JP5086796B2 - Magnetic resonance imaging apparatus, magnetic resonance imaging maintenance apparatus, magnetic resonance imaging maintenance system, and magnetic resonance imaging apparatus inspection method - Google Patents

Description

  The present invention relates to a coil inspection technique for a magnetic resonance imaging apparatus capable of changing a combination of element coils that receive magnetic resonance signals and assigning them to channels.

  Magnetic resonance imaging performed by a magnetic resonance imaging (MRI) apparatus magnetically excites a subject's nuclear spin placed in a static magnetic field with a high-frequency signal of its Larmor frequency, and is generated along with this excitation. This is an imaging method in which an image is reconstructed from magnetic resonance (MR) signals.

  In order to execute this imaging method, the magnetic resonance imaging apparatus includes a static magnetic field magnet that generates a static magnetic field, and a mechanism that applies a gradient magnetic field pulse and a high-frequency magnetic field pulse to a subject according to a predetermined pulse sequence. Among these, the gradient magnetic field pulse is transmitted to the subject through a gradient coil disposed in the bore of the static magnetic field magnet and connected to the gradient magnetic field power source. Similarly, the high-frequency magnetic field pulse is transmitted to the subject via a transmitting high-frequency coil disposed in the bore of the static magnetic field magnet and connected to the transmitter. On the other hand, in order to receive a magnetic resonance signal composed of a high-frequency signal generated from the subject, a receiving high-frequency coil is disposed in the vicinity of the subject. A high-frequency coil for transmission and a high-frequency coil for reception may be shared by a single coil, but in many cases, a dedicated high-frequency coil for reception corresponding to the difference in diagnostic part is used.

  That is, in order to obtain an image with high sensitivity, a plurality of surface coils (array coils) are arranged in a region of interest of a subject as a receiving high-frequency coil and imaged. For example, as described in Patent Document 1, an array coil in which QD (Quadrature Detection) surface coils are arranged in the body axis direction has been proposed as a spinal coil. Here, the QD surface coil is a coil in which a loop-type surface coil and an 8-shaped surface coil are arranged so as to overlap each other, and the S / N can be improved as compared with the case where the 8-shaped surface coil is not stacked. .

  On the other hand, when imaging the entire abdomen, as described in Patent Document 2, normally, a plurality of surface coils are arranged so as to surround the subject, and signals are received from the entire abdomen. . As this surface coil, an array coil in which a plurality of loop coils are arranged along the body surface is often used.

  In recent years, an MRI apparatus that can change the combination of a plurality of coil elements (element coils) and assign them to channels has been developed (see, for example, Patent Document 3). In such an MRI apparatus, the sensitivity distribution can be optimized for each part to be imaged by changing the combination of coil elements and assigning them to channels.

Japanese Patent Laid-Open No. 5-261810 JP 2003-334177 A JP 2006-141444 A

  However, in an MRI apparatus that can change the combination of a plurality of coil elements and assign them to channels, there is a problem that it takes a lot of time and labor to inspect the receiving high-frequency coil at the time of installation or the like.

  That is, in order to inspect all the coil elements and the parts used when combining the coil elements, it is necessary to perform imaging using all the coil element combinations and use the collected data and images. Therefore, when the number of coil elements is large, tens of thousands of combinations need to be inspected, and much time is required for the inspection.

  The present invention has been made to solve the above-described problems caused by the prior art, and shortens the inspection time as a receiving high-frequency coil when a combination of a plurality of coil elements can be changed and assigned to a channel. An object of the present invention is to provide an MRI apparatus, an MRI maintenance apparatus, an MRI maintenance system, and an MRI apparatus inspection method that can be performed.

  In order to solve the above-described problems and achieve the object, the magnetic resonance imaging apparatus according to claim 1 includes an application unit that applies a gradient magnetic field and a high-frequency pulse to a subject placed in a static magnetic field, A high-frequency coil having a plurality of element coils for detecting a magnetic resonance signal emitted from the subject in response to application of a gradient magnetic field and the high-frequency pulse; a plurality of receivers for receiving and processing the magnetic resonance signal; A magnetic resonance signal from an element coil is synthesized and input to the plurality of receivers, and a signal selection circuit having a plurality of combination modes of the magnetic resonance signal synthesis and one or a plurality of imaging sequences are being executed An imaging sequence control unit for switching a plurality of combination modes to collect magnetic resonance signals for each combination mode, and the plurality of combination modes. Based on magnetic resonance signals, the combination mode, element coils, receiver, characterized in that it comprises an abnormality specifying unit configured to specify at least one of the abnormality of the combiner for the synthesis.

  The magnetic resonance imaging maintenance apparatus according to claim 23, wherein the magnetic resonance imaging apparatus having a plurality of combined combination modes for combining the magnetic resonance signals detected by the plurality of element coils is executing one or a plurality of imaging sequences. An acquisition unit that acquires a magnetic resonance signal for each combination mode collected by switching a plurality of combination modes, and a combination mode, an element coil, a receiver, based on the magnetic resonance signal for each combination mode acquired by the acquisition unit, And an abnormality specifying unit that specifies an abnormality of at least one of the combiners for combining.

  The magnetic resonance imaging maintenance system according to claim 24, wherein an application unit that applies a gradient magnetic field and a high-frequency pulse to a subject placed in a static magnetic field, and the application of the gradient magnetic field and the high-frequency pulse A high frequency coil having a plurality of element coils for detecting magnetic resonance signals emitted from the subject, a plurality of receivers for receiving and processing the magnetic resonance signals, and a magnetic resonance signal from the plurality of element coils. The signal selection circuit having a plurality of combination modes of combining the magnetic resonance signals, and switching a plurality of combination modes during execution of one or a plurality of imaging sequences, A magnetic resonance imaging apparatus including an imaging sequence control unit for collecting magnetic resonance signals for each combination mode; An acquisition unit that acquires a magnetic resonance signal for each combination mode collected by switching the combination mode, and a combination mode, an element coil, a receiver, based on the magnetic resonance signal for each combination mode acquired by the acquisition unit, The magnetic resonance imaging maintenance apparatus includes an abnormality specifying unit that specifies an abnormality of at least one of the combiners for combining.

  Furthermore, in the magnetic resonance imaging method according to claim 25, when the electromagnetic resonance imaging apparatus having a plurality of combined combination modes for synthesizing the magnetic resonance signals detected by the plurality of element coils is executing one or a plurality of imaging sequences. A plurality of combination modes are switched, magnetic resonance signals are collected for each combination mode, and based on the magnetic resonance signals of the plurality of combination modes, combination modes, element coils, a receiver, and a combiner for combining It is characterized by identifying at least any abnormality.

  According to the present invention of claim 1, 23, 24 or 25, data is collected by changing the combination of coil elements for each echo using a pulse sequence, so that data is collected efficiently and high-frequency coil inspection is performed. Time can be shortened.

  Exemplary embodiments of a magnetic resonance imaging apparatus, a magnetic resonance imaging maintenance apparatus, a magnetic resonance imaging maintenance system, and a magnetic resonance imaging apparatus inspection method according to the present invention will be described below in detail with reference to the accompanying drawings.

  First, an RF coil (high frequency coil) inspection method according to this embodiment will be described. In the RF coil inspection method according to the present embodiment, a pulse sequence is used, a combination of coil elements and channel assignment are designated for each echo, and imaging for RF coil inspection is performed without performing phase encoding.

  As shown in FIG. 1, instead of reconstructing and synthesizing raw data for each channel, comparing the reconstructed data for each channel with reference data prepared in advance under the same imaging conditions, Perform an inspection.

  For imaging, a phantom having a signal and range sufficient to cover the sensitivity of the RF coil is used. Further, in order to accurately reproduce the image when the reference data is collected, a jig for fixing the RF coil and the phantom to a certain level is used. Further, as reference data, pre-shipment, installation, inspection, and failure are prepared in advance.

  As described above, in the RF coil inspection method according to the present embodiment, the coil element combination and the channel assignment are designated for each echo, the imaging for the RF coil inspection is performed without performing the phase encoding, and the reconfiguration data for each channel is obtained. Each coil element combination is inspected by comparing with the reference data.

  Therefore, compared with the case of inspecting using a normal image, since the phase encoding is not performed, the coil element combination can be inspected efficiently, and the inspection of many combinations of the coil elements can be performed in a short time. it can. Further, since the inspection is performed using the reconfiguration data for each channel, the coil element combination can be inspected more efficiently than in the case where the reconfiguration data for each channel is combined and inspected.

  Next, the configuration of the MRI apparatus according to the present embodiment will be described. FIG. 2 is a functional block diagram illustrating the configuration of the MRI apparatus according to the present embodiment. As shown in the figure, this MRI apparatus includes a bed part on which a subject P is placed, a static magnetic field generation part for generating a static magnetic field, a gradient magnetic field generation part for adding position information to the static magnetic field, and a high-frequency signal. A transmission / reception unit for transmitting and receiving and a control / arithmetic unit for controlling the entire system and for image reconstruction are provided.

  The static magnetic field generating unit includes a superconducting static magnetic field magnet 1 and a static magnetic field power source 2 that supplies current to the static magnetic field magnet 1, and an axis of a cylindrical opening (diagnostic space) into which the subject P is placed. A static magnetic field H0 is generated in the direction (Z-axis direction). The magnet portion is provided with a shim coil (not shown). The couch portion can be removably inserted into the opening of the static magnetic field magnet 1 with the top plate T on which the subject P is placed.

  The gradient magnetic field generating unit includes a gradient magnetic field coil unit 3 incorporated in the static magnetic field magnet 1. The gradient magnetic field coil unit 3 includes three sets (types) of x, y, z coils 3x to 3z for generating gradient magnetic fields in the X-axis direction, the Y-axis direction, and the Z-axis direction that are orthogonal to each other. The gradient magnetic field generator also includes a gradient magnetic field power supply 4 that supplies current to the x, y, and z coils 3x to 3z. The gradient magnetic field power supply 4 supplies a pulse current for generating a gradient magnetic field to the x, y, z coils 3x to 3z under the control of a sequence controller 5 described later.

  By controlling the pulse current supplied to the x, y, z coils 3x to 3z from the gradient magnetic field power source 4, the gradient magnetic fields in the three axes (X axis, Y axis, Z axis) directions which are physical axes are synthesized. The logical axis direction composed of the slice direction gradient magnetic field GS, the phase encode direction gradient magnetic field GE, and the readout direction (frequency encode direction) gradient magnetic field GR orthogonal to each other can be arbitrarily set and changed. The gradient magnetic fields in the slice direction, the phase encoding direction, and the readout direction are superimposed on the static magnetic field H0.

  The transmission / reception unit includes a transmission high-frequency coil 7T and a reception high-frequency coil 7R disposed in the vicinity of the subject P in the imaging space in the static magnetic field magnet 1, and transmitters connected to the high-frequency coils 7T and 7R, respectively. 8T and a receiver 8R. These transmitter 8T and receiver 8R operate under the control of the sequence controller 5 described later. By this operation, the transmitter 8T supplies an RF current pulse having a Larmor frequency for exciting nuclear magnetic resonance to the transmitting high-frequency coil 7T. The receiver 8R takes in a magnetic resonance (MR) signal (high-frequency signal) received by the receiving high-frequency coil 7R, and performs various signal processing such as preamplification, intermediate frequency conversion, phase detection, low-frequency amplification, and filtering. Then, A / D conversion is performed to generate digital data (raw data) of the MR signal.

  The control / arithmetic unit further includes a sequence controller (also called a sequencer) 5, a host computer 6, an arithmetic unit 10, a storage unit 11, a display 12, and an input device 13. Among these, the host computer 6 has a function of instructing the pulse sequence information to the sequence controller 5 according to the stored software procedure (not shown) and supervising the operation of the entire apparatus.

  The sequence controller 5 includes a CPU and a memory, stores pulse sequence information sent from the host computer 6, and controls operations of the gradient magnetic field power source 4, the transmitter 8T, and the receiver 8R according to this information. The digital data of the magnetic resonance signal output from the receiver 8R is once input and transferred to the arithmetic unit 10. Here, the pulse sequence information is all information necessary for operating the gradient magnetic field power source 4, the transmitter 8T, and the receiver 8R according to a series of pulse sequences, for example, x, y, z coils 3x to 3z. Includes information on the intensity, application time, application timing, and the like of the pulse current applied to.

  The arithmetic unit 10 inputs the digital data output from the receiver 8R through the sequence controller 5, places the digital data in the k space (also referred to as Fourier space or frequency space) of the internal memory, and stores this data. Each set is subjected to two-dimensional or three-dimensional Fourier transformation to be reconstructed into real space image data. In addition, the arithmetic unit 10 can also execute a data synthesizing process and a difference arithmetic process as necessary. This synthesis processing includes processing for adding each pixel, maximum value projection (MIP) processing, and the like.

  The storage unit 11 can store not only the reconstructed image data but also the image data that has been subjected to the above-described combining process and difference process. The display 12 is used for displaying a reconstructed image, for example. Also, parameter information desired by the surgeon, scan conditions, pulse sequences, information relating to image synthesis and difference calculation, and the like can be input to the host computer 6 via the input unit 13.

  The reception high-frequency coil 7R is actually formed by a plurality of coil elements, and magnetic resonance signals received by the coil elements are sent to the receiver 8R, respectively. The receiver 8R has four reception channels, and each reception channel is supplied with a magnetic resonance signal from a designated combination of coil elements. For this reason, digital data corresponding to the magnetic resonance signal is output from each reception channel.

  Data collected by each of the reception channels is sent to the arithmetic unit 10 via the sequence controller 5. The arithmetic unit 10 reconstructs the received collected data and generates time image data. In this reconstruction, the data collected from each coil element of the reception high-frequency coil 7R is reconstructed independently for each reception channel, and is synthesized into one image by being subjected to a square sum square root calculation. .

  Next, the configuration of the MRI apparatus related to the RF coil inspection according to the present embodiment will be described. FIG. 3 is a diagram illustrating the configuration of the MRI apparatus related to the RF coil inspection according to the present embodiment. As shown in the figure, as a configuration related to the RF coil inspection according to the present embodiment, the MRI apparatus includes a real-time system 100, a host system 200, a gradient magnetic field amplifier 310, an RF amplifier 320, a channel A331 to a channel. D 334, gradient magnetic field coil 410, RF coil 420, and gantry 430.

  The real-time system 100 is a system that controls an MRI apparatus in real time, and includes a real-time sequencer / delay controller 110, a high-frequency generator 120, an RF controller 130, and a gradient magnetic field controller 140.

  The real-time sequencer / delay controller 110 is a control device that performs sequence control, and the high-frequency generator 120 is a device that generates a high frequency applied from the RF coil 420. The RF controller 130 is a device that controls the channel A331 to channel D334 and inputs the MR signal generated in the RF coil 420, and the gradient magnetic field controller 140 is a device that controls the generation of the gradient magnetic field.

  The real-time system 100 has an imaging sequence control function and an RF coil inspection sequence control function. The imaging sequence control is sequence control when imaging a patient, and the RF coil inspection sequence control is sequence control when inspecting the RF coil 420. A pulse sequence for inspecting the RF coil 420 will be described later.

  The real-time system 100 collects MR signals input by the RF controller 130 as raw data, and transmits the collected raw data to the host system 200 via a network.

  The host system 200 is a system that receives raw data from the real-time system 100, generates reconstruction data, and generates and displays an image using the generated reconstruction data. The host system 200 corresponds to the host computer 6, the arithmetic unit 10, the storage unit 11, the display unit 12, and the input unit 13 shown in FIG.

  The host system 200 has an RF coil inspection function for inspecting the RF coil 420. That is, when the host system 200 receives the raw data collected for the inspection of the RF coil 420 from the real-time system 100, the host system 200 reconfigures the received raw data for each channel and compares it with the reference data. Inspect.

  The gradient magnetic field amplifier 310 is an amplifier that amplifies the gradient magnetic field control signal from the real-time sequencer / delay controller 110 and outputs it to the gradient magnetic field coil 410. The RF amplifier 320 is an amplifier that amplifies the high frequency generated by the high frequency generator 120 based on a signal from the real-time sequencer / delay controller 110 and outputs the amplified high frequency to the RF coil 420.

  Channel A 331 to channel D 334 are channels for the RF controller 130 to input MR signals generated in the RF coil 420. Each channel receives signals from a plurality of coil elements that constitute a high-frequency coil for reception of the RF coil 420.

  FIG. 4 is a diagram showing a combination example of coil elements when there are four coil elements. As shown in the figure, an arbitrary number of coil elements are combined to form one receiving high-frequency coil. One of the coil element combinations is assigned to each echo using a pulse sequence in one channel.

  The gradient magnetic field coil 410 is a coil that generates a gradient magnetic field, and corresponds to the gradient magnetic field coil unit 3 shown in FIG. The RF coil 420 includes a transmission high frequency coil and a reception high frequency coil, and corresponds to the transmission high frequency coil 7T and the reception high frequency coil 7R shown in FIG. That is, the receiving high-frequency coil 7R is composed of a plurality of coil elements.

  The gantry 430 includes a gradient magnetic field coil 410, an RF coil 420, and the like, and a bed and a subject are inserted therein.

  Next, a pulse sequence of the MRI apparatus according to the present embodiment will be described. FIG. 5 is an explanatory diagram for explaining a pulse sequence of the MRI apparatus according to the present embodiment. The MRI apparatus according to the present embodiment adds an RF pulse, a readout gradient magnetic field pulse, a selective excitation gradient magnetic field pulse, and a phase encoding gradient magnetic field pulse according to a pulse sequence indicating one echo (one shot) in FIG. Echo signals are collected as MR signals.

  However, when inspecting the RF coil 420, the MRI apparatus according to the present embodiment switches the coil mode and the channel assignment at the timing indicated by the mode selection in FIG. 5 without performing phase encoding. Here, the coil mode is a combination of coil elements and is also called a combination mode.

  As described above, the MRI apparatus according to the present embodiment, when inspecting the RF coil 420, uses a pulse sequence without performing phase encoding and uses a combination of coil elements and channels at the timing of mode selection for each echo. By switching the assignment, data generated by various combinations of coil elements can be efficiently collected. The mode selection timing shown in FIG. 5 may be any timing of the pulse sequence. The coil elements are combined by a signal selection circuit, and the signal selection circuit has a plurality of combination modes. If the combination of coil elements and assignment to channels can be changed for each echo using a pulse sequence, the number of imaging sequences can be one or more.

  Next, the process procedure of the inspection process of the RF coil 420 by the MRI apparatus according to the present embodiment will be described. FIG. 6 is a flowchart showing the processing procedure of the inspection processing of the RF coil 420 by the MRI apparatus according to the present embodiment.

  As shown in the figure, in this inspection process, the real-time system 100 collects data by changing the combination of coil elements and channel assignment for each echo using a pulse sequence (step S1), and the collected data is coiled. The data is transmitted to the host system 200 together with the mode (step S2).

  Then, the host system 200 compares the data of each coil mode with the reference data to identify an abnormal coil mode, that is, an abnormal coil element combination. Specifically, one piece of data is selected (step S3), and reconstructed data of complex and absolute values is created by a one-dimensional DFT (step S4). Then, the correlation between the signal intensity and the reference data is calculated (step S5), and it is determined whether or not the correlation value is smaller than a predetermined threshold value (step S6). As a result, when the correlation value is smaller than the predetermined threshold value, the coil mode corresponding to the data is determined to be abnormal (step S7), and when the correlation value is not smaller than the predetermined threshold value, it corresponds to the data. The coil mode is determined to be normal (step S8).

  Then, the host system 200 determines whether or not all data has been processed (step S9). If there is data that has not been processed, the host system 200 returns to step S3 to process the next data, When the data processing is completed, an abnormal coil element combination is displayed (step S10).

  Thus, the abnormal coil mode can be identified by comparing the correlation value of the reconfiguration data for each channel with the reference data with the predetermined threshold value. Here, since the correlation is related to the distribution of the signal intensity, the correlation value is calculated by the correlation based on the discrete correlation theorem using FFT.

  Also, here, the correlation value with the reference data is calculated, but for example, the threshold value processing is performed on the intensity distribution and the comparison with the reference data is performed. It is also possible to specify the mode. Also, an abnormal coil mode can be specified by threshold processing of raw data instead of reconstruction data. It is also possible to display raw data and reconstructed data and allow the user to select whether or not the data is normal.

  As described above, in this embodiment, when inspecting the RF coil 420, the real-time system 100 applies the phase encoding by changing the combination of coil elements and the assignment to the channel for each echo using a pulse sequence. Collect data without having to. Then, the host system 200 calculates a correlation value between the reconfigured data for each channel and the reference data, and determines that the combination of coil elements is abnormal when the correlation value is smaller than a predetermined threshold value. Therefore, it is possible to efficiently collect data for a large number of coil element combinations to determine whether or not it is normal, and the RF coil 420 can be inspected in a short time, such as during installation.

  In this embodiment, the case where data is collected without performing phase encoding has been described. However, phase encoding is performed with a smaller number than normal imaging, and 2DFFT (DFT) is performed to compare with reference data. You can also By using a plurality of phase encoding numbers, it is possible to detect anomalies with respect to more spatial spread.

  In this embodiment, the case where an echo signal is generated by applying an RF pulse has been described. However, the present invention is not limited to this, and the RF coil 420 is inspected using a pseudo signal of the echo signal. The same can be applied to the case.

  Further, in the present embodiment, the case where an abnormal coil element combination is specified has been described. However, an abnormal coil element, an abnormal channel, an abnormal signal selection circuit, and the like are specified from information on the abnormal coil element combination. You can also. For example, when there is an abnormality in data obtained from only one coil element, it can be specified that the coil element is abnormal. In addition, when data obtained from a specific channel is always abnormal, it can be specified that the channel is abnormal. Further, when there is an abnormality in data when two coil elements that are not abnormal are combined, it can be specified that there is an abnormality in the signal selection circuit that combines the two coil elements.

  In the present embodiment, the case where the abnormal coil element combination is specified has been described. However, not only the abnormal coil element combination is specified, but also the collected data is automatically corrected when the degree of abnormality is small. It can also be done. FIG. 7 is an explanatory diagram for explaining automatic correction (level correction) of collected data. As shown in the figure, the host system 200 compares the collected data collected during the RF coil inspection with the reference data, and calculates a correction value. The calculated correction value is stored in a table together with the coil element combination information, and is corrected using the correction value when data collected from the patient is reconstructed.

  Specifically, as shown in FIG. 8, a correction table 111 for storing correction values together with information on coil element combinations is provided in the storage unit 11, a correction value calculation unit 101 for calculating correction values, and data collected from a patient. A correction unit 102 that performs correction using the correction table 111 at the time of reconfiguration is provided in the arithmetic unit 10. Thus, the accuracy of the image can be improved by performing correction using the correction table 111 when the data collected from the patient is reconstructed.

  In this embodiment, the case where the abnormal coil element combination is specified has been described. However, not only the abnormal coil element combination is specified, but also an alternative for the abnormal coil element combination is automatically created. You can also FIG. 9 is an explanatory diagram for explaining automatic creation of an alternative for an abnormal coil element combination. In the same figure, for example, when there is an abnormality in one of the combinations of the coil elements in the second row, if all the coil elements in the second row are not used, the quality of the image is significantly lowered. Therefore, the host system 200 automatically creates an alternative plan in which the combination of coil elements is changed, and notifies the user of the change. In creating an alternative, not only an alternative with the same number of channels but also an alternative with a reduced number of channels is created. FIG. 9 shows a case where an alternative plan in which 5 channels are reduced to 4 channels is created.

  Further, in this embodiment, the case where the abnormal coil element combination is specified has been described. However, an imaging plan that uses the specified abnormal coil element combination is further specified, and a warning is given when the specified imaging plan is used. Can also be displayed. Alternatively, an alternative imaging plan can be found and displayed. Thus, by displaying a warning or the like at the imaging plan level instead of the coil element combination level, even a general user can cope with an abnormality in the coil element combination. The imaging plan from the abnormal coil element combination can be specified by storing the coil element combination used by the imaging plan in association with each imaging plan. Further, the search for the alternative plan can also be performed by storing the alternative plan in association with each imaging plan.

  In the present embodiment, the case where the host system 200 of the MRI apparatus receives raw data and information on the corresponding coil element combination from the real-time system 100 to identify an abnormal coil element combination has been described. However, the present invention is not limited to this, and the host system 200 sends raw data and information on the corresponding coil element combination to a remote maintenance device installed in a maintenance center or the like via a network such as a LAN or WAN. The same applies to a case where the remote maintenance device identifies an abnormal coil element combination. The remote maintenance device collects information via the network and identifies an abnormality, so that the level of maintenance service can be improved.

  In this embodiment, the case of detecting an abnormality in the coil element combination has been described. However, it is also possible to detect other abnormality using the collected data. For example, detecting spike signals in all channels of raw data, spike signals in only some channels of raw data, or detecting certain noise in the read direction of reconstructed data Thus, an abnormality such as a channel or a gradient magnetic field for reading can be specified.

  As described above, the present invention is useful for an MRI apparatus that is used as a receiving high-frequency coil by combining a plurality of coil elements, and is particularly suitable when the number of coil elements is large.

It is explanatory drawing for demonstrating use of the reconstruction data according to channel. It is a functional block diagram which shows the structure of the MRI apparatus which concerns on a present Example. It is a figure which shows the structure of the MRI apparatus relevant to the RF coil test | inspection which concerns on a present Example. It is a figure which shows the example of a coil element combination in the case of four coil elements. It is explanatory drawing for demonstrating the pulse sequence of the MRI apparatus which concerns on a present Example. It is a flowchart which shows the process sequence of the test | inspection process of RF coil by the MRI apparatus which concerns on a present Example. It is explanatory drawing for demonstrating the automatic correction | amendment of collection data. It is a figure which shows the function structure concerning the automatic correction | amendment of collection data. It is explanatory drawing for demonstrating the automatic preparation of the alternative with respect to an abnormal coil element combination.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Static magnetic field magnet 2 Static magnetic field power supply 3 Gradient magnetic field coil unit 3x x coil 3y y coil 3z z coil 4 Gradient magnetic field power supply 5 Sequence controller (sequencer)
6 Host computer 7T High-frequency coil for transmission 7R High-frequency coil for reception 8T Transmitter 8R Receiver 10 Arithmetic unit 11 Storage unit 12 Display 13 Input device 100 Real-time system 101 Correction value calculation unit 102 Correction unit 110 Real-time sequencer / delay controller 111 Correction Table 120 High-frequency generator 130 RF controller 140 Gradient magnetic field controller 200 Host system 310 Gradient magnetic field amplifier 320 RF amplifier 331 Channel A
332 Channel B
333 Channel C
334 Channel D
410 Gradient magnetic field coil 420 RF coil 430 Gantry

Claims (25)

An application unit for applying a gradient magnetic field and a high-frequency pulse to a subject placed in a static magnetic field;
A high-frequency coil having a plurality of element coils for detecting a magnetic resonance signal emitted from the subject in response to application of the gradient magnetic field and the high-frequency pulse;
A plurality of receivers for receiving and processing the magnetic resonance signals;
A signal selection circuit that synthesizes magnetic resonance signals from the plurality of element coils and inputs them to the plurality of receivers, the signal selection circuit having a plurality of combination modes of combining the magnetic resonance signals;
An imaging sequence controller for switching a plurality of combination modes during execution of one or a plurality of imaging sequences and collecting magnetic resonance signals for each of the combination modes;
An abnormality specifying unit that specifies an abnormality of at least one of the combination mode, the element coil, the receiver, and the combiner for combining based on the magnetic resonance signals of the plurality of combined modes. Magnetic resonance imaging apparatus. When an abnormality of the combination mode is specified by the abnormality specifying unit, a correction value calculation unit that calculates a correction value of the magnetic resonance signal for the combination mode in which the abnormality is specified;
The magnetic resonance imaging according to claim 1, further comprising: a correction unit that corrects a magnetic resonance signal detected by the high-frequency coil based on the correction value calculated by the correction value calculation unit. apparatus. The correction value calculation unit stores the calculated correction value together with the combination mode in the correction value storage unit,
The magnetic resonance imaging apparatus according to claim 2, wherein the correction unit reads a correction value from the correction value storage unit and corrects a magnetic resonance signal detected by the high-frequency coil. 2. The magnetic resonance according to claim 1, further comprising: an alternative mode creation unit that creates a combination mode that substitutes a combination mode in which an abnormality is specified by the abnormality specifying unit, including a case where the number of channels is reduced. Imaging device. 3. The magnetic resonance according to claim 2, further comprising: an alternative mode creation unit that creates a combination mode that substitutes a combination mode in which an abnormality is specified by the abnormality specifying unit, including a case where the number of channels is reduced. Imaging device.   The abnormality identifying unit reconstructs the magnetic resonance signals collected by switching the combination mode by the imaging sequence control unit for each channel, and compares the magnetic resonance signals reconstructed for each channel with a reference. The magnetic resonance imaging apparatus according to claim 1, wherein a combination mode is specified.   The abnormality identifying unit reconstructs the magnetic resonance signals collected by switching the combination mode by the imaging sequence control unit for each channel, and compares the magnetic resonance signals reconstructed for each channel with a reference. The magnetic resonance imaging apparatus according to claim 2, wherein a combination mode is specified.   The abnormality identifying unit reconstructs the magnetic resonance signals collected by switching the combination mode by the imaging sequence control unit for each channel, and compares the magnetic resonance signals reconstructed for each channel with a reference. The magnetic resonance imaging apparatus according to claim 4, wherein a combination mode is specified.   The abnormality identifying unit reconstructs the magnetic resonance signals collected by switching the combination mode by the imaging sequence control unit for each channel, and compares the magnetic resonance signals reconstructed for each channel with a reference. 6. The magnetic resonance imaging apparatus according to claim 5, wherein a combination mode is specified. A simulation signal generator for generating a simulation signal for simulating the magnetic resonance signal;
The abnormality specifying unit collects a magnetic resonance signal that specifies at least one of a combination mode, an element coil, a receiver, and a combiner for combining based on the simulated signal generated by the simulated signal generating unit. The magnetic resonance imaging apparatus according to claim 1. A simulation signal generator for generating a simulation signal for simulating the magnetic resonance signal;
The abnormality specifying unit collects a magnetic resonance signal that specifies at least one of a combination mode, an element coil, a receiver, and a combiner for combining based on the simulated signal generated by the simulated signal generating unit. The magnetic resonance imaging apparatus according to claim 2. A simulation signal generator for generating a simulation signal for simulating the magnetic resonance signal;
The abnormality specifying unit collects a magnetic resonance signal that specifies at least one of a combination mode, an element coil, a receiver, and a combiner for combining based on the simulated signal generated by the simulated signal generating unit. The magnetic resonance imaging apparatus according to claim 4. A simulation signal generator for generating a simulation signal for simulating the magnetic resonance signal;
The abnormality specifying unit collects a magnetic resonance signal that specifies at least one of a combination mode, an element coil, a receiver, and a combiner for combining based on the simulated signal generated by the simulated signal generating unit. The magnetic resonance imaging apparatus according to claim 5. A simulation signal generator for generating a simulation signal for simulating the magnetic resonance signal;
The abnormality specifying unit collects a magnetic resonance signal that specifies at least one of a combination mode, an element coil, a receiver, and a combiner for combining based on the simulated signal generated by the simulated signal generating unit. The magnetic resonance imaging apparatus according to claim 6. A simulation signal generator for generating a simulation signal for simulating the magnetic resonance signal;
The abnormality specifying unit collects a magnetic resonance signal that specifies at least one of a combination mode, an element coil, a receiver, and a combiner for combining based on the simulated signal generated by the simulated signal generating unit. The magnetic resonance imaging apparatus according to claim 7. A simulation signal generator for generating a simulation signal for simulating the magnetic resonance signal;
The abnormality specifying unit collects a magnetic resonance signal that specifies at least one of a combination mode, an element coil, a receiver, and a combiner for combining based on the simulated signal generated by the simulated signal generating unit. The magnetic resonance imaging apparatus according to claim 8. An abnormal imaging plan identifying unit that identifies an imaging plan that uses the abnormal combination mode identified by the abnormality identifying unit;
The magnetic resonance imaging apparatus according to claim 1, further comprising: a warning output unit that outputs a warning about the imaging plan specified by the abnormal imaging plan specifying unit. An abnormal imaging plan identifying unit that identifies an imaging plan that uses the abnormal combination mode identified by the abnormality identifying unit;
The magnetic resonance imaging apparatus according to claim 2, further comprising: a warning output unit that outputs a warning for the imaging plan specified by the abnormal imaging plan specifying unit. An abnormal imaging plan identifying unit that identifies an imaging plan that uses the abnormal combination mode identified by the abnormality identifying unit;
The magnetic resonance imaging apparatus according to claim 4, further comprising: a warning output unit that outputs a warning about the imaging plan specified by the abnormal imaging plan specifying unit. An abnormal imaging plan identifying unit that identifies an imaging plan that uses the abnormal combination mode identified by the abnormality identifying unit;
The magnetic resonance imaging apparatus according to claim 6, further comprising: a warning output unit that outputs a warning for the imaging plan specified by the abnormal imaging plan specifying unit. An abnormal imaging plan identifying unit that identifies an imaging plan that uses the abnormal combination mode identified by the abnormality identifying unit;
The magnetic resonance imaging apparatus according to claim 9, further comprising: a warning output unit that outputs a warning about the imaging plan specified by the abnormal imaging plan specifying unit.   The magnetic resonance imaging apparatus according to claim 17, further comprising: an alternative plan generation unit that generates an alternative plan for the imaging plan for which the warning is output by the warning output unit. Magnetic resonance signals for each combination mode collected by a magnetic resonance imaging apparatus having a plurality of combined combination modes for combining magnetic resonance signals detected by a plurality of element coils while switching between a plurality of combination modes during execution of one imaging sequence. An acquisition unit to acquire;
Based on the magnetic resonance signal for each combination mode acquired by the acquisition unit, an abnormality specifying unit that specifies an abnormality of at least one of the combination mode, the element coil, the receiver, and the combiner for combining Magnetic resonance imaging maintenance apparatus characterized by the above. An application unit for applying a gradient magnetic field and a high-frequency pulse to a subject placed in a static magnetic field;
A high-frequency coil having a plurality of element coils for detecting a magnetic resonance signal emitted from the subject in response to application of the gradient magnetic field and the high-frequency pulse;
A plurality of receivers for receiving and processing the magnetic resonance signals;
A signal selection circuit that synthesizes magnetic resonance signals from the plurality of element coils and inputs them to the plurality of receivers, the signal selection circuit having a plurality of combination modes of combining the magnetic resonance signals;
A magnetic resonance imaging apparatus comprising: an imaging sequence control unit configured to switch a plurality of combination modes during execution of one or a plurality of imaging sequences and collect a magnetic resonance signal for each combination mode;
The magnetic resonance imaging apparatus acquires a magnetic resonance signal for each combination mode acquired by switching a plurality of combination modes; and
Based on the magnetic resonance signal for each combination mode acquired by the acquisition unit, an abnormality specifying unit that specifies an abnormality of at least one of the combination mode, the element coil, the receiver, and the combiner for combining A magnetic resonance imaging maintenance system comprising: a magnetic resonance imaging maintenance device. A magnetic resonance imaging method using a magnetic resonance imaging apparatus having a plurality of combined combination modes for combining magnetic resonance signals detected by a plurality of element coils,
A collection step of switching a plurality of combination modes during execution of one or a plurality of imaging sequences and collecting a magnetic resonance signal for each combination mode;
An abnormality specifying step for specifying an abnormality in at least one of the combination mode, the element coil, the receiver, and the combiner for combining based on the magnetic resonance signals of the plurality of combined modes acquired in the acquiring step. A magnetic resonance imaging method characterized by that.

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