JP2650955B2 - Inspection equipment using nuclear magnetic resonance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention utilizes nuclear magnetic resonance (hereinafter referred to as NMR),
It relates to a device for inspecting the internal structure of a subject,
The present invention relates to an inspection apparatus using nuclear magnetic resonance suitable for detecting an NMR signal.

[Conventional technology]

2. Description of the Related Art Conventionally, an X-ray CT or an ultrasonic imaging apparatus has been widely used as a device for nondestructively inspecting an internal structure of a human body such as a head and abdomen. In recent years, attempts to perform a similar inspection using nuclear magnetic resonance development have been successful, and it has become clear that information that cannot be obtained with an X-ray CT or an ultrasonic imaging apparatus can be obtained. In an inspection apparatus using nuclear magnetic resonance development, it is necessary to separate and identify a signal from an inspection object corresponding to each part of the object. As one of the methods, there is a method in which a gradient magnetic field is applied to an inspection object to change the static magnetic field in which each part of the object is placed, thereby obtaining a position information by changing a resonance frequency or a phase encoding amount of each part. .

For the basic principle, see Journal of Magnetics Resonance (J. Magn. Reson.), Vol. 18, No. 6
On page 9 (1975) or the Journal of the Physics of Medicine and Biology (Phys. Med. & Biol.)
It is reported in Vol. 25, p. 751 (1980).

Now, in such a method, improving the image quality is indispensable for improving the diagnostic performance of the apparatus. One method for improving image quality is to increase the S / N ratio of NMR signals, and various methods have been proposed so far. One of the methods is to use two sets of high-frequency coils orthogonal to each other for receiving a high-frequency magnetic field. This coil is usually QD
It is called a coil, and has features that the 3bBSN ratio is improved as compared with a single coil, and the spatial uniformity when transmitting and receiving a high-frequency magnetic field is also improved. The details are described in Holt et al. In The Journal of Magnetic Resonance, Vol. 54, pp. 324-327 (1983).

[Problems to be solved by the invention]

However, the above-mentioned prior art can be applied to a coil including the entire head or thorax and abdomen, but cannot be applied to a surf coil which is often used for photographing only the vicinity of the body surface.

An object of the present invention is to configure a surf coil as a QD coil for an organ located off the center of the body, such as the heart and the flank.

[Means for solving the problem]

The above object is achieved by arranging two sets of surf coils perpendicular to each other and bringing them into close contact with the end of the body.
That is, an inspection apparatus using nuclear magnetic resonance, comprising: magnetic field generating means for each of a static magnetic field, a gradient magnetic field, and a high-frequency magnetic field; and signal detecting means for detecting a nuclear magnetic resonance signal from an inspection object. , The signal detecting means is composed of two facing surf coils and one surf coil coupled to each of the two surf coils so as to be variable in angle. It is characterized in that the gains of the high-frequency amplifiers respectively connected to the two surf coils and the one surf coil coupled to the two surf coils are different. Further, two facing surf coils and one surf coil coupled to the two surf coils are used as a quadrature signal detection coil and a quadrature phase transmitting coil.

[Action]

That is, in order for two sets of coils to operate as QD coils, the coupling between the coils, that is, the mutual inductance, needs to be zero. Therefore, as shown in FIG. 1, two sets of surf coils 1, 2, and 3 are used to surround the target object 4, and the coils 1 and 2 are wired so as to have the same polarity sensitivity in the y-axis direction. For example, since the coils 1 and 2 have opposite polarities with respect to the coil 3 having sensitivity in the x-axis direction, the effects cancel each other. However, since the coils 1 and 2 operate with the same polarity for the NMR signal, they are added to each other, resulting in an increase in the signal amount. As a result, coil 1,
2 does not have mutual inductance with the coil 3 and operates independently of each other, so that a QD configuration can be adopted. In FIG. 1, it is assumed that the static magnetic field is applied in the Z-axis direction orthogonal to any of the two sets of coils.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 2 shows an embodiment in which the surf coils 1, 2, and 3 are connected by a movable section 5 and the angle θ formed by both coils is variable.
The movable part 5 has a hinge structure, and the angle θ
And the coil 3 can be set at an angle at which the mutual inductance of the coil 3 becomes minimum. Each coil is provided with a matching circuit 6 for tuning and impedance matching, and the output thereof is supplied to a high frequency amplifier (not shown) through a coaxial cable 7.
It is connected to the.

FIG. 3 shows an embodiment in which the surf coil is curved so as to be more suited to the shape of the subject. 2 and 3, the arm can be passed through the hole of the coil 3 so that the coil can be brought into closer contact with the inspection section than in the case of the above embodiment. The coil
When the efficiencies of the coils 1 and 2 and the coil 3 are different, it is necessary to make the gains of the high-frequency amplifiers connected to the two different and to match the efficiencies as a whole.

〔The invention's effect〕

According to the present invention, a surf coil can be formed into a QD coil for a specific organ in the body such as the heart, and the SN of the NMR signal or the transmission efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a view for explaining the principle of the present invention, and FIGS. 2 and 3 are perspective views of a coil showing an embodiment of the present invention.

Claims (2)

(57) [Claims] 1. An apparatus comprising: magnetic field generating means for generating a static magnetic field, a gradient magnetic field, and a high-frequency magnetic field; and signal detecting means for detecting a nuclear magnetic resonance signal from an object to be inspected. In the inspection apparatus used, the signal detecting means includes two opposing surf coils, and one surf coil coupled to each of the two surf coils so that an angle between the surf coils is variable. Wherein the gains of the high-frequency amplifiers respectively connected to the two facing surf coils and the one surf coil coupled to the two surf coils are made different. Inspection device using nuclear magnetic resonance. 2. The two facing surf coils,
2. The nucleus according to claim 1, wherein said one surf coil coupled to said two surf coils is used as a quadrature signal detection coil and a quadrature phase transmission coil. Inspection device using magnetic resonance.