JP5484272B2 - Magnetic resonance imaging apparatus and receiving coil connection state confirmation method - Google Patents

Description

  The present invention measures nuclear magnetic resonance (hereinafter referred to as “NMR”) signals from hydrogen, phosphorus, etc. in a subject, and images nuclear density distribution, relaxation time distribution, etc. In particular, the present invention relates to a method for confirming a receiving coil connection state.

  The MRI apparatus measures NMR signals generated by nuclear spins constituting a subject, particularly a human tissue, and images the form and function of the head, abdomen, limbs, etc. two-dimensionally or three-dimensionally. Device. In imaging, the NMR signal is given different phase encoding depending on the gradient magnetic field and is frequency-encoded and measured as time-series data. The measured NMR signal is reconstructed into an image by two-dimensional or three-dimensional Fourier transform.

When imaging with such an MRI apparatus, a method of acquiring an image by connecting an optimal receiving surface coil for each imaging target region (hereinafter referred to as “method 1”) and a surface coil are connected. There is a method of acquiring an image using a built-in coil for both transmission and reception (hereinafter referred to as “method 2”).
As a method for recognizing the connection state of the receiving coil used for imaging, as shown in Patent Document 1 and Patent Document 2, there is a method of using an accompanying number of the surface coil being connected.

JP-A-2-57938 JP-A-6-201809

When the user tries to take an image, the following two cases can be considered as a state where the surface coil is not connected to the MRI apparatus.
Case 1: Although the user intends to perform imaging in “Method 1” (that is, a method of acquiring an image by connecting an optimal receiving surface coil for each imaging target region), at the time of imaging start The surface coil is in poor connection.
Case 2: A state where the user intends to take an image in “Method 2” (that is, a method of acquiring an image using a built-in coil for both transmission and reception without connecting a surface coil).

  If measurement is performed by determining the state of case 1 as the state of case 2, it is determined that the image is acquired without connecting the surface coil, although the image is acquired by connecting the surface coil. Therefore, the image intended by the user cannot be obtained, and time is wasted.

  In order to avoid this, it is necessary for the user to select the built-in coil in advance from the list of receiving coils in order to clearly indicate the case 2 state, which makes the operation complicated. There was a problem.

  Therefore, an object of the present invention is to provide a means for easily performing imaging with a receiving coil intended by a user when the user tries to perform imaging in a state where a surface coil is not connected.

  In order to achieve the above object, the outline of typical ones of the present invention will be briefly described as follows.

  A magnetic field is generated in a magnetic resonance imaging apparatus that irradiates a subject placed in a magnetic field space with a high frequency and acquires an image of an imaging region of the subject based on a nuclear magnetic resonance signal emitted from the subject. Static magnetic field generating means, irradiation means for irradiating a subject placed in a static magnetic field space with high frequency, gradient magnetic field generating means for applying a gradient magnetic field superimposed on the static magnetic field space, static magnetic field generating means and gradient magnetic field generation An exterior cover covering the means; a receiving means for receiving a nuclear magnetic resonance signal emitted from the subject; a control means for controlling the operation of the receiving means; and a display means for displaying information used for the control means. The means has a built-in coil arranged on the imaging space side that images the subject inside the exterior cover and a surface coil that can be attached and detached according to the imaging object and imaging conditions. Resonance A connection state determination unit that determines a connection state of whether or not the device is connected to the gazing device, and a presentation unit that presents a selection request for whether or not to capture an image with the built-in coil. When the control means determines that the surface coil is not connected by the connection state determination means, the presenting means presents a request for selecting whether or not to take an image with the built-in coil, and if the image is not taken with the internal coil, The magnetic resonance imaging apparatus has means for giving the user an improvement opportunity to return to the connection state intended by the user when selected.

  Alternatively, a static magnetic field generating means for generating a static magnetic field space, an irradiation means for irradiating a subject placed in the static magnetic field space with a high frequency, a gradient magnetic field generating means for applying a gradient magnetic field superimposed on the static magnetic field space, An outer cover that covers the static magnetic field generating means and the gradient magnetic field generating means, a built-in coil disposed on the imaging space side that images the subject inside the outer cover, and a surface coil that can be detached according to the imaging target and imaging conditions A receiving means for receiving a nuclear magnetic resonance signal provided from the subject, a control means for controlling the operation of the receiving means, a display means for displaying information used for the control means, and an information holding means for holding information; A method for confirming a connection state of a receiving coil in a magnetic resonance imaging apparatus comprising: a control means for determining whether or not a surface coil is connected to the magnetic resonance imaging apparatus And a step of presenting a selection request as to whether or not to take an image with the built-in coil to the display means. When imaging is started by the user, the control means determines whether the surface coil is in the step of determining the connection state. If it is determined that the connection is not established, the display means presents a request for selecting whether or not to capture an image with the built-in coil. It is the confirmation method of the receiving coil connection state characterized by including the step to reset.

  In other words, when the user tries to take an image, the apparatus has a means for easily taking an image with the intended receiving coil based on the connection state of the receiving coil.

  According to the MRI apparatus of the present invention, when imaging is to be performed, it is possible to quickly check whether the connection state of the surface coil is as intended by the user, and to easily select the receiving coil used for imaging. become.

The figure which shows the flow of the process in 1st Embodiment. 1 is an overall basic configuration diagram of an MRI apparatus according to the present invention. The figure which shows the whole fundamental structure which concerns on 1st Embodiment. The figure which shows the whole fundamental structure which concerns on 2nd Embodiment. The figure which shows the flow of a process in 2nd Embodiment. The figure which shows the whole fundamental structure which concerns on 3rd Embodiment. The figure which shows the flow of a process in 3rd Embodiment.

  Hereinafter, preferred embodiments of the MRI apparatus of the present invention will be described in detail with reference to the accompanying drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiments of the invention, and the repetitive description thereof is omitted.

First, an overall outline of an example of an MRI apparatus according to the present invention will be described with reference to FIG.
FIG. 2 is a block diagram showing the overall configuration of an embodiment of the MRI apparatus according to the present invention. This MRI apparatus uses a NMR phenomenon to obtain a tomographic image of a subject. As shown in FIG. 2, the MRI apparatus includes a static magnetic field generation system 2, a gradient magnetic field generation system 3, a transmission system 5, A reception system 6, a signal processing system 7, a sequencer 4, and a central processing unit (CPU) 8 are provided.

  The static magnetic field generation system 2 includes static magnetic field generation means, and the gradient magnetic field generation system 3 includes gradient magnetic field generation means. The static magnetic field generating means and the gradient magnetic field generating means are covered with a gantry exterior cover (not shown).

  The static magnetic field generation system 2 generates a uniform static magnetic field in the direction perpendicular to the body axis in the space around the subject 1 if the vertical magnetic field method is used, and in the direction of the body axis if the horizontal magnetic field method is used. Thus, a permanent magnet type, normal conducting type or superconducting type static magnetic field generating source is arranged around the subject 1.

  The gradient magnetic field generation system 3 includes a gradient magnetic field coil 9 wound in the three-axis directions of X, Y, and Z, which is a coordinate system (stationary coordinate system) of the MRI apparatus, and a gradient magnetic field power source 10 that drives each gradient magnetic field coil. The gradient magnetic fields Gx, Gy, Gz are applied in the three axial directions of X, Y, Z by driving the gradient magnetic field power supply 10 of each coil in accordance with a command from the sequencer 4 described later. At the time of imaging, a slice direction gradient magnetic field pulse (Gs) is applied in a direction orthogonal to the slice plane (imaging cross section) to set a slice plane for the subject 1, and the remaining two orthogonal to the slice plane and orthogonal to each other A phase encoding direction gradient magnetic field pulse (Gp) and a frequency encoding direction gradient magnetic field pulse (Gf) are applied in one direction, and position information in each direction is encoded in the echo signal.

  The sequencer 4 is a control unit that repeatedly applies a high-frequency magnetic field pulse (hereinafter referred to as “RF pulse”) and a gradient magnetic field pulse in a predetermined pulse sequence, and operates under the control of the CPU 8 to collect tomographic image data of the subject 1. Various commands necessary for the transmission are sent to the transmission system 5, the gradient magnetic field generation system 3, and the reception system 6.

The transmission system 5 irradiates the subject 1 with RF pulses in order to cause nuclear magnetic resonance to occur in the nuclear spins of the atoms constituting the living tissue of the subject 1, and includes a high-frequency oscillator 11, a modulator 12, and a high-frequency amplifier. 13 and a high frequency coil (transmission coil) 14a on the transmission side incorporated in the apparatus. The high-frequency pulse output from the high-frequency oscillator 11 is amplitude-modulated by the modulator 12 at a timing according to a command from the sequencer 4, and the amplitude-modulated high-frequency pulse is amplified by the high-frequency amplifier 13 and then placed close to the subject 1. By supplying to the high frequency coil 14a, the subject 1 is irradiated with the RF pulse.
Here, the high-frequency coil 14a on the transmission side can also be used as the same function as the high-frequency coil (reception coil) 14b on the reception side described below.

  The receiving system 6 detects an echo signal (NMR signal) emitted by nuclear magnetic resonance of nuclear spins constituting the biological tissue of the subject 1, and receives a high-frequency coil (receiving coil) 14b and a signal amplifier 15 on the receiving side. And a quadrature phase detector 16 and an A / D converter 17.

  The receiving coil is built inside the outer cover of the gantry, that is, on the imaging space side where the subject 1 is imaged. Hereinafter, the coil in such a built-in state is referred to as a built-in coil.

After the NMR signal of the response of the subject 1 induced by the electromagnetic wave irradiated from the high frequency coil 14a on the transmission side is detected by the high frequency coil 14b arranged close to the subject 1 and amplified by the signal amplifier 15, The quadrature phase detector 16 divides the signal into two orthogonal signals at a timing according to a command from the sequencer 4, and each signal is converted into a digital quantity by the A / D converter 17 and sent to the signal processing system 7.
Note that the high-frequency coil 14b on the receiving side can be connected by changing the type according to the measurement site of the subject.

  The signal processing system 7 performs various data processing and display and storage of processing results. The signal processing system 7 includes an external storage device such as an optical disk 19 and a magnetic disk 18 and a display 20 including a CRT. Is input to the CPU 8, the CPU 8 executes processing such as signal processing and image reconstruction, and displays the tomographic image of the subject 1 as a result on the display 20, and also the magnetic disk 18 of the external storage device. Record in etc.

  The operation unit 25 is used to input various control information of the MRI apparatus and control information of processing performed by the signal processing system 7 and includes a trackball or mouse 23 and a keyboard 24. The operation unit 25 is disposed close to the display 20, and the operator controls various processes of the MRI apparatus interactively through the operation unit 25 while looking at the display 20.

  In FIG. 2, the high-frequency coil 14a and the gradient magnetic field coil 9 on the transmission side are opposed to the subject 1 in the static magnetic field space of the static magnetic field generation system 2 in which the subject 1 is inserted. If the horizontal magnetic field method is used, the subject 1 is installed so as to surround it. The high-frequency coil 14b on the receiving side is installed so as to face or surround the subject 1.

  Currently, the radionuclide to be imaged by the MRI apparatus is a hydrogen nucleus (proton) that is a main constituent material of the subject as being widely used clinically. Information on the spatial distribution of the proton density and the spatial distribution of the relaxation time of the excited state is imaged, thereby imaging the form or function of the human head, abdomen, limbs, etc. two-dimensionally or three-dimensionally.

Next, a method for imaging an examination site using the MRI apparatus as described above will be described with reference to FIG. When imaging is performed, first, the subject 31 is placed on the top board 46a. At this time, when imaging by the above-mentioned “method 1” is performed, the surface coil 37 is also arranged in accordance with the examination site and connected to the signal detection unit 38. Thereafter, the top board 46a is moved so that the examination site matches the light marker 47 attached to the magnet 32. In this state, by using the operation panel 48 attached to the magnet 32, the examination region is arranged in the static magnetic field space by moving a certain distance from the light marker 47 to the center of the magnet 32.
<First Embodiment>
Next, a first embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 shows a processing flow of the present embodiment. In addition, the number in the parenthesis shown below shows each step number shown in the figure.

First, imaging by the user is started (101). Subsequently, the system checks whether a surface coil is connected to the MRI apparatus (102). If not connected, the process proceeds to “None” in the figure, and it is confirmed whether or not to perform imaging with the built-in coil (103). Here, when proceeding to “Imaging” in the drawing, that is, when imaging with the built-in coil, the routine proceeds to “Imaging start” and imaging is started (105). On the other hand, when the process proceeds to “do not image” in the figure, that is, when the internal coil is not imaged, the process proceeds to step (104) where the user improves the connection state. Here, the improvement of the connection state means returning to the connection state intended by the user from the current state.
If the process proceeds to “Yes” in the step 102, the process proceeds to “Start imaging” and starts imaging (105).
The above processing is executed by the system, that is, by the processing of the central processing unit 8, based on a program stored in the signal processing system 7 in advance. Note that the “improvement of connection state” is performed by the user confirming the state on the screen displayed on the display 20 and giving an improvement instruction according to the user's intention.

  The storage device 41 and the display device 42 shown in FIG. 3 correspond to the function group executed by the signal processing system 7 shown in FIG. 2, and the computer 43, the signal processing unit 39, and the control device 45 are shown in FIG. This corresponds to a function group executed by the central processing unit (CPU) 8.

As is clear from the above processing flow, when the user starts imaging, the system determines whether there is a surface coil connected to the MRI apparatus. At this time, when the surface coil is not connected, a confirmation screen as to whether or not to perform imaging with the built-in coil is displayed. When the user intends to perform imaging by the above-described “method 1”, since the connection failure of the surface coil can be recognized at this time, the connection state can be improved. In addition, when the user intends to perform imaging by the “method 2”, it is possible to easily perform imaging by instructing imaging on the confirmation screen.
<Second Embodiment>
Next, a second embodiment will be described with reference to the drawings.

  In this embodiment, in addition to the first embodiment, a warning device 49 is installed near the operation panel 48 as shown in FIG.

  The difference from the first embodiment is that it is possible to recognize a connection failure of the surface coil before the user starts imaging. Hereinafter, only different portions will be described, and description of the same portions will be omitted.

  When the user uses the operation panel 48 shown in FIG. 4 to place the examination site in the static magnetic field space, the computer 43 determines the presence or absence of the surface coil 37 connected to the MRI apparatus. At this time, if the surface coil 37 is not connected, the warning device 49 notifies the user that the surface coil 37 is not connected. When the user intends to perform imaging by the above-described “method 1”, since the connection failure of the surface coil 37 can be recognized at this time, the connection state can be improved. In addition, when the user intends to perform the above-described “method 2” imaging, the imaging can be easily performed with the built-in coil by ignoring the warning display and starting the imaging.

  The correspondence between the storage device 41, the display device 42, the computer 43, the signal processing unit 39, and the control device 45 shown in FIG. 4 and FIG. 2 is the same as that in the first embodiment.

  FIG. 5 shows a processing flow of the present embodiment. In addition, the number in the parenthesis shown below shows each step number shown in the figure.

  First, the arrangement of the examination site of the subject 31 is confirmed (501). Subsequently, the system checks whether a surface coil is connected to the MRI apparatus (502). If not connected, the process proceeds to “None” in the figure, and a “No connection” warning is displayed on the warning device 49 shown in FIG. 4 (503).

  Further, the process proceeds to the next step 504. Here, the user determines the imaging method. That is, it is determined whether to use the above-described “method 1” or “method 2”. When proceeding to “Method 1” in the figure, the connection state is improved by the user (505). Next, the imaging start is selected by the user (506), the process proceeds to “imaging start”, and imaging is started (507).

  On the other hand, when proceeding to “Method 2” in the figure, the user selects start of imaging (506), proceeds to “Start imaging”, and starts imaging (507).

In step 502, the user selects start of imaging (506), and imaging starts (507).
The above processing is executed by the system, that is, by the processing of the central processing unit 8, based on a program stored in the signal processing system 7 in advance.
<Third Embodiment>
Next, a third embodiment will be described with reference to the drawings. The difference from the first embodiment and the second embodiment is that the system automatically determines the imaging method of “Method 1” and “Method 2” described above. Hereinafter, only different portions will be described, and description of the same portions will be omitted.

  In the present embodiment, in addition to the second embodiment, a marker 50 is installed on the surface coil 37 as shown in FIG. 6, and a camera 51 for photographing the inside of the static magnetic field space is installed.

  The user uses the operation panel 48 shown in FIG. 6 to place the examination site in the static magnetic field space. At this time, the computer 43 determines whether or not there is a surface coil connected to the MRI apparatus, and determines whether or not there is a surface coil in the static magnetic field space based on the presence or absence of the marker 50 in the signal from the camera 51. At this time, when there is no surface coil connected and there is a surface coil in the static magnetic field space, the connection failure of the surface coil occurs even though the imaging method of “Method 1” is intended. The warning device 49 notifies the user that a surface coil connection failure has occurred.

  Further, when the user starts imaging, the computer 43 determines whether or not there is a surface coil connected to the MRI apparatus, and whether or not there is a surface coil in the static magnetic field space according to the presence or absence of the marker 50 in the signal from the camera 51. Judging. At this time, when there is no surface coil connected and there is no surface coil in the static magnetic field space, it is determined that the imaging method is based on the “method 2”, and imaging is automatically performed with the built-in coil.

  The correspondence between the storage device 41, the display device 42, the computer 43, the signal processing unit 39, and the control device 45 shown in FIG. 6 and FIG. 2 is the same as that in the first embodiment.

  FIG. 7 shows a processing flow of the present embodiment. In addition, the number in the parenthesis shown below shows each step number shown in the figure.

  First, confirmation of the arrangement of the examination region of the subject 31 is started (701). Subsequently, the system checks whether the surface coil 37 is connected to the MRI apparatus (702). If not connected, the process proceeds to “None” in the figure, and the presence or absence of the surface coil marker 50 is confirmed (703). If the marker 50 is present, the process proceeds to “Yes” in the figure, and a connection failure warning is displayed (704). Next, the system determines that the user intends “method 1”, and the connection state is improved by the user (705). Thereafter, imaging by the user is started (706).

  If there is no marker 50 in step 703, the process proceeds to “No” in the figure, and imaging by the user is started (706).

  Next, when the user starts imaging (706), it is subsequently confirmed whether or not the surface coil 37 is connected to the MRI apparatus (707). If not connected, the process proceeds to “None” in the figure, and the presence or absence of the surface coil marker 50 is confirmed (708). If there is no marker 50, the process proceeds to “None” in the figure, and the built-in coil is automatically selected (709). When the selection of the built-in coil is completed, the process proceeds to “start imaging” and imaging starts (710).

On the other hand, if there is a marker 50, the process proceeds to “Yes” in the figure, and imaging is stopped (711).
After proceeding to step 711 of “Imaging stop”, the process proceeds to “improvement of connection state by user” in step 705, and the user sets the connection state intended by the user. After the improvement of the connection state is completed, the process proceeds to step 706.

Further, it is confirmed whether or not the surface coil 37 is connected to the MRI apparatus (707). If it is connected, the process proceeds to “Yes” in the figure and imaging is started (710).
The above processing is executed by the system, that is, by the processing of the central processing unit 8, based on a program stored in the signal processing system 7 in advance.

DESCRIPTION OF SYMBOLS 1 ... Subject, 2 ... Static magnetic field generation system, 3 ... Gradient magnetic field generation system, 4 ... Sequencer, 5 ... Transmission system, 6 ... Reception system, 7 ... Signal processing system, 8 ... Central processing unit (CPU), 9 ... Gradient magnetic field coil, 10 Gradient magnetic field power source, 11 High frequency transmitter, 12 Modulator, 13 High frequency amplifier, 14 a High frequency coil (transmitting coil), 14 b High frequency coil (receiving coil), 15 Signal amplifier, 16 ... Quadrature detector, 17 ... A / D converter, 18 ... Magnetic disk, 19 ... Optical disk, 20 ... Display, 21 ... ROM, 22 ... RAM, 23 ... Trackball or mouse, 24 ... Keyboard, 31 ... Subject , 32 ... magnet, 33 ... gradient magnetic field coil, 34 ... gradient magnetic field power supply, 35 ... RF oscillation coil, 36 ... RF transmitter, 37 ... surface coil, 38 ... signal detector, 39 ... signal processor, 40 ... Kensa, 41 ... Storage device, 42 ... Display device, 43 ... Computer, 44 ... Top plate moving device, 45 ... Control device, 46 ... Bed, 46a ... Top plate, 47 ... Light marker, 48 ... Control panel, 49 ... Warning Device, 50 ... marker, 51 ... camera.

Claims (7)

Receiving means for receiving a nuclear magnetic resonance signal emitted from the subject with a built-in coil and a removable surface coil ;
And determining the connection state determining means for determining whether a connection state wherein the surface coil is connected to the magnetic resonance imaging apparatus,
When the surface coil is determined not to be connected by the connection state detecting means includes presenting means for presenting one of the selection request whether imaging in the previous SL internal coil,
Means for giving the user an opportunity to improve the connection state intended by the user when the user selects not to image with the built-in coil ;
A magnetic resonance imaging apparatus comprising: The magnetic resonance imaging apparatus according to claim 1.
The restoration of the connection state is executed by setting of imaging using the surface coil on the display of the display means. The magnetic resonance imaging apparatus according to claim 1 or 2 ,
The request for selecting whether or not to capture an image with the built-in coil is displayed on the display means. The magnetic resonance imaging apparatus according to any one of claims 1 to 3 ,
When it is determined that the surface coil is not connected, the magnetic resonance imaging apparatus includes means for warning the connection state of the surface coil when the examination site of the subject is installed. The magnetic resonance imaging apparatus according to any one of claims 1 to 4 ,
The time of imaging, magnetic resonance imaging apparatus characterized by imaging in the internal coil and the control means determines. The magnetic resonance imaging apparatus according to any one of claims 1 to 5 ,
Wherein when setting the inspection region of the object, a magnetic resonance imaging apparatus, characterized in that said control means poor connection of the surface coil is determined. It is the built-coil and removable surface coils Re et al provided a receiving means for receiving the nuclear magnetic resonance signal emitted from the subject,
Determining whether or not the connection state prior Symbol surface coil is connected to the magnetic resonance imaging apparatus,
When it is determined that the surface coils in determining the pre-SL connection state is not connected, and presenting the one of selection request whether imaging in the previous SL internal coil,
When the user selects not to image with the built-in coil, the step of returning to a connection state intended by the user ;
A method for confirming a connection state of a receiving coil in a magnetic resonance imaging apparatus .

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