JP2010119744A - Magnetic resonance imaging system and rf (radio frequency) coil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To confirm at least part of positional relationship between a predetermined region specified by a positioning MR image 403 and coil conductors 101-104 included in an RF receiving coil 14. <P>SOLUTION: The positional relationship between the position of the region specified by the positioning MR image 403 and the position of at least part of the coil conductors 101-104 of the RF receiving coil 14 is shown by a positioning light 17 or a display 34. The region in the positioning MR image 403 is specified by automatically detecting the predetermined region included in the positioning MR image or by operator's locating a region marker 403 in a position corresponding to the region of the positioning MR image. According to an MRI SYSTEM, in creating a phase image, a coil conductor of the RF receiving coil 14 affecting the phase image is located away from internal organs as an object of analysis. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a magnetic resonance imaging system (MRI) and an RF coil (Radio Frequency Coil), and in particular, the position of a predetermined region included in an MR image taken by a magnetic resonance imaging apparatus and the RF coil. The present invention relates to a magnetic resonance imaging apparatus showing a positional relationship of coil conductors to be used or an RF coil used in the magnetic resonance imaging apparatus.

  The magnetic resonance imaging apparatus irradiates a subject in a static magnetic field space with an electromagnetic wave, thereby exciting a proton spin in the subject by a nuclear magnetic resonance phenomenon. A scan is performed to obtain the generated magnetic resonance signal. Then, an MR image is generated for the tomographic plane of the subject based on the magnetic resonance signal obtained by the scan.

Each pixel (or each voxel) of the MR image obtained by such a magnetic resonance imaging apparatus becomes a complex image having the magnitude and angle value (complex number) of the rotating magnetization vector. Normally, an intensity image obtained by imaging only the intensity component of a complex NMR signal is used as an MR image, but it is also known to reconstruct a phase image obtained by imaging the rotation angle (phase) of a magnetization vector. ing. In particular, due to recent advances in MRI technology, the speeding up of imaging has progressed and the non-uniformity of the magnetic field has become sufficiently small, so that the disturbance generated in the phase image is not reduced, and the phase image can be used sufficiently. It has become.

  Such a phase image may be used to distinguish a predetermined organ region from other tissue regions. For example, when the proton density is a measurement target, the signal value is high in a portion where the proton density is sufficiently high, so that the influence of noise is relatively low and the phase becomes uniform. Conversely, when the proton density is low, the influence of noise becomes large and the phase becomes random. For this reason, in the phase image, the phase is uniform in the myocardial region, whereas the phase randomly changes in the background region such as the lung field. Using this property, the boundary between the myocardium and the lung field can be discriminated with high accuracy, and the heart region can be automatically extracted.

  In addition, for example, when imaging the heart or abdomen of a subject, there is a problem that body movement artifacts (artifacts) are generated due to body movements such as breathing movements and heartbeat movements, and the quality of the image is lowered. One method to solve this problem is to correct the excitation cross section of the subject in real time according to the change in the position of the diaphragm, for example, in imaging under normal breathing, and always measure the magnetic resonance signal from the same cross section By doing so, the deterioration of the image due to the body movement artifact is prevented. In addition, the acquired navigator echo is used to change the imaging sequence or select the imaging data, thereby preventing deterioration in image quality due to body movement artifacts.

  As a method for detecting the position of the diaphragm used in these techniques, a method is known in which the movement of the diaphragm is tracked using navigator echoes, and respiratory synchronization and gating are performed using the obtained navigator data. As an analysis method of navigator data, for example, the Ahn method, the LSQ method, the edge detection method, and the like are known (see, for example, Patent Document 1 and Non-Patent Document 1).

Japanese Patent Laid-Open No. 10-277010 (see, for example, paragraphs 0002 to 0006) JP 2002-315734 A JP-A-7-143974 JP 2006-204330 A Yiping P. Du, ManojkumarSaranathan, and Thomas K. F. Foo. “An Accurate, Robust, and Computationally Efficient Navigator Algorithm for MeasuringDiaphragm Positions”, JOURNAL OFCARDIOVASCULAR MAGNETIC RESONANCE Vol.6, No.2, pp. 483-490, 2004

  However, such useful phase images are affected by the magnetic field inhomogeneity generated around the coil conductor of the RF receiving coil, resulting in degradation of the image quality in the vicinity of the coil conductor of the RF receiving coil. The accuracy of the automatic detection process may be adversely affected.

FIG. 16A shows a phase image related to navigator phase information when there is no coil conductor of the receiving coil near the lung-liver boundary 911, and FIG. 16B shows a receiving coil near the lung-liver boundary 913. A phase image when there is a coil conductor is shown. In both figures, the vertical axis indicates the position along the body axis (z-axis) of the subject (patient) 40, the horizontal axis indicates time, and the luminance corresponds to the phase. As shown in FIGS. 16A and 16B, noise is not generated so much in the vicinity of the boundary 911 in FIG. 16A, whereas noise appears in the vicinity of the boundary 913 in FIG. I understand that. That is, in the vicinity of the boundary 913 in FIG. 16B, the luminance value does not become the luminance corresponding to the organ at the location, and the luminance value is disturbed, compared to the vicinity 911 in FIG. . Such noise adversely affects the accuracy of the automatic detection processing of the diaphragm position. This hinders obtaining a stable analysis result of navigator data during navigator data analysis.

Furthermore, it is not easy to design an RF receiver coil to reconstruct an equally high quality image in all regions of the RF receiver coil, even when generating an intensity image, especially positioned near the periphery of the RF receiver coil. It is known that the image quality of the image of the part of the subject is inferior to the image quality of the image of the part positioned near the center of the RF receiving coil.

  Therefore, an object of one embodiment of the present invention is to indicate a positional relationship between a predetermined region specified by a positioning MR image and a coil conductor of an RF receiving coil.

  It is another object of the present invention to indicate an arrangement position of an RF receiving coil in which the coil conductor of the RF receiving coil does not approach a predetermined region that the operator desires to observe or is an object of automatic detection processing.

  Another aspect of the present invention provides a magnetic resonance imaging system capable of capturing an MR image only when the RF receiving coil is mounted at a position that does not adversely affect a predetermined region specified by the positioning MR image. The purpose is to do.

  Another aspect of the present invention provides a magnetic resonance imaging system capable of capturing a phase image only when an RF receiving coil is mounted at a position that does not adversely affect a predetermined region specified by a positioning MR image. The purpose is to do.

  Another aspect of the present invention provides a magnetic resonance imaging system capable of imaging MR images by positioning a predetermined region specified by a positioning MR image at a position where the RF receiving coil is considered to be reconstructed with the highest image quality. The purpose is to do.

  Another object of the present invention is to provide an RF receiving coil in which the position of the coil conductor of the RF receiving coil can be confirmed by a positioning MR image.

In one aspect of the present application, a magnetic resonance imaging system that generates an image of a subject based on a magnetic resonance signal generated from the subject,
An RF coil that includes a coil conductor, is attached to a predetermined part of the subject, and receives a magnetic resonance signal;
An MR image generation unit that generates a positioning MR image showing an internal structure of the subject based on a magnetic resonance signal generated from the subject to which the RF coil is attached;
Indicating means for indicating a position of a specified region included in the positioning MR image or a position to move the RF coil;
A magnetic resonance imaging system is provided.

In another aspect of the present application, the magnetic resonance imaging system includes a static magnetic field coil that generates a static magnetic field, and a magnetic resonance imaging apparatus that includes a gradient magnetic field coil that generates a gradient magnetic field,
A table for placing the subject and moving the subject;
Control means for controlling the table so that the predetermined part of the subject is arranged at a position suitable for imaging the positioning MR image in the static magnetic field space;
Further comprising
The pointing means is a positioning light that indicates a position of the specified region or a position to move the RF coil;
After the positioning MR image is generated, the control means controls the table so that the position of the specified region indicated by the positioning light or the position of the RF coil is to be moved. .

In another aspect of the present application, the control unit controls the table so that the RF coil indicated by the positioning light is arranged at a position to be moved after the positioning MR image is generated.
The RF coil has a mark for associating the RF coil with a position indicated by the positioning light.

  As a result, the system indicates the positional relationship between the position of the region specified by the positioning MR image and the position of at least a part of the coil conductor of the RF coil, and the system operator can grasp the positional relationship between the two. In another aspect of the present application, the RF coil attached to a predetermined part of the subject is a surface coil. In one aspect of the present invention, an RF coil that receives a magnetic resonance signal for generating the positioning MR image is an RF coil different from the surface coil.

In another aspect of the present application, a magnetic resonance imaging system that generates an image of a subject based on a magnetic resonance signal generated from the subject,
An RF coil that includes a coil conductor, is attached to a predetermined part of the subject, and receives a magnetic resonance signal;
An MR image generating unit that generates a positioning MR image showing an internal structure of the subject based on a magnetic resonance signal received by the RF coil;
Position information acquisition means for acquiring position information of an area specified in the positioning MR image;
Distance specifying means for specifying a distance between the specified region and at least a part of the coil conductor;
A magnetic resonance imaging system is provided.

In another aspect of the present application, the position information of the specified area is position information of an area marker positioned corresponding to a predetermined anatomical feature included in the positioning MR image.

In one aspect of the present application, the region in the positioning MR image is identified by automatically detecting a predetermined anatomical feature included in the positioning MR image, or by an operator at a position corresponding to the region in the positioning MR image. This is done by positioning the area marker.

In another aspect of the present application, the magnetic resonance imaging system includes a camera that images the RF coil attached to the subject;
A display device for displaying the positioning MR image;
Means for displaying the identified region as a region marker on the positioning MR image;
Further comprising
The display device displays a display indicating the region marker on a camera image of the RF coil photographed by the camera.

In another aspect of the present application, the magnetic resonance imaging system includes a camera that images the RF coil attached to the subject;
Coil conductor detection means for detecting the position of at least a part of the coil conductor from a camera image captured by the camera,
A display device for displaying the positioning MR image;
The display device displays a display corresponding to at least a part of the detected coil conductor on the positioning MR image.

In another aspect of the present application, the position of the coil conductor of the RF coil on the camera image may be detected automatically by detecting the coil conductor of the RF coil included in the camera image, or the RF coil included in the camera image This is done by the operator positioning the coil indicator at a position corresponding to the coil conductor.

In another aspect of the present application, the RF coil has a housing, and the housing has an element mark having a predetermined color at a position corresponding to the position of the at least part of the coil conductor. And
The coil conductor detection means detects the position of at least a part of the coil conductor by identifying the predetermined color included in the camera image.

In another aspect of the present application, the coil conductor detection unit detects a position of at least a part of the coil conductor by performing matching with a prestored image model indicating the characteristics of the RF coil.

In another aspect of the present application, the magnetic resonance imaging system includes a static magnetic field coil that generates a static magnetic field, and a magnetic resonance imaging apparatus that includes a gradient magnetic field coil that generates a gradient magnetic field,
A table for placing the subject and moving the predetermined part of the subject;
Further comprising
The camera is attached to the magnetic resonance imaging apparatus at a position separated from the main body of the magnetic resonance imaging apparatus so as not to affect the static magnetic field in the magnetic resonance imaging apparatus.

In another aspect of the present application, the magnetic resonance imaging system further includes a display device that displays the positioning MR image,
The RF coil has a housing, and the housing has an element mark formed of a substance detectable by an MR image at a position corresponding to at least a part of the coil conductor.
The display device displays a positioning MR image including a display corresponding to the element mark.

In another aspect of the present application, the positioning MR image is an image of a coronal section.

In another aspect of the present application, in the magnetic resonance imaging system, the element mark is formed of a substance exhibiting a predetermined frequency characteristic,
The MR image generation unit includes a positioning MR image including the element mark formed of a material exhibiting the predetermined frequency characteristic, and a positioning MR image indicating an internal structure of the subject not including the element mark. Generate.

In another aspect of the present application, the positioning MR image is a phase image,
The magnetic resonance imaging system further comprises image processing means for processing the phase image,
The pixel values of the pixels constituting the phase image correspond to the phase,
The image processing device specifies a position of at least a part of the coil conductor.

In another aspect of the present application, the position of at least a part of the coil conductor is automatically detected by detecting the influence of the coil conductor of the RF coil included in the phase image, or the RF coil included in the phase image. This is done by the operator positioning the coil indicator at the position where the influence of the coil conductor is generated.

In one aspect of the present application, a display corresponding to the coil conductor of the RF coil specified by the phase image is displayed at a corresponding position in the positioning MR image.

In one aspect of the present application, the positional relationship between the position of the region specified by the positioning MR image and the position of at least a part of the coil conductor of the RF coil is indicated by a positioning light.

  In one aspect of the present application, the positional relationship between the position of the region specified by the positioning MR image and the position of at least a part of the coil conductor of the RF coil is indicated by the display device.

In another aspect of the present application, the image processing apparatus includes:
In the phase image, specify a region where the dispersion of pixel values is high,
The portion showing the high dispersion is recognized as the position of at least a part of the coil conductor.

In another aspect of the present application, the element mark is formed of a substance exhibiting a predetermined frequency characteristic,
The RF coil comprises a loop coil formed of the coil conductor;
The loop coil is tuned to tune to at least two of the predetermined frequency and the 1H frequency.

In another aspect of the present application, the specified region is a diaphragm located between the lung and the liver of the subject.

In another aspect of the present application, the RF coil is attached to a predetermined part of a subject and receives a magnetic resonance signal generated from the subject,
A housing,
A coil conductor disposed in the housing;
With
The housing has an element mark at a position corresponding to the position of at least a part of the coil conductor,
When imaged by the magnetic resonance imaging apparatus, a positioning MR image including the element mark and a positioning MR image showing the internal structure of the subject not including the element mark can be reconstructed by selection. is there,
An RF coil is provided.

In another aspect of the present application, the RF coil includes a loop coil formed of the coil conductor,
The element mark is made of a material exhibiting a predetermined frequency characteristic,
The loop coil is tuned to tune to at least two of the predetermined frequency and the 1H frequency.

In another aspect of the present application, the RF coil includes at least four rectangular loop coils formed of the coil conductor,
Forming at least two pairs of loop coils in which the at least two rectangular loop coils overlap each other in a direction perpendicular to the direction of the body axis of the subject;
The at least two loop coil pairs are arranged overlapping in the direction of the body axis;
The at least four rectangular loop coils overlap each other at at least one point;
The element mark is
At least two loop coils located on both sides in the direction perpendicular to the direction of the body axis across the at least one point are arranged.

  According to the present invention, it is possible to confirm the positional relationship between at least a portion of the region specified by the positioning MR image and the coil conductor included in the RF coil.

  According to another aspect of the present invention, the position of at least a part of the coil conductor included in the RF coil and the position of the predetermined area displayed in the positioning MR image can be adjusted to have a predetermined positional relationship. it can.

  According to another aspect of the present invention, only when the position of at least a part of the coil conductor included in the RF coil and the position of the predetermined region displayed in the positioning MR image have a predetermined positional relationship, Imaging can be performed, and the image quality of a predetermined area displayed in the MR image can be improved.

  According to another aspect of the present invention, only when the position of at least a part of the coil conductor included in the RF coil and the position of the predetermined region displayed in the positioning MR image have a predetermined positional relationship, the phase image is displayed. Shooting can be performed, and the image quality of a predetermined area displayed in the phase image can be improved.

  According to another aspect of the present invention, a magnetic resonance imaging system capable of capturing an MR image by positioning a predetermined region specified by a positioning MR image at a position where the RF receiving coil is considered to be reconstructed with the highest image quality. Can be provided.

  According to another aspect of the present invention, it is possible to provide an RF receiving coil in which the position of the coil conductor of the RF receiving coil can be confirmed by a positioning MR image.

<Device configuration>
FIG. 1 is a configuration diagram showing the configuration of a magnetic resonance imaging system (MRI system) according to an embodiment of the present invention. This system is an example of an embodiment of the present invention. As shown in FIG. 1, the MRI system 1 includes an MRI apparatus 2 and an operation console 3. Here, the MRI apparatus 2 includes a static magnetic field magnet (magnet) unit 12, a gradient coil (coil) unit 13, an RF receiving coil 14, an RF transmitting / receiving coil 142, a table 15, a positioning light 17, and a rear The camera 18 described in detail in FIG. The operation console 3 includes an RF drive unit 22, a gradient drive unit 23, a data collection unit 24, a control unit 30, a storage unit 31, an operation unit 32, a data processing unit 33, and a display unit 34. Have

  As shown in FIG. 1, the MRI apparatus 2 includes a static magnetic field space 11 in which an imaging slice region in the subject 40 is accommodated. Then, the MRI apparatus 2 irradiates the imaging region of the subject 40 accommodated in the static magnetic field space 11 in which the static magnetic field is formed based on a control signal from the operation console 3, and magnetically radiates from the imaging region. A scan to acquire the resonance signal is performed.

  In the present embodiment, the MRI apparatus 2 has an imaging sequence for obtaining magnetic resonance signals generated in the imaging region of the subject 40 as imaging data, and a navigator for acquiring magnetic resonance signals generated in the navigator region of the subject 40 as navigator data. Repeat the sequence.

  The static magnetic field magnet unit 12 is provided to form a static magnetic field in the static magnetic field space 11 in which the subject 40 is accommodated. The static magnetic field magnet unit 12 is a horizontal magnetic field type, and is a superconducting magnet (z direction) along the body axis direction (z direction) of the subject 40 placed in the static magnetic field space 11 in which the subject 40 is accommodated. (Not shown) forms a static magnetic field. In addition to the horizontal magnetic field type, the static magnetic field magnet unit 12 may be a vertical magnetic field type or a permanent magnet.

  The gradient coil unit 13 forms a gradient magnetic field in the static magnetic field space 11 so that the magnetic resonance signal received by the RF receiving coil 14 or the RF transmitting / receiving coil 142 has three-dimensional position information. The gradient coil unit 13 has three systems of gradient coils to form three types of gradient magnetic fields: a slice selection gradient magnetic field, a read gradient magnetic field, and a phase encoding gradient magnetic field.

  In the preferred embodiment of the present invention, the RF receiving coil 14 is a reception-only RF surface coil disposed so as to surround the body of the subject 40, and the RF transmitting / receiving coil 142 is disposed in a cylindrical magnet bore. The RF coil is disposed adjacent to the gradient coil unit 13. The RF transmission / reception coil 142 transmits an RF pulse, which is an electromagnetic wave, to the subject 40 based on a control signal from the control unit 30 in the static magnetic field space 11 in which a static magnetic field is formed by the static magnetic field magnet unit 12 to generate a high frequency. Create a magnetic field. As a result, the spin of protons in the imaging slice region of the subject 40 is excited. The RF transmitter / receiver coil 142 or the RF receiver coil 14 receives, as a magnetic resonance signal, an electromagnetic wave generated when the spin of protons in the imaging slice region of the excited subject 40 returns to the original magnetization vector (vector). . In the preferred embodiment of the present invention, the positioning MR image described later in FIG. 6 and the like, the phase profile described later in FIG. 15 and the positioning phase image described later in FIG. 14 are included in the magnetic resonance signal received by the RF transmitting / receiving coil 142. Based on. However, any or all of these positioning MR images, phase profiles, and positioning phase images may be generated based on magnetic resonance signals received by the RF receiving coil 14 instead of the RF transmitting / receiving coil 142. Note that the RF reception coil 14 is not dedicated to reception but may be capable of both transmission and reception, and either the RF coil 14 or the RF transmission / reception coil 142 receives a magnetic resonance signal based on the RF pulse transmitted by the RF coil 14. Any or all of the positioning MR image, the phase profile, and the positioning phase image may be generated.

  FIG. 2 is an external view showing a specific example of the RF reception coil 14 (including both the reception-dedicated RF coil and the transmission / reception RF coil) used in the MRI apparatus 2 of the present embodiment. In the preferred embodiment of the present invention, the RF receiving coil 14 has a resin casing 143, and the coil conductor is accommodated in the casing 143. In a preferred embodiment of the present invention, the housing 143 has a frame corresponding to a rectangular loop coil, and the material forming the housing is present near the center of each loop coil 101-104. Instead, they are cavities 151-154. In the preferred embodiment of the present invention, the RF receiver coil 14 shown in FIG. 2 is curved so as to be in close contact with the chest of the subject 40, and is elastic in consideration of the difference in the body shape of the subject 40. It has sex. In the preferred embodiment of the present invention, one RF receiving coil 14 is provided for the front of the chest of the subject 40 and one is provided for the back of the chest, for a total of two RF receiving coils 14 of the subject 40. It is attached to. In the preferred embodiment of the present invention, the RF receiving coil 14 described above is used. However, the RF receiving coil 14 used in the present invention is not limited to this, and the subject 40 is not limited thereto. It may be an RF receiving coil such as a single loop coil disposed on the chest or a cylindrical RF receiving coil that entirely surrounds the head of the subject 40.

FIG. 3 is a conceptual diagram showing the coil conductors 101 to 104 included in the RF receiving coil 14 shown in FIG. As shown in FIG. 3, the RF receiving coil 14 of this example is constituted by four loop coils 101, 102,. Each of the loop coils 101 to 104 is configured as a single loop, and is arranged such that adjacent coil conductors (coil elements) overlap each other along the body axis direction (z direction) of the subject 40. Has been. Two loop coils adjacent in the direction perpendicular to the body axis (x direction) are also arranged so as to overlap each other. In this embodiment, the loop coils 101 to 104 are arranged so that all the loop coils 101 to 104 overlap each other at the center point 105. Due to this overlap, the loop coils 101 to 104 are decoupled from each other. In addition, the ground potential is shared by each pair of loop coils arranged adjacent to each other, and the positions of the grounds of the loop coils 101 to 104 virtually coincide with each other. Coil stability is improved. Further, since the RF receiving coil 14 is composed of a four-channel loop coil, the RF excitation signal can be received in a desired phase direction. 2 and 3, two pairs of loop coils (101 and 102 and 103 and 104) in which loop coils are arranged in a direction perpendicular to the body axis of the subject 40 are provided in the body axis direction. Although an example in which the coils are arranged is shown, a six-channel RF examination coil in which three pairs of loop coils are arranged so as to overlap in the body axis direction may be used.

  Returning to FIG. 1 again, the table 15 has a cradle 16 on which the subject 40 is placed. The table 15 moves the subject 40 placed on the cradle 16 between the inside and the outside of the static magnetic field space 11 based on a control signal from the control unit 30.

  A positioning light 17 is provided on the end face of the MRI apparatus 2 and normally irradiates the imaging center part of the subject 40 to be positioned at the scan center SC of the MRI apparatus 2 at the time of positioning. Since the distance DL (FIG. 5) of the Z-direction component from the positioning light 17 to the scan center SC is constant, the desired object 40 that has been moved by the cradle 16 and positioned by the positioning light 17 (setting: setting) is desired. The imaging center portion of the MRI apparatus 2 can be moved to the scan center SC of the MRI apparatus 2 to take an MR image.

  The operation console 3 controls the MRI apparatus 2 to scan the subject 40 and generates an MR image of the subject 40 based on the magnetic resonance signal obtained by the scan performed by the MRI apparatus 2. At the same time, the generated MR image is displayed.

  The RF driving unit 22 drives the RF receiving coil 14 or the RF transmitting / receiving coil 142 to form a high-frequency magnetic field in the static magnetic field space 11 and a gate modulator (not shown) and an RF power amplifier (not shown). ) And an RF oscillator (not shown). Based on the control signal from the control unit 30, the RF drive unit 22 modulates the RF signal from the RF oscillator into a signal having a predetermined timing (timing) and a predetermined envelope using a gate modulator. Then, the RF signal modulated by the gate modulator is amplified by the RF power amplifier and then output to the RF receiving coil 14 or the RF transmitting / receiving coil 142.

  The gradient driving unit 23 drives the gradient coil unit 13 based on a control signal from the control unit 30 to generate a gradient magnetic field in the static magnetic field space 11. The gradient drive unit 23 includes three systems of drive circuits (not shown) corresponding to the three systems of gradient coils of the gradient coil unit 13.

  The data collecting unit 24 includes a phase detector (not shown) and an analog / digital converter (not shown) in order to collect magnetic resonance signals received by the RF receiving coil 14 or the RF transmitting / receiving coil 142. The data collection unit 24 detects the phase of the magnetic resonance signal from the RF reception coil 14 or the RF transmission / reception coil 142 by using the phase detector with the output of the RF oscillator of the RF drive unit 22 as a reference signal, and converts it to an analog / digital converter. Output. Then, the magnetic resonance signal, which is an analog signal phase-detected by the phase detector, is converted into a digital signal by the analog / digital converter and output to the data processing unit 33.

  The control unit 30 includes a computer and a program that causes each unit to execute an operation corresponding to a predetermined scan using the computer. And the control part 30 is connected to the operation part 32 mentioned later, processes the operation signal input into the operation part 32, the table 15, the positioning light 17, the camera 18, RF drive part 22, gradient drive part 23 and a control signal is output to each part of the MRI apparatus including the data collecting part 24 to control each part. The positioning light 17 may be simply turned on in addition to the on / off control performed by the control unit 30. Further, the control unit 30 controls the data processing unit 33 and the display unit 34 based on an operation signal from the operation unit 32 in order to obtain a desired image.

  In the present embodiment, the control unit 30 controls the RF driving unit 22 and the gradient driving unit 23 to cause the scanning unit 2 to execute a navigator sequence and an imaging sequence. The control unit 30 controls the imaging sequence performed by the scanning unit 2 based on the navigator data obtained by executing the navigator sequence, and controls the data processing unit 33 to process the imaging data. To do.

  The storage unit 31 includes a computer and a program that causes the computer to execute predetermined data processing. And the memory | storage part 31 memorize | stores the magnetic resonance signal before the image reconstruction process collected by the data collection part 24, the image data by which the image reconstruction process was carried out by the data processing part 33 mentioned later, etc.

  The operation unit 32 includes an operation device (device) such as a keyboard and a mouse. An operator inputs operation data, an imaging protocol (protocol), and the like using the operation unit 32, and sets an area for executing an imaging sequence and an area for executing a navigator sequence. The operation unit 32 outputs the operation data, the imaging protocol, and data related to the setting area to the control unit 30.

  The data processing unit 33 includes a computer and a memory that stores a program that executes predetermined data processing using the computer, and performs data processing based on a control signal from the control unit 30.

  FIG. 4 is a block diagram showing a configuration of the data processing unit 33 in the embodiment according to the present invention. As illustrated in FIG. 4, the data processing unit 33 includes an image reconstruction unit (image generation unit) 331, a phase image analysis unit 336, and an image processing unit 335. The phase image analysis unit 336 includes a phase profile generation unit 332, a phase correction unit 333, and a position detection unit 334. The data processing unit 33 executes various types of data processing when the computer operates according to a program stored in the storage unit 31 and loaded into the memory.

  The image reconstruction unit 331 uses, as raw data, a magnetic resonance signal obtained as imaging data by performing an imaging sequence for the imaging region of the subject 40, thereby obtaining an MR image of the imaging region of the subject 40. Reconstruct the image. Further, the positioning MR image and the positioning phase image, which will be described in detail later, are also generated by the image reconstruction unit 331 using the magnetic resonance signal received by the RF receiving coil 14 or the RF transmitting / receiving coil 142. That is, in a preferred embodiment of the present invention, in the execution of the imaging sequence by the MRI apparatus 2, the RF transmission / reception coil 142 transmits an RF pulse to the imaging region, and the magnetic resonance signal generated in the imaging region is transmitted to the RF transmission / reception coil. A positioning MR image, a phase profile, and a positioning phase image are generated based on the imaging data collected by the reception of the 142. Then, the image reconstructed slice image is output to the display unit 34.

  The image processing unit 335 processes the MR image generated by the image reconstruction unit 331 and a camera image described later, and displays the processing result image on the display unit 34. In addition, input data input to the image to be processed is stored in the storage unit 31 as position information.

  For example, the phase profile generation unit 332 uses the magnetic resonance signal obtained as navigator data by the navigator sequence performed before the execution of the imaging sequence for the imaging region of the subject 40 as raw data, so that the subject A phase profile for 40 navigator regions is generated. That is, the navigator data collected by the data collection unit 24 is subjected to a one-dimensional Fourier transform, and a phase profile is generated by plotting the relationship between the phase P and the position Z of the data subjected to the one-dimensional Fourier transform. .

  The phase correction unit 333 corrects the phase profile generated by the phase profile generation unit 332.

  The position detector 334 detects the position of the coil conductor of the RF receiving coil 14. In the present embodiment, the position detection unit 334 analyzes the degree of dispersion of the phase profile in the phase profile of navigator data that has been subjected to the one-dimensional Fourier transform by the phase profile generation unit 332, and has a dispersion higher than a predetermined threshold value. It is recognized that a coil conductor exists in the portion shown.

  Further, as described above, the phase value in the phase image has a property that it varies depending on the type of tissue, and in a preferred embodiment, the position detection unit 334 applies a threshold process or the like to the phase image, The position of a predetermined anatomical feature or region in the subject 40, such as the position of the diaphragm at the boundary between the lung and the liver, is detected.

  Returning to FIG. 1 again and continuing the description, the display unit 34 is configured by a display device such as a display, and displays an image on the display screen based on a control signal from the control unit 30. The display unit 34 displays, for example, an image of input items for which operation data is input to the operation unit 32 by the operator on the display screen. The display unit 34 displays various image information such as a slice image and a three-dimensional image of the subject 40 generated by the data processing unit 33.

<First embodiment>
In the first embodiment, the table 15 is controlled so that the positioning light 17 illuminates the region specified by the positioning MR image or the position where the RF receiving coil 14 should be moved, and is specified by the positioning MR image. The positional relationship between the position of the region and the coil conductor of the RF receiving coil 14 is shown. The specific processing procedure will be described below.

1-1. The RF receiving coil 14 is attached to the subject 40. The RF receiving coil 14 is attached by a doctor, an engineer, a nurse, or the like (hereinafter referred to as “medical worker”). The subject 40 is laid on the cradle 16, the position of the cradle 16 is controlled, and positioning is performed such that the positioning light 17 illuminates the center of the RF receiving coil 14, for example. At this time, instead of the center of the RF receiving coil 14, a specific location on the body surface of the subject 40 that can be observed through the cavity of the RF receiving coil 14 may be selected as a positioning point.

1-2. Under the control of the control unit 30, the subject 40 is moved into the static magnetic field space of the MRI apparatus 2, and a point (hereinafter simply referred to as “positioning point”) positioned by the positioning light 17 is positioned at the scan center SC. The moving amount of the cradle 16 at this time is −DL. In the example of FIG. 5, DL = 110 cm, and the cradle 16 moves 110 cm in the direction of the head of the subject 40.

1-3. In this state, a positioning MR image, that is, a localizer image is taken, and the positioning MR image is displayed on the display unit 34 by a known method. The positioning MR image is an MR image used in a known graphic prescription method. That is, in order to acquire signals from the region of interest to the operator via the MRI system, acquisition to be performed, including entering parameters such as field of view, spacing and thickness along with the desired image orientation and position. It is necessary to first define the law by the operator. In the preferred embodiment of the present invention, the graphic defining method is one of the functions provided by the image processing unit 335 of FIG. 4, and the positioning MR image along the coronal section is sent to the scan center SC at the time of photographing. An MR image in which the positioning point of the positioned subject 40 is located at the center is obtained.

The graphic defining method is a method that allows an operator to perform the definition using a graphic method. Typically, to perform the graphic definition method, a plurality of reference positioning MR images are first acquired, and then the operator defines these positioning MR images as points, lines, boxes or other shapes. A mark is added and the mark can be manipulated until the desired regulation is achieved. Provided is a regulation interface that allows an operator to operate in an efficient manner so that the operator can create an accurate regulation (see, for example, Patent Document 2).

In this example, three-dimensional localizer imaging is performed, and an operator can display the positioning MR image along each of the axial section, coronal section, and sagittal section on the display unit 34 as desired, and perform the above-mentioned graphic definition. .

1-4. FIG. 6 is a diagram showing an example of an acquired MR image of a coronal section. In this positioning MR image 401, the operator designates an area where it is desirable that the coil conductor is not located. In this example, the boundary between the lung and the liver is marked by the region marker 403 on the positioning MR image 401 along the coronal section. The operator clicks the start point on the display screen using the pointing device such as the mouse of the operation unit 32, drags it to the end point, and releases the click, thereby releasing a desired rectangular area on the display screen. And the region marker 403 can be positioned at a desired position on the positioning MR image 401. Through the marking operation using the series of operation units 32, the image processing unit 335 of the console 3 specifies the coordinate value of the area marker 403 and stores it in the storage unit 31. In the illustrated example, the area marker 403 is a rectangle, and the control unit 30 acquires the coordinate values of two vertices at diagonal positions of the rectangle and stores them in the storage unit 31. In other embodiments, since the size of the target organ is almost constant, only the coordinate value of the center position of the rectangle is stored.

In another example, when the operator clicks the target organ on the positioning MR image 401, the region of the target organ can be specified by a known edge detection process or segmentation process.

1-5. In the positioning MR image 401, the distance DM along the Z-axis between the center (X _A , Z _A ) of the area marker 403 and the scan center SC is calculated, and the movement amount DA of the table 15 is determined. In the example of FIG. 5, the distance DM of the Z direction component of the center (position of the target organ) A of the area marker 403 with respect to the scan center SC is −1 cm, and the positioning light 17 is at the center of the area marker 403. The moving amount DA of the table 15 necessary for illuminating the position of the corresponding subject 40 is DA = DL-DM. In the example of FIG. 5, DA = 110 cm − (− 1 cm) = 111 cm, and the cradle 16 moves 111 cm in the direction of the foot of the subject 40.

1-6. When the cradle 16 is moved under the control of the control unit 30 according to the determined movement amount DA of the table 15, the positioning light 17 causes the subject 40 and the RF reception corresponding to the position of the region marker 403 marked in the positioning MR image 401. The position of the coil 14 will be illuminated.

1-7. Thereby, the medical staff can confirm the positional relationship between the marker position corresponding to the position of the predetermined anatomical feature or region designated by the operator and the position of the coil conductor.

1-8. That is, when the coil conductor is sufficiently away from the position illuminated by the positioning light 17 (in this example, it is determined whether or not it is 3 cm or more away from the center of the frame of the RF receiving coil 14), the positioning point is set. Returning to the scan center SC, MR imaging is resumed. At this time, the movement amount for moving the cradle 16 is -DA, that is, DM-DL. In the example of FIG. 5, the cradle 16 moves 111 cm in the direction of the head of the subject 40. In the preferred embodiment of the present invention, the width of the frame of the housing 143 of the RF receiver coil 14 that houses the plurality of loop coils 101-104 is designed to match the preferred distance when positioned above. (Ie, a width of 3 cm × 2 = 6 cm), the medical worker can easily determine whether or not to move the RF receiving coil 14. That is, when the frame of the RF receiving coil 14 is illuminated by the positioning light 17, it is possible to determine that the RF receiving coil 14 needs to be moved, otherwise it is not necessary to move. In another example, the area where the influence of the coil conductor is large and the movement of the RF receiving coil 14 is strongly recommended and the area where the influence is not large but recommended to move are displayed in an identifiable manner.

In the preferred embodiment of the present invention, the need for such movement of the RF receiver coil 14 can be made automatically. That is, the MRI apparatus 2 includes an optical sensor 19 (not shown) in the vicinity of the positioning light 17, and the optical sensor 19 is configured to detect light reflected by the positioning light 17. On the other hand, as shown in FIG. 7, on the frame of the housing 143 of the RF receiving coil 14, other RF reception is performed in a region 161 of ± 3 cm (that is, a region in which the coil conductor affects) sandwiching the center of the frame. The surface of the coil housing, the skin of the subject, the test wear of the subject, and the reflectance of the positioning light 17 are designed to be distinguishable. For example, the area is processed to reflect light with a high reflectance, and the reflected light data detected by the optical sensor is sent to the data processing unit 33, and the value of the reflected light is compared with a threshold value. .

  When the value of the reflected light is higher than the threshold value, the data processing unit 33 determines that the RF receiving coil 14 needs to be moved, and displays on the display unit 34 to instruct the operator to move the RF receiving coil 14. I do. If the value of the reflected light is lower than the threshold value, the data processing unit 33 determines that there is no need to move the RF receiving coil, returns the positioning point to the scan center SC, and uses the RF receiving coil 14 for navigator. The attached MR image is taken. Further, not only MR images with a navigator using the RF receiving coil 14 but also various types of MR images designated by the operator can be acquired.

In one embodiment of the present application, in order to perform automatic detection / tracking processing of the position of the diaphragm, a phase image is newly captured, and the captured phase image is processed by a known method. In another embodiment, in order to perform segmentation processing of a predetermined organ, a phase image is newly captured, and the captured phase image is segmented by a known method. In another embodiment of the present application, the imaging for the phase image is not newly performed, the phase image is reconstructed from the MR signal obtained in step 1-3, and the diaphragm is based on the reconstructed phase image. The automatic detection / tracking process and the segmentation process of a predetermined organ are performed.

1-9. When there is a coil conductor in the portion indicated by the positioning light 17, the medical worker manually shifts the coil position of the RF receiving coil 14. In another embodiment of the present invention, the RF receiving coil 14 is automatically shifted without using a manual method using a known method such as Japanese Patent Application Laid-Open No. 7-143974 (Patent Document 3).

  In the above example, the center of the RF receiving coil is designated as the positioning point, but instead, specific points of the RF receiving coil 14 such as the upper end and the lower end of the RF receiving coil may be designated as the positioning point. In addition, the positioning MR image 401 was photographed, and the table 15 was returned so that the positioning light 17 illuminates the area specified by the positioning MR image 401 after the subject 40 is taken out of the static magnetic field space 11. Thus, the table 15 can be moved so that the positioning light 17 illuminates a position where a specific point of the RF receiving coil 14 such as the center point, upper end, and lower end of the RF receiving coil should be moved.

  That is, in step 1-1, the positioning light 17 is adjusted and positioned so that the positioning light 17 illuminates a specific point of the RF receiving coil such as the center of the RF receiving coil 14 to which the subject 40 is attached. Specify a point. The RF receiving coil used in this example is the RF receiving coil 14 shown in FIG. 2, and the center line of the coil conductor is located at the center of the RF receiving coil 14.

Steps 1-2 to 1-4 perform the same process as in the above example.

In step 1-5, in the positioning MR image 401, the distance between the Z coordinate value (Z _A ) of the center (X _A , Z _A ) of the region marker 403 and the positioning point (in this case, the center of the positioning MR image 401) is calculated. Is done. If the absolute value of this distance is equal to or greater than a predetermined value (3 cm, which is a recommended distance from the coil conductor in this example), the area 403 specified by the positioning MR image 401 is sufficiently separated from the coil conductor. Since the determination can be made, the position of the RF receiving coil 14 is not reset, and the MR imaging process is continued.

When the absolute value of the distance DM of the Z direction component between the center position A of the area marker 403 and the scan center SC is equal to or smaller than a predetermined value, the distance to be moved by the RF receiving coil 14 is calculated. The recommended separation distance, that is, the distance DR recommended to separate the target organ from the coil conductor is 3 cm, and the movement amount DA to be moved on the table 15 is DA = DL-DM ± DR. In the example of FIG. 5, DA = 110 cm − (− 1 cm) ± 3 cm = 114 cm or 108 cm.

Whether the sign of DR is positive or negative may be selected by the operator or automatically by the system. In this case, in order to reduce the amount of movement of the coil, the movement destination of the coil is set to R1 when the value of DM is positive, and the movement destination of the coil is set to R2 when the value of DM is negative. Is preferred.

When the cradle 16 is moved under the control of the control unit 30 according to the movement amount DA of the table 15 determined in step 1-6, the positioning light 17 illuminates the position where the center of the RF receiving coil 14 should be moved. It becomes. The healthcare worker manually shifts the coil position according to the positioning light 17. Thereby, the RF receiving coil 14 can be rearranged at a position where the coil conductor does not affect the area specified by the positioning MR image 401.

After the RF receiver coil 14 is rearranged, the initially set positioning point is returned to the scan center SC, and MR image capturing is resumed. Alternatively, if necessary, the positioning point is reset, the newly set positioning point is moved to the scan center SC, MR image capturing is resumed, and the diaphragm position is automatically detected and tracked according to a known method. Various types of processing such as processing, segmentation processing of a predetermined organ, and various types of MR images designated by an operator are acquired.

The first embodiment has been described above. Of the various changes and additions described in the other embodiments, changes and additions that can be applied to the first embodiment can be applied to the first embodiment. .

<Second embodiment>
In the second embodiment, the RF receiver coil 14 attached to the subject 40 is photographed by the camera 18, and the region marker 403 extracted from the positioning MR image 401 described in the first embodiment is superimposed on the photographed camera image. . The specific processing procedure will be described below.

2-1. The subject 40 is placed on the table 15 and the RF receiving coil 14 is attached to the subject 40.

2-2. The subject 40 wearing the RF receiving coil 14 is imaged by the camera 18. The photographing by the camera 18 may be performed with the cradle 16 completely out of the main body of the MRI apparatus 2 or at the time of positioning with the positioning light 17. In a preferred embodiment of the present invention, the camera 18 is a general digital camera that includes an image sensor that converts visible light into a digital signal and can output a digital image. In another embodiment, the camera 18 shoots a light beam having a wavelength longer than that of visible light such as infrared rays. By selecting a material forming the casing 143 of the RF receiving coil 14, the camera 18 is placed inside the casing 143. The coil conductors 101-104 can be photographed.

In the preferred embodiment of the present invention, as shown in FIG. 1, the camera 18 is positioned in the vicinity of the positioning light 17 from the static magnetic field region so as not to affect the static magnetic field of the MRI apparatus 2. Positioned at a distance. In addition, the camera image captured by the camera 18 is configured to capture an area including a predetermined area with the positioning point as the center, and specify the predetermined area corresponding to the positioning MR image 401 with the positioning point as the center. Yes. In this example, 40 cm × 40 cm is specified.

Specifically, the positioning point is specified with the subject 40 mounted on the RF receiving coil 14, and the table 15 is moved so that the positioning point moves directly below the camera (of the known camera and the positioning light 17. Move a distance). Thereby, it is possible to prevent the image captured by the camera from being skewed with respect to the positioning MR image 401, that is, the position of the two is not shifted. Further, by adjusting the height (in the y direction) of the cradle 16 during imaging by the camera, the camera 18 and the plane corresponding to the RF receiving coil 14, the body surface of the subject 40, or the coronal cross section of the positioning MR image 401. The distance can be constant, and a predetermined area corresponding to the positioning MR image 401 can be easily specified in the camera image. A method for associating a camera image with a fluoroscopic image is known (for example, Patent Document 4), and those skilled in the art can implement various modifications in this respect.

A camera image photographed by the camera and a 40 cm × 40 cm camera image corresponding to the positioning MR image 401 with the positioning point as the center are stored in the storage unit 31 in the form of digital data. FIG. 8 is a conceptual diagram illustrating an example of a captured camera image.

2-3. Similar to Step 1-2 in the first embodiment, the subject 40 is moved into the static magnetic field space of the MRI apparatus 2 under the control of the control unit 30, and the positioning point is positioned at the scan center SC.

2-4. As in step 1-3 of the first embodiment, the positioning MR image 401 is photographed, and the positioning MR image 401 is displayed on the display unit 34 by a known method.

2-5. Similar to step 1-4 of the first embodiment, in the obtained positioning MR image 401, an area where it is desirable that the coil conductor is not located is specified by the area marker 403.

2-6. The area 403 identified in step 2-5, that is, the area marker 403 is also displayed on the camera image 410 stored in the storage unit 31 in 2-2. FIG. 9 is a conceptual diagram showing an example of the camera image 410 in a state where the area marker 403 is displayed on the camera image 410. In the preferred embodiment of the present invention, the position information (for example, the start point and end point) of the (rectangular) area marker 403 marked in step 2-5 is subjected to similarity conversion and displayed at the corresponding position on the camera image 410. When the camera image 410 corresponding to the positioning MR image 401 having the same scale ratio is used, the area marker 403 can be displayed without the similarity conversion process. In another embodiment, the positioning MR image 401 is superimposed on the camera image 410 after the contrast of the positioning MR image 401 is corrected and an image other than the region marker 403 is processed to be inconspicuous. Accordingly, the medical staff can visually confirm the positional relationship between the position of the area marker 403 corresponding to the position of the predetermined area designated by the operator and the position of the coil conductor. In the preferred embodiment of the present invention, the width of the frame 413 of the housing 143 of the RF receiving coil 14 that houses the plurality of coil loops 101-104 is designed to match the distance that is preferably positioned as described above. Thus, the operator can easily determine whether or not the RF receiving coil 14 needs to be moved. That is, when the area marker 403 is superimposed on the frame 413 of the RF receiving coil 14, it can be determined that the RF receiving coil 14 needs to be moved, and otherwise it is not necessary to move. In another example, the housing of the RF receiving coil 14 includes a region where the influence of the coil conductor is large and the movement of the RF receiving coil 14 is strongly recommended, and a region where the influence is not large but is recommended if possible. A camera image 410 displayed on the display unit 34 is displayed so as to be identifiable by a predetermined color (red, yellow, etc.) (FIG. 7, area 161) and whether or not the area marker 403 is superimposed on these areas. It can be easily judged by looking at In another example, a gauge indicating the actual distance or an icon having a size corresponding to the distance (3 cm) preferred to be spaced apart as described above is provided on the display 34 and the operator can use these tools. Then, it is determined whether or not the RF receiving coil 14 needs to be moved. The distance that is desired to be separated, that is, the recommended distance between the region specified by the operator in the positioning MR image 401 and at least a part of the coil conductor of the RF receiver coil 14 is the type of the RF receiver coil 14 used in the system. At the stage of setting, the RF reception coil type and the recommended separation distance are automatically specified using a correspondence table. In the preferred embodiment of the present application, this recommended separation value can be changed by the operator.

2-7. If it is determined in step 2-6 that there is no need to move the RF receiving coil 14, the MR image acquisition process is continued with the positioning point positioned at the scan center SC, and the above diaphragm Various processes such as an automatic position detection / tracking process and a predetermined organ segmentation process are performed.

2-8. When it is determined in step 2-6 that the RF receiving coil 14 needs to be moved, the operator confirms the necessary coil moving amount in the camera image 410.

Specifically, when the operator moves the RF receiving coil 14 by using the gauge described in Step 2-6, the coil conductor of the RF receiving coil 14 is identified in the positioning MR image 401. Therefore, the RF receiving coil 14 can be moved manually or automatically according to the movement amount confirmed after the subject 40 is moved out of the MRI apparatus 2. In the preferred embodiment of the present invention, a gauge is stamped on the side of the cradle 16, and the operator can move the RF receiving coil 14 by referring to the gauge.

In another embodiment, a necessary movement amount confirmed by the operator using the gauge on the camera image 410 is input using the operation unit 32. The control unit 30 calculates the amount of movement of the table 15 in the same manner as in the first embodiment, and controls and moves the table 15 so that the positioning light 17 illuminates the position where the RF receiving coil 14 should be rearranged. .

In another embodiment, the required movement amount of the RF receiving coil 14 is automatically calculated by the image processing unit 335. As shown in FIG. 10, in the preferred embodiment of the present invention, a coil indicator 421 (coil indicator) is provided that indicates the position of the coil conductor. The operator can determine the position of the coil conductor by dragging and dropping the coil indicator 421 on the camera image 410.

When the coil indicator 421 is dropped, the image processing unit 335 calculates the distance in the direction along the z axis between the region marker 403 and the coil indicator 421. In this example, since the diaphragm extending in the x direction of the coronal section is the target organ, the distance between the organ and the coil conductor extending in the x direction becomes a problem, and the distance in the z direction is determined. When the organ extending in the direction is the target organ, the distance between the organ and the coil conductor extending in the z direction becomes a problem, and the distance in the x direction is determined. Furthermore, in the case of an organ that extends in both the x and z directions, such as the kidney, it is preferable to calculate the distance in both directions. Further, for example, when the organ in the inner ear is the target organ, the same distance measurement is performed on the sagittal section.

The distance between the area marker 403 and the coil indicator 421, that is, the distance between the area specified by the positioning MR image 401 and at least a part of the coil conductor of the RF receiving coil 14 is a predetermined distance (the coil conductor affects the phase image). When the image processing unit 335 is away from the given range (± 3 cm in this example) or more, the image processing unit 335 sends a message to the display unit 34 indicating that the RF receiver coil 14 does not need to be rearranged. indicate.

When the distance between the area marker 403 and the coil indicator 421 is not a predetermined distance, or when the operator particularly desires the rearrangement of the RF receiving coil 14, the image processing unit 335 can drag and drop the area marker 403. Put it in a state. When the operator moves the area marker 403 up or down on the camera image 410 and the area marker 403 is separated from the center of the coil conductor by 3 cm (a distance recommended to be separated from the coil conductor) or more, the color of the area marker 403 Changes (eg, changes from yellow to blue). When the area marker 403 is dropped on the camera image 410 in this state, the amount of movement to move the RF receiving coil 14 is determined by the position of the area marker 403 before the movement and the position of the area marker 403 after the movement. In another example, the image processing unit 335 automatically calculates the position where the region marker 403 is separated from the coil conductor by the recommended separation distance (3 cm), and the operator moves 2 above or below the coil conductor to display the 2 By selecting the preferred one of the two area markers 403, the position where the RF receiving coil 14 should be rearranged can be designated. Further, the two-party selection is not performed, and the image processing unit 335 may automatically select only one of the two candidates with the smaller movement amount.

From the position of the coil indicator 421 relative to the positioning point and the amount of movement of the RF receiver coil 14, the amount of movement of the table 15 that illuminates the position where the position light 17 should move the RF receiver coil is calculated. The cradle 16 is moved under the control of the control unit 30 in the same manner as described above. As in the case of the first embodiment, the medical staff manually shifts the coil position according to the positioning light 17. Thereby, the RF receiving coil 14 can be rearranged at a position where the coil conductor does not affect the area specified by the positioning MR image 401.
After the RF receiver coil 14 is rearranged, the initially set positioning point is returned to the scan center SC, and MR image capturing is resumed. Also, if necessary, the positioning points are reset, the newly set positioning points are moved to the scan center SC, MR imaging is resumed, and the diaphragm position is automatically detected and tracked according to a known method. Various types of processing such as processing, segmentation processing of a predetermined organ, and various types of MR images designated by an operator are acquired.

In another embodiment, the recognition process of the RF receiving coil 14 described later in the third embodiment is performed on the camera image 410, and the image processing unit 335 detects the position of the coil conductor closest to the area marker 403. Then, the image processing unit 335 calculates the distance between the area marker 403 and the detected coil conductor, and if the distance is 3 cm or more, the processing is continued.

If the distance is less than 3 cm, an element icon 423 (Element Icon, not shown) corresponding to the coil conductor is displayed on the camera image 410 and can be dragged and dropped as in the case of the area marker 403. Similar to the case of the area marker 403, the moving distance of the table 15 is calculated according to the distance before and after the element icon 423 is dropped, and the positioning light 17 is connected to the RF receiving coil 14 by the control of the control unit 30. Move to a position that illuminates the destination.

  Although the second embodiment has been described above, among the various modifications described in the other embodiments, changes applicable in the second embodiment can be applied to the second embodiment.

<Third embodiment>
In the third embodiment, the RF receiving coil 14 attached to the subject is photographed by the camera 18, and a display corresponding to at least a part of the coil conductor of the RF receiving coil 14 specified by the photographed camera image is displayed as the positioning MR image 401. Superimposed on the display. Identification of the coil conductor in the camera image is performed manually or automatically. The specific processing procedure will be described below.

  Steps 3-1 to 3-4 of the third embodiment are the same as steps 2-1 to 2-4 of the second embodiment.

3-5. Similar to steps 1-4 of the first embodiment and steps 2-5 of the second embodiment, the region marker 403 identifies a region where the coil conductor is preferably not located in the obtained positioning MR image 401. . However, as will be described later, since the positional relationship between the specific organ and the coil conductor in the positioning MR image 401 can be confirmed without the area marker 403, Step 3-5 is not an essential step in the third embodiment. .

3-6. A display element icon 423 indicating at least part of the coil conductor of the RF receiving coil 14 specified by the camera image is displayed on the positioning MR image 401 in which the area marker 403 is specified.

  Specifically, as shown in FIG. 11, the coil indicator 421 indicating the position of the coil conductor described in 2-8 of the second embodiment is positioned in the MR image 401 (the area marker 403 is not particularly necessary). The operator can specify the distance between the target organ displayed on the positioning MR image 401 and the coil conductor using a gauge similar to the gauge described in Step 2-6 of the second embodiment. It is possible to determine whether or not the RF receiving coil 14 needs to be rearranged and a necessary amount of movement of the RF receiving coil 14.

  In the preferred embodiment of the present invention, the distance between the region specified by the positioning MR image 401 and at least a part of the coil conductor of the RF receiving coil 14 in the same manner as described in Step 2-8 of the second embodiment. Is automatically calculated. That is, the image processing unit 335 calculates the distance in the direction along the z axis between the region marker 403 and the coil indicator 421 identified in step 3-5.

The distance between the area marker 403 and the coil indicator 421, that is, the distance between the area specified by the positioning MR image 401 and at least a part of the coil conductor of the RF receiving coil 14 is a predetermined distance (the coil conductor affects the phase image). When the image processing unit 335 is away from the given range (± 3 cm in this example) or more, the image processing unit 335 sends a message to the display unit 34 indicating that the RF receiver coil 14 does not need to be rearranged. indicate. When the distance between the area marker 403 and the coil indicator 421 is not a predetermined distance, or when the operator particularly desires to reposition the RF receiving coil 14, the image processing unit 335 displays the coil indicator on the positioning MR image 401. 421 can be dragged and dropped. When the operator moves the coil indicator 421 up or down on the positioning MR image 401 and the coil indicator 421 is separated from the area marker 403 by 3 cm (a recommended distance away from the coil conductor) or more, the coil indicator is displayed. The color of 421 changes (for example, changes from yellow to blue). When the coil indicator 421 is dropped on the positioning MR image 401 in this state, the amount of movement to move the RF receiving coil 14 is determined by the position of the coil indicator 421 before the movement and the position of the coil indicator 421 after the movement. Is done. Note that the moving destination of the coil indicator 421 may be automatically determined in the same manner as the automatic movement processing of the area marker 403 described in 2-8 of the second embodiment.

The amount of movement of the table 15 that illuminates the position where the position light 17 should move the RF receiving coil is calculated from the position before the movement of the coil indicator 421 relative to the positioning point and the amount of movement of the coil indicator 421. The cradle 16 is moved under the control of the control unit 30 in the same manner as described in the example. As in the case of the first embodiment, the medical staff manually shifts the coil position according to the positioning light 17. Thereby, the RF receiving coil 14 can be rearranged at a position where the coil conductor does not affect the area specified by the positioning MR image 401. After the RF receiver coil 14 is rearranged, the initially set positioning point is returned to the scan center SC, and MR image capturing is resumed. Also, if necessary, the positioning points are reset, the newly set positioning points are moved to the scan center SC, MR imaging is resumed, and the diaphragm position is automatically detected and tracked according to a known method. Various types of processing such as processing, segmentation processing of a predetermined organ, and various types of MR images designated by an operator are acquired.

In another embodiment, the coil indicator 421 is not specified by the operator but is automatically detected from the camera image 410 by a known image recognition process. Specifically, an element mark 161 (FIG. 7) having a predetermined color is arranged on the housing 143 of the RF receiving coil 14 at a position corresponding to at least a part of the coil conductor. The processing unit 335 detects the position of the coil conductor by identifying the predetermined color area included in the camera image 410. The predetermined color is preferably a color that can be sufficiently distinguished from the skin of the subject 40, the wound, and an organ that may be exposed from the wound, the test clothes, and the other surface of the RF receiving coil 14.

In the example of FIG. 12, the element mark is arranged at a position on the housing corresponding to all the coil conductors included in the RF receiving coil 14 (position corresponding to the region 161 in FIG. 7), and the image processing unit 335. After correcting the recognition result, the image of the element icon 423 is displayed at the corresponding position in the positioning MR image 401.

In another example, four element marks having a predetermined shape are arranged at four points where an inner frame formed in a cross shape and a square outer frame intersect, that is, end points on the upper, lower, left and right sides of the inner frame. By detecting the four element marks, an element icon 423 having a shape corresponding to all or part of the element marks in FIG. 12 or the element marks can be displayed on the positioning MR image 401. In another example, an element mark having a predetermined shape is arranged at four vertices or two diagonal points of the outer frame, and the element icon 423 in FIG. 12 is entirely detected by detecting the element mark. Alternatively, a part can be displayed on the positioning MR image 401. In this case, the image processing unit 335 specifies the position of the inner frame based on the information specifying the type of the RF receiving coil 14 input by the operator and the position information of the outer frame.

The image of the element icon 423 can be moved on the positioning MR image 401 in the same manner as when the coil indicator 421 is used. In this specification, the element mark is a mark indicating the position of the coil conductor on the housing 143 of the RF receiving coil, and the element icon is formed by recognizing the element mark or the RF receiving coil 14 itself. The display controlled by the image processing unit 335, and the coil indicator is a display controlled by the image processing unit 335 used when the operator indicates the position of the coil conductor on the image. The image processing unit 335 uses a part or a plurality of parts or all of the element icon 423 in the same manner as the coil indicator 421 described above, and confirms the recommended separation distance described above. Arrangement position determination processing can be performed.

In another embodiment, the image model of the RF receiving coil 14 used in the system is stored in a state where the image processing unit 335 can be used in advance, and the image processing unit stores the characteristics of the RF receiving coil stored in advance. By searching the camera image 410 for a matching area with an image model indicating the position of the image model, the position of at least a part of the RF receiving coil 14 in the camera image 410 or the coil conductor included therein is determined.

In still another embodiment, symbols, characters, graphics, and the like indicating the type of the RF receiving coil 14 are arranged in a predetermined region of the casing 143 of the RF receiving coil 14, and the image processing unit 335 includes the casing 143. The position of the predetermined region in the camera image 410 is specified, a known OCR process is executed, the type of the RF receiving coil 14 is specified, and the image of the corresponding element icon 423 stored in advance is stored in the positioning MR image 401. Display at the corresponding position.

  Although the third embodiment has been described above, among various modifications described in the other embodiments, the changes applicable in the third embodiment can be applied to the third embodiment.

<Fourth embodiment>
In the fourth embodiment, unlike the third embodiment, the position of the coil conductor is specified not by the camera image 410 but by the positioning MR image 401, and the display corresponding to at least a part of the coil conductor of the RF receiving coil 14 is positioned. The image is superimposed on the MR image 401 and displayed. The specific coil conductor is specified manually or automatically in the positioning MR image 401. The specific processing procedure will be described below.

Steps 4-1 to 4-3 of the fourth embodiment are performed in the same manner as steps 1-1 to 1-3 of the first embodiment, and a positioning MR image 401 showing the internal structure of a predetermined part of the subject 40 is obtained. To be acquired. However, the casing 143 of the RF receiving coil 14 used at this time is coated or housed with a substance exhibiting special frequency characteristics as an element marker, and the coil conductor of the RF receiving coil 14 in the positioning MR image 401 is applied. At least a part of the position can be detected.

  In a preferred embodiment of the present invention, the material exhibiting special frequency characteristics is any one of Na-23, P-31, C-13, O-17, Xe-129, Li-7, and He-3. , At least one of each loop coil 101-104 of the RF receiver coil 14 is tuned to tune to two frequencies, a frequency of 1H (proton) and a frequency of the substance, and optionally an image of the substance. It is possible to collect a positioning MR image 401 including the above and a positioning MR image 401 including no image of the substance.

  In another embodiment, a strong NMR signal such as baby oil is generated at a position that does not hinder the medical staff from confirming the MR image, such as the two vertices forming the diagonal of the outer frame of the RF receiver coil 14. It is also possible to arrange the substance to be detected and detect the position of the coil conductor. In such a case, it is possible to remove a portion on which the substance used for detection of the coil conductor is displayed from the MR image used when the medical staff makes a diagnosis.

  In still another embodiment, the element mark can be detachably disposed on the RF receiving coil 14 by means of a hook-and-loop fastener, adhesive, fitting, screwing, etc., and the element mark is only detected when the coil conductor is detected. Can be arranged in the RF receiving coil 14.

4-4. The position of at least a part of the coil conductor of the RF receiving coil 14 is specified in the acquired positioning MR image 401.

Similarly to the case described with reference to FIG. 12 in step 3-6 of the third embodiment, the element mark 161 of the housing 143 of the RF receiving coil 14 is attached to all the coil conductors included in the RF receiving coil 14. The image processing unit 335 performs correction processing on the recognition result, and then corresponds to the positioning MR image 401. An element icon 423 is displayed at the position.

The image of the element icon 423 can be moved on the positioning MR image 401 as in the case of the third embodiment. The image processing unit 335 can use the element icon 423 to perform the above-described recommended separation confirmation process and the rearrangement position determination process of the RF receiving coil 14.

In another example, the element icon 423 is displayed in an identifiable manner on the positioning MR image 401 so that the operator can manually locate the coil conductor by dropping the coil indicator 421 or the like. .

  Although the fourth embodiment has been described above, among various modifications described in the other embodiments, changes applicable in the fourth embodiment can be applied to the fourth embodiment.

<Fifth embodiment>
In the fifth embodiment, unlike the fourth embodiment, it is not necessary to arrange the element marker 161 in the RF receiving coil 14 when detecting the coil conductor in the positioning MR image 401. In the fifth embodiment, the coil conductor The position of the coil conductor is specified by analyzing the influence on the phase image. The position of the coil conductor is specified manually or automatically. The specific processing procedure will be described below.

Steps 5-1 to 5-3 of the fifth embodiment are performed in the same manner as steps 1-1 to 1-3 of the first embodiment, and a positioning MR image 401 showing the internal structure of a predetermined part of the subject 40 is obtained. To be acquired. However, the positioning MR image 401 acquired at this time is a positioning phase image in which each pixel corresponds to the phase information, and the selection region includes a region close to the coil conductor of the RF receiving coil 14 that is greatly influenced by the coil conductor. Selected. This is because the portion 431 where the influence of the coil conductor on the phase image is large is limited to the vicinity of the coil conductor, as shown in the conceptual diagram of the axial cross section of the subject in FIG. In a preferred embodiment of the present invention, this positioning phase image is generated based on the magnetic resonance signal received by the RF receiving coil 14 or the RF transmitting / receiving coil 142.

5-4. The position of at least a part of the coil conductor of the RF receiving coil 14 is specified in the acquired positioning MR image 401.

  In one embodiment of the present invention, the position of the coil conductor is specified in a format similar to the method described in FIG. 10 of the second embodiment. That is, the operator observes the positioning phase image, specifies the line where the phase is disturbed, and specifies the position of the coil conductor by dropping the coil indicator 421 at that position (FIG. 14).

In another embodiment of the present invention, the position of the coil conductor is automatically recognized and identified. In this case, the positioning phase image need not be displayed on the display unit 34. Here, the phase profile generation unit 332 performs a one-dimensional Fourier transform on the navigator data acquired by executing the navigator sequence. Then, the phase profile generation unit 332 of FIG. 4 generates a phase profile by plotting the relationship between the phase in the navigator data subjected to the one-dimensional Fourier transform and the position in the z-axis direction in the navigator area NA. Here, FIG. 15A is a diagram showing a phase profile in which navigator data is subjected to a one-dimensional Fourier transform and a phase is plotted along a straight line 425 shown in FIG. 12 in an embodiment according to the present invention. In the preferred embodiment of the present invention, the straight line 425 is a straight line parallel to the Z axis and passing through the center (X _A , Z _A ) of the area marker 403 (ie, x = X _A ). By generating the phase profile with such a straight line, even when the RF receiving coil 14 is attached to the subject 40 in a slightly inclined state, the calculation of the distance between the specified region 403 of the subject and the coil conductor is inclined. The adverse effects can be minimized. Note that generating the phase profile along the straight line 425 is merely an example, and other straight lines may be employed. For example, it is possible to generate a phase profile with two straight lines along the Z axis located at a predetermined distance from the right end and the left end of the RF receiving coil 14 and detect the position of the coil conductor in each of the two straight lines. In this case, the inclination of the RF receiving coil can also be detected. Further, for example, the phase profile along the Z axis may be integrated over the width of the region marker 403 in the X direction to generate an integrated phase profile, and the detection process of the high dispersion section W described later may be performed.

In FIG. 15A, the vertical axis represents the phase P, and the horizontal axis represents the position in the z-axis direction in the navigator area. In the figure, a region having a small phase P represents a lung phase, and a region having a large phase P represents a liver phase. As necessary, the phase correction unit 333 corrects the phase profile.

  As shown in FIG. 15A, in the phase profile, there is a section W in which the dispersion of plot points is high. It can be considered that the high dispersion in the section W is due to the influence of the coil conductor of the RF receiving coil 14. Assuming that the phase profile along the straight line 425 of the RF receiving coil 14 having four loop coils 101-104 shown in FIG. 12 is created, the straight line 425 crosses the coil conductor at three points, and thus the dispersion of plot points is high. Section W appears at three places. However, the RF receiving coil 40 is virtually not attached to the subject 40 so that the region of interest corresponding to the region marker 403 is positioned in the vicinity of the coil conductor near the upper end or the lower end of the RF receiving coil 14. The influence of the coil conductor near the upper end and the coil conductor near the lower end of the RF receiving coil 14 is not significant. Therefore, in the preferred embodiment of the present invention, the phase profile is generated only for a predetermined section (for example, SC ± 10 cm) sandwiching the scan center SC, thereby speeding up the calculation process.

In the preferred embodiment of the present invention, as shown in FIG. 15B, the position detector 334 analyzes the dispersion of the phase profile along the Z position. Then, the dispersion profile of this phase is compared with a predetermined dispersion threshold S, and a section W having a dispersion value higher than the dispersion threshold S is specified. In this example, the center position of the section W is recognized as the center of the coil conductor. In the preferred embodiment of the present invention, since the phase profile is generated only for a predetermined section, there is one coil conductor to be detected by the dispersion profile. However, when there are a plurality of coil conductors in a predetermined section or when the predetermined section is not limited, a plurality of sections W having a dispersion value higher than the dispersion threshold S are detected. Of the plurality of detected sections W, the section W closest to the Z coordinate (Z _A ) of the region marker 403 is specified as the position of the coil conductor in question.

Based on such recognition processing, the phase image analysis unit 336 can detect the positions of all or part of the coil conductors of the RF receiving coil 14. In the fifth embodiment, similarly to the third to fourth embodiments, the recognized coil conductor can be displayed as the element icon 423 on the positioning MR image 401 to be movable. The image processing unit 335 can use the element icon 423 to perform the above-described recommended separation confirmation process and the rearrangement position determination process of the RF receiving coil 14.

  Although the fifth embodiment has been described above, among various modifications described in the other embodiments, the changes applicable in the fifth embodiment can be applied to the fifth embodiment.

  Further, the present invention is not limited to the first to fifth examples, and the present invention is not limited to the above-described embodiment, and various modifications can be employed.

FIG. 1 is a configuration diagram showing a configuration of an MRI system according to an embodiment of the present invention. FIG. 2 is a diagram illustrating an RF receiver coil used in one embodiment of the present invention. FIG. 3 is a diagram showing a coil conductor included in the RF receiving coil used in the embodiment of the present invention. FIG. 4 is a block diagram showing the configuration of the data processing unit according to the embodiment of the present invention. FIG. 5 is a conceptual diagram illustrating table movement according to an embodiment of the present invention. FIG. 6 is a diagram showing an example of a positioning MR image acquired in an embodiment of the present invention. FIG. 7 is a diagram showing an RF receiving coil used in an embodiment of the present invention. FIG. 8 is a diagram illustrating an example of a camera image acquired in an embodiment of the present invention. FIG. 9 is a diagram illustrating an example of a camera image obtained and processed in one embodiment of the present invention. . FIG. 10 is a diagram illustrating an example of a camera image obtained and processed in one embodiment of the present invention. FIG. 11 is a diagram illustrating an example of a positioning MR image acquired and processed in one embodiment of the present invention. FIG. 12 is a diagram illustrating an example of a positioning MR image acquired and processed in one embodiment of the present invention. FIG. 13 is a conceptual diagram showing the influence of the coil conductor of the RF receiving coil on the phase image acquired in one embodiment of the present invention. FIG. 14 is a diagram illustrating an example of a phase image acquired and processed in one embodiment of the present invention. FIG. 15 is a diagram showing a phase profile in one embodiment of the present invention. FIG. 16 is a diagram illustrating the influence of the coil conductor of the RF receiving coil on the phase image.

Explanation of symbols

1: MRI system, 2: MRI apparatus, 3: operation console, 11: static magnetic field space, 12: static magnetic field magnet unit, 13: gradient coil unit, 14: RF receiving coil, 142: RF transmitting / receiving coil, 15: table, 16: Cradle, 17: Positioning light, 18: Camera, 19: Optical sensor, 22: RF drive unit, 23: Gradient drive unit, 24: Data collection unit, 30: Control unit, 31: Storage unit, 32: Operation Unit 33: data processing unit 34: display unit 40: subject, 143: housing, 161: element mark, 331: image reconstruction unit, 332: phase profile generation unit, 333: phase correction unit, 334 : Position detection unit, 335: image processing unit, 336: phase image analysis unit, 401: positioning MR image, 403: region marker, 410: camera image, 413: frame 421: Coil indicator 423: Element icon

Claims (20)

A magnetic resonance imaging system for generating an image of a subject based on a magnetic resonance signal generated from the subject,
An RF coil that includes a coil conductor, is attached to a predetermined part of the subject, and receives a magnetic resonance signal;
An MR image generation unit that generates a positioning MR image showing an internal structure of the subject based on a magnetic resonance signal generated from the subject to which the RF coil is attached;
Indicating means for indicating a position of a specified region included in the positioning MR image or a position to move the RF coil;
A magnetic resonance imaging system comprising: A magnetic resonance imaging apparatus comprising a static magnetic field coil for generating a static magnetic field and a gradient magnetic field coil for generating a gradient magnetic field;
A table for placing the subject and moving the subject;
Control means for controlling the table so that the predetermined part of the subject is arranged at a position suitable for imaging the positioning MR image in the static magnetic field space;
Further comprising
The pointing means is a positioning light that indicates a position of the specified region or a position to move the RF coil;
The control means, after generating the positioning MR image, controls the table so that the positioning light indicates a position of the specified region or a position to move the RF coil.
The magnetic resonance imaging system of claim 1. The control means controls the table so that the positioning light indicates a position to move the RF coil after generating the positioning MR image,
The magnetic resonance imaging system according to claim 2, wherein the RF coil has a mark for associating the RF coil with a position indicated by the positioning light. A magnetic resonance imaging system for generating an image of a subject based on a magnetic resonance signal generated from the subject,
An RF coil that includes a coil conductor, is attached to a predetermined part of the subject, and receives a magnetic resonance signal;
An MR image generation unit that generates a positioning MR image showing an internal structure of the subject based on a magnetic resonance signal generated from the subject to which the RF coil is attached;
Position information acquisition means for acquiring position information of an area specified in the positioning MR image;
Distance specifying means for specifying a distance between the specified region and at least a part of the coil conductor;
A magnetic resonance imaging system comprising: 5. The magnetic resonance imaging system according to claim 4, wherein the position information of the specified region is position information of a region marker positioned corresponding to a predetermined anatomical feature included in the positioning MR image. A camera for imaging the RF coil attached to the subject;
A display device for displaying the positioning MR image;
Means for displaying the identified region as a region marker on the positioning MR image;
Further comprising
The magnetic resonance imaging system according to claim 4, wherein the display device displays a display indicating the region marker on a camera image of the RF coil photographed by the camera. A camera for imaging the RF coil attached to the subject;
Coil conductor detection means for detecting the position of at least a part of the coil conductor from a camera image taken by the camera;
A display device for displaying the positioning MR image;
The display device displays a display corresponding to at least a part of the detected coil conductor on the positioning MR image;
The magnetic resonance imaging system of claim 4. The RF coil has a housing, and the housing has an element mark having a predetermined color at a position corresponding to the position of the at least part of the coil conductor.
The magnetic resonance imaging system according to claim 7, wherein the coil conductor detection unit detects a position of at least a part of the coil conductor by identifying the predetermined color included in the camera image. The magnetic resonance imaging according to claim 7, wherein the coil conductor detection unit detects a position of at least a part of the coil conductor by matching with a prestored image model indicating the characteristics of the RF coil. ·system. A magnetic resonance imaging apparatus comprising a static magnetic field coil for generating a static magnetic field and a gradient magnetic field coil for generating a gradient magnetic field;
A table for placing the subject and moving the subject;
Further comprising
The said camera is mounted | worn with the said magnetic resonance imaging device in the position spaced apart from the main body of the said magnetic resonance imaging device so that the static magnetic field in the said magnetic resonance imaging device may not be affected. A magnetic resonance imaging system according to claim 1. A display device for displaying the positioning MR image;
The RF coil has a housing, and the housing has an element mark formed of a substance detectable by an MR image at a position corresponding to at least a part of the coil conductor.
The display device displays a positioning MR image including a display corresponding to the element mark;
The magnetic resonance imaging system of claim 4. The magnetic resonance imaging system according to claim 1, wherein the positioning MR image is an image of a coronal section. The element mark is made of a material exhibiting a predetermined frequency characteristic,
The MR image generation unit includes a positioning MR image including the element mark formed of a material exhibiting the predetermined frequency characteristic, and a positioning MR image indicating an internal structure of the subject not including the element mark. 12. The magnetic resonance imaging system of claim 11, wherein the magnetic resonance imaging system is generated. The positioning MR image is a phase image;
The magnetic resonance imaging system further comprises image processing means for processing the phase image,
The pixel values of the pixels constituting the phase image correspond to the phase,
The image processing device identifies a position of at least a part of the coil conductor;
The magnetic resonance imaging system of claim 4. The image processing apparatus includes:
In the phase image, specify a region where the dispersion of pixel values is high,
Recognizing that the location showing the high dispersion is the position of at least part of the coil conductor;
The magnetic resonance imaging system of claim 14. The element mark is made of a material exhibiting a predetermined frequency characteristic,
The RF coil comprises a loop coil formed of the coil conductor;
The magnetic resonance imaging system of claim 11, wherein the loop coil is tuned to tune to at least two of the predetermined frequency and a frequency of 1H. The magnetic resonance imaging system according to claim 1, wherein the specified region is a diaphragm located between a lung and a liver of the subject. An RF coil that is attached to a predetermined part of a subject and receives a magnetic resonance signal generated from the subject,
A housing,
A coil conductor disposed in the housing;
With
The housing has an element mark at a position corresponding to the position of at least a part of the coil conductor,
When imaged by the magnetic resonance imaging apparatus, a positioning MR image including the element mark and a positioning MR image showing the internal structure of the subject not including the element mark can be reconstructed by selection. is there,
RF coil. A loop coil formed of the coil conductor;
The element mark is made of a material exhibiting a predetermined frequency characteristic,
The RF coil of claim 18, wherein the loop coil is tuned to tune to at least two of the predetermined frequency and a frequency of 1H. Comprising at least four rectangular loop coils formed of the coil conductor;
Forming at least two pairs of loop coils in which the at least two rectangular loop coils overlap each other in a direction perpendicular to the direction of the body axis of the subject;
The at least two loop coil pairs are arranged overlapping in the direction of the body axis;
The at least four rectangular loop coils overlap each other at at least one point;
The element mark is
19. The RF coil according to claim 17, wherein the RF coil is disposed at a point at an end of at least two loop coils located on both sides in a direction perpendicular to the direction of the body axis across the at least one point.