CN114191720A - Cross coil for deep transcranial magnetic stimulation - Google Patents

Cross coil for deep transcranial magnetic stimulation Download PDF

Info

Publication number
CN114191720A
CN114191720A CN202111559815.XA CN202111559815A CN114191720A CN 114191720 A CN114191720 A CN 114191720A CN 202111559815 A CN202111559815 A CN 202111559815A CN 114191720 A CN114191720 A CN 114191720A
Authority
CN
China
Prior art keywords
coil
halo
stimulation
shaped
depth
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202111559815.XA
Other languages
Chinese (zh)
Inventor
熊慧
李青宇
刘近贞
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Tianjin Polytechnic University
Original Assignee
Tianjin Polytechnic University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Tianjin Polytechnic University filed Critical Tianjin Polytechnic University
Priority to CN202111559815.XA priority Critical patent/CN114191720A/en
Publication of CN114191720A publication Critical patent/CN114191720A/en
Pending legal-status Critical Current

Links

Images

Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N2/00—Magnetotherapy
    • A61N2/02—Magnetotherapy using magnetic fields produced by coils, including single turn loops or electromagnets
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N2/00—Magnetotherapy
    • A61N2/004—Magnetotherapy specially adapted for a specific therapy
    • A61N2/006—Magnetotherapy specially adapted for a specific therapy for magnetic stimulation of nerve tissue

Landscapes

  • Health & Medical Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Biomedical Technology (AREA)
  • Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
  • Radiology & Medical Imaging (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Neurology (AREA)
  • Magnetic Treatment Devices (AREA)

Abstract

The invention provides a cross type transcranial magnetic stimulation coil for improving the stimulation depth, which consists of an 8-shaped coil and a Halo coil, wherein the Halo coil surrounds the short shaft of the 8-shaped coil, and the upper boundary of the Halo coil is always above the center of the 8-shaped coil. The two parts of the 8-shaped coil are respectively introduced with currents in opposite directions for generating a focusing magnetic field, and the current direction of the upper boundary of the Halo coil is consistent with the current direction of the tangent position of the 8-shaped coil, so that the advantage of stimulation depth is provided. According to the invention, the influence of the Halo coil on the 8-shaped coil is changed by changing the included angle and the distance between the Halo coil and the 8-shaped coil, so that the change relation between the focusing property of the crossed coil and the stimulation depth is balanced. Based on evaluation criteria, the present invention has larger stimulation intensity, smaller focal area and better stimulation depth compared with the existing deep HFA stimulation coil, which provides a potential new tool for the transcranial magnetic stimulation research and the treatment of the deep brain dysfunctional diseases.

Description

Cross coil for deep transcranial magnetic stimulation
Technical Field
The invention belongs to the technical field of transcranial magnetic stimulation, and particularly relates to a design of a crossed transcranial magnetic stimulation coil capable of remarkably improving the stimulation depth.
Background
Transcranial Magnetic Stimulation (TMS), a non-invasive method of brain Stimulation, is an important tool for studying human brain functional tissues and also a powerful tool for treating mental disorders. The TMS coil placed on the surface of the head of a patient is introduced with alternating current, a pulse magnetic field which can penetrate through the scalp and the skull can be generated, an induction electric field is induced in brain tissue, the membrane potential of cerebral cortex nerve cells is further changed, the excitation of the cortex can be influenced in a mode which is not completely understood, and a series of functional activities of cerebral neurons are triggered, so that the purposes of detecting and constructing a functional brain diagram or diagnosing and treating diseases are achieved.
Magnetic stimulation coils are important carriers for time-varying magnetic fields to induce induced electric fields. When the coil is connected with pulse current, a transient magnetic field is generated, and the spatial form of the transient magnetic field is mainly related to the distribution of current elements of the coil. The distribution of the current elements is mainly determined by the structure and the position of the coil. Thus, the characteristics of the stimulation coil directly influence the morphological distribution of the transient induced magnetic field. It has been shown that there is a non-linear trade-off between depth of stimulation and focality when the stimulation coil is active, i.e. an increase in depth of stimulation is often accompanied by an increase in focal area, while an improvement in focality comes at the expense of depth of stimulation. Wherein the stimulation depth reflects the penetration capability of the stimulation coil during magnetic stimulation. In general, the depth of stimulation is represented by the maximum distance that the electric field at the cortex decays to half its maximum value. Focus is defined as the area where the electric field strength exceeds half relative to the maximum at a given depth (e.g., the cortical surface), reflecting the magnetic convergence properties of the stimulation coil.
Researchers have designed various forms of coils and coil arrays for different purposes, such as improving focusing or enriching the diversity of stimuli. At present, a circular coil with a large stimulation area is multipurpose for peripheral nerve stimulation and detection of the integrity of a nerve pathway, and coils for disease treatment have the forms of a figure-8 coil, an H-shaped coil, a biconical coil and the like. In order to increase the stimulation depth of the coil, researchers try to arrange the 8-shaped coil and a Halo coil in parallel to form the HFA coil, wherein the effect of the Halo coil can generate stimulation effects on areas of the forehead, the ears, the hindbrain and the like of a human body, and side effects in medical treatment are easily caused. In addition, the technology has some problems at present, and most prominently, the target point is poor in pertinence, and accurate magnetic focusing is difficult to achieve. Therefore, focusing of the coil action is also required to be considered while increasing the depth of stimulation by the coil.
Disclosure of Invention
Aiming at the defects of the existing TMS technology, the invention provides a crossed coil for deep transcranial magnetic stimulation, which solves the problem of low stimulation depth by combining an 8-shaped coil and a Halo coil, enhances the stimulation intensity of tissues such as cerebral cortex and the like, and does not seriously lose the focusing property.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
the crossed coil consists of an 8-shaped coil and a Halo coil. The 8-shaped coil is positioned on a plane 5mm above the top point of the ball head model, the plane where the Halo coil is positioned passes through the tangent line of the 8-shaped coil, and the current direction of the upper boundary of the Halo coil is consistent with the current direction of the tangent position of the 8-shaped coil. To ensure that the Halo coil and the figure-8 coil do not contact each other, the center of the upper boundary of the Halo coil is 14mm away from the center of the figure-8 coil when the Halo coil is not moved.
The invention further improves the following steps: the included angle between the Halo coil and the 8-shaped coil is variable, and the height of the Halo coil is variable. In the rotating and moving processes, the geometric center of the upper boundary of the Halo coil, the geometric center of the 8-shaped coil and the spherical center of the spherical model are always on the same straight line.
The invention further improves the following steps: the included angle range of the Halo coil and the 8-shaped coil is 30-75 degrees, the interval is 15 degrees, the upward moving range of the Halo coil is 0-90mm, the interval is 10mm, and the change of the included angle of the coil cannot cause the change of the distance between two centers of the coil.
Compared with the prior art, the invention has the following advantages: the invention provides a cross-type coil structure which can obviously improve the stimulation depth, and has simple structure and easy construction. The upper boundary current direction of a Halo coil in the crossed coil is consistent with the current direction at the tangent position of the 8-shaped coil, so that the stimulation intensity below the center of the 8-shaped coil can be enhanced, and the stimulation depth of transcranial magnetic stimulation is obviously improved. The balance relation between the focusing performance and the stimulation depth can be adjusted to different degrees by changing the height of the Halo coil and the included angle between the Halo coil and the 8-shaped coil. Therefore, the cross-type coil provided by the invention can achieve the effects of increasing the stimulation intensity and the stimulation depth without losing the focusing property, and provides a new reference for treating deep brain diseases.
Drawings
Fig. 1 shows a schematic structure diagram based on a double-layer ball head model, the included angle and the current direction of a crossed coil and the hall coil when the hall coil does not move upwards.
FIG. 2 is a change broken line diagram of electric field intensity moving upwards along with a Halo coil for different distances based on a double-layer ball head model under the condition that the included angle between an 8-shaped coil and the Halo coil is different.
FIG. 3 is a change broken line diagram based on a double-layer ball head model, wherein the focusing area moves upwards along with a Halo coil for different distances under the condition that the included angle between an 8-shaped coil and the Halo coil is different.
FIG. 4 is a change broken line diagram of the stimulation depth moving upwards along with the Halo coil for different distances based on a double-layer ball head model under the condition that the included angle between the 8-shaped coil and the Halo coil is different.
Fig. 5 is a schematic diagram of the combination of an HFA coil and a human head model.
Fig. 6 is an electric field distribution diagram of the HFA coil applied to the human head model.
FIG. 7 is a schematic combination diagram of a cross-shaped coil and a human head model when the included angle between the 8-shaped coil and the Halo coil is 45 degrees and the Halo coil does not move upwards.
FIG. 8 is an electric field distribution diagram of a cross-shaped coil acting on a human head model when the angle between the 8-shaped coil and the Halo coil is 45 degrees and the Halo coil does not move upwards.
Detailed Description
The transcranial magnetic stimulation cross-type coil of the present invention will be described in further detail with reference to the accompanying drawings.
The 8-shaped coil adopted in the invention is Type9925 of Magstim company, the inner diameter of the coil is 56mm, the outer diameter of the coil is 87mm, the coil is horizontally placed above the scalp of the brain for 5mm, and the number of turns of the coil is 9 turns. The inner radius of the Halo coil is 138mm, the outer radius is 150mm, and the number of coil turns is 6 turns. The 8-shaped coil and the Halo coil are formed by winding copper wires with the same size, and the cross section area of the coil is 6mm x 1.75 mm.
Fig. 1 shows a specific structure and a schematic current direction diagram of a cross-type coil when a Halo coil does not move upwards based on a double-layer ball model, the Halo coil takes the structure shown in fig. 1 as an initial structure and always moves along the arrow direction in fig. one, and the moving distance is represented by d (mm). The current directions of the three coil units at the top point of the sphere are consistent, and according to the Maxwell equation set, the electric fields below the center of the coil have superposition benefits, which is beneficial to enhancing the stimulation intensity and the stimulation depth. The external sphere radius of the spherical model is 85mm, and the spherical model is used for representing the human head structure in biology; the inner sphere radius is 70mm, which is used in the present invention to represent the cortical layer of the human brain in biology.
In order to analyze the influence of different parameter changes in the crossed coil on the stimulation intensity, the focusing performance and the stimulation depth of the cortical layer, reasonable evaluation indexes need to be formulated to obtain the optimal coil included angle and the optimal Halo moving-up distance. Wherein the performance index of the stimulation intensity is the maximum induction electric field intensity E of the cortexmaxThe stimulus intensity should meet a minimum stimulus threshold Eth(100V/m). The depth of stimulation is defined as the maximum E of the surface electric field of the cortexmaxTo 1/2EmaxMaximum distance of, stimulation depth d1/2The larger the stimulation, the better the stimulation performance. The quality of the focusing performance is to compare the size of the focusing area S1/2Is greater than 1/2EmaxIs calculated by the following formula:
Figure BSA0000261160980000031
wherein V1/2Greater than 1/2E within the cortex of the brainmaxVolume of (d)1/2Is the depth of stimulation. Stimulation depth d of crossed coils1/2The larger the size, the better the effect of the coil in terms of stimulation depth, and the ability to stimulate deep brain tissue, with a powerful impact on the treatment of deep disease target areas.
Fig. 2 reflects the effect of the magnitude of the upward movement distance of the Halo coil on the stimulation intensity in the cross-shaped coils with different included angles. It can be seen that under the condition of the same included angle of the coils, the upward movement of the Halo coil can reduce the beneficial influence of the upper boundary of the Halo coil on the center of the 8-shaped coil, so that the stimulation intensity is inhibited. When the included angle of the crossed coil is different, and the upward movement distance of the Halo coil is the same, the larger the included angle of the coil is, and the larger the stimulation intensity is, the more the law exists. This is due to the fact that the larger the angle of the crossed coil, the greater the beneficial effect provided by the upper boundary of the Halo coil, thereby increasing the stimulation intensity. It is worth mentioning that the magnitude of the electric field strength in the listed variations of angle and movement distance always exceeds 100V/m, which satisfies the minimum stimulation threshold condition of the cortex.
Fig. 3 and 4 show the effect of different included angle angles and distances in the crossed coils on the focal area and the stimulation depth, respectively. When the included angle of the crossed coil is respectively 30 degrees, 45 degrees and 60 degrees, the focusing area and the stimulation depth of the coil are reduced along with the upward movement of the Halo coil, namely the focusing performance of the coil is improved, and the advantage in the aspect of the stimulation depth is weakened. This also illustrates the trade-off between focality and depth of stimulation in transcranial magnetic stimulation.
In particular, when the angle of the crossed coil is 75 °, the upward shift of the Halo coil has little effect on the depth of the stimulation, but has a significant effect on the focal area. When the distance of upward movement of the Halo coil exceeds 70mm, the focusing area of the cross-type coil increases exponentially. This is because when the Halo coil moves up more than 70mm, the lower boundary of the Halo coil will gradually approach the lower right side of the spherical phantom, creating a second local focus, thereby increasing the area of focus of the stimulus and severely losing focus.
In order to determine the optimal parameters of the cross coil, which can simultaneously have a smaller focusing area, a larger stimulation intensity and a stimulation depth, the following criteria are established: (1) the stimulation intensity of the cross-type coil is more than 150V/m; (2) the focusing area of the crossed coil is less than 30cm2(ii) a (3) The stimulation depth of the crossed coil is greater than 17 mm. The crossed coils meeting the three conditions are two, the included angle is 45 degrees, the crossed coil when the Halo coil moves upwards and the included angle are 45 degrees, and the crossed coil when the Halo coil moves upwards by 10 mm.
Fig. 5 is a schematic diagram of the assembly of the HFA coil placed on a real human head model. Wherein the 8-shaped coil is parallel to the Halo coil, and the distance between the two planes is 100 mm. Figure 6 shows the electric field profile of an HFA coil applied to a real human head model. The three-dimensional and sagittal plots of electric field distribution show that the HFA coil produces a broader electric field distribution at the forehead of the human head due to the Halo coil, and accordingly produces stimulation at the ear and hindbrain regions.
Fig. 7 shows a combined schematic diagram of a cross-shaped coil placed on a real human head model with an included angle of 45 ° and without upward movement of the Halo coil, wherein the distance between the center of the upper boundary of the Halo coil and the geometric center of the 8-shaped coil is 14 mm. Fig. 8 shows the electric field distribution diagram of the cross-type coil acting on the real human head model. As can be seen from the three-dimensional electric field distribution diagram, the crossed coil generates a focusing electric field at the vertex of the human head and does not influence other tissues of the human head.
From the sagittal view of the electric field distribution, even though the stimulation area generated by the cross type coil at the vertex of the head is slightly wider than that generated by the HFA compared with the HFA coil, the cross type coil does not generate stimulation at the forehead, the hindbrain and other parts of the human head, and the stimulation depth of the cross type coil is obviously better than that of the HFA coil. In addition, under the same stimulation condition, the maximum induced electric field intensity of the HFA coil and the cross-type coil on the surface layer of the head model is 329V/m and 552V/m respectively, and the stimulation intensity of the cross-type coil is increased by 67.78% compared with that of the HFA coil.
By combining the above analysis, the stimulation intensity of the cross coil is more than 150V/m; (2) the focusing area of the crossed coil is less than 30cm2(ii) a (3) The stimulation depth of the crossed coil is larger than 17mm, the included angles of three standards are 45 degrees, the crossed coil without upward moving of the Halo coil has the comprehensive advantages of remarkable stimulation intensity, good focusing property and deeper stimulation depth, and a new choice is provided for the transcranial magnetic stimulation for the stimulation of deep brain structures. The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims (5)

1. A cross-type coil for improving the depth of transcranial magnetic stimulation is characterized in that the cross-type coil is composed of a 8-shaped coil with excellent focusing performance and a Halo coil for deep stimulation. The geometric center of the upper boundary of the Halo coil and the geometric center of the 8-shaped coil are always on the same straight line.
2. The crossed coil of claim 1, wherein the left circular coil current direction of the figure-8 coil is clockwise and the right circular coil current direction is counter-clockwise. The direction of the current on the upper boundary of the Halo coil is consistent with the direction of the current at the tangent of the two coils of the 8-shaped coil.
3. The crossed coil according to claim 1, characterized in that the geometry of the figure-8 coil and the Halo coil is fixed, and the upper boundary of the Halo coil is always above the figure-8 coil and does not contact the upper surface of the figure-8 coil according to the coil winding turn size limitation.
4. The crossed coil of claim 1, wherein the angle between the figure-8 coil and the Halo coil in the crossed coil is variable.
5. The crossed coil according to claim 1, wherein the height of the Halo coil in the crossed coil is variable, so as to adjust the distance between the Halo coil and the 8-shaped coil, and achieve the purpose of changing the stimulation depth and the focusing area.
CN202111559815.XA 2021-12-20 2021-12-20 Cross coil for deep transcranial magnetic stimulation Pending CN114191720A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202111559815.XA CN114191720A (en) 2021-12-20 2021-12-20 Cross coil for deep transcranial magnetic stimulation

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202111559815.XA CN114191720A (en) 2021-12-20 2021-12-20 Cross coil for deep transcranial magnetic stimulation

Publications (1)

Publication Number Publication Date
CN114191720A true CN114191720A (en) 2022-03-18

Family

ID=80655333

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202111559815.XA Pending CN114191720A (en) 2021-12-20 2021-12-20 Cross coil for deep transcranial magnetic stimulation

Country Status (1)

Country Link
CN (1) CN114191720A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114796875A (en) * 2022-06-30 2022-07-29 中国科学院自动化研究所 Electromagnetic stimulation method, device, equipment and readable storage medium
CN115762303A (en) * 2022-11-07 2023-03-07 深圳职业技术学院 System construction method of transcranial magnetic stimulation coil electromagnetic field simulation system
CN115887932A (en) * 2022-11-09 2023-04-04 成都理工大学 Tangential surrounding type spatial array and system for craniocerebral deep noninvasive focusing stimulation

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114796875A (en) * 2022-06-30 2022-07-29 中国科学院自动化研究所 Electromagnetic stimulation method, device, equipment and readable storage medium
CN114796875B (en) * 2022-06-30 2022-09-27 中国科学院自动化研究所 Electromagnetic stimulation method, device, equipment and readable storage medium
CN115762303A (en) * 2022-11-07 2023-03-07 深圳职业技术学院 System construction method of transcranial magnetic stimulation coil electromagnetic field simulation system
CN115762303B (en) * 2022-11-07 2023-08-18 深圳职业技术学院 System construction method of transcranial magnetic stimulation coil electromagnetic field simulation system
CN115887932A (en) * 2022-11-09 2023-04-04 成都理工大学 Tangential surrounding type spatial array and system for craniocerebral deep noninvasive focusing stimulation
CN115887932B (en) * 2022-11-09 2023-08-29 成都理工大学 Tangential surrounding type space array and system for deep craniocerebral noninvasive focusing stimulation

Similar Documents

Publication Publication Date Title
CN114191720A (en) Cross coil for deep transcranial magnetic stimulation
KR102121673B1 (en) Coil and magnetic stimulator using same
Cohen et al. Effects of coil design on delivery of focal magnetic stimulation. Technical considerations
EP2958621B1 (en) Circular coils for deep transcranial magnetic stimulation
Hsu et al. A 3-D differential coil design for localized magnetic stimulation
AU2002229129B9 (en) Coil for magnetic stimulation
US9808642B2 (en) Circular coils for deep transcranial magnetic stimulation
Rastogi et al. Investigation of coil designs for transcranial magnetic stimulation on mice
JP2021514247A (en) Magnetic stimulation coils and ferromagnetic components for therapeutic and diagnostic procedures
CN102727997B (en) Two 8-shaped cerebral magnetic stimulation coil
US10792508B2 (en) Quadruple butterfly coil
Rastogi Novel coil designs for different neurological disorders in transcranial magnetic stimulation
CN105435371A (en) 8-shaped coil transcranial magnetic stimulation system based on magnetic resonant coupling principle
March et al. Focused and deep brain magnetic stimulation using new coil design in mice
CN109745621A (en) A kind of volume body coils tangent for more circles of deep transcranial magnetic stimulation
CN111135465A (en) Deep transcranial magnetic coil stimulation device based on time interference
CN109011161A (en) A kind of reverse winding and its design method for transcranial magnetic stimulation
Guadagnin et al. Modelling of deep transcranial magnetic stimulation: different coil configurations
KR100696724B1 (en) Magnetic stimulators with improved magnetic field localization
CN217593617U (en) Double-layer cap-shaped transcranial magnetic coil
Song et al. Optimal Design of Transcupoint Magnetic Stimulation Coil with Trade-Off Between Stimulation Effect and Joule Heat Energy
Ding et al. Numerical simulations of figure-8 coil during transcranial magnetic stimulation
Hao et al. Simulation study on coil design for transcranial magnetic stimulation
Lu et al. Deep transcranial magnetic stimulation with improved focality using figure-of-eight and Halo coils
Fang et al. Focalized Brain Transcranial Magnetic Stimulation with the Utilization of a Field Shaper and a Crescent Ferromagnetic Core

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination