JPS60242844A - Diagnostic method and apparatus by nuclear magnetic resonance - 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 application field] The present invention relates to a diagnostic method using nuclear magnetic resonance.

In particular, the present invention relates to a method for obtaining a projected image of an observed element within a subject in a nuclear particle W machine tomography apparatus.

[Conventional technology]

With conventional nuclear resonance computer tomography equipment, in order to determine the position of the tomographic plane of the subject, it is necessary to use other tomography equipment, such as an X-ray computer tomography equipment, or to judge based on the experience of the technician. This is common. That is, the position of the tomographic plane of the subject is determined by a method such as making an estimate based on the relative position from a reference site based on tomographic images obtained by other tomography apparatuses. but,
This method has the disadvantage that positioning cannot be performed accurately and that a desired tomographic plane cannot be accurately imaged unless it is combined with another tomographic imaging device.

There are also nuclear magnetic resonance diagnostic devices that can scan for positioning, but they use tomographic images on tomographic planes perpendicular to the desired tomographic plane (sagittal plane, coronal plane, etc.). However, images of areas not included in the vertical tomographic plane could not be obtained, and were insufficient for positioning.

Furthermore, there is a method in which nuclear spins of the observed element are excited over the entire object without selecting a tomographic plane, thereby obtaining a perspective image. However, this method has the disadvantage that it takes too much time because it is necessary to wait for each excited spin to recover.

[Problem that the invention seeks to solve]

An object of the present invention is to provide a method for obtaining fluoroscopic images using nuclear magnetic resonance at high speed.

[Means for solving problems]

The diagnostic method using nuclear magnetic resonance of the present invention applies a main magnetic field to a subject, a selective magnetic field that selects a tomographic plane of the subject, and a nuclear magnetic resonance to the nuclei of atoms constituting the tissue of this tomographic plane. A high-frequency pulse to be given and a gradient magnetic field for projecting the nuclear magnetic resonance signal of the above-mentioned atomic nuclei are applied, and the nuclear magnetic resonance signal projected by the application of each magnetic field is observed, and from this signal, the above-mentioned tomographic plane is determined. In a nuclear magnetic resonance diagnostic method that performs calculations to compose nuclear magnetic resonance responses into images, the strength of the gradient magnetic field for projection is set to be the same for different tomographic planes of the subject, and the above calculations are performed. The method is characterized in that a fluoroscopic image of a subject is constructed from signals obtained by observing a plurality of tomographic planes.

Further, the nuclear magnetic resonance diagnostic apparatus of the present invention includes a means for applying a main magnetic field to a subject, a means for applying a selective magnetic field for selecting a tomographic plane of the subject, and a structure for forming a tissue of this tomographic plane. means for applying a radio frequency pulse that imparts nuclear magnetic resonance to the nucleus of the atomic nucleus; means for applying a gradient magnetic field for projecting the nuclear magnetic resonance signal of the atomic nucleus; A nuclear magnetic resonance diagnostic apparatus comprising: means for observing a nuclear magnetic resonance signal; and means for performing calculations for composing an image of a nuclear magnetic resonance response for the tomographic plane from the output signal of the observing means; The means for applying a gradient magnetic field includes means for setting the strength of the gradient magnetic field to be the same for different tomographic planes of the subject, and the means for performing the above calculation calculates the intensity of the subject from the signals obtained by observing a plurality of tomographic planes. It is characterized in that it includes means for configuring a perspective image.

[Effect]

The nuclear magnetic resonance diagnostic method of the present invention is characterized by observing nuclear magnetic resonance signals of multiple tomographic planes under the same gradient magnetic field for projection, thereby obtaining a fluoroscopic image of the subject at high speed. shall be.

[Explanation of Examples]

FIG. 1 is a block diagram of a nuclear magnetic resonance computer tomography apparatus that implements the nuclear magnetic resonance diagnostic method of the present invention.

The magnet assembly 1 includes a static magnetic field coil 2 that applies a constant magnetic field to a subject, an excitation coil 3 that provides a high-frequency pulse to excite the spin of an atomic nucleus, and a selection IF field that selects a tomographic plane of the subject. It includes a gradient coil 4 that applies a gradient magnetic field for projecting magnetic resonance signals, and a detection coil 5 that detects signals due to nuclear magnetic resonance within the subject.

In FIG. 1, only some of these coils are shown.

The control calculator 11 is connected to a sequence storage circuit 12. The sequence storage circuit 12 is connected to a gradient magnetic field drive circuit 13. The gradient magnetic field drive circuit 13 is connected to the gradient coil 4 . The static magnetic field power supply 14 is connected to the static magnetic field coil 2 . High frequency oscillator 15 is connected to gate modulation circuit 16 and phase detection circuit 19. The gate modulation circuit 16 is connected to the high frequency power amplifier 17 and the phase detection circuit 19. High frequency power amplifier 17 is connected to excitation coil 3 . The detection coil 5 is connected to a preamplifier 18. Preamplifier 18
is connected to the phase detection circuit 19. Phase detection circuit 19 is connected to data storage device 20 . data storage device 20
is connected to the ink face circuit 21. The ink face circuit 21 is connected to the data processing 51 calculation 822. The data processing computer 22 is connected to a display device 23.

The control computer 11 controls the operation of the device of this embodiment. Also, sequence memory mouth! By rewriting the contents of 12, various operation sequences can be realized.

The sequence storage circuit 12 generates a timing signal for collecting observation data of nuclear magnetic resonance signals, and controls the operation of the gradient magnetic field drive circuit 13 and the gate modulation circuit 16. Thereby, the sequence storage circuit 12 controls the generation sequence of gradient magnetic fields and high-frequency pulses.

The gradient magnetic field drive circuit 13 is connected to each of the X-axis, y-axis, and Z-axis gradient coils 4, and applies a selection magnetic field and a gradient magnetic field to the subject.

The high-frequency oscillator 15, the gate modulation circuit 16, and the high-frequency power amplifier 17 apply high-frequency pulses to the subject inserted into the magnet assembly 1 in order to impart nuclear magnetic resonance to the atomic nuclei constituting the tissue of the subject. is configured to apply. High frequency oscillator 15 generates a high frequency signal. The gate modulation circuit 16 operates according to the sequence 1. The high frequency signal output from the high frequency oscillator 15 is modulated by the timing signal from the a circuit 12 to generate a high frequency pulse.

The high frequency power amplifier 17 amplifies the power of the high frequency signals output from the gate modulation circuit 16 and supplies the amplified signals to the excitation coil 3.

The preamplifier 1 and phase detection circuit 19 collect nuclear magnetic resonance signals. The preamplifier 18 amplifies the nuclear magnetic resonance signal detected by the detection coil 5. Phase detection circuit 19
refers to the output signal of the high frequency oscillation circuit 15 and performs phase detection on the output of the preamplifier 18.

The observation data obtained through this is stored in the take storage device 20.
is stored in

The interface circuit 21 sends observation data stored in the data storage device 20 to the data processing computer 22. The data processing computer 22 performs arithmetic processing on the observation data and displays the image on the display device 23 .

Here, for positioning to obtain the x-y tomographic plane,
A case of obtaining a perspective image in the X direction of the yz plane will be described.

FIG. 2 is a diagram showing a tomographic plane of the subject, and FIG. 3 is a side view thereof.

For each tomographic plane in two directions, a nuclear magnetic resonance signal is encoded using a gradient magnetic field that is constant only in the X direction.

The gradient magnetic field in the X direction is set to "0". By performing arithmetic processing such as Fourier transformation on the data thus obtained, a projection in the X direction can be obtained. Furthermore, observation is performed by changing the tomographic plane in two directions, and a perspective image in the X direction on the yz plane is obtained.

FIG. 4 is a time chart showing a pulse sequence in an embodiment of the method of the present invention. This example shows a one-view pulse sequence using the spin echo method.

Since the two-directional gradient magnetic field is used to specify the tomographic plane of the subject, it will be referred to as a selection magnetic field Gz. Spins are selectively excited by a selective magnetic field Gz and a high frequency pulse (90° pulse). Thereafter, a gradient magnetic field cy in the X direction is applied for a certain period of time, and a high frequency pulse (180' pulse) is further applied to invert the spin. Furthermore, the gradient magnetic field GV in the X direction is applied again, and the echo signal is observed. The tomographic plane is moved by changing the selection magnetic field Gz, and the same operation is repeated while applying the gradient magnetic field Gy of the same value. Thereby, a perspective image in the X direction is obtained.

Since spin relaxation takes 1 to 2 seconds in the case of water, it is desirable to take this effect into account and not observe adjacent fault planes sequentially.

According to the present invention, by exciting different positions in each view, there is no need to wait for spin recovery, and therefore a perspective image can be obtained at high speed. For example, it takes several tens of milliseconds to observe one view, and the fault plane is observed at 20C at intervals of 2II11.
Assuming that the observation is performed over I11, the observation will be completed in a few seconds, and by performing calculation processing in parallel, a perspective image can be obtained in less than 10 seconds. Compared to the time it takes several tens of seconds to several minutes just to obtain an image of one tomographic plane for location determination, the method of the present invention can obtain a fluoroscopic image at extremely high speed.

In the above description, a case has been described in which a perspective image is obtained in the X direction on the yz plane. However, this direction can be selected arbitrarily. That is, a magnetic field obtained singly or in combination in the x, y, and z directions can be used as the selection magnetic field,
A magnetic field in a direction perpendicular to this can be used as a gradient magnetic field.

Further, although the above explanation has been made regarding the pulse sequence of the spin echo method, the present invention can be practiced with other pulse sequences.

〔Effect of the invention〕

As explained above, by the method of photographing a fluoroscopic image using nuclear magnetic resonance of the present invention, a fluoroscopic image of a subject can be obtained at high speed.

This fluoroscopic image enables accurate determination of the position of the tomographic plane necessary for diagnosis, and also has the effect that by comparing the tomographic image and the fluoroscopic image, it is possible to estimate the position relative to the whole.

Furthermore, the fluoroscopic image contains not only the internal structure of the subject but also information such as various relaxations and spin densities, and has the excellent effect of being able to utilize this information for diagnosis.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a nuclear magnetic resonance computer tomography apparatus that implements the nuclear magnetic resonance diagnostic method of the present invention. FIG. 2 is a diagram showing a tomographic plane of the subject. FIG. 3 is a side view of the tomographic plane of the subject. FIG. 4 is a time chart showing a pulse sequence of an embodiment of the nuclear magnetic resonance diagnostic method of the present invention. DESCRIPTION OF SYMBOLS 1... Magnet assembly, 2... Static magnetic field coil, 3... Excitation coil, 4... Gradient coil, 5...
Detection coil, 11... Control computer, 12... Sequence record to circuit, 13... Gradient magnetic field drive circuit, 14.
...Static magnetic field power supply, 15...High frequency oscillator, 16...
Gate modulation circuit, 17...high frequency power amplifier, 18.
...Preamplifier, 19...Phase detection circuit, 20...
Data storage device, 21...interface circuit, 22
...Data processing computer, 23...Display device. Patent applicant representative, patent attorney Naotaka Ide 1

Claims (1)

[Claims] fi+ For a subject, a main magnetic field, a selection magnetic field that selects a tomographic plane of this subject, and a high-frequency pulse that causes nuclear magnetic resonance to the nuclei of atoms constituting the tissue of this tomographic plane. , apply a gradient magnetic field for projecting the nuclear magnetic resonance signal of the above-mentioned atomic nucleus, observe the nuclear magnetic resonance signal projected by applying each of these magnetic fields, and from this signal, calculate the nuclear magnetic resonance signal for the above-mentioned tomographic plane. In a diagnostic method using nuclear magnetic resonance that performs calculations to compose responses into images, the strength of the gradient magnetic field for projecting is set to be the same for different tomographic planes of the subject, and the calculations are as follows: A diagnostic method using nuclear magnetic resonance, characterized by constructing a fluoroscopic image of a subject from signals obtained by observing multiple tomographic planes. (2) means for applying a main magnetic field to the subject; means for applying a selective magnetic field for selecting a tomographic plane of the subject; and applying nuclear magnetic resonance to the nuclei of atoms constituting the tissue of this tomographic plane. means for applying a radio frequency pulse; means for applying a gradient magnetic field for projecting a nuclear magnetic resonance signal of the atomic nucleus; and means for observing a nuclear magnetic resonance signal projected by the means for applying the gradient magnetic field. In the nuclear magnetic resonance diagnostic apparatus, the means for applying a gradient magnetic field includes a means for performing calculations for composing an image of a response of nuclear magnetic resonance for the tomographic plane from an output signal of the observing means, and a means for applying a gradient magnetic field. The method includes means for setting the intensity to be the same for different tomographic planes of the subject, and the means for performing the above calculation includes means for constructing a fluoroscopic image of the subject from signals obtained by observing a plurality of tomographic planes. Diagnostic equipment using nuclear magnetic resonance.