JPH10155762A - Magnetic resonance tomograph - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a higher inspection efficiency. SOLUTION: This magnetic resonance tomograph has an open type gantry 1 with the side of a photographing area space S opened and a first bed Ba with a top plate Ta being loaded or unloaded from the front of the gantry and a second bed Bb with a top plate Tb being loaded or unloaded from the side thereof are so arranged to be orthogonal to each other in the direction of moving thereof while generated magnetic fields of an X gradient magnetic field coil 3X and an Y gradient magnetic field coil 3Y are changed over with the replacement of the beds Ba and Bb. Preparations are made for the photographing of the bed Bb during the photographing using the bed Ba and when the photographing using the bed Ba is ended, in turn, the top plate Tb of the bed Bb is advanced to start photographing thereby shortening the downtime of the apparatus.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic resonance tomography apparatus which obtains an MR image by performing tomography of a subject by utilizing a nuclear magnetic resonance phenomenon, and more particularly to a technique for improving examination efficiency.

[0002]

2. Description of the Related Art In recent years, a magnetic resonance tomography apparatus (hereinafter abbreviated as "MRI apparatus" as appropriate) for performing imaging utilizing the NMR phenomenon has been widely used in the field of medical form diagnosis. As shown in FIG. 12, the conventional MRI apparatus includes a cylindrical gantry 51 having an imaging region space S, and a main static magnetic field forming main unit for forming a uniform static magnetic field in the imaging region space S in the gantry 51. A magnet 52 and three gradient magnetic field coils (not shown) whose magnetic field strengths change in three-dimensional directions are provided. In the vicinity of the gantry 51, a bed 54 for placing the table 53 in and out of the imaging region space S with the subject M lying on the table 53 is arranged. An RF signal (excitation magnetic field pulse) is applied to the subject M carried into the imaging region space S by the top plate 53, for example, by the abdominal RF coil P,
An NMR signal (echo magnetic field pulse) is detected from the subject M. Image reconstruction is performed based on the detected NMR signal, and an MR image is finally obtained.

[0003]

However, the conventional M
In the case of the RI device, there is a problem that the inspection efficiency (imaging efficiency) is not good. In the conventional MRI apparatus, after the end of imaging, the top 53 on which the subject M is placed is returned to the standby position (the state shown in FIG. 12) outside the gantry 51, and the RF coil P is removed from the subject M to remove the subject M. Take down. Then, after the next subject M is placed on the top 53, the RF coil P is put on, and the top 53 enters the gantry 51. Therefore, the top plate 53
In fact, the MRI apparatus is at rest between the time when the user exits and the time when the user reenters the next time. On the other hand, RF
It takes a considerable amount of time to remove the coil P and to get on and off the subject M. It takes more time when the type of the RF coil P is changed or when the medical condition of the subject M is severe. as a result,
The downtime of the MRI apparatus is prolonged, and it is difficult to carry out the examination with high efficiency. There are various types of RF coils for the head, knees, spinal cord, and the like, in addition to those mounted on the subject such as the RF coil P for the abdomen. Inspection cannot proceed efficiently.

[0004] In view of the above problems, an object of the present invention is to provide a magnetic resonance tomography apparatus capable of improving inspection efficiency.

[0005]

In order to achieve the above object, a magnetic resonance tomography apparatus according to the present invention includes a gantry having an imaging region space in which tomography of a subject is performed, and a uniform gantry in the imaging region space. A main magnet for forming a static magnetic field, and an XYZ for generating three gradient magnetic field pulses in the imaging region space in which the direction of the line of magnetic force is in the same direction as the static magnetic field and the magnetic field strength changes in three-dimensional directions orthogonal to each other. Each gradient magnetic field coil, an RF coil for applying an RF signal (excitation magnetic field pulse) and detecting an NMR signal (nuclear magnetic resonance signal), and a bed for taking the subject into and out of the imaging region space while lying down on the subject In the magnetic resonance tomography apparatus provided, (a) the gantry is an open type gantry in which a side of an imaging region space is opened; The table has at least a first bed for taking in and out of the subject from one side of the imaging region space, and a subject from another side of the imaging region space, which is orthogonal to the direction of taking in and out of the subject by the first couch. (C) the main magnet is divided and arranged above and below the imaging region space to generate a uniform static magnetic field in the vertical direction, and (d) the Z gradient magnetic field coil comprises a static magnetic field. (E) The X gradient magnetic field coil generates a magnetic field whose magnetic field intensity changes in the direction in which the subject moves in and out of the subject, and (f) the Y gradient magnetic field coil generates a magnetic field whose magnetic field intensity changes in the same direction. (G) generating a magnetic field in which the magnetic field intensity changes in the direction in which the subject moves in and out of the subject by the second couch, and (g) when performing imaging using the first couch, the X gradient magnetic field coil is used to select a slice plane; Generates a magnetic field pulse, the second When performing imaging using a couch, the gradient magnetic field pulses generated from the X and Y gradient magnetic field coils are switched according to the couch used for imaging so that the Y gradient magnetic field coil generates a gradient magnetic field pulse for selecting a slice plane. A gradient magnetic field pulse switching means is provided.

[Operation] Next, the operation when tomography is performed by the MRI apparatus of the present invention will be described. First, the subject to be imaged is placed on the first bed and RF
After the coil is mounted on the subject, the subject is advanced into the gantry, and the subject is set in the imaging region space where tomography is performed. Subsequently, the RF signal (excitation magnetic field pulse) is applied by the RF coil and the NMR signal (echo magnetic field pulse) is detected, together with the static magnetic field generated by the main magnet and the gradient magnetic field pulse generated by the XYZ gradient magnetic field coils. The obtained NMR signal is sent to the image reconstructing unit, where processing necessary for creating and displaying an MR image is performed. After the imaging, the subject is retracted to the standby position.

[0007] While the imaging is being performed as described above, preparations such as mounting the subject to be imaged next on the second bed in standby and mounting the RF coil on the subject are performed. deep. Then, instead of leaving the subject on the first couch that has been photographed, the subject on the second couch is advanced into the gantry, and the subject is subjected to tomography. And shoot in the same way. Of course, the RF coil is removed from the subject on the first bed that has retreated to the standby position, the subject is lowered, and preparation for the next subject starts.

Since the first bed and the second bed are at right angles to each other and the roles of the XY gradient magnetic field coils are interchanged, the first bed and the second bed are used for imaging using the first bed. Is used so that the X gradient magnetic field coil generates a gradient magnetic field pulse for selecting a slice plane, and when performing imaging using the second bed, the Y gradient magnetic field coil generates a gradient magnetic field pulse for selecting a slice plane. The gradient magnetic field pulse generated from the X, Y gradient magnetic field coils is switched by the gradient magnetic field pulse switching means in accordance with the bed used for (1).

That is, in the MRI apparatus of the present invention, two beds which enter and exit from the side of the open type gantry are provided, and another second bed is used while the first bed is used to perform imaging. Prepare the next imaging on the couch, and when the imaging using the first couch is completed, the subject on the second couch enters the imaging area space instead of the first couch and starts the next imaging, The time during which the device is at rest is reduced.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the MRI apparatus of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing the configuration of an MRI apparatus according to the embodiment, mainly focusing on an imaging unit. FIG. 2 is a block diagram showing the configuration of the embodiment apparatus, focusing on a control unit. FIG. It is a top view.

As shown in FIGS. 1 to 3, an MRI apparatus according to an embodiment includes a gantry 1 having an imaging region space S in which a tomographic image of a subject (patient) is taken, a main magnet 2 for forming a static magnetic field, and , XYZ gradient magnetic field coils (Gradient Field Coil) 3 (3X, 3Y,
3Z), RF signal (excitation magnetic field pulse) application and NM
R for detecting an R signal (nuclear magnetic resonance signal)
A first bed B including an F coil (Radio Frequency Coil) 4 and a top plate Ta that enters and exits the imaging region space S from the front.
a, a second bed Bb provided with a top plate Tb which enters and exits from the side of the photographing area space S, and a control console A and a second bed Bb for photographing using the first bed Ba. It is composed of a control console B for photographing. The examination room in which the MRI apparatus of the embodiment is installed is surrounded by a magnetic shield wall WA, as shown in FIG. 3, and the whole is magnetically shielded. Hereinafter, the configuration of each unit will be described more specifically.

The gantry 1 of the embodiment is a so-called open type gantry in which the front, rear and both sides of the photographing area space S are open. The main magnet 2 is disposed vertically above and below the photographing area space S, and is arranged in the vertical direction (Z
Direction) in the imaging region space S. Each of the schematically illustrated XYZ gradient magnetic field coils 3 (3X, 3Y, 3Z) has a magnetic field line in the XYZ direction (three-dimensional direction) orthogonal to the static magnetic field and in the imaging region space S. It is configured to generate three gradient magnetic field pulses, each of which varies in intensity, superimposed on a static magnetic field. As the RF coil 4, in addition to a coil attached to the subject like an RF coil for abdomen, it is placed on the top plate Ta, Tb like an RF coil for a head or a knee, or used for a spinal cord. For example, a coil placed in the imaging region space S like the RF coil of FIG.

In the apparatus of the embodiment, as shown in FIG. 3, the examination room is divided into two by an inner wall WB erected so as to partition between the beds Ba and Bb.
It is structured to be put separately from Db. The inner wall W
The closet C provided in B is a common shelf and is used for storing necessary equipment such as an RF coil and a cushion.
Also, the inner wall WB need not be a magnetic shield wall.

The top plate Ta is moved from the standby position (the state shown in FIG. 1) to X
It is possible to advance in the axial direction and enter the photographing area space S of the gantry 1, and to retreat in the X-axis direction to come out of the photographing area space S and return to the standby position.
Further, the top plate Tb can also advance in the Y-axis direction from the standby position (the state of FIG. 1) and enter the imaging region space S of the gantry 1, and retreat in the Y-axis direction to exit from the imaging region space S. It can come out and return to the standby position. Therefore, both the top plates Ta and Tb are arranged so that the movement directions are orthogonal to each other. The movement control of these top plates Ta and Tb is performed by control consoles A and B. Further, from the viewpoint of accident prevention, a safety circuit (not shown) is provided so that when either one of the top plates Ta and Tb is operating, the other top plate is automatically locked so as not to operate.

Next, the configuration of the control consoles A and B will be described. As described above, the control console A is the first
The control console B is used when shooting using the couch Ba, and the control console B is used when shooting using the second couch Bb.
Since both control consoles A and B have almost the same configuration except that the generated magnetic fields of the X gradient magnetic field coil and the Y gradient magnetic field coil are reversed, the control console A will be described below.

A gradient magnetic field power supply 5 is connected to the gradient magnetic field coil 3 to supply electric power required for generating the respective gradient magnetic fields Gx, Gy, Gz. A waveform signal from the waveform generator 6 is input to the gradient magnetic field power supply 5, and the gradient magnetic field Gx, G
The y, Gz gradient magnetic field waveforms are controlled. On the other hand, a necessary drive signal is supplied from the RF power amplifier 7 to the RF coil 4, whereby an RF signal to the subject is applied. This RF signal is obtained by converting an RF band oscillation signal generated by an RF signal generator 8 into an AM (amplitude) modulator 9.
Are AM-modulated according to the waveform sent from the waveform generator 6.

The NMR signal generated by the subject is received by the RF coil 4 and passes through the preamplifier 10 to the phase detector 1.
Sent to 1. In the phase detector 11, the received signal is R
The phase detection is performed using the RF signal from the F signal generator 8 as a reference signal, and the detection output is sent to the AD converter 12. This A
The D converter 12 converts the detected waveform into digital data according to the sampling pulse from the sampling pulse generator 13. The digital data is taken into the host computer (data processing means) 14. MRI
Operations necessary for operating the apparatus are performed by the operation unit 17 including a keyboard and the like.

The host computer 14 processes the acquired data to reconstruct an image and outputs a tomographic image.
5 and a function of managing the operation timing of the entire apparatus via the sequencer 16. Also,
The host computer 14 also has a function of sending waveform information to the waveform generator 6 and controlling the waveform, intensity, and the like of each of the gradient magnetic field pulses Gx, Gy, and Gz, but the control console A and the control console B are slightly different. . In the case of imaging using the first bed Ba, as shown in FIG. 6, since the X direction is along the body axis of the subject, a gradient magnetic field pulse for slice plane selection is generated from the gradient magnetic field coil 3X. . On the other hand, in the case of imaging using the second bed Bb, as shown in FIG. 9, since the Y direction is along the body axis of the subject, the gradient magnetic field pulse for slice plane selection is supplied from the gradient magnetic field coil 3Y. generate. That is, the magnetic field generated by the X gradient magnetic field coil 3X and the Y gradient magnetic field coil 3Y is switched by the gradient magnetic field pulse switching means according to the bed used. This gradient magnetic field pulse switching means is constituted mainly by the host computer 14 and the waveform generator 6.

Next, the imaging operation of the MRI apparatus of the embodiment having the above-described configuration will be specifically described with reference to FIGS.

First, as shown in FIG. 4, the subject MA to be imaged is placed on the top plate Ta of the first bed Ba, and for example, the abdominal RF coil 4A is mounted on the subject MA. Thereafter, as shown in FIG. 5, the top plate Ta is advanced into the gantry 1, and the subject MA is set in the imaging region space S.

Subsequently, while a static magnetic field is applied from the main magnet 2, a gradient magnetic field pulse is applied from each of the XYZ gradient magnetic field coils 3, and an RF coil 4A
Signal application and NMR signal detection and collection are performed, and imaging proceeds.

That is, the X gradient magnetic field coil 3X is configured as shown in FIG.
As shown in FIG. 10 (b), a gradient magnetic field pulse for slice plane selection is generated, and the Y gradient magnetic field coil 3Y generates a read gradient magnetic field pulse as shown in FIG. 3Z generates a gradient magnetic field pulse for phase encoding as shown in FIG. Further, as shown in FIG. 10A, the RF coil 4A
After applying A and PB, the NMR signal PC is detected.

On the other hand, during imaging using the first bed Ba, the subject MB to be imaged next is placed on the top plate Tb of the second bed Bb, and the RF coil 4B is connected. Attachment to the subject MB is performed in parallel to prepare for the next imaging.

When the imaging of the subject MA is completed, as shown in FIG. 7, the top plate Ta is retracted to the standby position,
Instead, insert the top plate Tb into the gantry 1,
The subject MB is set in the imaging region space S. On the top plate Ta that has exited, the RF coil 4A is removed from the subject MA and the subject MA is lowered.

In the photographing using the second bed Bb, in the state where the static magnetic field is applied by the main magnet 2, the gradient magnetic field pulses are applied by the XYZ gradient magnetic field coils 3 and
Application of an RF signal by the RF coil 4A and detection and collection of an NMR signal are performed, and imaging proceeds.

That is, the X gradient magnetic field coil 3X is configured as shown in FIG.
As shown in FIG. 1 (b), a gradient magnetic field pulse for reading is generated, and the Y gradient magnetic field coil 3Y generates a gradient magnetic field pulse for slice plane selection as shown in FIG. 3Z generates a gradient magnetic field pulse for phase encoding as shown in FIG. FIG. 10 and FIG.
Comparing FIG. 1 shows that the gradient magnetic field pulse generated from the X gradient magnetic field coil 3X and the gradient magnetic field pulse generated from the Y gradient magnetic field coil 3Y are switched. Further, as shown in FIG. 11A, the RF coil 4B
After applying the F signals PA and PB, the NMR signal PC is detected.

While imaging using the second bed Bb, the subject MC to be imaged next is placed on the top plate Ta of the first bed Ba, as shown in FIG. , RF
Attach the coil 4A to the subject MC in parallel, and prepare for the next imaging.

When the imaging of the subject MB is completed, the table Tb is retracted to the standby position, the table Ta is advanced into the gantry 1, and the same operation is repeated again, so that the inspection can be performed efficiently. It will be done. It is needless to say that, even when another type of RF coil is used, the imaging is similarly performed and the inspection is performed efficiently.

The present invention is not limited to the above embodiment, but can be modified as follows.
(1) In the above embodiment, two beds are used. However, a modification in which one bed and another bed are further installed on the opposite side of the bed Bb, and a total of three beds are provided, can be mentioned. . Further, a configuration in which one bed and another bed are further installed on the opposite side of the bed Ba, and a total of four beds are provided is also a modified example.

(2) In the above embodiment, two control consoles are provided.
As a modified example, a switch mechanism in which the terminals of the X gradient magnetic field coil 3X and the Y gradient magnetic field coil 3Y are switched in conjunction with the exchange of a and Bb and the switching of the gradient magnetic field pulse is performed is mentioned.

[0031]

According to the magnetic resonance tomography apparatus of the present invention, a plurality of berths are provided, and preparation for the next radiographing is performed on another berth while radiographing is being performed using one berth. As soon as imaging using one couch is completed, the subject can be immediately entered using the other couch and the next imaging can be started. Increases efficiency.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a schematic configuration of an imaging unit of an MRI apparatus according to an embodiment.

FIG. 2 is a block diagram illustrating a schematic configuration of a control unit of the apparatus according to the embodiment.

FIG. 3 is a plan view showing an installed state of the embodiment device.

FIG. 4 is a schematic plan view showing a state in which a bed Ba is preparing for imaging.

FIG. 5 is a schematic plan view showing a state where a bed Ba is being photographed and a bed Bb is being prepared for photographing.

FIG. 6 shows a subject MA and XYZ during imaging using a bed Ba.
It is a figure showing the relation of an axis.

FIG. 7 is a schematic plan view showing a state in which a bed Ba has been shot and a bed Bb has been shot.

FIG. 8 is a schematic plan view showing a state where a bed B is being photographed and a bed Ba is being prepared for photographing.

FIG. 9 shows a subject MB and XYZ during imaging using the bed Bb.
It is a figure showing the relation of an axis.

FIG. 10 is a diagram showing a pulse sequence at the time of photographing using the bed Ba.

FIG. 11 is a diagram showing a pulse sequence at the time of imaging using the bed Bb.

FIG. 12 is a diagram showing a schematic configuration of a conventional MRI apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Gantry 2 ... Main magnet 3 ... Gradient magnetic field coil 3X ... X gradient magnetic field coil 3Y ... Y gradient magnetic field coil 3Z ... Z gradient magnetic field coil 4 ... RF coil 4A, 4B ... RF coil 14 ... Host computer Ba, Bb ... Bed Ta , Tb: Top plate MA to MC: Subject S: Imaging area space PA, PB: RF signal PC: NMR signal

Claims (1)

[Claims] 1. A gantry having an imaging region space in which a tomographic image of a subject is taken, a main magnet for forming a uniform static magnetic field in the imaging region space, and a direction of a magnetic field line in the imaging region space is the static magnetic field. XYZ gradient magnetic field coils for generating three gradient magnetic field pulses in which the magnetic field strength changes in the same direction and in three-dimensional directions orthogonal to each other, the application of an RF signal (excitation magnetic field pulse) and the NMR signal (nuclear magnetic field) An RF coil for detecting a resonance signal);
In a magnetic resonance tomography apparatus including a bed for taking the subject into and out of the imaging region space while lying down,
(A) The gantry is an open type gantry in which the side of an imaging region space is open, and (b) the bed is at least a first bed for taking a subject in and out of one side of the imaging region space. A second bed for moving the subject in and out from another side of the imaging region space, which is orthogonal to the direction in which the subject moves in and out of the first bed.
(C) The main magnet is divided vertically above and below the imaging area to generate a uniform static magnetic field in the vertical direction. (D) The Z gradient coil generates a magnetic field whose magnetic field intensity changes in the same direction as the static magnetic field. (E) The X gradient magnetic field coil generates a magnetic field whose magnetic field intensity changes in the direction in which the subject moves in and out of the first bed, and (f) the Y gradient magnetic field coil generates in the direction in which the subject moves in and out of the second bed. (G) When the imaging is performed using the first bed, the X gradient magnetic field coil generates a gradient magnetic field pulse for selecting a slice plane, and the second bed is moved. Y when shooting with
Gradient magnetic field pulse switching means for switching gradient magnetic field pulses generated from the X and Y gradient magnetic field coils in accordance with the bed used for imaging so that the gradient magnetic field coil generates a gradient magnetic field pulse for slice plane selection. Characteristic magnetic resonance tomography apparatus.