JP4219064B2 - Magnetic resonance imaging device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an imaging object transfer apparatus and a magnetic resonance imaging apparatus, and more particularly to an imaging object transfer apparatus that transfers an imaging object to an imaging space located above the imaging object in a state where the upper body is raised, and at least an imaging object. The present invention relates to a magnetic resonance imaging apparatus for imaging in a state where the body is raised.
[0002]
[Prior art]
In a magnetic resonance imaging apparatus, an imaging target is carried into an imaging space in which a static magnetic field is formed, a gradient magnetic field and a high-frequency magnetic field are applied to generate a magnetic resonance signal in the imaging target, and a tomographic image is generated based on the received signal. Generate. Since the imaging target is often a patient, it is carried into the imaging space in a lying state and imaged in that state.
[0003]
Real-time imaging becomes possible as the speed of magnetic resonance imaging increases, and the active brain is imaged not only for patients but also for healthy subjects for academic research. That is, the brain function is elucidated by imaging the brain activity corresponding to sensory stimulation or the brain activity corresponding to the spontaneous movement of each part of the body.
[0004]
[Problems to be solved by the invention]
Since normal human activities are often performed with the upper body raised, imaging for studying brain activity in a lying state does not always accurately capture the actual brain activity. There was no problem.
[0005]
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a magnetic resonance imaging apparatus that performs imaging in a state close to the original activity state of the imaging target, and such a magnetic resonance imaging apparatus. It is to realize an imaging object transfer device for the purpose.
[0006]
[Means for Solving the Problems]
(1) The invention according to the first aspect for solving the above-described problem is that a support means for supporting an imaging target at least in a state where the upper body is raised, and the support means are driven to move the imaging target. It is an imaging object transfer device comprising transfer means for transferring to an imaging space located above.
[0007]
(2) According to a second aspect of the invention for solving the above problem, the transfer means includes a screw rod having a length corresponding to a transfer distance, and a screw rod attached to the support means and screwed to the screw rod. The imaging object transfer device according to (1), further comprising: a nut to be joined, and a driving unit that rotates the screw rod.
[0008]
(3) In a third aspect of the invention for solving the above-described problem, the transfer means includes a suspension mechanism that suspends the support means, and a drive means that drives the suspension mechanism to move the support means up and down. (1). The imaging object transfer device according to (1).
[0009]
(4) In a fourth aspect of the invention for solving the above-described problem, the transfer means includes a pantograph mechanism that supports the support means, and a drive means that drives the pantograph mechanism to move the support means up and down. (1). The imaging object transfer device according to (1).
[0010]
(5) According to a fifth aspect of the invention for solving the above-described problem, a support means for supporting an imaging target in which at least an upper body is raised in the imaging space, and a static magnetic field is formed in the imaging space. A static magnetic field forming means, a gradient magnetic field forming means for forming a gradient magnetic field in the imaging space, a high frequency magnetic field forming means for forming a high frequency magnetic field in the imaging space, and a measuring means for measuring a magnetic resonance signal from the imaging space; The magnetic resonance imaging apparatus further comprises image generation means for generating an image based on the measured magnetic resonance signal.
[0011]
(6) The invention according to a sixth aspect for solving the above-mentioned problem is characterized in that the static magnetic field forming means forms a static magnetic field in a bore whose axial direction is the vertical direction. This is a magnetic resonance imaging apparatus.
[0012]
(7) In a seventh aspect of the invention for solving the above-mentioned problem, the supporting means has a conveying means for carrying the imaging object into the static magnetic field from the lower side of the bore. Item 7. The magnetic resonance imaging apparatus according to Item 6.
[0013]
(8) In an invention according to an eighth aspect for solving the above-mentioned problem, the conveying means carries the imaging object into the bore up to the chest and positions the head at the center of the static magnetic field. The magnetic resonance imaging apparatus according to claim 7.
[0014]
(9) The invention according to a ninth aspect for solving the above-mentioned problem is characterized in that the support means has a seat on which the imaging object is seated. A magnetic resonance imaging apparatus according to one aspect.
[0015]
(10) An invention according to a tenth aspect for solving the above-mentioned problem is the magnetic resonance imaging apparatus according to claim 9, wherein the seat is lower than the floor surface in the lowest state.
[0016]
(11) According to an eleventh aspect of the invention for solving the above-described problem, a transport unit that transports an imaging target to an imaging space, a static magnetic field forming unit that forms a static magnetic field in the imaging space, and the imaging space Based on the measured magnetic resonance signal, a gradient magnetic field forming means for forming a gradient magnetic field, a high frequency magnetic field forming means for forming a high frequency magnetic field in the imaging space, a measuring means for measuring a magnetic resonance signal from the imaging space, and A magnetic resonance imaging apparatus having an image generation means for generating an image, wherein the imaging object transfer apparatus according to any one of claims 1 to 4 is used as the conveying means. A magnetic resonance imaging apparatus.
[0017]
(12) The invention according to a twelfth aspect for solving the above-described problem is that at least one of the static magnetic field forming means, the gradient magnetic field forming means, the high-frequency magnetic field forming means, and the measuring means is the imaging device. The magnetic resonance imaging apparatus according to claim 5, further comprising a contact detection unit configured to detect contact with an object.
[0018]
(13) The magnetic resonance imaging apparatus according to claim 12, wherein the invention according to a thirteenth aspect for solving the above-mentioned problem is characterized in that the contact detection means detects contact based on a change in air pressure. It is.
[0019]
(14) The invention according to a fourteenth aspect for solving the above-described problem is characterized in that the contact detection means is a contact portion with a detection target being an air tube. Device.
[0020]
(15) The invention according to a fifteenth aspect for solving the above-mentioned problems comprises a stop means for stopping the transfer based on a contact detection signal of the contact detection means. Item 15. The magnetic resonance imaging apparatus according to any one of Items 14.
[0021]
(16) According to another aspect of the invention for solving the above-described problem, an imaging target in which at least an upper body is raised in the imaging space is supported, a static magnetic field is formed in the imaging space, and the imaging space is provided. Forming a gradient magnetic field, forming a high-frequency magnetic field in the imaging space, measuring a magnetic resonance signal from the imaging space, and generating an image based on the measured magnetic resonance signal It is.
[0022]
(17) In another aspect of the invention for solving the above problem, an imaging target is conveyed to an imaging space, a static magnetic field is formed in the imaging space, a gradient magnetic field is formed in the imaging space, and the imaging is performed. A magnetic resonance imaging method for forming a high frequency magnetic field in a space, measuring a magnetic resonance signal from the imaging space, and generating an image based on the measured magnetic resonance signal, wherein the transport is performed in (1) to (4) It is a magnetic resonance imaging method characterized by performing using the imaging object transfer apparatus as described in any one of these.
[0023]
(Function)
In the present invention, magnetic resonance imaging of an imaging target is performed at least with the upper body raised. Further, the supporting means for supporting the imaging target is driven at least in a state where the upper body is raised, and the imaging target is transferred to the imaging space located above the imaging target. In addition, contact between the imaging target and the non-moving part in the transfer process is detected to prevent injury due to collision.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the embodiment. FIG. 1 shows a block diagram of the magnetic resonance imaging apparatus. This apparatus is an example of an embodiment of the present invention. An example of an embodiment relating to the apparatus of the present invention is shown by the configuration of the apparatus. An example of an embodiment related to the method of the present invention is shown by the operation of the apparatus.
[0025]
As shown in FIG. 1, the apparatus has a magnet system 11. The magnet system 11 includes a main magnetic field coil unit 101 and a gradient coil unit 105. Each of these coil portions has a substantially cylindrical outer shape and is arranged coaxially with each other. The direction of the bore of the magnet system 11 is a vertical direction. This is called a vertical bore magnet system.
[0026]
A subject 31 to be imaged is seated on the seat 43 and carried into and out of the interior space of the magnet system 11 by the transport means described later. By sitting on the seat 43, the subject 31 stands upright. The seat 43 is an example of an embodiment of the support means in the present invention. Note that the support means is not limited to the seat, and may be one that supports the subject 31 in an upright state, that is, any means that supports at least the upper body in a standing state.
[0027]
The head of the subject 31 is accommodated in an RF coil (radio frequency coil) portion 33 attached to the upper portion of the backrest portion of the seat 43. The RF coil unit 33 also has a substantially cylindrical outer shape, and is disposed coaxially with the main magnetic field coil unit 101 and the gradient coil unit 105 in the internal space of the magnet system 11. The RF coil unit 33 is configured using, for example, a TEM resonator (transverse electromagnetic mode resonator) type RF coil. The RF coil is not limited to the TEM resonator type, and may be an appropriate RF coil such as a birdcage type coil or a saddle type coil.
[0028]
The main magnetic field coil unit 101 forms a static magnetic field in the internal space of the magnet system 11. The main magnetic field coil unit 101 is an example of an embodiment of the static magnetic field forming means in the present invention. The direction of the static magnetic field is the vertical direction. The main magnetic field coil unit 101 is configured using, for example, a superconducting coil. Needless to say, the present invention may be configured using not only a superconducting coil but also a normal conducting coil.
[0029]
The gradient coil unit 105 generates a gradient magnetic field for giving a gradient to the static magnetic field strength. There are three types of gradient magnetic fields that are generated: a slice gradient magnetic field, a read out gradient magnetic field, and a phase encode gradient magnetic field. The gradient coil unit 105 corresponds to these three types of gradient magnetic fields. Has three gradient coils (not shown).
[0030]
The RF coil unit 33 forms a high-frequency magnetic field for exciting spins in the body of the subject 31 in the static magnetic field space. Formation of a high-frequency magnetic field is called transmission of an RF excitation signal. The transmission of the RF excitation signal may be performed by a dedicated RF coil for transmission other than the RF coil unit 33. The RF coil unit 33 also receives an electromagnetic wave generated by excited spin, that is, a magnetic resonance signal.
[0031]
A gradient driving unit 131 is connected to the gradient coil unit 105. The gradient driving unit 131 gives a drive signal to the gradient coil unit 105 to generate a gradient magnetic field. The portion composed of the gradient coil unit 105 and the gradient drive unit 131 is an example of an embodiment of the gradient magnetic field forming means in the present invention. The gradient driving unit 131 includes three systems of driving circuits (not shown) corresponding to the three systems of gradient coils in the gradient coil unit 105.
[0032]
An RF drive unit 141 is connected to the RF coil unit 33. The RF drive unit 141 gives a drive signal to the RF coil unit 33 and transmits an RF excitation signal to excite spins in the body of the subject 31. The portion composed of the RF coil unit 33 and the RF drive unit 141 is an example of an embodiment of the high-frequency magnetic field forming means in the present invention.
[0033]
A data collection unit 151 is connected to the RF coil unit 33. The data collection unit 151 takes in the reception signal received by the RF coil unit 33 and collects it as digital data. The portion composed of the RF coil unit 33 and the data collecting unit 151 is an example of an embodiment of the measuring means in the present invention.
[0034]
The seat 43 on which the subject 31 is seated is driven by the seat driving unit 111 and moves forward and backward in the vertical direction. The portion composed of the seat 43 and the seat drive unit 111 is an example of an embodiment of the transport means in the present invention. The magnet system 11 is provided with a contact sensor (sensor), which will be described later, and the contact detection signal is input to the contact detection unit 121.
[0035]
A control unit 161 is connected to the seat driving unit 111, the gradient driving unit 131, the RF driving unit 141, and the data collection unit 151. The control part 161 controls the seat drive part 111 thru | or the data collection part 151, respectively. A contact detection signal is input from the contact detection unit 121 to the control unit 161.
[0036]
An output signal of the data collection unit 151 is input to the data processing unit 171. The data processing unit 171 stores the data fetched from the data collecting unit 151 in a memory (not shown). A data space is formed in the memory. The data space constitutes a two-dimensional Fourier space. The data processing unit 171 reconstructs a tomographic image of the head of the subject 31 by performing two-dimensional inverse Fourier transform on the data in the two-dimensional Fourier space. The data processing unit 171 is an example of an embodiment of image generation means in the present invention.
[0037]
The data processing unit 171 is connected to the control unit 161. The data processing unit 171 is above the control unit 161 and supervises it. A display unit 181 and an operation unit 191 are connected to the data processing unit 171. The display unit 181 displays the reconstructed image and various information output from the data processing unit 171. The operation unit 191 is operated by an operator and inputs various commands and information to the data processing unit 171.
[0038]
2 and 3 show the appearance of the magnet system 11 together with the subject 31 in a standby state. 2 is a perspective view, and FIG. 3 is a side view partially showing a cross section. As shown in the figure, the magnet system 11 is supported by four support columns 13 provided on the floor surface FL.
[0039]
A pit 21 is provided on the floor surface FL below the magnet system 11. In the pit 21, a staircase 51 descending from the floor surface is provided. The seat 43 on which the subject 31 is seated is lowered to the bottom of the pit 21 by the seat lifting mechanism 41. The seat 43 and the seat elevating mechanism 41 are configured using a nonmagnetic material except for a motor and the like described later.
[0040]
The portion including the seat 43 and the seat lifting mechanism 41 is an example of an embodiment of the imaging target transfer device of the present invention. An example of an embodiment relating to the imaging target transfer device of the present invention is shown by the configuration of the transfer device. The seat elevating mechanism 41 is also an example of an embodiment of the transfer means in the present invention.
[0041]
In front of the subject 31, a keyboard 45 such as a musical instrument is installed. The keyboard 45 is operated by the subject 31 during imaging. The keyboard 45 is integrated with the seat. A mirror (not shown) is provided in the RF coil unit 33 so that the subject 31 can visually recognize the keyboard 45 and its surroundings.
[0042]
In addition, what is operated by the subject 31 is not limited to a keyboard such as a musical instrument. Depending on the purpose of the experiment, for example, a keyboard of an information device, other operating tools, writing tools, tools, and other various instruments operated by hand. It may be. Or you may make it use the instrument operated with a leg | foot depending on the objective of experiment.
[0043]
One of the columns 13 is provided with a lifting operation switch (switch) 47 operated by the operator 35. The lifting operation switch 47 constitutes a part of the operation unit 191. A command based on the operation of the lifting operation switch 47 is given to the seat driving unit 111 through the data processing unit 171 and the control unit 161. Note that the signal of the lifting operation switch 47 may be directly given to the seat driving unit 111.
[0044]
The seat driving unit 111 moves the seat 43 up and down via the seat lifting mechanism 41 according to the command. That is, at the time of imaging, the seat 43 is raised as shown in FIG. 4 to bring the subject 31 into the imaging space together with the RF coil unit 33, and when the imaging is completed, the seat 31 is lowered to the standby position shown in FIGS. The seat lifting mechanism 41 will be described later.
[0045]
FIG. 5 shows the interrelationship between the magnet system 11, the subject 31, and the RF coil unit 33 during imaging. As shown in the figure, the head of the subject 31 and the RF coil unit 33 are located in the center of the magnet system 11, that is, in the imaging region of the magnet center.
[0046]
The inner wall of the gradient coil section 105 constitutes the inner wall of the bore. On the inner wall of the bore, the diameter of the head receiving portion is smaller than the diameter of the chest receiving portion, and there is a step at the boundary. A contact sensor 61 is provided on the lower surface of the step portion. The contact sensor 61 detects when the shoulder portion of the subject 31 is in contact with the seat 43 ascending.
[0047]
A contact sensor 63 is provided around the opening below the bore of the magnet system 11. The contact sensor 63 detects when the hand or the like of the subject 31 placed on the keyboard 45 comes into contact with the seat 43 ascending.
[0048]
The detection signals of these contact sensors 61 and 63 are input to the contact detection unit 121. The contact detection unit 121 detects contact based on the sensing signal and notifies the control unit 161 of the contact. The control unit 161 stops the raising of the seat 43 through the seat driving unit 111 based on the notification signal. This prevents the subject 31 from being pressed by the stepped portion in the bore and the lower surface of the magnet system 11.
[0049]
When the RF coil unit 33 is fixed in the bore instead of being attached to the seat 43, a contact sensor is also provided at the lower end of the RF coil unit 33. Thereby, the test subject 31 can be prevented from being compressed by the RF coil unit 33.
[0050]
The portion composed of the contact sensors 61 and 63 and the contact detection unit 121 is an example of the embodiment of the contact detection means in the present invention. The part which consists of the control part 161 and the seat drive part 111 is an example of embodiment of the stop means in this invention.
[0051]
An example of the configuration of the contact sensor 61 is shown in FIG. The configuration of the contact sensor 63 is also the same. As shown in the figure, the contact sensor 61 has a ring-shaped sensing unit 601. The sensing unit 601 is a hollow body with one end closed, and constitutes an air tube. A hose 603 communicating with the hollow portion is provided at the other end of the sensing unit 601.
[0052]
The sensing unit 601 is made of a flexible material such as rubber. For this reason, the internal air is compressed by contact with another object, and a pressure increase associated therewith is transmitted to the contact detection unit 121 through the hose 603. Since the contact sensor 61 uses a change in air pressure due to contact, noise caused by on / off, or artifacts due to the presence of metal, and the like do not occur as in the case of using an electrical contact. For this reason, the contact sensor 61 is very convenient to be provided in or near the bore.
[0053]
As the contact detection unit 121, for example, a pressure switch schematically shown in FIG. 7 is used. Note that the pressure switch is disposed sufficiently away from the imaging space. (A) of the figure shows the off (off) state of the pressure switch, and (b) shows the on (on) state.
[0054]
As shown in the figure, the pressure switch has a diaphragm box 605. The inside of the diaphragm box 605 is divided into two chambers 609 and 609 ′ by a diaphragm 607. A chamber 609 communicates with the contact sensor 61 by a hose 603.
[0055]
One of the pair of electrical contacts is provided at the center of the diaphragm 607, and the other electrical contact is provided on the wall surface of the chamber 609 'facing the diaphragm 607. These electrical contacts come into contact when the diaphragm 607 is pushed by a pressure difference caused by a sensing signal (air pressure) of the contact sensor 61.
[0056]
Due to the contact of the electrical contact, a current flows from a power source (not shown) through a relay coil 611 connected in series to the relay coil 611 to turn on the relay contact 613. The ON state of the relay contact 613 is input to the control unit 161 as a contact detection signal. A similar pressure switch is also provided for the contact sensor 63.
[0057]
FIG. 8 shows a schematic configuration of the seat lifting mechanism 41 in relation to the seat 43. As shown in the figure, this mechanism has a screw rod 401. The screw rod 401 is an example of an embodiment of the screw rod in the present invention. Both ends of the screw rod 401 are supported by bearings (not shown) and extend in the vertical direction. The length of the screw rod 401 is slightly longer than the predetermined lifting distance of the seat 43.
[0058]
A pulley 403 is fixed to the lower end portion of the screw rod 401, and the rotation of the pulley 407 is transmitted to the pulley 403 via a belt 405. The pulley 407 is driven and rotated by a motor 411 coupled through a direction changer 409. The motor 411 can rotate in both forward and reverse directions. A portion including the pulley 407 or the motor 411 is an example of an embodiment of the driving means in the present invention.
[0059]
A nut 413 is screwed onto the screw rod 401. The nut 413 is an example of an embodiment of the nut in the present invention. The side surface of the nut 413 is fixed to the back surface of the seat 43. The seat 43 is formed by integrating a stool portion 431, a footrest portion 433, and a backrest portion 435. The height of the stool portion 431 from the footrest portion 433 can be adjusted. An RF coil portion 33 is attached to the upper portion of the backrest portion 435.
[0060]
The seat 43 has a movable direction limited to a vertical direction by a guide mechanism (not shown). For this reason, the seat 43 can be raised by rotating the screw rod 401 in the spiral backward direction by the motor 411, and the seat 43 can be lowered by rotating in the spiral traveling direction.
[0061]
Such a seat elevating mechanism 41 uses the screwing of the screw rod 401 and the nut 413, and thus has an advantage that the seat 43 is unlikely to descend due to its own weight even if the driving by the motor 411 is stopped. For this reason, a brake for preventing the lowering can be substantially eliminated, and even if provided, a brake with a very weak braking force can be used. Further, the lifting mechanism using the screw rod has an advantage that it is difficult to break down because of its simple structure, and further has an advantage of excellent space saving.
[0062]
FIG. 9 shows a schematic configuration of another embodiment of the seat lifting mechanism 41. As shown in the figure, the elevating mechanism uses a pantograph mechanism. That is, a pantograph mechanism 425 is interposed between a movable base 421 with the seat 43 mounted thereon and a fixed base 423 whose position is fixed, and the pantograph mechanism 425 is driven by a hydraulic cylinder 427 from the fixed base 423 side. By doing so, the seat 43 is raised and lowered. Of course, instead of the hydraulic cylinder 427, a linear drive mechanism using a combination of a screw rod and a nut may be used.
[0063]
The pantograph mechanism 425 is an example of an embodiment of the pantograph mechanism in the present invention. The hydraulic cylinder 427 is an example of an embodiment of drive means in the present invention.
[0064]
FIG. 10 shows a schematic configuration of another embodiment of the seat elevating mechanism 41. As shown in the figure, the lifting mechanism uses a suspension mechanism. That is, the seat 43 is suspended by a strip 455 that is wound around two fixed pulleys 451 and 453 that are fixed in position. The fixed pulleys 451 and 453 are arranged at a predetermined distance in the vertical direction. The fixed pulley 451 is on the upper side, and the fixed pulley 453 is on the lower side. The strip 455 has one end fixed to the seat 43 and the other end fixed to a predetermined fixed point on the lower side. As the strip 455, for example, a chain, a belt, a wire, or the like is used.
[0065]
The strip 455 hangs the lower fixed point and the intermediate portion of the fixed pulley 453 around the movable pulley 457. Then, the seat 43 is moved up and down by moving the movable pulley 457 in the horizontal direction by the hydraulic cylinder 459. Of course, instead of the hydraulic cylinder 459, a linear drive mechanism using a combination of a screw rod and a nut may be used.
[0066]
The portion composed of the fixed pulleys 451 and 453 and the strip 455 is an example of the embodiment of the suspension mechanism in the present invention. The portion composed of the movable pulley 457 and the hydraulic cylinder 459 is an example of the embodiment of the driving means in the present invention.
[0067]
The operation of this apparatus will be described. First, the operator 35 seats the subject 31 on the seat 43 descending in the pit 21 and houses the head in the RF coil section 33. Next, the switch 47 is operated to operate the seat elevating mechanism 41 to raise the seat 43 and convey it to the imaging position shown in FIG. In the middle of this, when the subject 31 comes into contact with the contact sensor 61 or 63, the conveyance is stopped, and the subject 31 is prevented from being harmed.
[0068]
Next, the operator 35 operates the operation unit 191 to start imaging. Imaging proceeds under the control of the control unit 161. FIG. 11 shows an example of a pulse sequence used for magnetic resonance imaging. This pulse sequence is a pulse sequence of a spin echo (SE: Spin Echo) method.
[0069]
That is, (1) is a sequence of 90 ° pulse and 181 ° pulse for RF excitation in the SE method, and (2), (3), (4) and (5) are also slice gradient Gs and lead, respectively. This is a sequence of an out gradient Gr, a phase encode gradient Gp, and a spin echo MR. The 90 ° pulse and the 181 ° pulse are each represented by a center signal. The pulse sequence proceeds from left to right along the time axis t.
[0070]
As shown in the figure, 90 ° excitation of spin is performed by a 90 ° pulse. At this time, the slice gradient Gs is applied, and selective excitation for a predetermined slice is performed. After a predetermined time from the 90 ° excitation, 180 ° excitation by a 180 ° pulse, that is, spin inversion is performed. At this time, the slice gradient Gs is applied, and selective inversion is performed for the same slice.
[0071]
In the period between 90 ° excitation and spin reversal, a readout gradient Gr and a phase encode gradient Gp are applied. Spin dephase is performed by the lead-out gradient Gr. Spin phase encoding is performed by the phase encoding gradient Gp.
[0072]
After the spin inversion, the spin is rephased at the readout gradient Gr to generate the spin echo MR. The spin echo MR is an RF signal having a symmetrical waveform with respect to the echo center. The central echo occurs after TE (echo time) from 90 ° excitation. The spin echo MR is collected as view data by the data collecting unit 151. Such a pulse sequence is repeated 64 to 512 times in a cycle TR (repetition time). The phase encoding gradient Gp is changed every time it is repeated, and a different phase encoding is performed each time. Thereby, view data of 64 to 512 views is obtained.
[0073]
Another example of the pulse sequence for magnetic resonance imaging is shown in FIG. This pulse sequence is a pulse sequence of a gradient echo (GRE) method.
[0074]
That is, (1) is a sequence of α ° pulses for RF excitation in the GRE method, and (2), (3), (4) and (5) are respectively slice gradient Gs, readout gradient Gr, It is a sequence of a phase encoding gradient Gp and a spin echo MR. The α ° pulse is represented by a center signal. The pulse sequence proceeds from left to right along the time axis t.
[0075]
As shown in the figure, the α ° excitation of the spin is performed by the α ° pulse. α is 90 or less. At this time, the slice gradient Gs is applied, and selective excitation for a predetermined slice is performed.
[0076]
After the α ° excitation, spin phase encoding is performed by the phase encoding gradient Gp. Next, the spin is first dephased by the readout gradient Gr, and then the spin is rephased to generate a gradient echo MR. The gradient echo MR is an RF signal having a symmetrical waveform with respect to the echo center. The central echo occurs after TE from α ° excitation.
[0077]
The gradient echo MR is collected as view data by the data collection unit 151. Such a pulse sequence is repeated 64 to 512 times with a period TR. The phase encoding gradient Gp is changed every time it is repeated, and a different phase encoding is performed each time. Thereby, view data of 64 to 512 views is obtained.
[0078]
View data obtained by the pulse sequence of FIG. 11 or 12 is collected in the memory of the data processing unit 171. Note that the pulse sequence is not limited to the SE method or the GRE method, and may be of any other appropriate technique such as the Fast Spin Echo (FSE) method or Echo Planar Imaging (EPI). It goes without saying.
[0079]
The data processing unit 171 reconstructs a tomographic image of the head of the subject 31 by performing two-dimensional inverse Fourier transform on the view data. The reconstructed image is displayed as a visible image by the display unit 181.
[0080]
Such imaging is performed while the subject 31 performs a predetermined keyboard operation, and the brain function of the subject 31 is examined based on the obtained image. Since the subject 31 performs the keyboard operation in the state where the upper body is raised, the operation can be performed in a state similar to a normal action of a human. This makes it possible to correctly capture the brain function during normal action.
[0081]
It should be noted that not only when the subject 31 performs the finger operation as described above, but also when, for example, imaging the state of the brain when performing language pronunciation, singing, recalling a thought, etc., the function of the brain during normal action Can be imaged correctly. Furthermore, not only the self-issued movement of the subject 31 as described above, but also the case of imaging the behavior of the brain with respect to sensory organ stimuli such as vision, hearing, taste, smell, and touch.
[0082]
【The invention's effect】
As described above in detail, according to the present invention, a magnetic resonance imaging apparatus that performs imaging in a state close to the original activity state of the imaging target, and an imaging target transfer apparatus for such a magnetic resonance imaging apparatus. Can be realized.
[Brief description of the drawings]
FIG. 1 is a block diagram of an exemplary apparatus according to an embodiment of the present invention.
FIG. 2 is a perspective view showing an appearance of a magnet system of the apparatus shown in FIG. 1 together with an imaging target in a standby state.
3 is a side view showing the appearance of the magnet system of the apparatus shown in FIG. 1 together with an imaging target and an operator in a standby state.
4 is a perspective view showing an appearance of a magnet system of the apparatus shown in FIG. 1 together with an imaging target in an imaging state. FIG.
FIG. 5 is a diagram illustrating a relationship between an imaging target and a magnet system in an imaging state.
6 is a plan view of a contact sensor provided in the magnet system shown in FIG. 5. FIG.
7 is a schematic diagram of a contact detection unit in the apparatus shown in FIG. 1. FIG.
8 is a diagram showing a schematic configuration of a seat lifting mechanism in the apparatus shown in FIG. 1. FIG.
9 is a diagram showing a schematic configuration of a seat lifting mechanism in the apparatus shown in FIG. 1. FIG.
10 is a diagram showing a schematic configuration of a seat lifting mechanism in the apparatus shown in FIG. 1. FIG.
11 is a schematic diagram showing an example of a pulse sequence executed by the apparatus shown in FIG. 1. FIG.
12 is a schematic diagram showing an example of a pulse sequence executed by the apparatus shown in FIG. 1. FIG.
[Explanation of symbols]
11 Magnet system 31 Imaging target 33 RF coil unit 41 Seat elevating mechanism 43 Seat 45 Keyboard 61, 63 Touch sensor 101 Main magnetic field magnet unit 105 Gradient coil unit 111 Seat drive unit 121 Contact detection unit 131 Gradient drive unit 141 RF drive unit 151 Data Collection unit 161 Control unit 171 Data processing unit 181 Display unit 191 Operation unit 401 Screw rod 403, 407 Pulley 405 Belt 411 Motor 421 Movable base 423 Fixed base 425 Pantograph mechanism 427 Hydraulic cylinder 451, 453 Fixed pulley 455 Strip 457 Movable pulley 459 Hydraulic cylinder

Claims (12)

Static magnetic field forming means having a cylindrical outer shape whose central axis is directed in the vertical direction, wherein a static magnetic field is formed in an imaging space in which a lower surface inside the cylindrical outer shape is opened Means,
A gradient magnetic field forming means for forming a gradient magnetic field in the imaging space;
High-frequency magnetic field forming means for forming a high-frequency magnetic field in the imaging space;
A support means for supporting an imaging object in which at least the upper body is raised;
Measuring means for measuring a magnetic resonance signal from the imaging space;
Image generating means for generating an image based on the measured magnetic resonance signal;
A magnetic resonance imaging apparatus comprising:
By moving the support means up and down in a vertical direction from a position below the floor surface on which the apparatus main body is installed to the imaging space, the imaging target is carried into the imaging space, and the imaging target is removed from the imaging space. It has conveying means to carry out,
A magnetic resonance imaging apparatus, wherein a passage through which the imaging target passes is formed from the floor surface to a position below the floor surface.   The magnetic resonance imaging apparatus according to claim 1, wherein the static magnetic field forming unit forms a vertical static magnetic field in a bore having the vertical direction as an axial direction.   3. The magnetic resonance imaging apparatus according to claim 1, wherein the transport unit carries the imaging target up to the chest into the bore and positions a head in the center of the static magnetic field.   The magnetic resonance imaging apparatus according to claim 1, wherein the support unit includes a seat on which the imaging target is seated.   The magnetic resonance imaging apparatus according to claim 4, wherein the seat is lower than a floor surface when the seat is lowered.   The conveying means includes a screw rod having a length corresponding to a transfer distance, a nut attached to the support means and screwed into the screw rod, and a driving means for rotating the screw rod. The magnetic resonance imaging apparatus according to claim 1, wherein the magnetic resonance imaging apparatus is a magnetic resonance imaging apparatus.   The said conveyance means is equipped with the suspension mechanism which suspends the said support means, and the drive means which drives the said suspension mechanism and raises and lowers the said support means, The Claim 1 thru | or 5 characterized by the above-mentioned. The magnetic resonance imaging apparatus according to any one of the above.   The said conveyance means is equipped with the pantograph mechanism which supports the said support means, and the drive means which drives the said pantograph mechanism and raises and lowers the said support means, The Claim 1 thru | or 5 characterized by the above-mentioned. The magnetic resonance imaging apparatus according to any one of the above.   The at least one of the static magnetic field forming unit, the gradient magnetic field forming unit, the high-frequency magnetic field forming unit, and the measuring unit includes a contact detection unit that detects contact with the imaging target. The magnetic resonance imaging apparatus according to any one of claims 1 to 8.   The magnetic resonance imaging apparatus according to claim 9, wherein the contact detection unit detects contact based on a change in air pressure.   The magnetic resonance imaging apparatus according to claim 10, wherein the contact detection means is an air tube at a contact portion with a detection target.   The magnetic resonance imaging apparatus according to claim 9, further comprising a stopping unit that stops the transfer based on a contact detection signal of the contact detection unit.

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