JPH04146724A - Permanent magnet type magnetic resonance imaging device - Google Patents

Abstract

PURPOSE:To carry out the photographing with high image quality without giving pains to an inspected person, in the photographing for four trunk bodies, by installing an auxiliary ceiling plate device between the first and second holding bodies. CONSTITUTION:Supporting bodies 21A and 21B are installed in the vicinity of a lower part pole piece 14, and auxiliary ceiling plates 22A and 22B which can be shiftable in parallel in the direction of arrow are installed for the supporting plates 21A and 21B. When the auxiliary ceiling plate 22A or 22B is pulled out from a static magnetic field generating space, an inspected person P can position his arm in the magnetic field uniform region of the static magnetic field generating space at an easy posture, by opening his arm, setting his trunk body on the auxiliary ceiling plate 22A. Accordingly, photographing can be carried out with high image quality without giving pains to the inspected person, in the photographing for four trunk bodies.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to magnetic resonance (MR)
The present invention relates to a magnetic resonance imaging apparatus that obtains morphological information and functional information such as spectroscopy of a subject by using the phenomenon (sonance), and particularly relates to a type of magnetic resonance imaging apparatus that obtains a static magnetic field using a permanent magnet.

(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 (ωo−2πν., .

; Larmor frequency) ν It resonates with me.

ω〇−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 electromagnetic waves of the same frequency as above that are induced after the above-mentioned resonance absorption, and calculates nuclear density, longitudinal relaxation time T1. Transverse relaxation time T2. Diagnostic information that reflects information such as flow and chemical shift, such as slice images of a subject, is obtained non-invasively.

Collecting diagnostic information using 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 aspects of imaging images. Due to this request, the actual device is designed to excite a specific region and collect its signals.

Considering the equipment configuration, there are superconducting magnet type, normal conducting magnet type, and permanent magnet type devices depending on the form of the static magnetic field generator.Recently, high strength magnets have appeared which have the advantage of low operating cost. Due to certain circumstances, permanent magnet type devices are in the spotlight.

FIG. 3 is a sectional view of the main body of a permanent magnet type magnetic resonance imaging apparatus, and shows a so-called longitudinal magnetic field system. Third
As shown in the figure, the upper permanent magnet 12 to which the upper pole piece 11 is attached is attached to the upper yoke 13, and the lower permanent magnet 15 to which the lower pole piece 14 is attached is attached to the lower yoke 16, and, Upper yoke 1
3 and the lower yoke 16 are connected by a plurality of side yokes 17 (the four corners are connected in the illustration).
. Here, upper pole piece 11 and lower pole piece 1
The space facing 4 is a static magnetic field generation space. Also,
Upper pole piece 11. Upper permanent magnet 12. Upper yoke 13. Lower pole piece 14. Lower permanent magnet 15. Lower yoke 16. The side yoke 17 constitutes a closed magnetic circuit.

In addition, the upper pole piece 11 and the lower pole piece 14
A gradient magnetic field coil (not shown) is provided, and a transmitting coil 18 and a receiving coil 19 are arranged in the static magnetic field generation space.

A subject (not shown) is inserted into the static magnetic field generation space, and the subject is inserted through a bed top 20 placed in the space. Here, the transmitting coil 18 in the vertical magnetic field method. A solenoid coil can be used as the receiving coil 19, and high sensitivity reception is possible.
It has been advantageous.

(Problem to be Solved by the Invention) As a characteristic of permanent magnet type magnetic resonance imaging apparatuses such as the vertical magnetic field method, in addition to operating costs, electromagnet type magnetic resonance imaging using a cylindrical electromagnet is There is also the advantage that the opening can be made wider when introducing the subject P into the uniform magnetic field space compared to the device. but,
This is the head.

This is especially true when photographing the torso,
When photographing limbs, such as arms and legs, the subject P has to hold an awkward posture, causing pain.

On the contrary, in order not to take an unreasonable posture, a spatial region with poor magnetic field uniformity is sometimes used for photographing, and good images may not be obtained.

The above will be explained below with reference to the drawings.

That is, FIGS. 4 and 5 illustrate the photographing situation with the upper yoke 13 removed from FIG. 3. As shown in Figure 4, in the case of head photography, the top plate 20
The subject P rides on the top plate 20 so that the body axis is in the longitudinal direction of
．． By inserting the head to be photographed into 19, photographing can be carried out without difficulty.

On the other hand, as shown in FIG.
This resulted in subject P being required to maintain an unreasonable posture.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a permanent magnet type magnetic resonance imaging apparatus that makes it possible to perform high-quality imaging of limbs without causing pain to the subject.

[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 first
A holding body and a second holding body to which a second permanent magnet part is attached are connected by a plurality of holding columns, and a magnetic resonance imaging device is provided between the first permanent magnet and the second permanent magnet. In the permanent magnet device for a magnetic resonance imaging apparatus, the permanent magnet device generates a static magnetic field and forms a magnetic closed circuit by the first holding body, the second holding body, and the plurality of holding columns. The present invention is characterized in that an auxiliary top plate device is provided between the holding body and the second holding body.

(Function) According to this configuration, in the case of limb imaging, the subject places the arm, etc. to be imaged on the auxiliary top plate, and places the arm, etc. to be imaged in a uniform magnetic field area of the static magnetic field generation space in a comfortable posture. Can be positioned.

(Example) An example of a permanent magnet device for a magnetic resonance imaging apparatus according to the present invention will be described below with reference to FIGS. 1 and 2. As shown in FIGS. 1 and 2, in the device of this embodiment, a support 21A is provided near the edge of the lower pole piece 14,
21B is provided, and auxiliary top plates 22A, 22B are provided which are movable parallel to the supports 21A, 21B in the direction of the arrow in the figure.

According to the apparatus of this embodiment configured as described above, when the auxiliary top plate 22A or 22B is housed in the static magnetic field generation space as shown by the broken line in the figure, imaging is performed in the same manner as in the state shown in FIG. be able to.

Furthermore, when the auxiliary top plate 22A or 22B is pulled out from the static magnetic field generation space, the subject P can easily place his/her torso on the auxiliary top plate 22A and open his/her arms, as shown in FIG. Moreover, the arm can be positioned in a uniform magnetic field region of the static magnetic field generation space in a comfortable posture.

The present invention is not limited to the above-mentioned embodiments, but can take various forms with respect to the shape of the auxiliary top plate, the structure of the support body, the number of installations thereof, the installation position, etc.

[Effects of the Invention] As described above, in the present invention, the auxiliary top plate device is provided between the first holder and the second holder, so that when photographing the limbs, the subject can It is possible to position the arm or the like to be photographed in a uniform magnetic field region of the static magnetic field generation space in a comfortable posture by placing it on the auxiliary top plate.

Therefore, according to the present invention, it is possible to provide a permanent magnet type magnetic resonance imaging apparatus that makes it possible to perform high-quality imaging of limbs without causing pain to the subject.

[Brief explanation of drawings]

Fig. 1 shows the configuration of a permanent magnet magnetic resonance imaging apparatus according to the present invention, and is a plan view with the upper yoke removed, Fig. 2 is a front view of the same embodiment, and Fig. 3 is a conventional The front view of the example device, and FIGS. 4 and 5 show the photographing situation of the conventional example device, and are plan views with the upper yoke removed. 11... Upper pole piece, 12... Upper permanent magnet, 13... Upper yoke, 14... Lower pole piece, 15... Lower permanent magnet, 16... Lower yoke, 1
7...Side yoke, 18...Transmission coil, 19.
... Receiving coil, 20... Bed top plate, 21A. 21B--Support, 22A, 22B--Auxiliary top plate. Applicant's Representative Patent Attorney Takehiko Suzue Figure 4 Figure 4 Flash Figure

Claims (1)

[Claims] A first holding body to which the first permanent magnet part is attached and a second holding body to which the second permanent magnet part is attached are connected by a plurality of holding columns, and the first permanent magnet and the second holding body are connected by a plurality of holding columns. Magnetic resonance imaging in which a static magnetic field for magnetic resonance imaging is generated between a permanent magnet and a magnetic closed circuit is formed by the first holding body, the second holding body, and the plurality of holding columns. A permanent magnet magnetic resonance imaging apparatus, characterized in that an auxiliary top plate device is provided between the first holder and the second holder.