JPH03275041A - Magnetic resonance imaging apparatus - Google Patents

Abstract

PURPOSE:To make it possible to perform rapidly and accurately setting of an optimum condition of a high frequency pulse taking the wt. value of an examinee into consideration by connecting a means for measuring wt. of the examinee equipped on a bed with a computer system through a means for trasnmitting a signal of a measured wt. value. CONSTITUTION:As a pressure sensor 9 measuring automatically the wt. of an examinee is provided on a bed 5 of an apparatus 1 wherein a top plate 4 on which the examinee is laid down is driven, when the examinee is laid down on the top plate 4 before photographing, the value of wt. of the examinee is obtd. by means of the pressure sensor and the optimum condition of a high-frequency pulse can be rapidly set, taking the obtd. value of wt. into consideration. In addition, as the measured value of wt. is directly input in a system determining the optimum condition of the high-frequency pulse of a computer system 7 through a light transmitting line 8b, it is possible to prevent the value of wt. from input mistake and to set accurately a condition. It is therefore possible to photograph in a short time.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to nuclear magnetic resonance (NMR)
The present invention relates to a magnetic resonance imaging apparatus that applies the (Magnetic Resonance) phenomenon, and particularly relates to a bed for a magnetic resonance imaging apparatus.

(Prior Art) Nuclear magnetic resonance is a phenomenon in which atomic nuclei placed in a magnetic field resonate and absorb electromagnetic wave energy of a specific wavelength, and then emit this energy as electromagnetic waves. Magnetic resonance imaging equipment uses this phenomenon to diagnose living organisms.
The electromagnetic waves emitted from the above-mentioned atomic nuclei, especially protons, are detected and the detected signals are processed to obtain information such as atomic nuclear (proton) density, longitudinal relaxation time T1, transverse relaxation time T2, flow, chemical shift, etc. Diagnostic information such as reflected tomographic images of the subject can be obtained.

By the way, when taking a tomographic image of a subject using a magnetic resonance imaging device that utilizes such a nuclear magnetic resonance phenomenon, a high-frequency pulse for excitation is applied to a high-frequency coil, and the subject lies lying down in a static magnetic field. A high-frequency coil detects magnetic resonance signals induced from the subject. The apparent impedance of this high-frequency coil differs depending on the weight of the subject.

When the impedance of the high-frequency coil is different, the optimal strength of the high-frequency pulse (
90D pulse and 180° pulse conditions) are shifted. Therefore, prior to imaging, it is necessary to adjust the intensity of the high-frequency pulse to an optimal value depending on the weight of the subject.

To do this, the magnetic resonance imaging system technician or doctor inputs the measured weight of the subject into a system that sets the high-frequency pulse conditions before imaging, and then obtains the optimal high-frequency pulse output. There is. However, there is a possibility that an error in inputting the subject's weight value may occur, and there are problems in that the optimal high-frequency pulse conditions cannot be set quickly and that the imaging time becomes long.

In addition, a problem arises in which throughput decreases.

(Problems to be Solved by the Invention) As mentioned above, in conventional magnetic resonance imaging devices, it is necessary to take the subject's weight value into consideration when setting the optimal conditions for the high-frequency pulse for excitation, and the There are problems in that setting takes time, increases shooting time, and reduces throughput.

An object of the present invention is to provide a magnetic resonance imaging apparatus that can quickly and accurately set optimal conditions for high-frequency pulses in consideration of a subject's body weight value, and can perform imaging in a short time.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a static magnetic field generating coil that generates a static magnetic field to be applied to a subject, and a method for obtaining positional information of a site where a magnetic resonance signal is induced. A pedestal that houses a gradient magnetic field generating coil that generates a gradient magnetic field, a top plate for making the subject lie down in the space of the pedestal, a bed that moves the top plate into and out of the space of the pedestal, and a bed that emits high-frequency pulses. a high-frequency coil that detects magnetic resonance signals induced from the subject by applying a high-frequency coil; and a static magnetic field generating coil that processes the obtained magnetic resonance signals and synthesizes an image to set optimal conditions for the high-frequency pulse; , a magnetic resonance imaging apparatus comprising a gradient magnetic field generating coil, and a computer system having respective functions for controlling the operation of the bed, wherein the bed has a measuring means for measuring the body weight of the subject, and the measuring means is a magnetic resonance imaging apparatus characterized in that it is connected to a computer system via a transmission means that transmits a measured weight value as a signal.

(Function) In the magnetic resonance imaging apparatus of the present invention, the bed that drives the top plate on which the subject lies is equipped with a measuring means for automatically measuring the body weight of the subject. The body weight value of the subject is obtained by the measuring means when the subject lies down on the top plate, and the optimum conditions for the high-frequency pulse can be quickly set in consideration of the obtained body weight value. Moreover, the measured weight value is directly input as a signal to the system that determines the optimal conditions for the high-frequency pulse of the computer system via the transmission means, which prevents errors in entering the weight value and allows accurate condition settings. .

A semiconductor pressure sensor can be used as this measuring means. Further, the transmission means is preferably optical transmission in order to eliminate the influence of leakage magnetic fields from various coils in the pedestal.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. 1st
The figure is a schematic diagram showing the configuration of a magnetic resonance imaging apparatus according to an embodiment of the present invention. As shown in Figure 1, this device (1) consists of a static magnetic field generating coil that generates a static magnetic field to be applied to the subject, and a gradient magnetic field that obtains positional information of the site where the magnetic resonance signal is induced. It has a pedestal (2) that houses a gradient magnetic field generating coil for generating the magnetic field and is surrounded by a cover made of reinforced carbon fiber. The apparatus (1) also has a top plate (4) on which the subject lies in a space (3) having a circular cross section in the pedestal (2). This top plate (4) is
Driven by the bed (5), it can move freely in and out of the space (3). The height of the bed (5) can be changed by hydraulic pressure according to the physique of the subject when the subject stands on the top plate (4). This pedestal (2>, top plate (4),
The bed (5) is placed in a shield room (B) for blocking leakage magnetic fields from the pedestal (2).

This device (1) includes a high-frequency coil (not shown) that is placed in a space (3) of a pedestal (2) and that applies a high-frequency pulse to detect a magnetic resonance signal induced from a subject. A computer system (7) having a function of processing the obtained magnetic resonance signals to synthesize images, setting optimal conditions for high-frequency pulses, and controlling the operations of the static magnetic field generating coil, gradient magnetic field generating coil, and bed. has. This computer system (7) is installed in the shield room (6)
The static magnetic field generating coil, etc. in the frame (2) placed outside and inside the shield room (6) controls its operation and processes the induced magnetic resonance signals.
They are connected via a transmission line (8a). Further, this computer system (7) is connected to a pressure sensor placed on a bed (5), which will be described later, via an optical transmission line (8b).

By the way, as shown in Fig. 2, the bed (5) of this magnetic resonance imaging apparatus (1) is equipped with a pressure sensor for automatically measuring the weight of a subject lying on the top board (4). (
9) are arranged in two rows of three in the length direction of the top plate (4), a total of six in two rows. This pressure sensor (9) is connected to the top plate (
4) Convert the weight value of the subject above into an electrical signal. After this electrical signal is converted into an optical signal, the above-mentioned optical transmission line (8
b) is transmitted to the computer system (7) and input into the system for setting the optimum conditions of the high-frequency pulses for excitation (90° pulse and 180° pulse).

As shown in FIG. 3, this pressure sensor (9) has a thickness of 1.
omm crystallized glass substrate (11), this substrate (11)
This is a semiconductor pressure sensor consisting of a silicon diaphragm ( ) 3 made of a silicon single crystal with a thickness of 0.2111!1 and fixed to a silicon diaphragm ( ) via a glass binder layer (12). The substrate (11) of this silicon diaphragm (13)
) side has a diameter of 3 to form a vacuum reference pressure chamber (14).
A circular cavity with a diameter of mmφ is provided, and a pair of electrodes (15) spaced apart from each other are arranged on opposite surfaces of the silicon diaphragm (13).

This electrode (15) is connected via a lead wire (16) made of gold to a converter (not shown) that converts the electrical signal from the pressure sensor (9) into an optical signal. Moreover, the surface of this electrode (15) is coated with a protective film (17) made of 5i02.
covered with.

In this way, in a magnetic resonance imaging system, the bed that drives the top plate on which the patient lies is equipped with a pressure sensor that automatically measures the patient's weight. The body weight value of the subject is obtained by a pressure sensor when the subject is lying down on the tabletop, and the optimum conditions for high-frequency pulses can be quickly set in consideration of the body weight value obtained. Moreover, the measured weight value is directly input to the computer system that determines the optimal conditions for high-frequency pulses via the optical transmission line, which prevents errors in entering the weight value and allows accurate condition setting.

In the above embodiment, a semiconductor pressure sensor is used to measure the weight value, but any other sensor may be used as long as it converts the weight value into an electrical signal. Moreover, the number of pressure sensors can be set arbitrarily.

[Effects of the Invention] As described above, according to the present invention, it is possible to quickly and accurately set the optimal conditions for high-frequency pulses in consideration of the subject's body weight, and to obtain magnetic images that can be imaged in a short time. A resonant imaging device can also be provided.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the configuration of a magnetic resonance imaging apparatus according to an embodiment of the present invention, FIG. 2 is an enlarged side view of the bed in FIG. 1, and FIG. 3 is a diagram showing the pressure sensor in FIG. 2. FIG. DESCRIPTION OF SYMBOLS 1... Magnetic resonance imaging device, 2... Frame, 3... Vacant space, 4... Top plate, 5... Bed, 6... Shield room, 7... Computer system, 8a ...transmission line, 8b...optical transmission line, 9.
... Pressure sensor, 11 ... Substrate, 12 ... Glass binder layer, 13 ... Silicon diaphragm, 14 ... Vacuum reference pressure chamber, 15 ... Electrode, 16 ...
...Lead wire, 17...Protective film.

Claims (1)

[Claims] A pedestal for housing a static magnetic field generating coil that generates a static magnetic field to be applied to a subject and a gradient magnetic field generating coil that generates a gradient magnetic field for obtaining positional information of a region where a magnetic resonance signal is induced; A top plate for making the subject lie down in the empty space; a bed for moving the top plate into and out of the empty space of the mount;
A high-frequency coil that applies high-frequency pulses to detect magnetic resonance signals induced from the subject, processes the obtained magnetic resonance signals to synthesize an image, and sets optimal conditions for the high-frequency pulses. In a magnetic resonance imaging apparatus comprising a magnetic field generating coil, a gradient magnetic field generating coil, and a computer system having respective functions of controlling the operation of the bed, the bed has a measuring means for measuring the body weight of the subject, and the bed has a measuring means for measuring the body weight of the subject. A magnetic resonance imaging apparatus characterized in that the measuring means is connected to a computer system via a transmitting means that transmits the measured weight value as a signal.