JP2008212449A - Magnetic resonance imaging apparatus and magnetic resonance imaging data processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To display the distribution of sensitivity of a phased array coil, and to easily and accurately display the location of the phased array coil. <P>SOLUTION: In the magnetic resonance imaging apparatus related to this invention, a sequence controller control part 41 controls execution of dynamic scanning by using the phased array coil, and a sensitivity map generating part 42 generates the sensitivity map of the phased array coil when the dynamic scanning is executed by using the phased array coil. A sensitivity distribution generating part 43 generates the sensitivity distribution indicating the variation of the signal intensity in the encoding direction based on the rate of change of the signal strength or signal phase in the generated sensitivity map, and a coil location computing part 44 computes the locations of respective surface coils, which constitute the phased array coil, by using the generated sensitivity distribution. A display device 34 superimposes/displays the sensitivity distribution on the sensitivity map according to the control of the display control part 45 and according to the computed locations of the surface coils. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a magnetic resonance imaging apparatus and a magnetic resonance imaging data processing method, and more particularly, to a magnetic resonance imaging apparatus and a magnetic resonance imaging data processing method capable of displaying the position of a phased array coil.

  Magnetic resonance (MR) imaging uses a high-frequency signal of the Larmor frequency to periodically excite the nuclear spin of an object placed in a static magnetic field, and reconstructs the image using the NMR signal generated by this excitation. This is an imaging method. Magnetic resonance imaging devices that implement this imaging method are now an essential medical modality.

  In recent years, in a magnetic resonance imaging apparatus, a signal from the vicinity of the body surface of a subject can be detected efficiently, and the area contributed by noise can be kept small, so that a high signal-to-noise ratio (Signal to Noise Ratio) can be obtained. Possible surface coils are being used. In particular, a phased array coil (PAC) formed by arranging a plurality of surface coils at a desired position has been proposed, which makes it possible to use a single coil of the same size. A higher SN ratio and a wider sensitivity range can be obtained.

  By the way, in a magnetic resonance imaging apparatus, in order to make the S / N ratio of the NMR signal obtained from each surface coil suitable, it is necessary to obtain the sensitivity distribution of each surface coil in advance and detect the position of each surface coil. .

  Therefore, a technique for detecting the position of each surface coil has been proposed (see, for example, Patent Documents 1 to 2).

In addition, a technique for displaying the position of the phased array coil using the position information of the surface coil whose geometric position in the magnetic resonance imaging apparatus is known in advance has been proposed.
JP-A-4-138133 JP 2003-38458 A

  However, in the conventional technology, among the phased array coils, it is possible to display the position of the phased array coil using the position information of the surface coil whose geometric position in the magnetic resonance imaging apparatus is known in advance. The phased array coil whose position is displayed is limited to the surface coil whose geometric position in the magnetic resonance imaging apparatus is known in advance, or, for example, the position of the movable surface coil with respect to the subject is changed. There was a problem that it was difficult to accurately detect and display.

  In addition, when detecting the position of the surface coil, the sensitivity distribution of each surface coil itself is not displayed, and it is difficult for the operator to grasp the actual sensitivity distribution of each surface coil. .

  The present invention has been made in view of such a situation, and displays a sensitivity distribution of the phased array coil and can accurately and easily display the position of the phased array coil. It is another object of the present invention to provide a magnetic resonance imaging data processing method.

  In order to solve the above-described problems, a magnetic resonance imaging apparatus of the present invention controls a dynamic scan using a phased array coil by using a phased array coil, and performs a dynamic scan using the phased array coil by the control means. In this case, the first generation means for generating the sensitivity map of the phased array coil, and the change in the signal strength in the encoding direction based on the change rate of the signal intensity or the signal phase in the sensitivity map generated by the first generation means. A first generation unit that generates a sensitivity distribution indicating the position, a first calculation unit that calculates the position of each surface coil that forms the phased array coil, using the sensitivity distribution generated by the second generation unit; The sensitivity distribution is superimposed and displayed on the sensitivity map according to the position of the surface coil calculated by the first calculation means. Characterized in that it comprises a display means that.

  In order to solve the above-described problems, the magnetic resonance imaging apparatus of the present invention has a control unit that controls execution of a dynamic scan using a phased array coil, and a dynamic scan that uses the phased array coil by the control unit. In addition, a first generation unit that generates a G-Factor of the phased array coil and a second distribution that generates a sensitivity distribution indicating a change in sensitivity in the encoding direction based on the G-Factor generated by the first generation unit. The first calculating means for calculating the position of each surface coil forming the phased array coil using the sensitivity distribution generated by the generating means, the second generating means, and the first calculating means Display means for superimposing and displaying the sensitivity distribution on the G-Factor according to the position of the surface coil. And butterflies.

  In order to solve the above-described problems, a magnetic resonance imaging data processing method of the present invention controls a dynamic scan using a phased array coil using a phased array coil, and dynamically uses a phased array coil obtained by the process of the control step. A first generation step for generating a sensitivity map of the phased array coil during execution of the scan, and encoding based on the rate of change of the signal intensity or signal phase in the sensitivity map generated by the processing of the first generation step The position of each surface coil forming the phased array coil is calculated using a second generation step for generating a sensitivity distribution indicating a change in signal strength in the direction and the sensitivity distribution generated by the processing of the second generation step. First calculation step to be performed and calculation by the processing of the first calculation step According to the position of the surface coil, characterized in that it comprises a display step of displaying by superimposing the sensitivity distribution on the sensitivity map.

  In order to solve the above-described problems, a magnetic resonance imaging data processing method according to the present invention includes a control step for controlling execution of a dynamic scan using a phased array coil, and a dynamic scan using a phased array coil by the processing of the control step. The first generation step for generating the G-Factor of the phased array coil and the sensitivity indicating the change in the sensitivity in the encoding direction based on the G-Factor generated by the processing of the first generation step A second generation step for generating a distribution; a first calculation step for calculating the position of each surface coil forming the phased array coil using the sensitivity distribution generated by the processing of the second generation step; According to the position of the surface coil calculated by the processing of the calculation step 1, the G- Characterized in that it comprises a display step of displaying by superimposing the sensitivity distribution on the actor.

  In the magnetic resonance imaging apparatus of the present invention, the execution of the dynamic scan is controlled using the phased array coil, and the sensitivity map of the phased array coil is generated and generated when the dynamic scan is executed using the phased array coil. A sensitivity distribution indicating a change in signal intensity in the encoding direction is generated based on the rate of change in signal intensity or signal phase in the sensitivity map, and the generated sensitivity distribution is used to generate a phased array coil for each surface coil. The position is calculated, and the sensitivity distribution is superimposed and displayed on the sensitivity map according to the calculated position of the surface coil.

  In the magnetic resonance imaging apparatus of the present invention, the execution of the dynamic scan is controlled using the phased array coil, and the G-Factor of the phased array coil is generated and generated when the dynamic scan is executed using the phased array coil. Based on the G-Factor, a sensitivity distribution indicating a change in sensitivity in the encoding direction is generated, and the position of each surface coil forming the phased array coil is calculated using the generated sensitivity distribution. The sensitivity distribution is superimposed and displayed on the G-Factor according to the position of the surface coil.

  In the magnetic resonance imaging data processing method of the present invention, the execution of the dynamic scan is controlled using the phased array coil, and the sensitivity map of the phased array coil is generated when the dynamic scan is executed using the phased array coil. Based on the signal intensity or signal phase change rate in the generated sensitivity map, a sensitivity distribution indicating a change in signal intensity in the encoding direction is generated, and each surface forming the phased array coil using the generated sensitivity distribution The position of the coil is calculated, and the sensitivity distribution is superimposed and displayed on the sensitivity map according to the calculated position of the surface coil.

  In the magnetic resonance imaging data processing method of the present invention, the execution of the dynamic scan is controlled using the phased array coil, and the G-Factor of the phased array coil is generated when the dynamic scan is executed using the phased array coil. Based on the generated G-Factor, a sensitivity distribution indicating a change in sensitivity in the encoding direction is generated, and the position of each surface coil forming the phased array coil is calculated using the generated sensitivity distribution. The sensitivity distribution is superimposed and displayed on the G-Factor according to the position of the surface coil.

  According to the present invention, the position of the phased array coil can be accurately and easily displayed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a configuration of a magnetic resonance imaging apparatus 20 according to the present invention.

  As shown in FIG. 1, the magnetic resonance imaging apparatus 20 includes a cylindrical static magnetic field magnet 21 that forms a static magnetic field, a shim coil 22 provided inside the static magnetic field magnet 21, a gradient magnetic field coil unit 23, And an RF coil unit 24. These units are built in a gantry (not shown) of the magnetic resonance imaging apparatus 20.

  The magnetic resonance imaging apparatus 20 includes a control system 25. The control system 25 includes a static magnetic field power supply 26, a gradient magnetic field power supply 27, a shim coil power supply 28, a transmitter 29, a receiver 30, a sequence controller 31, and a computer 32. The gradient magnetic field power source 27 of the control system 25 includes an X-axis gradient magnetic field power source 27x, a Y-axis gradient magnetic field power source 27y, and a Z-axis gradient magnetic field power source 27z. In addition, the computer 32 includes an input device 33, a display device 34, an arithmetic device 35, and a storage device 36.

  The static magnetic field magnet 21 is connected to a static magnetic field power supply 26, and the static magnetic field magnet 21 forms a static magnetic field in the imaging region by a current supplied from the static magnetic field power supply 26. In many cases, the static magnetic field magnet 21 is composed of a superconducting coil. Generally, the static magnetic field magnet 21 is connected to a static magnetic field power source 26 at the time of excitation. A current is supplied to the working magnet 21, but after being excited once, the static magnetic field magnet 21 and the static magnetic field power supply 26 are disconnected. Alternatively, the static magnetic field magnet 21 may be constituted by a permanent magnet, and the static magnetic field power supply 26 may not be provided.

  A cylindrical shim coil 22 is coaxially provided inside the static magnetic field magnet 21. The shim coil 22 is connected to a shim coil power supply 28, and a static magnetic field is made uniform by a current supplied from the shim coil power supply 28.

  The gradient magnetic field coil unit 23 includes an X-axis gradient magnetic field coil 23 x, a Y-axis gradient magnetic field coil 23 y, and a Z-axis gradient magnetic field coil 23 z, and is formed in a cylindrical shape inside the static magnetic field magnet 21. A bed 37 is provided inside the gradient magnetic field coil unit 23, the subject P is set on the bed 37, and an area inside the gradient magnetic field coil unit 23 is an imaging area. The RF coil unit 24 may be provided in the vicinity of the bed 37 or the subject P without being built in a gantry (not shown).

  The gradient magnetic field coil unit 23 is connected to a gradient magnetic field power supply 27. That is, the X-axis gradient magnetic field coil 23x, the Y-axis gradient magnetic field coil 23y, and the Z-axis gradient magnetic field coil 23z of the gradient magnetic field coil unit 23 are respectively an X-axis gradient magnetic field power supply 27x and a Y-axis gradient magnetic field power supply. 27y and a Z-axis gradient magnetic field power supply 27z.

  The X-axis gradient magnetic field power source 27x, the Y-axis gradient magnetic field power source 27y, and the Z-axis gradient magnetic field power source 27z are supplied with currents supplied to the X-axis gradient magnetic field coil 23x, the Y-axis gradient magnetic field coil 23y, and the Z-axis gradient magnetic field coil 23z, respectively. A gradient magnetic field Gx in the X-axis direction, a gradient magnetic field Gy in the Y-axis direction, and a gradient magnetic field Gz in the Z-axis direction are formed in the imaging region inside the gradient magnetic field coil unit 23, respectively.

  The RF coil unit 24 is connected to the transmitter 29 and the receiver 30. The RF coil unit 24 receives a high-frequency signal from the transmitter 29 and transmits the high-frequency signal to the subject P, and receives an NMR signal generated along with excitation by the high-frequency signal of the nuclear spin inside the subject P.

  FIG. 2 shows a detailed configuration of the RF coil unit 24 of FIG. 3 shows an arrangement example of the surface coil 24c provided on the body surface side of the subject P shown in FIG. 2, and FIG. 4 shows the surface provided on the back side of the subject P shown in FIG. The example of arrangement | positioning of the coil 24c is shown.

  As shown in FIG. 2, the RF coil unit 24 includes a cylindrical whole-body (WB) coil 24a and a phased array coil 24b. The phased array coil 24b includes a plurality of surface coils 24c, and a plurality of these surface coils 24c are arranged on the body surface side and the back surface side of the subject P, respectively.

  For example, as shown in FIG. 3, a total of 32 surface coils 24c, for example, four rows in the x direction and eight rows in the z direction are arranged on the body surface side of the subject P so as to cover a wide range of imaging regions. Is done. For example, as shown in FIG. 4, a total of 32 surface coils, for example, 4 rows in the x direction and 8 rows in the z direction so that a wide range of imaging regions are similarly covered on the back side of the subject P. 24c is arranged. On the back side, a surface coil 24c smaller than the other surface coils 24c is arranged near the body axis from the viewpoint of improving sensitivity in consideration of the presence of the spine of the subject P.

  On the other hand, the receiver 30 includes a duplexer 30a, an amplifier 30b, a switching synthesizer 30c, and a receiving system circuit 30d. The duplexer 30a is connected to the transmitter 29, the WB coil 24a, and the amplifier 30b for the WB coil 24a. The amplifiers 30b are provided by the number of the surface coils 24c and the WB coils 24a, and are individually connected to the surface coils 24c and the WB coils 24a. The switching synthesizer 30c is provided singly or in plural, and the input side of the switching synthesizer 30c is connected to the plurality of surface coils 24c or the WB coil 24a via the plurality of amplifiers 30b. A desired number of reception system circuits 30d are provided so as to be equal to or less than the number of each surface coil 24c and WB coil 24a, and are provided on the output side of the switching synthesizer 30c.

  The WB coil 24a can be used as a coil for transmitting a high-frequency signal. The WB coil 24a can also be used as a receiving coil. Of course, each surface coil 24c may be used as a coil for receiving NMR signals.

  For this reason, the duplexer 30a applies the high-frequency signal for transmission output from the transmitter 29 to the WB coil 24a, while switching and synthesizing the NMR signal received by the WB coil 24a via the amplifier 24d in the receiver 30. It is comprised so that it may give to the container 30c. Further, the NMR signals received by the surface coils 24c are also output to the switching synthesizer 30c via the corresponding amplifiers 24d.

  The switching synthesizer 30c is configured to perform synthesis processing and switching of NMR signals received from the surface coil 24c and the WB coil 24a and to output them to the corresponding receiving system circuit 30d. In other words, the NMR signal received from the surface coil 24c or the WB coil 24a is synthesized and switched in the switching synthesizer 30c in accordance with the number of the receiving system circuits 30d, and photographing is performed using a desired plurality of surface coils 24c. A sensitivity distribution corresponding to the part is formed so that NMR signals from various imaging parts can be received.

  However, the NMR signal may be received only by the WB coil 24a without providing the surface coil 24c. Further, the NMR signal received by the surface coil 24c or the WB coil 24a may be directly output to the reception system circuit 30d without providing the switching synthesizer 30c. Furthermore, more surface coils 24c can be arranged over a wide range.

  FIG. 5 shows another arrangement example of the surface coil 24c provided on the body surface side of the subject P shown in FIG. 2, and FIG. 6 is provided on the back side of the subject P shown in FIG. The example of another arrangement | positioning of the surface coil 24c is shown.

  As shown in FIGS. 5 and 6, more surface coils 24 c can be arranged around the subject P. For example, in the case of FIG. 5, three coil units 24d composed of 16-element surface coils 24c in four rows in the x direction and four rows in the z direction are arranged in the z direction. Is provided on the body surface side of the subject P. For example, in the case of FIG. 6, a coil unit 24e composed of 32 elements of surface coils 24c in 4 rows in the x direction and 8 rows in the z direction is provided with a surface coil 24c of 2 elements (not shown) on the spine side. Since the coil unit 24f is located near the jaw and the coil unit 24g having 12 surface coils 24c (not shown) is located on the head, a total of 46 surface coils 24c are provided on the back side of the subject P. It is done. As shown in FIGS. 5 and 6, if the surface coil 24c is arranged on the body surface side and the back surface side of the subject P, a total of 94 surface coil 24c is arranged around the subject P. Become. Each surface coil 24c is connected to a dedicated amplifier 30b via a coil port (not shown).

  Then, by arranging a number of surface coils 24c around the subject P, a phased array for the whole body capable of receiving data from a plurality of imaging regions without moving the position of the coil or the subject P. The coil 24b can be formed. The WB coil 24a can receive data from a plurality of imaging regions without moving the position of the coil or the subject P, but if the phased array coil 24b for the whole body is used as a receiving coil, It is possible to receive data with a sensitivity suitable for the imaging region and a better signal to noise ratio (SNR).

  On the other hand, returning to FIG. 1, the sequence controller 31 of the control system 25 is connected to the gradient magnetic field power supply 27, the transmitter 29 and the receiver 30. The sequence controller 31 controls the control information necessary for driving the gradient magnetic field power supply 27, the transmitter 29, and the receiver 30, for example, operation control such as the intensity, application time, and application timing of the pulse current to be applied to the gradient magnetic field power supply 27. The sequence information describing the information is stored, and the gradient magnetic field power source 27, the transmitter 29, and the receiver 30 are driven in accordance with the stored predetermined sequence, whereby the X-axis gradient magnetic field Gx, the Y-axis gradient magnetic field Gy, and the Z-axis gradient A magnetic field Gz and a high frequency signal are generated.

  The sequence controller 31 receives raw data that is complex data obtained by detection of the NMR signal and A / D conversion in the receiver 30 and outputs the received raw data to the computer 32.

  Therefore, the transmitter 29 is provided with a function of giving a high frequency signal to the RF coil unit 24 based on the control information received from the sequence controller 31, while the receiver 30 has an NMR signal received from the RF coil unit 24. Is provided with a function of generating raw data, which is digitized complex data, and a function of supplying the generated raw data to the sequence controller 31 by executing the required signal processing and A / D conversion. It is done.

  Further, the magnetic resonance imaging apparatus 20 includes an ECG unit 38 that acquires an ECG signal of the subject P. The ECG signal acquired by the ECG unit 38 is configured to be output to the computer 32 via the sequence controller 31. In addition, the bed 37 includes a bed driving device 39. The bed driving device 39 is connected to the computer 32, and is configured to be able to perform imaging by the moving table method or the stepping-table method by moving the table of the bed 37 under the control of the computer 32. . The moving table method is a technique for obtaining a large field of view (FOV) in the moving direction by continuously moving the top plate of the bed 37 during photographing. The stepping-table method is a technique for performing 3D (dimensional) imaging by stepping the top plate of the bed 37 for each station. These techniques are used when performing imaging of a wide area that cannot be captured at a time, such as whole body imaging. A plurality of images collected by moving the bed 37 can be connected to each other by a composition process in the computer 32.

  The computing device 35 of the computer 32 includes, for example, a CPU (Central Processing Unit) and the like, executes various processes according to programs stored in the storage device 36 of the computer 32, and generates various control signals. By supplying to each part, the magnetic resonance imaging apparatus 20 is comprehensively controlled. Of course, the computer 32 may be configured by providing a specific circuit regardless of the program.

  FIG. 7 shows a functional configuration that can be executed by the computer 32 of the magnetic resonance imaging apparatus 20 of FIG.

  The sequence controller control unit 41 comprehensively controls the driving of the sequence controller 31 based on various information input by operating the input device 33 by the operator. The sequence controller control unit 41 gives a sequence such as EPI (Echo Planar Imaging) or PI (Parallel Imaging) which is imaging using the phased array coil 24b to the sequence controller 31 to execute dynamic scanning.

  The sensitivity map generation unit 42 acquires the raw data (raw data) supplied from the sequence controller 31 via the sequence controller control unit 41, arranges the obtained raw data in the k space (Fourier space), and arranges the arrangement. A sensitivity map is generated by performing predetermined signal processing on the generated raw data, and the generated sensitivity map is supplied to the sensitivity distribution generation unit 43 and the display control unit 45.

  The sensitivity distribution generation unit 43 acquires the sensitivity map supplied from the sensitivity map generation unit 41, generates a sensitivity distribution indicating a change in signal strength in the encoding direction based on each signal strength in the acquired sensitivity map, The generated sensitivity distribution is supplied to the coil position calculation unit 44 and the display control unit 45.

  The coil position calculation unit 44 acquires the sensitivity distribution supplied from the sensitivity distribution generation unit 43, and determines the position of each surface coil 24c forming the phased array coil 24b by a predetermined calculation method using the acquired sensitivity distribution. The calculated data relating to the calculated position of each surface coil 24c is supplied to the display control unit 45.

  The display control unit 45 acquires the sensitivity map supplied from the sensitivity map generation unit 42 and acquires the sensitivity distribution supplied from the sensitivity distribution generation unit 43. Further, the display control unit 45 acquires the calculation data regarding the position of each surface coil 24c supplied from the coil position calculation unit 44, and the sensitivity distribution on the sensitivity map according to the acquired calculation data regarding the position of each surface coil 24c. Are superimposed and displayed on the display device 34.

  Next, the coil position display process in the magnetic resonance imaging apparatus 20 of FIG. 7 will be described with reference to the flowchart of FIG. The coil position display process is started when an instruction to start the coil position display process is received by operating the input device 33 by the operator.

  In step S <b> 1, the sequence controller control unit 41 determines whether or not an instruction to start the coil position display process is accepted by operating the input device 33 by the operator, and the coil position display process is started. Wait until it is determined that the instruction has been accepted.

  If it is determined in step S1 that an instruction to start the coil position display process has been received, the sequence controller control unit 41 performs phased conversion in step S2 in the selection range selected by operating the input device 33 by the operator. A sequence of PI (Parallel Imaging), which is imaging using the array coil 24b, is given to the sequence controller 31 to execute dynamic scanning.

  Thereafter, the sequence controller control unit 41 sequentially acquires the raw data, which is complex data supplied from the sequence controller 31, and supplies the acquired raw data to the sensitivity map generation unit 42.

  In step S3, the sensitivity map generation unit 42 acquires raw data supplied from the sequence controller 31 via the sequence controller control unit 41, and places the acquired raw data in the k space (Fourier space). In addition, a sensitivity map is generated by performing predetermined signal processing on the arranged raw data, and the generated sensitivity map is supplied to the sensitivity distribution generation unit 43 and the display control unit 45.

  In step S4, the sensitivity distribution generation unit 43 acquires the sensitivity map supplied from the sensitivity map generation unit 41, and based on each signal intensity in the acquired sensitivity map, the sensitivity distribution indicating a change in the signal intensity in the encoding direction. Is generated.

  For example, the signal strength in the readout encoding direction in the sensitivity map is sequentially added, and the added signal strength in the readout encoding direction is used as the sensitivity at a predetermined position in the phase encoding direction, and the signal strength in the encoding direction (for example, the phase encoding direction) changes. For example, sensitivity distributions as indicated by hatched portions a to d in FIG. 9 are generated. The encoding direction may be not only the phase encoding direction but also the slice encoding direction.

  The sensitivity distribution generation unit 43 supplies the generated sensitivity distribution to the coil position calculation unit 44 and the display control unit 45.

  In step S5, the coil position calculation unit 44 acquires the sensitivity distribution supplied from the sensitivity distribution generation unit 43, and uses the acquired sensitivity distribution to form each surface coil that forms the phased array coil 24b by a predetermined calculation method. The position of 24c (for example, the center position of each surface coil 24c, etc.) is calculated.

  Specifically, the coil position calculation unit 44 calculates the correlation coefficient by comparing the set value of the sensitivity distribution that each surface coil 24c has in advance with the actually generated sensitivity distribution. As shown in FIG. 10, the position of each surface coil 24c (for example, the center position of each surface coil 24c) is calculated with reference to the calculated correlation coefficient. Of course, the sensitivity distribution actually obtained using a phantom may be used instead of the preset value of the sensitivity distribution that each surface coil 24c has in advance.

  Since the inside of the actual subject P is not uniform while the inside of the phantom is uniform, the sensitivity distribution actually generated is different from the sensitivity distribution actually obtained using the phantom, It is influenced by the proton density of the subject P. Therefore, when calculating the position of each surface coil 24c (for example, the center position of each surface coil 24c, etc.) using the sensitivity distribution actually obtained using the phantom, a sensitivity map is generated using the WB coil 24a. The sensitivity distribution using the surface coil 24c is actually corrected based on the sensitivity map using the corrected WB coil 24a, the sensitivity distribution using the corrected surface coil 24c, and the sensitivity actually obtained using the phantom. The correlation coefficient may be calculated by comparing with the distribution, and the position of each surface coil 24c may be calculated with reference to the calculated correlation coefficient. Of course, conversely, the sensitivity distribution actually obtained using the phantom may be corrected and compared based on the sensitivity map using the generated WB coil 24a.

  In addition, when calculating the position of each surface coil 24c (for example, the center position of each surface coil 24c), a sensitivity distribution indicating a change in signal intensity in the encoding direction (for example, the phase encoding direction) is used. The sensitivity distribution generation unit 43 may generate a sensitivity distribution indicating the rate of change of the signal phase in the encoding direction (for example, the phase encoding direction), and the sensitivity distribution may be used.

  The coil position calculation unit 44 supplies calculation data regarding the calculated position of each surface coil 24 c to the display control unit 45. The calculation data relating to the position of each surface coil 24c includes data relating to the relative position of each surface coil 24c with respect to the magnetic resonance imaging apparatus 20, data relating to the relative position of each surface coil 24c to the subject P, and the like. include.

  In step S <b> 6, the display control unit 45 acquires the sensitivity map supplied from the sensitivity map generation unit 42 and acquires the sensitivity distribution supplied from the sensitivity distribution generation unit 43. In addition, the display control unit 45 acquires calculation data regarding the position of each surface coil 24c supplied from the coil position calculation unit 44, and the sensitivity distribution has a predetermined position according to the acquired calculation data regarding the position of each surface coil 24c. So as to be superimposed on the sensitivity map and displayed on the display device 34.

  The display device 34 superimposes and displays the sensitivity distribution on the sensitivity map so that the sensitivity distribution is at a predetermined position. For example, as shown in FIG. 11, the sensitivity distribution is superimposed and displayed on the sensitivity map so that the sensitivity distribution is at a predetermined position. In the example of FIG. 11, the color and gradation are changed in the depth direction and displayed, and the higher the sensitivity, the higher the mountain. In the case of the example of FIG. 11, the sensitivity distribution of each surface coil 24c on the chest side of the subject P (surface coil 24c numbered 1 to 3) is displayed on the left side of the screen displayed on the display device 34. On the right side of the screen displayed on the display device 34, the sensitivity distribution of each surface coil 24c on the back side of the subject P (surface coil 24c numbered 4 to 6) is displayed. Further, for example, as shown in FIG. 12, the depth direction may be displayed in a three-dimensional display.

  The surface coil 24c displayed on the display device 34 is a combination of the surface coil 24c designated by the user in advance or a surface coil 24c capable of PI (Parallel Imaging) which is imaging using the phased array coil 24b (channel). Sensitivity distribution may be displayed for each combination.

  Thereby, the operator can know the part with high sensitivity of each surface coil 24c.

  It should be noted that, based on the sensitivity map, which surface coil 24c (channel) has the highest sensitivity at each point is obtained, and the color tone or gradation is changed in accordance with the sensitivity level and displayed in different colors. Alternatively, a portion other than the portion having the highest sensitivity of the specific surface coil 24c may be masked and displayed.

  Thereafter, the coil position display process ends.

  In the embodiment of the present invention, in the selected selection range, a dynamic scan is executed by a sequence of PI (Parallel Imaging), which is imaging using the phased array coil 24b, to generate a sensitivity map, and the generated sensitivity Based on the signal intensity in the map, a sensitivity distribution indicating a change in signal intensity in the encoding direction is generated, and the position of each surface coil 24c forming the phased array coil 24b is generated by a predetermined calculation method using the generated sensitivity distribution. (For example, the center position of each surface coil 24c, etc.) can be calculated.

  Then, according to the calculated data related to the calculated position of each surface coil 24c, the sensitivity distribution can be superimposed on the sensitivity map and displayed on the display device 34 so that the sensitivity distribution becomes a predetermined position.

  Thereby, the phased array coil 24b whose position is displayed is not limited to the surface coil 24c whose geometric position in the magnetic resonance imaging apparatus 20 is known, but the phased array coil 24b formed by the plurality of surface coils 24c. The position distribution of the phased array coil can be displayed accurately and easily.

  Therefore, the operator can easily visually determine whether the coil setting is good or bad, and at the time of PI using the phased array coil formed by many surface coils 24c, a portion where the coil sensitivity of the surface coil 24c is high can be obtained. Easy and accurate selection can be made. Further, the operator can select an appropriate coil channel combination in the phased array coil at the time of the scan plan. As a result, the S / N ratio of the NMR signal can be improved, and abnormal folding can be prevented.

  In the embodiment of the present invention, the sensitivity distribution is displayed superimposed on the sensitivity map, but the sensitivity distribution may be displayed superimposed on the G-Factor map instead of the sensitivity map. .

  The series of processes described in the embodiment of the present invention can be executed by software, but can also be executed by hardware.

  In the embodiment of the present invention, the steps of the flowchart show an example of processing that is performed in time series in the order described. However, even if they are not necessarily processed in time series, they are executed in parallel or individually. The processing to be performed is also included.

1 is a block diagram showing an internal configuration of a magnetic resonance imaging apparatus according to the present invention. The figure which shows the detailed structure of the RF coil unit of FIG. The figure which shows the example of arrangement | positioning of the surface coil of FIG. The figure which shows the other example of arrangement | positioning of the surface coil of FIG. The figure which shows the other example of arrangement | positioning of the surface coil of FIG. The figure which shows the other example of arrangement | positioning of the surface coil of FIG. The figure which shows the functional structure which the computer of the magnetic resonance imaging apparatus of FIG. 1 can perform. The flowchart explaining the coil position display process in the magnetic resonance imaging apparatus of FIG. The figure which shows the sensitivity distribution produced | generated by the sensitivity distribution production | generation part. Explanatory drawing explaining the calculation method which calculates the position of a surface coil. The figure which shows the example of a display displayed on a display apparatus. The figure which shows the other example of a display displayed on a display apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 20 ... Magnetic resonance imaging apparatus, 21 ... Magnet for static magnetic field, 22 ... Shim coil, 23 ... Gradient magnetic field coil unit, 24 ... RF coil, 24a ... WB coil, 24b ... Phased array coil, 24c ... Surface coil, 24d, 24e, 24f, 24g ... Coil unit, 25 ... Control system, 26 ... Static magnetic field power supply, 27 ... Gradient magnetic field power supply, 28 ... Shim coil power supply, 29 ... Transmitter, 30 ... Receiver, 30a ... Duplexer, 30b ... Amplifier, 30c ... Switching Synthesizer, 30d ... reception system circuit, 31 ... sequence controller, 32 ... computer, 33 ... input device, 34 ... display device, 35 ... calculation device, 36 ... storage device, 37 ... bed, 38 ... ECG unit, 41 ... sequence Controller control unit, 42 ... Sensitivity map generation unit, 43 ... Sensitivity distribution generation unit, 44 ... Coil position calculation Part, 45 ... the display control unit.

Claims (11)

Control means for controlling the execution of a dynamic scan using a phased array coil;
First generation means for generating a sensitivity map of the phased array coil when performing a dynamic scan using the phased array coil by the control means;
Second generation means for generating a sensitivity distribution indicating a change in signal intensity in the encoding direction based on a change rate of signal intensity or signal phase in the sensitivity map generated by the first generation means;
First calculation means for calculating the position of each surface coil forming the phased array coil using the sensitivity distribution generated by the second generation means;
A magnetic resonance imaging apparatus comprising: display means for superimposing and displaying the sensitivity distribution on the sensitivity map according to the position of the surface coil calculated by the first calculation means. Control means for controlling the execution of a dynamic scan using a phased array coil;
First generation means for generating a G-Factor of the phased array coil when a dynamic scan is performed using the phased array coil by the control means;
Second generation means for generating a sensitivity distribution indicating a change in sensitivity in the encoding direction based on the G-Factor generated by the first generation means;
First calculation means for calculating the position of each surface coil forming the phased array coil using the sensitivity distribution generated by the second generation means;
A magnetic resonance imaging apparatus comprising: display means for superimposing and displaying the sensitivity distribution on the G-Factor according to the position of the surface coil calculated by the first calculation means.   The magnetic resonance imaging apparatus according to claim 1, wherein the encoding direction is a phase encoding direction or a slice encoding direction.   The magnetic resonance imaging apparatus according to claim 1, wherein the display unit displays the sensitivity distribution by changing a color tone or a gradation according to a sensitivity level.   The magnetic resonance imaging apparatus according to claim 1, wherein the display unit displays the sensitivity distribution by masking a predetermined portion.   The magnetic resonance imaging apparatus according to claim 5, wherein the predetermined portion is a portion having high sensitivity in the sensitivity distribution.   The first calculation unit compares the sensitivity distribution generated by the second generation unit with a design value of the sensitivity distribution obtained in advance, and forms the phased array coil by referring to a correlation coefficient. The magnetic resonance imaging apparatus according to claim 1, wherein the position of each surface coil to be calculated is calculated.   The first calculation means compares the sensitivity distribution generated by the second generation means with a sensitivity distribution obtained in advance using a phantom, refers to a correlation coefficient, and determines the phased array coil. The magnetic resonance imaging apparatus according to claim 1, wherein the position of each surface coil to be formed is calculated.   The first calculation means corrects the sensitivity distribution generated by the second generation means based on the sensitivity distribution generated using a WB coil, and uses the corrected sensitivity distribution to correct the sensitivity distribution. The magnetic resonance imaging apparatus according to claim 1, wherein the position of each surface coil forming the phased array coil is calculated. A control step for controlling the execution of a dynamic scan using a phased array coil;
A first generation step of generating a sensitivity map of the phased array coil when performing a dynamic scan using the phased array coil by the process of the control step;
A second generation step of generating a sensitivity distribution indicating a change in the signal strength in the encoding direction based on the change rate of the signal strength or the signal phase in the sensitivity map generated by the processing of the first generation step;
A first calculation step of calculating the position of each surface coil forming the phased array coil using the sensitivity distribution generated by the processing of the second generation step;
A magnetic resonance imaging data processing method comprising: a display step of superimposing and displaying the sensitivity distribution on the sensitivity map according to the position of the surface coil calculated by the processing of the first calculation step. A control step for controlling the execution of a dynamic scan using a phased array coil;
A first generation step of generating a G-Factor of the phased array coil when performing a dynamic scan using the phased array coil by the process of the control step;
A second generation step of generating a sensitivity distribution indicating a change in sensitivity in the encoding direction based on the G-Factor generated by the processing of the first generation step;
A first calculation step of calculating the position of each surface coil forming the phased array coil using the sensitivity distribution generated by the processing of the second generation step;
A magnetic resonance imaging data processing method comprising: a display step of superimposing and displaying the sensitivity distribution on the G-Factor according to the position of the surface coil calculated by the processing of the first calculation step.

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