A transcranial magneto-acoustic coupling stimulation method and device

Abstract

The present invention relates to a transcranial magnetoacoustic coupling stimulation method and apparatus. The stimulation apparatus includes: an ultrasonic focusing module, a stimulation object fixing module, and a stimulation current detection module; the ultrasonic focusing module is used to achieve focused stimulation; the stimulation object fixing module is used to fix the stimulation object; the stimulation current detection module is used to achieve real-time monitoring of the current density at the target point of a specific brain region of the stimulation object. The above-mentioned apparatus in the present invention can achieve non-invasive electrical stimulation of the brain with high spatial resolution.

Description

Technical Field

[0001] The present invention relates to the field of transcranial stimulation, and particularly to a transcranial magnetoacoustic coupling stimulation method and apparatus. Background Art

[0002] Transcranial magnetoacoustic coupling neuromodulation technology is a novel brain stimulation technology, that is, it uses the coupling effect of magnetic field and ultrasonic wave to generate an electric field, and then regulates nerve activities. Different from the simple electro, magnetic, optical, and acoustic regulation means, transcranial magnetoacoustic coupling neuromodulation is a composite nerve stimulation technology that combines sound field and magnetic field, and realizes precise electrical regulation of nerve tissue by virtue of the high penetration depth and high focusing property of low-intensity focused ultrasound on the brain. Common transcranial nerve stimulations such as transcranial direct current stimulation and transcranial magnetic stimulation currently cannot achieve millimeter-level high-resolution focusing and it is difficult to achieve stimulation of deep brain regions. Transcranial magnetoacoustic coupling stimulation has the advantages of both stimulation focusing and stimulation depth. Since the electric field strength of the focused electric field in transcranial magnetoacoustic coupling stimulation is jointly determined by the ultrasonic sound pressure at the focal point and the magnetic induction intensity of the static magnetic field, the magnetoacoustic coupling focused magnetic field strength in transcranial magnetoacoustic technology is relatively low. Summary of the Invention

[0003] The purpose of the present invention is to provide a non-invasive deep brain precise stimulation method and apparatus for transcranial magnetoacoustic coupling, which is used to achieve non-invasive electrical stimulation of the brain with high spatial resolution.

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

[0005] A transcranial magnetoacoustic coupling stimulation method, the method comprising:

[0006] Detecting an induced electromotive force;

[0007] Dividing the conductivity of a specific stimulated brain region of a stimulation object into an n*n region to obtain a discrete induced electromotive force;

[0008] Determining the conductivity at the target point of a specific brain region of the stimulation object based on the discrete induced electromotive force;

[0009] Determining the current density at the target point of a specific brain region based on the conductivity and a static magnetic field.

[0010] Optionally, the expression of the induced electromotive force is as follows:

[0011]

[0012] Wherein, σ is the conductivity at the target point of the specific brain region of the stimulation object, ρ0 is the density, p is the sound pressure, v is the vibration velocity caused by the linear array ultrasonic transducer at the target point of the specific brain region, B0 is the static magnetic field, R is the phasor difference between the field point and the source point, μ0 is the magnetic permeability of vacuum, d is the integral symbol representing an infinitesimal increment, dl is the infinitesimal line element along the detection coil, is the Hamilton operator, which represents the differentiation with respect to the source point r' here, and dv′ is the infinitesimal volume element at the target point of the brain region.

[0013] Based on the above method in the present invention, the present invention further provides a transcranial magnetoacoustic coupling stimulation device, and the stimulation device includes:

[0014] an ultrasonic focusing module, a stimulation object fixing module, and a stimulation current detection module;

[0015] The ultrasonic focusing module is used to achieve focused stimulation;

[0016] The stimulation object fixing module is used to fix the stimulation object;

[0017] The stimulation current detection module is used to achieve real-time monitoring of the current density at the target point of the specific brain region of the stimulation object.

[0018] Optionally, the ultrasonic focusing module specifically includes: a linear array ultrasonic transducer, a linear array ultrasonic transducer transmitting and receiving system, and a computer control subsystem;

[0019] The linear array ultrasonic transducer is used to stimulate the target point of the brain region through acoustic beam focusing;

[0020] The linear array ultrasonic transducer transmitting and receiving system is connected to the linear array ultrasonic transducer, and the linear array ultrasonic transducer transmitting and receiving system is used to adjust the deflection of the acoustic beam through delay setting during acoustic beam focusing to achieve acoustic beam interference and change the position of the focus;

[0021] The computer control subsystem is connected to the linear array ultrasonic transducer transmitting and receiving system, and the computer control subsystem is used to provide stimulation parameter requirements for the linear array ultrasonic transducer transmitting and receiving system according to the position of the specific brain region target point to be stimulated, and the linear array ultrasonic transducer transmitting and receiving system sends specific delay parameters and stimulation waveforms to the linear array ultrasonic transducer to achieve focused stimulation.

[0022] Optionally, the stimulation object fixing module includes: a coupling medium and a static magnetic field;

[0023] The coupling medium is used to fix the stimulation object and also to provide a coupling channel between the linear array ultrasonic transducer and the stimulation object to achieve effective stimulation of ultrasonic waves;

[0024] The static magnetic field is orthogonal to the stimulating ultrasonic waves provided by the linear array ultrasonic transducer.

[0025] Optionally, the stimulating current detection module includes: a detection coil and a signal processing system;

[0026] The detection coil is used to receive the induced electric field signal generated by the motional current while the linear array ultrasonic transducer transmitting and receiving system performs focused stimulation. The received induced electric field signal directly obtains the conductivity of the target point in a specific brain region of the stimulation object through a conductivity inversion algorithm, and uses the conductivity and the static magnetic field to directly obtain the current density of the target point in the specific brain region, realizing real-time monitoring of the current density at the target point 8 in the specific brain region 7 of the stimulation object.

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

[0028] The present invention can realize the coupled stimulation of ultrasound and static magnetic field under the high magnetic field strength of magnetic resonance. The stimulating current density can be stronger, and it is also compatible with magnetic resonance and is expected to realize the integration of stimulation and magnetic resonance imaging, that is, the integration of treatment and detection;

[0029] The present invention uses a detection coil to realize real-time monitoring of the stimulating current density, which can not only accurately obtain the stimulation position, but also realize the quantification of stimulation, helping to accurately evaluate the stimulation effect;

[0030] The present invention uses a non-magnetic linear array ultrasonic transducer. By using the focusing principle, it can not only realize precise focused stimulation of any target point in the brain region of the stimulation object, but also realize simultaneous stimulation of multiple target points by setting different focusing principles, and can also realize stimulation under magnetic resonance, realizing treatment and multi-modal imaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0032] Figure 1 It is a schematic structural diagram of a focused transcranial magnetoacoustic coupling stimulation device according to an embodiment of the present invention.

[0033] Symbol Explanation:

[0034] 1 - Linear array ultrasonic transducer, 2 - Coupling medium, 3 - Detection coil, 4 - Linear array ultrasonic transducer transmitting and receiving system, 5 - Signal processing system, 6 - Computer control subsystem, 7 - Stimulation object, 8 - Brain region target, 9 - Static magnetic field. Detailed implementation manners

[0035] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0036] The object of the present invention is to provide a non-invasive deep brain precise stimulation method and device based on transcranial magnetoacoustic coupling for realizing non-invasive electrical stimulation of the brain with high spatial resolution.

[0037] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific implementation manners.

[0038] The transcranial magnetoacoustic coupling stimulation principle of the present invention is as follows: The stimulation object is placed in a static magnetic field, and the ultrasonic wave and the static magnetic field act on the stimulation object together. The linear array ultrasonic transducer transmitting and receiving system is used to control the focusing of the linear array ultrasonic transducer on a specific target in the brain region of the stimulation object, generating high-frequency motional electric stimulation at the focal point. At the same time, the detection coil receives the induced electric signal of the motional electric stimulation, directly reconstructing the conductivity information at the focal point, thereby obtaining the motional current for real-time monitoring of the stimulation intensity and the stimulation position. The prominent advantages of this method are as follows: First, the static magnetic field for stimulation can be a halbach magnet or a U-shaped permanent magnet, or a superconducting magnet of magnetic resonance. The magnetic field intensity of the superconducting magnet of magnetic resonance can be 1.5T, 3T, or 9.4T. Second, the detection coil is used to monitor the stimulation current and the stimulation position of the transcranial magnetoacoustic coupling stimulation in real time. Third, the linear array ultrasonic transducer adopted has no magnetism and can be directly applied in the magnetic resonance magnetic field, being compatible with the magnetic resonance system. Moreover, through the focusing principle, multi-target acoustic beam focusing of the linear array ultrasonic transducer can be realized, thereby achieving the effect of multi-target synchronous stimulation.

[0039] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific implementation manners.

[0040] Figure 1 For the embodiments of the present invention Figure 1 This is the structural schematic diagram of the transcranial magnetoacoustic coupling stimulation device of the present invention. Combined with Figure 1The transcranial magnetoacoustic coupling stimulation device of the present invention comprises three parts: an ultrasonic focusing module, a stimulation object fixing module, and a stimulation current detection module.

[0041] The ultrasonic focusing module includes an excitation module which includes a linear array ultrasonic transducer 1, a linear array ultrasonic transducer transmitting and receiving system 4, and a computer control subsystem 6. The linear array ultrasonic transducer realizes the stimulation of the brain region target point through acoustic beam focusing. When performing acoustic beam focusing, the linear array ultrasonic transducer transmitting and receiving system 4 adjusts the deflection of the acoustic beam through delay setting to achieve acoustic beam interference and the change of the focus position. It can not only achieve central position focusing but also deflection focusing. The purpose is to achieve precise stimulation at any brain region target point 8 of the entire stimulation object 7. The computer control subsystem 6 provides the stimulation parameter requirements for the linear array ultrasonic transducer transmitting and receiving system 4 according to the position of the specific brain region target point 8 to be stimulated. Then, the linear array ultrasonic transducer transmitting and receiving system 4 sends specific delay parameters and stimulation waveforms to the linear array ultrasonic transducer 1 to achieve focused stimulation.

[0042] The stimulation object fixing module includes a coupling medium 2 and a static magnetic field 9. The coupling medium 2 not only fixes the stimulation object 7 but also provides a coupling channel between the linear array ultrasonic transducer 1 and the stimulation object 7 to achieve effective stimulation of ultrasonic waves. The static magnetic field 2 for stimulation can be provided by a halbach magnet or a U-shaped permanent magnet, or can be provided by a magnetic resonance superconducting magnet. The magnetic field intensity of the magnetic resonance superconducting magnet can be 1.5T, 3T, or 9.4T. The stimulation object is placed in the static magnetic field 9, and the static magnetic field 9 is orthogonal to the stimulation ultrasonic waves provided by the linear array ultrasonic transducer 1.

[0043] The stimulation current detection module includes a detection coil 3, a signal processing system 5, and a computer control subsystem 6. First, while the linear array ultrasonic transducer transmitting and receiving system 4 performs focused stimulation, the detection coil 3 receives the induced electric field signal generated by the motional current. The received induced electric field signal directly obtains the conductivity of the specific brain region target point 8 of the stimulation object 7 through the conductivity inversion algorithm, and uses the conductivity and the static magnetic field to directly obtain the current density of the specific brain region target point 8, realizing the real-time monitoring of the current density at the specific brain region target point 8 of the stimulation object 7. The specific current density reconstruction process is described as follows:

[0044] Assume that the conductivity at the specific brain region target point 8 of the stimulation object 7 is σ, the vibration velocity caused by the linear array ultrasonic transducer 1 at the specific brain region target point 8 is v, and the static magnetic field is B0. Then, a motional current J is formed at the focus point e1 :

[0045] J e1 = σv×B0 (1)

[0046] Changes in current density will cause changes in the spatial magnetic field. The vector magnetic potential A generated by motional current can be expressed as the volume integral of J e1 :

[0047]

[0048] R represents the phasor difference between the field point and the source point, and μ0 is the magnetic permeability of vacuum.

[0049] Then the electric field E generated by J e1 is:

[0050]

[0051] Combined with the sound pressure - velocity coupling equation:

[0052]

[0053] where ρ0 is the density and p is the sound pressure;

[0054] The induced electromotive force ξ(t) detected by the detection coil 3 is:

[0055]

[0056] Let Its meaning is the distribution of the vector magnetic potential in the target body when a direct current of 1 is passed through the detection coil 3.

[0057] Divide the conductivity of the specific stimulated brain region of the stimulation object into n*n regions, and combined with to obtain the discrete induced electromotive force:

[0058]

[0059] where is the value of the conductivity of each sub-region, v(e i ,t k ) is the vibration velocity of the mass point in each sub-region, which is a function of time and space, and S(e i ) is the vector magnetic potential in each sub-region, which is only a function of space.

[0060] Furthermore, let to obtain:

[0061]

[0062] Thus, the solution of the conductivity matrix can be transformed into the solution of a matrix equation. The left end of formula (6) is the value of the induced electromotive force measured in the coil at n moments, which is an n×1 order matrix is an array with n elements, and each element is an n×n dimensional matrix; the quantity to be solved is an n-order square matrix. From this, the value of the conductivity is obtained through matrix operations. Further, the current density at the target point 8 in a specific brain region is obtained from the conductivity and the static magnetic field 9.

[0063] The various embodiments in this specification are described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. For the same or similar parts among the various embodiments, reference can be made to each other.

[0064] Specific examples are used in this article to elaborate on the principles and implementation manners of the present invention. The descriptions of the above embodiments are only used to help understand the method and its core idea of the present invention. At the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A transcranial magneto-acoustic coupling stimulation device, characterized in that, The stimulation device includes: an ultrasonic focusing module, a stimulation object fixing module, and a stimulation current detection module; The ultrasonic focusing module is used to achieve focused stimulation; The stimulation object fixing module is used to fix the stimulation object; The stimulation current detection module is used to achieve real-time monitoring of the current density at the target point of a specific brain region of the stimulation object; The ultrasonic focusing module includes: a linear array ultrasonic transducer, a linear array ultrasonic transducer transmitting and receiving system, and a computer control subsystem; The processing process of the stimulation current detection module specifically includes: Detecting the induced electromotive force; Dividing the conductivity of a specific stimulated brain region of the stimulation object into an n*n region to obtain discrete induced electromotive forces; Determining the conductivity at the target point of a specific brain region of the stimulation object based on the discrete induced electromotive forces; Determining the current density at the target point of a specific brain region based on the conductivity and the static magnetic field; The expression of the induced electromotive force is as follows: ； Among them, is the conductivity at the target point of the specific brain region of the stimulation object, is the density, is the sound pressure, is the vibration velocity caused by the linear array ultrasonic transducer at the target point of the specific brain region, is the static magnetic field, is the phasor difference between the field point and the source point, is the vacuum permeability, d is the integral symbol, representing an infinitesimal increment, is the infinitesimal line element along the detection coil, is the Hamilton operator, which represents the differentiation with respect to the source point r' here, is the infinitesimal volume element at the target point of the brain region; The determining the conductivity at the target point of a specific brain region of the stimulation object based on the discrete induced electromotive forces specifically includes: The values of the induced electromotive force at n moments The expression is as follows: ； ； Among them, is an array with n elements, and each element is a matrix of dimension; is the vibration velocity of the mass points in each sub-region, which is a function of time and space; is the vector magnetic potential in each sub-region, which is a function of space; is the value of the conductivity of each region, which is an n-order square matrix.

2. The transcranial magneto-acoustic coupling stimulation device according to claim 1, characterized in that: The linear array ultrasonic transducer is used to stimulate the target point of the brain region through acoustic beam focusing; The linear array ultrasonic transducer transmitting and receiving system is connected to the linear array ultrasonic transducer. The linear array ultrasonic transducer transmitting and receiving system is used to adjust the deflection of the acoustic beam through delay setting during acoustic beam focusing to achieve acoustic beam interference and change the position of the focus; The computer control subsystem is connected to the linear array ultrasonic transducer transmitting and receiving system. The computer control subsystem is used to provide stimulation parameter requirements for the linear array ultrasonic transducer transmitting and receiving system according to the position of the specific brain region target point to be stimulated. The linear array ultrasonic transducer transmitting and receiving system sends specific delay parameters and stimulation waveforms to the linear array ultrasonic transducer to achieve focused stimulation.

3. The transcranial magneto-acoustic coupling stimulation device according to claim 2, characterized in that, The stimulation object fixing module includes: a coupling medium and a static magnetic field; The coupling medium is used to fix the stimulation object and also to provide a coupling channel between the linear array ultrasonic transducer and the stimulation object to achieve effective stimulation of ultrasonic waves; The static magnetic field is orthogonal to the stimulating ultrasonic waves provided by the linear array ultrasonic transducer.

4. The transcranial magneto-acoustic coupling stimulation device according to claim 2, characterized in that, The stimulation current detection module includes: a detection coil and a signal processing system; The detection coil is used to receive the induced electric field signal generated by the motional current while the linear array ultrasonic transducer transmitting and receiving system is performing focused stimulation. The received induced electric field signal directly obtains the conductivity of the target point of a specific brain region of the stimulation object through the conductivity inversion algorithm, and directly obtains the current density of the target point of a specific brain region by using the conductivity and the static magnetic field to achieve real-time monitoring of the current density at the target point of a specific brain region of the stimulation object.

Images