WO2017057820A1

WO2017057820A1 - Multi-channel rf coil array for magnetic resonance imaging device

Info

Publication number: WO2017057820A1
Application number: PCT/KR2016/004957
Authority: WO
Inventors: 서증훈; 한상덕; 김경남; 류연철; 정준영
Original assignee: (의료)길의료재단; 가천대학교 산학협력단
Priority date: 2015-10-02
Filing date: 2016-05-12
Publication date: 2017-04-06
Also published as: KR101676192B1

Abstract

The present invention relates to a multi-channel RF coil array for a magnetic resonance imaging device and, more particularly, to a multi-channel transmission-dedicated RF coil using multiple circular polarized (CP) modes in a super-high-frequency magnetic resonance imaging device. The present invention provides a multi-channel RF coil array for a magnetic resonance imaging device comprising as many as L coil elements that surround the subject circularly, wherein the L coil elements are classified into a plurality of coil groups comprising a plurality of coil elements, a plurality of current phase values, which increase by an integer multiple of 360°/L, are applied to the plurality of coil elements belonging to each coil group, and the plurality of current phase values, which are applied to each coil group, are applied independently of a plurality of current phase values applied to a different coil group. The present invention is advantageous in that a plurality of current phase values, which are applied to each of the first coil group and the second coil group, can be applied independently of each other, making it possible to form a uniform magnetic field.

Description

Multichannel RF Coil Array for Magnetic Resonance Imaging

The present invention relates to a multi-channel RF coil array for a magnetic resonance imaging apparatus, and more particularly to a multi-channel transmission-only RF coil using a plurality of CP (circular polarized) mode in the ultra-high frequency magnetic resonance imaging apparatus.

Magnetic resonance imaging (MRI) refers to a medical device that displays a distribution of hydrogen nuclei in the body by applying high frequency harmless to the human body.

This is a technology that measures the magnetic properties of the material constituting the human body and reconstructs and images through a computer.

The principle of MRI works in a way that is well known.

Obviously, in order to obtain a clear image of an inspection target by using an MRI device, the coil has a role such as applying a good magnetic field to the inspection target or receiving a good signal from the hydrogen nucleus. Above all, it is important.

Applying uniformly inside the subject may be the best way to obtain a clear image.

On the other hand, the conventional general multi-channel transmission and reception coil is mainly used to improve the uniformity of the transmission-only field in the form of a coil applied in the ultra-high magnetic field MR system.

1 is a circuit to which a multi-channel transmission / reception coil 40 is applied using a single amplifier 10 in a conventional ultra-high frequency magnetic resonance imaging system.

When the multi-channel transmitting / receiving coil 40 using the conventional single amplifier is configured with eight channels, for example, each coil is 0 degrees 45 degrees from the first channel to the eighth channel so that each coil has a 45 degree phase difference sequentially. RF sources may be applied to have degrees, 90 degrees, 135 degrees, 180 degrees, 225 degrees, 270 degrees, and 315 degrees, respectively, which are signal processed through the phase converter 30 and the driver 20.

The multi-channel transmitting / receiving coil 40 to which the conventional single amplifier 10 is applied has a problem in that uniformity of a transmission-only field is reduced in the form of a coil applied in an ultra-high magnetic field MR system.

Korean Patent No. 805,600, which is a prior art, relates to a method and an apparatus for improving magnetic resonance image uniformity using time division multiple high frequency pulses.

Korean Patent No. 805,600 relates to a technique for time-dividing a high frequency pulse waveform to a human body in order to improve uniformity of magnetic resonance images.

This is to overcome the problem that the uniformity of the image is reduced when the human body is photographed due to the short wavelength of electromagnetic waves in the high magnetic field magnetic resonance imaging system of 3.0 Tesla or higher. It is a technique which suppresses that and improves the spatial RBS degree of the high frequency magnetic field applied to a human body.

This includes generating a high frequency pulse as a time division multiple pulse and applying a time division high frequency pulse to the high frequency coil, which also has a problem in that uniformity of a transmission field is not constant.

(Patent Document 1) KR805600 B1

(Patent Document 2) US7091721 B2

(Patent Document 3) US6608480 B1

Accordingly, the present invention has been made to overcome the problems of the prior art as described above, in order to increase the uniformity of the transmission field in the ultra-high magnetic resonance imaging system to have a different mode phase in odd and even channels A multichannel RF coil array for a resonance imaging apparatus.

The present invention for solving the above problems is a multi-channel RF coil array for a magnetic resonance imaging apparatus, the multi-channel RF coil array includes L coil elements surrounding the object under test circularly, the L coil The elements are divided into a plurality of coil groups composed of a plurality of coil elements, and a plurality of current phase values increasing by an integer multiple of 360 ° / L are applied to the plurality of coil elements belonging to each coil group. The plurality of current phase values applied to the coil group provides a multi-channel RF coil array for a magnetic resonance imaging apparatus that is independently applied to the plurality of current phase values applied to another coil group.

In addition, the multi-channel RF coil array includes 2 x N coil elements surrounding the object under test circularly, the 2 x N coil elements are arranged in an odd number along the circumferential direction of the multi-channel RF coil array A first coil group composed of N coil elements, and a second coil group composed of N coil elements disposed in even-numbered positions along the circumferential direction, wherein the first coil group and the second coil group Each coil element is supplied with currents according to any one of 2xN branch current phase (CP) modes defined by the CP mode equation below. CP (M, n) = {360 ° In the formula / (2 × N)} × M × (n-1), N is a natural number equal to or greater than 4, M is a number specifying a mode, and an integer other than 0 between -N and N, and n in each group To indicate the placement order of each coil element. Is a natural number for the MRI apparatus from between 1 N and a channel RF coil arrays.

The present invention as described above has the following effects.

Since a plurality of current phase values applied to each of the first coil group and the second coil group may be independently applied to each other, a uniform magnetic field may be formed.

1 is a conceptual diagram of transmitting and receiving of an RF coil to which a single amplifier according to the prior art is applied, and FIG. 2 is a perspective view of an 8-channel RF coil array according to the prior art.

3 is a multi-channel RF coil array for an MRI device having 8 channels according to a first embodiment of the present invention, in which a CP + 2 mode is applied to a first coil group and a CP-1 to a second coil group. A perspective view of a multi-channel RF coil array for magnetic resonance imaging apparatus to which a mode is applied.

4 is a multi-channel RF coil array for an MRI device having 8 channels according to a second embodiment of the present invention, in which a CP + 1 mode is applied to a first coil group and a CP-4 is applied to a second coil group. A perspective view of a multi-channel RF coil array for magnetic resonance imaging apparatus to which a mode is applied.

5 is a multi-channel RF coil array for a magnetic resonance imaging apparatus consisting of 16 channels according to a third embodiment of the present invention, in which a CP + 3 mode is applied to a first coil group and a CP-7 is applied to a second coil group. A perspective view of a multi-channel RF coil array for magnetic resonance imaging apparatus to which a mode is applied.

6 is a multi-channel RF coil array for a magnetic resonance imaging apparatus consisting of 16 channels according to a fourth embodiment of the present invention, in which a CP + 2 mode is applied to a first coil group and a CP-1 to a second coil group. A perspective view of a multi-channel RF coil array for magnetic resonance imaging apparatus to which a mode is applied.

Hereinafter, with reference to the accompanying drawings will be described in detail.

In this process, the thickness of the lines or the size of the components shown in the drawings may be exaggerated for clarity and convenience of description. In addition, terms to be described later are terms defined in consideration of functions in the present invention, which may vary according to the intention or convention of a user or an operator. Therefore, definitions of these terms should be described based on the contents throughout the specification.

The multi-channel RF coil array to be described below includes 2 x N coil elements that circularly surround the object under test.

The 2 × N coil elements have a first coil group consisting of N coil elements arranged in an odd number along the circumferential direction of the multichannel RF coil array.

It also includes a second coil group consisting of N coil elements disposed in even-numbered positions along the circumferential direction.

The coil elements of each of the first coil group and the second coil group are applied with currents according to any one of the CP modes of 2 × N branch current phase (CP) modes defined by the following CP mode equation.

CP (M, n) = {360 ° / (2 × N)} × M × (n-1)

In the above formula, N is a natural number equal to or greater than 4, M is a number specifying a mode, an integer other than 0 between -N and N, and n is a natural number between 1 and N indicating the arrangement order of each coil element in each group. Is preferably.

This will be described in more detail as follows.

Table 1

Table 1 shows the arrangement order in the coil group and the phase value of the CP mode according to the 8-channel multi-channel RF coil array for a magnetic resonance imaging apparatus according to an embodiment of the present invention.

The multi-channel RF coil array for the magnetic resonance imaging apparatus will be described as follows.

The odd channel group as the first coil group has the first channel, the third channel, the fifth channel, and the seventh channel. The even channel group as the second coil group has the second channel, the fourth channel, the sixth channel, and the first channel. It has 8 channels.

In this case, the n value means an arrangement order of channels in each coil group.

For example, the first channel, which is the first channel of the odd channel group, which is the first coil group, has an n value of 1, the second channel, the third channel, has an n value of 2, and the third channel, the fifth channel, has a n value of 3. The seventh channel, which is the fourth channel, has n value of 4.

The same applies to the even channel group which is the second coil group.

As shown in Table 1, applicable CP modes in this case are CP + 1, CP + 2, CP + 3, CP + 4 modes and CP-1, CP-2, CP-3, CP-4 modes. . That is, each of the first and second coil groups includes CP + 1 mode, CP + 2 mode, CP + 3 mode, CP + 4 mode, CP-1 mode, CP-2 mode, CP-3 mode and CP-4 mode. Any one of the modes may be applied.

In each CP mode, each time the value of n increases, the phase increases or decreases by n times.

Referring to [Table 1], when CP + 2 mode is applied to an odd channel that is a first coil group as shown in FIG. 3, for example, a zero degree phase value is applied to a first channel having n value of 1, and an n value. A +90 degree phase value is applied to the third channel of 2, a +180 degree phase value is applied to a fifth channel of n value 3, and a +270 degree phase value is applied to a seventh channel of n value 4 do.

On the other hand, when CP-1 mode is applied to an even channel, which is a second coil group, for example, a zero degree phase value is applied to a second channel having an n value of 1, and a -45 degree is applied to a fourth channel having an n value of 2. A phase value is applied, a -90 degree phase value is applied to the sixth channel having an n value of 3, and a -135 degree phase value is applied to an eighth channel having an n value of 4.

As such, a plurality of current phase values applied to each of the first coil group and the second coil group may be independently applied to each other, thereby making it possible to form a uniform magnetic field.

Referring to Table 1, when CP + 1 mode is applied to an odd channel that is the first coil group as shown in FIG. 4, a zero degree phase value is applied to a first channel having n value of 1, and an n value. A +45 degree phase value is applied to the third channel of 2, a +90 degree phase value is applied to the fifth channel of n value 3, and a +135 degree phase value is applied to the seventh channel of n value 4 do.

On the other hand, when the CP-4 mode is applied to an even channel, which is a second coil group, for example, a zero degree phase value is applied to a second channel having an n value of 1, and a -180 degree is applied to a fourth channel having an n value of 2. A phase value is applied, a -360 degree phase value is applied to the sixth channel having an n value of 3, and a -540 degree phase value is applied to an eighth channel having an n value of 4.

It should be understood that other CP modes may be independently applied to each coil group by the same principle.

Next, the multi-channel RF coil array for the magnetic resonance imaging apparatus will be described with a total of 16 channels as follows.

TABLE 2

Table 2 shows the arrangement order in the coil group and the phase value of the CP mode according to the 16-channel multi-channel RF coil array for a magnetic resonance imaging apparatus according to another embodiment of the present invention.

The odd channel group, which is the first coil group, has the first channel, the third channel, the fifth channel, the seventh channel, the ninth channel, the eleventh channel, the thirteenth channel, and the fifteenth channel. The channel group has a second channel, a fourth channel, a sixth channel, an eighth channel, a tenth channel, a twelfth channel, a fourteenth channel, and a sixteenth channel.

For example, the first channel, which is the first channel of the odd channel group, which is the first coil group, has an n value of 1, the second channel, the third channel, has an n value of 2, and the third channel, the fifth channel, has a n value of 3. The seventh channel, the fourth channel, has an n value of 4. The ninth channel, the fifth channel, has an n value of 5. The eleventh channel, the sixth channel, has an n value of 6. n value is 7 and the 15th channel which is the 8th channel has n value of 8.

The same applies to the even channel group which is the second coil group.

In this case, the applicable CP modes are CP + 1, CP + 2, CP + 3, CP + 4, CP + 5, CP + 6, CP + 7, CP + 8 modes and CP-1, CP-2, CP- 3, CP-4, CP-5, CP-6, CP-7, CP-8 mode. That is, each of the first and second coil groups includes CP + 1 mode, CP + 2 mode, CP + 3 mode, CP + 4 mode, CP + 5 mode, CP + 6 mode, CP + 7 mode, CP + 8 mode. Any one of, CP-1 mode, CP-2 mode, CP-3 mode, CP-4 mode, CP-5 mode, CP-6 mode, CP-7 mode, CP-8 mode may be applied.

Referring to [Table 2], when CP + 3 mode is applied to an odd channel that is a first coil group, for example, a zero degree phase value is applied to a first channel having n value of 1, and a second value of n value of 2 is used. A +67.5 degree phase value is applied to three channels, a +135 degree phase value is applied to a fifth channel having an n value of 3, a +202.5 degree phase value is applied to a seventh channel having an n value of 4, and an n value A +270 degree phase value is applied to the ninth channel of 5, a +337.5 degree phase value is applied to the eleventh channel having an n value of 6, and a +405 degree phase value is applied to a thirteenth channel having an n value of 7. A phase value of +472.5 degrees is applied to the fifteenth channel having an n value of eight.

On the other hand, when the CP-7 mode is applied to the even channel, which is the second coil group, for example, a zero degree phase value is applied to the second channel having an n value of 1, and -180 degrees to a fourth channel having an n value of 2. A phase value is applied, a -360 degree phase value is applied to the sixth channel having an n value of 3, a -540 degree phase value is applied to an eighth channel having an n value of 4, and a tenth channel having an n value of 5 is applied. A -630 degree phase value is applied, a -787.5 degree phase value is applied to the twelfth channel having an n value of 6, a -945 degree phase value is applied to a fourteenth channel having an n value of 7, and an n value is 8 A phase value of -1102.5 degrees is applied to the sixteenth channel.

Referring to [Table 2], when CP + 2 mode is applied to an odd channel that is a first coil group, for example, a zero degree phase value is applied to a first channel having n value of 1, and a second value of n value of 2 is used. The +45 degree phase value is applied to three channels, the +90 degree phase value is applied to the fifth channel having n value 3, the +135 degree phase value is applied to the seventh channel having n value 4, and the n value is A +180 degree phase value is applied to the ninth channel of 5, a +225 degree phase value is applied to the eleventh channel having an n value of 6, and a +270 degree phase value is applied to a thirteenth channel having an n value of 7. A phase value of +315 degrees is applied to the fifteenth channel having an n value of eight.

On the other hand, when CP-1 mode is applied to an even channel, which is a second coil group, for example, a zero degree phase value is applied to a second channel having an n value of 1, and a -22.5 degree phase is applied to a fourth channel having an n value of 2. Value is applied, the -45 degree phase value is applied to the sixth channel with n value 3, the -67.5 degree phase value is applied to the eighth channel with n value 4, and the tenth channel with n value 5 is applied. A -90 degree phase value is applied, a -112.5 degree phase value is applied to the twelfth channel having an n value of 6, a -135 degree phase value is applied to a fourteenth channel having an n value of 7, and an n value is 8 A phase value of -157.5 degrees is applied to the sixteenth channel.

Although described above with reference to a preferred embodiment of the present invention, those of ordinary skill in the art various modifications and variations of the present invention without departing from the spirit and scope of the invention described in the claims below It will be appreciated that it can be changed.

Claims

In the multi-channel RF coil array for magnetic resonance imaging apparatus,

The multi-channel RF coil array includes L coil elements surrounding the object under test circularly,

The L coil elements are divided into a plurality of coil groups composed of a plurality of coil elements, and a plurality of current phase values increasing by an integer multiple of 360 ° / L are applied to the plurality of coil elements belonging to each coil group. The plurality of current phase values applied to each coil group are independently applied to the plurality of current phase values applied to another coil group.

Multichannel RF Coil Array for Magnetic Resonance Imaging.
The method of claim 1,

The multi-channel RF coil array includes 2 x N coil elements surrounding the object under test circularly,

The 2 × N coil elements,

A first coil group composed of N coil elements arranged in an odd number along the circumferential direction of the multichannel RF coil array;

A second coil group composed of N coil elements disposed in even-numbered positions along the circumferential direction,

The coil elements of each of the first coil group and the second coil group are applied with currents according to any one of CP modes of 2 × N branch current phase (CP) modes defined by the following CP mode equation. ,

CP (M, n) = {360 ° / (2 × N)} × M × (n-1)

In the above formula, N is a natural number equal to or greater than 4, M is a number specifying a mode and is an integer other than 0 between -N and N, and n is a natural number between 1 and N indicating the arrangement order of each coil element in each group. sign,

Multichannel RF Coil Array for Magnetic Resonance Imaging.