JP2004097607A - Rf coil and magnetic resonance imaging device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an RF (radio frequency) coil having stable characteristics which can prevent circuit elements on the coil from being damaged by reducing an electric potential difference between adjacent coils in the RF coil of multiple channels being constituted by using single loop coil elements, and a magnetic resonance imaging device using the RF coil. <P>SOLUTION: This RF coil is constituted of four single loop coil elements 101 to 104 which form an approximately cylindrical shape. In the RF coil, two adjacent coil elements form a pair, and the two coil elements of each pair are connected by a common ground electric potential at the adjacent part. In a vicinity of the common ground electric potential, a signal outputting unit for an RF exciting signal is provided, and the RF exciting signal received by the coil elements is outputted through the signal outputting unit. Therefore, a voltage difference between adjacent coil elements is reduced, and circuit elements can be prevented from being damaged. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an RF (Radio Frequency) coil and a magnetic resonance imaging apparatus that performs imaging using the RF coil, in particular, a phased array RF coil using a single-loop coil element formed in a substantially cylindrical shape, The present invention relates to a magnetic resonance imaging apparatus using an RF coil.
[0002]
[Prior art]
In a magnetic resonance imaging apparatus, RF excitation of spins and reception of a magnetic resonance signal in which excited spins are generated in a living tissue of a subject to be imaged are performed, and based on the received signals, a biological tissue of the subject is detected. Visualize the interior.
[0003]
Some phased array coils for receiving magnetic resonance signals include, for example, four single-loop coil elements having a substantially cylindrical shape. These single loop coil elements are the same size, are formed in a loop along a cylindrical surface, and are assembled to form an overall cylindrical shape.
[0004]
The four single-loop coil elements are formed in pairs each of two, and are arranged to face each other with the central axis of the cylinder interposed therebetween. In addition, adjacent portions overlap each other so that mutual inductance between adjacent coils is zero, thereby suppressing signal interference between the coils.
The RF coil configured as described above is called a phased array coil when each channel (coil) independently receives a magnetic resonance signal.
[0005]
When performing imaging, a living tissue of the subject, for example, a site to be imaged, such as a human head, abdomen or a knee, is housed in a cylindrical internal space composed of four-channel single loop coil elements, and according to a predetermined protocol. By supplying an RF signal to a transmitting RF coil (or a transmitting / receiving RF coil), spins are excited in a living tissue of a subject housed in a cylindrical internal space, and a magnetic resonance signal generated by the spin is excited. For example, it is collected in a two-dimensional space or a three-dimensional space by a receiving RF coil as a spin echo (spinecho) or a gradient echo (gradient echo). The living tissue in the subject can be stereoscopically imaged by predetermined signal processing according to the collected echo signals.
[0006]
In the above-described conventional RF coil including a multi-channel phased array coil, a potential is determined in a power supply unit (signal output unit) of a coil element of each channel by a relationship with a system ground potential. In a conventional phased array coil, the coupling between the grounds is separated by using a balun.
[0007]
For example, in a four-channel phased array coil, an RF excitation signal is output to the outside via a balun to each of four cylindrically arranged coils. For example, two adjacent coil elements are each connected to a preamplifier (not shown) via a balun. Therefore, the RF excitation signal received by each coil element is amplified by the preamplifier and input to the data collection unit.
[0008]
[Patent Document 1]
JP-A-11-318851 [Patent Document 2]
Japanese Patent Application Laid-Open No. 2000-185021
[Problems to be solved by the invention]
In the above-described conventional RF coil and the magnetic resonance imaging apparatus using the same, a large voltage induced in the ground shield of the cable between the coil element and the system is applied to the balun provided in each coil element. If the induced voltage exceeds the withstand voltage of a circuit element such as a capacitor constituting the balun, the balun may be damaged. This may cause a problem such as instability of the electrical characteristics of the coil.
[0010]
The present invention has been made in view of the above circumstances, and an object of the present invention is to reduce the potential difference between adjacent coils in a multi-channel RF coil configured using a single loop coil, thereby reducing the potential difference between the coils. An object of the present invention is to provide an RF coil having stable operation characteristics while preventing breakage of a circuit element on a loop, and a magnetic resonance imaging apparatus using the RF coil.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, the RF coil of the present invention comprises four substantially single-cylindrical single-loop coil elements and two pairs of adjacent single-loop coil elements. The single loop coil element has a ground connection portion commonly connected to a ground potential at a location adjacent to each other, and a signal output portion for an RF excitation signal provided near the ground connection portion.
[0012]
Further, the magnetic resonance imaging apparatus of the present invention is a magnetic resonance imaging apparatus that generates an image of a subject based on a magnetic resonance signal received by applying a high-frequency magnetic field to a subject to be imaged under a static magnetic field and a gradient magnetic field. An imaging apparatus, comprising: an RF coil configured to receive a magnetic resonance signal excited by the subject by the high-frequency magnetic field, wherein the RF coil includes four substantially single-cylindrical single-loop coil elements; A single grounded coil element is formed in pairs, and two single looped coil elements in each pair are connected to a ground potential commonly at a place adjacent to each other, and a ground connection part is provided near the ground connection part. And a signal output unit for an RF excitation signal provided.
[0013]
In the present invention, preferably, the single-loop coil elements are arranged so as to overlap with each other so that mutual inductance between two adjacent coil elements is substantially zero.
[0014]
In the present invention, preferably, the single loop coil element is formed such that two adjacent coil elements overlap each other, and the area of the overlapping portion is equal to the area of the overlapping portion between the other adjacent coil elements. Have been.
[0015]
In the present invention, preferably, the single loop coil element is formed such that two adjacent coil elements overlap each other, and the area of the overlapping portion is about 10% of the area of the entire coil element. ing.
[0016]
Further, in the present invention, preferably, in the single loop coil element, the interval between two adjacent coil elements is formed to be equal to the interval between the other two adjacent coil elements.
[0017]
According to the present invention, in a receiving RF coil constituted by four single-loop coil elements having a substantially cylindrical shape, adjacent single-loop coil elements are paired two by two, and two of each pair are formed. The coil element is connected to a common ground potential at its adjacent part. An RF excitation signal output unit is provided near the common ground potential, and the RF excitation signal received by the RF coil is output to the data collection unit via the signal output unit.
In the receiving RF coil configured as described above, the voltage difference between adjacent coil elements is reduced, thereby preventing damage to circuit elements due to the voltage difference and improving the stability of electrical characteristics of the RF coil. Is done.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a magnetic resonance imaging system according to an embodiment of the present invention will be described with reference to the drawings.
[0019]
FIG. 1 is a configuration diagram showing an embodiment of a magnetic resonance imaging (MRI: Magnetic Resonance Imaging) system employing a magnetic resonance imaging apparatus according to the present invention.
[0020]
As shown in FIG. 1, the MRI system 10 according to the present embodiment includes an MRI apparatus 20 disposed in a scan room (not shown) that forms a closed space for preventing leakage of electromagnetic radiation emitted from a magnet and entry of disturbance electromagnetic waves. Further, for example, an operator console 30 provided in the operation room provided adjacent to the scan room has an operator console 30 as a main component.
[0021]
Hereinafter, the MRI apparatus 20 and the operator console 30 will be described step by step.
[0022]
As shown in FIG. 1, the MRI apparatus 20 has a magnet system 21, an RF drive unit 22, a gradient drive unit 23, a data collection unit 24, a control unit 25, and a cradle 26.
[0023]
As shown in FIG. 1, the magnet system 21 has a substantially cylindrical internal space (bore) 211 in which a cradle 26 on which the subject 50 is placed via a cushion is transported (not shown). Department.
[0024]
In the magnet system 21, as shown in FIG. 1, a main magnetic field magnet unit 212, a gradient coil unit 213, and an RF coil unit 214 are arranged around a magnet center (center position for scanning) in the bore 211. I have.
[0025]
The main magnetic field magnet section 212 and the gradient coil section 213 are composed of a pair of coils facing each other across a space in the bore 211 where the subject 40 is located at the time of examination.
[0026]
The main magnetic field magnet section 212 forms a static magnetic field in the bore 211. The direction of the static magnetic field is, for example, substantially parallel to the body axis direction of the subject 40. That is, a parallel magnetic field is formed. The pair of main magnetic field magnets constituting the main magnetic field magnet unit 212 is configured using, for example, a superconducting electromagnet, a permanent magnet, a normal electromagnet, or the like.
[0027]
The gradient coil unit 213 generates a gradient magnetic field for giving a gradient to the intensity of the static magnetic field formed by the main magnetic field magnet unit 212 so that the magnetic resonance signal received by the RF coil unit 214 has three-dimensional position information.
The gradient magnetic field generated by the gradient coil unit 213 is of three types: a slice gradient magnetic field, a read out gradient magnetic field, and a phase encode gradient magnetic field, and corresponds to these three gradient magnetic fields. The gradient coil unit 213 has three gradient coils.
[0028]
The RF coil unit 214 forms a high-frequency magnetic field for exciting spins in the body of the subject 40 in the static magnetic field space formed by the main magnetic field magnet unit 212. Here, forming a high-frequency magnetic field is called transmission of an RF excitation signal. The RF coil unit 214 receives, as a magnetic resonance signal, an electromagnetic wave in which a spin excited in the body of the subject 40 occurs.
The RF coil unit 214 has a transmitting coil and a receiving coil (not shown). The same coil is used for the transmitting coil and the receiving coil, or a dedicated coil is used for each.
[0029]
The RF coil unit 214 receives the driving signal DR1 corresponding to the protocol from the RF driving unit 22 and forms a high-frequency magnetic field.
In the magnetic resonance imaging processing, the number of pulse sequences (scan sequences) used for each 1TR (repeated time, a repetition cycle in magnetic resonance imaging) differs depending on a protocol set corresponding to each test site.
For example, the view data of 64 views to 512 views is obtained by repeating the procedure differently, for example, 64 times to 512 times for each protocol corresponding to the test site such as the head, the chest, and the abdomen.
[0030]
The RF drive unit 22 supplies a drive signal DR1 corresponding to a protocol based on an instruction from the control unit 25 to the RF coil unit 214 to generate an RF excitation signal, and excites spins in the body of the subject 40.
[0031]
The gradient driving unit 23 supplies a driving signal DR2 corresponding to a protocol based on an instruction from the control unit 25 to the gradient coil unit 213 to generate a gradient magnetic field.
The gradient drive unit 23 has three drive circuits (not shown) corresponding to the three gradient coils of the gradient coil unit 213.
[0032]
The data collection unit 24 captures the RF excitation signal received by the reception coil or the transmission / reception coil of the RF coil unit 214, and converts it into raw data (raw).
data) and output to the data processing unit 31 of the operator console 30.
[0033]
The control unit 25 performs a predetermined pulse sequence within a predetermined repetition time TR in accordance with a protocol to be executed corresponding to a test site of the subject 40 sent from the data processing unit 31 of the operator console 30. Is applied to the RF coil unit 214 so as to apply the drive signal DR1 that is repeated a predetermined number of times to the RF coil unit 214.
[0034]
Similarly, the control unit 25 controls the gradient driving unit 23 to apply a pulse signal of a predetermined pattern to the gradient coil 213 within 1TR according to the protocol to be executed.
Further, the control unit 25 controls the data collection unit 24 so as to capture the received signal received by the RF coil unit 214, collect the data as raw data, and output the raw data to the data processing unit 31 of the operator console 30.
[0035]
As shown in FIG. 1, the operator console 30 includes a data processing unit 31, an image database 32, an image processing database 33, an operation unit 34, and a display unit 35.
[0036]
The control unit 25 is connected to the data processing unit 31 and is located above the control unit 25 and controls it.
Further, an image database 32, an image processing database 33, an operation unit 34, and a display unit 35 are connected to the data processing unit 31.
[0037]
The data processing unit 31 stores the raw data fetched from the data collection unit 24 in a memory (not shown). A data space is formed in the memory. The data space formed in the memory constitutes a two-dimensional Fourier space.
The data processing unit 31 performs a two-dimensional inverse Fourier transform of the data in the two-dimensional Fourier space, that is, a conversion from the Fourier frequency space to the real space, and generates (reconstructs) an image of the subject 40.
Note that the two-dimensional Fourier space is also called a k-space.
[0038]
The data processing unit 31 reads from the image processing database 33 an image processing protocol that describes in which order a plurality of image processing applications, such as Fourier transform, image filter, and distortion correction, are to be performed, and processes the image according to the contents. I do. Then, the data processing unit 31 stores the reconstructed image data in the image database 32.
[0039]
The image database 32 is composed of, for example, a recordable / reproducible disk device, and records the raw data collected by the data collection unit 24 and the reconstructed reconstructed image data as described above. When processing is performed by the data processing unit 31 in accordance with the designated image processing application, the recorded raw data is read. In the normal imaging process, when the image is reconstructed, the reconstructed image is recorded in the image database 32, and the raw data is discarded. According to the instruction, the raw data can be stored in the image database 32.
[0040]
The image processing database 33 is composed of, for example, a disk device or the like capable of recording and reproducing. As described above, the image processing application program and the image processing protocol data are recorded, and are accessed by the data processing unit 31 as appropriate.
[0041]
The operation unit 34 includes a keyboard, a mouse, and the like provided with a pointing device, and outputs an operation signal corresponding to an operation of the operator to the data processing unit 31. Further, for example, the above-described protocol to be executed is input from the operation unit 34. The data processing unit 31 supplies information (protocol number and the like) relating to the protocol input from the operation unit 34 to the control unit 25.
[0042]
The display unit 35 is configured by a graphic display or the like, and displays predetermined information corresponding to the operation state of the MRI apparatus 20 according to an operation signal from the operation unit 34, and displays a reconstructed image by the data processing unit 31. I do.
[0043]
Next, a receiving RF coil used in the magnetic resonance imaging apparatus of the present embodiment will be specifically described with reference to the drawings.
[0044]
FIG. 2 shows a configuration example of an RF coil 100 used in the magnetic resonance imaging apparatus of the present embodiment.
As shown, the RF coil 100 is constituted by four coil elements 101, 102, 103 and 104. The four coil elements 101 to 104 are single loop coils, and the four single loop coil elements are assembled in a cylindrical shape.
[0045]
In the receiving RF coil 100 of this example, the MR signals induced in the living tissue of the subject are independently collected by the four coil elements 101 to 104. That is, the receiving RF coil 100 of the present embodiment is configured by a phased array coil of four channels.
[0046]
Further, as shown in FIG. 2, in the receiving RF coil 100, adjacent coil arrays are arranged so as to partially overlap (overlap) each other. The area of the overlap portion is arranged so as to be approximately 10% of the entire area of the coil element.
Further, two adjacent coil elements form a pair, and the ground potential of the two coil elements of each pair is shared. That is, as illustrated, the coil elements 101 and 102 are held at a common ground potential, and the coil elements 103 and 104 are held at a common ground potential. The signal output unit that outputs the RF excitation signal to each coil element is set at a location where the ground potential is shared on the coil elements forming the loop.
[0047]
FIG. 3 is a cross-sectional view of the receiving RF coil 100 shown in FIG. 2 as viewed from the long axis direction of the cylinder. As illustrated, the four single-loop coil elements 101 to 104 constituting the RF coil 100 form a part of the circumference (substantially one quarter of the circumference) when viewed from the long axis of the cylinder. .
[0048]
In the RF coil 100, two coil elements adjacent to each other along the circumferential direction are formed so as to partially overlap each other. Further, the areas of the overlapping portions between the coil elements are all formed to be equal. In addition, the area of the overlap portion is arranged, for example, to be equal to about 10% of the area of each coil element.
Further, in the overlap portion, the distance between the respective coil elements is formed substantially equal.
[0049]
Two adjacent coil elements 101 and 102 form a pair, and similarly, two adjacent coil elements 103 and 104 also form a pair. The two coil elements of each pair are connected to a common ground potential at the overlap.
[0050]
FIG. 4 shows a state where the RF coil 100 shown in FIG. 1 is expanded. FIG. 4A shows a state where the paired coil elements 101 and 102 are expanded, and FIG. 4B shows a state where the paired coil elements 103 and 104 are expanded. I have. In FIGS. 4A and 4B, circuit elements, for example, capacitors arranged in the respective coil elements are also shown.
The RF coil 100 has a decoupling circuit connected to the coil loop of each coil element for reception. However, the decoupling circuit is omitted in FIGS. 4A and 4B.
[0051]
As shown in FIG. 4A, two coil elements are connected to a common ground potential at an overlapping portion between the coil elements 101 and 102. The coil element 101 is connected to the terminal _Tc1 from the ground via the capacitor C1. Further, the coil element 102 is connected to the terminal _Tc2 from the ground point via the capacitor C2. Thus, in the coil elements 101 and 102, the signal output units are provided near the respective ground points. The RF excitation signals received by the coil elements 101 and 102 are input to a preamplifier (not shown) via the terminals _Tc1 and _Tc2 , and the RF excitation signal amplified by the preamplifier is output to the data collection unit 24.
[0052]
Similarly, as shown in FIG. 4B, in the overlapping portion between the coil elements 103 and 104, the two coil elements are connected to a common ground potential. The coil element 103 is connected to the terminal _Tc3 from the ground via the capacitor C3. Further, the coil element 104 is connected to the terminal _Tc4 from the ground point via the capacitor C4. As described above, in the coil elements 103 and 104, the signal output units are provided near the respective ground points.
The RF excitation signal received by each of the coil elements 103 and 104 is amplified by a preamplifier (not shown) via a signal output unit provided in each coil element, and output to the data collection unit 24.
[0053]
As described above, in the receiving RF coil constituting the magnetic resonance imaging apparatus of the present embodiment, two adjacent coil elements form a pair, and the two coil elements of each pair overlap each other. Have a common ground potential. As a result, the potential difference between adjacent coils is reduced, and damage to the circuit element due to the potential difference between the coils can be prevented, and the stability of the coil element can be improved. Further, by sharing the ground potential of adjacent coil elements, a balun for outputting a magnetic resonance signal from each coil element is not required, and connection of a signal output unit in each coil element can be simplified. .
[0054]
Furthermore, in the RF coil 100 of the present example, a pair of coil elements forming a pair are arranged so as to overlap each other, and the area of the overlapping portion is equal in all the coil elements. Since each coil element is arranged along a cylindrical surface so as to be approximately 10% of the area of the coil element, the electromagnetic induction caused by the mutual inductance between adjacent coil elements has the same polarity. Are opposite, so that they cancel each other out and have no effect.
[0055]
Next, the overall operation of the magnetic resonance imaging apparatus of the present embodiment having the above-described configuration will be described.
[0056]
This pulse sequence for magnetic resonance imaging includes a so-called spin echo (SE: Spin Echo) method, a gradient echo (GRE: GRADIENT ECHO) method, a fast spin echo (FSE: Fast Spin Echo) method, and a fast recovery SE (Fast Recovery Spin Echo). ) Method and echo planer imaging (EPI: Echo Planar Imaging) method.
[0057]
Here, among the pulse sequences of the respective imaging methods, the pulse sequence of the SE method will be described with reference to FIG.
FIG. 5A shows a sequence of 90 ° pulses and 180 ° pulses for RF excitation in the SE method, and the driving signal DR1 applied by the RF driving unit 22 to the transmitting coil (or the transmitting / receiving coil) of the RF coil unit 214. Is equivalent to
FIGS. 5B, 5C, 5D, and 5E show the sequence of the slice gradient Gs, the readout gradient Gr, the phase encode gradient Gp, and the spin echo MR, respectively. The pulses of the gradient Gr and the phase encode gradient Gp correspond to the drive signal DR2 applied to the gradient coil unit 213 by the gradient drive unit 23.
[0058]
As shown in FIG. 5A, a 90 ° pulse is applied to the transmission coil of the RF coil unit 214 by the RF drive unit 22 to excite the spin by 90 °. At this time, as shown in FIG. 5B, a slice gradient pulse Gs is applied to the gradient coil unit 213 by the gradient driving unit 23, and selective excitation is performed for a predetermined slice.
As shown in FIG. 5A, after a predetermined time from the 90 ° excitation, a 180 ° pulse is applied to the transmission coil of the RF coil unit 214 by the RF driving unit 22, and the 180 ° excitation, that is, spin inversion is performed. Done. Also at this time, as shown in FIG. 5B, the gradient driving unit 23 applies a slice gradient pulse Gs to the gradient coil unit 213, and selectively inverts the same slice.
[0059]
As shown in FIGS. 5C and 5D, the readout gradient pulse Gr and the phase encode gradient pulse Gp are supplied to the gradient coil unit 213 by the gradient driving unit 23 during the period between the 90 ° excitation and the spin inversion. Is applied.
Then, spin dephase is performed by the readout gradient pulse Gr, and phase encoding of the spin is performed by the phase encode gradient pulse Gp.
[0060]
After the spin reversal, as shown in FIG. 5B, the readout gradient pulse Gr is applied to the gradient coil unit 213 by the gradient driving unit 23, and the spin is rephased in response to the readout gradient pulse Gr. As shown in ()), a spin echo MR is generated. The signal intensity of the spin echo MR becomes maximum at a time point after TE (echo time) from the 90 ° excitation.
The spin echo MR is collected by the data collection unit 24 as view data. Then, the view data collected by the data collection unit 24 is output to the data processing unit 31 of the operator console 30.
[0061]
In the data processing unit 31, data input from the data collection unit 24 is stored in a memory, and a data space is formed in the memory. The data processing section 31 performs a two-dimensional inverse Fourier transform on the data in the two-dimensional Fourier space to generate (reconstruct) an image of the test site of the subject 40.
[0062]
As described above, according to the receiving RF coil of the present embodiment and the magnetic resonance imaging apparatus using the same, the ground potential of the adjacent coil elements is made common, and the signal output section of the RF excitation signal is provided near the ground potential. Is provided, a high voltage difference between adjacent coil elements can be eliminated, circuit elements can be prevented from being damaged due to the high voltage difference, and stabilization of electrical characteristics of the entire RF coil can be improved.
In addition, since a pair of coil elements forming a pair are arranged so as to overlap each other, the magnitude of the electromagnetic induction caused by the mutual inductance between the adjacent coil elements is the same, and the polarities are opposite. There is no effect due to cancellation.
[0063]
It should be noted that the RF coil according to the present invention is not limited to the above-described configuration, but may have another configuration. That is, by providing a signal output portion of the RF excitation signal near the virtual ground potential on the coil forming the loop, the voltage difference between the coil elements can be reduced, thereby preventing the circuit element on the coil from being damaged. It is possible to stabilize the electrical characteristics of the RF coil.
[0064]
FIG. 6 shows another configuration example of the receiving RF coil of the present invention. The receiving RF coil 100a of the present embodiment includes four single-loop coil elements 101, 102, 103, and 104 having a substantially cylindrical shape, similarly to the RF coil 100 shown in FIG. Two adjacent coil elements are arranged so as to overlap each other.
As shown in the drawing, in this configuration example, the signal output unit of the RF coil 100a is provided substantially at the intermediate points A1 to A4 in the long axis direction of the cylindrical shape formed by the single loop coil elements 101 to 104. .
[0065]
FIG. 6 shows an example of a potential distribution in a long axis direction of a cylindrical shape in each coil element. As shown in the figure, in the major axis direction of the coil element, the potential of the RF excitation signal is distributed according to, for example, a sine wave. A virtual ground potential appears at both ends and intermediate points in the long axis direction of the cylindrical shape. For this reason, as shown in FIG. 6, by providing the signal output portion of the RF excitation signal at substantially the midpoint in the long axis direction, the voltage difference between the coil elements in the signal output portion can be kept small, and the high voltage Breakage of the circuit element due to the difference can be prevented. This can improve the stability of the electrical characteristics of the RF coil.
[0066]
【The invention's effect】
As described above, according to the RF coil of the present invention and the magnetic resonance imaging apparatus constituted by using the same, the ground potential of a pair of adjacent coil elements is set to the respective coil elements constituting the RF coil. By providing a signal output portion for the RF excitation signal near the common ground potential, the voltage difference between adjacent coils near the signal output portion can be reduced, and damage to circuit elements due to a high voltage difference can be prevented. . The same effect can be achieved by providing a signal output section near the virtual ground potential of the RF excitation signal in the coil element on the loop.
Therefore, according to the RF coil of the present invention and the magnetic resonance imaging apparatus using the same, there is an advantage that the electrical characteristics of the RF coil can be stabilized.
[Brief description of the drawings]
FIG. 1 is a configuration diagram illustrating an embodiment of a magnetic resonance imaging system including a magnetic resonance imaging apparatus according to the present invention.
FIG. 2 is a configuration diagram illustrating an example of a receiving RF coil used in the magnetic resonance imaging apparatus of the present embodiment.
FIG. 3 is a sectional view showing a specific configuration of a receiving RF coil.
FIG. 4 is a developed view showing a specific configuration of a receiving RF coil.
FIG. 5 is a waveform chart showing signal waveforms at the time of imaging by the magnetic resonance imaging apparatus of the present embodiment.
FIG. 6 is a configuration diagram showing another configuration example of the receiving RF coil of the present invention.
[Explanation of symbols]
10 MRI system, 20 MRI apparatus, 21 magnet system, 211 bore, 212 main magnetic field magnet section, 213 gradient coil section, 214 RF coil section, 22 RF drive section, 23 gradient drive section, 24 data collection unit, 25 control unit, 26 cradle, 30 operator console, 31 data processing unit, 32 image database, 33 image processing database, 34 operation unit, 35 display unit, 40 unit Specimen, 100, 100a ... RF coil for reception, 101 to 104 ... single loop coil element.

Claims (10)

Four single-loop coil elements that are substantially cylindrical,
A ground connection portion in which the adjacent single loop coil elements form a pair by two, and the two single loop coil elements in each pair are commonly connected to a ground potential at a location adjacent to each other;
An RF coil having a signal output portion provided near the ground connection portion. 2. The RF coil according to claim 1, wherein the single loop coil elements are arranged so as to overlap each other so that mutual inductance between two adjacent coil elements is substantially zero. 2. The RF coil according to claim 1, wherein in the single-loop coil element, two adjacent coil elements overlap each other, and an area of the overlapping portion is equal to an area of an overlapping portion between other adjacent coil elements. 3. . 2. The RF coil according to claim 1, wherein in the single-loop coil element, two adjacent coil elements overlap each other, and an area of the overlapped portion is about 10% of an area of the entire coil element. 3. 2. The RF coil according to claim 1, wherein in the single loop coil element, an interval between two adjacent coil elements is formed equal to an interval between other two adjacent coil elements. 3. A magnetic resonance imaging apparatus that generates an image of a subject based on a magnetic resonance signal received by applying a high-frequency magnetic field to a subject to be imaged under a static magnetic field and a gradient magnetic field,
An RF coil for receiving the magnetic resonance signal excited by the subject by the high-frequency magnetic field,
The RF coil includes four single-loop coil elements each having a substantially cylindrical shape,
A ground connection portion in which the adjacent single loop coil elements form a pair by two, and the two single loop coil elements in each pair are commonly connected to a ground potential at a location adjacent to each other;
A magnetic resonance imaging apparatus having a signal output unit provided near the ground connection unit. 7. The magnetic resonance imaging apparatus according to claim 6, wherein the single-loop coil elements are arranged so as to overlap each other so that mutual inductance between two adjacent coil elements is substantially zero. 7. The magnetic resonance according to claim 6, wherein in the single loop coil element, two adjacent coil elements overlap each other, and an area of the overlapping portion is formed to be equal to an area of an overlapping portion between the other adjacent coil elements. Imaging device. 7. The magnetic resonance imaging system according to claim 6, wherein the single-loop coil element is formed such that two adjacent coil elements overlap each other, and an area of the overlapping portion is about 10% of an area of the entire coil element. apparatus. 7. The magnetic resonance imaging apparatus according to claim 6, wherein in the single loop coil element, an interval between two adjacent coil elements is formed to be equal to an interval between other two adjacent coil elements.

Images