JPH11239568A - Three-dimensional imaging device using magnetic resonance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten time required for the entire three-dimensional imaging. SOLUTION: An object is excited by using RF bursts 1-1 and 1-2 amplitude modulated by a sinc function, a gradient magnetic field Gr applied at the time of excitation is repeatedly applied as a read-out gradient magnetic field 2 while inverting ht the polarity of inclination and first and second phase encoding gradient magnetic fields 3 and 4 are applied matched with the application. Echo groups 6-1 and 6-2 are mensurated while imparting the position information of a three-dimensional direction within horizontal axis mitigation time relating to the excitation of one time and three-dimensional images are reconstituted based on the mensurated echo groups. Thus, waste time for waiting for the recovery of vertical magnetization is utilized for imaging and the time required for the entire three-dimensional imaging is shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an imaging method and apparatus using nuclear magnetic resonance, and more particularly to a high-speed radio-frequency magnetic field pulse (RF pulse) for excitation by using an RF burst composed of a plurality of sub-pulses. Related to shooting technology.

[0002]

2. Description of the Related Art Magnetic resonance imaging (imaging) apparatuses include:
A device that measures a tomographic image of a subject using nuclear magnetic resonance, applying a high-frequency magnetic field pulse and a gradient magnetic field to a subject placed in a static magnetic field to excite atomic nuclei in the subject, thereby generating nuclei. It detects an echo accompanying magnetic resonance, and reconstructs an image of a desired region of the subject based on the detected echo.

A high-frequency magnetic field pulse (RF pulse) used for excitation is formed by forming a high-frequency magnetic field having a frequency proportional to the static magnetic field strength into a pulse shape. It is known that an RF burst pulse composed of a plurality of sub-pulses discretely arranged on a time axis is used as the RF pulse.

Here, as shown in FIG. 11, a high frequency magnetic field burst pulse (hereinafter simply referred to as amplitude modulation R) in which the amplitude of a series of sub-pulses 11 of an RF burst is modulated by a sinc function 12 is shown.
It is called F burst. A method using (1) is known (Japanese Patent Application No. Hei 7-170015). When the RF burst 11 on the time axis, which is amplitude-modulated by such a sinc function, is subjected to Fourier transform, it becomes a square periodic wave 14 having a specific width on the frequency axis, as shown in FIG. Here, assuming that the interval between the sub-pulses 11 constituting the RF burst 1 on the time axis is u [seconds], the period of the square periodic wave on the frequency axis is 1 / u [Hz].
become. If the cycle of the sinc function is T [seconds], the width of the square periodic wave 14 on the frequency axis is 1 / T [Hz]. In the magnetic resonance imaging apparatus, the frequency band measured by the gradient magnetic field is allocated to the coordinates in the real space, so the waveform on the frequency axis represents the excitation profile of the nucleus in the real space as it is, that is, the absolute value of the transverse magnetization. Will be. In particular, amplitude modulated RF burst 1 with T = 2u
Is used as the excitation RF pulse, the excited region and the non-excited region alternately appear in the same volume. Therefore, as shown in FIG.
The carrier frequency of the amplitude-modulated RF burst 1-1 of 1 / (2
u) Amplitude modulated RF burst 1 shifted by [Hz]
When the Fourier transform of 2 is performed, the excited region and the non-excited region are just interchanged. Therefore, two such amplitude-modulated RF bursts 1-1, 1-
By applying 2 to the subject, it is possible to excite almost all the atomic nuclei in the photographing cross section of the subject to perform photographing.

A specific photographing sequence for photographing a subject using the two amplitude-modulated RF bursts 1-1 and 1-2 in FIG. 12 is described in Japanese Patent Application No. 8-74960. One example is shown in FIG. The horizontal axis in FIG. 13 represents time, and the vertical axis represents the intensity of an RF pulse, a gradient magnetic field, or the like. FIG.
The symbol attached to each axis of 3 indicates that RF is a high-frequency magnetic field pulse, G
r is a gradient magnetic field in the first axis direction (lead-out gradient magnetic field) among the gradient magnetic fields in the orthogonal three axis directions, Gp is a gradient magnetic field in the second axis direction (phase encoding gradient magnetic field), and Gs is a gradient in the third axis direction. A magnetic field (slice gradient magnetic field or second phase encoding gradient magnetic field) is an echo accompanying Echo nuclear magnetic resonance. As shown, a first amplitude modulated RF burst 1-1 composed of five sub-pulses and a gradient magnetic field in the same direction as the readout gradient magnetic field 2 are applied at the same time to excite the nuclei in the subject. . Then, a third high-frequency magnetic field pulse (1
(80-degree pulse) 31 and a slice gradient magnetic field 34 are applied to reverse the magnetic moment of the nucleus in a section (imaging section) having a specific width perpendicular to the direction of the slice gradient magnetic field Gs, and the magnetic moment is outside the section. Disperse the phase of the magnetic moment of the nucleus. Next, an echo group is generated by applying the readout gradient magnetic field 2. Then, the polarity (direction of the gradient) of the readout gradient magnetic field 2 is reversed,
By repeating this, a plurality of echo groups are generated, and the number of echoes necessary for image reconstruction is measured. At this time, the polarity of the phase encoding gradient magnetic field 33 is repeatedly inverted in synchronization with the repetition of the polarity inversion of the readout gradient magnetic field 2. Then, by performing a two-dimensional inverse Fourier transform on a series of detected echo groups 36-1, a two-dimensional image having spatial information in the readout direction and the phase encoding direction is obtained. Next, the first amplitude modulation Rf burst 1-1
A second amplitude modulation R composed of the same five sub-pulses and having a carrier frequency shifted by 1 / (2u) [Hz]
At the same time, the F burst 1-2 and the gradient magnetic field in the same direction as the readout gradient magnetic field 2 are applied at the same time to excite the nuclei in the subject, and the echo group 36-2 is similarly measured. After the echo groups 36-1 and 36-2 measured in this way are respectively subjected to two-dimensional inverse Fourier transform and then synthesized, an entire image is obtained.

In the above-mentioned conventional example, magnetic resonance imaging using two amplitude-modulated RF bursts in which the carrier frequency of an RF burst amplitude-modulated by a sinc function is shifted to each other has been described. Describes a magnetic resonance imaging method using three or more amplitude-modulated RF bursts in which the carrier frequencies of the RF bursts whose amplitudes are modulated by the sinc function are shifted to each other. That is, it discloses an imaging in which the width of a square periodic wave on the frequency axis when an RF burst amplitude-modulated by a sinc function is Fourier-transformed, that is, the excitation width is the width of one pixel in the readout gradient magnetic field direction. For example, four amplitude-modulated RFs in which carrier frequencies of RF bursts amplitude-modulated by a sinc function are different from each other.
When the burst is used as an RF pulse for excitation and the relationship between the interval u between the sub-pulses forming the RF burst and the period T of the sinc function that amplitude-modulates the RF burst is T = 4u, one pixel is generated by one amplitude-modulated RF burst. 1 of
4 regions can be excited. Therefore, a total of four image data can be obtained by sequentially irradiating and photographing four amplitude-modulated RF bursts whose carrier frequencies are sequentially shifted by 1 / (4u) [Hz]. Then, if they are subjected to two-dimensional Fourier transform and then synthesized, it is possible to improve the spatial resolution in the readout direction without increasing the gradient magnetic field strength. In addition, it is 4 from the first
In the irradiations up to the first time, the regions to be excited are different from each other, so that it is not necessary to wait for the recovery of the longitudinal magnetization during the imaging.

In FIG. 13, the photographing sequence for obtaining a two-dimensional image has been described. However, for obtaining a three-dimensional image, for example, the photographing sequence shown in FIG. 14 is used. That is, as shown in the figure, instead of the slice gradient magnetic field 34 in FIG. 13, the echo is measured by applying while changing the intensity of the second phase encoding gradient magnetic field (Gp2) 4 in multiple steps and measuring them. After the three-dimensional inverse Fourier transform, it is necessary to synthesize. 14, the same components as those in FIG. 13 are denoted by the same reference numerals, and description thereof will be omitted. FIG.
In No. 3, since a slice needs to be selected using a 180-degree pulse, a spin echo by a 180-degree pulse is also generated. However, in three-dimensional imaging, since slice selection is unnecessary, a readout gradient magnetic field is used. Only the field echo due to the polarity reversal of 2 is generated.

In this way, the readout gradient magnetic field 2
A group of echoes is generated each time the polarity is inverted, and the first amplitude modulation R
A plurality of echo groups 6-1-n for the F burst 1-1;
A plurality of echo groups 6-2-n are measured for the second amplitude modulation RF burst 1-2. Then, in order to obtain a three-dimensional image, the sequence shown in FIG. 14 is performed n times as many times as necessary while changing the applied amount of the second phase encoding gradient magnetic field 4. That is, the echo group is measured by changing the number of pixels n in the direction of the second phase encoding gradient magnetic field 4 of the three-dimensional image by the same number n. In FIG. 14, the echo group 6-1-n indicates an echo group measured at the time of applying the n-th second phase encoding gradient magnetic field. In addition, in the measurement of the echo group 6-1-n and the measurement of the echo group 6-2-n, the excitation regions are different from each other. It is not necessary and can be performed continuously.

[0009]

However, FIG.
In the measurement of the echo group 6-1-n and the echo group 6-1-
In the measurement of (n + 1), since the excitation region is the same, 2
There must be time between two measurements to wait for the recovery of longitudinal magnetization. Generally, in imaging with a magnetic resonance imaging apparatus, the measurement time of an echo is as short as several tens of milliseconds. However, in order to wait for the recovery of longitudinal magnetization, the excitation flip angle is 90
When it is close, the time is generally set to about 0.5 to 2 seconds. For this reason, the time required for the entire photographing becomes longer.

For example, FIG. 15 shows an imaging procedure in which the number of pixels in the application direction of the second phase encoding gradient magnetic field 4 is set to 16 and the repetition time is set to 0.5 second using the imaging sequence of FIG. Show. The time required for measuring the echo group 6-1-n can be reduced as the performance of the gradient magnetic field generator increases. Now, it is assumed that the performance of the gradient magnetic field generator is a maximum gradient magnetic field intensity of 30 mT / m and a slew rate of 100 T / m / sec. At this time, the rise time for outputting the maximum gradient magnetic field strength is 3
0 / 0.1 = 250 microseconds. It is also assumed that the visual field in the readout gradient magnetic field application direction is 19 cm, the number of pixels in the readout gradient magnetic field application direction is 64, and the number of pixels in the first phase encoding gradient magnetic field application direction is 64. . Assuming that the half Fourier image reconstruction method is applied to the first phase encoding gradient magnetic field application direction and the image reconstruction is performed by measuring a total of 40 echoes, the echo group 6-1-n measurement of FIG. The number of reversals of the read-out gradient magnetic field Gr required for (5) is 40/5 = 8. The magnetic resonance frequency of a hydrogen nucleus at 1 Tesla is
Since it is about 43 MHz, the sampling rate at the time of echo measurement is 1 / (43 * 103) /30/0.19=
0.00000407, which is about 4 microseconds.
Therefore, the time required to measure one echo is 4 * 3
2 = 128 microseconds. The time required to measure five echo groups corresponding to five sub-pulses is 128 * 7
= 896 microseconds. The time required for the measurement of the echo group 6-1-n including the rise time of the readout gradient magnetic field is (896 + 300) * 8 = 9568,
10 ms or less. Therefore, as is clear from FIG. 15, the total time required for echo measurement is 10 * 2.
If the repetition time Tr is set to 0.5 seconds despite the fact that it is shorter than * 16 = 320 milliseconds, the time required for the entire three-dimensional imaging is 500 * 15 + 10 * 2 = 7520.
It can be seen that it takes about 7.5 seconds.

As described above, in the conventional three-dimensional imaging method, a two-dimensional image is obtained by executing an imaging sequence for applying an amplitude modulation burst for excitation and measuring an echo group once to obtain a two-dimensional image. The three-dimensional photographing is performed by repeatedly executing in the direction. Therefore, every time the imaging sequence in the three-dimensional direction is executed, 0.5 times for waiting for the recovery of the longitudinal magnetization is obtained.
There is a problem that a dead time of about 2 to 2 seconds needs to be provided, and the time required for the entire photographing becomes longer.

An object of the present invention is to provide a method and an apparatus for shortening the time required for three-dimensional imaging as a whole.

[0013]

In order to solve the above-mentioned problems, a three-dimensional imaging method according to the present invention comprises a plurality of high-frequency magnetic field sub-pulses arranged discretely on a time axis on a subject placed in a static magnetic field. A high frequency magnetic field burst pulse for excitation, which is amplitude-modulated by a sinc function, is applied together with a gradient magnetic field in the first axis direction among the three orthogonal axes, and the gradient magnetic field in the first axis direction is used as a readout gradient magnetic field. The gradient magnetic field is repeatedly applied while reversing the gradient, and in synchronization with the repetitive application, the gradient magnetic field in the second axis direction among the three orthogonal axes is used as the first phase encoding gradient magnetic field while reversing the gradient of the gradient magnetic field. In reconstructing an image by detecting a plurality of echo groups by repeatedly applying while shifting the phase information in the axial direction, the transverse magnetization relaxation time of nuclear magnetization related to the application of the high-frequency magnetic field burst pulse By repeatedly applying the gradient magnetic field in the third axis direction among the three orthogonal axes as the second phase encoding gradient magnetic field while shifting the phase information in the axial direction, the excitation is performed once by the high frequency magnetic field burst pulse. That is, a plurality of echo groups necessary for reconstructing a three-dimensional image are measured.

That is, the two-dimensional image information obtained by adding the spatial information in the first and second axial directions is converted into the first two-dimensional image information within the relaxation time of the horizontal axis of the nuclear magnetization (generally, about 0.15 to 0.2 seconds). It is characterized in that three-dimensional image information is obtained by adding spatial information in three-axis directions while changing it. Thereby, 1 by the high frequency magnetic field burst pulse (amplitude modulation RF burst)
Since three-dimensional image information can be obtained by one excitation, the number of repetitions of excitation by the amplitude modulation RF burst can be greatly reduced, and the entire imaging time of three-dimensional imaging can be reduced.

In this case, the discrete interval of the high frequency magnetic field sub-pulse is u, the period of the sinc function is T, and m =
When T / u is set (where m is an integer), the carrier frequency of the amplitude modulation RF burst is shifted by 1 / (mu) every time, and the measurement is repeated m times, and the obtained m images are combined to obtain the resolution. Can be improved. For example, m = 2
In the case of (1), the width of the square periodic wave on the frequency axis of the amplitude modulation RF burst is ｕu. Therefore, only one half of the volume of the object is excited by one excitation, and the resolution is reduced. However, when the carrier frequency is subsequently shifted by ｕ u, the remaining 領域 area is excited, so that the entire imaging area can be imaged, so that the resolution is improved. Since the two excitations have different excitation regions, there is no need to wait for the recovery of the longitudinal magnetization, so that there is no problem of lengthening the imaging time.

As a specific example of the method of applying the first and second phase encoding gradient magnetic fields applied in accordance with the readout gradient magnetic field, first, a square periodic wave on the frequency axis when Fourier-transforming an amplitude-modulated RF burst is described. Is the width of one pixel in the direction of the readout gradient magnetic field, and when the echo group measurement is performed, the readout gradient magnetic field and the first phase encoding gradient magnetic field are substantially synchronized to repeat the reversal of the polarity of the gradient. During the period when the polarity of the gradient of the magnetic field is reversed, the first
A blip group in which a blip-shaped gradient magnetic field is added to one of the phase-encoding gradient magnetic field and the second phase-encoding gradient magnetic field, and the polarity is arranged at regular intervals and is added in the direction of the same second phase-encoding gradient magnetic field. The polarity of the blip applied in the direction of the first phase encoding gradient magnetic field applied next to the odd-numbered blip and the polarity of the blip applied in the direction of the first phase encoding gradient magnetic field applied next to the even-numbered blip are opposite to each other. Can be given.

[0017]

Embodiments of the present invention will be described below. (First Embodiment) FIG. 1 shows an imaging sequence of an embodiment of a three-dimensional imaging method according to the present invention, and FIG. 2 shows a schematic configuration diagram of a magnetic resonance imaging apparatus to which the method is applied. . As shown in FIG. 2, the magnetic resonance imaging apparatus includes a magnet 101 for generating a static magnetic field, a coil 102 for generating a gradient magnetic field, a sequencer 104, a gradient magnetic field power supply 105, an RF pulse generator 106, and a probe 107.
And so on. The sequencer 104 sends a command to the gradient magnetic field power supply 105 and the RF pulse generator 106 to generate a gradient magnetic field and an RF pulse from the coil 102 and the probe 107, respectively. Usually, the RF pulse is
The output of the RF pulse generator 106 is output to the RF power amplifier 11
5 through the probe 107 and the subject 103
Is applied to The signal generated from the subject 103 is received by the probe 107 and detected by the receiver 108. The magnetic resonance frequency used as the reference for detection is the sequencer 1
04 is set. The detected signal is calculated by the computer 10
9, where signal processing such as image reconstruction is performed. The result is displayed on the display 110. If necessary, signals and measurement conditions can be stored in the storage medium 111. The subject 103 is set in a magnetic field formed by the magnet 101 and the coil 102.

When it is necessary to adjust the uniformity of the static magnetic field, a shim coil 112 is used. The shim coil 112 includes a plurality of channels, and a current is supplied from a shim power supply 113. When adjusting the uniformity of the static magnetic field, the current flowing through each coil is controlled by the sequencer 104. Sequencer 1
04 sends a command to the shim power supply 113 to generate an additional magnetic field from the coil 112 to correct the non-uniformity of the static magnetic field. The sequencer 104 normally controls each device to operate at a timing and intensity programmed in advance. Among these programs, the one that particularly describes the RF pulse, the gradient magnetic field, and the timing and intensity of the echo reception is called an imaging sequence.

A three-dimensional photographing method according to an embodiment of the present invention will be described based on a photographing sequence shown in FIG.
In FIG. 1, in order from the top, a high-frequency magnetic field pulse RF, a readout gradient magnetic field Gr, and a first phase encoding gradient magnetic field Gp
1, second phase encoding gradient magnetic field Gp2, echo Ech
The respective time charts of “o” are shown. In the figure, the horizontal axis represents time, and the vertical axis represents the intensity of RF pulses, gradient magnetic fields, and the like.

As shown, the first RF burst 1-1
And the readout gradient magnetic field 2 are applied at substantially the same time to excite the subject. The first RF burst 1-1 is shown in FIG.
Are the same burst pulses as the amplitude modulated RF burst 1-1 shown in FIG. Thereafter, the echo group 6-1 is extracted as a field echo by repeating the polarity inversion of the gradient of the readout gradient magnetic field 2.

In order to perform three-dimensional imaging, it is necessary to provide position information in the direction of the first phase encoding gradient magnetic field (Gp1) 3 and the direction of the second phase encoding gradient magnetic field (Gp2) 4. Therefore, when measuring the echo group 6-1, the polarity of the gradient of the readout gradient magnetic field (Gr) 2 is reversed according to the period including the time when the applied amount of the readout gradient magnetic field (Gr) 2 is zero. In accordance with the timing, a blip-shaped gradient magnetic field is applied to only one of the first phase encoding gradient magnetic field 3 and the second phase encoding gradient magnetic field 4. The first phase encoding gradient magnetic field 3 is repeatedly applied in synchronization with the polarity reversal of the readout gradient magnetic field 2 and with the same polarity, and a blip-shaped gradient magnetic field (blip 3 ′) is applied thereto.
Is applied.

Here, of a plurality of (five in the example shown) blips 4-1 to 4-15 applied in the direction of the second phase encoding gradient magnetic field 4 having a positive polarity and arranged at a constant interval, A blip 3 'applied in the direction of the first phase encoding gradient magnetic field 3 applied next to the odd-numbered blip, and a blip applied in the direction of the first phase encoding gradient magnetic field 3 applied next to the even-numbered blip Blips in each direction are applied so that the polarities of 3 'are opposite to each other.

Here, the operation of the blip will be described with reference to FIG. First, the readout gradient 2 and the first
The echo group 6-1-1 of FIG. 1 is measured in the first 10 msec measurement in which the phase encoding gradient magnetic field 3 is repeatedly applied while reversing the polarity. Echo group 6-1-1 1 read corresponding to one rectangular wave of read-out gradient magnetic field 2
Considering the two echoes in the inverse Fourier transformed k-space,
As shown in FIG. 3, for example, position information corresponding to one scanning line 21 in the kx, ky space corresponding to the readout gradient magnetic field 2 and the first phase encoding gradient magnetic field 3 is included. Then, the position of the scanning line 12 is shifted in the ky direction by the blip 3 ′ of the first phase encoding gradient magnetic field 3. Therefore, the polarity of the readout gradient magnetic field 2 is inverted and applied repeatedly, and the blip 3 ′ of the first phase encoding gradient magnetic field 3 is applied, so that the position of the scanning line 12 on the k-space is changed in the ky direction. At the same time, the scanning direction is reversed and image information corresponding to one two-dimensional image is obtained. Then, the blips 4-1 to 4-1 of the second phase encoding gradient magnetic field 4
Each time 5 is applied, the position is shifted in the kz direction.
Thus, image information of a plurality of two-dimensional images superimposed in the kz direction, that is, three-dimensional image information is obtained. In the sequence of FIG. 1, since the number of blips of the second phase encoding gradient magnetic field 4 is 15, three-dimensional image information corresponding to 16 two-dimensional images is obtained. The number of two-dimensional images in the kz direction that can be taken is limited by the transverse magnetization relaxation time (for example, 150 to 200 msec) due to one excitation, and the measurement time to obtain one two-dimensional image is 10 msec. 10
It will be limited to ~ 20.

Next, the same RF burst 1-2 as shown in FIG. 12 is used as a second RF burst 1-2, and a gradient magnetic field Gr in the readout direction is applied almost simultaneously. By repeating the polarity reversal of 2, the echo group 6-2 is extracted as a field echo. At this time, as in the measurement of the echo group 6-1, during the period including the time when the applied amount of the readout gradient magnetic field is zero, either the first phase encoding gradient magnetic field or the second phase encoding gradient magnetic field is used. A blip-shaped gradient magnetic field is applied to only one of them.

In the photographing sequence shown in FIG. 1, the first half and the second half correspond to the first RF burst 1-1 and the second RF burst.
The carrier frequencies of bursts 1-2 are 互 い に u [H
z] The sequence is exactly the same except that it is shifted. Therefore, the waveform on the frequency axis when the first RF burst 1-1 is Fourier-transformed becomes the square periodic wave shown in FIG. 4, and half the volume of the imaging region is excited. Further, the waveform on the frequency axis when the second RF burst 1-2 is Fourier-transformed becomes a waveform obtained by shifting the square periodic wave shown in FIG. 4 by half a period, and the remaining half volume of the imaging region is excited. You. For example, as shown in FIG. 4, when the first RF burst 1-1 is applied to the subject, the width of the square periodic wave of the excitation profile is 3 mm, and the pixel size in the direction of the readout gradient magnetic field of the captured image is 6 mm. The conditions are set to be millimeters, and the obtained plurality of echo groups are subjected to two-dimensional inverse Fourier transform. The positional relationship between one pixel of the image obtained based on this and the excitation profile is as shown in FIG. By the way, if an amplitude-modulated RF burst composed of an infinite number of sub-pulses is used as an RF pulse for excitation, the excitation profile becomes a perfect square periodic wave. However, in the imaging sequence of FIG. 1, the excitation profile is not a perfect square periodic wave because an RF burst including five sub-pulses is used, but the excitation profile can be regarded as a substantially square periodic wave here. It will be described as an example.

One pixel of an image obtained by applying the first RF burst 1-1 to a subject and photographing has information of only a 3 mm area that is actually excited. Next, a second RF burst 1-2 in which the carrier frequency is shifted by 1 / (2u) [Hz] is applied to the subject to capture an image, and the echo group is subjected to two-dimensional inverse Fourier transform.
Not excited in the first RF burst 1-1 3
An image having information of only the millimeter area can be obtained. Therefore, as shown in FIG. 5, by alternately arranging and combining two images every other pixel, an image having a spatial resolution of 3 mm in the direction of the readout gradient magnetic field can be obtained. That is, the pixel size in the direction of the readout gradient magnetic field of the captured image can be improved from 6 mm to 3 mm. FIG. 5 schematically shows the synthesis method. An image 20-1 obtained by performing a two-dimensional Fourier transform on the echo group 6-1-1 and an echo group 6-2-1
The image 20-2 obtained by performing the two-dimensional Fourier transform on
A two-dimensional image 20 is obtained by alternately arranging every other pixel. The first RF burst 1-1 and the second RF burst 1-
In the application of 2, since the regions to be excited are different from each other, there is no need to wait for the recovery of the longitudinal magnetization between the two imagings. As described above, in the case of the first RF burst 1-1 and the second RF burst 1-2 using five sub-pulses, the excitation profile does not become a perfect square periodic wave, so Although some leakage occurs, it is of a level that causes no practical problem.

Further, the echo groups 6-1 and 6-2 are respectively subjected to three-dimensional inverse Fourier transform, and two three-dimensional images are alternately arranged at every other pixel (pixel) in the direction of the readout gradient magnetic field Gr. Combine. As a result, 3
A two-dimensional image is reconstructed. In the first half and the second half of the imaging sequence shown in FIG. 1, the excited regions are different from each other, so that it is not necessary to wait for the recovery of the longitudinal magnetization between the two measurements.

Here, if imaging is performed with the same number of pixels, visual field, and readout gradient magnetic field strength as in the conventional imaging sequence shown in FIGS. 14 and 15, the time required for the measurement of the echo group 6-1-1 is 10 times. Less than a millisecond. Therefore, 32 echo groups (6-1-1 to 6-1-16, 6-2-1 to 6-2-1)
The time required for the measurement 6) (the time required for the entire shooting) is RF
The time can be set to 320 milliseconds or less including the application time of the bursts 1-1 and 1-2. As a result, when performing three-dimensional imaging using the conventional imaging sequences of FIGS. 14 and 15, it took about 7.5 seconds as described above. However, according to the present embodiment, the entire three-dimensional imaging is performed. This has the effect of greatly reducing the time required.

As described above, in the three-dimensional imaging method of FIG. 1, first, a plurality of high-frequency magnetic field sub-pulses discretely arranged on the time axis are applied to a subject placed in a static magnetic field.
An RF burst for excitation, which is amplitude-modulated by a function, is applied together with a gradient magnetic field in a first axis direction among three orthogonal axes.
After that, the gradient magnetic field in the first axis direction is repeatedly applied while the gradient of the gradient magnetic field is reversed as a readout gradient magnetic field. Then, in synchronization with the repetitive application, the gradient magnetic field in the second axis direction among the three orthogonal axes is used as the first phase encoding gradient magnetic field, and the gradient information of the gradient magnetic field is inverted while the phase information in the axial direction is shifted. While applying repeatedly, a plurality of echo groups are detected to reconstruct an image. At that time, R
Within the transverse magnetization relaxation time of nuclear magnetization related to the application of the F burst,
By repeatedly applying a gradient magnetic field in the third axis direction among the three orthogonal axes as a second phase encoding gradient magnetic field while shifting phase information in the axial direction by blip, RF
A plurality of echo groups necessary for reconstructing a three-dimensional image are measured by one excitation of the burst.

In other words, the two-dimensional image information obtained by adding the spatial information in the first and second axial directions is converted into the time within the relaxation time of the horizontal axis of the nuclear magnetization (usually, about 0.15 to 0.2 seconds). By giving while changing the spatial information in the third axis direction,
Since the three-dimensional image information is obtained, the number of repetitions of the excitation by the RF burst can be greatly reduced, and the entire imaging time of the three-dimensional imaging can be greatly reduced.

As described above, if the time for capturing a three-dimensional image can be reduced, a moving image can be displayed. FIG. 6A shows an example of the moving image display procedure. The echo groups 6-1 and 6-2 are measured by the imaging sequence of FIG. 1, and each is subjected to three-dimensional inverse Fourier transform to obtain two three-dimensional images. Two three
The two-dimensional images are alternately arranged in the direction of the readout gradient magnetic field at every other pixel and synthesized. Further, moving images are realized by successively photographing the same photographing region and sequentially displaying the three-dimensional images on a display. In the case of this moving image display, since the same imaging region is continuously imaged, the repetition time Tr is set to 0.5 seconds for the purpose of waiting for the recovery of the longitudinal magnetization. Therefore, in the moving image display procedure shown in FIG. 6A, the image is updated and displayed on the display once every 0.5 seconds, so that a moving image with good motion can be displayed. For example, it can be used for observing the brain activation state over time, such as brain function measurement using a magnetic resonance imaging (MRI) device. By performing brain function measurement using such a three-dimensional image, it is possible to extract more detailed brain function information than when performing brain function measurement using a two-dimensional image.

That is, when the conventional three-dimensional imaging sequence shown in FIGS. 14 and 15 is used, since the time required for the entire three-dimensional imaging takes 7.5 seconds or more, at least once every 7.5 seconds. The image is updated only at a certain rate. In this regard, FIG.
By using the imaging sequence described above, the time resolution of brain function measurement can be improved, and more detailed brain function information can be extracted. Also, in the three-dimensional function measurement other than the brain function, since the time change of the substance is three-dimensionally observed, the higher the time resolution, the more detailed function information can be extracted. The echo groups 6-1 and 6-1
6-2 can perform the three-dimensional inverse Fourier transform independently, so that the moving image display procedure may be the procedure shown in FIG. 6B. That is, the echo group 6-1 is measured, and a three-dimensional image obtained by performing a three-dimensional inverse Fourier transform on the echo group 6-1 is displayed with a gap of one pixel per pixel in the direction of the readout gradient magnetic field. Next, the echo group 6-2 is measured, and a three-dimensional image obtained by performing a three-dimensional inverse Fourier transform on the echo group 6-2 is displayed at the position of the gap at every pixel in the direction of the readout gradient magnetic field. According to the moving image display procedure shown in FIG. 6B, the image is updated every other pixel in the direction of the readout gradient magnetic field once every 0.25 seconds.
Can be displayed on the display.

By the way, the photographing sequence of FIG.
Although an example using a 2u RF burst has been described, the present invention is not limited to this. In short, m = T / u
(Where m is preferably an integer), the carrier frequency of the RF burst is shifted by 1 / (mu) each time, the measurement is repeated m times, and the obtained m images are combined to obtain a two-dimensional image. You can do so. For example, for an RF burst amplitude-modulated with a sinc function having the excitation profile shown in FIG.
FIG. 7 shows the positional relationship between the excitation profile and one pixel in the case of the RF burst in which the period T of the function is doubled. That is, when the pixel size is 6 mm,
Image data of an area of 1.5 mm can be measured by capturing one RF burst. After obtaining the first image data, the carrier frequency of the RF burst is set to 1 / (4u) [Hz].
If a total of four pieces of image data are acquired while shifting, and then combined after two-dimensional Fourier transform, it is possible to improve the spatial resolution in the readout direction without increasing the gradient magnetic field strength. In the first to fourth irradiations, the regions to be excited are different from each other, so that it is not necessary to wait for the recovery of the longitudinal magnetization during the imaging.

(Second Embodiment) FIG. 8 shows a main part of a three-dimensional imaging sequence according to another embodiment of the present invention.
This embodiment is different from the embodiment of FIG. 1 in that the procedure for giving the position information is changed. That is, another example of a timing pattern for applying a blip-shaped gradient magnetic field to the first and second phase encoding gradient magnetic fields is shown. As shown, in FIG. 8, the readout gradient G
r, the method of applying the first phase-encoding gradient magnetic field Gp1 and the second phase-encoding gradient magnetic field Gp2 (the portion corresponding to the readout) is shown, and the RF bursts 1-1, 1-2 and the excitation The application of the gradient magnetic field is omitted.

In this embodiment, as in the case of FIG.
The first phase encoding gradient magnetic field 3 has the same polarity and inverted polarity almost in synchronization with the readout gradient magnetic field 2.
In addition, only one of the first phase encoding gradient magnetic field 3 and the second phase encoding gradient magnetic field 4 is included in a period including a time when the application amount of the readout gradient magnetic field is zero, that is, in accordance with the polarity inversion timing. , A blip-shaped gradient magnetic field is applied. In the group of blips applied in the direction of the second phase encoding gradient magnetic field 4 having the same polarity arranged at regular intervals, the application is performed in the direction of the first phase encoding gradient magnetic field 3 applied next to the odd-numbered blip. The blip in each direction is applied so that the polarity of the blip to be applied and the polarity of the blip applied in the direction of the first phase encoding gradient magnetic field 3 applied next to the even-numbered blip are opposite to each other.

For example, the second phase encoding gradient magnetic field 4
Of the blip group applied in the direction of blip 4-1-1
4-1-15 are positive polarity blip groups arranged at regular intervals. Then, among the blips 4-1-1 to 4-1-1-15, the odd-numbered blips 4-1-1, 4-1-1, and 4-1-1-
5,4-1-7,4-1-9,4-1-11,4-1-13,4
Blip 3-2, 3-4, 3-6, applied in the direction of the first phase encoding gradient magnetic field 3 applied next to -1-15
The polarities of 3-8, 3-10, 3-12, 3-14, and 3-16 are negative. Also, even-numbered blips 4-1-2, 4-1-1-
4,4-1-6,4-1-8,4-1-10,4-1-12,4
Blips 3-3, 3-5, 3-7, applied in the direction of the first phase encoding gradient magnetic field 3, which is applied subsequent to -1-14.
The polarity of 3-9, 3-11, 3-13, 3-15 is positive.
Also, among the blip groups applied in the direction of the second phase encoding gradient magnetic field 4, the blips 4-2-1 to 4-2-2,.
.. Are blips having negative polarity arranged at regular intervals. Of the blips 4-2-1 to 4-2-2,..., The first phase encoding gradient magnetic field 3 applied next to the odd-numbered blips 4-2-1, 4-2-2,. Are negative in the direction of the first phase encode gradient magnetic field 3 applied next to the even-numbered blips 4-2-2,. Blip applied 3-2
The polarity of 0 is positive. The three-dimensional image photographed by such a photographing sequence is the same as that in the embodiment of FIG. 1, and the time for three-dimensional photographing can be greatly reduced.

(Third Embodiment) FIG. 9 shows a main part of a three-dimensional imaging sequence according to still another embodiment of the present invention. The present embodiment is different from the embodiments of FIGS. 1 and 8 in that the procedure for giving position information is changed. That is, yet another example of a timing pattern for applying a blip-shaped gradient magnetic field to the first and second phase encoding gradient magnetic fields is shown. As shown, in FIG. 8, the readout gradient magnetic field Gr, the first phase encoding gradient magnetic field G
Only the method of applying p1 and the second phase encoding gradient magnetic field Gp2 (portion corresponding to the readout) is shown, and the application of the RF bursts 1-1 and 1-2 and the application of the excitation gradient magnetic field are omitted. .

In this embodiment, as in the case of FIG.
The first phase encoding gradient magnetic field 3 has the same polarity and inverted polarity almost in synchronization with the readout gradient magnetic field 2.
In addition, only one of the first phase encoding gradient magnetic field 3 and the second phase encoding gradient magnetic field 4 is included in a period including a time when the application amount of the readout gradient magnetic field is zero, that is, in accordance with the polarity inversion timing. , A blip-shaped gradient magnetic field is applied. In the group of blips applied in the direction of the second phase encoding gradient magnetic field 4 having the same polarity arranged at regular intervals, the application is performed in the direction of the first phase encoding gradient magnetic field 3 applied next to the odd-numbered blip. The blip in each direction is applied so that the polarity of the blip to be applied and the polarity of the blip applied in the direction of the first phase encoding gradient magnetic field 3 applied next to the even-numbered blip are opposite to each other. The three-dimensional image photographed by such a photographing sequence is the same as that in the embodiment of FIG. 1, and the time for three-dimensional photographing can be greatly reduced.

(Fourth Embodiment) FIG. 10 shows a main part of a three-dimensional imaging sequence according to still another embodiment of the present invention. This embodiment is different from the embodiments of FIGS. 1, 8 and 9 in that the method of giving position information is changed. That is, yet another example of a timing pattern for applying a blip-shaped gradient magnetic field to the first and second phase encoding gradient magnetic fields is shown. As shown in the drawing, the first phase encoding gradient magnetic field 3 is the same in that it is applied repeatedly inversion in synchronization with the repetition of inversion of the readout gradient magnetic field 2. However, the relationship between the blips applied to the first and second phase encoding gradient magnetic fields 3 and 4 is opposite to that shown in FIG.

That is, of the blip group applied in the direction of the first phase encoding gradient magnetic field 3 having the same polarity and arranged at a constant interval, the second phase encoding gradient magnetic field 4 applied next to the odd-numbered blip is used. The blip applied in each direction is applied such that the polarity of the blip applied in the direction and the polarity of the blip applied in the direction of the second phase encoding gradient magnetic field 4 applied next to the even-numbered blip are opposite.
In the figure, only the blips 3-1 and 3-2 are shown as the blips applied in the direction of the first phase encoding gradient magnetic field 3,
Illustrations after the blip 3-2 are omitted. The omitted part is
At the same interval as the blips 3-1 and 3-2,
There are 3-7. That is, among the blip groups applied in the first phase encode gradient magnetic field application direction, the blips 3-1 to 3-7 are blip groups having positive polarity arranged at regular intervals. Among the blips 3-1 to 3-7, the polarity of the blip 4-2-1 applied in the second phase encoding gradient magnetic field application direction applied next to the odd-numbered blip 3-1 is negative, The polarity of the blip 4-3-1 applied in the second phase encoding gradient magnetic field application direction applied after the even-numbered blip 3-2 is positive. The three-dimensional image photographed by this photographing sequence is the same as in the embodiment of FIG. 1, and the time for three-dimensional photographing can be greatly reduced.

Performing three-dimensional imaging by reading out while applying the first and second phase encodings within the transverse magnetization relaxation time, which is a feature of the present invention, can be performed in imaging sequences other than the above-described imaging sequences. The same applies. In other words, a plurality of RF bursts having different carrier frequencies amplitude-modulated by a sinc function are used as excitation RF pulses,
The width of the square periodic wave on the frequency axis when the F burst is Fourier-transformed, that is, the excitation width is set to the width of one pixel in the direction of the readout gradient magnetic field. At the time of echo measurement, the readout gradient magnetic field and the first phase encode gradient are used. During a period including a period in which the magnetic field is almost synchronized and the polarity is reversed, and the application amount of the readout gradient magnetic field is zero, the blip is performed on only one of the first phase encoding gradient magnetic field and the second phase encoding gradient magnetic field. To apply a gradient magnetic field like
A blip applied in the direction of the first phase encoding gradient magnetic field applied next to the odd-numbered blip among the blip groups applied in the direction of the second phase encoding gradient magnetic field having the same polarity arranged at a fixed interval; By applying the blips in the respective directions with the polarities of the blips applied in the first phase encoding gradient magnetic field application direction applied after the even-numbered blips being opposite to each other, the time required for the entire imaging can be reduced. It is possible. For example, the echo generation method need not be a field echo generated by inversion of the readout gradient magnetic field, but may be a spin echo generated by a 180-degree pulse.

[0042]

As described above, according to the present invention,
It is possible to reduce the time required for the entire three-dimensional imaging. As a result, the time resolution of the three-dimensional moving image display can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a photographing sequence of an embodiment of a three-dimensional photographing method of the present invention.

FIG. 2 is a schematic configuration diagram of a magnetic resonance imaging apparatus to which the three-dimensional imaging method of the present invention is applied.

FIG. 3 is a diagram illustrating a method of adding phase information of three-dimensional image information according to the shooting sequence of FIG. 1;

FIG. 4 is a diagram showing an excitation state in one pixel according to the imaging sequence of FIG. 1;

FIG. 5 is a diagram illustrating a method of synthesizing two two-dimensional images respectively measured by two RF bursts having different carrier frequencies.

FIG. 6 is a diagram illustrating a procedure for repeatedly executing three-dimensional imaging according to the imaging sequence of FIG. 1;

FIG. 7 is a diagram illustrating an example of an excitation state in one pixel when a sub-pulse interval of an RF burst is set to １ ／ of a cycle of a sinc function.

FIG. 8 is a diagram showing an imaging sequence according to another embodiment of the three-dimensional imaging method of the present invention.

FIG. 9 is a diagram showing an imaging sequence according to still another embodiment of the three-dimensional imaging method of the present invention.

FIG. 10 is a diagram showing an imaging sequence according to still another embodiment of the three-dimensional imaging method of the present invention.

FIG. 11 is a diagram illustrating an RF burst amplitude-modulated by a sinc function.

FIG. 12 is a diagram illustrating an amplitude-modulated RF burst in which the carrier frequency is shifted by 1 / (2u) [Hz].

FIG. 13 is a diagram showing a conventional two-dimensional imaging sequence using an RF burst amplitude-modulated by a sinc function.

FIG. 14 is a diagram illustrating an example of a conventional three-dimensional imaging sequence.

15 is a diagram illustrating a procedure of three-dimensional imaging using the imaging sequence in FIG.

[Explanation of symbols]

 1-1, 1-2 RF burst 2 Readout gradient magnetic field 3 First phase encoding gradient magnetic field 3 'blip 4 Second phase encoding gradient magnetic field 4-1 to 15 blip 6-1, 6-2 Echo group 101 Static magnetic field Generated magnet 102 Coil for generating gradient magnetic field 103 Subject 104 Sequencer 105 Gradient magnetic field power supply 106 High frequency magnetic field generator 107 Probe 115 RF power amplifier 108 Receiver 109 Computer 110 Display 111 Storage medium 112 Shim coil 113 Shim power supply

[Procedure amendment]

[Submission date] February 19, 1999

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Name of invention

[Correction method] Change

[Correction contents]

Title of the Invention Three-dimensional imaging apparatus using magnetic resonance

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0001

[Correction method] Change

[Correction contents]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensional radiographing apparatus using nuclear magnetic resonance, and more particularly to a radio frequency magnetic field pulse (RF pulse) for excitation composed of a plurality of sub-pulses.
The present invention relates to a technique for performing high-speed imaging by using an F burst.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction contents]

[0012] The present invention aims a Turkey to shorten the time required for the entire shooting of three-dimensional imaging.

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction contents]

[0013]

According to the present invention, there is provided a magnetostatic device for generating a static magnetic field applied to a subject.
Field generating means, and inclination in three orthogonal axes applied to the subject.
A gradient magnetic field generating means for generating a gradient magnetic field;
High-frequency magnetic field generating means for generating an applied high-frequency magnetic field pulse
And a signal for detecting an echo signal generated from the subject.
Detecting means, and the magnetism detected by the signal detecting means
Calculating means for reconstructing an image based on a resonance signal;
Using magnetic resonance comprising control means for controlling each means.
Three-dimensional magnetic resonance imaging apparatus,
Generating means is intended to generate a high-frequency magnetic field burst pulse for excitation formed by amplitude modulating a plurality of radio frequency magnetic field sub-pulses which are arranged discretely on the time axis in the sinc function, before
The control means includes the high-frequency magnetic field generation means and the gradient magnetic field.
And a high-frequency magnetic field
The gradient pulse and the gradient magnetic field in the first axis direction among the three orthogonal axes are applied together, and the gradient magnetic field in the first axis direction is repeatedly applied as a readout gradient magnetic field while reversing the gradient of the gradient magnetic field. The gradient magnetic field in the second axis direction among the three orthogonal axes is repeatedly applied while inverting the gradient of the gradient magnetic field and shifting the phase information in the axial direction in synchronization with Said
An echo signal is generated, and within the transverse magnetization relaxation time of nuclear magnetization related to the application of the high frequency magnetic field burst pulse, the orthogonal 3
By repeatedly applying the gradient magnetic field in the third axial direction among the axes as the second phase encoding gradient magnetic field while shifting the phase information in the axial direction, a three-dimensional image can be formed by one excitation by the high frequency magnetic field burst pulse. The control for measuring a plurality of echo groups required for reconstruction is performed by the high-frequency burst.
It should be executed several times by shifting the pulse carrier frequency.
Characterized in that was.

[Procedure amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction contents]

That is, the two-dimensional image information obtained by adding the spatial information in the first and second axial directions is converted to the second image information within the transverse magnetization relaxation time of the nuclear magnetization (generally, about 0.15 to 0.2 seconds). It is characterized in that three-dimensional image information is obtained by adding spatial information in three-axis directions while changing it. Thereby, three-dimensional image information can be obtained by one excitation by a high-frequency magnetic field burst pulse (amplitude modulation RF burst), so that the number of repetitions of excitation by the amplitude modulation RF burst can be greatly reduced. It is possible to shorten the entire shooting time of the two-dimensional shooting.

[Procedure amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction contents]

[0017]

Embodiments of the present invention will be described below. (First Embodiment) FIG. 1 shows a three-dimensional photographing apparatus according to the present invention.
Shows the imaging sequence of an embodiment according to the location, shows a schematic block diagram showing a magnetic resonance imaging apparatus comprising applying the imaging sequence in FIG. As shown in FIG. 2, the magnetic resonance imaging apparatus includes a magnet 1 for generating a static magnetic field.
01, coil 102 for generating gradient magnetic field, sequencer 1
04, gradient magnetic field power supply 105, RF pulse generator 106,
It is configured to include the probe 107 and the like. The sequencer 104 includes a gradient magnetic field power supply 105 and the RF pulse generator 10.
6 to coil 102 and probe 1 respectively.
From 07, a gradient magnetic field and an RF pulse are generated. Usually R
The F pulse is obtained by amplifying the output of the RF pulse generator 106 by the RF power amplifier 115 and applying the F pulse to the subject 103 through the probe 107. The signal generated from the subject 103 is received by the probe 107 and detected by the receiver 108. The magnetic resonance frequency used as the reference for detection is
Set by the sequencer 104. The detected signal is sent to the computer 109, where signal processing such as image reconstruction is performed. The result is displayed on the display 110. If necessary, signals and measurement conditions can be stored in the storage medium 111. The subject 103 is set in a magnetic field formed by the magnet 101 and the coil 102.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiromichi Shimizu 1-1-1 Uchikanda, Chiyoda-ku, Tokyo Inside Hitachi Medical Corporation

Claims (6)

[Claims] 1. A plurality of high-frequency magnetic field sub-pulses discretely arranged on a time axis are applied to a subject placed in a static magnetic field.
After applying a high-frequency magnetic field burst pulse for excitation, which is amplitude-modulated by the nc function, together with a gradient magnetic field in the first axis direction among the three orthogonal axes, the gradient magnetic field in the first axis direction is used as a readout gradient magnetic field. The gradient magnetic field is repeatedly applied while reversing the gradient, and in synchronization with the repetitive application, the gradient of the gradient magnetic field is reversed as a first phase encoding gradient magnetic field in the second axis direction among the three orthogonal axes, Upon repetitively applying while shifting the phase information in the axial direction to detect a plurality of echo groups and reconstruct an image, within the transverse magnetization relaxation time of nuclear magnetization related to the application of the high-frequency magnetic field burst pulse, The high frequency magnetic field burst pulse is obtained by repeatedly applying a gradient magnetic field in a third axis direction among the three orthogonal axes as a second phase encoding gradient magnetic field while shifting the phase information in the axial direction. 3D imaging method using magnetic resonance to measure a plurality of echo group necessary by one excitation to reconstruct the 3-dimensional image by. 2. The three-dimensional image capturing method according to claim 1, wherein the discrete interval of the high-frequency magnetic field sub-pulse is u,
When the period of the inc function is T and the value of T / u is m (where m is an integer), the carrier frequency of the high frequency magnetic field burst pulse is shifted by 1 / mu each time and the measurement is repeated m times. Three-dimensional image capturing method using magnetic resonance. 3. A high-frequency magnetic field burst pulse for excitation, which is obtained by amplitude-modulating a plurality of high-frequency magnetic field sub-pulses discretely arranged on a time axis by a sinc function, to a subject arranged in a static magnetic field space, is read out. Means for controlling an imaging sequence for measuring echoes associated with nuclear magnetic resonance occurring in the subject as a group of echoes by applying a readout gradient magnetic field, after applying the gradient magnetic field almost simultaneously with the directional gradient magnetic field; and A three-dimensional imaging apparatus using magnetic resonance, comprising: a calculation unit for creating a three-dimensional image of the subject based on a group, wherein a square periodic wave on a frequency axis when the high-frequency magnetic field burst pulse is Fourier-transformed The width is defined as the width of one pixel in the direction of the readout gradient magnetic field, and the readout gradient magnetic field and the first phase encoding gradient magnetic field are used during echo group measurement. The inversion of the polarity of the gradient is repeated in synchronism, and during the period in which the polarity of the gradient of the readout gradient magnetic field is reversed, a blip-shaped gradient magnetic field is applied to one of the first phase encoding gradient magnetic field and the second phase encoding gradient magnetic field. Of the blip groups which are arranged at regular intervals and have the same polarity in the direction of the second phase encoding gradient magnetic field, the blips which are added in the direction of the first phase encoding gradient magnetic field applied next to the odd-numbered blips. And a polarity of the blip added in the direction of the first phase encoding gradient magnetic field applied next to the even-numbered blips. 4. A high-frequency magnetic field burst pulse for excitation, which is obtained by amplitude-modulating a plurality of high-frequency magnetic field sub-pulses discretely arranged on a time axis by a sinc function, to a subject arranged in a static magnetic field space, is read out. Means for controlling an imaging sequence for measuring echoes associated with nuclear magnetic resonance occurring in the subject as a group of echoes by applying a readout gradient magnetic field, after applying the gradient magnetic field almost simultaneously with the directional gradient magnetic field; and A three-dimensional imaging apparatus using magnetic resonance, comprising: a calculation unit for creating a three-dimensional image of the subject based on a group, wherein a square periodic wave on a frequency axis when the high-frequency magnetic field burst pulse is Fourier-transformed The width is defined as the width of one pixel in the direction of the readout gradient magnetic field, and the readout gradient magnetic field and the first phase encoding gradient magnetic field are used during echo group measurement. The inversion of the polarity of the gradient is repeated in synchronism, and during the period in which the polarity of the gradient of the readout gradient magnetic field is reversed, a blip-shaped gradient magnetic field is applied to one of the first phase encoding gradient magnetic field and the second phase encoding gradient magnetic field. Are added in the direction of the second phase encoding gradient magnetic field applied next to the odd-numbered blip among the blip groups added in the direction of the first phase encoding gradient magnetic field having the same polarity and arranged at regular intervals. And a blip added in the direction of the second phase encoding gradient magnetic field applied next to the even-numbered blips, and the polarities of the blips added to each other are opposite to each other. 5. A high-frequency magnetic field pulse for excitation and a gradient magnetic field are applied to an object placed in a static magnetic field, and an echo generated from the object in response to the excitation is applied with a gradient magnetic field to obtain phase information and frequency. In a three-dimensional image capturing method of measuring while adding information and reconstructing a three-dimensional image based on the measured echo group and displaying the same on a display device, after applying a high-frequency magnetic field pulse for excitation and a gradient magnetic field, , 0.5 seconds to 2
A three-dimensional image capturing method using magnetic resonance, wherein a three-dimensional image of a subject is displayed within seconds. 6. A high-frequency magnetic field pulse for excitation and a gradient magnetic field are applied to a subject placed in a static magnetic field, and an echo generated from the subject in response to the excitation is applied with a gradient magnetic field to obtain phase information and frequency. In a three-dimensional image capturing method for measuring while adding information, reconstructing a three-dimensional image based on the measured echo group and displaying the three-dimensional image on a display device, 0.5 to 2 seconds
A three-dimensional image capturing method using magnetic resonance, characterized by displaying a three-dimensional moving image of a subject that changes within seconds.