WO2014196525A1 - 計測装置及び計測方法 - Google Patents
計測装置及び計測方法 Download PDFInfo
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- WO2014196525A1 WO2014196525A1 PCT/JP2014/064725 JP2014064725W WO2014196525A1 WO 2014196525 A1 WO2014196525 A1 WO 2014196525A1 JP 2014064725 W JP2014064725 W JP 2014064725W WO 2014196525 A1 WO2014196525 A1 WO 2014196525A1
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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
- G01R33/563—Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution of moving material, e.g. flow contrast angiography
- G01R33/56375—Intentional motion of the sample during MR, e.g. moving table imaging
- G01R33/56383—Intentional motion of the sample during MR, e.g. moving table imaging involving motion of the sample as a whole, e.g. multistation MR or MR with continuous table motion
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/70—Means for positioning the patient in relation to the detecting, measuring or recording means
- A61B5/704—Tables
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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
- G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
- G01R33/32—Excitation or detection systems, e.g. using radio frequency signals
- G01R33/34—Constructional details, e.g. resonators, specially adapted to MR
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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
- G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
- G01R33/38—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field
- G01R33/385—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field using gradient magnetic field coils
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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
- G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
- G01R33/38—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field
- G01R33/385—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field using gradient magnetic field coils
- G01R33/3858—Manufacture and installation of gradient coils, means for providing mechanical support to parts of the gradient-coil assembly
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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
- G01R33/62—Arrangements or instruments for measuring magnetic variables involving magnetic resonance using double resonance
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/05—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves
- A61B5/055—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
Definitions
- the present invention relates to a measurement apparatus and a measurement method for acquiring a nuclear magnetic resonance (NMR) signal or further acquiring a magnetic resonance imaging (MRI) image.
- NMR nuclear magnetic resonance
- MRI magnetic resonance imaging
- a magnetic resonance imaging apparatus (hereinafter referred to as an MRI apparatus) measures nuclear spin density distribution, relaxation time distribution, etc. in a subject using a nuclear magnetic resonance phenomenon, and based on the measurement data, obtains an image of a cross section of the subject.
- a device that generates and displays.
- the nuclear spin contained in a subject precesses around the direction of the main magnetic field at a frequency (Larmor frequency) determined by the strength of the main magnetic field in a uniform static magnetic field (main magnetic field).
- Larmor frequency a frequency determined by the strength of the main magnetic field in a uniform static magnetic field (main magnetic field).
- RF pulse high-frequency electromagnetic wave
- the nuclear spin is excited and transitions to a high energy state (nuclear magnetic resonance phenomenon).
- the nuclear spin returns to the original low energy state with a time constant corresponding to each state.
- a nuclear magnetic resonance signal is emitted from the nucleus.
- This NMR signal is received by a high-frequency receiving coil tuned to that frequency. This NMR signal is also called an echo signal.
- a triaxial gradient magnetic field is applied to the main magnetic field space.
- the application of the gradient magnetic field is performed for the purpose of adding position information to the detected NMR signal, and the direction of the gradient corresponds to the slice direction, the encode direction, and the readout direction.
- the MRI apparatus can generate a two-dimensional image inside the subject by performing two-dimensional Fourier analysis on the received echo signal sequence.
- Non-Patent Document 1 discloses a technique for moving a subject that is moving by a technique called TimCT (Continuous Table Move). An example of acquiring an MRI image of a specimen is shown. According to the TimCT technology, it is possible to obtain an MRI image of the whole body from the head to the foot of the subject such as a patient by continuously moving the table on which the subject is placed in the main magnetic field of the MRI apparatus. It can be done.
- TimCT Continuous Table Move
- Patent Document 1 shows an example of a fusion MRI apparatus characterized by acquiring an ESR (Electron Spin Resonance) / NMR fusion image of a subject.
- the fusion MRI apparatus includes a first magnet that forms a static magnetic field for ESR, a second magnet that forms a static magnetic field for NMR, and the static magnetic field for ESR described above.
- a moving means for moving the subject between the static magnetic field for NMR is provided. Then, after exciting the electron spin contained in the subject in the static magnetic field for ESR, the subject is moved into the static magnetic field for NMR, and the MRI image is acquired.
- the magnitude of the electron spin excited by the static magnetic field for ESR can be measured as an NMR signal greatly amplified by the so-called Overhauser effect in the static magnetic field for NMR. Therefore, by subtracting the MRI image of the subject generated based on the normal NMR signal with only the static magnetic field for NMR from the MRI image of the subject generated based on the NMR signal thus obtained, high sensitivity, High resolution electron spin magnetic resonance images (ESRI) can be obtained.
- ESRI electron spin magnetic resonance images
- an ESR / NMR fused image generated by superimposing this ESRI image on a normal MRI-based MRI image is displayed, the electron spin intensity distribution is visualized in the morphological image of the subject.
- a fusion MRI apparatus Since many of electron spins are derived from unpaired electrons of free radicals such as active oxygen in living organisms, such a fusion MRI apparatus has many physiological phenomena and disease causes. It has an excellent effect in visualizing the state of redox metabolism including free radicals that are closely involved.
- Such a fusion MRI apparatus is called an OMRI (Overhauser effect MRI) apparatus, a PEDRI (Proton Electron Double Resonance Imaging) apparatus, a ReMI (Redox Molecular Imaging) apparatus, or the like.
- the moving means on which the subject is mounted is an ESR so that the time transition of the electron spin intensity distribution (ie, the distribution of free radicals) can be easily acquired. It can be repeatedly moved between a static magnetic field for NMR and a static magnetic field for NMR.
- a large acceleration is generated when the moving means is moved or stopped. At this time, a large load is applied to the living body of the subject.
- a subject is stopped by rotating a first magnet that forms a static magnetic field for ESR and a second magnet that forms a static magnetic field for NMR along a predetermined circular orbit.
- An example of a fusion MRI apparatus is disclosed that is configured so that a subject can repeatedly pass (relatively pass) through a static magnetic field for ESR and a static magnetic field for NMR in an as-is state.
- the NMR signal is measured in a state where the subject is stopped, so that the load problem such as acceleration applied to the subject such as a living body is solved.
- an MRI image of the whole body of a person can be obtained by passing the main magnetic field through a table on which the subject is mounted.
- This is an example of successful imaging of a moving subject, which is impossible with a normal MRI apparatus.
- the moving speed for moving the table that is, the subject is slow (this moving speed is about several centimeters / second and is sufficiently slow compared with the NMR signal detection time). There was a limit to improvement.
- the magnetic field gradient coil is composed of at least three independent coils, and each coil forms a gradient magnetic field in three axial directions of x, y, and z.
- the three independent coils require at least six power cables for supplying power.
- the magnetic field gradient coil is fixed to a second magnet that forms a static magnetic field for NMR, and repeatedly rotates in the same direction together with the second magnet. Therefore, if the power cable is simply connected to the magnetic field gradient coil, the power cable is twisted with the rotation of the magnetic field gradient coil.
- various devices are required for the connecting power feeding unit to the magnetic field gradient coil, and as a result, the configuration of the connecting power feeding unit is complicated.
- the present invention can acquire a good MRI image even when a subject or a magnet forming a main magnetic field (static magnetic field) is moved at a high speed, and the connection power feeding unit to the magnetic field gradient coil can be configured with a simple configuration.
- An object of the present invention is to provide a measurement apparatus and a measurement method that can be completed and that can be easily adjusted for MRI imaging.
- the object of the invention described above is basically achieved by making the magnetic field gradient coil relatively movable with respect to the magnet forming the static magnetic field (main magnetic field) for NMR. That is, the measuring device according to the present invention is disposed so as to be relatively movable with respect to a magnet that forms a static magnetic field in a predetermined region space and the magnet that forms the static magnetic field, and applies a gradient magnetic field to the static magnetic field.
- a magnetic field gradient coil that radiates a high-frequency signal that excites a nuclear spin contained in the subject, and a resonance coil that receives a nuclear magnetic resonance signal generated by the nuclear spin.
- the measurement apparatus irradiates the subject with the high-frequency signal through the resonance coil while the magnetic field gradient coil is relatively moving in the region space where the static magnetic field is formed, and the nucleus.
- the magnetic resonance signal is received and acquired, or a magnetic resonance image of the subject is acquired based on the acquired nuclear magnetic resonance signal.
- an MRI image can be acquired even when a subject or a magnet that forms a main magnetic field (static magnetic field) is moved at high speed, and a connection power feeding unit to a magnetic field gradient coil can be simply configured.
- a connection power feeding unit to a magnetic field gradient coil can be simply configured.
- adjustment for MRI imaging is facilitated.
- mold MRI apparatus which concerns on the 2nd Embodiment of this invention The figure which showed the example of the cross-section from the side of the ESR / NMR fusion type
- FIG. 1 is a diagram schematically showing an example of a cross-sectional structure from the side of the MRI apparatus 100 for whole body imaging of a subject according to the first embodiment of the present invention
- FIG. 2 is a front view of the MRI apparatus 100
- FIG. 3 is a diagram illustrating an example of a cross-sectional structure of FIG. 3
- FIG. 3 is a diagram illustrating an example of a top view of the MRI apparatus 100.
- the MRI apparatus 100 for subject whole-body imaging is a so-called open type MRI apparatus. Accordingly, the main magnetic field for NMR is formed in a space sandwiched between two magnets 11 that are spaced apart from each other and disposed substantially horizontally. Then, the subject 16 as the subject is inserted into the space where the main magnetic field is formed while being placed on the table 15.
- the size of the main magnetic field space formed by the upper and lower two magnets 11 is sufficiently large to accommodate the entire table 15 and the subject 16.
- the subject 16 is inserted into the main magnetic field space so that the body axis direction is along the longitudinal direction of the upper and lower two magnets 11.
- one magnetic field gradient coil 13 is provided between each of the upper and lower two magnets 11 and the subject 16.
- the two upper and lower magnetic field gradient coils 13 are fixedly connected to each other and configured to be movable back and forth along the longitudinal direction of the magnet 11 (the body axis direction of the subject 16).
- the x direction, y direction, or A gradient magnetic field in the z direction is formed.
- a mechanism for moving the upper and lower magnetic field gradient coils 13 along the longitudinal direction of the magnet 16 is, for example, as shown in FIGS. 2 and 3 on the floors on both sides of the lower magnet 11. This can be realized by two carriages 18 traveling on two tracks 19 provided along the longitudinal direction. In this case, the upper and lower two magnetic field gradient coils 13 are firmly supported by the two carriages 18 and move back and forth as the two carriages 18 travel.
- a high-frequency signal (electromagnetic wave) that excites a nuclear spin contained in the subject (subject 16) is generated, and a resonance signal (magnetic) due to the nuclear spin is generated.
- a resonance coil for receiving (resonance signal: NMR signal) is fixedly attached to the magnetic field gradient coil 13. That is, a resonance coil (not shown) moves together with the magnetic field gradient coil 13.
- the MRI apparatus 100 has a control device (not shown).
- the control device controls the movement of the carriage 18, that is, the magnetic field gradient coil 13, controls the current to flow through the magnetic field gradient coil 13, forms a gradient magnetic field, and resonates.
- a high-frequency signal is output from a coil (not shown), and control for receiving an NMR signal is executed.
- the control device first drives the carriage 18 and moves the magnetic field gradient coil 13 to one end of the main magnetic field space sandwiched between the upper and lower two magnets 11 (for example, at the end on the head side of the subject 16).
- the control device commands the carriage 18 to travel at a constant speed to the other end of the main magnetic field, and based on a predetermined imaging sequence for the magnetic field gradient coil 13 and the resonance coil. It repeatedly commands the generation of high-frequency signals, the generation of gradient magnetic fields, and the reception of NMR signals.
- control device repeatedly performs a predetermined imaging sequence while moving the magnetic field gradient coil 13 and the resonance coil in a uniform main magnetic field. Therefore, the control device can acquire the MRI image of the subject 16 sliced in the vicinity of the center position of the magnetic field gradient coil 13 every time the imaging sequence is executed.
- the magnetic field gradient coil is integrally formed with the magnet that forms the main magnetic field, and the magnetic field gradient coil is structurally separated from the magnet that forms the main magnetic field.
- a structure that moves independently is not assumed. This is because the magnetic field gradient coil plays a role of improving the uniformity of the magnetic field called shim adjustment.
- shim adjustment plays a role of improving the uniformity of the magnetic field.
- the magnetic field gradient coil moves relative to the magnet that forms the main magnetic field, even if shim adjustment is performed at a certain relative position to improve the uniformity of the magnetic field, if the relative position changes, the adjustment becomes invalid and readjustment is possible. It is necessary.
- Faraday's law of electromagnetic induction an induced current is generated when the magnetic flux passing through the gradient coil changes, and the induced current becomes a noise source.
- the gradient coil 13 is a separate structure from the magnet 11 that forms the main magnetic field, and moves back and forth along the longitudinal direction of the magnet 11. It is possible. That is, the MRI apparatus 100 according to the present embodiment has a structure in which the magnet 11 and the subject 16 are stationary and the gradient magnetic field coil 13 is moved instead, so that the subject 16 moves substantially (that is, moves relatively). It is possible to acquire MRI images of the whole body. In a preliminary experiment by the inventors of the present invention, an MRI image that is good enough to withstand practical use is obtained even when the gradient magnetic field coil 13 is moved at high speed.
- the MRI image when the subject 16 is substantially moved at high speed can be obtained by moving the gradient magnetic field coil 13 at a high speed, the problem of the acceleration received by the subject 16 does not occur. . Furthermore, in this embodiment, since the gradient magnetic field coil 13 does not rotate, the problem that the power cable connected to the gradient magnetic field coil 13 twists does not arise.
- the imaging parameters from the nuclear spin excitation to the NMR signal reception are adjusted so that the signal acquisition time at one time is several tens of milliseconds or less. Therefore, even if the gradient magnetic field coil 13 is moved at a very high speed of about several meters per second, for example, NMR signals can be acquired and an MRI image that can be practically used can be obtained.
- the gradient magnetic field coil 13 that defines the center position of the FOV can be matched with the center of the position of the subject to be imaged, it is possible to image the area to be imaged at the center of the FOV with high sensitivity.
- FIG. 4 schematically shows an example of a perspective view of an ESR / NMR fusion MRI apparatus 200 according to the second embodiment of the present invention
- FIG. 5 shows an upper surface of the ESR / NMR fusion MRI apparatus 200
- FIG. 6 is a diagram showing an example of a cross-sectional structure from the side of the ESR / NMR fusion MRI apparatus 200
- FIG. 7 is a diagram showing an example of the ESR / NMR fusion MRI apparatus 200. It is the figure which showed the example of the position which arrange
- the ESR / NMR fusion MRI apparatus 200 is assumed to be used for research of redox metabolism including active oxygen and free radicals (free radicals) in a small animal or a part of a human body.
- the first magnet 21 separated into the upper and lower parts and the upper and lower parts are similarly separated into the upper and lower parts.
- the second magnet 22 is disposed on an upper portion of a cylindrical base 30 having a substantially horizontal upper surface.
- Each of the first magnet 21 and the second magnet 22 each having two upper and lower portions is provided with a support member (not shown) on a rotating column 32 disposed coaxially with the central axis of the columnar base 30. It is attached integrally through. Therefore, when the rotating column 32 rotates, the first magnet 21 and the second magnet 22 rotate together with the rotating column 32. Therefore, when a point included on the first magnet 21 and the second magnet 22 is projected onto the upper surface of the base 30, the projected point draws a circular locus.
- a static magnetic field (main magnetic field) for NMR of 0.3 T (Tesla) is formed in the space between the two first magnets 21, and the two second magnets
- a static magnetic field for ESR of 0.013 T is formed in the space between 22.
- the planar shape of the second magnet 22 is a “C” shape having a width in order to secure a time for sufficiently exciting the electron spin.
- the vertical distance between the two first magnets 21 is substantially the same as the vertical distance between the two second magnets 22.
- the subject 26 is inserted in a state of being placed on the table 25 in a space sandwiched between the two first magnets 21 (or a space sandwiched between the two second magnets 22).
- Magnetic field gradient coils 23 are respectively disposed between the magnets 22).
- the table 25 on which the subject 26 is placed is supported by a support base 33, and the support base 33 is near the floor on which the base 30 is installed. Is installed.
- the two upper and lower magnetic field gradient coils 23 are firmly connected to each other by a connecting member 29 (see FIG. 7), and are fixed to a part of the table 25 or the upper surface of the base 30 (not shown).
- the subject 26 and the magnetic field gradient coil 23 remain stationary. That is, in this embodiment, when the rotating column 32 rotates, the space in which the static magnetic field for NMR is formed and the space in which the static magnetic field for ESR is formed cross the subject 26 and the magnetic field gradient coil 23 alternately. become. Conversely, the subject 26 and the magnetic field gradient coil 23 move (relatively move) one after another in the space where the static magnetic field for NMR is formed and the space where the static magnetic field for ESR is formed. .
- the NMR resonance coil 27 and the ESR resonance coil 28 are fixed to the magnetic field gradient coil 23 or the connecting member 29. Therefore, the NMR resonance coil 27 and the ESR resonance coil 28 are rotated. Even if the pillar 32 rotates, it is stationary.
- the resonance frequency of the resonance coil 28 for ESR is 370 MHz when the static magnetic field for ESR is about 0.013 T
- the resonance frequency of the resonance coil 27 for NMR is 0.3 T for the static magnetic field for NMR. When it is about, it is about 12 MHz.
- the table 25 on which the subject 26 is placed is supported by the support base 33 so as to be movable in the diameter direction of the base 30. Therefore, the user can place the subject 26 on the table 25 in a state where the table 25 is pulled out from the space sandwiched between the first magnet 21 or the second magnet 22. The placed subject 26 can be inserted into a space sandwiched between the first magnet 21 or the second magnet 22.
- the ESR / NMR fusion MRI apparatus 200 configured as described above is used as the OMRI (overhauser effect MRI) apparatus described above.
- OMRI overhauser effect MRI
- the electron spin of unpaired electrons contained in the subject 26 moves while the subject 26 is relatively moving in the static magnetic field for ESR formed by the second magnet 22. Excited by a high frequency signal (electromagnetic wave) irradiated from. At this time, the nuclear spin including the unpaired electron is excited by the Overhauser effect.
- a high-frequency signal electromagnet resonance
- the specimen 26 is irradiated, nuclear spins are excited, a gradient magnetic field is appropriately applied by the magnetic field gradient coil 23, and an NMR signal from the subject 26 is received by the NMR resonance coil 27.
- the NMR signal received in this way includes a resonance signal from a nuclear spin excited by the Overhauser effect. Therefore, the MRI image generated from the NMR signal includes nuclear spins excited by the Overhauser effect, that is, distribution information of electron spins of unpaired electrons. That is, an OMRI image is obtained.
- the ESR / NMR fusion MRI apparatus 200 has a control device (not shown) as in the case of the first embodiment. Then, the control device controls the rotation of the rotating column 32, that is, the first magnet 21 and the second magnet 22, detects the rotational position of the first magnet 21, and sends a current to the magnetic field gradient coil 13 to tilt the magnetic field gradient coil 13. Control for forming a magnetic field, detection of the rotational position of the first magnet 21 or the second magnet, output of a high frequency signal from the NMR resonance coil 27 or ESR resonance coil 28, and control for receiving an NMR signal, etc. .
- the ESR / NMR fusion MRI apparatus 200 can also be used as a normal MRI apparatus. In that case, it is only necessary to stop the rotation of the first magnet 21 and the second magnet 22 in a state where the subject 26 is positioned at the approximate center of the static magnetic field for NMR formed by the first magnet 21. Good. At this time, an MRI image in a state of being stationary with respect to the first magnet 21 of the subject 26 can be obtained.
- a normal MRI image can be obtained even when the first magnet 21 and the second magnet 22 are rotating. That is, if the high frequency signal is not irradiated from the ESR resonance coil 28 when the subject 26 is relatively moving in the ESR static magnetic field formed by the second magnet 22, the Overhauser effect is obtained. Since this does not occur, a normal MRI image can be obtained while the subject 26 is relatively moving in the static magnetic field for NMR formed by the first magnet 21.
- an MRI image (OMRI image) of the subject 26 including electron spin distribution information of unpaired electrons and an MRI image of the normal subject 26 are taken.
- an MRI image of the subject 26 including electron spin distribution information of unpaired electrons can be obtained.
- an image obtained by superimposing the MRI image (ESRI image) of the subject 26 including only the distribution information of the electron spins of unpaired electrons obtained as described above on the normal MRI image of the same subject 26 is displayed.
- the distribution information of electron spins of unpaired electrons is displayed on a normal MRI image that is also a morphological image of the subject 26.
- the electron spin distribution information of the unpaired electrons can be continuously obtained. It is possible to visualize the time transition of the spin distribution. Since the time transition of the electron spin distribution of the unpaired electrons can be said to represent the dynamics of active oxygen and free radicals (free radicals), this deepens the understanding of the redox reaction.
- the ESR / NMR fusion MRI apparatus 200 has almost the same function as the OMRI (fusion MRI) disclosed in Patent Document 2.
- the magnetic field gradient coil 23 since the magnetic field gradient coil 23 has a separate structure separated from the first magnet 21, even if the first magnet 21 and the second magnet 22 rotate due to the rotation of the rotating column 32.
- the magnetic field gradient coil 23 does not rotate and is stationary with the subject 26.
- the connection power supply unit of the power cable to the magnetic field gradient coil 23 can be simply configured. That is, according to the present embodiment, the problem that occurs in OMRI disclosed in Patent Document 2 is solved.
- the separate structure in which the magnetic field gradient coil 23 is separated from the first magnet 21 cannot be derived from the conventional common sense. This is because, as described above, it seems difficult to ensure the uniformity of the static magnetic field for NMR formed by the first magnet 21.
- the inventors of the present invention made a prototype of a separate structure in which the magnetic field gradient coil 23 was separated from the first magnet 21 without being caught by the above-mentioned common sense idea. Good tolerable MRI and OMRI images were obtained.
- the relative speed with respect to the stationary subject 26 when the first magnet 21 rotates is 1 to 2 m / sec. This is because redox metabolism research requires obtaining time-sequential images of the electron spin intensity distribution (ie, the distribution of active oxygen and free radicals) at as short an interval as possible (for example, at intervals of 1 to 2 seconds). Because it is.
- the relative speed with respect to the subject 26 when the first magnet 21 rotates is 1 to 2 m / second, and the length of the uniform region of the static magnetic field for NMR formed by the first magnet 21 is 10 cm.
- the imaging sequence from nuclear spin excitation to MRI signal acquisition must be completed within tens of milliseconds.
- the imaging sequence takes too much time in the conventional spin echo method or gradient echo method, and the subject 26 comes out of the uniform region of the static magnetic field for NMR before the imaging sequence is completed.
- FIG. 8 is a diagram showing an MRI image acquired by the ESR / NMR fusion MRI apparatus 200 according to the second embodiment of the present invention compared with an MRI image acquired by a conventional MRI apparatus.
- the image on the left is a picture of a pig foot used as the subject 26.
- the central image is an MRI image of a pig foot acquired by a general MRI apparatus having a static magnetic field for NMR of 1.5T.
- the right image is obtained by the ESR / NMR fusion MRI apparatus 200 according to the present embodiment (the intensity of the static magnetic field for NMR: 0.3 T, the relative movement speed of the subject 26 and the magnetic field gradient coil 23: 1 m / second). It is the acquired MRI image of a pig leg.
- the ESR / NMR fusion MRI apparatus 200 can obtain an MRI image that is generally good enough to withstand practical use.
- the subject can be imaged at the center of the FOV without particularly adjusting the imaging timing.
- the ESR / NMR fusion MRI apparatus 200 does not acquire the MRI image or the OMRI image of the subject 26, the DNP (Dynamic It is clear that it can be used as a measuring device for acquiring and analyzing NMR signals including the “Nuclear-Polarization” effect.
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Abstract
Description
図1は、本発明の第1の実施形態に係る被験者全身撮像用のMRI装置100の側方からの断面構造の例を模式的に示した図、図2は、同MRI装置100の前方からの断面構造の例を示した図、図3は、同MRI装置100の上面図の例を示した図である。
図4は、本発明の第2の実施形態に係るESR/NMR融合型MRI装置200の斜視図の例を模式的に示した図、図5は、同ESR/NMR融合型MRI装置200の上面図の例を示した図、図6は、同ESR/NMR融合型MRI装置200の側方からの断面構造の例を示した図、図7は、同ESR/NMR融合型MRI装置200において、磁場勾配コイルを配置する位置の例を示した図である。なお、このESR/NMR融合型MRI装置200は、小動物や人体の一部などにおける活性酸素や遊離基(フリーラジカル)を含むレドックス代謝の研究用に用いられることを想定している。
13 磁場勾配コイル
15 テーブル
16 被験者(被検体)
18 台車
19 軌道
100 MRI装置
200 ESR/NMR融合型MRI装置(MRI装置)
21 第1の磁石
22 第2の磁石
23 磁場勾配コイル
25 テーブル
26 被検体
27 NMR用共振コイル
28 ESR用共振コイル
29 連結部材
30 基台
32 回転柱
33 支持台
100 MRI装置
200 ESR/NMR融合型MRI装置
Claims (11)
- 所定の領域空間に静磁場を形成する磁石と、
前記静磁場を形成する磁石に対して相対移動可能に配設されて、前記静磁場に傾斜磁場を付与する磁場勾配コイルと、
被検体に含まれる原子核スピンを励起させる高周波信号を照射するとともに、前記原子核スピンによる核磁気共鳴信号を受信する共振コイルと、
を備えること
を特徴とする計測装置。 - 請求項1に記載の計測装置において、
前記静磁場が形成された領域空間を前記磁場勾配コイルが相対移動している間に、前記共振コイルを介して前記被検体に前記高周波信号を照射するとともに、前記核磁気共鳴信号を受信し、取得すること
を特徴とする計測装置。 - 請求項2に記載の計測装置において、
前記取得した核磁気共鳴信号に基づき、さらに、前記被検体の磁気共鳴画像を生成すること
を特徴とする計測装置。 - 請求項1に記載の計測装置において、
前記静磁場が形成された領域空間に近隣する第2の領域空間に前記静磁場と異なる第2の静磁場を形成する第2の磁石をさらに備え、
前記磁場勾配コイルは、前記磁石及び前記第2の磁石の両方に対して相対移動可能に配設され、
前記第2の静磁場が形成された第2の領域空間を前記磁場勾配コイルが相対移動している間に、前記共振コイルを介して前記被検体に含まれる電子スピンを励起する高周波信号を照射し、
前記静磁場が形成された領域空間を前記磁場勾配コイルが相対移動している間に、前記共振コイルを介して前記被検体に含まれる原子核スピンを励起する高周波信号を前記被検体に照射するとともに、前記核磁気共鳴信号を受信し、取得すること
を特徴とする計測装置。 - 請求項4に記載の計測装置において、
前記取得した核磁気共鳴信号に基づき、さらに、前記被検体の磁気共鳴画像を生成すること
を特徴とする計測装置。 - 請求項4に記載の計測装置において、
前記磁場勾配コイルは、円柱状の基台に固定して配設され、
前記磁石及び前記第2の磁石は、前記円柱状の基台の円形上面の周縁部に沿って回動可能に配設され、
前記磁場勾配コイルは、前記磁石及び前記第2の磁石が前記円柱状の基台の円形上面の周縁部に沿って回動するとき、前記磁石及び前記第2の磁石それぞれによってそれぞれ形成される前記静磁場及び前記第2の静磁場の中を相対的に移動すること
を特徴とする計測装置。 - 所定の領域空間に静磁場を形成する磁石と、
前記静磁場を形成する磁石に対して相対移動可能に配設されて、前記静磁場に傾斜磁場を付与する磁場勾配コイルと、
被検体に含まれる原子核スピンを励起させる高周波信号を照射するとともに、前記原子核スピンによる核磁気共鳴信号を受信する共振コイルと、
を少なくとも備えた計測装置によって行われる計測方法において、
前記計測装置は、
前記静磁場が形成された領域空間を前記磁場勾配コイルが相対移動している間に、前記共振コイルを介して前記被検体に前記高周波信号を照射するとともに、前記核磁気共鳴信号を受信し、取得すること
を特徴とする計測方法。 - 請求項7に記載の計測方法において、
前記計測装置は、前記取得した核磁気共鳴信号に基づき、さらに、前記被検体の磁気共鳴画像を生成すること
を特徴とする計測方法。 - 請求項7に記載の計測方法において、
前記計測装置は、前記静磁場が形成された領域空間に近隣する第2の領域空間に前記静磁場と異なる第2の静磁場を形成する第2の磁石をさらに備え、
前記磁場勾配コイルは、前記磁石及び前記第2の磁石の両方に対して相対移動可能に配設され、
前記計測装置は、
前記第2の静磁場が形成された第2の領域空間を前記磁場勾配コイルが相対移動している間に、前記共振コイルを介して前記被検体に含まれる電子スピンを励起する高周波信号を前記被検体に照射し、
前記静磁場が形成された領域空間を前記磁場勾配コイルが相対移動している間に、前記共振コイルを介して前記被検体に含まれる原子核スピンを励起する高周波信号を前記被検体に照射するとともに、前記核磁気共鳴信号を受信し、取得すること
を特徴とする計測方法。 - 請求項9に記載の計測方法において、
前記計測装置は、前記取得した核磁気共鳴信号に基づき、さらに、前記被検体の磁気共鳴画像を生成すること
を特徴とする計測方法。 - 請求項9に記載の計測方法において、
前記磁場勾配コイルは、円柱状の基台に固定して配設され、
前記磁石及び前記第2の磁石は、前記円柱状の基台の円形上面の周縁部に沿って回動可能に配設され、
前記磁場勾配コイルは、前記磁石及び前記第2の磁石が前記円柱状の基台の円形上面の周縁部に沿って回動するとき、前記磁石及び前記第2の磁石それぞれによってそれぞれ形成される前記静磁場及び前記第2の静磁場の中を相対的に移動すること
を特徴とする計測方法。
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JPH05228125A (ja) * | 1992-02-21 | 1993-09-07 | Toshiba Corp | 磁気共鳴イメージング装置 |
US5304933A (en) * | 1991-08-01 | 1994-04-19 | General Electric Company | Surgical local gradient coil |
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DE102007053429B4 (de) * | 2007-11-09 | 2011-09-22 | Siemens Ag | Lokalspulenanordnung mit Magnetfeldsensor und Magnetresonanzanlage mit derartiger Lokalspulenanordnung |
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US5304933A (en) * | 1991-08-01 | 1994-04-19 | General Electric Company | Surgical local gradient coil |
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CN106772157B (zh) * | 2015-11-24 | 2019-11-19 | 上海联影医疗科技有限公司 | 一种磁共振成像的方法和装置 |
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