Magnetic resonance head function detection radio frequency coil and radio frequency detection system

Abstract

The utility model relates to the technical field of magnetic resonance head function detection radio frequency coils, and discloses a magnetic resonance head function detection radio frequency coil and a radio frequency detection system. According to the magnetic resonance head function detection radio frequency coil, the distance between the I-shaped structure and the first I-shaped assembly and the distance between the I-shaped structure and the second I-shaped assembly are controlled, so that a user to be detected can see an object through the gap between the I-shaped structure and the first I-shaped assembly; and the birdcage structure generates a uniform magnetic field by adjusting the capacitance values of the plurality of first capacitance parts, the capacitance values of the plurality of second capacitance parts, the capacitance value of the third capacitance part and the capacitance value of the fourth capacitance part, so that the visual field of the detection coil is widened, and the detection efficiency of the radio frequency coil is improved while the detection effect of the radio frequency coil is not changed. The technical problem that in the prior art, uncomfortable humor feeling is likely to be generated during user detection is solved.

Description

Technical Field

[0001] The utility model relates to the technical field of medical image detection, in particular to a radio frequency coil for magnetic resonance head function detection and a radio frequency detection system. Background Art

[0002] Magnetic resonance imaging (MRI) technology has become an important means of clinical diagnosis in modern medicine. It has the advantages of high tissue density contrast, the ability to perform layer imaging in any orientation, and no ionizing radiation, and is being used more and more widely.

[0003] In the magnetic resonance system, the radio frequency transmitting / receiving coil is an essential component of the system, through which electromagnetic wave signals can be sent to the body; and the energy released from the body tissue can be received to form medical images, so the performance of the coil will directly affect the performance of the magnetic resonance system. At the same time, compared with other components in the magnetic resonance system, the radio frequency coil is easier to develop and optimize, so it has always been a hot topic in the field of magnetic resonance imaging.

[0004] Currently, commercial head coils use closed birdcage coils, which have high magnetic field uniformity and can use orthogonal excitation to obtain a high SNR (signal-to-noise ratio).

[0005] The birdcage structure of the coil is a relatively enclosed space, and the subjects will feel uncomfortable and claustrophobic if they stay in the MRI machine for a long time. Utility Model Content

[0006] In view of the above problems, the utility model provides a radio frequency coil for magnetic resonance head function detection, which is used to solve the technical problem in the prior art that users are prone to feel uncomfortable and claustrophobic during detection.

[0007] According to one aspect of the embodiment of the utility model, there is provided a radio frequency coil for detecting magnetic resonance head function, comprising:

[0008] 2N T-shaped structures, a plurality of first capacitors, a plurality of second capacitors, a plurality of third capacitors, a plurality of fourth capacitors, N first unidirectional conductive members and an I-shaped structure, wherein every two T-shaped structures are connected by a first unidirectional conductive member to form an I-shaped assembly; the I-shaped assembly includes a first I-shaped assembly, a second I-shaped assembly and a plurality of third I-shaped assemblies;

[0009] The first I-shaped component and the second I-shaped component are symmetrical based on the I-shaped structure and are respectively arranged at a first preset distance from the I-shaped structure. The upper part and the lower part of the I-shaped structure are respectively connected end to end with the first I-shaped component and the second I-shaped component through the first capacitor. N is a natural number greater than 1;

[0010] The upper part and the lower part of the third I-shaped component are connected to the upper part and the lower part of the first I-shaped component through the second capacitor and the third capacitor respectively, and are arranged at a second preset distance from the first I-shaped component;

[0011] Sequentially connect the upper and lower parts of the next third I-shaped component to the upper and lower parts of the previous third I-shaped component through two fourth capacitors, respectively, and set them at a second preset distance from the previous third I-shaped component; until the upper and lower parts of the last third I-shaped component are respectively connected to the previous third I-shaped component through two fourth capacitors, and the upper and lower parts of the last third I-shaped component are also connected to the upper and lower parts of the second I-shaped component through another second capacitor and another third capacitor, and set them at a second preset distance from the previous third I-shaped component and the second I-shaped component, so as to form a birdcage structure;

[0012] Among them, the first preset distance is greater than the second preset distance, the capacitance of the first capacitor is greater than the capacitance of the fourth capacitor, and the capacitance of the first capacitor, the second capacitor, the third capacitor and the fourth capacitor are determined according to the first preset distance and the second preset distance, so that the birdcage structure generates a uniform magnetic field.

[0013] In an optional manner, the first preset distance is 78.6 mm, and the second preset distance is 49 mm.

[0014] In an optional manner, the MRI head function detection RF coil also includes two second unidirectional conductive components, wherein the anode of one of the second unidirectional conductive components is connected to one end of the third I-type component close to the first I-type component, and the cathode of one of the second unidirectional conductive components is connected to the first I-type component through a second capacitor; the anode of another of the second unidirectional conductive components is connected to one end of the third I-type component close to the second I-type component, and the cathode of another of the second unidirectional conductive components is connected to the second I-type component through another second capacitor.

[0015] In an optional manner, the I-shaped structure and the first I-shaped component form a first visual field, and the I-shaped structure and the second I-shaped component form a second visual field; the magnetic resonance head function detection radio frequency coil also includes a first visual window arranged in the first visual field, and a second visual window arranged in the second visual field.

[0016] In an optional manner, the first visible window and the second visible window are 87.5 mm long and 56 mm wide.

[0017] According to the second aspect of the embodiment of the utility model, a radio frequency detection system is also provided, comprising the magnetic resonance head function detection radio frequency coil and a head-mounted receiving array coil as described above, wherein the head-mounted receiving array coil is fixed on a flexible member, and when the flexible member is worn on a human body, the head-mounted receiving array coil is arranged to fit the wearer's lower jaw.

[0018] In an optional manner, the head-mounted receiving array coil further includes a plurality of coils arranged to overlap each other in pairs, and each coil transmits the received signal to the host computer through an independent channel.

[0019] In an optional manner, the number of the coils is 24, and the head-mounted receiving array coil composed of the 24 coils is centrally symmetrically arranged.

[0020] In an optional embodiment, the head-mounted receiving array coil is 282 mm long and 107 mm wide, and each coil has a diameter of 40 mm.

[0021] In an optional manner, a first wearing portion and a second wearing portion are further provided on the flexible member, and the first wearing portion and the second wearing portion are provided based on a head-mounted receiving array coil.

[0022] The utility model provides a radio frequency coil for detecting head functions of magnetic resonance, so that the user to be detected can see objects through the gap between the two by controlling the spacing between the I-shaped structure and the first I-shaped component and the second I-shaped component, and the birdcage structure generates a uniform magnetic field by adjusting the capacitance values ​​of the plurality of first capacitors and the capacitance values ​​of the plurality of second capacitors, thereby widening the field of view of the detection coil and solving the technical problem of the user easily generating an uncomfortable feeling of claustrophobia during detection in the prior art without changing the detection effect of the radio frequency coil.

[0023] The above description is only an overview of the technical solution of the embodiment of the utility model. In order to more clearly understand the technical means of the embodiment of the utility model, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the embodiment of the utility model more obvious and easy to understand, the specific implementation methods of the utility model are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings are only used to illustrate the embodiments and are not considered to be limitations of the present invention. In addition, the same reference symbols are used to represent the same components throughout the accompanying drawings. In the accompanying drawings:

[0025] Figure 1 The structure diagram of the radio frequency coil for magnetic resonance head function detection provided by the utility model is shown;

[0026] Figure 2 The schematic diagram of the structure of the head-mounted receiving array coil of the radio frequency detection system provided by the utility model is shown. DETAILED DESCRIPTION

[0027] The exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein.

[0028] The following is an analysis of the prior art of radio frequency coils for head function detection in combination with related technologies.

[0029] For traditional coils, different models, sizes, and types of coils need to be customized for different patients, different body sizes, and individual characteristics of the detection parts to meet the requirements of high-quality imaging. This will not only increase the patient's time and economic costs, but more importantly, it is difficult to achieve commercial universality. The existing head imaging coils are not convenient to use due to their complex structure and unreasonable design, and the imaging effect is not ideal.

[0030] In addition, most commercial coils have a fixed mechanical structure. For different patients, due to differences in body geometry, the same coil will have different filling factors, and the increase in coil filling factor contributes greatly to the improvement of SNR. The design of compact coils can achieve a maximum filling factor. However, for traditional coils, in order to maximize the coil filling factor in the system, it is necessary to customize coils of different models, sizes, and types for different patients, different body sizes, and individual characteristics of the detection site to meet high-quality imaging requirements. This will not only increase the patient's time and economic costs, but more importantly, it is difficult to achieve commercial universality. The application of the equipment will be greatly limited.

[0031] The present application provides a radio frequency coil for detecting head functions by magnetic resonance, which is used to solve the technical problem that users of existing radio frequency coils for detecting head functions are prone to feel uncomfortable and claustrophobic during detection.

[0032] Figure 1 The utility model shows a structure diagram of a radio frequency coil for detecting head function by magnetic resonance, which comprises:

[0033] 2N T-shaped structures, a plurality of first capacitors C1, a plurality of second capacitors C2, a plurality of third capacitors C3, a plurality of fourth capacitors C4, N first unidirectional conductive members D1 and an I-shaped structure 10, wherein every two T-shaped structures are connected by one first unidirectional conductive member D1 to form an I-shaped assembly; the I-shaped assembly includes a first I-shaped assembly 11, a second I-shaped assembly 12 and a plurality of third I-shaped assemblies 13;

[0034] The first I-shaped component 11 and the second I-shaped component 12 are symmetrical based on the I-shaped structure 10, and are respectively arranged at a first preset distance from the I-shaped structure 10. The upper part and the lower part of the I-shaped structure 10 are respectively connected end to end with the first I-shaped component 11 and the second I-shaped component 12 through the first capacitor C1; N is a natural number greater than 1;

[0035] The upper and lower parts of a third I-shaped component 13 are connected to the upper and lower parts of the first I-shaped component 11 through a second capacitor C2 and a third capacitor C3 respectively, and are spaced apart from the first I-shaped component 11 by a second preset distance;

[0036] The upper and lower parts of the next third I-shaped component 13 are sequentially connected to the upper and lower parts of the previous third I-shaped component 13 through two fourth capacitors C4, respectively, and are spaced apart from the previous third I-shaped component 13 by a second preset distance; until the upper and lower parts of the last third I-shaped component 13 are respectively connected to the previous third I-shaped component 13 through two fourth capacitors C4, and the upper and lower parts of the last third I-shaped component 13 are also connected to the upper and lower parts of the second I-shaped component 12 through another second capacitor C2 and another third capacitor C3, and are spaced apart from the previous third I-shaped component 13 and the second I-shaped component 12 by a second preset distance, so as to form a birdcage structure; the I-shaped structure 10 and the first I-shaped component 11 are enclosed to form a first visual field, and the I-shaped structure 10 and the second I-shaped component 12 are enclosed to form a second visual field, and the widths of the first visual field and the second visual field are both the first preset distance;

[0037] Among them, the first preset distance is greater than the second preset distance, the capacitance of the first capacitor C1 is greater than the capacitance of the fourth capacitor C4, and the capacitance of the first capacitor C1, the second capacitor C2, the third capacitor C3 and the fourth capacitor C4 are determined according to the first preset distance and the second preset distance so that the birdcage structure generates a uniform magnetic field.

[0038] In the above scheme, Figure 1It is a user-oriented planar schematic diagram. In actual testing, the MRI head function detection RF coil is a birdcage structure composed of an I-shaped structure 10, a first I-shaped component 11, a second I-shaped component 12, and a plurality of third I-shaped components 13 arranged in parallel. The third I-shaped components 13 are connected end to end through a fourth capacitor C4, the first I-shaped component 11 and the third I-shaped component 13 are connected end to end through a second capacitor C2 and a third capacitor C3, the second I-shaped component 12 and the third I-shaped component 13 are connected end to end through another second capacitor C2 and another third capacitor C3, and the first I-shaped component 11, the second I-shaped component 12 and the I-shaped structure 10 are connected end to end through the first capacitor C1. The I-shaped structure 10 and the first I-shaped component 11 enclose a first visual field, and the I-shaped structure 10 and the second I-shaped component 12 enclose a second visual field. The widths of the first visual field and the second visual field are both the first preset distance.

[0039] The utility model provides a radio frequency coil for detecting head function of magnetic resonance, so that the user to be detected can see objects through the gap between the two by controlling the spacing between the I-shaped structure 10 and the first I-shaped component 11 and the second I-shaped component 12, and the birdcage structure generates a uniform magnetic field by adjusting the capacitance of the plurality of first capacitors C1 and the capacitance of the plurality of second capacitors C2, thereby widening the field of view of the detection coil and solving the technical problem of the user easily generating an uncomfortable feeling of claustrophobia during detection in the prior art without changing the detection effect of the radio frequency coil.

[0040] It should be noted that the capacitances of the plurality of first capacitors C1 are equal, the capacitances of the plurality of second capacitors C2 are equal, the capacitances of the plurality of third capacitors C3 are equal, and the capacitances of the plurality of fourth capacitors C4 are equal.

[0041] The capacitance of the first capacitor C1, the second capacitor C2, the third capacitor C3 and the fourth capacitor C4 are determined according to the first preset distance and the second preset distance. This determination process is implemented by simulation software, and the implementation process is to determine the distance between each third I-type component 13, the distance between the first I-type component 11 and the adjacent third I-type component 13, the distance between the second I-type component 12 and the adjacent third I-type component 13, the width of the first visual field and the width of the second visual field. The above parameters are input into the magnetic field simulation software that has been modeled for simulation, and the capacitance of the first capacitor C1, the second capacitor C2, the third capacitor C3 and the fourth capacitor C4 are debugged one by one until the birdcage structure generates a uniform magnetic field, and then the specific capacitance of each capacitor is determined.

[0042] Optionally, the first preset distance is 78.6 mm and the second preset distance is 49 mm.

[0043] In an optional embodiment, the MRI head function detection RF coil also includes two second unidirectional conductive components D2, the anode of one second unidirectional conductive component D2 is connected to one end of the third I-shaped component 13 close to the first I-shaped component 11, and the cathode of one second unidirectional conductive component D2 is connected to the first I-shaped component 11 through a second capacitor C2; the anode of another second unidirectional conductive component D2 is connected to one end of the third I-shaped component 13 close to the second I-shaped component 12, and the cathode of the second unidirectional conductive component D2 is connected to the second I-shaped component 12 through another second capacitor C2.

[0044] In the above scheme, the second unidirectional conductive component D2 is provided, and cooperates with the second unidirectional conductive component D2 in each I-type component, thereby limiting the current flow direction of each coil, so that the magnetic field of the coil is in the same direction and almost equal in size each time, and the magnetic field distribution remains unchanged, thereby improving the overall stability of the RF coil for magnetic resonance head function detection.

[0045] Optionally, the second unidirectional conducting component D2 is a diode, and the first unidirectional conducting component is a diode.

[0046] Optionally, the first capacitor C1, the second capacitor C2, the third capacitor C3 and the fourth capacitor C4 are capacitors, which can be selected as needed.

[0047] In an optional embodiment, the I-shaped structure 10 and the first I-shaped component 11 enclose a first visible field of view, and the I-shaped structure 10 and the second I-shaped component 12 enclose a second visible field of view; the MRI head function detection radio frequency coil also includes a first visible window arranged in the first visible field of view, and a second visible window arranged in the second visible field of view.

[0048] In the above embodiment, by providing a visual window, it can be ensured that the user can widen the visual field through the visual window, thereby reducing the user's sense of claustrophobia.

[0049] Optionally, the first visible window and the second visible window are 87.5 mm long and 56 mm wide.

[0050] The utility model also proposes a radio frequency detection system, including the above-mentioned magnetic resonance head function detection radio frequency coil and a head-mounted receiving array coil, the head-mounted receiving array coil is fixed on a flexible member, and when the flexible member is worn on a human body, the head-mounted receiving array coil is arranged to fit the wearer's lower jaw.

[0051] The design of the flexible part can be worn by different patients, and the coil unit can be adaptively bent, so as to ensure that the coil can fit the patient's head closely and improve the imaging quality. At this time, the bending degree will not affect the resonant frequency of the coil, because the bending of the coil will not change the change in the self-inductance of the coil conductor loop, so that the fit between the user and the receiving array coil can be improved without changing the performance of the coil, thereby improving the detection quality and thus improving the imaging quality.

[0052] Since the above-mentioned radio frequency detection system is manufactured using a radio frequency coil for magnetic resonance head function detection, it includes all the solutions and beneficial effects of the radio frequency coil for magnetic resonance head function detection, which will not be described in detail here.

[0053] In the above embodiment, the parameters of the lumped elements on the coil can be adjusted to achieve resonance at Larmor frequencies corresponding to different magnetic resonance field strengths so as to be backward compatible with 3.0T magnetic resonance imaging systems or higher field magnetic resonance imaging systems.

[0054] Optionally, the flexible member is nylon stretch fabric, leather, etc., and the head-mounted receiving array coil can be fixed on the flexible member according to a printed circuit process or a liquid metal process.

[0055] Optionally, the head-mounted receiving array coil further includes a plurality of coils 21 arranged to overlap each other in pairs, and each coil transmits the received signal to the host computer through an independent channel.

[0056] Among them, the coils 21 that are arranged to overlap each other can achieve mutual decoupling between each coil, avoiding the influence of the magnetic fields between the coils 21 and causing inaccurate detection results, thereby optimizing the coil unit structure, and being able to achieve concentrated imaging of the motor sensory functional areas of the head to obtain high signal-to-noise ratio and higher resolution images.

[0057] Optionally, the number of coils 21 is 24, and the composed head-mounted receiving array coils are centrally symmetrically arranged.

[0058] By setting the above coil structure, feedback signals of multiple different positions of the human head after the radio frequency signal of the magnetic resonance head function detection radio frequency coil acts on the human head can be received through multiple channels, thereby realizing magnetic resonance imaging of the position corresponding to the magnetic resonance head function detection radio frequency coil.

[0059] Optionally, the head-mounted receiving array coil is 282 mm long and 107 mm wide, and the diameter of each coil is 40 mm.

[0060] Optionally, a first wearing portion 22 and a second wearing portion 23 are further provided on the flexible member, and the first wearing portion 22 and the second wearing portion 23 are provided based on a head-mounted receiving array coil.

[0061] Through the above settings, the position of the head-mounted receiving array coil can be better fixed.

[0062] Based on the above scheme, in order to verify the coil imaging performance, the 5.0T magnetic resonance imaging system of United Imaging was used as the test platform, and the head coil of the utility model was combined to carry out water film imaging test, human head scanning imaging test and commercial coil imaging performance comparison analysis, and analyze the imaging effect of the system. The experimental results prove that it is feasible and high-resolution brain function image data can be obtained.

[0063] In the description provided herein, a large number of specific details are described. However, it is understood that embodiments of the present invention can be practiced without these specific details. Similarly, in order to simplify the present invention and help understand one or more of the various aspects of the present invention, in the above description of the exemplary embodiments of the present invention, the various features of the embodiments of the present invention are sometimes grouped together into a single embodiment, figure, or description thereof. Among them, the claims that follow the specific embodiments are hereby expressly incorporated into the specific embodiments, wherein each claim itself serves as a separate embodiment of the present invention.

[0064] Those skilled in the art will appreciate that the modules in the devices in the embodiments may be adaptively changed and arranged in one or more devices different from the embodiments. The modules or units or components in the embodiments may be combined into one module or unit or component, and further may be divided into a plurality of submodules or subunits or subcomponents. Except that at least some of such features and / or processes or units are mutually exclusive.

[0065] It should be noted that the above embodiments illustrate the utility model rather than limit the utility model, and those skilled in the art may design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference symbol between brackets should not be constructed as a limitation on the claims. The word "comprising" does not exclude the existence of elements or steps not listed in the claims. The word "one" or "an" preceding an element does not exclude the existence of multiple such elements. The utility model can be implemented by means of hardware including several different elements and by means of appropriately programmed computers. In a unit claim that lists several devices, several of these devices may be embodied by the same hardware item. The use of the words first, second, and third, etc. does not indicate any order. These words can be interpreted as names. The steps in the above embodiments should not be understood as limitations on the order of execution unless otherwise specified.

Claims

1. A radio frequency coil for magnetic resonance head function detection, characterized in that: include: 2N T-shaped structures, a plurality of first capacitors, a plurality of second capacitors, a plurality of third capacitors, a plurality of fourth capacitors, N first unidirectional conductive members and an I-shaped structure, wherein every two T-shaped structures are connected by a first unidirectional conductive member to form an I-shaped assembly; the I-shaped assembly includes a first I-shaped assembly, a second I-shaped assembly and a plurality of third I-shaped assemblies; The first I-shaped component and the second I-shaped component are symmetrical based on the I-shaped structure and are respectively arranged at a first preset distance from the I-shaped structure. The upper part and the lower part of the I-shaped structure are respectively connected end to end with the first I-shaped component and the second I-shaped component through the first capacitor. N is a natural number greater than 1; The upper part and the lower part of the third I-shaped component are connected to the upper part and the lower part of the first I-shaped component through the second capacitor and the third capacitor respectively, and are arranged at a second preset distance from the first I-shaped component; Sequentially connect the upper and lower parts of the next third I-shaped component to the upper and lower parts of the previous third I-shaped component through two fourth capacitors, respectively, and set them at a second preset distance from the previous third I-shaped component; until the upper and lower parts of the last third I-shaped component are connected to the previous third I-shaped component through two fourth capacitors, respectively, and the upper and lower parts of the last third I-shaped component are also connected to the upper and lower parts of the second I-shaped component through another second capacitor and another third capacitor, and set them at a second preset distance from the previous third I-shaped component and the second I-shaped component, so as to form a birdcage structure; the I-shaped structure and the first I-shaped component enclose a first visual field, and the I-shaped structure and the second I-shaped component enclose a second visual field, and the widths of the first visual field and the second visual field are both the first preset distance; Among them, the first preset distance is greater than the second preset distance, the capacitance of the first capacitor is greater than the capacitance of the fourth capacitor, and the capacitance of the first capacitor, the second capacitor, the third capacitor and the fourth capacitor are determined according to the first preset distance and the second preset distance, so that the birdcage structure generates a uniform magnetic field.

2. The MRI head function detection radio frequency coil according to claim 1, characterized in that: The first preset distance is 78.6 mm, and the second preset distance is 49 mm.

3. The MRI head function detection radio frequency coil according to claim 1, characterized in that: The MRI head function detection RF coil also includes two second unidirectional conductive components, wherein the anode of one of the second unidirectional conductive components is connected to one end of the third I-shaped component close to the first I-shaped component, and the cathode of one of the second unidirectional conductive components is connected to the first I-shaped component through a second capacitor; the anode of another of the second unidirectional conductive components is connected to one end of the third I-shaped component close to the second I-shaped component, and the cathode of another of the second unidirectional conductive components is connected to the second I-shaped component through the second capacitor.

4. The MRI head function detection radio frequency coil according to claim 1, characterized in that: The I-shaped structure and the first I-shaped component form a first visual field, and the I-shaped structure and the second I-shaped component form a second visual field; the magnetic resonance head function detection radio frequency coil also includes a first visual window arranged in the first visual field, and a second visual window arranged in the second visual field.

5. The MRI head function detection radio frequency coil according to claim 4, characterized in that: The first visible window and the second visible window are 87.5 mm long and 56 mm wide.

6. A radio frequency detection system, characterized in that: It comprises a magnetic resonance head function detection radio frequency coil and a head-mounted receiving array coil as described in any one of claims 1 to 5, wherein the head-mounted receiving array coil is fixed on a flexible member, and when the flexible member is worn on a human body, the head-mounted receiving array coil is arranged to fit the wearer's lower jaw.

7. The radio frequency detection system according to claim 6, characterized in that: The head-mounted receiving array coil also includes a plurality of coils that are arranged to overlap each other in pairs, and each coil transmits the received signal to the host computer through an independent channel.

8. The radio frequency detection system according to claim 6, characterized in that: The number of the coils is 24, and the head-mounted receiving array coil composed of the 24 coils is centrally symmetrically arranged.

9. The radio frequency detection system according to claim 6, characterized in that: The head-mounted receiving array coil is 282 mm long and 107 mm wide, and the diameter of each coil is 40 mm.

10. The radio frequency detection system according to claim 6, characterized in that: The flexible member is also provided with a first wearing portion and a second wearing portion, and the first wearing portion and the second wearing portion are provided based on a head-mounted receiving array coil.

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