JPS6226052A - Mri apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to an MRI (nuclear magnetic resonance imaging) apparatus.

BACKGROUND OF THE INVENTION Conventionally, in an MRI apparatus, a cylindrical static magnetic field magnet 12, which forms a horizontal static magnetic field as shown in FIG. 3, is placed horizontally. A region is formed. Therefore, the gantry 11 is also cylindrical, and the subject 5 is inserted into the tunnel portion 13 along the body axis from the direction of the head or feet. To perform this insertion, the head device 6 moves the top plate 7 in the left-right direction in the figure, and moves the subject 5 in the body axis direction.

Problems to be Solved by the Invention However, the above-mentioned cylindrical static magnetic field magnet 1
2, it is difficult to efficiently shield the return flux that is formed on the outside.Therefore, the static magnetic field is generally shielded by shielding the entire sublayer. In addition, in the long uniform magnetic field region formed in the tunnel part 13 of the gantry 11,
Since the subject 5 must be moved along the body axis, the total length of the gantry 11 and bed device 6 must be at least about 5 m. For these reasons, conventional MRI apparatuses have the problem of requiring a large installation area.

In particular, if the depth of the static magnetic field region is long, the top plate 7
Since the moving distance becomes longer, the installation area must become larger.

Furthermore, in conventional MRI apparatuses, the subject 5 is inserted into the long tunnel part 13 of the gantry 11, which may give unnecessary anxiety to the subject 5, and the examiner may have to directly monitor the condition of the subject 5. There is also the problem that it cannot be observed.

This invention provides efficient static magnetic field shielding, does not make the patient feel anxious, makes it easy to observe the patient's condition, and requires less installation space, resulting in overall miniaturization. The purpose is to provide a possible MRr device.

Means for Solving the Problems The MRI apparatus according to the present invention includes magnet means arranged above and below that form a vertical static magnetic field, and a C-type flux path means that connects these magnet means and passes return flux. The present invention is characterized in that an opening is provided in the lateral direction where the C-shaped flux path means does not exist, and bed means on which the subject lies is placed in front of the opening.

Since the return flux passes through the C-type flux path,
Efficient magnetic shielding can be performed. Furthermore, since an opening is provided in the lateral direction and a bed is placed in front of the opening, the subject can be placed between the magnets arranged above and below from here.

Embodiment In FIGS. 1 and 2, the gantry 1 is generally C-shaped and has an opening 2 in the lateral direction. Inside this gantry l, magnets 3 for static magnetic fields are arranged above and below the open part 2, and a vertical uniform static magnetic field region is formed within the open part 2 by these magnets. A C-shaped yoke 4 that connects these magnets 3 to each other is further arranged within the gantry l. This yoke 4 is made of a magnetic material such as iron, is formed by the magnet 3, and functions as a black path through which the return flux passes.

On the other hand, the bed device 6 is arranged in front of the open section 2 of the gantry I. This bed device 6 has a top plate 7 on which the subject 5 is placed.
can be moved laterally. The top plate 7 can be moved in the left-right direction in FIG. 1 in order to position the imaging site in the axial direction of the subject 5, and can also be moved in the vertical direction. It looks like this.

In this configuration, a static magnetic field is formed perpendicularly between the magnets 3 arranged above and below, and its return flux passes through the C-shaped yoke 4 on the side, so that effective magnetic shielding can be achieved.

The subject 5 is placed within the uniform magnetic field area formed within the open portion 2 of the gantry l in the following manner. First, the subject 5 is placed on the descending top plate 7, and then raised to a predetermined height. Then, the top plate 7 is moved in the direction of the body axis of the subject 5 so that the region to be examined of the subject 5 corresponds to the uniform magnetic field region, and when this positioning is completed, the top plate 7 is moved in the direction perpendicular to the body axis. Move the board 7 and place the patient 5
into the opening 2.

Therefore, since the uniform static magnetic field region is open,
The examinee 5 inserted therein will not feel unnecessary anxiety, and the examiner can directly observe the condition of the examinee 5 through the open part 2. Also.

Since the subject 5 is moved laterally and inserted into the static magnetic field region, the installation area is small, approximately 3 m in the horizontal direction and approximately 2 m in the depth direction, as shown in the figure.

Note that the magnet 3 may be of any type, such as a normal conductive type, a superconducting type, or a permanent magnet type.

Effects of the Invention According to this invention, a static magnetic field is formed perpendicularly between the magnets arranged above and below, and its return flux passes through the C-shaped flux path means on the side, so it can be used effectively even in a limited space. Magnetic shielding can be performed. Furthermore, the test subject does not feel uneasy, and the test subject can be easily observed. Furthermore, the installation area is small, and the entire structure including the gantry and bed device can be downsized.

[Brief explanation of drawings]

FIG. 1 is a schematic front view of an embodiment of the present invention, FIG. 2 is a schematic side view of the same embodiment, and FIG. 183 is a schematic front view of a conventional example.

Claims (2)

[Claims] (1) It has magnet means arranged above and below that form a vertical static magnetic field, and a C-type flux path means that connects these magnet means and passes return flux,
An MRI apparatus characterized in that an opening is provided in the lateral direction where the C-type flux path means does not exist, and bed means on which a subject lies is arranged in front of the opening. (2) The bed means slides the subject in a direction perpendicular to the body axis of the subject and places the subject from the opening side between the magnet means arranged above and below. MRI according to claim 1, characterized in that:
Device.