JPH02243132A - Magnetic resonance imaging apparatus - Google Patents

Abstract

PURPOSE:To obtain the title apparatus having the degree of freedom of positioning in a body lateral direction by constituting said apparatus so that a bed on which an examinee is placed is rotated in the direction crossing the generation direction of a static magnetic field at a right angle. CONSTITUTION:Permanent magnets 5A, 5B are mounted to the inner surfaces of the upper body 4A and lower body 4B of the magnetic circuit 4 having an oblong annular cross-section constituting a gantry 3 and a bed 6 is arranged on the rotary drive mechanism 7 provided on a floor 8 so as to confront to the opening part of the cavity 3A of the gantry 3. An examinee is placed on the slide top plate 6A of the bed 6 to be introduced into the cavity 3A and, when the rotary drive mechanism 7 is driven in this state, the top plate 6A can be moved in an oscillating manner to make it possible to set the specific position of the examinee in the body lateral direction to a diagnosable region above a static magnetic field generating space. Further, the specific position of the examinee in the body axis direction thereof can be set to the diagnosable region above the static magnetic field generating space by moving the top plate of the bed 6 and the specific position of the examinee in the body thickness direction thereof can be set to said region by adjusting the height of the bed 6. Therefore, a magnetic resonance imaging apparatus having the degree of freedom of positioning in the body lateral direction is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Aspects of the invention] (Industrial application field) The present invention is directed to magnetic resonance (MR)
The present invention relates to a magnetic resonance imaging apparatus that obtains morphological information such as slice images of a subject (living body) and functional information such as spectroscopy using the phenomenon (sonance).

(Prior art) Magnetic resonance is a phenomenon in which an atomic nucleus with non-zero spin and magnetic moment placed in a static magnetic field resonantly absorbs and emits only electromagnetic waves of a specific frequency. The angular frequency ω shown in (ω.−2πν0.ν0
; Larmor frequency).

ω0″γH.

Here, γ is the gyromagnetic ratio specific to the type of atomic nucleus,
Further, HO is the static magnetic field strength.

An apparatus that performs biological diagnosis using the above-mentioned principle processes the electromagnetic waves of the same frequency as the above induced after the above-mentioned resonance absorption, and calculates the nuclear density, longitudinal relaxation time TI, transverse relaxation time T2. Diagnostic information that reflects information such as flow and chemical shift, such as slice images of a subject, can be obtained non-invasively.

Collecting diagnostic information by magnetic resonance can excite all parts of a subject placed in a static magnetic field and collect signals, but there are limitations in the equipment configuration and clinical requirements for imaging images. Therefore, in an actual device, a specific part is excited and its signal is collected.

In this case, the specific region to be imaged is generally a sliced region with a certain thickness;
Magnetic resonance signals (MR multiplied signals) of echo signals and FID signals from this slice site are collected by performing a data encoding process many times, and these data groups are subjected to image reconstruction processing using, for example, a two-dimensional Fourier transform method. By doing so, an image of the specific slice region is generated.

Such magnetic resonance imaging apparatus can be divided into vertical magnetic field type and horizontal magnetic field type depending on the form of generating the static magnetic field strength Ho. Also, depending on the magnitude of the magnetic field strength etc., electromagnetic coils such as Helmtz coils and solenoid coils are used. The structure uses electromagnets and permanent magnets as appropriate.

Furthermore, since the body axis of a subject placed on a bed is parallel to the horizontal direction, in the vertical magnetic field method, the static magnetic field and the body axis direction are orthogonal, and in the horizontal magnetic field method, the static magnetic field and the body axis direction are They are parallel. In general, the static magnetic field strength is 2
000 gauss is a perpendicular magnetic field method using permanent magnets or normally conducting magnets, and the static magnetic field strength is 500 gauss.
For those with a magnetic field strength of about 0 to 10,000 Gauss, a horizontal magnetic field method using a normal conducting magnet is used, and the static magnetic field strength is 1,000 Gauss.
For those above about 0 Gauss, a horizontal magnetic field method using superconducting magnets is used.

FIG. 2 is a perspective view showing the configuration of a horizontal magnetic field type magnetic resonance imaging apparatus, in which a magnet for generating a static magnetic field consisting of a normal conducting magnet or a superconducting magnet is installed in the gantry 1.

A gradient magnetic field coil, a transmitting/receiving coil, etc. are built-in, and these are installed in the cylindrical patient introduction cavity IA formed in the same gantry 1.
A superimposed magnetic field is generated using a static magnetic field, a gradient magnetic field, and an excitation high-frequency magnetic field.

A bed 2 is installed facing the opening of the cylindrical cavity IA of the gantry 1, and a test subject (not shown) is placed on the slide top plate 28 of this bed 2. It can be introduced into the IA and positioned in the superimposed magnetic field region within the cylindrical cavity IA.

(Problem to be Solved by the Invention) With such a water V magnetic field system, positioning and setting is possible in the diagnostic magnetic field area, which is a spherical space with a diameter of several tens of centimeters or less that can be used for diagnosis in the superimposed magnetic field area. The area of the subject that can be examined is the area in the direction of movement of the slide top plate 2A, that is, the area in the body axis direction of the subject. This means that although any region can be set in the body axis direction (Z-axis direction in the figure), there is no degree of freedom in the body width direction (X-axis direction in the figure). Note that an arbitrary area can be set in the body thickness direction (Y direction in the figure) by adjusting the height of the bed 2 by: J3.

Therefore, an object of the present invention is to provide a magnetic resonance imaging apparatus that has a degree of freedom in positioning in the body width direction.

[Structure of the Invention] (Means for Solving the Problems) The present invention has a structure in which the following means are taken to solve the above problems and achieve the objects.

That is, the present invention provides a magnetic resonance imaging apparatus having a static magnetic field generating magnet that generates a static magnetic field in a direction perpendicular to the body axis of the subject, which is placed horizontally, in which the subject is placed. The present invention is characterized in that the bed for the magnetic field is configured to rotate in a direction perpendicular to the direction in which the static magnetic field is generated.

(Function) According to such a configuration, by rotating the bed, a specific position in the body width direction of the subject can be set in the diagnosable region in the static magnetic field generation space.

(Example) An example of a magnetic resonance imaging apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing a vertical magnetic field type magnetic resonance imaging apparatus of this embodiment using, for example, a permanent magnet, which has nine degrees of freedom in positioning in the body axis direction, the body thickness direction, and the body width direction.

As shown in FIG. 1, permanent magnets 5A and 5B are attached to the inner surfaces of an upper body 4A and a lower body 4B of a magnetic circuit 4 having a horizontally long annular cross section and forming a gantry 3. A diagnosable magnetic field region is generated in the space facing 5B and 5B. In the opposing space, gradient magnetic field coils, transmitter/receiver coils, etc. (not shown) are installed, and these are placed inside the subject introduction cavity 3A formed in the same gantry 3.
It is designed to generate a superimposed magnetic field of a static magnetic field, a gradient magnetic field, and an excitation high-frequency magnetic field.

A bed 6 is arranged facing the opening of the cavity 3A of the gantry 3, and this bed 6 is installed on a rotational drive mechanism 7 installed on the floor 8. In this case, the rotating shaft 6B in the bed 6
is located on the side not facing the opening. A subject (not shown) is placed on the slide top plate 6A of the bed 6, and the subject can be introduced into the cavity 3A and positioned in the superimposed magnetic field region within the cavity 3A, that is, in the body axis direction ( Any area can be set in the Z-axis direction (illustrated). In addition, in FIG. 1, the body thickness direction (Y direction in the figure) is
By adjusting the height of the bed 6, any area can be set.

According to this configuration, by driving the rotational drive mechanism 7, the bed 6 (top plate 6A) can be oscillated in the direction H in the figure, so that the body of the subject placed on the top plate 6A can be moved. A specific position in the width direction can be set in a diagnosable region on the static magnetic field generation space.

Furthermore, by moving the top plate of the bed 6, a specific position in the body axis direction of the subject can be set in a diagnosable region in the static magnetic field generation space. Furthermore, by adjusting the height of the bed 6, a specific position in the body thickness direction of the subject can be set in a diagnosable region in the static magnetic field generation space.

By appropriately combining the rotation of the bed 6 and the height adjustment of the top plate movement 1, any position of the subject can be set in the diagnosable region in the static magnetic field generation space.

Note that the rotational drive mechanism 7 may be of an electric type using a motor or a hydraulic type, and of course may be configured to be manually rotated. Moreover, instead of rotating the entire bed 6 (it is also possible to rotate only the top plate 6A), it is also possible to use an electromagnet.

The invention can be modified in various ways without departing from the gist of the invention.

[Effects of the Invention] As described above, in the present invention, the bed on which the subject is placed is configured to rotate in the direction perpendicular to the direction in which the static magnetic field is generated. A specific position in the body width direction of the examiner can be set in a diagnosable region in the static magnetic field generation space.

Therefore, according to the present invention, it is possible to provide a magnetic resonance imaging apparatus that has a degree of freedom in positioning in the body width direction.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an embodiment of a magnetic resonance imaging apparatus according to the present invention, and FIG. 2 is a perspective view of a horizontal magnetic field type magnetic resonance easing apparatus. 3... Gantry, 3A... Opening, 4... Magnetic circuit, 5A, 5B... Permanent magnet 6... Bed, gA...
・Top plate, 6B...rotation shaft, 7...rotation drive mechanism. Figure 1 Applicant's agent Patent attorney Takehiko Suzue

Claims (1)

[Claims] In a magnetic resonance imaging apparatus having a static magnetic field generating magnet that generates a static magnetic field in a direction perpendicular to the body axis of a subject placed horizontally, the bed on which the subject is placed is A magnetic resonance imaging apparatus characterized by having a configuration that rotates in a direction perpendicular to the direction in which a static magnetic field is generated.