JPS62144644A - Nuclear magnetic resonance tomographic 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] [Industrial Field of Application] This invention creates a tomographic image of an object to be measured, such as a human body, based on nuclear magnetic resonance signals from the object.

The present invention relates to a nuclear magnetic resonance tomography device that displays images.

[Conventional technology]

In general, a nuclear magnetic resonance tomography apparatus (hereinafter referred to as NMR) used as a medical diagnostic device includes a static magnetic field generating means consisting of a permanent magnet, a static magnetic field coil, etc. that forms a static magnetic field, and a static magnetic field generating means. a gradient magnetic field coil that applies a gradient magnetic field to a human body as a measured object disposed in a static magnetic field; a high-frequency coil for high-frequency generation and detection that applies a high-frequency magnetic field to the human body and detects an NMR signal from the human body; It is comprised of a control means for controlling the gradient direction of the gradient magnetic field and the frequency of the high-frequency magnetic field, and an image processing means for processing the NMR signal to create a tomographic image of the human body based on the signal and displaying it on a CRT.

Then, at the same time, a gradient magnetic field in a predetermined gradient direction in an arbitrary measurement cross section is applied to the human body disposed in the static magnetic field by the static magnetic field generating means based on the control of the control means by the gradient magnetic field coil. A high-frequency magnetic field of a predetermined frequency is applied based on the control of the control means by the high-frequency coil, and the NMR signal of the atomic nucleus in the measurement section is detected by the high-frequency coil, and the detected NMR signal is detected by the high-frequency coil.
The i R signal is processed by the image processing means to output a tomographic image signal indicating the distribution of atomic nuclei in the measured cross section of the human body, and the tomographic image of the measured cross section of the human body is displayed on the CRT.

However, with this type of NIVl, R tomographic imaging device,
Despite fluctuations in the chest and abdomen caused by the human body's breathing movement, the obtained tomographic image of the human body fluctuates because the timing of applying gradient magnetic fields and high-frequency magnetic fields is not synchronized with the cycle of the human body's breathing movement. The problem is that the tomographic image becomes distorted, blurred, and even produces striped false images called artifacts.

Conventionally, an impeller was installed near the nostrils of the human body, and respiratory movements were detected by the rotation of the impeller caused by exhalation. This is not always the same; for example, the state of the bulge in the chest and abdomen at the start of exhalation is different when inhaling deeply and when inhaling shallowly. Therefore, it is important to accurately detect the breathing movement of the human body from the rotation of the impeller. I can't do it,
The timing of applying gradient magnetic fields and high-frequency magnetic fields is inaccurately synchronized with the cycle of human breathing motion, and it is impossible to prevent blurring and artifacts in tomographic images.

On the other hand, as described in Japanese Patent Application Laid-Open No. 60-77744,
In an NMR tomographic imaging device, a light transmitting optical fiber guides light from a light source to a displaced part due to breathing movement of a human body, and a light receiving fiber guides light reflected by the human body emitted from the light transmitting optical fiber to an optical receiver. It has been considered to provide a signal processing section that obtains a synchronization signal synchronized with the fluctuations caused by human body respiration from the reflected light received by the optical receiver.

Furthermore, as described in ``Improvement of Abdominal Image Quality Using a Breathing Cate'' on page 713 of the Proceedings of the 41st Society of Radiological Technology, a fan-shaped laser beam is irradiated from the outside of the device to the abdomen approximately parallel to the human body. It is also being considered that an optical position sensor detects the movement of the laser beam passing through a light-shielding slit fixed to the abdomen of the human body, and that a synchronized pulse signal is generated based on the respiratory movement waveform of the human body obtained from the output of the optical position sensor. .

[Problem that the invention attempts to solve]

However, the method described in the above publication obtains a synchronization signal by receiving the reflected light from the human body using a light-receiving optical fiber, so the synchronization signal contains errors, making it difficult to accurately detect the breathing movement of the human body. Therefore, there is a problem in that it is not possible to always obtain tomographic images of the human body in the same state.

Furthermore, the method described in the above-mentioned manuscript requires a laser as a light source, and the laser beam is irradiated from outside the device, so there are problems in that the structure is very large and expensive.

Therefore, the technical object of the present invention is to make it possible to always obtain tomographic images of a subject in the same state using a simple configuration.

[Means for solving problems]

This invention has been made with the above-mentioned points in mind, and includes a static magnetic field generating means for forming a static magnetic field, and a gradient magnetic field applied to an object to be measured placed in the static magnetic field by the static magnetic field generating means. a gradient magnetic field generating means, a high frequency generating and detecting means for applying a high frequency magnetic field to the object to be measured and detecting a nuclear magnetic resonance signal from the object to be measured, and controlling the gradient direction of the gradient magnetic field and the frequency of the high frequency magnetic field. In a nuclear magnetic resonance tomography apparatus comprising a control means and an image processing means for processing the nuclear magnetic resonance signal and creating a tomographic image of the object to be measured based on the signal, projecting light onto the object to be measured. When the light-emitting end of the optical fiber and the light-receiving end of the light-receiving fiber are installed almost facing each other, and the light-emitting direction and the light-receiving direction of both fibers, which fluctuate in conjunction with the periodic motion of the object to be measured, match. A light detection means for detecting light from the light-receiving optical fiber and outputting a detection signal is provided, and a driving means is provided for driving the gradient magnetic field generation means and the high frequency generation and detection means using the detection signal as a trigger. This is a nuclear magnetic resonance tomography apparatus characterized by the following.

[Effect]

1. Therefore, according to the present invention, the light-emitting end of the light-emitting fiber and the light-receiving end of the light-receiving optical fiber are attached to the object to be measured so that they are almost facing each other, so that periodic movements such as respiration of the object can be avoided. The light emitting direction of the light emitting optical fiber and the light receiving direction of the light receiving optical fiber are changed in conjunction with each other, and when the light emitting direction and the light receiving direction match, the light from the light receiving optical fiber is detected by the light detection means. A detection signal is outputted, and the driving means drives the gradient magnetic field generation means and the high frequency generation and detection means using the detection signal as an I-IJ signal, and the nuclear magnetic resonance signal from the object to be measured is detected and the detection signal is output from the object to be measured. tomographic images are obtained.

At this time, both 77' fibers are attached to the object to be measured, and the movement of the object to be measured and fluctuations in the light emitting and receiving directions of both fibers are always synchronized, so that the movement of the object to be measured is accurate. A tomographic image of the object under measurement is always obtained in the same state.

〔Example〕

Next, the present invention will be described in detail with reference to drawings showing one embodiment thereof.

In Fig. 1, (1) is a pair of static magnetic field generating means made of permanent magnets etc. that form a static magnetic field, and (2) is a static magnetic field generating means provided inside the static magnetic field generating means (1) and generated by the static magnetic field generating means +l]. A pair of gradient magnetic field coils (3) are provided inside the gradient magnetic field coil (2) as a gradient magnetic field generating means for applying a gradient magnetic field to a human body as a measured object, which will be described later, placed in a static magnetic field. A saddle-shaped high-frequency coil serves as a high-frequency generation and detection means. A human body (4) as an object to be measured is accommodated inside the high-frequency coil (3), and a high-frequency magnetic field is applied to the human body (4). 4) Detect the empty NMR signal.

(5) is a gradient magnetic field power supply for the gradient magnetic field coil (2), (6
) is a high frequency coil (3) Woko is a transmitter that transmits high frequency waves,
(7) is a receiver that receives the NMR signal from the high frequency coil (3), and (8) is the NMR signal transmitted through the receiver (7).
An A/D converter that converts signals from analog to digital (hereinafter referred to as A/D conversion), (9) is the A/D converted N]
VIi Human body based on R signal processed and the signal (4)
(10) is a CRT that displays the tomographic image of the human body (4) created by the processing means (9); (u) is a light projector; (12) is a light projector (11);
) is an optical fiber for transmitting light, and (13) is an optical fiber for receiving light. As shown in Fig. 2, a stretchable belt (
14), two supports (15a), (
15b) each supports a light emitting end of a light emitting fiber (12) and a light receiving end of a light receiving optical fiber (13);
The human body (
4).

(16) is when the light emitting direction of the light emitting optical fiber (12) and the light receiving direction of the light receiving optical fiber (13), which fluctuate in conjunction with the periodic breathing movement of the human body (4), match. (17) is a driving means which detects light from a light-receiving optical fiber (13) and outputs a detection signal which is an electric signal. 5) and a transmitter (6) to apply a gradient magnetic field by a gradient magnetic field coil (2) and a high-frequency magnetic field by a high-frequency coil (3) to a human body (4).

Although not shown in FIG. 1, the gradient direction of the gradient magnetic field by the gradient magnetic field coil (2) and the high-frequency coil (
3) is provided to control the frequency of the high-frequency magnetic field, and after driving the transmitter (6), the receiver (7) is
) for driving the control means, the switching means and the image processing means (9).

The driving means (17) is constituted by a computer.

Now, when the chest or abdomen expands and contracts due to the breathing movement of the human body (4), as shown in Figures 3 (a) to (C), the direction of the belt (14) wrapped around the chest or abdomen and the light receiving light are The receiving direction of the fiber (light) changes.

As shown in FIG. 3(a), when expiration ends and the chest or abdomen contracts, both the light emitting direction and the light receiving direction are directed downward and do not match, and conversely, as shown in FIG. As shown in Figure C), when the chest or abdomen expands after inhalation, both the light emitting direction and the light receiving direction are directed upwards and do not coincide with each other.
As shown in 1)), in a certain state during inspiration or expiration, the light emitting direction and the light receiving direction match, and the light from the light emitting end of the light emitting optical fiber (12) is transferred to the light receiving optical fiber. (13) enters the light receiving end of the light detecting means (16)
The light from the light-receiving optical fiber (13) is detected and a detection signal is output, and the detection signal acts as a trigger to apply a gradient magnetic field and a high-frequency magnetic field to the human body (4) in the static magnetic field, and the high-frequency coil ( 3) causes N from the human body (4)
'MR signal is detected, and a tomographic image of the human body (4) is created and displayed on the CRT (Do).

At this time, the light projection direction is as shown in FIG. 3(b).

When the light reception directions match, the bulging state of the chest or abdomen of the human body (4) is always the same, and a tomographic image of the human body (4) in the same state can always be obtained.

In addition, the light emitting direction of the light emitting optical fiber (12) and the light receiving direction of the light receiving optical fiber (13) may be attached so as to be parallel to the height direction of the human body (4).

〔Effect of the invention〕

As described above, according to the nuclear magnetic resonance tomography apparatus of the present invention, the light-emitting end of the light-emitting optical fiber (12) and the light-receiving end of the light-receiving optical fiber (13) are substantially opposed to each other as the object to be measured. The light emitting direction of the light emitting optical fiber (I2) attached to the human body (4) and the light receiving direction of the light receiving optical fiber (13) fluctuate in conjunction with the periodic breathing movement of the human body (4). When the light detection means (+6) matches, the light from the light receiving optical fiber (field) is detected by the light detection means (+6).
) is used as a trigger to apply a gradient magnetic field and a high-frequency magnetic field to the human body (4).
It becomes possible to accurately detect the respiratory movement of the human body (4), and it is possible to always obtain a tomographic image of the human body (4) in the same state, and it is possible to reliably prevent blurring and artifacts in the tomographic image.

Further, since the optical fibers (+2) and (13+) are used, it is possible to prevent electrical noise from entering the measurement area, and to ensure safety for the human body (4).

[Brief explanation of drawings]

The drawings show one embodiment of the nuclear magnetic resonance tomography apparatus of the present invention, FIG. 1 is a block diagram, and FIG. 2(a). (b) is a front view and a plan view with both optical fibers attached, Figures 3 (a) to (C) are operation explanatory diagrams, and right side views of a part of Figure 2 in different states. be. (1) Static magnetic field generating means, (2) Gradient magnetic field coil, (
3) High frequency coil, (4) Human body, (11) Image processing means, (12) Optical fiber for light projection, (13)
Optical fiber for light reception, (16) ... light detection means, (17
)・Drive means.

Claims (1)

[Claims] (1) A static magnetic field generating means for forming a static magnetic field, a gradient magnetic field generating means for applying a gradient magnetic field to an object to be measured placed in the static magnetic field by the static magnetic field generating means, and a gradient magnetic field generating means for applying a high frequency magnetic field to the object to be measured. a high frequency generation and detection means for detecting a nuclear magnetic resonance signal from the object to be measured; a control means for controlling the gradient direction of the gradient magnetic field and the frequency of the high frequency magnetic field; In a nuclear magnetic resonance tomography apparatus comprising an image processing means for creating a tomographic image of the object to be measured based on a signal, the object to be measured is provided with a light emitting end of a light emitting optical fiber and a light receiving end of a light receiving optical fiber. and detect the light from the light receiving optical fiber when the light emitting direction and light receiving direction of both fibers, which fluctuate in conjunction with the periodic motion of the object to be measured, coincide with each other. 1. A nuclear magnetic resonance tomography imaging apparatus comprising: a light detection means for outputting a detection signal; and a drive means for driving the gradient magnetic field generation means and the high frequency generation and detection means using the detection signal as a trigger.