JP5421600B2 - Nuclear magnetic resonance imaging apparatus and method of operating nuclear magnetic resonance imaging apparatus - Google Patents

Description

  The present invention relates to a nuclear magnetic resonance imaging (MRI) apparatus that corrects the sensitivity of an RF receiving coil, and more particularly to a nuclear magnetic resonance imaging apparatus that reduces the influence of misalignment during sensitivity measurement.

  The MRI device measures NMR signals generated by the spins of the subject, especially the tissues of the human body, and visualizes the form and function of the head, abdomen, limbs, etc. in two or three dimensions Device. In imaging, the NMR signal is given different phase encoding and frequency encoding depending on the gradient magnetic field. The measured NMR signal is reconstructed into an image by two-dimensional or three-dimensional Fourier transform.

Hereinafter, the outline of the prior art for the present invention will be described with reference to literature.
An NMR signal generated from the subject is measured using an RF receiving coil. The smaller the diameter of the RF receiving coil, the narrower the sensitivity distribution, but the SNR (Signal to Noise Ratio) improves. Therefore, wide sensitivity distribution and high SNR are realized by using multiple coils that combine multiple small-diameter RF receiving coils. However, multiple coils often support parallel imaging. Since parallel imaging is a technique for speeding up imaging using a sensitivity distribution of multiple coils, each reception channel is arranged so that the sensitivity distribution becomes independent. For this reason, non-uniform sensitivity is likely to occur in image signals measured by multiple coils, and sensitivity correction is necessary.

  One of the sensitivity correction techniques is whole body coil type sensitivity correction. The whole body coil type sensitivity correction performs sensitivity measurement different from the main measurement for the whole body coil (body coil, transmission / reception coil) with uniform sensitivity distribution and multiple coils, and calculates the correction coefficient from them to calculate the main measurement image. This is a technique for correcting (Patent Document 1). At this time, a position shift may occur between the whole body coil sensitivity measurement and the multiple coil sensitivity measurement due to the movement of the subject such as respiratory motion or heartbeat. In addition, a positional deviation may occur between the sensitivity measurement and the main measurement. Such misalignment decreases sensitivity correction accuracy in any case. Further, in the case of parallel imaging including sensitivity correction of multiple coils, the above-described misalignment causes not only a reduction in sensitivity correction accuracy but also a folding expansion error.

  In order to avoid such a deterioration in image quality, a method has been proposed in which the positional deviations are averaged by adding sensitivity measurements a plurality of times (Non-Patent Document 1).

  In addition, when performing the main measurement synchronized with the movement of the subject, such as respiratory synchronization and electrocardiogram synchronization, synchronization is also performed during sensitivity measurement in the same way as the main measurement, and only sensitivity measurement data that matches the time phase of the main measurement is obtained. A method of using as a sensitivity image for parallel imaging including sensitivity correction or sensitivity correction has been proposed (Patent Document 2).

  In this measurement, as a method of imaging the thoracoabdominal region without holding the breath, observation is performed while measuring the relationship between the respiratory displacement (diaphragm displacement) and the number of data points, and the gate is automatically gated to the location with the best data collection efficiency. PAWS in which a window is set has been proposed (Non-Patent Document 2).

JP-A-8-56928 Japanese Patent Laid-Open No. 2002-301044

“Cardiac real-time imaging using SENSE”, MRM, 43, 177-184 (2000) “Phase Ordering With Automatic Window Selection (PAWS): A Novel Motion-Resistant Technique for 3D Coronary Imaging”, MRM, 43, 470-480 (2000)

  An object of the present invention is to prevent a decrease in sensitivity correction accuracy due to a displacement of a subject during sensitivity measurement. In Non-Patent Document 1, since the sensitivity measurement is added multiple times, the measurement time is greatly extended, and the position due to body movement of the subject being measured may cause a decrease in sensitivity correction accuracy. It is. In addition, the use of Non-Patent Document 2 for sensitivity measurement has the problems that the processing is complicated because the respiratory displacement is detected in parallel with the measurement, and that the time required for measurement depends on the stability of the breath. is there. In the present invention, a sensitivity image is obtained in which the influence of positional deviation between sensitivity measurements is reduced without extending the measurement time and without performing complicated internal processing as in PAWS.

The nuclear magnetic resonance imaging apparatus of the present invention includes an RF receiving coil, a whole body coil having a substantially uniform sensitivity distribution, a signal processing means for obtaining an MR image from the NMR signal received by the RF receiving coil and the whole body coil, A control means for controlling the magnetic field acting on the examination region of the subject and controlling the processing of the NMR signal, and the RF receiving coil or the whole body coil from signals measured using the RF receiving coil and the whole body coil In the nuclear magnetic resonance imaging apparatus that creates an MR image of the subject, measures an NMR signal of the subject with the RF receiving coil, and creates an MR image using the NMR signal of the subject and the sensitivity image. The means includes the RF receiver coil or the whole body code from the signal measured using the RF receiver coil or the whole body coil. As a configuration for creating a sensitivity image of a subject, a monitoring unit that monitors the periodic movement of the subject, a dividing unit that divides the movement of the subject into a plurality of regions, and a K space that is divided into a plurality of regions A K space dividing unit; an encoding order determining unit that determines the order of phase encoding and slice encoding in each region in the K space; an associating unit that associates each movement of the subject with each region in the K space; possess an encode amount determining section for determining a phase encode and slice encode amounts in accordance with the movement, and a scan control unit for controlling the gradient magnetic field in accordance with the phase encoding and slice encoding amount of the determined, of the subject dividing unit for dividing the motion into a plurality of regions, to characterized in that the data points are divided into a plurality of regions to be the same in each of divided areas It is intended.

In addition, the operation method of the nuclear magnetic resonance imaging apparatus of the present invention obtains an MR image from an RF receiving coil, a whole body coil having a substantially uniform sensitivity distribution, and an NMR signal received by the RF receiving coil and the whole body coil. In a nuclear magnetic resonance imaging apparatus comprising a signal processing unit and a control unit that controls a magnetic field acting on an examination region of a subject and controls the processing of the NMR signal, measurement is performed using the RF receiving coil and the whole body coil A sensitivity image creating step of creating a sensitivity image of the RF receiving coil or the whole body coil from the obtained signal, a main measuring step of measuring the NMR signal of the subject with the RF receiving coil, the NMR signal of the subject and the sensitivity And an image creation step of creating an MR image using the image. A sensitivity image creating step of creating a sensitivity image of the RF receiving coil or the whole body coil from a signal measured using the RF receiving coil and the whole body coil includes a step of monitoring a periodic movement of the subject; Dividing the movement of the specimen into a plurality of areas; dividing the K space into a plurality of areas; determining the order of phase encoding and slice encoding in each area of the K space; Associating each region of the K space; determining a phase encoding and slice encoding amount according to the movement of the subject; obtaining an echo signal according to the determined phase encoding and slice encoding amount; have a placing in the K space according to the obtained echo signals to the motion of the subject Wherein said step of dividing the movement of the object into a plurality of regions, and is characterized in that the number of data points in each divided areas is divided into a plurality of regions to be the same.

  By performing sensitivity measurement according to the present invention, it is possible to acquire a sensitivity image with reduced positional deviation between sensitivity measurements without extending the measurement time. Accordingly, it is possible to prevent a decrease in sensitivity correction accuracy due to a periodic movement of the subject such as respiratory motion or heartbeat.

The figure showing the processing flow of Example 1 of this invention. The figure showing the whole structure of the MRI apparatus with which this invention is applied. The figure showing the internal structure of the sequencer of this invention The figure which showed how to represent the position in K space in this invention. A diagram showing an example of the relationship between encoding amount and K space FIG. 3 is a diagram for explaining an example of K space scanning in the first embodiment. FIG. 3 is a diagram for explaining an example of K space scanning in the first embodiment. The figure explaining the other example of the K space division | segmentation method. FIG. 10 is a diagram illustrating a processing flow of a modification of the respiratory displacement dividing method according to the first embodiment. FIG. 6 is a diagram illustrating a modification of the respiratory displacement dividing method according to the first embodiment. FIG. 6 is a diagram illustrating a modification of the respiratory displacement dividing method according to the first embodiment. FIG. 6 is a diagram illustrating a processing flow of the second embodiment. FIG. 6 is a diagram for explaining a method for monitoring respiratory displacement in the second embodiment. FIG. 6 is a diagram for explaining an example of K space scanning in the second embodiment. FIG. 6 is a diagram illustrating a respiratory displacement dividing method according to the third 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 configuration of an example of an MRI apparatus to which the present invention is applied 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 obtains a tomographic image of a subject using the NMR phenomenon. 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 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, and 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 into an echo signal.
The sequencer 4 is a control means 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. 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.
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. 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 the timing according to the 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.
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, an internal storage device including a ROM 21, a RAM 22, and the like, a CRT, and the like. When the data from the receiving system 6 is input to the CPU 8, the CPU 8 executes processing such as signal processing and image reconstruction, and the resulting tomographic image of the subject 1 is displayed on the display 20. The information is displayed and recorded on the magnetic disk 18 of the external storage device.
The operation unit 25 inputs various control information of the MRI apparatus and control information of processing performed in 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.
The high-frequency coil 14a and the gradient magnetic field coil 9 on the transmission side are placed in a static magnetic field space of the static magnetic field generation system 2 in which the subject 1 is inserted, and face the subject 1 in the case of the vertical magnetic field method. In the case of the method, it is installed so as to surround the subject 1. 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) which is a main constituent material of the subject as widely used in clinical practice. By imaging information on the spatial distribution of proton density and the spatial distribution of relaxation time in the excited state, the form or function of the human head, abdomen, limbs, etc. is imaged two-dimensionally or three-dimensionally.

  The sensitivity correction in the present invention is performed as follows, for example. First, the sensitivity distribution of the RF receiving coil and the whole body coil is measured, and a sensitivity image (correction value) is created from the sensitivity distribution of the RF receiving coil and the sensitivity distribution of the whole body coil. Next, the main measurement of the subject is performed using the RF receiver coil, and the image reconstructed using the signal obtained by correcting the signal measured in the main measurement with the sensitivity image (correction value), and the MRI image of the subject. Get.

Next, examples of the present invention will be described below. The present embodiment is used for measuring sensitivity of a whole body coil or measuring sensitivity of an RF receiving coil.
The following examples all monitor the respiratory displacement of the subject. However, the present invention can be applied to any device that monitors the periodic movement of the subject, for example, monitoring of heart beats. It can be applied to what you do.

  First, the first embodiment will be described. FIG. 1 is a diagram showing a processing flow of the first embodiment of the present invention, and FIG. 3 is a diagram showing an internal configuration of the sequencer. In this embodiment, first, sensitivity measurement parameters are set (step 201). The sequence used for sensitivity measurement is preferably 3D measurement. The sensitivity measurement range (FOV) must be set to cover the range of this measurement. The measurement parameter is desirably set so as to obtain a proton density weighted image or a contrast equivalent thereto. The number of echoes to be acquired is set from the movement characteristics (speed, direction, etc.) of the imaging region and TR (repetition time). In the present invention, it is not necessary to consider the photographing conditions of the main measurement at the time of sensitivity measurement. Therefore, the sensitivity measurement can be performed without being aware of the photographing time phase of the main measurement. For this reason, the sensitivity measurement according to the present invention may be performed once after the subject is set, and it is not necessary to re-measure during the examination.

  In the first embodiment, the respiratory displacement of the subject is monitored using the respiratory sensor 26 (step 202). Subsequently, the processing from step 203 to step 206 is performed based on the parameters set in step 201. That is, the respiratory displacement is divided into M according to the number of parameters set (step 203), the K space is divided into M according to the parameter setting method and the number (step 204), and each region of the K space The order of phase encoding and slice encoding is determined (step 205), and the respiratory displacement is associated with each region of the K space (step 206). Further, a phase encoding amount (Gy) and a slice encoding amount (Gz) are determined according to the respiratory displacement (step 207), and an echo signal is acquired (step 208). In the first embodiment, for the sake of simplicity, a case will be described in which the respiratory displacement is equally divided into four regions 1 to 4 parallel to the time axis as shown in FIG. The size of the area before dividing must include the total respiratory displacement, and the size is determined automatically. For example, when the displacement is in the region 1, the encoding amount is determined so that Gy ≧ 0 and Gz ≧ 0, and an echo signal is acquired. Since the positions in Gy, Gz, and K space correspond one-to-one, the position in K space corresponding to Gy is Ky, and the position in K space corresponding to Gz is Kz. When expressed, the position in the K space can be expressed by the following (formula 1). FIG. 5 shows the relationship between the encoding amount and the K space using an example of a gradient echo system. In this example, the echo signal fills the K space like 501.

The acquired echo signal is arranged in the K space according to the respiratory displacement as shown in FIG. 6 (step 209). Here, FIG. 7 shows an example of K space scanning. For example, assuming a Matrix of m × m (m> 0) , the number of data necessary for the region 1 of the K-space is m ^2/4 pieces, for one slice encode amount, m / 2 pieces The amount of phase encoding is required. In the first embodiment, as shown in FIG. 7A, an echo signal obtained by adding m / 2 phase encoding amounts to one slice encoding amount is acquired, and then the processing proceeds to the next slice encoding amount. . The K space scanning is 1⇒2⇒3⇒ ... as shown in FIG. Similarly, for the areas 2 to 4, data is sequentially acquired from the center of the K space in the Ky axis direction. In the first embodiment, K space scanning is performed as shown in FIG. 7, but data may be acquired sequentially in the Kz direction from the center of the K space, or data may be acquired at random. Further, the K space may be divided so as to create an overlap region as shown in FIG. 8A, or may be divided concentrically as shown in FIG. 8B. Finally, after applying a filter (step 210), a sensitivity image is obtained by performing an inverse Fourier transform (step 211). The measurement processing from step 201 to step 206 is performed for the whole body coil and the multiple coil. However, the setting part in step 201 may be used in common for the whole body coil and the multiple coil, and the measurement processing from step 202 to step 211 may be performed for each of the whole body coil and the multiple coil.

  By arranging the echo signal in the K space according to the respiratory displacement in this way, it is possible to expect to obtain a sensitivity image with reduced influence of body movement as a result. That is, by collecting various respiratory displacement data in the low frequency region of the K space that determines the overall image, an image averaged with respect to the respiratory displacement can be obtained, and as a result, high resolution is not required. The sensitivity image can reduce the influence of body movement.

  FIG. 3 is a diagram showing an internal configuration of the sequencer in the present embodiment. In FIG. 3, 31 is a parameter setting unit that sets parameters for sensitivity measurement based on information input from the operation unit 25, for example, and 32 is a respiratory displacement monitoring unit that monitors the respiratory displacement of the subject. 33 is a respiratory displacement dividing unit that divides the respiratory displacement according to the number set by the parameter setting unit, and 34 is a K space that divides the K space according to the division method and the number set by the parameter setting unit. The dividing unit 35 is an encoding order determining unit that determines the order of phase encoding and slice encoding in each region of the K space, and 36 is each region of the divided respiratory displacement and each region of the K space that is divided. , 37 is an encoding amount determination unit that determines the amount of phase encoding and slice encoding according to the displacement, and 38 is For example, the scan control unit performs control so as to apply a gradient magnetic field in accordance with the determined encoding amount. These are usually composed of programs for operating the sequencer.

  In the first embodiment, the case where the respiratory displacement is equally divided into four has been described, but the respiratory displacement is generally equally divided into M (M> 0) as in the processing flow of the present invention in FIG. According to this, the K space is also divided into M pieces, and the obtained echo signals are arranged in the K space accordingly. It is assumed that the user can set the respiratory displacement division method, the division number M, and the overlap area (θ of each area dividing the K space) from the UI.

Up to this point, the case where the respiratory displacement is divided equally has been described. However, the respiratory displacement may be divided so that the number of data points (density) is the same in each divided region. That is, there is a modification of step 203 of the present invention flow in FIG. 1, and the method will be described below with reference to FIGS.
First, sensitivity measurement parameters are set (step 301), and respiratory displacement is monitored by using a respiration sensor (step 302), while measuring at least one respiratory cycle in the sensitivity measurement sequence, and breathing is performed as shown in FIG. The number of data points for one cycle is grasped (step 303). Once the number of data points is known, the number of data points in the area to be divided is set to the same number. The method will be described later. Here, for the sake of simplicity, a case where the respiratory displacement is divided into four will be described, but in general, it may be divided into M (M> 0).
The number of data points (density) of the divided areas is set to the same number as follows. First, as shown in FIG. 10, the respiratory displacement is equally divided into four, and a histogram is created using the number of data points in each region (step 304). From the histogram, displacement coordinates are stored such that the number of data points in each region is equal as shown in FIG. 11 (step 305). Further, the respiratory displacement is automatically subdivided into four based on the stored displacement coordinates (step 306), so that the number of data points (density) in each region is approximately equal.
In general, N (N> 0) may be sufficient as the number of breathing cycles for grasping the number of data points, and the accuracy increases when N is large. The user sets the number M of respiratory displacement divisions and the number N of respiratory cycles for grasping the number of data points from the UI.
The number of data points (density) in each region is made equal in this way, and the processing from step 307 to step 314 is performed in the same manner as step 204 to step 211 in the processing flow of the first embodiment.

As a second embodiment, a case where the respiratory displacement of a subject is monitored using navigator echo will be described. In other words, there is a variation in the (step 202) of the present invention flow of FIG. 1, and the method will be described below with reference to FIGS. As an example, consider an image of the abdomen AX cross section of exhaled air and inspired as shown in FIG. When the navigator echo is used and the data obtained without applying phase encoding (RL) is subjected to inverse Fourier transform in the readout direction (AP), a projection is obtained as shown in FIG. Respiration displacement is monitored using this projection. The correlation between the projection length and the respiration needs to be grasped before the sensitivity image measurement, and the positioning image is acquired and stored in a sequence to which the navigator echo is added (step 401). Subsequently, after setting sensitivity measurement parameters (step 402), the processing from step 403 to step 407 is performed using the correlation between the projection length and respiration. It is considered that the correlation between the length of projection and respiration is as shown in FIG. The sensitivity measurement is performed by adding a navigation pulse between the sensitivity measurement sequences as shown in FIG. 13 (c), and the phase encoding amount and the slice encoding amount are determined based on the information obtained by the projection (step 408), and the echo is performed. A signal is acquired (step 409). Furthermore, echo signals are arranged in the K space as shown in FIG. 14 according to the projection length (step 410), and a sensitivity image is obtained by performing inverse Fourier transform (step 412). However, the method for determining the phase encoding amount and the slice encoding amount is the same as the processing in FIG. 1 (step 207) of the first embodiment. The purpose of arranging the echo signal in the K space according to the projection length is the same as in the first embodiment. For simplicity, consider the case where the projection length is divided into four areas, as shown in FIG. 14, but the projection length may generally be divided into M (M> 0) areas. . Further, the area may be divided by dividing the projection length into equal parts, or may be divided so that the number of data points (density) in each area is the same. When dividing so that the number of data points (density) in each region is equal, create a histogram of the number of data points for at least one respiratory cycle with reference to Example 1, and the number of data points (density) in each region is equal. Divide by such projection length. The number of breathing cycles N and the number of divisions M can be set by the user from the UI.
In the second embodiment, the method of using the projection length only in the AP direction has been described. However, projections in all three axes of AP, RL, and HF may be used.

  As a third embodiment, a method for dividing the respiratory displacement perpendicular to the time axis will be described. As a method of dividing the respiratory displacement, the respiratory displacement may be divided perpendicularly to the time axis as shown in FIG. Also for this division method, it is possible to acquire the echo signal according to the respiratory displacement or the length of the projection as in the first and second embodiments, and to arrange the echo signal in the K space.

  The present invention can be used in a magnetic resonance imaging apparatus adapted to perform sensitivity correction of an RF receiving coil.

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 supply, 11 ... High frequency transmitter, 12 ... Modulator, 13 ... High frequency Amplifier, 14a ... high frequency coil (transmitting coil), 14b ... high frequency coil (receiving coil), 15 ... signal amplifier, 16 ... quadrature phase detector, 17 ... A / D converter, 18 ... Magnetic disk, 19 ... Optical disk, 20 ... Display, 21 ... ROM, 22 ... RAM, 23 ... Trackball or mouse, 24 ... Keyboard, 25 ... Operation unit, 26 ... respiration sensor, 31 ... parameter setting unit, 32 ... respiration displacement monitoring unit, 33 ... respiration displacement division unit, 34 ... K space division unit, 35 ... Nkodo order determination unit, 36 ... mapping unit, 37 ... encoding quantity determining unit, 38 ... scan control unit.

Claims (15)

An RF receiver coil, a whole body coil having a substantially uniform sensitivity distribution, a signal processing means for obtaining an MR image from NMR signals received by the RF receiver coil and the whole body coil, and a magnetic field acting on the examination region of the subject. And a control means for controlling the processing of the NMR signal, and creating a sensitivity image of the RF receiving coil or the whole body coil from signals measured using the RF receiving coil and the whole body coil, and the RF In a nuclear magnetic resonance imaging apparatus that measures an NMR signal of a subject with a receiving coil and creates an MR image using the NMR signal of the subject and the sensitivity image,
The control means, as a configuration for creating a sensitivity image of the RF receiving coil or the whole body coil from a signal measured using the RF receiving coil or the whole body coil,
A monitoring unit for monitoring the periodic movement of the subject;
A dividing unit for dividing the movement of the subject into a plurality of regions;
A K space dividing unit for dividing the K space into a plurality of regions;
An encoding order determining unit that determines the order of phase encoding and slice encoding in each region in the K space;
An associating unit for associating the movement of the subject with each region of the K space;
An encoding amount determination unit that determines a phase encoding and a slice encoding amount according to the movement of the subject;
Have a scan control unit for controlling the gradient magnetic field in accordance with the phase encoding and slice encoding amount of the determined,
A nuclear magnetic resonance imaging apparatus, wherein the dividing unit that divides the movement of the subject into a plurality of regions divides the movement into a plurality of regions so that the number of data points is the same in each divided region . The nuclear magnetic resonance imaging apparatus according to claim 1.
The RF receiver coils, nuclear magnetic resonance imaging apparatus you being a multiple coil combining a plurality of small diameter RF receiver coil. The nuclear magnetic resonance imaging apparatus according to claim 1 or 2,
The periodic movement of the subject is respiratory displacement or heartbeat displacement, the monitoring unit monitors the respiratory displacement or heartbeat displacement of the subject, and a dividing unit that divides the movement of the subject into a plurality of regions. , nuclear magnetic resonance imaging apparatus shall be the dividing means divides the breathing displacement or heart displaced into a plurality of regions. In the nuclear magnetic resonance imaging apparatus according to any one of claims 1 to 3,
The control means further includes a parameter setting unit for setting sensitivity measurement parameters, and the dividing unit divides the movement of the subject into a plurality of regions according to the number set by the parameter setting unit, and the K space division unit, division methods set by the parameter setting unit, nuclear magnetic resonance imaging apparatus you characterized in that for dividing the K space into a plurality of areas according to the number. In the nuclear magnetic resonance imaging apparatus according to any one of claims 1 to 4,
The division unit that divides the movement of the subject into a plurality of regions divides the movement of the subject in parallel to the time axis, or divides the movement of the subject perpendicular to the time axis. nuclear magnetic resonance imaging apparatus shall be the features. The nuclear magnetic resonance imaging apparatus according to claim 3.
Monitoring of a subject breathing displacement, nuclear magnetic resonance imaging apparatus you and performing with respiratory sensor or navigator echo. The nuclear magnetic resonance imaging apparatus according to any one of claims 1 to 6,
  The nuclear magnetic resonance imaging apparatus, wherein the K space dividing unit divides the K space so that various respiratory displacement data are collected in a low frequency region of the K space. The nuclear magnetic resonance imaging apparatus according to any one of claims 1 to 6,
  The nuclear magnetic resonance imaging apparatus, wherein the K space dividing unit divides the K space in parallel to the K space coordinate axis, radially through the K space origin, or concentrically. The nuclear magnetic resonance imaging apparatus according to any one of claims 1 to 6,
  The nuclear magnetic resonance imaging apparatus, wherein the K space dividing unit divides the K space so that a part of the divided regions overlap. An RF receiving coil, a whole body coil having a substantially uniform sensitivity distribution, a signal processing unit for obtaining an MR image from the NMR signal received by the RF receiving coil and the whole body coil, and a magnetic field acting on the examination region of the subject. In a nuclear magnetic resonance imaging apparatus comprising a control and a control unit for controlling the processing of the NMR signal, a sensitivity image of the RF receiving coil or the whole body coil is obtained from a signal measured using the RF receiving coil and the whole body coil. A sensitivity image creation step for creating, a main measurement step for measuring the NMR signal of the subject with the RF receiving coil, and an image creation step for creating an MR image using the NMR signal of the subject and the sensitivity image. A method of operating a nuclear magnetic resonance imaging apparatus comprising:
A sensitivity image creating step of creating a sensitivity image of the RF receiving coil or the whole body coil from a signal measured using the RF receiving coil and the whole body coil,
Monitoring the periodic movement of the subject;
Dividing the movement of the subject into a plurality of regions;
Dividing the K space into a plurality of regions;
Determining the order of phase encoding and slice encoding in each region of K-space;
Associating the movement of the subject with each area of the K space;
Determining a phase encoding and a slice encoding amount according to the movement of the subject;
Obtaining an echo signal in accordance with the determined phase encoding and slice encoding amounts;
Have a placing in the K space according to the obtained echo signals to the motion of the object,
A method of operating a nuclear magnetic resonance imaging apparatus, wherein the step of dividing the movement of the subject into a plurality of regions is divided into a plurality of regions so that the number of data points is the same in each divided region . The operation method of the nuclear magnetic resonance imaging apparatus according to claim 10,
The RF receiving coil, method for operating a nuclear magnetic resonance imaging apparatus you being a multiple coil combining a plurality of small diameter RF receiver coil. The operation method of the nuclear magnetic resonance imaging apparatus according to claim 10 or 11,
Wherein said step of monitoring the periodic motion of the subject method for operating a nuclear magnetic resonance imaging apparatus you characterized in that to monitor the breathing displacement or heart displacement. The operation method of the nuclear magnetic resonance imaging apparatus according to any one of claims 10 to 12,
The sensitivity measurement step further includes a step of setting a sensitivity measurement parameter, and the step of dividing the movement of the subject into a plurality of regions is a plurality according to the number set in the step of setting the sensitivity measurement parameter. The step of dividing the K space into a plurality of regions is the division method set in the step of setting the sensitivity measurement parameter, and the K space is divided into a plurality of regions according to the number method for operating a nuclear magnetic resonance imaging apparatus you wherein a is. The operation method of the nuclear magnetic resonance imaging apparatus according to any one of claims 10 to 13,
The step of dividing the movement of the subject into a plurality of regions is to divide the movement of the subject in parallel to the time axis, or to divide the movement of the subject perpendicular to the time axis. method for operating a nuclear magnetic resonance imaging apparatus shall be the. The method of operating a nuclear magnetic resonance imaging apparatus according to claim 12,
Method of operating a monitoring of a subject breathing displacement, breathing sensor, or nuclear magnetic resonance imaging apparatus you and performing using navigator echoes.

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