JP4912808B2 - Magnetic resonance imaging system - Google Patents

Description

  The present invention relates to a magnetic resonance imaging (MRI) apparatus, in particular, based on a magnetic resonance signal generated in a subject by irradiating the subject with an RF pulse in a static magnetic field space. The present invention relates to a magnetic resonance imaging apparatus for generating an image.

  Magnetic resonance imaging apparatuses are used in various fields such as medical applications and industrial applications.

  The magnetic resonance imaging apparatus irradiates a subject in a static magnetic field space with an RF pulse, thereby exciting the spin of protons in the subject by a nuclear magnetic resonance (NMR) phenomenon. A scan is performed to obtain a magnetic resonance (MR) signal generated by the spin. Then, a slice image of the subject is generated by using the magnetic resonance signal obtained by the scan as raw data (raw data) of the slice image (see, for example, Patent Document 1).

  When scanning a subject using a magnetic resonance imaging apparatus in this way, if body movement occurs in the subject, the cross section that should be excited and the cross section that is actually excited will be misaligned. Body motion artifacts may occur in the slice image generated in the generated image.

  Thus, several methods for solving the problem of body movement have been proposed. One of the methods is, for example, in cardiac imaging under normal breathing, the excitation cross section of the subject is corrected in real time according to the change in the position of the diaphragm, and the magnetic resonance signal is always measured from the same cross section (patent) Reference 2). As a technique for detecting the position of the diaphragm used in these technologies, a sequence (navigator sequence) for measuring a magnetic resonance signal without applying phase encoding from the diaphragm is performed separately from the original image sequence, and the obtained magnetic resonance signal (navigator sequence). A method for detecting the position of the diaphragm from the projection of the echo) has been proposed.

  In this method, the application position of the navigator sequence is, for example, a linear region where two cross sections in a direction substantially perpendicular to the diaphragm intersect, and a magnetic resonance signal with zero phase encoding is acquired from this linear region. That is, 90 ° excitation is performed on the first slice of the subject, 180 ° excitation is performed on the second slice, and a spin echo generated from a straight line portion where both slices intersect is read as a navigator echo. The position information of the diaphragm can be obtained by subjecting the navigator echo to a one-dimensional Fourier transform in the reading direction.

  The background art will be described with reference to FIG. FIG. 6 shows a profile line PL of the magnetic resonance signal obtained by executing the navigator sequence. The vertical axis in FIG. 6 is the intensity I of the magnetic resonance signal in the profile line PL, and the horizontal axis is shown in the straight line portion where the first slice and the second slice intersect (in the subject SU in FIG. 6A). NA) indicates the position of the horizontal axis x to be a scan line.

  As shown in FIG. 6, in the subject SU, the magnetic resonance signal of the profile line PL appears strongly in the region B where the liver exists. Then, the edge region ΔB where the intensity of the magnetic resonance signal in the profile line PL starts to increase rapidly can be identified as the region where the diaphragm adjacent to the liver is located.

  In order to improve the accuracy of identifying the region where the diaphragm is located, for example, as described in Non-Patent Document 1, the horizontal axis x (scan line) of the profile line PL indicating the intensity of the magnetic resonance signal is continuous. When the intensity of the magnetic resonance signal continuously exceeds a predetermined threshold in the range of ΔB to be performed (see FIG. 6), the range of ΔB is determined as the edge region. The continuous range of ΔB corresponds to continuous pixels in the scan line of the displayed image when the profile line PL indicating the intensity of the magnetic resonance signal is displayed as a slice image.

JP 2002-102201 A JP-T 09-508050 Du YP, Saranathan M, Foo TK.An accurate, robust, and computationally efficient navigator algorithm for measuring positions.J Cardiovasc Magn Reson.2004; 6: 483-490

  As shown in FIG. 6, in the method of identifying the tissue in a predetermined region of the subject by the intensity I of the magnetic resonance signal in the profile line PL of the magnetic resonance signal obtained by performing the navigator sequence, the profile line It is identified that a specific tissue exists at a predetermined position x where the intensity I of the magnetic resonance signal in PL increases. That is, it is identified that there is a substantial tissue in a predetermined region in the subject SU where the intensity I of the magnetic resonance signal increases.

  However, as shown in FIG. 6A, in the subject SU, the substantial tissue includes not only the liver (Liver) but also the lung (Lung), for example. In the lungs, blood constantly flows in the pulmonary artery and pulmonary vein in synchronization with the heartbeat. And blood contains a lot of water. Therefore, by executing the navigator sequence, the magnetic resonance signal profile line PL obtained by the blood flowing through the pulmonary artery and the pulmonary vein is present in the lung as shown in FIG. Also in the region A where it is to be strengthened.

  Here, in order to identify a tissue in a predetermined region of the subject SU based on the intensity of the magnetic resonance signal of the profile line PL, the subject SU is moved in the positive direction from the position x = 0 of the scan line. When identifying the tissue, as shown in FIG. 6 (b), the intensity I of the magnetic resonance signal appears strong for blood in the region A where the lungs first exist, and then the liver exists. In the region B, the intensity I of the magnetic resonance signal may appear strongly.

  For this reason, there is a possibility that the edge region ΔA where the intensity I of the magnetic resonance signal starts to appear first is mistakenly identified as the region where the diaphragm is located. Therefore, the problem to be solved by the present invention is to identify the tissue of the subject based on the profile line of the magnetic resonance signal obtained by executing the navigator sequence in the magnetic resonance imaging apparatus that executes the sequence including the navigator sequence. It is an object of the present invention to provide a magnetic resonance imaging apparatus in which tissue is difficult to be mistakenly recognized when performing.

  The present invention is a magnetic resonance imaging apparatus for generating an image of the subject based on a magnetic resonance signal generated in the subject by irradiating the subject with an RF pulse in a static magnetic field space, A scan unit that executes a sequence including a navigator sequence that obtains the magnetic resonance signal generated in the step, a profile line of the intensity of the magnetic resonance signal obtained by the scan unit executing the navigator sequence, and a magnetic resonance signal An image generation unit that creates a profile line of the phase, information on the intensity indicated in the profile line of the intensity of the magnetic resonance signal generated by the image generation unit, and the phase of the magnetic resonance signal generated by the image generation unit Based on the phase information indicated in the profile line of the subject Having an identification section for identifying a tissue region.

  Preferably, the identification unit determines whether the intensity of the magnetic resonance signal of the profile line corresponding to a specific pixel in the scan line of the profile line of the intensity of the magnetic resonance signal is equal to or higher than a predetermined threshold value. Identify the organization.

  Specifically, the identification unit may determine that the intensity of the magnetic resonance signal of the profile line corresponding to a continuous pixel among the specific pixels in the scan line of the intensity profile line of the magnetic resonance signal is greater than or equal to a predetermined threshold value. The organization is identified by whether or not it is.

  Further, the identification unit identifies the tissue depending on whether or not the standard deviation of the phase of the magnetic resonance signal in the profile line of the phase of the magnetic resonance signal corresponding to the continuous pixel is greater than or equal to a predetermined threshold value. .

  Specifically, the identification unit is configured to detect the continuous pixels when a standard deviation of the phase of the magnetic resonance signal in the profile line of the phase of the magnetic resonance signal corresponding to the continuous pixel is equal to or greater than a predetermined threshold value. The region of the subject included in the scan line corresponding to is excluded from the target for tissue identification.

  The tissue excluded from the target for identifying the tissue in the region of the subject by the identification unit is a blood flow tissue.

Preferably, when the navigator sequence is executed, the scanning unit applies a gradient magnetic field to the subject in advance before obtaining a magnetic resonance signal. More preferably, the gradient magnetic field applied by the scanning unit includes a gradient magnetic field whose polarities are reversed from each other.
Note that the navigator echo of the navigator sequence may employ either a linear excitation spin echo type of 90 ° -180 ° excitation or a gradient echo type.

  In the magnetic resonance imaging apparatus according to the present invention, it is difficult to erroneously recognize the subject tissue when identifying the subject tissue based on the profile line of the magnetic resonance signal obtained by executing the navigator sequence.

  FIG. 1 is a configuration diagram illustrating a configuration of a magnetic resonance imaging apparatus 1 according to the first embodiment of the present invention.

  As shown in FIG. 1, the magnetic resonance imaging apparatus 1 of the present embodiment includes a scanning unit 2 and an operation console unit 3. The scanning unit 2 will be described.

  As shown in FIG. 1, the scanning unit 2 includes a static magnetic field magnet unit 12, a gradient coil unit 13, an RF coil unit 14, a cradle 15, an RF drive unit 22, a gradient drive unit 23, and a data collection unit. 24. The scanning unit 2 transmits an RF pulse to the subject SU so as to excite the spin of the subject SU within the imaging space B in which the static magnetic field is formed, and a gradient is applied to the subject SU to which the RF pulse is transmitted. By transmitting a pulse, an imaging sequence for obtaining magnetic resonance signals generated in the subject SU as imaging data is performed. The imaging sequence performed by the scanning unit 2 includes, for example, an imaging sequence based on a spin echo method and a gradient echo method, and is an imaging sequence that is generally performed normally.

  The scanning unit 2 performs an imaging sequence and also executes a navigator sequence that obtains a magnetic resonance signal that does not give phase encoding in a predetermined region of the subject SU.

  For example, when the navigator sequence performed by the scanning unit 2 is performed, 90 ° excitation is performed on the first slice of the subject SU, 180 ° excitation is performed on the second slice, and the straight portion where both slices intersect is used. The generated spin echo is read as a navigator echo.

Each component of the scanning unit 2 will be described sequentially.
The static magnetic field magnet unit 12 is composed of, for example, a pair of superconducting magnets, and forms a static magnetic field in the imaging space B in which the subject SU is accommodated. Here, the static magnetic field magnet unit 12 forms a static magnetic field such that the static magnetic field direction is along a direction z perpendicular to the body axis direction of the subject SU. In addition, the static magnetic field magnet part 12 may be comprised with the permanent magnet.

  The gradient coil unit 13 forms a gradient magnetic field in the imaging space B in which a static magnetic field is formed, and adds spatial position information to the magnetic resonance signal received by the RF coil unit 14. Here, the gradient coil unit 13 includes three systems so as to correspond to three axial directions orthogonal to each other in the z direction along the static magnetic field direction, the x direction, and the y direction. These form a gradient magnetic field by transmitting gradient pulses as a frequency encode direction, a phase encode direction, and a slice selection direction, respectively, according to imaging conditions.

  Specifically, when performing the imaging sequence, the gradient coil unit 13 applies a gradient magnetic field in the slice selection direction of the subject SU, and the RF coil unit 14 transmits an RF pulse to excite the subject SU. Select a slice. The gradient coil unit 13 applies a gradient magnetic field in the phase encoding direction of the subject SU, and phase encodes the magnetic resonance signal from the slice excited by the RF pulse. The gradient coil unit 13 applies a gradient magnetic field in the frequency encoding direction of the subject SU, and frequency encodes the magnetic resonance signal from the slice excited by the RF pulse.

  Further, when performing the navigator sequence, the gradient coil unit 13 applies a gradient magnetic field in the selection direction of the first slice and the second slice of the subject SU, for example, and the RF coil unit 14 is excited by 90 ° and 180 °. The first and second slices of the subject to be excited are selected by transmitting an excitation RF pulse. When the navigator sequence is performed, only the frequency encoding is performed on the gradient coil unit 13 without performing phase encoding.

  As shown in FIG. 1, the RF coil unit 14 is disposed so as to surround the imaging region of the subject SU. In the imaging space B where the static magnetic field is formed by the static magnetic field magnet unit 12, the RF coil unit 14 transmits an RF pulse, which is an electromagnetic wave, to the subject SU to form a high-frequency magnetic field, and in the imaging region of the subject SU. Excites proton spin. The RF coil unit 14 receives an electromagnetic wave generated from the excited proton in the subject SU as a magnetic resonance signal.

  The cradle 15 has a table on which the subject SU is placed. The cradle 15 moves between the inside and the outside of the imaging space B based on a control signal from the control unit 30.

  The RF drive unit 22 drives the RF coil unit 14 to transmit an RF pulse in the imaging space B to form a high frequency magnetic field. Based on the control signal from the control unit 30, the RF drive unit 22 modulates the signal from the RF oscillator to a signal having a predetermined timing and a predetermined envelope using a gate modulator, and then modulates the signal by the gate modulator. The signal thus amplified is amplified by an RF power amplifier and output to the RF coil unit 14 to transmit an RF pulse.

  Based on a control signal from the control unit 30, the gradient driving unit 23 applies a gradient pulse to the gradient coil unit 13 to drive the gradient coil unit 13, thereby generating a gradient magnetic field in the imaging space B in which a static magnetic field is formed. The gradient drive unit 23 includes three systems of drive circuits (not shown) corresponding to the three systems of gradient coil units 13.

  The data collection unit 24 collects magnetic resonance signals received by the RF coil unit 14 based on the control signal from the control unit 30. Here, in the data collecting unit 24, the phase detector detects the magnetic resonance signal received by the RF coil unit 14 using the output of the RF oscillator of the RF driving unit 22 as a reference signal. Thereafter, the magnetic resonance signal, which is an analog signal, is converted into a digital signal using an A / D converter and output.

The operation console unit 3 will be described.
As illustrated in FIG. 1, the operation console unit 3 includes a control unit 30, an image generation unit 31, an operation unit 32, a display unit 33, and a storage unit 34.

  Each component of the operation console unit 3 will be described sequentially.

  The control unit 30 includes a computer and a program that causes the computer to execute predetermined data processing, and controls each unit. Here, the control unit 30 receives operation data from the operation unit 32, and each of the RF drive unit 22, the gradient drive unit 23, and the data collection unit 24 based on the operation data input from the operation unit 32. In addition to a predetermined normal imaging sequence, a control signal for executing a scan for executing the navigator sequence is output for control. Then, a control signal is output to the image generation unit 31, the display unit 33, and the storage unit 34 to perform control.

  Note that the control unit 30 includes a computer and a program. As described below, when the navigator sequence is performed in the scanning unit, the magnetic field in the profile line of the magnetic resonance signal generated by the image generation unit 31 is used. It functions as an identification unit that identifies tissue in a predetermined region of the subject SU based on information on the intensity of the resonance signal and the phase of the magnetic resonance signal.

  The image generation unit 31 includes a computer and a program that executes predetermined data processing using the computer, and generates an image based on a control signal from the control unit 30. Here, when the imaging sequence is performed in the scan unit 2, the image generation unit 31 uses the magnetic resonance signal obtained by the scan unit 2 performing the scan as raw data, and images the subject SU. Reconfigure. Then, the image generation unit 31 outputs the generated image to the display unit 33.

  In addition, when the navigator sequence is performed in the scan unit 2, the image generation unit 31 performs one-dimensional Fourier transform on the navigator echo read by the scan unit 2 in the read direction, and generates a profile line of the intensity of the magnetic resonance signal. To do. The image generation unit 31 also generates a profile line of the phase of the magnetic resonance signal.

  The operation unit 32 is configured by operation devices such as a keyboard and a pointing device. The operation unit 32 is input with operation data by an operator and outputs the operation data to the control unit 30.

  The display unit 33 is configured by a display device such as a CRT, and displays an image on the display screen based on a control signal from the control unit 30. For example, the display unit 33 displays a plurality of images of input items for which operation data is input to the operation unit 32 by the operator on the display screen. In addition, the display unit 33 receives data about the image of the subject SU generated based on the magnetic resonance signal from the subject SU from the image generation unit 31 and displays the image on the display screen.

  The storage unit 34 includes a memory and stores various data. The storage unit 34 is accessed by the control unit 30 as necessary for the stored data.

  An example of identifying a tissue in a predetermined region of the subject SU by executing a navigator sequence for the subject SU using the magnetic resonance imaging apparatus 1 having the above configuration shown in FIG. Will be described with reference to FIG.

  First, navigator echo data is acquired (ST1). For this purpose, the scan unit 2 measures a magnetic resonance signal that does not give phase encoding in a predetermined region of the subject SU, and executes a navigator sequence that is obtained as navigator echo data.

  For example, in the subject SU of FIG. 3A, a straight line intersecting two cross sections in a direction substantially orthogonal to the diaphragm located between the lung (Lung) and the liver (Liver) is defined as an area NA. The RF coil unit 14 of the scan unit 2 acquires a magnetic resonance signal (navigator echo) having a phase encode of zero from the area NA. Specifically, the RF coil unit 14 of the scan unit 2 performs 90 ° excitation on the first slice of the subject SU, performs 180 ° excitation on the second slice, and starts from a straight line portion where both slices intersect. The RF coil unit 14 reads the generated spin echo as a navigator echo.

  Then, after the navigator echo data acquisition (ST1) is completed, a navigator echo profile is created (ST2). For this purpose, the navigator echo read out by the scanning unit 2 is one-dimensionally Fourier transformed by the image generation unit 31 in the reading direction (the x-axis direction in FIG. 3A), and the profile line of the intensity of the magnetic resonance signal ( 3B) and a profile line of the phase of the magnetic resonance signal (FIG. 3C) are generated. Such processing is performed by the computer of the image generation unit 31 according to a program.

  The predetermined position on the scan line (horizontal axis x) where the profile line PL shown in FIGS. 3B and 3C is shown is the horizontal axis of the slice image when the profile line PL is displayed as a slice image. It corresponds to a pixel at a predetermined position in the direction.

  Next, the edge detection (STE) of the tissue existing in the subject SU is performed based on the profile line PL of the intensity of the magnetic resonance signal obtained by creating the navigator profile (ST2). Edge detection is performed by measuring the intensity I sequentially from zero toward the positive direction on the horizontal axis x in FIG. 3B showing the intensity I of the magnetic resonance signal in the profile line PL. The intensity I is measured by the computer of the control unit 30 using the profile I intensity data generated by the image generation unit 31 according to a program.

  Here, in measuring the intensity I, the intensity I of a specific continuous range is indicated on the horizontal axis x indicating the intensity I of the magnetic resonance signal of the profile line PL of the intensity of the magnetic resonance signal shown in FIG. If all are equal to or greater than the predetermined threshold, the control unit 30 determines that the tissue edge has been detected in the subject SU.

  As described above, the predetermined position on the horizontal axis x where the profile line PL of the intensity of the magnetic resonance signal shown in FIG. 3B is shown is the horizontal position of the slice image when the profile line PL is displayed as a slice image. It corresponds to a pixel at a predetermined position in the axial direction. Therefore, a specific continuous range on the horizontal axis x of the scan line corresponds to a specific continuous pixel in the horizontal axis direction of the slice image. Here, the pixels in the continuous scanning direction are set as specific pixels.

  In the tissue edge detection (STE), the computer of the control unit 30 extracts specific pixels of the magnetic resonance signal intensity profile line PL from zero to the positive direction on the x axis of the magnetic resonance signal intensity profile line PL. (ST3) is performed. Then, the signal intensity I is measured (ST4) at the specific pixel.

  In the case of FIG. 3B, when a specific pixel is extracted from zero toward the positive direction on the x axis of the profile line PL of the intensity of the magnetic resonance signal, first, it is indicated by ΔA on the x axis. A specific pixel in a range in a direction negative to the range is extracted, then a specific pixel in a range indicated by ΔA is extracted, and a specific pixel between the ranges indicated by ΔA and ΔB is extracted, Finally, specific pixels in the range indicated by ΔB are extracted.

  The signal intensity I is measured for specific pixels represented by these four (ST4), and the control unit 30 determines whether the signal intensity I is equal to or higher than the threshold value Ith (ST5). .

  As shown in FIG. 3B, the signal intensity I is weak in a specific pixel in the negative direction range than the range indicated by ΔA, and is equal to or less than the threshold value Ith (ST5). Therefore, a specific pixel in the range indicated by the next ΔA is extracted (ST3). In the area of the specific pixel in the range indicated by ΔA, there is a pulmonary blood vessel in the lung (Lung), and the signal intensity I becomes stronger due to the blood of the pulmonary blood vessel, and its value is equal to or greater than Ith (ST5). Therefore, the control unit 30 determines that the pulmonary blood vessel edge has been detected in the subject SU, and proceeds to the next ST6.

  In ST6, the control unit 30 calculates the standard deviation σ of the phase φ of the magnetic resonance signal in the specific pixel in the range indicated by ΔA. Here, in the range indicated by ΔA, a pulmonary blood vessel exists in the subject SU, a magnetic resonance signal from the blood of the pulmonary blood vessel is detected, and the signal intensity I is strong as shown in FIG. It becomes.

  However, since the blood in the pulmonary blood vessels in the lungs constantly flows in the blood vessels in synchronization with the heartbeat and moves, the phase φ of the magnetic resonance signal mainly composed of components from the blood is shown in FIG. As shown, there is a large variation. Therefore, the standard deviation σ of the phase φ of the magnetic resonance signal calculated in ST6 becomes large, and the standard deviation σ becomes equal to or larger than a predetermined standard deviation threshold σth as shown in FIG.

  Therefore, as in ST8, the control unit 30 determines that the tissue of the subject SU in the range indicated by ΔA is a blood flow tissue. Then, as in ST9, the control unit 30 excludes the tissue of the subject SU in the range indicated by ΔA from identification. By doing so, the range indicated by ΔA is not erroneously identified as the region where the diaphragm is located.

  Subsequently, extraction of specific pixels (ST3) is continued, and specific pixels in a range indicated by ΔB are extracted. In the specific pixel region in the range indicated by ΔB, there is a liver (Liver), and the signal intensity I becomes strong, so that the value is equal to or greater than Ith (ST5). For this reason, the control unit 30 determines that the liver edge has been detected in the subject SU, and proceeds to the next ST6.

  In ST6, the control unit 30 calculates the standard deviation σ of the phase φ of the magnetic resonance signal in the specific pixel in the range indicated by ΔB. Here, the range indicated by ΔB has a liver in the subject SU, and its signal intensity I is strong as shown in FIG.

  The liver substance is a hepatocyte mass, and the blood flow in the liver is gentler than that in the lung. Therefore, it can be considered that the liver is almost free of movement, and the phase φ of the magnetic resonance signal monotonously increases toward the positive direction of the x-axis as shown in FIG. It will be a thing. Therefore, the standard deviation σ of the phase φ of the magnetic resonance signal calculated in ST6 is very small, and the standard deviation σ is equal to or smaller than a predetermined standard deviation threshold σth as shown in FIG. .

  Therefore, the control unit 30 does not determine that the tissue of the subject SU in the range indicated by ΔB as in ST8 is a blood flow tissue, but indicates the position of ΔB in the x-axis direction (ST10). Note that if the control unit 30 recognizes that the region where the diaphragm is located at the position of ΔB in the x-axis direction in accordance with a program incorporated in advance, the x-axis of ΔB shown in ST10 Information on the position in the direction makes it possible to reliably identify the location where the diaphragm is located.

  In the navigator echo described above, the RF coil unit 14 of the scan unit 2 performs 90 ° excitation for the first slice of the subject SU, performs 180 ° excitation for the second slice, and both slices intersect. The RF coil unit 14 reads out the spin echo generated from the straight line portion as a navigator echo, and is a 90 ° -180 ° linearly excited spin echo type navigator echo. For example, the navigator echo has a pulse sequence shown in FIG.

  However, the navigator echo is not limited to the spin echo type, and may be a gradient echo type. For example, there is the one shown in the pulse sequence of FIG. In the pulse sequence of FIG. 5, when transmitting an RF pulse, the gradient coil unit 13 of the scan unit 2 applies so that the polarity changes alternately and selects slices of the subject in a linear form. To do.

  Then, after transmitting the RF pulse, the gradient coil unit 13 sequentially applies a gradient magnetic field G + having a positive polarity and a gradient magnetic field G− having a negative polarity. Thus, by applying the gradient magnetic fields G + and G− whose polarities are reversed to each other, the dispersion of the phase φ of the magnetic resonance signal from the tissue of the blood flow is promoted, and the standard deviation can be increased. . This improves the accuracy of tissue type identification.

1 is a diagram showing a configuration of a magnetic resonance imaging apparatus in an embodiment according to the present invention. It is a flowchart of the sequence which performs a navigator echo in the magnetic resonance imaging apparatus concerning embodiment of this invention. In the magnetic resonance imaging apparatus concerning embodiment of this invention, it is the figure which plotted the intensity | strength of the magnetic resonance signal in the profile line of the magnetic resonance signal obtained by implementing navigator sequence, and the phase of a magnetic resonance signal. It is the figure which showed the example of the pulse sequence in the case of performing a spin echo type navigator echo in the magnetic resonance imaging apparatus concerning embodiment of this invention. It is the figure which showed the example of the pulse sequence in the case of performing a gradient echo type navigator echo in the magnetic resonance imaging apparatus concerning embodiment of this invention. It is the figure which plotted the intensity | strength of the magnetic resonance signal in the profile line of the magnetic resonance signal obtained by implementing a navigator sequence in the conventional magnetic resonance imaging apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Magnetic resonance imaging apparatus, 2 ... Scan part, 3 ... Operation console part, 12 ... Static magnetic field magnet part, 13 ... Gradient coil part, 14 ... RF coil part, 15 ... Cradle, 22 ... RF drive part, 23 ... Gradient Drive unit, 24... Data collection unit, 30... Control unit (identification unit), 31... Image generation unit, 32 ... operation unit, 33 ... display unit, 34 ... storage unit, B ... imaging space

Claims (9)

A magnetic resonance imaging apparatus for generating an image of the subject based on a magnetic resonance signal generated in the subject by irradiating the subject with an RF pulse in a static magnetic field space,
A scan unit for executing a sequence including a navigator sequence for obtaining the magnetic resonance signal generated in the subject;
A profile generator for creating a magnetic resonance signal intensity profile obtained by the scan unit performing the navigator sequence, and a phase profile of the magnetic resonance signal;
The predetermined region of the subject based on the intensity information in the intensity profile of the magnetic resonance signal generated by the profile generation unit and the phase information in the phase profile of the magnetic resonance signal generated by the profile generation unit An identification unit for identifying
A magnetic resonance imaging apparatus. The magnetic resonance according to claim 1, wherein the identification unit identifies the region based on whether or not the intensity of the magnetic resonance signal of the profile corresponding to a predetermined position in the subject is equal to or greater than a predetermined threshold. Imaging device. The magnetic field according to claim 2, wherein the identification unit identifies the region based on whether or not the intensity of the magnetic resonance signal of the profile corresponding to a position in a predetermined range in the subject is equal to or greater than a predetermined threshold value. Resonance imaging device. 4. The identification unit according to claim 3, wherein the identification unit identifies the region based on whether or not a standard deviation of a phase of a magnetic resonance signal of the profile corresponding to a position in a predetermined range in the subject is greater than or equal to a predetermined threshold value. The magnetic resonance imaging apparatus described. When the standard deviation of the phase of the magnetic resonance signal of the profile corresponding to the position of the predetermined range in the subject is greater than or equal to a predetermined threshold, the identifying unit determines the region for the predetermined range in the subject. The magnetic resonance imaging apparatus according to claim 4, wherein the magnetic resonance imaging apparatus is excluded from an object to be identified. The magnetic resonance imaging apparatus according to claim 5, wherein a magnetic resonance signal due to blood flow is included in the profile in a predetermined range in the subject excluded from a target for identifying the region by the identification unit. The magnetic resonance imaging apparatus according to claim 1, wherein the scan unit applies a gradient magnetic field to the subject in advance before obtaining a magnetic resonance signal when a navigator sequence is performed. The magnetic resonance imaging apparatus according to claim 7, wherein the gradient magnetic field applied by the scan unit includes gradient magnetic fields having polarities reversed to each other. 9. The magnetic resonance imaging apparatus according to claim 1, wherein a navigator echo of the navigator sequence is a linearly excited spin echo type or a gradient echo type of 90 ° -180 ° excitation.

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