KR20180045583A - Dipole antenna for magnetic resonance imaging, radio frequency coil assembly, and magnetic resonance imaging system - Google Patents

Abstract

The present invention relates to a dipole antenna for magnetic resonance imaging which can be tightly attached to a human body, an RF coil assembly, and a magnetic resonance imaging system including the RF assembly. The dipole antenna for magnetic resonance imaging is composed of two antennas composed of a stick portion and an annular head portion formed at the end of the stick portion, wherein the two spaced antennas are linearly arranged and the annular head portions are disposed at both ends.

Description

[0002] Dipole antennas for magnetic resonance imaging, RF coil assemblies, and magnetic resonance imaging systems

The present invention relates to a dipole antenna for a magnetic resonance imaging, an RF coil assembly including the dipole antenna, and a magnetic resonance imaging system including the RF coil assembly.

In general, magnetic resonance imaging (MRI) is a method of generating nuclear magnetic resonance in a body's proton (hydrogen nucleus) using a radiofrequency pulse, which is a non-harmful magnetic field and non-ionizing radiation, And medical images that image physicochemical properties.

The MRI apparatus of the conventional surface coil antenna structure has a plurality of surface coils each having a closed loop having a rectangular shape and being attached at regular intervals to the outer surface of the acrylic cylinder in the form of wrapping the object.

A magnetic field is formed when a current is applied to a plurality of surface coils, and a magnetic field formed in each of the plurality of surface coils penetrates the object to generate magnetic resonance image data.

However, in the MRI apparatus of the conventional surface coil antenna structure, when the surface coil is arranged in an annular shape, interference occurs between the plurality of coils. Therefore, there is a limit to insert a decoupling capacitor on the coil wire.

This decoupling capacitor induces resonance to induce the maximum current to flow through the coil conductor and reduce the interference between the plurality of coils, but the coil has high sensitivity only in the vicinity of the coil.

The signals input to the respective channels of the plurality of coils are input with different phases, for example, 45 degrees, to form circularly polarized, and coaxial cables for transmitting and receiving the generated magnetic resonance image data A matching circuit with an impedance of 50 shall be inserted.

In order to overcome the above-mentioned problem caused by a plurality of surface coils having closed circuits, a magnetic resonance imaging apparatus having a dipole antenna structure has been devised.

FIG. 3 is a schematic view showing an application of a dipole antenna included in a conventional RF coil assembly. FIG. 4 is a schematic diagram (a) and a principle diagram (b) of a conventional dipole antenna, Antennas 1-1 and 1-2, and a coaxial cable 3. [

The operation of the MRI apparatus of the dipole antenna structure according to the related art will be described with reference to FIG.

The magnetic resonance imaging apparatus of the dipole antenna structure according to the related art does not form a closed circuit like the magnetic resonance imaging apparatus of the surface coil antenna structure and the coaxial cable 3 is inserted between the dipole antennas 1-1 and 1-2, The signal line and the grounding line are connected to each other.

As shown in FIG. 4 (b), the dipole antennas 1-1 and 1-2 form a magnetic field rotating around the metal rod and electromagnetic waves are radiated in four directions perpendicular to the direction of the metal rod and the magnetic field .

Although the electromagnetic waves radiated through the dipole antennas 1-1 and 1-2 have high sensitivity to a region of interest far away from the antenna and thus have a greater depth of penetration than surface coils that do not emit electromagnetic waves, The length of the dipole antenna must be at least 50 cm in the 7T MRI, which is a conventional MRI apparatus having the dipole antenna. However, the dipole antenna has to be positioned in the longitudinal direction as shown in FIG. 3, There is a limitation that it is difficult for the head to be located at the center of the antenna when a circular array structure is used to measure the head image data.

Korean Patent Publication No. 10-2015-0033440

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art,

And it is an object of the present invention to provide a dipole antenna of a type capable of solving the problem of the length of a dipole antenna.

It is another object of the present invention to provide a dipole antenna which can be brought into close contact with a human body.

Another object of the present invention is to provide an RF coil assembly including an RF antenna array in which two or more dipole antennas are arranged side by side.

It is another object of the present invention to provide a magnetic resonance imaging system including the RF coil assembly.

According to the present invention,

A dipole antenna for a magnetic resonance imaging system,

Wherein the two antennas are arranged linearly spaced apart from each other and the annular head portion is disposed at both ends of the magnetic resonance imaging system A dipole antenna is provided.

In addition,

And an RF antenna array including two or more dipole antennas of the present invention arranged and fixed in parallel.

In addition,

In a magnetic resonance imaging system,

An RF coil assembly comprising at least two dipole antennas according to the present invention,

An RF transmission mode for applying an electric signal to the RF coil assembly so that a main magnetic field is formed in the space formed by the RF coil assembly and an RF transmission mode for switching an RF reception mode for receiving a magnetic resonance signal from the object placed in the formed main magnetic field. A coil control section, and

And an image processor for generating a magnetic resonance image of the subject based on the magnetic resonance signal received from the subject.

The dipole antenna of the present invention has an annular head portion at both ends, thereby providing an effect of reducing the length of the dipole antenna.

Further, the dipole antenna of the present invention can be arranged in various forms by eliminating the length problem, and it is possible to arrange the dipole antenna in a form to be in close contact with the human body, thereby providing an image with excellent resolution.

Further, since the RF coil assembly of the present invention has a structure including two or more dipole antennas, it can be arranged in various forms, and it is possible to arrange the RF coil assembly in such a manner that it is in close contact with a human body. To provide images.

Also, since the magnetic resonance imaging system of the present invention includes the RF coil assembly, it is possible to provide an image having excellent resolution.

1 and 2 are views illustrating a configuration of a magnetic resonance imaging system according to an embodiment of the present invention.
3 is a view schematically showing an application form of a conventional RF coil assembly and a dipole antenna included therein.
Fig. 4 is a schematic diagram (a) and a principle diagram (b) of a conventional dipole antenna.
5 is a view showing various forms of the dipole antenna of the present invention.
6 is a view showing a bent shape of the annular head portion of the dipole antenna of the present invention.
7 to 10 are views showing various forms of the RF coil assembly of the present invention.
11 is a view illustrating an example of a human body application of the RF coil assembly of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail since they would unnecessarily obscure the gist of the present invention.

The following description and drawings illustrate specific embodiments in order that those skilled in the art can readily implement the described apparatus and method. Other embodiments may include other variations, both structurally and logically. Unless explicitly required, individual components and functions may be selected generally, and the order of the processes may vary. Portions and features of some embodiments may be included in other embodiments or may be replaced by other embodiments.

In the dipole antenna for a magnetic resonance imaging system, as illustrated in Figs. 5 and 6,

And two antennas constituted by the stick portions 11 and 12 and the annular head portions 11-1 and 12-1 formed at the ends of the stick portions 11 and 12. The two antennas are arranged linearly spaced apart from each other, And the head portions (11-1, 12-1) are disposed at both ends of the dipole antenna (10).

In a magnetic resonance imaging system, a conventional dipole antenna has a disadvantage in that it is difficult to apply to various parts of the human body in close contact with the human body because of its long length.

Disclosure of the Invention The present inventors have made intensive efforts to solve the above problems, and discovered that the problem of the length can be solved by forming the annular head portion at the end of the dipole antenna, thereby completing the present invention.

Specifically, the dipole antenna of the present invention provides an effect of reducing the length by approximately 10% to 50% as compared with the conventional dipole antenna.

The dipole antenna 10 forms an RF antenna array in which two or more are arranged and fixed, and the RF antenna array is included in the RF coil assembly and used in a magnetic resonance imaging system.

1 and 2, the RF coil assembly 130 is configured to detect the body part of the subject in the magnetic resonance imaging system 100, for example, And is installed in a part of the body of the subject to take a magnetic resonance image of a local part such as a head, a chest, a leg, and the like. The RF coil assembly 130 is a separate independent device provided outside the circular housing 190, and is a device that is movable to be positioned in a part of the body of a subject desired to be photographed with magnetic resonance images. Although a planar RF coil assembly 130 is shown in FIG. 1 and a circular RF coil assembly 130 is shown in FIG. 2 different from FIG. 1, the RF coil assembly 130 in FIGS. 1 and 2 ) Are the same in function and role.

The magnetic resonance imaging system 100 will be described in detail below.

In the dipole antenna 10 of the present invention, the annular head portions 11-1 and 12-1 may be formed in various shapes such as circular, elliptical, or polygonal shapes as shown in FIG.

The two annular head portions 11-1 and 12-1 included in the dipole antenna 10 may be provided in the same shape or may be provided in different shapes.

The dipole antenna of the present invention can be made of a flexible material whose shape can be modified, as shown in Fig.

The flexible material is not particularly limited, and materials known in the art can be used. For example, copper, a copper alloy, or the like can be used.

In the dipole antenna 10 of the present invention, the signal line of the coaxial cable is connected to one of the two stick portions 11 and 12 included in the dipole antenna, and the ground line of the coaxial cable is connected to the other one of the stick portions .

In addition,

The present invention relates to an RF coil assembly 130 comprising two or more dipole antennas 10 of the present invention, which are arranged side by side and fixed, as illustrated in FIGS. 7 to 10.

The two or more dipole antennas 10 arranged side by side may have the same type of annular head portion or may have another type of annular head portion.

The two annular head portions included in each of the dipole antennas included in the above may be the same or different.

The RF antenna array may further include a polymer plate 20 or a polymer cylindrical tube 30 that fixes two or more dipole antennas 10.

The material of the plate or the cylindrical tube is not particularly limited, and materials known in this field can be used. For example, an acrylic resin or the like can be used.

The plate may be planar as illustrated in Fig. 8 or curved as illustrated in Fig. The shape of the curved surface is not particularly limited, and a shape that can be adhered to a human body can be preferably used.

Some or all of the stick portions 11 and 12 of the dipole antennas are fixed on the polymer plate 20 as illustrated in Figs. 7 to 9, and the annular head portions 11-1 (12-1) Can be fixed so as to be exposed to the outside of the polymer plate.

Of course, all of the dipole antennas, including the annular head portion, may be fixed on the polymer plate 20.

The annular head portions (11-1; 12-1) exposed to the outside of the polymer plate can be bent in the direction of the subject according to the shape of the subject. When the dipole antenna is provided closely to the human body as described above, a uniform and high resolution image can be obtained.

The RF coil assembly formed by the polymer plate can be preferably used for photographing various parts of the human body such as a chest, a thigh, a joint, and the like.

10, a part or the whole of the stick portion of the dipole antennas is fixed to the outer circumferential surface of the polymer cylindrical tubular body 30 in a direction parallel to the center axis, and the annular head portions 11-1 -1) may be fixed so as to be exposed to the outside of the cylindrical tubular body.

Of course, all the dipole antennas including the annular head portion may be fixed in the direction parallel to the center axis in the outer peripheral surface of the cylindrical tube body.

The annular head portions (11-1; 12-1) exposed out of the cylindrical tubular body (30) can be bent in the direction of the subject according to the shape of the subject. When the dipole antenna is provided closely to the human body as described above, a uniform and high resolution image can be obtained.

The RF coil assembly formed by the cylindrical tubular body can be preferably used for photographing the head.

As described above with reference to FIGS. 7 through 10, the RF coil assembly 130 of the present invention may be formed in a planar shape, a cylindrical shape, or any other shape.

In the RF coil assembly of the present invention, the signal line of the coaxial cable may be connected to one of the two stick portions included in each of the dipole antennas, and the ground line of the coaxial cable may be connected to the other one of the stick portions 4 (a)).

In addition,

In a magnetic resonance imaging system, as illustrated in Figures 1 and 2,

The RF coil assembly 130 includes two or more dipole antennas 10 according to the present invention,

An RF transmission mode for applying an electric signal to the RF coil assembly so that a main magnetic field is formed in the space formed by the RF coil assembly and an RF transmission mode for switching an RF reception mode for receiving a magnetic resonance signal from the object placed in the formed main magnetic field. Coil control unit 110, and

And an image processing unit (120) for generating a magnetic resonance image of the subject based on the magnetic resonance signal received from the subject.

The above-described contents of the dipole antenna and RF coil assembly of the present invention are directly applied to the magnetic resonance imaging system 100 of the present invention. Therefore, description of overlapping portions is omitted.

Hereinafter, general configurations included in the magnetic resonance imaging system 100 of the present invention will be described in detail. The following description is intended to illustrate a general configuration of a magnetic resonance imaging system, and the configurations illustrated below may be replaced with known techniques.

1 and 2 are block diagrams of a magnetic resonance imaging system 100 according to an embodiment of the present invention. 1 and 2, only the shape of the RF coil assembly 130 differs from that of the planar or circular shape, and the other structures are the same. Therefore, the description will be made in conjunction with FIG. 1 and FIG.

Referring to FIGS. 1 and 2, a magnetic resonance imaging system 100 of the present embodiment includes a computing device 100 and a circular housing 190.

The circular housing 190 includes a volumetric RF coil device 140 for transmission only, an oblique magnetic field coil 150, and a main magnet 160 in this order from the inner side to the outer side. The subject moves to the hollow 190a of the circular housing 190 in a lying state on the table 170, and then the magnetic resonance image is photographed.

A transmission type volume RF coil device 140, an oblique magnetic field coil 150 and a main magnet 160 constituting a circular housing 190 in the magnetic resonance imaging system 100 are connected to the computing device 100 and driven And controlled. The computing device 100 may also be connected to a console (not shown) in which a magnetic resonance image of the photographed body is displayed or a user's operation signal is input.

The volume RF coil device 140 dedicated for transmission in the MRI system 100 may be a flat RF coil assembly 130 of FIG. 1 or a circular RF coil assembly 130 of FIG. 2, And may be independently driven and controlled by the RF coil control unit 110 of the computing device 100. [

The main magnet 160 generates a magnetic field for magnetizing atomic nuclei such as hydrogen, phosphorus, sodium, carbon and the like, which cause magnetic resonance phenomenon among the elements distributed in the human body. The main magnet 160 may be a superconducting electromagnet or a permanent magnet.

The oblique magnetic field coil 150 is a coil for generating a spatially linear gradient magnetic field in order to image a magnetic resonance image. Normally, the magnetic field coil 150 has three An oblique magnetic field coil is used. The gradient magnetic field coil 150 functions to spatially control the rotation frequency and the phase of the magnetization vector when the magnetization vector rotates in the transverse plane, so that the magnetic resonance image signal is expressed in the spatial frequency domain, that is, the k-domain.

In order to generate a magnetic resonance image signal, a magnetization vector must be arranged in a transverse plane. To do this, a volume type RF coil device 140 and an RF coil assembly 130, which generate an RF magnetic field having a center frequency of a Larmor frequency, Do. The volume type RF coil device 140 and the RF coil assembly 130 to which the RF current in the Larmo frequency band is applied form a rotating magnetic field rotating at the Larmo frequency. When the resonance of the magnetization vector, that is, the nuclear magnetic resonance is caused by the rotating magnetic field, the magnetization vector is aligned to the transverse plane. Once the magnetization vector is aligned in the transverse plane, the magnetization vector rotating in the transverse plane at the Larmo frequency generates an electromotive force in the RF coil assembly 140 and RF coil assembly 130 by the Faraday's law. After amplifying the electromotive force signal, that is, the received RF signal by a high frequency amplifier and then demodulating it with a sinusoidal wave of a lamb wave frequency, a magnetic resonance signal of a base band can be obtained. The magnetic resonance signal of the baseband is transmitted to the computing device 100, and after being subjected to a process such as quantization by the image processing unit 120, a magnetic resonance image is generated.

As described above, a general principle of generating a magnetic resonance image in the MRI system 100 is briefly described.

A more detailed description of the process of generating a magnetic resonance image will be omitted since it will be obvious to those skilled in the art.

The volume RF coil device 140 provided in the circular housing 190 in the magnetic resonance imaging system 100 can be used to take a magnetic resonance image of the whole body of the subject. Alternatively, the RF coil assembly 130 installed in a body part of the subject may be used for photographing a magnetic resonance image of a part of the body of the subject, for example, a head, a chest, a leg or the like. The RF coil assembly 130 is a separate independent device provided outside the circular housing 190, and is a device that is movable to be positioned in a part of the body of a subject desired to be photographed with magnetic resonance images.

1, a planar RF coil assembly 130 is shown, and a circular RF coil assembly 130, which is different from FIG. 1, is shown in FIG. 2, but in FIG. 1 and FIG. 2 The function and role of the RF coil assembly 130 is the same.

On the other hand, the resonance frequency of the RF coil optimized for the MRI system 100 varies depending on the operating frequency of the MRI system 100. The operating frequency of 127.74 MHz when the magnetic resonance imaging system 100 is operated with 3T (tesla), the operating frequency of 200 MHz when operating with 4.7T, the operating frequency of 300 MHz when operating with 7T, and 9.4T If you have an operating frequency of 400 MHz.

In the foregoing, a dipole antenna of the present invention, an RF coil assembly including the dipole antenna, and a magnetic resonance imaging system including the RF coil assembly have been described with respect to a characteristic portion in comparison with the conventional technique. Therefore, the configurations other than the characteristic parts described above can be applied to the known techniques as they are.

Although the present invention has been described in connection with the above-mentioned preferred embodiments, it is possible to make various modifications and variations without departing from the spirit and scope of the invention. Accordingly, it is intended that the appended claims cover all such modifications and variations as fall within the true spirit of the invention.

10: dipole antenna 11, 12:
11-1, 12-1: annular head portion
20: Polymer plate 30: Polymer cylindrical tube
100: magnetic resonance imaging system 110: RF coil controller
120: image processor 130: RF coil assembly
140: volume type RF coil device 150: gradient magnetic field coil
160: main magnet 170: table
190: round housing 190a: hollow
200: RF coil assembly

Claims (22)

A dipole antenna for a magnetic resonance imaging system,
Wherein the two antennas are arranged linearly spaced apart from each other and the annular head portion is disposed at both ends of the magnetic resonance imaging system Dipole Antenna for. The method according to claim 1,
Wherein the annular head portion has a circular, elliptical, or polygonal shape. The method of claim 2,
Wherein the two annular head portions included in the dipole antenna are provided in the same shape or in different shapes. The method according to claim 1,
Wherein the dipole antennas are made of a flexible material that is deformable in shape. The RF coil assembly according to claim 1, wherein at least two dipole antennas are arranged side by side and fixed. The method of claim 5,
Wherein the RF antenna array further comprises a polymer plate or polymeric tubular body to secure two or more dipole antennas. The method of claim 6,
Wherein the plate is planar or curved. The method of claim 6,
Wherein some or all of the stick portions of the dipole antennas are fixed on the polymer plate and the annular head portions are fixed so as to be exposed out of the polymer plate. The method of claim 8,
Wherein the annular head portions are bent toward the subject in accordance with the shape of the subject. The method of claim 6,
Wherein part or all of the stick portions of the dipole antennas are fixed to the outer circumferential surface of the polymer cylindrical tubular body in a direction parallel to the central axis and the annular head portions are fixed so as to be exposed outside the cylindrical tubular body. The method of claim 10,
Wherein the annular head portions are bent toward the subject in accordance with the shape of the subject. The method of claim 5,
Wherein a signal line of a coaxial cable is connected to one of the two stick portions included in each of the dipole antennas and a ground line of a coaxial cable is connected to the other one of the stick portions. The method of claim 5,
Wherein the annular head portion of the dipole antenna is in the form of a circular, elliptical, or polygonal shape. 14. The method of claim 13,
Wherein the two annular head portions included in the dipole antenna are provided in the same shape or in different shapes. The method of claim 5,
Wherein the dipole antennas are made of a flexible material that is deformable in shape. In a magnetic resonance imaging system,
An RF coil assembly, characterized in that at least two dipole antennas of claim 1 are arranged side by side and comprise a fixed RF antenna array,
An RF transmission mode for applying an electric signal to the RF coil assembly so that a main magnetic field is formed in the space formed by the RF coil assembly and an RF transmission mode for switching an RF reception mode for receiving a magnetic resonance signal from the object placed in the formed main magnetic field. A coil control section, and
And an image processor for generating a magnetic resonance image for the subject based on the magnetic resonance signal received from the subject. 18. The method of claim 16,
Wherein part or all of the stick portions of the dipole antennas in the RF coil assembly are fixed on the polymer plate and the annular head portions are fixed so as to be exposed out of the polymer plate. 18. The method of claim 17,
Wherein the annular head portions are bent toward the subject in accordance with the shape of the subject. 18. The method of claim 16,
Wherein part or all of the stick portions of the dipole antennas in the RF coil assembly are fixed to the outer circumferential surface of the polymer cylindrical tubular body in a direction parallel to the central axis and the annular head portions are fixed to be exposed to the outside of the polymer plate system. The method of claim 19,
Wherein the annular head portions are bent toward the subject in accordance with the shape of the subject. 18. The method of claim 16,
Wherein the annular head portion of the dipole antenna is of a circular, elliptical, or polygonal shape. 23. The method of claim 21,
Wherein the two annular heads included in the dipole antenna are provided in the same shape or in different shapes.

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