculation time and is expressed as

[0020]

[0021] Among them, (x′ j , y′ j , z′ j ) represents the spatial coordinate of the jth stimulation current grid, j = 1, ..., N, N represents the number of grids; (x i ,y i , z i ) represents the spatial position of the i-th magnetic field sensor, i=1,…,M, where M represents the number of magnetic field sensors; d ijrepresents the distance from the i-th magnetic field sensor to the j-th stimulation current grid, β represents the coefficient of dispersion, which is β=1 / (αΔ 3 ), Δ represents the spatial discrete step length, and α represents the characteristic constant coefficient.

[0022] Optionally, the characteristic constant coefficient of the detection coil is expressed as follows:

[0023] Where α represents the characteristic constant of the detection coil, μ0 represents the magnetic permeability of vacuum, N represents the number of turns of the detection coil, and S represents the area of ​​a single-turn detection coil.

[0024] Optionally, the pulsed magnetic field signal vector and the current density vector are specifically expressed as follows:

[0025]

[0026] in, b iy 、b iz They represent the pulse magnetic field signals detected by the detection coils of the three directions x, y, and z of the i-th magnetic field sensor at the k-th calculation moment, respectively, i = 1, ..., M; represents the current density components in the x, y, and z directions of the j-th stimulation current grid at the k-th calculation moment, j = 1, ..., N.

[0027] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0028] The present invention provides a transcranial magnetoacoustic stimulation and stimulation current monitoring device and method, which are equipped with a pulse excitation source, an ultrasonic transducer, a first magnet, a second magnet, a magnetic field sensor array and a control unit. The additional magnetic field sensor array is conducive to evaluating the magnetoacoustic stimulation effect and provides a basis for the design and optimization of the sound pressure, magnetic field and the entire stimulation system of the magnetoacoustic stimulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0030] Figure 1 This is a schematic structural diagram of a transcranial magnetic acoustic stimulation and stimulation current monitoring device according to an embodiment of the present invention;

[0031] Figure 2 This is a flow chart of a transcranial magnetic acoustic stimulation and stimulation current monitoring method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0033] The purpose of the present invention is to provide a transcranial magnetoacoustic stimulation and stimulation current monitoring device and method to directly monitor the stimulation current of magnetoacoustic brain stimulation and effectively evaluate the stimulation current intensity and distribution.

[0034] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] Figure 1 FIG. 1 is a schematic structural diagram of a transcranial magnetic acoustic stimulation and stimulation current monitoring device according to an embodiment of the present invention. Figure 1 As shown, the device includes:

[0036] Pulse excitation source 1, ultrasonic transducer 2, first magnet 3, second magnet 4, magnetic field sensor array 5 and control unit 6;

[0037] The pulse excitation source 1 and the ultrasonic transducer 2 generate ultrasonic waves, which act on the stimulation area and generate stimulation current under the action of the first magnet 3 and the second magnet 4; the magnetic field sensor array 5 is arranged around the stimulated brain 7 to detect the pulse magnetic field signal excited by the stimulation current.

[0038] The pulse excitation source 1 emits a microsecond pulse excitation signal to excite the ultrasonic transducer 2 to generate ultrasonic waves; the ultrasonic transducer 2 generates focused ultrasonic waves to act on the stimulation area.

[0039] The magnetic field sensor array 5 detects the pulsed magnetic field signal excited by the magnetoacoustic stimulation current; a single magnetic field sensor includes a three-component detection coil, a preamplifier, an integrator, a bandpass filter and a postamplifier; the detection coils are orthogonal to each other and can simultaneously measure pulsed magnetic field signals in three directions.

[0040] The control unit 6 synchronizes the pulse excitation source 1 and the magnetic field sensor array 5 and is responsible for processing the pulse magnetic field signal and calculating the current density of the stimulation current.

[0041] like Figure 2 As shown, the transcranial magnetic acoustic stimulation and stimulation current monitoring method includes:

[0042] S1: Calculate the coefficient matrix based on the stimulation target area;

[0043] Magnetoacoustic stimulation uses ultrasonic waves to make particles in the stimulated area move. The moving particles are subjected to the Lorentz force under the action of the magnetic field, forming a motional current source, thereby forming a stimulation current near the stimulated area with a current density of

[0044]

[0045] Where σ is the tissue conductivity, v is the vibration velocity of the particle under ultrasound, is the magnetic induction intensity, u is the electrical position, is the current density of the stimulation current. This stimulation current stimulates the brain tissue while also stimulating an electromagnetic field in the space around the brain.

[0046] The magnetic field sensor array deployed around the brain detects the pulsed magnetic field signal formed by the stimulation current. The pulsed magnetic field signal detected by each component coil is:

[0047]

[0048] in, It represents the spatial location of the stimulation current generated by the brain tissue, and its three components are (x′, y′, z′); Represents the spatial position of the detection coil, with three components (x, y, z); Respectively represent the pulse magnetic field signals detected by the detection coils in the x, y, and z directions, Represents the three components of the current density of the stimulation current, the volume area Ω represents the distribution area of ​​the stimulation current, and α represents the characteristic constant coefficient of the detection coil, which is obtained through calibration and its theoretical value is

[0049]

[0050] Where μ0 represents the magnetic permeability of vacuum, which is 4π×10 -7 H / m, N represents the number of turns of the detection coil, and S represents the area of ​​a single turn of the detection coil.

[0051] Assume that there are M magnetic field sensors, that is, 3M detection coils, and the detection coils are numbered i = 1, ..., 3M; the number of grids for the stimulation current distribution area is N, and the calculation moments are numbered k = 1, ..., K, with a total of K calculation moments. At the kth calculation moment, equation (2) can be rewritten as a discrete matrix form:

[0052] AJ k =b k (4)

[0053] Where A represents the coefficient matrix, with 3M rows and 3N columns; Jk represents the current density vector at the kth calculation moment, which has 3N elements; b represents the pulsed magnetic field signal vector at the kth calculation moment, which has a total of 3M elements. The specific element distribution of equation (4) is as follows:

[0054]

[0055] Among them, d ij , i = 1, ..., M; j = 1, ..., N represents the distance from the i-th magnetic field sensor to the j-th stimulation current grid, β represents the coefficient of dispersion, which is β=1 / (αΔ 3 ), Δ represents the discrete step length of space; b iy 、b iz They represent the pulse magnetic field signals detected by the detection coils of the three directions x, y, and z of the i-th magnetic field sensor at the k-th calculation moment respectively; Represents the current density components in the x, y, and z directions of the j-th stimulation current grid at the k-th calculation moment.

[0056] The coefficient matrix A is only related to the spatial position of the detection coil and the stimulation current, the integral discretization method and the characteristic constant coefficient α, and does not change with time. It can be calculated and stored in advance according to the stimulation target area to improve calculation efficiency.

[0057] Specifically, the coefficient matrix A can be calculated in blocks, with three M-row, N-column zero submatrices on the diagonal. Only the three M-row, N-column submatrices in the upper left corner need to be calculated. The three submatrices in the lower right corner are antisymmetric to the three submatrices in the upper left corner, that is, their values ​​are equal, and they only differ by a negative sign.

[0058] It is even possible to calculate the pseudo-inverse of the coefficient matrix in advance, thereby reducing the time spent on solving equations during the stimulation process. Only simple multiplication of matrices and vectors needs to be calculated, further accelerating the speed of calculating current density and achieving real-time monitoring.

[0059] S2: During brain stimulation, a magnetic field sensor array deployed around the brain synchronously detects the pulsed magnetic field signal generated by the stimulation current. Its essence is the time integral of the induced electromotive force.

[0060] S3: Solve equation (4) according to the set calculation time step to obtain the current density of the stimulation current at each calculation moment, thereby achieving the goal of monitoring the magnetoacoustic stimulation current.

[0061] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0062] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A transcranial magnetic acoustic stimulation and stimulation current monitoring device, characterized in that: The device comprises: A pulse excitation source, an ultrasonic transducer, a first magnet, a second magnet, a magnetic field sensor array, and a control unit; The pulse excitation source is used to emit a microsecond pulse excitation signal and excite the ultrasonic transducer to generate ultrasonic waves, and the ultrasonic transducer generates focused ultrasonic waves to act on the stimulation area; The first magnet and the second magnet are used to generate a magnetic field, which works together with the ultrasound to generate a stimulation current; The magnetic field sensor array is used to detect the pulsed magnetic field signal excited by the magnetoacoustic stimulation current; The control unit is used to synchronize the pulse excitation source and the magnetic field sensor array. The control unit is also used to process the pulse magnetic field signal and calculate the current density of the stimulation current; the current density of the stimulation current is: Where σ is the tissue conductivity, v is the vibration velocity of the particle under ultrasound, is the magnetic induction intensity, u is the electrical position, is the current density of the stimulation current. While stimulating brain tissue, the stimulation current also excites an electromagnetic field in the space around the brain. The pulsed magnetic field signal generated by the stimulation current is detected by the magnetic field sensor array. The pulsed magnetic field signal detected by each component coil is: in, It represents the spatial location of the stimulation current generated by the brain tissue, and its three components are (x′, y′, z′); Represents the spatial position of the detection coil, with three components (x, y, z); Respectively represent the pulse magnetic field signals detected by the detection coils in the x, y, and z directions, The three components of the current density of the stimulation current are represented by Ω, the volume area represents the distribution area of ​​the stimulation current, and α represents the characteristic constant coefficient of the detection coil, which is obtained through calibration. Its theoretical value is: Where μ0 represents the magnetic permeability of vacuum, which is 4π×10 -7 H / m, n represents the number of turns of the detection coil, and S represents the area of ​​a single turn detection coil; There are M magnetic field sensors in total, the number of grids for the stimulation current distribution area is N, the calculation moments are numbered k=1,...,K, and there are K calculation moments in total. At the kth calculation moment, the expression of the pulse magnetic field signal detected by each component coil is rewritten in discrete matrix form: English k =b k ; Where A represents the coefficient matrix, which has 3M rows and 3N columns; J K represents the current density vector at the kth calculation moment, with a total of 3N elements; b k Represents the pulse magnetic field signal vector at the kth calculation moment, with a total of 3M elements; The coefficient matrix A is only related to the spatial position of the detection coil and the stimulation current, the integral discretization method and the characteristic constant coefficient α, and is expressed as: Among them, (x′ j , y′ j , z′ j ) represents the spatial coordinate of the jth stimulation current grid, j = 1, ..., N, N represents the number of grids; (x i ,y i , z i ) represents the spatial position of the i-th magnetic field sensor, i=1,…,M, where M represents the number of magnetic field sensors; d ij represents the distance from the i-th magnetic field sensor to the j-th stimulation current grid β represents the coefficient of dispersion, which is β=1 / (αΔ 3 ), Δ represents the discrete step length of space; Specifically, the coefficient matrix A is arranged according to the coordinate components shown to form a sparse matrix, with three zero submatrices of M rows and N columns on the secondary diagonal; only the three M-row and N-column submatrices in the upper left corner need to be calculated, and the three submatrices in the lower right corner are antisymmetric to the three submatrices in the upper left corner, that is, their values ​​are equal, differing only by a negative sign; by calculating and solving the pseudo-inverse of the block matrix in advance and storing it, the time spent on solving the equations during the stimulation process is reduced, and only simple matrix and vector multiplication needs to be calculated, which further accelerates the speed of calculating the current density and realizes real-time monitoring of the stimulation current; The pulsed magnetic field signal vector and current density vector correspond to the coefficient matrix, and the specific expressions are as follows: in, They represent the pulse magnetic field signals detected by the detection coils of the three directions x, y, and z of the i-th magnetic field sensor at the k-th calculation moment, respectively, i = 1, ..., M; represents the current density components in the x, y, and z directions of the j-th stimulation current grid at the k-th calculation moment, j = 1, ..., N.

2. The transcranial magnetic acoustic stimulation and stimulation current monitoring device according to claim 1, characterized in that: A single magnetic field sensor in the magnetic field sensor array includes: a three-component detection coil, a preamplifier, an integrator, a bandpass filter, and a postamplifier; the three-component detection coil, the preamplifier, the integrator, the bandpass filter, and the postamplifier are connected in sequence.

3. A transcranial magnetic acoustic stimulation and stimulation current monitoring method, characterized in that: The monitoring method is applied to the device according to any one of claims 1 to 2, and the method includes: Calculate the coefficient matrix based on the stimulation target area; During brain stimulation, the pulsed magnetic field signal generated by the stimulation current is synchronously detected by an array of magnetic field sensors deployed around the brain; According to the set calculation time step, the current density of the stimulation current at all calculation moments is determined based on the coefficient matrix and the pulsed magnetic field signal; the current density of the stimulation current is: Where σ is the tissue conductivity, v is the vibration velocity of the particle under ultrasound, is the magnetic induction intensity, u is the electrical position, is the current density of the stimulation current. While stimulating brain tissue, the stimulation current also excites an electromagnetic field in the space around the brain. The pulsed magnetic field signal generated by the stimulation current is detected by the magnetic field sensor array. The pulsed magnetic field signal detected by each component coil is: in, It represents the spatial location of the stimulation current generated by the brain tissue, and its three components are (x′, y′, z′); Represents the spatial position of the detection coil, with three components (x, y, z); Respectively represent the pulse magnetic field signals detected by the detection coils in the x, y, and z directions, The three components of the current density of the stimulation current are represented by Ω, the volume area represents the distribution area of ​​the stimulation current, and α represents the characteristic constant coefficient of the detection coil, which is obtained through calibration. Its theoretical value is: Where μ0 represents the magnetic permeability of vacuum, which is 4π×10 -7 H / m, n represents the number of turns of the detection coil, and S represents the area of ​​a single turn detection coil; There are M magnetic field sensors in total, the number of grids for the stimulation current distribution area is N, the calculation moments are numbered k=1,…,K, and there are K calculation moments in total. At the kth calculation moment, the expression of the pulse magnetic field signal detected by each component coil is rewritten in discrete matrix form: English k =b k ; Where A represents the coefficient matrix, which has 3M rows and 3N columns; J K represents the current density vector at the kth calculation moment, with a total of 3N elements; b k Represents the pulse magnetic field signal vector at the kth calculation moment, with a total of 3M elements; The coefficient matrix A is only related to the spatial position of the detection coil and the stimulation current, the integral discretization method and the characteristic constant coefficient α. The coefficient matrix is ​​independent of the calculation time and is expressed as: Among them, (x′ j , y′ j , z′ j ) represents the spatial coordinate of the jth stimulation current grid, j = 1, ..., N, N represents the number of grids; (x i ,y i , z i ) represents the spatial position of the i-th magnetic field sensor, i=1,…,M, where M represents the number of magnetic field sensors; d ij represents the distance from the i-th magnetic field sensor to the j-th stimulation current grid β represents the coefficient of dispersion, which is β=1 / (αΔ 3 ), Δ represents the discrete step length of space. Specifically, the coefficient matrix A is arranged according to the coordinate components shown to form a sparse matrix, with three zero submatrices of M rows and N columns on the secondary diagonal; only the three M-row and N-column submatrices in the upper left corner need to be calculated, and the three submatrices in the lower right corner are antisymmetric to the three submatrices in the upper left corner, that is, their values ​​are equal, differing only by a negative sign; by calculating and solving the pseudo-inverse of the block matrix in advance and storing it, the time spent on solving the equations during the stimulation process is reduced, and only simple matrix and vector multiplication needs to be calculated, which further accelerates the speed of calculating the current density and realizes real-time monitoring of the stimulation current; The pulse magnetic field signal vector and current density vector correspond to the coefficient matrix, and the specific expressions are as follows: in, They represent the pulse magnetic field signals detected by the detection coils of the three directions x, y, and z of the i-th magnetic field sensor at the k-th calculation moment, respectively, i = 1, ..., M; represents the current density components in the x, y, and z directions of the j-th stimulation current grid at the k-th calculation moment, j = 1, ..., N.

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