JP4078348B2 - Magnetic resonance imaging apparatus and high-frequency coil used in the magnetic resonance imaging apparatus - Google Patents

Description

  The present invention relates to a signal detection high-frequency coil that applies a high-frequency pulse to a subject in a static magnetic field to generate a magnetic resonance signal and simultaneously acquires the magnetic resonance signal, and a magnetic resonance imaging apparatus using the high-frequency coil. .

A magnetic resonance imaging (MRI) device resonates the energy of a high-frequency magnetic field rotating at a specific frequency when a group of nuclei having a specific magnetic moment is placed in a uniform static magnetic field. It is a device that visualizes chemical and physical microscopic information of a substance or observes a chemical shift spectrum by utilizing a phenomenon of absorption. Among recent technologies relating to this magnetic resonance imaging apparatus, there is a phased array technology in which a plurality of surface coils are arranged for a region of interest, and a magnetic resonance signal is received to acquire a high S / N image.
As an example, a plurality of surface coils (for example, loop coils) are arranged in a desired region to be imaged of a subject, and a magnetic resonance signal is detected through each of the plurality of surface coils. There is a resonance imaging apparatus (see, for example, Patent Document 1). The detected magnetic resonance signals are converted into a plurality of series of image data by imaging processing, and those corresponding to the same spatial position are determined based on a predetermined weight function (distribution of a high-frequency magnetic field generated by each surface coil, Multiply by a predetermined function) and add. By creating data of each pixel obtained in this way and synthesizing them, a high S / N image of the entire desired region of the subject is provided.

  In recent years, a parallel imaging method (hereinafter referred to as “PI method”), which is a high-speed imaging method using a multi-surface coil, has been proposed (see, for example, Non-Patent Document 1, Non-Patent Document 2, and Patent Document 2). ). Furthermore, there is also a phased array technique as a noticeable technique (for example, see Non-Patent Document 3). According to these methods, when a plurality of surface coils are arranged around the region of interest, the data amount in the encoding direction in the raw MRI data can be reduced by the reciprocal of the number of coils arranged in that direction. For example, when acquiring an axial image of a 256 × 256 matrix, assuming that the X direction is the lead direction and the Y direction is the encode direction, 256 data sampling is performed while applying a gradient magnetic field in the normal X direction. The gradient magnetic field pulse in the Y direction is repeated 256 times while changing the intensity stepwise in a predetermined step to obtain 256 × 256 raw data. An axial image can be obtained by Fourier transforming this. Here, when the PI method is applied by arranging two surface coils so as to sandwich the subject vertically, even if the number of times of data collection is reduced to 128 times while changing the gradient magnetic field pulse in the Y direction to a predetermined intensity, A 256 × 256 image can be reproduced satisfactorily.

Thus, the data collection time T is reduced to 1 / n, and the S / N ratio is reduced to 1 / n ^1/2 . Accordingly, by collecting data using a plurality of surface coils having a high S / N ratio, it is possible to cover the deterioration of the S / N ratio due to a reduction in data collection time. Furthermore, if the surface coils are arranged in the X direction or Z direction (static magnetic field direction), the number of encoding can be reduced according to the number of coils arranged even when encoding is performed in the X direction or Z direction, and the data collection time is reduced. be able to. That is, it is considered that high-speed imaging becomes possible.
However, in the conventional magnetic resonance imaging apparatus, in particular, when an abdominal region is imaged using the PI method, high-frequency coils are arranged in two directions of X and Y. There was never a coil in the direction. Accordingly, the number of encodings cannot be reduced in the Z direction, and it may be difficult to apply the PI method when a cross section in an arbitrary direction is selected (oblique imaging).
JP 4-42937 Magnetic Resonance in Medicine 29: 681-68 (1993) Magnetic Resonance in Medicine 30: 142-145 (1993) U.S. Pat. No. 4,857,846 Magnetic Resonance in Medicine, 42, 952 to 962 (1999)

The present invention has been made in view of the above circumstances, and in an imaging method using a plurality of surface coils, the PI method can be freely applied to a cross section in an arbitrary direction, whereby a high S / N ratio can be achieved. An object of the present invention is to provide a magnetic resonance imaging apparatus which can be realized and can obtain a magnetic resonance image at high speed, and a high-frequency coil used in the apparatus.

  In order to achieve the above object, the present invention takes the following measures.

A first aspect of the present invention is a high-frequency coil unit used in a magnetic resonance imaging apparatus for imaging a magnetic resonance signal generated from a subject placed in a static magnetic field, for receiving the magnetic resonance signal. And a plurality of coils for receiving the magnetic resonance signal, the first unit being arranged in two or more in each of the first direction and the second direction orthogonal to the first direction. Two or more units are arranged for each of the first direction and the second direction, and the first direction is along a third direction orthogonal to both the first direction and the second direction. A second unit disposed with respect to the unit, and the coil units of the first and second units are respectively in the first direction, the second direction, and the third direction. Who It can execute to output the magnetic resonance signal the parallel imaging in a high frequency coil unit according to claim.

The invention described in claim 1 is a high-frequency coil used in a magnetic resonance imaging apparatus for imaging a magnetic resonance signal generated from a subject placed in a static magnetic field, and is arranged so as to be orthogonal to each other. Two or more coil units each having a QD coil for detecting magnetic resonance signals substantially orthogonal by a plurality of 8-shaped coils are arranged in each of the first direction and the second direction orthogonal to the first direction. 1 unit and a coil unit having a QD coil for detecting a magnetic resonance signal substantially orthogonal by a plurality of 8-shaped coils arranged to be orthogonal to each other in each of the first direction and the second direction. And a second unit arranged with respect to the first unit along a third direction orthogonal to both the first direction and the second direction. The coil units of the first and second units are capable of performing parallel imaging in each of the first direction, the second direction, and the third direction. The high-frequency coil is characterized by outputting a resonance signal .
The invention according to claim 7 is a high-frequency coil used in a magnetic resonance imaging apparatus for imaging a magnetic resonance signal generated from a subject placed in a static magnetic field, and includes a loop coil and an 8-shaped coil. A first unit in which two or more coil units each having a QD coil for detecting a substantially perpendicular magnetic resonance signal are arranged in each of a first direction and a second direction orthogonal to the first direction; and a loop shape Two or more coil units each having a QD coil for detecting a magnetic resonance signal substantially orthogonal to each other by the coil and the 8-shaped coil are arranged in each of the first direction and the second direction, and the first direction and the A second unit disposed with respect to the first unit along a third direction orthogonal to both of the second directions, the first and second Coil unit units in the first direction, the second direction and the third high-frequency coil output the respective executable in the magnetic resonance signals parallel imaging in the direction of direction, characterized by the There is .
According to an eighth aspect of the present invention, in a magnetic resonance imaging apparatus for imaging a magnetic resonance signal generated from a subject placed in a static magnetic field, a plurality of eight-shaped coils arranged in an orthogonal manner are substantially used. A coil unit having a QD coil for detecting orthogonal magnetic resonance signals is orthogonal to the first unit arranged in two or more in each of the first direction and the second direction orthogonal to the first direction. Two or more coil units each having a QD coil for detecting a magnetic resonance signal substantially orthogonal to each other by a plurality of eight-shaped coils arranged on top of each other are arranged in each of the first direction and the second direction, a high-frequency coil having a second unit disposed to the first direction and the second direction of the third along said direction of the first unit that is orthogonal to both, and The magnetic resonance signals output from the coil units of the first and second units so that parallel imaging can be performed in each of the first direction, the second direction, and the third direction. A magnetic resonance imaging apparatus comprising: generating means for generating a magnetic resonance image on the basis thereof.
According to a ninth aspect of the present invention, in a magnetic resonance imaging apparatus for imaging a magnetic resonance signal generated from a subject placed in a static magnetic field , a substantially perpendicular magnetic resonance signal is detected by a loop-shaped coil and an 8-shaped coil. A coil unit having a QD coil to be operated is roughly constituted by a first unit in which two or more are arranged in each of a first direction and a second direction orthogonal to the first direction, a loop coil, and an 8-shaped coil. Two or more coil units having QD coils that detect orthogonal magnetic resonance signals are arranged in each of the first direction and the second direction, and are orthogonal to both the first direction and the second direction. the third and the second unit being positioned relative to the first unit along a direction of a high-frequency coil having a carp of the first and second units Generation means for generating a magnetic resonance image based on the magnetic resonance signal output from the unit so that parallel imaging can be executed in each of the first direction, the second direction, and the third direction. And a magnetic resonance imaging apparatus.

According to such a configuration, in the imaging method using a plurality of surface coils, a magnetic resonance image can be obtained at a high S / N ratio or at high speed by configuring the coil so that the PI method can be freely applied. Can be realized, and a high-frequency coil used in the apparatus.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, components having substantially the same function and configuration are denoted by the same reference numerals, and redundant description will be given only when necessary.

  FIG. 1 is a block diagram showing the configuration of the magnetic resonance imaging apparatus according to the present embodiment. In the figure, a magnetic resonance imaging apparatus 10 includes a static magnetic field magnet 11, a gradient coil 13, a shim coil 12, a high frequency coil 14, a gradient coil power supply 16, a shim coil power supply 17, a transmission unit 18, a reception unit 19, a data collection unit 20, and a sequence. A control unit 21, a computer system 22, a console 23, and a display 24 are provided.

  The static magnetic field magnet 11 is a magnet that generates a static magnetic field, and generates a uniform static magnetic field. For example, a permanent magnet or a superconducting magnet is used as the static magnetic field magnet 11.

  The gradient coil 13 is provided inside the static magnetic field magnet 11 and converts a pulse current supplied from the gradient coil power supply 16 into a gradient magnetic field. The signal generation site (position) is specified by the gradient magnetic field generated by the gradient coil 13.

  The shim coil 12 is provided inside the static magnetic field magnet 11 and is a coil for actively increasing the uniformity of the magnetic field. The shim coil 12 is driven by a shim coil power supply 17.

The shim coil 12 and the gradient coil 13 apply a uniform static magnetic field to a subject (not shown) and a gradient magnetic field having a linear gradient magnetic field distribution in three directions X, Y, and Z orthogonal to each other. In this embodiment, the Z-axis direction is the same as the direction of the static magnetic field.

  The high-frequency coil (RF coil) device is in close contact with, preferably in close contact with, a high-frequency coil for transmission 140 that applies a high-frequency pulse for generating a magnetic resonance signal to the imaging region of the subject. The receiving high-frequency coil 14 is installed so as to sandwich the subject and receives magnetic resonance from the subject. The high frequency coil 14 generally has a dedicated shape for each part.

  The high-frequency coil 14 has a plurality of surface coils arranged in the X, Y, and Z directions orthogonal to each other. This will be described in detail later.

  The transmitting unit 18 includes an oscillating unit, a phase selecting unit, a frequency converting unit, an amplitude modulating unit, and a high frequency power amplifying unit (each not shown), and applies a high frequency pulse corresponding to the Larmor frequency to the transmitting high frequency coil 140. Send. Due to the high frequency generated from the high frequency coil 14 by the transmission, the magnetization of a predetermined nucleus of the subject is in an excited state.

  The receiver 19 has an amplifier, an intermediate frequency converter, a phase detector, a filter, and an A / D converter (each not shown). The receiving unit 19 amplifies the magnetic resonance signal (high frequency signal) received from the high frequency coil 14 and releases when the nuclear magnetization relaxes from the excited state to the ground state, and intermediate frequency conversion processing using the transmission frequency. , Phase detection processing, filter processing, and A / D conversion processing are performed.

  The data collecting unit 20 collects the digital signal sampled by the receiving unit 19.

  The sequence control unit 21 controls the gradient coil power supply 16, the shim coil power supply 17, the transmission unit 18, the reception unit 19, and the data collection unit 20.

  The computer system 22 controls the sequence control unit 21 based on a command input from the console 23. In addition, the computer system 22 performs post-processing, that is, reconstruction such as Fourier transform, on the magnetic resonance signal input from the data collection unit 20 to obtain spectrum data or image data of the desired nuclear spin in the subject. .

  The console 23 has an input device (mouse, trackball, mode changeover switch, keyboard, etc.) for incorporating various instructions, commands, and information from the operator.

  The display 24 is output means for displaying spectrum data or image data input from the computer system 22.

(High frequency coil)
Next, the configuration of the high frequency coil will be described in more detail.

  FIG. 2 is a diagram showing the high-frequency coil 14 including the upper unit 140 and the lower unit 141 used for diagnosing the abdomen, for example. As shown in FIG. 2, the upper unit 140 and the lower unit 141 each have a configuration in which two rows of coil units 142 in the X direction and three rows in the Z direction are arranged. The upper unit 140 and the lower unit 141 are arranged to face each other along the Y direction. Therefore, the high-frequency coil 14 includes two rows of coil units 142 as surface coils in the X direction, three rows of coil units 142 as surface coils in the Z direction, an upper unit 140 and a lower portion as surface coils in the Y direction. The unit 141 has a configuration in which a total of 12 surface coils are arranged. Therefore, when the PI method is executed by this high-frequency coil, the number of times of data collection by encoding of gradient magnetic field pulses can be reduced to 1/2 for the X direction, 1/3 for the Y direction, and 1/3 for the Z direction. it can.

FIG. 3 shows a block diagram of the high-frequency coil 14. The upper unit 140 and the lower unit 141 are coupled by the first cable 40 and the first connector 41. The magnetic resonance signals detected by the surface coil of the upper unit 140 are received once by the lower unit 141 through the cable 40 with the connector 41, and collectively, the signal processing system (to the main body of the magnetic resonance imaging apparatus 10 through the cable 42 and the connector 43). Built-in).
As described above, a plurality of coil units 142 are arranged in the X direction and the Z direction in the upper unit 140 and the lower unit 141, respectively. FIG. 3 shows a coil unit 142 composed of a circular coil and an 8-shaped coil. A specific example of the coil unit 142 will be described in detail later. In addition, the lower unit 141 includes a preamplifier 44 connected to each coil, and a hybrid circuit 45 that synthesizes a signal of a coil unit 142 described later by changing the phase by 90 °.

In actual imaging, the subject is placed on the lower unit 141, and the upper unit 140 is placed on the subject so as to face the lower unit 141 (see FIGS. 4 and 5). The high frequency coil 14 has a configuration in which the upper unit 140 and the lower unit 141 are connected by a connector so that the number of components included in the upper unit 140 is reduced as much as possible. Therefore, the upper unit 140 is sufficiently lightened, and the load on the subject can be reduced.
The high-frequency coil 14 including the upper unit 140 and the lower unit 141 shown in FIG. 2 or 3 is normally used while being fixed to a subject. This mode of use will be described with reference to FIGS.

4 and 5 are diagrams showing an example of the high-frequency coil 14 including the upper unit 140 and the lower unit 141, which is used while being fixed to the subject. The high-frequency coil 14 including the upper unit 140 and the lower unit 141 shown in each figure is particularly suitable when imaging the thoracoabdominal region. The high-frequency coil 14 is used, for example, in the following manner when photographing a magnetic resonance image. That is, in FIG. 4, the subject is laid on the lower unit 141, and the upper unit 140 is placed on the subject. The lower unit 141 is placed on a bed (not shown), and the upper unit 140 is fixed to the lower unit 141 by a band 47.
In addition, it is preferable that the upper unit 140 and the lower unit 141 are arrange | positioned fixedly, especially arrange | positioning facing along a Y direction. For this reason, the high frequency coil 14 has a mark 46 for reference in the arrangement of the upper unit 140 and the lower unit 141. The operator can easily align the high-frequency coil 14 by arranging the upper unit 140 so that the mark 46 between the upper unit 140 and the lower unit 141 faces each other. Further, as shown in FIG. 5, instead of the mark 46, the groove 10 may be arranged as the outer shape of the upper unit 140 so that the position can be adjusted when the band 47 is fixed.

  Further, the high frequency coil 14 may have a form having a predetermined shape for arranging the upper unit 140 on the subject.

  FIG. 6 is a view for explaining the form of the high-frequency coil 14 having the form 50. As shown in FIG. 6, when the upper unit 140 is put on the subject, the foam 50 is disposed between the upper unit 140 and the subject. The foam 50 serves to stabilize the shape of the upper unit 140.

In general, in the PI method, pre-scanning for obtaining a high-frequency magnetic field distribution of each surface coil is performed before this data collection. It is preferable that the position of the high-frequency coil 14 in this pre-scan and the position of the high-frequency coil 14 in this data collection are the same. According to the high-frequency coil 14, the presence of the form 50 can stabilize the shape and prevent the coil position from changing, and can perform good data collection.
(Surface coil)
The high-frequency coil 14 has a coil unit 142 as a surface coil in the X direction and the Z direction, and an upper unit 140 and a lower unit 141 as surface coils in the Y direction. Here, a specific aspect of a coil suitable for incorporation as the coil unit 142 will be described in detail.

  FIG. 7 shows a first surface QD coil 51 as a coil unit 142 composed of a loop-shaped coil 53 and an 8-shaped coil 55. As shown in FIG. 7, in the first surface QD coil 51, the loop-shaped coil 53 is preferably disposed at the center of the 8-shaped coil 55. This is because the electrical coupling between the loop-shaped coil 53 and the 8-shaped coil 55 can be suppressed by taking such an arrangement. The first surface QD coil 51 has a static magnetic field direction that is substantially lateral (Z direction) with respect to the 8-shaped type of the 8-shaped coil 55 (that is, the body of the subject lying down). (When the axial direction is the static magnetic field direction).

  FIG. 8 shows a second surface QD coil 57 as a coil unit 142, which is composed of an 8-shaped coil 55a and an 8-shaped coil 55b. As shown in FIG. 8, in the second surface QD coil 57, the 8-shaped coil 55a and the 8-shaped coil 55b are preferably arranged so as to be orthogonal to each other. This is because, like the first surface QD coil 51, electrical coupling between the 8-shaped coil 55a and the 8-shaped coil 55b can be suppressed. The second surface QD coil 57 is suitable when the static magnetic field direction is perpendicular to the surface formed by the 8-shaped coil (that is, when the static magnetic field direction is in the Y direction). .

In the high frequency coil 14, for example, first or second surface QD coils as the coil unit 142 are arranged in the X direction or the Z direction. However, in the case where a plurality of surface coils adjusted to the same resonance frequency are arranged in this manner and data is collected simultaneously, it is important to suppress electrical coupling between the coils. There are the following two methods for suppressing this electrical coupling. One is a method of suppressing coupling by adjusting a spatial arrangement. The other is a method in which a preamplifier having a low input impedance is used as a preamplifier that is coupled to a coil and amplifies a signal, as disclosed in Japanese Patent Publication No. 4-42937.
FIG. 9 is a diagram showing an example in which a method of suppressing the coupling by adjusting the spatial arrangement is applied to the high-frequency coil 14. Specifically, the first coil shown in FIG. This is an example in which when the surface QD coils 51 are arranged in two rows in two dimensions (XZ plane), the spatial arrangement is adjusted to suppress coupling.
As shown in FIG. 9, when the 8-shaped coil 55 </ b> A, the 8-shaped coil 55 </ b> B, the 8-shaped coil 55 </ b> C, and the 8-shaped coil 55 </ b> D are adjacent to each other in the X or Z direction, The electrical coupling is suppressed by arranging them in an overlapping manner. Further, the loop-shaped coil 53A and the loop-shaped coil 53C, and the loop-shaped coil 53B and the loop-shaped coil 53D are also arranged to overlap each other in order to suppress electrical coupling.

  In FIG. 9, the eight-shaped coils positioned in the diagonal relationship, the loop-shaped coils arranged in the X direction, the loop-shaped coils positioned in the diagonal relationship, and the adjacent relationship between the eight-shaped coils. In order to suppress the coupling between the loop coils, the spatial arrangement is not sufficient. In principle, even if it is possible to decouple by overlapping, there may be a manufacturing error and the coupling may remain. In such a case, sufficient suppression of coupling can be achieved by using the above-described method using an amplifier with low input impedance.

  Although the coupling is reduced as much as possible by the above method, it is possible to prevent the central sensitivity from being lowered by the method described below even when there is a residual coupling. 10 and 11 are diagrams for explaining the method. In the present method, for example, the arrangement or wiring of the upper unit 140 and the lower unit 141 is devised so as not to reduce the sensitivity of the region of interest.

In general, when coils are coupled to each other, there are two types: a mode in which a high-frequency current flows in a direction that cancels out the high-frequency magnetic field that is normally generated, and a mode in which a high-frequency current flows in a direction that generates and strengthens the high-frequency magnetic field. In the former case, since the high-frequency magnetic fields generated by each other are canceled, the sensitivity at the center of the sandwiched subject decreases. On the other hand, in the latter case, cancellation of the high-frequency magnetic field does not occur, and the sensitivity does not decrease.
Therefore, even if it is a case where it couples, the sensitivity fall of a region of interest can be prevented by devising arrangement | positioning of the wiring of a signal cable or a coil so that the latter mode can be selected.

  FIG. 10 shows a wiring method applied to the upper part of the loop coil 53 included in the upper unit 140 and the lower part of the loop coil 53 included in the lower unit 141 in order to prevent the sensitivity of the region of interest from decreasing. In FIG. 10, the side connected to the ground side of the signal cable is the C side (cold side), and the other side is the H side (hot side). Then, since the H side and the C side coincide between the loop coil 53 and the loop coil 53, the phases of the signals to be detected are the same. Therefore, the directions of the high-frequency currents are the same, the directions of the generated high-frequency magnetic field are the same, and the sensitivity reduction due to coupling can be prevented.

FIG. 11 shows wiring applied to the upper part of the 8-shaped coil 55 of the upper unit 140 and the lower part of the 8-shaped coil 55 of the lower unit 141. As shown in FIG. 11, in order to make the direction of the high frequency magnetic field generated between the 8-shaped coils the same, the H side and the C side are reversed between the upper coil and the lower coil. do it.
Next, effects achieved by the above-described high-frequency coil and magnetic resonance imaging apparatus will be described.

  This magnetic resonance imaging apparatus has a plurality of surface coils arranged in X, Y, and Z directions orthogonal to each other. Therefore, the imaging time T can be significantly shortened in the imaging method using the PI method. Further, the high sensitivity characteristic of the surface coil can cover the S / N that decreases as the imaging time T is shortened, and it is possible to acquire a highly accurate magnetic resonance image. The improvement of the S / N ratio will be specifically described below with a focus on the configuration of the high-frequency coil in the Z direction.

  The magnetic resonance imaging apparatus 10 includes a high frequency coil 14 in which a plurality of coil units 142 are arranged in the Z direction. On the other hand, the conventional high frequency coil only has an integral coil in the Z direction. The improvement in the S / N ratio due to the difference in the configuration in the Z direction can be confirmed as follows. That is, for example, as shown in FIG. 12, the phantom 61 is imaged by an integrated long-axis volume coil 60, and as shown in FIG. 13, two short-axis volume coils 63, 64 arranged in the Z direction. The sensitivity (S / N ratio) on the central body axis is compared by computer simulation.

  FIG. 14 is a diagram showing the results of the computer simulation. As shown in FIG. 14, it can be seen that the short-axis volume coils 63 and 64 have higher sensitivity than the long-axis volume coil 60.

13 corresponds to the present magnetic resonance imaging apparatus in which a plurality of surface coils are arranged in the Z direction, while the long axis volume coil model in FIG. 12 has a plurality of models in the Z direction. This corresponds to a conventional magnetic resonance imaging apparatus in which the surface coils are not arranged (that is, an integrated coil that is long in the Z direction is used). Therefore, a signal can be acquired with a higher S / N ratio than before.

  The high-frequency coil 14 is provided with a band for fixing to the subject and a reference for suitable arrangement. Furthermore, the QD coil constituting each surface coil exhibits the maximum high S / N ratio characteristics as a surface coil. Furthermore, by devising the wiring method, the sensitivity of the central region is not lowered even if there is residual coupling. A high S / N ratio can also be realized by each of these configurations.

  Although the present invention has been described based on the embodiments, those skilled in the art can come up with various changes and modifications within the scope of the idea of the present invention. It is understood that it belongs to the scope of the present invention. For example, as shown below, various modifications can be made without changing the gist thereof.

The high-frequency coil 14 can have a different shape depending on the imaging region. FIG. 15 shows an example of the upper unit 140 particularly suitable for chest imaging. As shown in FIG. 15, in the upper unit 140, loop-shaped coils 53G, H, I, and J as surface coils are arranged in the X direction and the Z direction. Moreover, in order to reduce the coupling between coils, a part of adjacent loop-shaped coil is arrange | positioned so that it may overlap.
Further, the shape of the surface coil is not limited to a circular shape, and may be a form having another loop-shaped coil 70 as shown in FIG. 16, for example.

  Furthermore, the embodiments may be combined as appropriate as possible, and in that case, combined effects can be obtained. The above-described embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent requirements. For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, the problem described in the column of the problem to be solved by the invention can be solved, and the effect described in the column of the effect of the invention If at least one of the following is obtained, a configuration in which this configuration requirement is deleted can be extracted as an invention.

As described above, according to the present invention, in the imaging method using a plurality of surface coils, the PI method can be freely applied to a cross section in an arbitrary direction, thereby obtaining a magnetic resonance image at a high S / N ratio or at high speed. The magnetic resonance imaging apparatus which can be used, and the high frequency coil used with the said apparatus are realizable.

FIG. 1 is a block diagram showing the configuration of the magnetic resonance imaging apparatus according to the present embodiment. FIG. 2 is a diagram showing the high-frequency coil 14 including the upper unit 140 and the lower unit 141 used for diagnosing the abdomen, for example. FIG. 3 is a block diagram of the high-frequency coil 14. FIG. 4 is a diagram illustrating an example of the high-frequency coil 14 including the upper unit 140 and the lower unit 141 that is used while being fixed to a subject. FIG. 5 is a diagram showing another example of the high-frequency coil 14 including the upper unit 140 and the lower unit 141 that is used while being fixed to the subject. FIG. 6 is a view for explaining the form of the high-frequency coil 14 having the form 50. FIG. 7 shows a surface QD coil composed of a loop-shaped coil 53 and an 8-shaped coil 55. FIG. 8 shows a second surface QD coil 57 as a coil unit 142, which is composed of an 8-shaped coil 55a and an 8-shaped coil 55b. FIG. 9 is a diagram showing an example in the case of applying a method for suppressing coupling in the high-frequency coil 14. FIG. 10 shows a wiring method applied to the upper part of the loop coil 53 included in the upper unit 140 and the lower part of the loop coil 53 included in the lower unit 141 in order to prevent the sensitivity of the region of interest from decreasing. FIG. 11 shows a wiring method applied to the upper side of the 8-shaped coil 55 included in the upper unit 140 and the lower side of the 8-shaped coil 55 included in the lower unit 141 in order to prevent the sensitivity of the region of interest from decreasing. FIG. 12 is a diagram for explaining the effect of the magnetic resonance imaging apparatus. FIG. 13 is a diagram for explaining the effect of the magnetic resonance imaging apparatus. FIG. 14 is a diagram showing the results of the computer simulation. FIG. 15 shows an example of the upper unit 140 suitable for chest imaging. FIG. 16 shows another example of the upper unit 140 suitable for chest imaging.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Magnetic resonance imaging device, 11 ... Static magnetic field magnet, 12 ... Shim coil, 13 ... Gradient coil, 14 ... High frequency coil, 16 ... Gradient coil power supply, 17 ... Shim coil power supply, 18 ... Transmission part, 19 ... Reception part, 20 ... Data collection unit, 21 ... sequence control unit, 22 ... computer system, 23 ... console, 24 ... display, 40, 42 ... cable, 41, 43 ... connector, 44 ... preamplifier, 45 ... hybrid circuit, 46 ... mark, 47 ... Band, 50 ... foam, 53 ... loop coil, 55 ... 8-shaped coil, 140 ... upper unit, 141 ... lower unit, 142 ... coil unit

Claims (9)

A high-frequency coil used in a magnetic resonance imaging apparatus for imaging a magnetic resonance signal generated from a subject placed in a static magnetic field,
A coil unit having a QD coil that detects a magnetic resonance signal that is substantially orthogonal by a plurality of eight-shaped coils that are arranged so as to be orthogonal to each other has a first direction, a second direction orthogonal to the first direction. A first unit arranged in two or more for each;
Two or more coil units each having a QD coil for detecting a substantially orthogonal magnetic resonance signal by a plurality of eight-shaped coils arranged so as to be orthogonal to each other are arranged in each of the first direction and the second direction. And a second unit disposed with respect to the first unit along a third direction orthogonal to both the first direction and the second direction,
The coil units of the first and second units output the magnetic resonance signal so that parallel imaging can be performed in each of the first direction, the second direction, and the third direction. ,
High frequency coil characterized by 2. The high-frequency coil according to claim 1, further comprising first transmission means for independently transmitting each magnetic resonance signal received by the plurality of coil units of the first unit to the second unit. . The magnetic resonance signals received by the plurality of coil units of the second unit and the magnetic resonance signals transmitted by the first transmission unit are independently used by the signal processing unit of the magnetic resonance imaging apparatus. The high frequency coil according to claim 1 or 2, further comprising a second transmitting means for transmitting. 4. The plurality of 8-shaped coils are arranged so as to partially overlap with adjacent 8-shaped coils in at least one of the three directions. 5. The high frequency coil described. Among the plurality of coil units, coils facing each other and adjacent coils are connected so as to acquire substantially in-phase magnetic resonance signals. The high frequency coil as described in any one of Claims. The first direction is an X direction and the second direction is a Z direction, or the first direction is a Z direction and the second direction is an X direction;
The high frequency coil according to any one of claims 1 to 5, wherein: A high-frequency coil used in a magnetic resonance imaging apparatus for imaging a magnetic resonance signal generated from a subject placed in a static magnetic field,
Two or more coil units each having a QD coil for detecting a magnetic resonance signal substantially orthogonal to each other by a loop coil and an 8-shaped coil are arranged in each of a first direction and a second direction orthogonal to the first direction. The first unit,
Two or more coil units each having a QD coil for detecting a magnetic resonance signal substantially orthogonal by a loop-shaped coil and an 8-shaped coil are arranged in each of the first direction and the second direction, and the first direction And a second unit disposed with respect to the first unit along a third direction orthogonal to both of the second directions,
The coil units of the first and second units output the magnetic resonance signal so that parallel imaging can be performed in each of the first direction, the second direction, and the third direction. ,
High frequency coil characterized by In a magnetic resonance imaging apparatus for imaging a magnetic resonance signal generated from a subject placed in a static magnetic field,
A coil unit having a QD coil that detects a magnetic resonance signal that is substantially orthogonal by a plurality of eight-shaped coils that are arranged so as to be orthogonal to each other has a first direction, a second direction orthogonal to the first direction. A coil unit having a QD coil that detects a magnetic resonance signal substantially orthogonal by a first unit that is arranged in two or more and a plurality of eight-shaped coils that are arranged so as to be orthogonal to each other. Two or more are arranged for each of the direction and the second direction, and are arranged with respect to the first unit along a third direction orthogonal to both the first direction and the second direction. A high frequency coil having a second unit;
The magnetic resonance signals output from the coil units of the first and second units so that parallel imaging can be performed in each of the first direction, the second direction, and the third direction. Generating means for generating a magnetic resonance image on the basis thereof;
A magnetic resonance imaging apparatus comprising: In a magnetic resonance imaging apparatus for imaging a magnetic resonance signal generated from a subject placed in a static magnetic field,
Two or more coil units each having a QD coil for detecting a magnetic resonance signal substantially orthogonal to each other by a loop coil and an 8-shaped coil are arranged in each of a first direction and a second direction orthogonal to the first direction. Two or more coil units having a first unit and a QD coil for detecting a magnetic resonance signal substantially orthogonal to each other by a loop coil and an 8-shaped coil are arranged in each of the first direction and the second direction. A high frequency coil having a second unit disposed with respect to the first unit along a third direction orthogonal to both the first direction and the second direction;
The magnetic resonance signals output from the coil units of the first and second units so that parallel imaging can be performed in each of the first direction, the second direction, and the third direction. Generating means for generating a magnetic resonance image on the basis thereof;
A magnetic resonance imaging apparatus comprising:

Images