JPS63181752A - Magnetic resonance imaging 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] [Object of the Invention] (Industrial Application Field) The present invention uses magnetic resonance phenomena to analyze a subject (usually a patient).
The present invention relates to a magnetic resonance imaging apparatus for obtaining magnetic resonance images of.

(Prior art) Magnetic resonance imaging device (hereinafter referred to as MRI device)
The method creates a uniform static magnetic field in a desired area of the subject, and uses a transmitting RF coil that creates an R)-magnetic field in a direction perpendicular to this static magnetic field to detect magnetic resonance phenomena only in a specific slice part from which a tomographic image is obtained. , and a magnetic field resonance signal (hereinafter referred to as MR multiplied signal) generated from the nucleus after the RF magnetic field is released.
is detected by a receiving RF coil. Furthermore, a composite MR multiplied signal is obtained by applying a gradient magnetic field having a linear gradient in the X'-axis direction (coordinate system rotated by θ° from the X-axis) to the static magnetic field, and this signal is subjected to Fourier transformation to slice the A CT image can be formed by rotating the X' axis of the portion within the XY plane and obtaining projection information in each direction within the XY plane.

(Problems to be Solved by the Invention) However, in conventional MRI apparatuses, the subject is inserted into a cylindrical body formed by static magnetic field coils, gradient magnetic field coils, etc. This poses the problem of giving the subject a sense of fear of being inserted into the body.

SUMMARY OF THE INVENTION The present invention aims to eliminate the above-mentioned drawbacks, and an object of the present invention is to provide a magnetic resonance imaging apparatus that reduces the fear of a subject.

[Structure of the Invention] (Means for Solving the Problems) The present invention comprises a pair of magnetic poles arranged opposite to each other with a predetermined interval, and a pair of magnetic poles arranged oppositely between the magnetic poles. A static magnetic field generator that generates a uniform static magnetic field, and an opening that is arranged between the pair of magnetic poles, has a hollow interior, and communicates with the outside in a direction in which the subject is inserted and a direction perpendicular thereto. A gradient magnetic field generation unit that generates a gradient magnetic field to be superimposed on the static magnetic field, and a pair of loop coils are arranged opposite each other at a predetermined interval in the body axis direction of the subject, and are capable of transmitting RF pulses and magnetic resonance signals. It has a transmitting/receiving coil that receives the information.

(Function) According to the static magnetic field generating section, gradient magnetic field generating section, and transmitting/receiving coil described above, it is possible to form an open type device, and the subject is not given a feeling of fear of being inserted into an open place or a dark place.

(Example) Hereinafter, the present invention will be specifically explained with reference to Examples.

1(a), (b), (C) and FIG. 2 show an embodiment of the present invention.

As shown in FIG. 1 (a), the static magnetic field generating section 1 in the present embodiment device has a horizontal C-shape in which a pair of magnetic poles 2 and 3 are arranged facing each other with a predetermined interval. A device that forms a uniform static magnetic field between them is used, for example, one consisting of an iron yoke and a magnet.

The magnet may be a permanent magnet, a normal conducting magnet, or a superconducting magnet. The direction of the static magnetic field formed between the pair of magnetic poles 2 and 3 is in the direction of arrow 4, and the subject P is placed in this static magnetic field.

In addition, the gradient magnetic field generating section that generates the gradient magnetic field superimposed on the static magnetic field is formed in a rectangular shape, as shown by 5 in FIG. gradient magnetic field coils 1a, 1b, second gradient magnetic field coils 2a, 2b formed in a circular shape and generating gradient magnetic fields in the X direction, and third gradient magnetic field coils 2a, 2b formed in a rectangular shape and generating gradient magnetic fields in two directions. It has magnetic field coils 3a and 3b.

Each coil is molded with resin or the like as shown in FIG. 2, and as a result, the gradient magnetic field generating section 5 is a structure consisting only of the sides of the hexahedron, and is exposed to the outside in the specimen insertion direction 7 and the direction orthogonal thereto. A communicating opening is formed.

Generally speaking, a saddle-type coil or a solenoid-type coil is usually used as a transmitting/receiving coil for transmitting RF pulses and receiving MR multiplied signals, but using such coils impairs the sense of openness. As shown in FIG. 1(C), the first and second loop coils 6 are arranged at a predetermined interval in one direction along the body axis 5 of the subject P.
A and 6b are arranged facing each other. 1st. Second loop coil 6
a and 6b are collectively referred to as loop bare coils. The sensitivity patterns of this loop bare coil are shown in FIGS. 3 and 4.

Fig. 3 shows the axial (plane perpendicular to the body axis) pattern, and Fig. 4 shows the sagittal and coronal (planes parallel to the body axis) patterns. The sensitivity range of this loop bare coil is widest when the ratio of diameter (2D) to coil span (L) is 2=1. Further, each of the loop bare coils can be molded together with the third gradient @field coils 3a and 3b in the gradient magnetic field generating section 5, and in this way, the loop bare coils can be attached so as not to be visible from the outside. .

As described above, in this embodiment, the static magnetic field generating section 1, the gradient magnetic field generating section 5. Loop bare coil (6a.

6b), it is an open type and does not give a sense of fear to the subject.

Note that the present invention is not limited to the above embodiments. For example, the second gradient magnetic field coils 2a, 2b and the loop pair coils (6a, 6b) are formed into an angular shape, and the opening in the subject insertion direction 7 and the direction perpendicular thereto is enlarged to improve the sense of openness. You may try to do so.

[Effects of the Invention] As described in detail above, according to the present invention, it is possible to provide an MRI apparatus that reduces a subject's sense of fear.

[Brief explanation of the drawing]

Figures 1 (a), (b), (C) and 2 are perspective views showing one embodiment of the present invention, and Figures 3 and 4 show sensitivity patterns of the loop bare coil in this embodiment. It is a diagram. DESCRIPTION OF SYMBOLS 1... Static magnetic field generation part, 2.3... Pair of magnetic poles, 5... Gradient magnetic field generation part, 6a, 6b... Transmission/reception coil. Agent Patent Attorney Nori Chika Ken Shu
Norio Ogo 71

Claims (1)

[Claims] In a magnetic resonance imaging apparatus that forms a magnetic resonance image of a subject placed in a uniform static magnetic field based on magnetic resonance signals from the subject, a pair of magnetic poles are arranged facing each other with a predetermined interval. a static magnetic field generator that forms a uniform static magnetic field between the magnetic poles; and an opening that is disposed between the pair of magnetic poles, has a hollow interior, and communicates with the outside in a direction in which the subject is inserted and a direction perpendicular thereto. A gradient magnetic field generating section is provided and generates a gradient magnetic field superimposed on the static magnetic field, and a pair of loop coils are arranged facing each other at a predetermined interval in the body axis direction of the subject, and the RF pulse is transmitted. and a transmitting/receiving coil that receives magnetic resonance signals.