JP7326011B2 - Magnetic resonance imaging system - Google Patents

Description

Embodiments of the present invention relate to magnetic resonance imaging apparatus.

Conventionally, in a Magnetic Resonance Imaging (MRI) apparatus, a radio frequency coil (RF coil) for local use depending on an imaging target site may be attached to a subject. In addition, as one of the high-speed imaging methods, there is also a parallel imaging (PI) technology that shortens the imaging time by utilizing the sensitivity difference of multiple phased array coils (PAC) attached to the subject. Are known.

In these prior arts, before the start of imaging by the magnetic resonance imaging apparatus, an engineer or the like manually performs the task of attaching the high-frequency coil (coil setting).

JP 2012-245170 A

The problem to be solved by the present invention is to reduce the work time and work load required for coil setting.

A magnetic resonance imaging apparatus according to an embodiment includes a coil moving mechanism, a specifying section, and a control section. The coil moving mechanism moves a high-frequency coil that receives an MR (Magnet Resonance) signal from a subject so that it can be retracted from an imaging position. The specifying unit specifies a high-frequency coil to be used for examination of the subject according to imaging conditions. The control unit controls the coil moving mechanism to move the high-frequency coil specified by the specifying unit from the retracted position to the imaging position.

FIG. 1 is a block diagram showing an example of the configuration of a magnetic resonance imaging apparatus according to a first embodiment; FIG. FIG. 2 is a diagram illustrating an example of coil number information according to the first embodiment; FIG. 3 is a diagram illustrating an example of a combination of coil elements attached to a subject according to the first embodiment; FIG. 4 is a diagram illustrating an example of a flow of movement of coil elements by a coil arm according to the first embodiment; FIG. 5 is a diagram illustrating an example of a state in which coil elements are installed by the coil arm according to the first embodiment; FIG. 6 is a diagram illustrating an example of the elevating function of the coil element according to the first embodiment; FIG. 7 is a flowchart showing an example of the flow of coil setting and imaging processing according to the first embodiment. 8A and 8B are diagrams illustrating an example of a state in which an object is imaged according to the first embodiment; FIG. FIG. 9 is an example of a horizontal cross-sectional view of a pedestal according to the second embodiment. 10A and 10B are diagrams illustrating an example of a state in which the coil belt is stored in the frame according to the second embodiment. FIG. FIG. 11 is a diagram illustrating an example of a state in which the pedestal according to the second embodiment is viewed from the insertion opening direction of the top plate. FIG. 12 is a diagram illustrating an example of a method of moving the coil belt according to the second embodiment; FIG. 13 is a flowchart showing an example of the flow of coil setting and imaging processing according to the second embodiment. FIG. 14 is a diagram showing an example of movement of the coil belt according to the second embodiment in chronological order. 15A and 15B are diagrams illustrating an example of a method of moving the coil belt according to Modification 1. FIG. 16A and 16B are diagrams illustrating another example of a method of moving the coil belt according to Modification 1. FIG. FIG. 17 is an example of a cross-sectional view of a pedestal according to Modification 2. FIG.

Hereinafter, embodiments of the magnetic resonance imaging apparatus will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 is a block diagram showing an example of the configuration of a magnetic resonance imaging (MRI) apparatus according to this embodiment.

As shown in FIG. 1, the magnetic resonance imaging apparatus 100 includes a static magnetic field magnet 101, a gradient magnetic field coil 102, a gradient magnetic field power supply 103, a whole body radio frequency (Radio Frequency: RF) coil 104, a high frequency shield 105, A coil box 5, a coil arm 7, a plurality of coil elements 6a to 6n, a pedestal 9, a bed 106, a bed control circuit 107, a transmission circuit 108, a reception circuit 109, a sequence control circuit 110, and a computer. a system 120; Note that the magnetic resonance imaging apparatus 100 does not include the subject P (eg, human body).

The static magnetic field magnet 101 is a hollow cylindrical magnet that generates a uniform static magnetic field in the internal space.

In the present embodiment, the “cylindrical shape” or “cylindrical” is not limited to a shape in which the cross section perpendicular to the central axis of the cylinder is a perfect circle, and the cross section perpendicular to the central axis of the cylinder A shape in which the shape of is elliptical is also acceptable.

The gradient magnetic field coil 102 is a hollow cylindrical coil that generates a gradient magnetic field. More specifically, the gradient magnetic field coils 102 are individually supplied with electric current from a gradient magnetic field power supply 103, which will be described later, to generate gradients along the X-, Y-, and Z-axes that are orthogonal to each other in the space within the cylinder. Generate a magnetic field.

Here, the X-axis, Y-axis and Z-axis constitute an apparatus coordinate system unique to the magnetic resonance imaging apparatus 100 . For example, the Z-axis coincides with the cylindrical axis of the gradient coil 102 and is set along the magnetic flux of the static magnetic field generated by the static magnetic field magnet 101 . The X-axis is set along the horizontal direction perpendicular to the Z-axis, and the Y-axis is set along the vertical direction perpendicular to the Z-axis.

The gradient magnetic field power supply 103 supplies current to the gradient magnetic field coil 102 to generate gradient magnetic fields along the X, Y, and Z axes in the space inside the gradient magnetic field coil 102 .

The whole-body high-frequency coil 104 is arranged inside the gradient magnetic field coil 102, applies a high-frequency magnetic field to the imaging space in which the subject P is placed, and generates magnetic resonance from the subject P under the influence of the high-frequency magnetic field. A signal (hereinafter referred to as an MR (Magnet Resonance) signal) is received. Specifically, the whole-body high-frequency coil 104 is formed in a hollow, substantially cylindrical shape, and applies a high-frequency magnetic field to the space within the cylinder based on the RF pulse signal output from the transmission circuit 108 . The whole-body high-frequency coil 104 also receives MR signals generated from the subject P and outputs the received MR signals to the receiving circuit 109 . In FIG. 1, the whole-body high-frequency coil 104 is assumed to have both functions of transmission (application of high-frequency magnetic field) and reception of MR signals. May be adopted.

The high-frequency shield 105 is arranged, for example, between the gradient magnetic field coil 102 and the whole-body high-frequency coil 104 to shield the RF magnetic field generated by the whole-body high-frequency coil 104 . For example, the high-frequency shield 105 is formed in a substantially cylindrical shape, and is arranged in a space on the inner peripheral side of the gradient magnetic field coil 102 so as to cover the outer peripheral surface of the whole-body high-frequency coil 104 .

The transmission circuit 108 supplies the whole-body high-frequency coil 104 with an RF pulse corresponding to the Larmor frequency determined by the type of nucleus of interest and the strength of the magnetic field. The transmission circuit 108 includes, for example, an oscillation circuit, a phase selection circuit, a frequency conversion circuit, an amplitude modulation circuit, and a high frequency amplification circuit. An oscillating circuit generates radio frequency pulses at a resonance frequency specific to the nuclei of interest placed in the static magnetic field. The phase selection circuit selects the phase of the high frequency pulse output from the oscillation circuit. The frequency conversion circuit converts the frequency of the high frequency pulse output from the phase selection circuit. The amplitude modulation circuit modulates the amplitude of the high frequency pulse output from the frequency conversion circuit. The high frequency amplifier circuit amplifies the high frequency pulse output from the amplitude modulation circuit and supplies it to the whole body high frequency coil 104 . A high-frequency amplifier device including a high-frequency amplifier circuit may be provided outside the transmission circuit 108 .

The gantry 9 accommodates a static magnetic field magnet 101 , a gradient magnetic field coil 102 and a whole-body high-frequency coil 104 . Specifically, the gantry 9 has a cylindrical hollow bore B, and a static magnetic field magnet 101, a gradient magnetic field coil 102, a whole-body high-frequency coil 104, and a high-frequency shield 105 surround the bore B. are placed, and each is accommodated. Here, the space inside the bore B of the gantry 9 serves as an imaging space in which the subject P is arranged when the subject S is imaged.

The bed 106 has a table 106a on which the subject P is placed. insert inside. The bed 106 is installed, for example, so that its longitudinal direction is parallel to the central axis of the static magnetic field magnet 101 .

A spine coil 1106 for imaging the spine is installed on the top plate 106a. The spinal coil 1106 receives MR signals emitted from the subject P under the influence of the high-frequency magnetic field under the control of the receiving circuit 109 . Upon receiving the MR signal, the spine coil 1106 outputs the received MR signal to the receiving circuit 109 .

Under the control of the computer system 120, the bed control circuit 107 drives the drive mechanism of the bed 106a of the bed 106 to move the bed 106a in the longitudinal direction (Z-axis direction) and the vertical direction (Y-axis direction). It is the processor that executes the moving control.

Each of the plurality of coil elements 6a to 6n (hereinafter simply referred to as coil element 6 when the coil elements 6a to 6n are not particularly distinguished) is a surface coil capable of forming a phased array coil (PAC). be. In other words, a plurality of coil elements 6 are combined and installed on the subject P to function as a phased array coil. Further in other words, the phased array coil has multiple coil elements 6 . The coil element 6 is stored in the coil box 5 except when imaging. Also, the coil element 6 is taken out from the coil box 5 by the coil arm 7 and attached to the subject P. As shown in FIG. The coil element 6 attached to the subject P receives MR signals generated from the subject P and outputs the received MR signals to the receiving circuit 109 .

The coil element 6 is, for example, a one-loop coil, but may be a combination of a plurality of one-loop coils. The number of coil elements 6 stored in the coil box 5 is not particularly limited. Note that the coil element 6 may further have a transmission function of applying a high-frequency magnetic field. In this case, the coil element 6 attached to the subject P is connected to the transmission circuit 108 and applies a high frequency magnetic field to the subject S based on the RF pulse signal output from the transmission circuit 108 . The coil element 6 is an example of a high frequency coil in this embodiment. Also, a phased array coil in which a plurality of coil elements 6 are combined may be used as an example of the high frequency coil. Moreover, the coil element 6 is also called an assembly coil.

Note that the coil element 6 may further have a transmission function of applying an RF magnetic field. In that case, the coil element 6 is connected to a transmission circuit 108 which will be described later, and applies an RF magnetic field to the subject P based on an RF pulse signal output from the transmission circuit 108 .

A coil box 5 houses a plurality of coil elements 6 . The coil box 5 is positioned, for example, on the rear side (rear) of the pedestal 9 . In the present embodiment, the inlet side of the bore B is referred to as the front side (front side) of the pedestal 9 , and the side opposite to the inlet of the bore B is referred to as the rear side of the pedestal 9 . The coil box 5 is an example of a retracted position and a storage location (storage section) in this embodiment.

In addition, the coil box 5 of the present embodiment includes rails and a driving mechanism for feeding the coil element 6 to a position where the coil arm 7 can grip the coil element 6 . The details of the configuration of the coil box 5 will be described later.

Coil arm 7 moves one or more coil elements 6 . Specifically, the coil arm 7 extracts one or more coil elements 6 from the coil box 5 and attaches them to the subject P under the control of the computer system 120 . In addition, under the control of the computer system 120, the coil arm 7 moves one or more coil elements 6 so as to be retractable from the imaging position. Also, the coil arm 7 stores the one or more coil elements 6 in the coil box 5 when the one or more coil elements 6 are retracted from the imaging position. The coil arm 7 is an example of a coil moving mechanism in this embodiment. Further, the imaging position in the present embodiment is a position covering the FOV (field of view).

The receiving circuit 109 analog-to-digital (AD) converts analog MR signals output from the whole-body high-frequency coil 104, the coil element 6 attached to the subject P, or the spinal coil 1106 to generate MR data. . The receiving circuit 109 also transmits the generated MR data to the sequence control circuit 110 . Note that AD conversion may be performed in the whole-body high-frequency coil 104 , the coil element 6 , or the spinal coil 1106 . Further, the receiving circuit 109 can perform arbitrary signal processing other than AD conversion.

The sequence control circuit 110 images the subject P by controlling the gradient magnetic field power supply 103 , the transmission circuit 108 and the reception circuit 109 based on the sequence information transmitted from the computer system 120 . The sequence control circuit 110 may be implemented by a processor, or by a mixture of software and hardware.

Sequence information is information defining a pulse sequence executed in an examination by the magnetic resonance imaging apparatus 100 . The sequence information includes the intensity of the current supplied by the gradient magnetic field power supply 103 to the gradient magnetic field coil 102 and the timing of supplying the current, the intensity of the RF pulse transmitted by the transmission circuit 108 to the whole-body high-frequency coil 104, and the timing of applying the RF pulse. , the timing at which the receiving circuit 109 detects the MR signal, and the like are defined.

In addition, the sequence information includes the imaging conditions specified by the operator, such as the imaging site, the insertion direction of the subject P, the height of the subject P, the parallel imaging (PI) acceleration factor, It is assumed to be generated by the computer system 120 based on information on many imaging parameters such as FOV, TR (repetition time), TE (echo time), number of slices, slice thickness, and the like.

The insertion direction of the subject P is either "head first" in which the head side of the subject P is inserted first into the bore B or "foot first" in which the foot side of the subject P is first inserted into the bore B. is.

The parallel imaging acceleration factor is also called a magnification rate or a thinning rate. Generally, in parallel imaging, the imaging time is shortened by thinning and acquiring k-space data in the phase encoding direction. In other words, in parallel imaging, it is possible to increase the speed according to the thinning rate of k-space data. For example, if the thinning rate (acceleration factor) is 4, the imaging time is shortened to about 1/4.

The computer system 120 performs overall control of the magnetic resonance imaging apparatus 100, data acquisition, image reconstruction, and the like. More specifically, computer system 120 controls sequence control circuit 110 , bed control circuit 107 and coil arm 7 . The computer system 120 has an interface circuit 121 , a memory circuit 122 , a processing circuit 123 , an input interface 124 and a display 125 . The computer system 120 is an example of a control system for the magnetic resonance imaging apparatus 100 in this embodiment.

The interface circuit 121 transmits sequence information to the sequence control circuit 110 and receives MR data from the sequence control circuit 110 . Further, upon receiving the MR data, the interface circuit 121 stores the received MR data in the storage circuit 122 .

The storage circuit 122 stores various programs. The storage circuit 122 stores MR data received by the interface circuit 121, time-series data arranged in k-space by an imaging function 123b described later, magnetic resonance images (MR images) generated by an image generating function 123e described later, and the like. memorize The storage circuit 122 also stores various programs. The storage circuit 122 is implemented by, for example, a RAM (Random Access Memory), a semiconductor memory device such as a flash memory, a hard disk, an optical disk, or the like. Note that the storage circuit 122 is also used as a non-transitory hardware storage medium.

The input interface 124 receives various instructions and information inputs from an operator such as a doctor or a radiological technologist. The input interface 124 is implemented by, for example, a trackball, switch buttons, mouse, keyboard, and the like. The input interface 124 is connected to the processing circuit 123 , converts an input operation received from the operator into an electric signal, and outputs the electric signal to the processing circuit 123 .

The display 125 displays various GUIs (Graphical User Interfaces), magnetic resonance images, etc. under the control of the processing circuit 123 .

The processing circuit 123 performs overall control of the magnetic resonance imaging apparatus 100 . More specifically, the processing circuit 123 has a reception function 123a, an imaging function 123b, a specific function 123c, a movement control function 123d, an image generation function 123e, and a display control function 123f.
The reception function 123a is an example of a reception unit. The imaging function 123b is an example of an imaging unit. The specific function 123c is an example of a specific part. The movement control function 123d is an example of a control unit. The image generation function 123e is an example of an image generation unit. The display control function 123f is an example of a display control unit.

Here, for example, the reception function 123a, the imaging function 123b, the specific function 123c, the movement control function 123d, the image generation function 123e, and the display control function 123f, which are components of the processing circuit 123, can be executed by a computer. It is stored in the memory circuit 122 in the form of a program. The processing circuit 123 reads each program from the storage circuit 122 and executes each read program, thereby realizing a function corresponding to each program. In other words, the processing circuit 123 with each program read has each function shown in the processing circuit 123 of FIG. Note that in FIG. 1, the single processing circuit 123 implements each of the reception function 123a, the imaging function 123b, the specific function 123c, the movement control function 123d, the image generation function 123e, and the display control function 123f. However, the processing circuit 123 may be configured by combining a plurality of independent processors, and each processor may implement each processing function by executing each program.

The term "processor" used in the above description is, for example, a CPU (central preprocessing unit), a GPU (Graphics Processing Unit), or an application specific integrated circuit (ASIC), a programmable logic device (e.g., Circuits such as Simple Programmable Logic Device (SPLD), Complex Programmable Logic Device (CPLD), and Field Programmable Gate Array (FPGA)). Note that instead of storing the program in the memory circuit 122, the program may be configured to be directly installed in the circuit of the processor. In this case, the processor realizes its function by reading and executing the program embedded in the circuit.

The reception function 123a receives an operator's operation via the input interface 124 . For example, the reception function 123a receives (acquires) imaging parameters such as imaging conditions specified by the operator, such as the imaging site, the insertion direction of the subject P, the height of the subject P, the parallel imaging acceleration factor, and the FOV. do). The reception function 123a also receives an operation for starting or ending imaging input to the input interface 124 by the operator. The reception function 123a sends the received imaging conditions to the imaging function 123b and the specific function 123c. When receiving an operation to start or end imaging, the reception function 123a notifies the imaging function 123b and the movement control function 123d of the start or end of imaging.

The imaging function 123b generates sequence information based on the imaging conditions received by the receiving function 123a, and controls imaging by transmitting the generated sequence information to the sequence control circuit 110. FIG. In addition, the imaging function 123b arranges the MR data sent from the sequence control circuit 110 as a result of imaging two-dimensionally or three-dimensionally according to the amount of phase encoding and the amount of frequency encoding imparted by the above-described gradient magnetic field. Save to The aligned MR data is called k-space data.

In addition, in the present embodiment, the imaging function 123b performs imaging for collecting a sensitivity map (sensitivity distribution information) before main imaging in order to perform high-speed imaging processing by parallel imaging. For example, the imaging function 123b performs separate scans for each of the whole-body high-frequency coil 104 and the coil elements 6 placed on the subject P. FIG. The imaging function 123b provides MR data (or image data) obtained as imaging results of the whole-body high-frequency coil 104 and MR data (or image data) obtained as imaging results of each of the coil elements 6 placed on the subject P ( or image data), a sensitivity map of each coil element 6 is generated.

Further, in this embodiment, the imaging function 123b performs imaging of a locator image (Locator) before imaging of a magnetic resonance image for diagnosis (main imaging) and imaging of a sensitivity map. A locator image, also called a scout image (Scout), is an image used to locate the FOV. For example, in the present embodiment, the imaging function 123b executes a process of imaging a three-axis locator image including an axial cross-sectional image (Axial), a sagittal cross-sectional image (Sagittal), and a coronal cross-sectional image (Coronal). .

Further, the imaging function 123b determines the initial value of the FOV based on the imaging site, the insertion direction of the subject P, the height of the subject P, etc., when the FOV is not specified by the operator. If the operator changes the initial value of the FOV after displaying the locator image, the imaging function 123b changes the sequence information based on the changed FOV.

In addition, the imaging function 123b transmits the position of the tabletop 106a based on the imaging conditions to the bed control circuit 107 before starting imaging. Note that the imaging function 123b may notify the bed control circuit 107 of, for example, the imaging region or FOV of the subject P instead of directly designating the position of the tabletop 106a.

The specifying function 123c specifies one or more coil elements 6 to be used for examination of the subject P based on imaging conditions. Assume that the imaging condition used to specify the coil element 6 is at least one of an imaging region, an imaging field of view, and an acceleration factor. More specifically, the specifying function 123c determines the subject P specify the coil element 6 to be used for the inspection.

FIG. 2 is a diagram showing an example of the number-of-coils information 1221 according to this embodiment. As shown in FIG. 2, the coil number information 1221 associates an acceleration factor, a lower limit value ( _zT ) of the number of coils in the Z-axis direction, and a lower limit value ( _xT ) of the number of coils in the X-axis direction. ing. Note that in the imaging conditions, different values may be set for the acceleration factor in the Z-axis direction and the acceleration factor in the X-axis direction.

The lower limit value (z _T ) of the number of coils in the Z-axis direction is the number of coil elements 6 installed in the Z-axis direction at which the g-factor becomes a predetermined value or less in imaging with each acceleration factor. Also, the lower limit value (x _T ) of the number of coils in the X-axis direction is the number of coil elements 6 installed in the X-axis direction at which the g-factor becomes a predetermined value or less in imaging with each acceleration factor. The g-factor is a factor that reduces SNR (Signal to Noise Ratio) in parallel imaging.

The lower limit value (z _T ) of the number of coils in the Z-axis direction and the lower limit value (x _T ) of the number of coils in the X-axis direction are examples of the lower limit value of the number of coil elements 6 in this embodiment. The coil number information 1221 is stored in the memory circuit 122, for example.

Moreover, FIG. 3 is a diagram showing an example of a combination of the coil elements 6 attached to the subject P according to this embodiment. In the example shown in FIG. 3, for example, the lower limit value ( _zT ) of the number of coils in the Z-axis direction is "3", and the lower limit value ( _xT ) of the number of coils in the X-axis direction is "1". In the example shown in FIG. 3, the length of the FOV 900 in the Z-axis direction is _zs , and the length in the X-axis direction is _xs .

In this embodiment, the dimensions of the FOV 900 are defined by the lengths in the X-, Y-, and Z-axis directions. Length and X-axis length are used.

The specifying function 123c specifies the combination with the smallest number of coil elements 6 among the combinations of the coil elements 6 that satisfy the conditions of formulas (1) to (4).

_Nx is the number of coil elements 6 installed on the subject P in the X-axis direction. _Nz is the number of coil elements 6 installed on the subject P in the Z-axis direction. Also, _xe is the lateral width (length in the X-axis direction) of each coil element 6 . _ze is the vertical length (length in the Z-axis direction) of each coil element 6 .

Equation (1) indicates a condition that the length of the combined coil elements 6 in the X-axis direction is equal to or greater than the length (x _s ) of the FOV 900 in the X-axis direction. Expression (2) also indicates a condition that the length of the combined coil elements 6 in the Z-axis direction is greater than or equal to the length (z _s ) of the FOV 900 in the Z-axis direction. Expression (3) also indicates a condition that the number (N _x ) of coil elements 6 in the X-axis direction is equal to or greater than the lower limit value (x _T ) of the number of coils in the X-axis direction. Expression (4) also indicates a condition that the number of coil elements 6 in the Z-axis direction (N _z ) is equal to or greater than the lower limit value (z _T ) of the number of coils in the Z-axis direction.

In other words, the specific function 123c determines that the number of coil elements 6 is the minimum number among the combinations of coil elements 6 that are equal to or greater than the lower limit of the number of coil elements 6 defined by the number-of-coils information 1221 and that can cover the FOV 900. Identify the combination that is

In the example shown in FIG. 3, the minimum value of the number (N _x ) of the coil elements 6 in the X-axis direction that satisfies the conditions of Equations (1) to (4) is "2", and the number of coil elements 6 in the Z-axis direction is "2". The minimum value of (N _z ) is "5". In this case, the specifying function 123c specifies a combination of ten coil elements 6a to 6j as a combination of coil elements 6 to be used for examination of the subject P. FIG. Also, in this case, the coil elements 6a to 6j function as a phased array coil 60. FIG.

The number of coil elements 6 in the X-axis direction (N _x ) is also referred to as the number of rows of coil elements 6 . The number (N _z ) of coil elements 6 in the Z-axis direction is also called the number of rows of coil elements 6 . The number of coil elements 6 installed on the subject P, that is, the number of coil elements 6 forming the phased array coil 60 is not limited to this.

In the examples shown in FIGS. 2 and 3, both the lower limit of the number of coils in the Z-axis direction and the lower limit of the number of coils in the X-axis direction are specified, but only one of them may be specified. Also, the lower limit of the number of coils in the Z-axis direction and the lower limit of the number of coils in the X-axis direction may be different values depending on the slice direction. Note that the method for specifying the lower limit of the number of coil elements 6 to be installed is not limited to the method described above. For example, the specific function 123c may calculate the lower limit of the number of coils in the Z-axis direction and the lower limit of the number of coils in the X-axis direction based on the acceleration factor.

Further, the specifying function 123c does not specify the combination of the coil elements 6 used for examination of the subject P, but simply specifies the number of columns and the number of rows of the coil elements 6, and sends the specified result to the movement control function 123d. It is good as a thing.

The specifying function 123c notifies the specified combination of coil elements 6 (coil elements 6a to 6j in the case of FIG. 3) to the movement control function 123d. Further, when the identification function 123c identifies one coil element 6 instead of a combination of a plurality of coil elements 6 as an installation target on the subject P, the movement control function 123d confirms that one coil element 6 has been identified. to notify.

Further, the specifying function 123c notifies the installation target position of the specified combination of the coil elements 6 to the movement control function 123d. The installation target position of the specified combination of the coil elements 6 is the range covering the FOV 900, as shown in FIG.

Returning to FIG. 1, the movement control function 123d controls the coil arm 7 to move the identified one or more coil elements 6 from the coil box 5 to a position (imaging position) covering the FOV 900 of the subject P. . The movement control function 123d, for example, executes control to move the coil arm 7 in the Z-axis direction and the upper Y-axis direction. Further, the movement control function 123d may perform control to move the coil arm 7 in the left-right direction (X-axis direction).

Further, the movement control function 123d controls the coil element movement mechanism in the coil box 5 to send the specified coil element 6 to a position where the coil arm 7 can grip it.

Here, movement of the coil element 6 will be described with reference to FIGS. 4 to 6. FIG. FIG. 4 is a diagram showing an example of a top view of the coil arm 7 according to this embodiment. In FIG. 4, the pedestal 9 and the coil box 5 are shown horizontally traversed so that the internal configuration can be seen. 4, the FOV 900 and the installation target position 901 of the coil element 6 are positioned on the chest of the subject P as an example.

As shown in FIG. 4 , the coil arm 7 has a board 72 and a board moving mechanism 71 . The coil box 5 also has rails 51a to 51d (hereinafter simply referred to as rails 51 unless otherwise specified).

The board 72 is a member capable of holding the coil element 6 . The board moving mechanism 71 includes, for example, a motor and an encoder, and moves the board 72 in the Z-axis direction and the upper Y-axis direction under the control of the movement control function 123d. Also, the board moving mechanism 71 may be capable of moving the board 72 in the X-axis direction.

Each of the coil elements 6 stored in the coil box 5 is installed movably on the rails 51 . For example, it is assumed that a coil element moving mechanism capable of moving on the rail 51 is provided below the coil element 6 . In addition, the coil element moving mechanism moves the coil element 6 to be placed on the subject P under the holding part 720 under the control of the movement control function 123d. The coil element moving mechanism includes, for example, a motor, an encoder, and a pinion, and moves on the rail 51 by driving the motor. Note that the method of moving the coil element 6 is not limited to this.

Next, the placement of the coil element 6 moved to the lower side of the coil element 6 on the subject P will be described.

FIG. 5 is a diagram showing an example of the flow of movement of the coil element 6 by the coil arm 7 according to this embodiment. The left side of FIG. 5 is a top view of the coil arm 7, and the coil box 5 and the mount 9 are shown in a horizontally crossed state as in FIG. The right side of FIG. 5 is an enlarged side view of the coil arm 7 and coil element 6 portions.

As shown in the upper left diagram of FIG. 5 , the coil element 6 to be installed on the subject P is moved under the holding section 720 by the coil element moving mechanism and the rail 51 . In the example shown in FIG. 5, the coil elements 6e, 6d, 6i, and 6j are assumed to be the coil elements 6 specified to be installed on the subject P. In the example shown in FIG.

As shown in the upper right diagram of FIG. 5, the coil element 6 includes projections 61a and 61b (hereinafter simply referred to as projections 61 unless otherwise distinguished). In addition, the coil element 6 includes spherical first joint portions 62a and 62b (hereinafter simply referred to as first joint portions 62 unless otherwise distinguished) and second joint portions 63a and 63b having a C-shaped cross section. (hereinafter simply referred to as the second joint portion 63 when not particularly distinguished). A first joint portion 62 and a second joint portion 63 of adjacent coil elements 6 in the coil box 5 are fitted. Further, by moving the coil element 6 by the coil element moving mechanism and the rail 51, the first joint portion 62 or the second joint portion 63 of the coil element 6 to be moved and the second joint portion 63 of the coil element 6 not to be moved. One joint 62 or the second joint 63 is separated.

5, the board 72 of the coil arm 7 includes holding portions 720a and 720b (hereinafter simply referred to as holding portion 720 unless otherwise specified). The number of holding portions 720 provided on the board 72 is the same as the number of coil elements 6 stored in the coil box 5, for example.

The holding portion 720 includes recesses 721a and 721b (hereinafter simply referred to as recesses 721 unless otherwise specified). The concave portion 721 has a shape that can be fitted with the convex portion 61 of the coil element 6 .

For example, as shown in the middle diagram on the right side of FIG. This state is a state in which the coil element 6 is held by the board 72 .

The board moving mechanism 71 lifts the coil element 6 by moving the board 72 upward while the coil element 6 is held by the board 72 .

5, the board moving mechanism 71 moves the coil element 6 above the installation target position 901 of the subject P placed on the top plate 106a. Moving. In the example shown in the lower left diagram of FIG. 5, the board moving mechanism 71 moves the coil element 6 by extending the small arm 71a holding the board 72 toward the base 9. is not limited to this. The small arm 71 a may be included in the board moving mechanism 71 or folded under the board moving mechanism 71 .

5, the board moving mechanism 71 moves the coil element 6 above the installation target position 901, and then cables 601a and 601j (hereinafter referred to as cables 601a and 601j) connected to the holding portion 720. When not distinguished, simply referred to as a cable 601) is extended to lower the coil element 6.

FIG. 6 is a diagram showing an example of the elevating function of the coil element 6 according to this embodiment. As shown in FIG. 6, the board moving mechanism 71 further includes a tension sensor 701, a reel 702, and cylindrical support members 703a to 703c (hereinafter simply referred to as support member 703 unless otherwise specified). The cable 601 is wound around a reel 702 and is let out from the bottom of the board 72 as the reel 702 rotates. In addition, the cable 601 returns to the state of being wound around the reel 702 by rotating the reel 702 in the reverse direction by the amount of rotation equal to the amount of rotation when the reel 702 was paid out.

A tension sensor 701 measures the tension of the cable 601 . When the coil element 6 descends to the position where it contacts the subject P, the tension of the cable 601 is reduced. For example, tension sensor 701 transmits the measured tension to processing circuitry 123 . The movement control function 123d controls the reel 702 to stop the extension of the cable 601 when the transmitted tension falls below a predetermined threshold. Also, when the imaging is completed, the movement control function 123d controls the reel 702 to wind the cable 601. FIG. In addition, the movement control function 123 d controls the coil arm 7 after the winding of the cable 601 is completed to move the coil element 6 so as to be retractable from the imaging position and store it in the coil box 5 .

Note that the tension sensor 701 and reel 702 may be included in the coil box 5 .

Also, although not shown in FIG. 6, the cable 601 is assumed to be connected to the receiving circuit 109 . Coil element 6 transmits the received MR signal to receiving circuit 109 via cable 601 . Note that the coil element 6 and the receiving circuit 109 may communicate wirelessly without using the cable 601 .

Here, returning to FIG. 1, the image generation function 123e generates a magnetic resonance image based on MR data. Specifically, the image generation function 123e performs reconstruction processing such as Fourier transform and correction based on a sensitivity map on the k-space data stored in the storage circuit 122 to form a two-dimensional or three-dimensional magnetic resonance image. to generate

The image generation function 123e stores the generated magnetic resonance image in the storage circuit 122, for example. Further, the image generation function 123e may notify the display control function 123f of completion of generation of the magnetic resonance image.

The display control function 123f causes the display 125 to display the magnetic resonance image generated by the image generation function 123e. For example, the display control function 123f displays a locator image. The display screen of the locator image is, for example, a screen on which the operator can input an operation to change the range of the FOV 900 . The display control function 123f also displays a magnetic resonance image for diagnosis as a result of the main imaging.

Next, the flow of coil setting and imaging processing performed by the magnetic resonance imaging apparatus 100 configured as described above will be described.

FIG. 7 is a flowchart showing an example of the flow of coil setting and imaging processing according to this embodiment. The processing of this flowchart is started, for example, when the reception function 123a receives an operation for starting imaging by the operator via the input interface 124 .

The reception function 123a acquires imaging conditions specified by the operator via the input interface 124 . Here, the reception function 123a acquires, for example, the imaging region, the insertion direction of the subject P, the height of the subject P, and the acceleration factor of parallel imaging as imaging conditions.

Next, the imaging function 123b calculates the initial value of the FOV based on the imaging region designated by the operator (S2).

Next, the imaging function 123b transmits the position of the tabletop 106a based on the imaging region designated by the operator to the bed control circuit 107 via the interface circuit 121. FIG. For example, the imaging function 123b determines the position of the tabletop 106a so that the center of the imaging region in the Z-axis direction is positioned at the center of the magnetic field of the gantry 9. FIG. The bed control circuit 107 moves the top board 106a into the gantry 9 based on the instruction from the imaging function 123b (S3).

FIG. 8 is a diagram showing an example of the state of imaging the subject P according to the present embodiment. For example, when the imaging region is the chest, the bed control circuit 107 moves the table 106a so that the center of the chest of the subject P in the Z-axis direction is positioned at the magnetic field center C, as shown in FIG. .

Next, the imaging function 123b performs imaging for obtaining a locator image (S4). The imaging function 123b converts MR data sent from the sequence control circuit 110 as a result of imaging to generate k-space data. The imaging function 123b stores the k-space data in the storage circuit 122. FIG.

Next, the image generation function 123e generates a locator image by performing reconstruction processing on the k-space data stored in the storage circuit 122 (S5).

Next, the display control function 123f causes the display 125 to display the locator image generated by the image generation function 123e (S6). Here, the operator refers to the locator image and inputs the FOV 900 for main imaging.

Then, the reception function 123a receives the FOV 900 for main imaging input by the operator via the input interface 124 (S7). The receiving function 123a sends the input FOV900 to the imaging function 123b.

Next, the imaging function 123b determines whether or not the distance between the center of the input FOV 900 in the Z-axis direction and the magnetic field center C is equal to or greater than a predetermined distance (S8). The predetermined distance is, for example, a distance that can ensure the accuracy of imaging of the FOV 900, and is determined in advance. Note that the value of the predetermined distance is not particularly limited.

When the imaging function 123b determines that the distance between the center of the input FOV 900 in the Z-axis direction and the magnetic field center C is greater than or equal to the predetermined distance (S8 "Yes"), the imaging function 123b moves the input FOV 900 in the Z-axis direction. The bed control circuit 107 moves the top plate 106a so that the center of the magnetic field is positioned at the magnetic field center C (S9).

When the imaging function 123b determines that the distance between the input center of the FOV 900 in the Z-axis direction and the magnetic field center C is less than a predetermined distance (S8 "No"), the imaging function 123b moves the tabletop 106a. Instead, the process proceeds to S10.

Further, the specifying function 123c selects the elements used for the main imaging from among the elements (coil elements, sections) included in the spinal coil 1106 based on the input FOV 900 (S10). In FIG. 8, an element 1106a corresponding to the length of the FOV 900 in the Z-axis direction is selected from the spinal coil 1106 as an example. The specific function 123 c sends the selection result to the sequence control circuit 110 via the interface circuit 121 .

Next, the specifying function 123c performs a combination of coil elements 6 attached to the subject P and a combination of the coil elements 6 based on the acceleration factor specified by the operator, the number of coils information 1221, and the dimensions of the FOV 900. is specified (S11). The identification function 123c sends the identification result to the movement control function 123d.

The movement control function 123d controls the coil arm 7, extracts the coil elements 6 included in the combination specified by the specifying function 123c from the coil box 5, and attaches them to the installation target position 901 of the subject P (S12). For example, the movement control function 123d controls the coil arm 7 to move the coil element 6 above the installation target position 901, then extends the cable 601 to lower the coil element 6, and as shown in FIG. The coil element 6 is brought into close contact with the installation target position 901 of the subject P.

Next, the imaging function 123b performs imaging of the sensitivity map (S13).

Then, the imaging function 123b executes imaging of a magnetic resonance image for diagnosis (main imaging) (S14).

The image generation function 123e performs reconstruction processing such as Fourier transform and correction based on the sensitivity map to generate a diagnostic magnetic resonance image (S15).

The display control function 123f causes the display 125 to display the diagnostic magnetic resonance image generated by the image generation function 123e (S16).

Then, the reception function 123a determines whether or not the operator's operation to change the acceleration factor or the FOV 900 has been received (S17).

When the receiving function 123a determines that an operation to change the acceleration factor or the FOV 900 by the operator has been received (S17 "Yes"), the receiving function 123a sends the contents of the change to the imaging function 123b and the specific function 123c. In this case, the process returns to S8.

When the reception function 123a determines that the operator's operation to change the acceleration factor or the FOV 900 has not been received (S17 "No"), the reception function 123a determines whether or not the operator's operation to end imaging has been received (S18). .

When the reception function 123a determines that the operator's operation to end imaging has not been received (S18 "No"), the process returns to S14 and the main imaging process is continued.

Further, when the reception function 123a determines that it has received an operation to end imaging by the operator (“Yes” in S18), the reception function 123a notifies the movement control function 123d and the imaging function 123b of the end of imaging. In this case, the movement control function 123d controls the coil arm 7 to house the coil element 6 placed on the subject P in the coil box 5 (S19).

In addition, the imaging function 123b notifies the bed control circuit 107 of the end of imaging. The bed control circuit 107 moves the position of the tabletop 106a to the position before the start of imaging, and takes the subject P out of the gantry 9 (S20). Here, the processing of this flowchart ends.

As described above, the magnetic resonance imaging apparatus 100 of the present embodiment includes the coil arm 7 for moving the coil element 6 so as to be retractable from the imaging position. The element 6 is identified, and the coil arm 7 is controlled to move the identified coil element 6 from the retracted position to the imaging position. That is, according to the magnetic resonance imaging apparatus 100 of the present embodiment, the coil setting of the coil element 6 used for examination of the subject P is automatically performed without relying on the operator's manual work. , and the workload can be reduced. Further, according to the magnetic resonance imaging apparatus 100 of the embodiment, since the coil element 6 is automatically moved so as to be retractable from the imaging position, the work time and workload for removing the coil after imaging can be reduced. be able to.

For example, when an engineer manually sets the coil, an inexperienced engineer may install the high-frequency coil in the wrong installation position. In such a case, the installation work may need to be redone, increasing work time and workload. In addition, even for a skilled engineer, setting the coils requires a lot of time and a heavy workload. On the other hand, in the magnetic resonance imaging apparatus 100 of the present embodiment, by automatically moving the coil element 6 that matches the imaging conditions to the imaging position, a uniform coil can be obtained regardless of the technician's experience and technique. Since setting can be completed in a short time, it is possible to reduce the work time and work load required for coil setting.

Further, conventionally, after a phased array coil in which a plurality of coil elements are housed in one housing is placed on the subject, an engineer or the like selects a coil element that enables the electrical reception of MR signals. was In this case, even if the coil is set in the correct position, the coil element that enables MR signals to be received is manually selected from among the plurality of coil elements contained in one housing. A choice could occur. On the other hand, in the magnetic resonance imaging apparatus 100 of the present embodiment, the coil element 6 used for examination of the subject P is automatically identified and moved to the imaging position, so manual erroneous selection is avoided. can do.

In addition, since the imaging condition of the present embodiment is at least one of the imaging region, FOV900, or parallel imaging acceleration factor, according to the magnetic resonance imaging apparatus 100 of the present embodiment, the imaging region, the imaging field of view, or An adapted coil element 6 suitable for parallel imaging acceleration factors can be set automatically.

Further, since the imaging position of the present embodiment is a position covering the FOV 900, according to the magnetic resonance imaging apparatus 100 of the present embodiment, the coil element 6 suitable for the imaging conditions is It can be attached so as to cover the FOV 900 of the subject P automatically.

Moreover, the coil arm 7 of this embodiment stores the coil element 6 in the coil box 5 when retracting the coil element 6 from the imaging position. Therefore, according to the magnetic resonance imaging apparatus 100 of the present embodiment, since the coil element 6 is automatically housed, it is possible to further reduce the work time and work load of the technician.

In addition, the coil element 6 of the present embodiment is a plurality of coil elements that function as the phased array coil 60, and the magnetic resonance imaging apparatus 100 of the present embodiment has the lower limit value of the number of coil elements defined in the coil number information 1221. , and the dimensions of the FOV 900, the coil elements 6 to be used for examination of the subject P are specified. Specifically, the magnetic resonance imaging apparatus 100 of the present embodiment has a combination of coil elements 6 that is equal to or greater than the lower limit of the number of coil elements 6 defined in the number of coils information 1221 and that can cover the FOV 900. Among them, the combination that minimizes the number of coil elements 6 is specified. For this reason, according to the magnetic resonance imaging apparatus 100 of the present embodiment, the number of coil elements 6 sufficient to image the FOV 900 is ensured, and redundant coil elements 6 included in the phased array coil 60 are reduced. For example, if the phased array coil includes extra coil elements, interference between the coil elements may degrade the image quality of the magnetic resonance image. On the other hand, according to the magnetic resonance imaging apparatus 100 of the present embodiment, it is possible to reduce the generation of noise due to the interference between the coil elements 6 and to pick up a high-quality magnetic resonance image.

The lower limit of the number of coil elements defined in the number of coils information 1221 is the installed number of coil elements 6 at which the g-factor becomes a predetermined value or less in imaging with each acceleration factor. According to the magnetic resonance imaging apparatus 100 of the present embodiment, since parallel imaging is performed in a state where the g-factor is equal to or less than a predetermined value, a decrease in SNR is reduced, and deterioration in image quality of magnetic resonance images in high-speed imaging is suppressed. can do.

Also, in the magnetic resonance imaging apparatus 100 of the present embodiment, the coil box 5 is positioned behind the pedestal 9 . Since the rear of the magnetic resonance imaging apparatus 100 is outside the movement range of the subject P, the technician, etc., and the tabletop 106a, by installing the coil box 5 at this position, the coil box 5 can move toward the subject P, the technician, etc. , and the operation of the top plate 106a can be avoided.

In this embodiment, the spine coil 1106 is installed on the top plate 106a, but a configuration in which the spine coil 1106 is not installed may be adopted.

In this embodiment, the processing circuit 123 has the movement control function 123d, but a coil arm control circuit for controlling the coil arm 7 may be provided separately from the processing circuit 123. When adopting this configuration, the coil arm control circuit is an example of the control unit.

Further, in the present embodiment, the specifying function 123c notifies the specified combination of the coil elements 6 to the movement control function 123d. The number of columns and the number of rows may be notified to the movement control function 123d.

Also, in the present embodiment, the coil element 6 retracted from the imaging position is stored in the coil box 5, but a configuration without the coil box 5 may be employed. In this case, the coil element 6 retracted from the imaging position may be positioned at the rear of the pedestal 9 .

(Second embodiment)
In the above-described first embodiment, the coil box 5 located behind the pedestal 9 of the magnetic resonance imaging apparatus 100 is the retracted position and storage location (storage unit) of the high-frequency coil. In contrast, in the second embodiment, the high-frequency coil retraction position and storage location are provided inside the gantry 9 .

A magnetic resonance imaging apparatus 100 of this embodiment includes a static magnetic field magnet 101, a gradient magnetic field coil 102, a gradient magnetic field power supply 103, a whole-body high-frequency coil 104, a high-frequency shield 105, a pedestal 9, a bed 106, and a bed. It comprises a control circuit 107 , a transmission circuit 108 , a reception circuit 109 , a sequence control circuit 110 and a computer system 120 . A computer system 120 of this embodiment has an interface circuit 121, a storage circuit 122, a processing circuit 123, an input interface 124, and a display 125, as in the first embodiment. As in the first embodiment, the processing circuit 123 of this embodiment includes a reception function 123a, an imaging function 123b, a specific function 123c, a movement control function 123d, an image generation function 123e, and a display control function. 123f. Further, the mount 9 of the present embodiment stores a plurality of coil belts inside.

A location for storing the coil belt and a technique for moving the high-frequency coil according to the present embodiment will be described with reference to FIGS. 9 to 12. FIG.

FIG. 9 is an example of a horizontal cross-sectional view of the mount 9 according to this embodiment. As shown in FIG. 9, the pedestal 9 is provided with two coil outlets 91a and 91b (hereinafter referred to simply as the coil outlet 91 unless otherwise specified) along the longitudinal direction of the top plate 160a.

FIG. 10 is a diagram showing an example of a storage state of coil belts (belt-shaped coils) 1060a to 1060h (hereinafter simply referred to as coil belts 1060 unless otherwise specified) in the gantry 9 according to this embodiment. The coil belt 1060 in this embodiment has flexibility. Also, the coil belt 1060 is assumed to include a plurality of coil elements 6 . A plurality of coil elements 6 included in the coil belt 1060 placed on the subject P functions as a phased array coil. Note that the number of coil belts 1060 is not limited to the example shown in FIG. In this embodiment, the coil element 6 included in the coil belt 1060 may be an example of a high frequency coil, and the coil belt 1060 may be an example of a high frequency coil.

As shown in FIG. 10 , the retracted position and storage location of the coil belt 1060 are provided inside the frame 9 . More specifically, the retracted position and storage location of the coil belt 1060 in this embodiment is the lower part of the gantry 9 (position lower than the top plate 106a).

Moreover, FIG. 11 is a diagram showing an example of a state in which the mount 9 according to the present embodiment is viewed from the insertion opening direction of the top plate 106a. As shown in FIG. 11, the tip of the coil belt 1060 is connected to the lead-out portion 1007 .

12A and 12B are diagrams showing an example of a method of moving the coil belt 1060 according to this embodiment. As shown in FIG. 12, the drawer section 1007 moves the coil belt 1060 by moving on rails 1009a to 1009h (hereinafter referred to as rail 1009 unless otherwise specified) provided on the ceiling surface of the mount 9. The drawer section 1007 has, for example, a motor and an encoder (not shown), and moves the coil belt 1060 under the control of the movement control function 123d. The lead-out portion 1007 is an example of a coil moving mechanism in this embodiment.

Although the coil belt 1060 is pulled out from the coil outlet 91b in FIG. 12, the coil belt 1060 may be pulled out from either of the coil outlets 91a and 91b.

Next, the flow of coil setting and imaging processing performed by the magnetic resonance imaging apparatus 100 configured as described above will be described.

FIG. 13 is a flowchart showing an example of the flow of coil setting and imaging processing according to this embodiment. The processing from the acquisition of the imaging conditions in S1 to the process of specifying the combination of the coil elements 6 attached to the subject in S11 and the installation target position 901 is the same as in the first embodiment.

Next, the movement control function 123d of this embodiment controls the drawing unit 1007 to take out the coil belt 1060 including the coil element 6 specified by the specifying function 123c from the lower part of the gantry 9, and attach the coil belt to the subject P. 1060 is attached (S12).

FIG. 14 is a diagram showing an example of movement of the coil belt 1060 according to the present embodiment in chronological order. As shown in the first drawing from the left in FIG. 14 , the drawing section 1007 moves on the rail 1009 to draw out the coil belt 1060 . In addition, as shown in the middle diagram of FIG. 14, the pedestal 9 has locking portions 1017 for locking the drawer portion 1007 at a desired position. In the example shown in FIG. 14, the locking portion 1017 is provided at the end point of the rail 1009, but the locking portion 1017 may be provided in the middle of the rail 1009 so that the coil belt 1060 can be locked. .

Then, the movement control function 123d of this embodiment controls the fitting plate 1027a or the fitting plate 1027b to slide toward the subject P (S202).

As shown in the first drawing from the left and the middle drawing in FIG. It is stored in a folded state on the side of the

14, the fitting plates 1027a and 1027b are slid toward the subject P under the control of the movement control function 123d, and are laterally moved along the coil belt 1060. As shown in FIG. The coil belt 1060 is brought into close contact with the subject P by applying pressure from the coil belt 1060 . For example, the fitting plate 1027 is provided with a pressure sensor and stops when it is detected that the tip reaches the subject P. FIG. The fitting plate 1027 is an example of a pressing portion in this embodiment. Note that the means for pressing the coil belt 1060 is not limited to the fitting plate 1027 . For example, a configuration in which pressure is applied from above the subject P may be employed as the pressing section.

Further, the processing from the imaging of the sensitivity map in S13 to the determination of whether or not the imaging in S18 is finished is the same as in the first embodiment.

Then, the movement control function 123d stores the fitting plate 1027 on the side surface of the gantry 9 when the imaging is completed (S203). Further, the movement control function 123d stores the coil belt 1060 inside the mount 9 (S204).

The movement of the top plate 106a in S20 is the same as in the first embodiment. Here, the processing of this flowchart ends.

Thus, in the magnetic resonance imaging apparatus 100 of the present embodiment, the storage location (storage unit) for the coil is provided inside the gantry 9 . Therefore, according to the magnetic resonance imaging apparatus 100 of this embodiment, it is possible to further reduce the space for storing the high-frequency coil (the coil belt 1060 or the coil element 6 in this embodiment). Therefore, even when it is difficult to secure a large space for the imaging room, it becomes easy to install the magnetic resonance imaging apparatus 100 of the present embodiment.

In addition, the magnetic resonance imaging apparatus 100 of this embodiment controls the fitting plate 1027 that applies pressure to the high-frequency coil (the coil belt 1060 or the coil element 6 in this embodiment) from above or from the lateral direction, and controls the high-frequency coil. is brought into close contact with the subject P. Therefore, according to the magnetic resonance imaging apparatus 100 of this embodiment, MR signals can be acquired with high accuracy, and the accuracy of magnetic resonance images can be improved.

For example, conventionally, an operator such as an engineer manually attaches a high-frequency coil such as a phased array coil to a subject so as to be in close contact with the subject. In such a case, it may take a long time for an unskilled worker to complete the installation work. In contrast, the magnetic resonance imaging apparatus 100 of the present embodiment automatically brings the high-frequency coil into close contact with the subject P, so that the workload and work time of the operator can be reduced.

In this embodiment, the specifying function 123c specifies the coil element 6 as in the first embodiment, but it may specify the coil belt 1060 as well. In this case, the lower limit of the number of coil belts 1060 in the Z-axis direction is registered in the coil number information 1221 in association with the acceleration factor. When adopting this configuration, the specific function 123c is, for example, equal to or greater than the lower limit value of the number of coil belts 1060 in the Z-axis direction defined in the coil number information 1221, and can cover the FOV 900. Among possible combinations of coil belts 1060, a combination that minimizes the number of coil belts 1060 is specified.

(Modification 1)
In the above-described second embodiment, as described with reference to FIG. 12, the drawer portion 1007 moves on the rail 1009 provided on the ceiling surface of the pedestal 9, but the method of moving the coil belt 1060 is It is not limited to this.

FIG. 15 is a diagram showing an example of a method of moving the coil belt 1060 according to this modification. For example, in this modification, the magnetic resonance imaging apparatus 100 includes one pole 1037 and multiple coil belts 1060 connectable to the pole 1037 . Of the multiple coil belts 1060 , only one or multiple coil belts 1060 used for imaging are connected to the pole 1037 . One or more connected coil belts 1060 are pulled out from a storage location (storage section) as the pole 1037 moves.

In the example shown in FIG. 15, each of the coil belts 1060d and 1060e used for imaging is connected to one pole 1037 and pulled out as the pole 1037 moves. When adopting this configuration, a moving mechanism 1047 for moving the pole 1037 is provided on the rear side of the pedestal 9 . In this modified example, the pole 1037 and the moving mechanism 1047 are an example of the coil moving mechanism.

Also, the magnetic resonance imaging apparatus 100 may have a plurality of poles 1037 . For example, FIG. 16 is a diagram showing another example of the method of moving the coil belt 1060 according to this modified example. As shown in FIG. 16, each of the coil belts 1060d, 1060e may be connected to separate poles 1037d, 1037e, respectively, and pulled out as the poles 1037d, 1037e move.

It should be noted that the method of moving the coil belt 1060 described in the second embodiment and this modified example is merely an example, and another method of moving may be employed.

(Modification 2)
Further, the magnetic resonance imaging apparatus 100 may further have a function of installing a coil element for decoupling on the subject P. FIG. For example, when coupling occurs between adjacent coil elements 6 that constitute the phased array coil 60, a high frequency current flowing in one coil element 6 causes a high frequency current, that is, an induced current to flow in the other coil elements 6. As a result, the SNR of the magnetic resonance image may be degraded. Therefore, by arranging a decoupling coil element at the boundary between the adjacent coil elements 6 so as to overlap the adjacent coil elements 6, such a decrease in SNR can be suppressed.

FIG. 17 is an example of a horizontal cross-sectional view of the gantry 9 according to this modified example. For example, the movement control function 123d controls the coil arm 7 so that decoupling coil elements 2006a and 2006b (hereinafter, unless otherwise simply referred to as coil element 2006 for decoupling) are superimposed and installed. The example shown in FIG. 17 is a modification of the configuration of the first embodiment, but the second embodiment may be combined with a configuration in which coil elements 2006 for decoupling are installed.

(Modification 3)
In each of the above-described embodiments, the phased array coil 60 is configured by combining the plurality of coil elements 6 according to the FOV 900 and the acceleration factor. The phased array coil 60 may be housed in the coil box 5 . For example, it is assumed that the phased array coil 60 is prepared in advance for each imaging region. In this modified example, the phased array coil 60 is an example of a high frequency coil.

In this modified example, the storage circuit 122 stores, for example, an imaging region and region-specific phased array coil information in which each of the plurality of phased array coils 60 is associated with the imaging region. Further, the specifying function 123c selects the phased array coil 60 to be used for examination of the subject P based on the imaged region received by the receiving function 123a and the region-by-region phased array coil information stored in the storage circuit 122, for example. Identify. The part-by-part phased array coil information is an example of the part-by-part coil information in this modified example.

Further, in this modification, the movement control function 123d controls the coil arm 7 to move the specified phased array coil 60 from the coil box 5 to a position covering the FOV 900 of the subject P.

According to the magnetic resonance imaging apparatus 100 of this modified example, even when the phased array coil 60 in which a plurality of coil elements 6 are pre-combined for each imaging region is used, the selection and attachment of the phased array coil 60 are automatically performed. Therefore, the work time required for coil setting and the work load can be reduced.

(Modification 4)
Further, in each of the above-described embodiments, parallel imaging by the phased array coil 60 is assumed, but parallel imaging may not be performed.

For example, in this modified example, instead of the phased array coil 60, a local high-frequency coil (surface coil) prepared for each imaging region may be used. Local high-frequency coils include, for example, a head receiving coil, a neck receiving coil, a shoulder receiving coil, a chest receiving coil, an abdominal receiving coil, and a leg receiving coil. In this modified example, the local high-frequency coil is an example of the high-frequency coil.

The local high-frequency coil may further have a transmission function of applying an RF magnetic field. In that case, the local radio frequency coil is connected to the transmission circuit 108 and applies an RF magnetic field to the subject P based on the RF pulse signal output from the transmission circuit 108 .

In this modified example, the storage circuit 122 stores, for example, region-specific local coil information in which imaging regions and local high-frequency coils are associated with each other. Further, the specifying function 123c specifies a local high-frequency coil to be used for examination of the subject P, for example, based on the imaged region received by the receiving function 123a and the region-specific local coil information. The site-specific local coil information is an example of the site-specific coil information in this modified example.

In addition, in this modification, the movement control function 123d controls the coil arm 7 to move the identified local high-frequency coil from the coil box 5 to a position covering the FOV 900 of the subject P. FIG.

According to the magnetic resonance imaging apparatus 100 of the present modification, even when a local high-frequency coil prepared for each imaging region is used, selection and attachment of the local high-frequency coil are automatically performed. Working time and workload can be reduced.

According to at least one embodiment described above, it is possible to reduce the work time and work load required for attaching the high-frequency coil.

While several embodiments of the invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, as well as the scope of the invention described in the claims and equivalents thereof.

5 Coil Box 6, 6a-6n Coil Element 7 Coil Arm 9 Base 51, 51a-51d Rail 60 Phased Array Coil 100 Magnetic Resonance Imaging Apparatus 101 Static Magnetic Field Magnet 102 Gradient Magnetic Field Coil 103 Gradient Magnetic Field Power Supply 106 Bed 106a Top Board 107 Bed Control Circuit 108 Transmission Circuit 109 Reception Circuit 110 Sequence Control Circuit 120 Computer System 121 Interface Circuit 122 Storage Circuit 123a Receiving Function 123b Imaging Function 123c Specific Function 123d Movement Control Function 123e Image Generation Function 123f Display Control Function 124 Input Interface 125 Display 160a Tabletop 1007 Drawer section 1027, 1027a, 1027b Fitting plate 1037, 1037d, 1037e Pole 1047 Moving mechanism 1060, 1060d, 1060e Coil belt 1221 Coil number information 2006a, 2006b Coil element for decoupling C Magnetic field center P Subject

Claims (11)

a coil moving mechanism that moves a high-frequency coil that receives an MR (Magnet Resonance) signal from a subject so that it can be retracted from an imaging position;
a specifying unit that specifies a high-frequency coil to be used for inspection of the subject according to imaging conditions;
a control unit that controls the movement of the coil moving mechanism in the Z-axis direction and the Y-axis direction so as to move the high-frequency coil specified by the specifying unit from the retracted position to the imaging position;
with
The high-frequency coil has a plurality of coil elements that function as phased array coils, and the specifying unit specifies the coil elements to be used for the inspection according to the imaging conditions,
After moving the coil element specified by the specifying unit from the retracted position to the imaging position, the control unit causes a boundary between adjacent coil elements forming the phased array coil to overlap the adjacent coil element. move the coil element for decoupling so that
Magnetic resonance imaging equipment. A coil moving mechanism that moves a high-frequency coil that receives an MR (Magnet Resonance) signal from a subject so that it can be retracted from an imaging position, and a specification that specifies the high-frequency coil used for examination of the subject according to imaging conditions. a control unit that controls the coil moving mechanism to move the high-frequency coil specified by the specifying unit from the retracted position to the imaging position;
with
The imaging condition is at least one of an imaging site, an imaging field of view, and an acceleration factor for parallel imaging, and the high-frequency coil has a plurality of coil elements functioning as a phased array coil,
The specifying unit selects the coils to be used for the examination based on the number of coils information in which the acceleration factor and the lower limit of the number of coil elements installed in the subject are associated with each other, and the dimension of the imaging field of view. The element is specified, and the number of the coil elements is the smallest among the combinations of the coil elements that are equal to or greater than the lower limit of the number of the coil elements defined in the information on the number of coils and that can cover the imaging field of view. A magnetic resonance imaging device that identifies a combination that The control unit controls movement in the Z-axis direction and the Y-axis direction,
3. The magnetic resonance imaging apparatus according to claim 2. The control unit controls movement in the X-axis direction,
The magnetic resonance imaging apparatus according to claim 1 or 3 . The high-frequency coil has a plurality of coil elements that function as phased array coils, and the specifying unit specifies the coil elements to be used for the inspection according to the imaging conditions,
After moving the coil element specified by the specifying unit from the retracted position to the imaging position, the control unit causes a boundary between adjacent coil elements forming the phased array coil to overlap the adjacent coil element. move the coil element for decoupling so that
3. The magnetic resonance imaging apparatus according to claim 2 . further comprising a storage unit that stores the high-frequency coil,
The coil moving mechanism stores the high-frequency coil in the storage unit when retracting the high-frequency coil from the imaging position.
The magnetic resonance imaging apparatus according to claim 1 or 2 . The imaging condition is at least one of an imaging site, an imaging field of view, and an acceleration factor for parallel imaging, and the high-frequency coil has a plurality of coil elements functioning as a phased array coil,
The specifying unit selects the coils to be used for the examination based on the number of coils information in which the acceleration factor and the lower limit of the number of coil elements installed in the subject are associated with each other, and the dimension of the imaging field of view. The element is specified, and the number of the coil elements is the smallest among the combinations of the coil elements that are equal to or greater than the lower limit of the number of the coil elements defined in the information on the number of coils and that can cover the imaging field of view. identify the combinations that result in
The magnetic resonance imaging apparatus according to claim 1. The lower limit of the number of coil elements is the installed number of the coil elements at which the g-factor is equal to or less than a predetermined value in imaging with the acceleration factor.
The magnetic resonance imaging apparatus according to claim 2 or 7 . The storage unit is located behind the pedestal of the magnetic resonance imaging apparatus,
7. A magnetic resonance imaging apparatus according to claim 6 . The storage unit is provided inside the pedestal of the magnetic resonance imaging apparatus,
7. A magnetic resonance imaging apparatus according to claim 6 . 11. The control unit according to any one of claims 1 to 10 , wherein the control unit controls a pressing unit that applies pressure to the high-frequency coil from above or from a lateral direction to bring the high-frequency coil into close contact with the subject. magnetic resonance imaging equipment.

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