WO2006077715A1 - 磁気共鳴イメージング装置 - Google Patents
磁気共鳴イメージング装置 Download PDFInfo
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- WO2006077715A1 WO2006077715A1 PCT/JP2005/023646 JP2005023646W WO2006077715A1 WO 2006077715 A1 WO2006077715 A1 WO 2006077715A1 JP 2005023646 W JP2005023646 W JP 2005023646W WO 2006077715 A1 WO2006077715 A1 WO 2006077715A1
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- magnetic resonance
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- rotation
- resonance imaging
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/44—Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
- G01R33/48—NMR imaging systems
- G01R33/54—Signal processing systems, e.g. using pulse sequences ; Generation or control of pulse sequences; Operator console
- G01R33/56—Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution
- G01R33/565—Correction of image distortions, e.g. due to magnetic field inhomogeneities
- G01R33/56509—Correction of image distortions, e.g. due to magnetic field inhomogeneities due to motion, displacement or flow, e.g. gradient moment nulling
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/44—Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
- G01R33/48—NMR imaging systems
- G01R33/4818—MR characterised by data acquisition along a specific k-space trajectory or by the temporal order of k-space coverage, e.g. centric or segmented coverage of k-space
- G01R33/4824—MR characterised by data acquisition along a specific k-space trajectory or by the temporal order of k-space coverage, e.g. centric or segmented coverage of k-space using a non-Cartesian trajectory
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/44—Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
- G01R33/48—NMR imaging systems
- G01R33/54—Signal processing systems, e.g. using pulse sequences ; Generation or control of pulse sequences; Operator console
- G01R33/56—Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution
- G01R33/561—Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution by reduction of the scanning time, i.e. fast acquiring systems, e.g. using echo-planar pulse sequences
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/44—Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
- G01R33/48—NMR imaging systems
- G01R33/54—Signal processing systems, e.g. using pulse sequences ; Generation or control of pulse sequences; Operator console
- G01R33/56—Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution
- G01R33/561—Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution by reduction of the scanning time, i.e. fast acquiring systems, e.g. using echo-planar pulse sequences
- G01R33/5613—Generating steady state signals, e.g. low flip angle sequences [FLASH]
- G01R33/5614—Generating steady state signals, e.g. low flip angle sequences [FLASH] using a fully balanced steady-state free precession [bSSFP] pulse sequence, e.g. trueFISP
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/44—Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
- G01R33/48—NMR imaging systems
- G01R33/54—Signal processing systems, e.g. using pulse sequences ; Generation or control of pulse sequences; Operator console
- G01R33/56—Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution
- G01R33/561—Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution by reduction of the scanning time, i.e. fast acquiring systems, e.g. using echo-planar pulse sequences
- G01R33/5615—Echo train techniques involving acquiring plural, differently encoded, echo signals after one RF excitation, e.g. using gradient refocusing in echo planar imaging [EPI], RF refocusing in rapid acquisition with relaxation enhancement [RARE] or using both RF and gradient refocusing in gradient and spin echo imaging [GRASE]
- G01R33/5616—Echo train techniques involving acquiring plural, differently encoded, echo signals after one RF excitation, e.g. using gradient refocusing in echo planar imaging [EPI], RF refocusing in rapid acquisition with relaxation enhancement [RARE] or using both RF and gradient refocusing in gradient and spin echo imaging [GRASE] using gradient refocusing, e.g. EPI
Definitions
- the present invention relates to a magnetic resonance imaging technique.
- a nuclear magnetic resonance imaging (MRI) device is a medical device that causes nuclear magnetic resonance to occur in a hydrogen atomic nucleus in an arbitrary plane that crosses a subject, and obtains a tomographic image in that plane from the generated nuclear magnetic resonance signal.
- This is a diagnostic imaging apparatus.
- a slice gradient magnetic field that specifies a plane for obtaining a tomographic image of a subject is applied, and at the same time, an excitation pulse that excites a magnetic field in the plane is applied, and the magnetization excited thereby The nuclear magnetic resonance signal (echo) generated at the convergence stage is obtained.
- a phase encoding gradient magnetic field and a readout gradient magnetic field in a direction perpendicular to each other in the tomographic plane are applied between the excitation and the echo.
- the measured echoes are placed in k-space, where the horizontal axis is kx and the vertical axis is ky, and image reconstruction is performed by inverse Fourier transform.
- a pulse for generating an echo and each gradient magnetic field are applied based on a preset pulse sequence.
- Various pulse sequences are known depending on the purpose.
- the gradient echo (GrE) type high-speed imaging method operates by repeating the pulse sequence and sequentially changes the phase encoding gradient magnetic field for each repetition, so that the number required to obtain one tomographic image is obtained. This is a method of measuring echoes in sequence.
- Fig. 1 shows the pulse sequence of GrE-type hybrid radial scan, one of the radial scans, and Fig. 2 shows the arrangement of the measured echoes in k-space.
- a case where four blocks are set in the k space will be described as an example.
- this pulse sequence 701 is as follows. z-direction slice gradient magnetic field pulse 701-! ⁇ Application of 701-4 and gradient magnetic field pulse for dephase 702-! ⁇ 702-4 Along with proton resonance frequency f0 high frequency magnetic field (RF) magnetic field for excitation 700-! Apply ⁇ 70 0-4 to induce nuclear magnetic resonance phenomenon in protons in a slice in the target object. And for the dephase, the gradient magnetic field panorace 705—! ⁇ 705-4, 706-! ⁇ After marking 706-4, read out gradient pulse 703-! ⁇ 703-4, 704-! ⁇ While applying 704-4 nuclear magnetic resonance signal (echo) 707-! Measure 707-4.
- RF high frequency magnetic field
- Pulse sequence 701 consists of four notes 708-1, 708-2, 708-3, and 708-4, each of which has a gradient magnetic field for the dephase. Nores 705—! ⁇ 705-4 and 706-! ⁇ 706-Force of changing the size of 4 S and so on, repeated Cr times.
- the echoes 707-1, 707-2, 707-3, and 707-4 measured at each part are blocks 1, 2, 3, and, respectively, equally spaced in the ⁇ direction as shown in Fig. 2. 4, the position within each echo block is 705—! ⁇ 705-4 and 706-! ⁇ 706 — Determined by the size of 4.
- FIG. 2 the central portion of the k-space corresponding to the low frequency portion of the spatial frequency of the image is repeatedly captured.
- This region is referred to as a reference region 222.
- a method of correcting rotation and translation among the movements of the subject generated between the blocks using the reference region 222 has been proposed (for example, see Non-Patent Document 2). In this method, first, the rotation amount is detected and corrected, and then the parallel movement amount is detected and corrected.
- correlation processing is performed in the k space by using the fact that the rotation of the image space is directly the rotation of the absolute value of the k space.
- the reference area of each block is gridded on the k space, and the average is used as the standard data.
- the reference area data of each block is gridded while rotating, and the angle that maximizes the correlation value with the standard data is obtained.
- the parallel movement amount is obtained by calculating the peak position of the data obtained by Fourier transform using the average of the reference data of each block gridded after rotation correction as the reference data and the product with the reference area data of each block. Use to detect.
- Non-Patent Document 1 Jackson JI, Meyer CH, Nishimura DG: Selection of a Convolution Function for Fourier Inversion Using Gridding, IEEE Trans. Med. Imaging, Vol. 10, No • 3, pp. 473-478, 1991
- Non-Patent Document 2 J. G. Pipe: Motion Correction With PROPELLER MRI: Application to Head Motion and Free-Breathmg Cardiac Imaging, Magn. Reson. Med., Pp. 963 -969, 1999
- Non-Patent Document 3 “Echo Train Length and Number of Blades in PR 0 PELLER Method on the Effect of Motion Correction (Computer Simulation)”, Journal of Japanese Society of Radiological Technology, No. 60, No. 2, No. Pages 264-269
- An object of the present invention is to provide a magnetic resonance imaging apparatus capable of detecting and correcting body motion with high accuracy and short processing time in a radial scan.
- the present invention performs body motion detection processing in an image space.
- a template is created in which the reference data is moved in advance by a predetermined rotation amount and translation amount, and then the detection process is performed.
- the basic configuration is to do.
- A a control device that controls a pulse sequence for detecting a magnetic resonance signal generated by subject force by applying a high-frequency magnetic field and a gradient magnetic field to a subject placed in a static magnetic field; And an arithmetic unit that processes the signal, and the control unit (1) controls a pulse sequence that performs a radial scan, and (2) collects a first echo group by executing the pulse sequence. And (3) collecting the n th (n is an integer greater than or equal to 2) echo group by executing the noise sequence,
- the rotation template includes a general rotation template and a detailed rotation template having an angle difference smaller than that of the general rotation template. Consists of a general translation template and a detailed translation template having a smaller translation distance than the general translation template.
- the translation template is used, and the detailed rotation template and the detailed translation template are used in the second and subsequent processes (5) and (6).
- the invention's effect [0018] it is possible to detect body movement in a short time by using a template. Further, since the processing is performed in the image area, body movement can be detected with high accuracy even in an image with a low S / N. Noh.
- FIG. 8 is a block diagram showing a schematic configuration of a magnetic resonance merging apparatus to which the present invention is applied.
- 101 is a magnet that generates a static magnetic field
- 102 is a coil that generates a gradient magnetic field
- 103 is a subject (for example, a living body)
- the subject 103 is a static magnetic field generated by the magnet 101.
- the sequencer 104 sends commands to the gradient magnetic field power source 105 and the high frequency magnetic field generator 106 to generate a gradient magnetic field and a high frequency magnetic field, respectively.
- the high frequency magnetic field is applied to the subject 103 through the probe 107.
- a signal generated from the subject 103 is received by the probe 107 and detected by the receiver 108.
- a nuclear magnetic resonance frequency (hereinafter referred to as a detection reference frequency) as a reference for detection is set by the sequencer 104.
- the detected signal is sent to the computer 109, where signal processing such as image reconstruction is performed.
- the result is displayed on the display 110.
- the detected signal and measurement conditions can be stored in the storage medium 111 as necessary.
- the shim coil 112 When it is necessary to adjust the static magnetic field uniformity, the shim coil 112 is used.
- the shimkin 112 has a plurality of channels, and a current is supplied from the shim power supply 113.
- the current flowing in each shim coil is controlled by the sequencer 104.
- the sequencer 104 sends a command to the shim power supply 113 to generate an additional magnetic field from the coil 112 so as to correct the static magnetic field inhomogeneity.
- sequencer 104 normally performs control so that each device operates at a preprogrammed timing and intensity.
- the ones that describe the timing and intensity of the high-frequency magnetic field, gradient magnetic field, and signal reception are called pulse sequences.
- the body motion detection process is a template in which the reference image of block 1 is rotated and translated in advance.
- the matching process is a process for obtaining the smallest difference between the two images.
- Rotation of the reconstruction data and parallel movement correction processing are performed using the detected rotation 'parallel movement amount.
- the parallel movement is corrected in k space using dx and dy obtained by the body motion detection process.
- the rotation correction is performed by correcting the block angle in the gridding of the subsequent processing. Therefore, the reconstruction data corrected with translation and theta [k] are passed as input for the gridding process.
- the correction process is sequentially performed every time data of one block is measured as shown in FIG.
- Judgment as to whether or not the detection has been performed normally is made based on the fact that the minimum value of the objective function is larger than that of other blocks, and the minimum point of the objective function is within the range of the template.
- the re-measurement of blocks that have not been successfully detected is not only to collect the blocks requiring re-measurement at the end as in process (6), but also to re-measure during the measurement of block 2 to block bl. You can measure this block.
- the reference area data 805 of block 1 is reconstructed (301) to create a reference image (absolute value image) (302) (step 501).
- the number of pixels is Cr x Cr, where the number of pixels in one block is Cr.
- the reference image is preliminarily subjected to centering processing in order to improve the convergence of later rotation detection. That is, a projected image of the reference image in each of the x and y directions is created and translated so that an area equal to or greater than the maximum luminance value ⁇ (threshold) is the center of the visual field. Let this translation amount be dx [l] and dy [l]. The (threshold) depends on the image quality, but is usually around 0.4.
- a template is created using the reference image of block 1 (step 502).
- the rotation template consists of a set of images A in which the reference image is rotated with a step of rotation angle in the range of-(approximately rotation detection range) to + (approximately rotation detection range) (approximately rotation detection step), and (detailed rotation detection) This is the union of the set B of images obtained by rotating the reference image with the step of rotation angle (detailed rotation detection step) in the range of (range) to + (detailed rotation detection range).
- the rotation of the reference image is created by, for example, an interpolation image creation process described later. In Fig. 4, the rotation angle of set A is larger than that of set B.
- the approximate rotation detection range covers an expected range of the rotational movement of the subject. Set. In normal shooting, for example, the approximate rotation detection range is 16 degrees. The smaller the detailed rotation detection step, the longer the force processing time for improving the accuracy of rotation detection. Usually it is about 1 degree.
- the approximate rotation detection step is about several times the detailed rotation detection step, and is usually about 2 degrees.
- the detailed rotation detection range should be at least twice the approximate rotation detection step, usually about 8 degrees.
- the translation template has a translation step in the range of-(approximately translation detection range) to + (approximately translation detection range) as (approximately translation detection step), and the reference image is x, y Set C as the set of images translated in both directions, and the reference image as the step (detailed translation detection step) for the translation in the range from 1 (detailed translation detection range) to + (detailed translation detection range).
- This is the union of the set D of images translated in both x and y directions.
- the translation is performed by converting the reference image into k-space and changing the phase. In Fig. 4, the translation amount of set C shows a greater translation amount than set D.
- the approximate translation detection range is set to cover an expected range of translation of the subject. In normal photographing (128 pixels), for example, the approximate translation detection range is set to 6 pixels. The smaller the detailed translation detection step, the more accurate the translation detection, but the processing time becomes longer. Normally it is about 1 pixel.
- the approximate parallel movement detection step is about several times the detailed parallel movement detection step, and is usually about 3 pixels.
- the detailed translation detection range should be at least twice the approximate translation detection step, usually 2 pixels.
- a reference image of block k is created (step 504).
- the first rotation detection and parallel movement detection are performed (steps 506 and 507).
- This process is a process for detecting the rotation amount and the parallel movement amount by the matching process with the template. Detection is as follows: rotation 1st time ⁇ parallel movement 1st time ⁇ rotation 2nd time ⁇ parallel movement 2nd time ⁇ rotation 3rd time ⁇ parallel movement 3rd time and so on, rotation amount (or parallel movement amount) and previous rotation amount (Or translation amount)
- the process ends when both the out-convergence determination value and the parallel movement detection convergence determination value are satisfied (steps 508, 511, and 513), or the number of repetitions reaches the maximum value (step 515).
- the rotation detection convergence determination value and the translation detection convergence determination value are 0.05 degrees and 0.01 pixels, respectively, and the maximum number of repetitions is about 10.
- the rotation angle that minimizes the objective function is determined as the solution for each image included in the reference image of block k and the general rotation template.
- the objective function can be any function that represents the difference between the two images. For example, the square sum of the difference between two images.
- the sample points of the objective function are also discrete. Therefore, interpolation (usually a cubic function is sufficient) is used to determine the minimum value.
- FIG. 5 is an example of a graph in which the value of the objective function is plotted. From this, the minimum rotation angle can be calculated as -5.12 degrees. Let theta [k, 1] be the calculated angle.
- the original reference image is rotated by the detected rotation angle theta [k, 1]. This process is performed by an interpolation image creation process described later.
- the first translation is detected by matching with the approximate translation template (step 507).
- the objective function is two-dimensional. Therefore, two-dimensional interpolation is also used to determine the minimum value. A cubic function is usually sufficient as the interpolation order.
- FIG. 6 is an example of a graph displaying the value of the objective function as a grayscale image. From this, the minimum translation amount is calculated as (1.43, 0.27) pixels. Let the calculated amount of translation be (dx [k, 2 dy, dy [k, 2]).
- the original reference image is moved by the rotation amount and the parallel movement amount detected so far. This process is performed by an interpolation image creation process described later.
- a convergence determination is made between rotation detection and parallel movement detection (step 508). Convergence judgment is made when the previous rotational movement amount or parallel movement amount has become smaller than a predesignated value (convergence judgment value), and jumps to step 516. For example, if the convergence judgment value is 0.01 pixel for parallel movement and 0.05 degree for rotational movement, sufficient detection accuracy can be obtained. [0045] If the convergence is not determined in the convergence determination (step 508), the second and subsequent rotation detection and parallel movement detection are continued.
- the number of body motion detections kk is set to 2 (step 509).
- rotation detection and rotation are performed as in step 506 (step 510).
- convergence determination is performed in the same manner as in step 508 (step 511). If converged, the process jumps to step 516. Otherwise, the same translation detection and translation as in step 507 are performed (step 512).
- convergence determination is performed in the same manner as in step 508 (step 513). If the convergence has occurred, the process jumps to step 516. Otherwise, kk is increased by 1 (step 514).
- nk is the maximum number of body motion detection specified in advance, and if it is usually set to about 10, sufficient detection accuracy can be obtained. Even if this value is set to about 10 or more, the detection accuracy is rarely improved only by extending the calculation time in normal imaging.
- step 516 the rotation amount and the translation amount are calculated (step 516), k is increased by 1 (step 517), and step 504 force is processed until all blocks are processed. Repeat 517 (step 518).
- body motion can be detected in a short time, and an image free from artifacts can be reconstructed.
- body motion can be detected accurately even in low S / N images.
- An example of such a case is brain function imaging.
- functional brain imaging for example, images are taken continuously for 5 minutes at 1-second intervals to reconstruct a total of 300 images.
- the subject repeats an idle state (rest state) and an activity state (task state) such as moving fingers every minute.
- the average of the images taken in the first resting state after taking the image is also subtracted from the subsequent image power, and the brain active area is extracted by statistical processing. If the subject moves during imaging, there will be a gap between the images, and it will not be possible to match the parts when taking the difference between the images, so all images must be in the same position.
- the method of the present embodiment is applied: !!
- the power of the image that can be corrected is corrected at different positions between the images. Therefore, in order to eliminate misalignment between images, body motion detection and correction for each block of all images is performed using a template created from one block.
- rephase gradient magnetic fields 209, 210, and 211 are applied to return the magnetization phase and prepare for the next excitation.
- the above procedure is repeated Ne times with the repetition time TR, and Ne echoes are measured.
- the echo is placed in k-space.
- Dephase gradient magnetic field pulse 204 and rephase gradient magnetic field pulse 209 are from _Ne / 2 to Ne / 2_1, and dephase gradient magnetic field pulse 205 and rephase gradient magnetic field pulse 2 09 are from 0 through _Ne / 2.
- the readout gradient magnetic field pulse 206 changes from Ne / 2 to -Ne / 2-l
- the readout gradient magnetic field pulse 207 changes from 0 to 1 through Ne / 2.
- the order of change is such that echoes are placed in four blocks (117-1 to 117-4) in k-space.
- Fig. 10 shows the k-space at this time.
- the echo arrangement of each block is as follows: echo rotation angle 802 force 3 ⁇ 4 X 180 / Ne degree, rotation angle offset 118-1 ⁇ : 118-4 force 0 degree (Fig. 10 (a)), 180 / Ne degree ( Fig. 10 (b)), 2 X 180 / Ne degrees (Fig. 10 (c)), and 3 X 180 / Ne degrees (Fig. 10 (d)).
- the reference area is 115 circular areas as shown in the figure.
- the reference image is created by gridding the data in this area.
- the reference image matrix size is Cr X.
- Cr is small and the accuracy of motion detection is low, the accuracy may improve if the number of pixels is about 32 X 32 by zero fill after gridding.
- the reference image is preliminarily centered in order to improve the convergence of later rotation detection.
- a projected image of the reference image in the x and y directions is created, and the reference image is translated so that an area equal to or greater than the maximum luminance value x (threshold value) becomes the center of the visual field.
- x (threshold) is a power that depends on image quality, usually about 0.4.
- Subsequent body motion detection and correction processing is the same as in the case of No, Ivliz radial.
- the corrected data is arranged in k-space 116 and reconstructed by gridding as shown in Fig. 10 (e).
- body movement can be detected and corrected even in a radial scan, and an image with no displacement or artifact can be obtained.
- the magnetic resonance imaging technique according to the present invention can detect a body motion in a short time by using a template, and since it is processed in an image region, it can be accurately performed even in a low S / N image. Body movement can be detected. Therefore, it can be said that the medical and industrial significance of the present invention is great.
- FIG. 1 is a diagram for explaining a pulse sequence of a conventional GrE hybrid radial scan.
- FIG. 2 is a diagram for explaining the k-space of a conventional GrE hybrid radial scan.
- FIG. 3 is a diagram showing a flowchart for body movement detection in one embodiment of the present invention.
- FIG. 4 is a diagram for explaining a template in one embodiment of the present invention.
- FIG. 5 is a diagram showing a change in an objective function when rotation is detected in one embodiment of the present invention.
- FIG. 6 is a diagram showing a change in an objective function when a parallel movement is detected in one embodiment of the present invention.
- FIG. 7 is a diagram for explaining the timing of measurement and processing in one embodiment of the present invention.
- FIG. 8 is a diagram showing a configuration example of a nuclear magnetic resonance imaging apparatus to which the present invention is applied.
- FIG. 9 is a diagram illustrating a GrE radial scan pulse sequence according to an embodiment of the present invention.
- FIG. 10 is a diagram illustrating a radial scan block according to an embodiment of the present invention.
- 101 Magnet that generates a static magnetic field
- 102 Gradient magnetic field coil
- 103 Subject
- 104 Sequencer
- 105 Gradient magnetic field power supply
- 106 High frequency magnetic field generator
- 107 ... Probe
- 108 ... Receiver
- 109 ... Computer
- 110 ... Display
- 111 Storage medium
- 112 Simcoinore
- 113 ... Sim power supply
- 115 ... Reference region, 116 "'space, 201 ... slice gradient magnetic field, 202 ... high frequency magnetic field (RF) pulse for magnetization excitation, 203-205 ... gradient gradient magnetic field for dephase.
- RF magnetic field
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WO2012043311A1 (ja) * | 2010-09-27 | 2012-04-05 | 株式会社 日立メディコ | 磁気共鳴イメージング装置および磁気共鳴イメージング方法 |
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JP2016536045A (ja) * | 2013-10-08 | 2016-11-24 | コーニンクレッカ フィリップス エヌ ヴェKoninklijke Philips N.V. | 補正マルチスライス磁気共鳴イメージング |
JP2015160140A (ja) * | 2014-02-27 | 2015-09-07 | 株式会社東芝 | 磁気共鳴イメージング装置、磁気共鳴イメージング方法及び磁気共鳴イメージングプログラム |
Also Published As
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JP4612000B2 (ja) | 2011-01-12 |
JPWO2006077715A1 (ja) | 2008-06-19 |
US7622926B2 (en) | 2009-11-24 |
US20080169808A1 (en) | 2008-07-17 |
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