JP3116362B2 - Inspection equipment using nuclear magnetic resonance - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an apparatus for measuring internal information of an object using nuclear magnetic resonance, and particularly to an apparatus for measuring the internal information of a substance such as lactic acid or amino acid in a living body. The present invention relates to an inspection apparatus using nuclear magnetic resonance, which can suppress a signal of a solvent having a large signal amount that hinders measurement of a signal of a minute compound.

[Conventional technology]

In a system in which a minute compound and a solvent coexist, the peak of the nuclear magnetic resonance signal of the minute compound molecule is hidden by the bottom of a large peak of the solvent molecule, and thus it is necessary to suppress the signal of the solvent molecule. Examples of this method include a method of using a difference in chemical shift to saturate nuclear magnetization of a solvent molecule,
Although there is a method of suppressing one quantum transition of the solvent molecule by selectively observing the signal of the multiquantum transition, the most widely used conventionally is the method after excitation of the solvent molecule and the minute compound molecule. A method of exciting only the nuclear magnetization of microscopic compound molecules by applying a plurality of high-frequency pulses at an appropriate pulse interval such that the magnitude of the flip angle becomes the ratio of the binomial coefficient using the phase difference. It is. The method of saturating the nuclear magnetization of the solvent molecule by utilizing the difference in the chemical shift described above is described in "Measurement of RLVold et al."
Spin Relaxation in Complex Systems "(J. Chem. Phy
s., 48, pp3831 (1968) also describes a method of suppressing one quantum transition of a solvent molecule by selectively observing a signal of a multiquantum transition.
litple Quantum Filter for the Imaging of Homonucle
ar Spin-spin Coupled Nuclei "(Proceedings of the
Fourth Annual Meeting of the society of Magnetic R
The descriptions in esonance in Medicine, London, pp145 (1985) are each helpful.

Further, utilizing the above-described phase difference after excitation between the solvent molecules and the minute compound molecules, a plurality of high-frequency pulses such that the magnitude of the flip angle becomes the ratio of the binomial coefficient are interposed at appropriate pulse intervals. In the method of exciting only the nuclear magnetization of minute compound molecules by applying the voltage, the pulse sequence can exist indefinitely according to the number of terms of the binomial coefficient.
l of Magnetic Resonance 55, pp283-300 (1983)), the flip angle ratio is 1: −3: 3: −1.
FIG. 2 shows a measurement method using a pulse sequence composed of high-frequency pulses such that

If the effect of the relaxation is neglected, the observation signal becomes maximum when the sum of the effective flip angles becomes π / 2. In this case, the flip angle of the first pulse “1” in the above pulse sequence is obtained. Becomes π / 16. When using the above measurement method under these conditions,
FIG. 3 (a) shows the locus of the nuclear magnetization vector of the solvent molecule in the rotating coordinate system based on the rotation frequency of the high-frequency pulse.
FIG. 3 (b) shows the locus of nuclear magnetization of the microscopic compound whose effective flip angle sum is π / 2. Here, the direction of the static magnetic field is defined as the Z direction, and the direction of applying the high frequency pulse is defined as the X direction. The rotation frequency of the high-frequency pulse is assumed to be equal to the resonance frequency of the solvent molecule.

In FIG. 2, immediately after the application of the pulse “1”, the nuclear magnetization of the solvent molecule and the nuclear compound are both in the YZ plane, and the angle between the Z axis and the nuclear magnetization is π / 16. The pulse '1' and the pulse '-3' are separated by a pulse interval time τ, during which a phase difference occurs between the solvent molecule and the nuclear magnetization of the microscopic compound according to the frequency difference of the precession. In the nuclear magnetization shown in FIG. 3B, this phase difference is π. Immediately after the pulse “−3” is applied, the nuclear magnetization of the solvent molecule receives a flip of −3π / 16, so that the angle between the Z axis and the nuclear magnetization of the solvent molecule is −2π / 16. On the other hand, the net flip received by the pulse '−3' of the nuclear magnetization of the microscopic compound molecule is 3π / 16, so that the angle between the Z axis and the nuclear magnetization of the microscopic compound molecule is −4π / 16. .

Next, when a pulse '3' is applied after a pulse interval time τ, the angle between Z3 and the nuclear magnetization of the solvent molecule becomes π / 16, and the angle between the Z axis and the nuclear magnetization of the microscopic compound molecule is formed. Is 7
π / 16. When the pulse '-1' is further applied after a pulse interval time τ, the angle between the Z axis and the nuclear magnetization of the solvent molecule finally becomes zero, and no solvent signal is observed. On the other hand, the angle between the Z axis and the nuclear magnetization of the microscopic compound molecule is 8
π / 16 = π / 2, and the observation signal becomes maximum. However, here, the influence of the non-uniformity of the static magnetic field is not considered.

This method has a relatively high suppression effect of the solvent signal, and when using a pulse sequence composed of an even number of high-frequency pulses,
There is an advantage that the effect of suppressing the solvent signal is not affected even when the inhomogeneity of the high-frequency magnetic field exists.

[Problems to be solved by the invention]

However, the prior art has a problem in that when the static magnetic field inhomogeneity is large, accurate phase operation becomes impossible, and the suppression effect of the solvent signal and the amount of observation signals are reduced.

The present invention has been made in view of the above circumstances, and an object thereof is to solve the above-described problems in the related art and to reduce the suppression effect of the solvent signal when there is inhomogeneity of the static magnetic field. An object of the present invention is to provide an inspection apparatus using nuclear magnetic resonance that suppresses a decrease in the amount of observation signals while suppressing the amount of observation signals.

[Means for solving the problem]

An object of the present invention is to provide an inspection apparatus using nuclear magnetic resonance that detects a nuclear magnetic resonance signal of an inspection object placed in a space to which a static magnetic field is applied. Applying a first pulse sequence consisting of an RF pulse having a flip angle ratio according to a binomial distribution to the object to be inspected, applying an inverted RF pulse to the object to be inspected, and having a constant pulse interval and a phase. Inverting sequentially, applying a second pulse sequence composed of RF pulses having a flip angle ratio according to a binomial distribution to the inspection target, and measuring each of the transverse magnetization signals generated from the inspection target, A first addition value that is a sum of absolute values of flip angles of each RF pulse of the first pulse sequence;
This is achieved by an inspection apparatus using nuclear magnetic resonance, wherein the sum of the absolute value of the flip angle of each RF pulse of the second pulse sequence and the second addition value is π / 2. You.

[Action]

Hereinafter, in the inspection apparatus using nuclear magnetic resonance according to the present invention, when a signal of a small compound is observed by a measurement method shown in FIG. 1 in a system in which a solvent molecule and a small compound molecule whose resonance frequencies are close to each other are mixed. Will be described. When the sum of the absolute values of the flip angles of the high-frequency pulses constituting the pulse sequence 1 and the pulse sequence 2 in the drawing is π / 2,
Observed signal is maximum. However, the effects of mitigation are ignored.
Also, the direction of application of the static magnetic field is set to the Z direction, and in a rotating coordinate system having the same rotation frequency as the high-frequency magnetic field, the pulse sequence 1,
The application direction of the pulse sequence 2 and the inversion pulse is defined as the X direction.

Assuming that the nuclear spin of the solvent molecule precesses at the same frequency as the high frequency pulse, the nuclear magnetization vector should return in the Z direction immediately after the application of the pulse sequence 1 if the static magnetic field is uniform. In the presence of uniformity, the frequency of the precession varies, so that the XY component remains as an error component. When an inversion pulse is applied in the X direction as shown in FIG. 1, this error component is inverted around the X axis, so that the pulse sequence 2
The error component caused by this is canceled. Accordingly, the error component due to the non-uniformity of the static magnetic field can be canceled as a whole.

On the other hand, since the micro compound molecules and the solvent molecules have different frequencies of precession, a phase difference occurs between the nuclear magnetizations of the pulse sequences 1 and 2 in both. For example, immediately before the application of the second high-frequency pulse of pulse sequence 1, the above-described phase difference is π.
The XY component of the nuclear magnetization vector M has only a -Y component immediately after the application of the pulse sequence 1 if the static magnetic field is uniform.
However, in the presence of the inhomogeneity of the static magnetic field, an X component occurs as an error component as shown in FIG. Immediately before the end of the pulse sequence 1 and immediately before the application of the inversion pulse, the phase of the nuclear magnetization vector M rotates π in the above-mentioned rotating coordinate system,
The signs of the X and Y components are reversed. Here, when an inversion pulse is applied in the X direction, the signs of the Y component and the Z component are reversed. The error component generated in the pulse sequence 2 is the pulse sequence 1
Is generated in such a direction as to cancel the error component generated in the step (1), the nuclear magnetization vector M returns almost in the Y direction immediately after the application of the pulse sequence 2.

〔Example〕

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

FIG. 4 is a block diagram showing an example of an inspection apparatus using nuclear magnetic resonance for obtaining a signal of a minute compound from a substance containing a large amount of solvent molecules. In the figure, 1 is a coil for generating a static magnetic field, 2 is a coil for generating a gradient magnetic field, and 3 is a test object. The test object is arranged in the coils 1 and 2. The sequencer 4 sends a command to the gradient magnetic field driver 5 and the high frequency oscillator 6 to apply a gradient magnetic field and a high frequency magnetic field. The high-frequency magnetic field is applied to the inspection target 3 by the high-frequency transmitter 9 via the high-frequency modulator 7 and the high-frequency amplifier 8.
A signal generated from the inspection target is received by the receiver 10, sent to the CP 14 through the amplifier 11, the phase detector 12, and the AD converter 13, where signal processing is performed. If necessary, signals and measurement conditions can be stored in the storage medium 15.

Now, a case where a ¹ H spectrum of a living body is measured will be described as an embodiment of the present invention. Lactic acid and amino acids contained in a trace amount in living organisms have many useful biochemical information, but cannot be measured without suppressing the signal of an overwhelmingly large amount of water molecules. For example, by ¹ H spectrum measurement of the biological in the magnetic field intensity 2.0 T (tesla), consider the case where the difference between the resonance frequency of water is to measure the signal of small compound serving as 80～300Hz.

First, the case where the measurement method shown in FIG. 1 is used will be described. The measurement method consists of two identical pulse sequences separated by a time τ and an inverted pulse. The pulse sequence has a flip angle ratio of 1: −, as shown in FIG.
It consists of high-frequency pulses such as 3: 3: -1. The above τ is equal to the pulse interval time τ separating adjacent high frequency pulses in the pulse sequence. If this pulse interval time τ is set to 2.6 msec, the difference in resonance frequency with water is about 1
The ratio of the apparent flip angles received by the pulse sequence to the nuclear magnetization at 90 Hz is 1: 3: 3: 1, and the maximum signal intensity is obtained. The flip angles α and α ′ of the high-frequency pulse “1” of the pulse sequence 1 and the pulse sequence 2 are, for example, α = α ′
= Π / 32, the net flip angle that the nuclear magnetization receives with two pulse sequences is ideally π / 2. The pulse width is set to be sufficiently short with respect to the pulse interval time π, for example, several tens msec.

By applying the pulse sequence 1, the net flip angle of the nuclear magnetization W of water is ideally zero, and should return to the static magnetic field application direction Z. Since it exists, the XY component remains as an error component. If an inversion pulse is applied after τ time after the application of the pulse sequence, an XY component is generated in the direction to cancel the error component by the applied pulse sequence 2 subsequently, so that the influence of the non-uniform static magnetic field is corrected as a whole. be able to.

On the other hand, the net flip angle of the nuclear magnetization M having a resonance frequency difference with water of about 190 Hz received by the pulse sequence 1 is π / 4.
Assuming that the application direction of the high-frequency pulse is X, it should ideally have only the YZ component. However, since the static magnetic field inhomogeneity actually exists, the X component becomes an error component as shown in FIG. Occurs. The nuclear magnetization M rotates about π around the Z axis during the time τ after the application of the pulse sequence, and an error component occurs during this time. This is shown in FIG. Next, when an inversion pulse is applied in the X direction, the nuclear magnetization M rotates π around the X axis as shown in FIG. Immediately after that, if the pulse sequence 2 is applied, a new error component is generated in a direction to cancel the error component generated by the pulse sequence 1, so that the nonuniformity of the static magnetic field is corrected as a whole as shown in FIG. be able to.

The NMR spectrum has a transverse relaxation time T ₂ , a line width Δω due to the inhomogeneity of the static magnetic field, and the like. Of these, the term due to the inhomogeneity of the static magnetic field will be described as δω.

When the static magnetic field inhomogeneity δω is 0.0 ppm, 0.1 ppm, 0.3 ppm, and 0.5 ppm, the transverse magnetization Mxy in the excitation plane obtained under the above-described conditions using the method shown in FIG. ) To (d)
Shown in The transverse magnetization Mxy is normalized by the initial value of the nuclear magnetization. The horizontal axis is a frequency offset based on the resonance frequency of water. Transverse magnetization Mx near frequency offset = 0
y is almost 0, and this area 9 is called a null area. When solvent suppression is performed using the method according to the present invention or the conventional method, the transverse magnetization curve has a rectangular shape, and nu
Ideally, the transverse magnetization Mxy = 0 in the ll region and the transverse magnetization Mxy = 1 in the excitation band.

On the other hand, when measuring using the conventional method shown in FIG. 2, the transverse magnetization Mx obtained under the same conditions as the method according to the present invention is used.
y is shown in FIGS. 6 (a) to 6 (d). However, in this case, the flip angle α = π / 16. The method according to the present invention shown in FIG. 1 is a measurement method in which the conventional method shown in FIG. 2 is divided into two times and an inversion pulse is interposed therebetween. This method is affected by static magnetic field inhomogeneity. Is to be reduced. The inverted pulse has the same phase as the other high-frequency pulses in FIG. 6 and 7, it can be seen that the method according to the present invention has the effect of reducing the maximum transverse magnetization due to the non-uniformity of the static magnetic field and the transverse magnetization in the null region.

Next, the conventional method shown in FIG. 8 is compared with the method according to the present invention shown in FIG. The measurement method shown in FIG. 8 uses a pulse sequence composed of three high-frequency pulses having a flip angle ratio of 1: −2: 1. The pulse interval is, for example, as shown in FIG.
Using the same values as in the figure, the frequency offset with water is 19
The frequency region around the resonance frequency of the nuclear magnetization M at 0 Hz is the excitation region. Assuming that the flip angle of the high-frequency pulse '1' is α = π / 8, the nuclear magnetization W of water is obtained by the above pulse sequence.
Is zero, the ideal flip angle returns to the static magnetic field application direction Z. On the other hand, since the flip angle applied to the nuclear magnetization M by the pulse sequence is π / 2, if the application direction of the high-frequency pulse is the X direction, ideally +
It falls down in the Y direction. However, in practice, since there is static magnetic field inhomogeneity, error components are generated for both W and M. In each case where the static magnetic field inhomogeneity is δω = 0.0 ppm, 0.1 ppm, 0.3 ppm, and 0.5 ppm, the transverse magnetization Mxy obtained by the above-described measurement method is calculated as the first
1 (a) to (d).

The measurement method according to the present invention shown in FIG. 9 is a measurement method composed of two identical pulse sequences separated by a time τ and an inverted pulse, and reduces the influence of this method due to the non-uniformity of the static magnetic field. Things. This pulse sequence is equal to the pulse sequence in FIG. However, in this case, the flip angle of the high-frequency pulse '1' is, for example, α = α '= π / 16
And the net flip angle that the nuclear magnetization M receives by the two pulse sequences is π / 2. The inverted pulse in this measurement method is out of phase by π / 2 with the inverted pulse in FIG. After application of the pulse sequence 1, the nuclear magnetization W of the water returns in the Z direction, but an XY component is generated as an error component due to the non-uniformity of the static magnetic field. If an inversion pulse is applied τ hours after the application of the pulse sequence, an XY component is generated in a direction to cancel the error component by the subsequently applied pulse sequence 2, so that the influence of the nonuniform static magnetic field as a whole is obtained. Can be corrected.

On the other hand, the net flip angle of the nuclear magnetization M having a resonance frequency difference with water of about 190 Hz received by the pulse sequence 1 is π / 4.
Assuming that the application direction of the high-frequency pulse is X, it should ideally have only the YZ component. However, since the static magnetic field inhomogeneity actually exists, the X component becomes an error component as shown in FIG. Occurs. The nuclear magnetization M rotates about π around the Z axis during the time τ after the application of the pulse sequence, and an error component occurs during this time. This is shown in FIG. Next, when an inversion pulse is applied in the Y direction, the nuclear magnetization M rotates π around the Y axis as shown in FIG. Immediately after this, if the pulse sequence 2 is applied, a new error component is generated in a direction to cancel the error component generated by the pulse sequence 1, so that the non-uniformity of the static magnetic field is corrected as a whole as shown in FIG. can do. Static magnetic field inhomogeneity is δω = 0.
FIG. 12 (a) shows the transverse magnetization Mxy obtained by the above-described measurement method for the nuclear cases of 0 ppm, 0.1 ppm, 0.3 ppm, and 0.5 ppm, respectively.
To (d).

11 and 12, it can be seen that the method of the present invention has the effect of reducing the maximum transverse magnetization due to the non-uniformity of the static magnetic field and increasing the transverse magnetization in the null region.

In the above embodiment, two specific pulse sequence giving methods have been described.However, the present invention is not limited to this. For example, it is possible to use various pulse sequence giving methods as described below. it can. That is, as described above, the signal is composed of a plurality of high-frequency pulses, the sum of the flip angles is zero for the signal from the solvent, and for the minute compound,
A pulse sequence that causes excitation is applied twice as first and second pulse sequences consecutively, and an inversion pulse is applied between the two pulse sequences to suppress the solvent signal. (1) When the first and second pulse sequences are the same pulse sequence and consist of an even number of high-frequency pulses, An inspection apparatus using nuclear magnetic resonance, wherein the phase difference between the inversion pulse and the pulse sequence is π / 2 (see FIG. 13).

(2) In the case where the first and second pulse sequences are the same pulse sequence and are composed of an odd number of high-frequency pulses, the inverted pulse and the pulse sequence have the same phase. Inspection device using (see Fig. 14).

(3) When the ratio of the absolute values of the high-frequency pulses included in the first and second pulse sequences is equal, the phases are opposite to each other, and both are composed of even-numbered high-frequency pulses, the inverted pulse and the pulse sequence are used. Are in phase with each other, an inspection apparatus using nuclear magnetic resonance (see FIG. 15).

(4) When the ratios of the absolute values of the high-frequency pulses included in the first and second pulse sequences are the same, and the phases are opposite to each other and both are composed of odd-numbered high-frequency pulses, the inversion pulse and the pulse sequence are used. An inspection apparatus using nuclear magnetic resonance, wherein the phase difference is π / 2 (see FIG. 16).

(5) The first pulse sequence is composed of an odd number of high-frequency pulses, and the second pulse sequence is composed of an even number of high-frequency pulses than the high-frequency pulses of the first pulse sequence.
When the first high-frequency pulse in one pulse sequence has the opposite phase, an appropriate waiting time is provided immediately before the application of the inversion pulse, and the inversion pulse and the first pulse sequence have the same phase. Inspection equipment using nuclear magnetic resonance
See Figure 17).

(6) The first pulse sequence is composed of odd-numbered high-frequency pulses, and the second pulse sequence is composed of even-numbered high-frequency pulses more than the high-frequency pulses of the first pulse sequence.
When the first high-frequency pulse in one pulse sequence has the same phase, an appropriate waiting time is provided immediately before the application of the inversion pulse, and the phase difference between the inversion pulse and the first pulse sequence becomes π / 2. An inspection apparatus using nuclear magnetic resonance (see FIG. 18).

(7) The first pulse sequence is composed of even-numbered high-frequency pulses, and the second pulse sequence is composed of a smaller number of odd-numbered high-frequency pulses than the high-frequency pulses of the first pulse sequence.
If the first high-frequency pulse in one pulse sequence has the opposite phase, an appropriate waiting time is provided immediately after the application of the inversion pulse, and the phase difference between the inversion pulse and the first pulse sequence becomes π / 2. An inspection apparatus using nuclear magnetic resonance (see FIG. 19).

(8) The first pulse sequence is composed of even-numbered high-frequency pulses, and the second pulse sequence is composed of a smaller number of odd-numbered high-frequency pulses than the high-frequency pulses of the first pulse sequence.
When the first high-frequency pulse in one pulse sequence has the same phase, an appropriate waiting time is provided immediately after the application of the inversion pulse, and the inversion pulse and the first pulse sequence have the same phase. Inspection equipment using nuclear magnetic resonance
See Figure 20).

(9) The first pulse sequence is composed of odd-numbered high-frequency pulses, and the second pulse sequence is composed of even-numbered high-frequency pulses less than the high-frequency pulses of the first pulse sequence.
When the first high-frequency pulse in one pulse sequence has the opposite phase, an appropriate waiting time is provided immediately after the application of the inversion pulse, and the inversion pulse and the first pulse sequence have the same phase. Inspection equipment using nuclear magnetic resonance
See Figure 21).

(10) The first pulse sequence is composed of odd-numbered high-frequency pulses, and the second pulse sequence is composed of even-numbered high-frequency pulses less than the high-frequency pulses of the first pulse sequence.
When the first high-frequency pulse in one pulse sequence has the same phase, an appropriate waiting time is provided immediately before the application of the inversion pulse, and the phase difference between the inversion pulse and the first pulse sequence becomes π / 2. An inspection apparatus using nuclear magnetic resonance (see FIG. 22).

(11) The first pulse sequence is composed of even-numbered high-frequency pulses, and the second pulse sequence is composed of more odd-numbered high-frequency pulses than the first pulse sequence has.
When the first high-frequency pulse in one pulse sequence has the opposite phase, an appropriate waiting time is provided immediately before the application of the inversion pulse, and the phase difference between the inversion pulse and the first pulse sequence becomes π / 2. An inspection apparatus using nuclear magnetic resonance (see FIG. 23).

(12) The first pulse sequence is composed of even-numbered high-frequency pulses, and the second pulse sequence is composed of more odd-numbered high-frequency pulses than the first pulse sequence has.
When the first high-frequency pulse in one pulse sequence has the same phase, an appropriate waiting time is provided immediately before the application of the inversion pulse, and the inversion pulse and the first pulse sequence have the same phase. Inspection equipment using nuclear magnetic resonance
See Figure 24).

〔The invention's effect〕

As described in detail above, according to the present invention, after applying a pulse sequence composed of a plurality of sufficiently short high-frequency pulses separated by a pulse interval time of an appropriate length as an excitation pulse, the pulse sequence is inverted after the pulse interval time. Since a pulse is applied and the pulse sequence is applied again, the phase error due to the non-uniformity of the static magnetic field can be corrected, and the reduction of the signal to be measured and the solvent suppression effect can be reduced. Also, since the flip angle is set so that the nuclear magnetization having the resonance frequency at the center frequency of the excitation band falls in the excitation plane when the above-mentioned pulse sequence is continuously applied twice, the observation signal of the minute compound in the excitation band is reduced. Will be the largest.

Further, when the pulse sequence is composed of odd-numbered high-frequency pulses, the high-frequency pulse and the inverted pulse of the pulse sequence have a phase difference of π / 2, and when the pulse sequence is composed of even-numbered high-frequency pulses, the pulse sequence is composed of even-numbered high-frequency pulses. Since the high-frequency pulse and the inverted pulse have the same phase, they can be applied to any pulse sequence.

[Brief description of the drawings]

FIG. 1 is a timing chart of application of a high-frequency pulse according to an embodiment of the present invention, FIG. 2 is a timing chart of application of a high-frequency pulse showing an example of a conventional method, and FIG. FIG. 4 is a diagram showing an example of an inspection apparatus using nuclear magnetic resonance according to one embodiment of the present invention, and FIG. 5 is a diagram showing a nuclear magnetization vector of a minute compound in one embodiment of the present invention. Locus, FIG. 6 (a)-
(D) shows the transverse magnetization according to the conventional method when the static magnetic field is nonuniform, and FIGS. 7 (a) to (d) show the transverse magnetization according to the embodiment of the present invention when the static magnetic field is nonuniform. Is a timing chart of applying a high-frequency pulse in another conventional method, and FIG.
FIG. 11 is a timing chart of the application of a high-frequency pulse according to another embodiment of the present invention. FIG. 10 is a trajectory of a nuclear magnetization vector of a microscopic compound when the embodiment of FIG. 9 is executed.
(D) is the transverse magnetization according to the conventional method when the static magnetic field is non-uniform, and FIGS. 12 (a) to (d) are the transverse magnetization according to the embodiment of the present invention when the static magnetic field is non-uniform. 24th
FIG. 10 is a timing chart of a high-frequency pulse application according to another embodiment of the present invention. 1: Static magnetic field generating coil, 2: Gradient magnetic field generating coil, 3: Inspection object, 4: Sequencer, 5: Gradient magnetic field driver, 6: High frequency transmitter, 7: High frequency modulator, 8: High frequency amplifier, 9: High frequency transmission , 10: receiver, 11: amplifier, 12: phase detector, 13: AD converter, 14: CPU, 15: storage medium.

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-1-156647 (JP, A) JP-A-3-90131 (JP, A) JP-A-63-212337 (JP, A) (58) Investigation Field (Int.Cl. ⁷ , DB name) A61B 5/055 JICST file (JOIS)

Claims (9)

(57) [Claims] An inspection apparatus using nuclear magnetic resonance for detecting a nuclear magnetic resonance signal of an inspection object placed in a space to which a static magnetic field is applied. Applying a first pulse sequence consisting of RF pulses having a flip angle ratio according to a term distribution to the object to be inspected; applying an inverted RF pulse to the object to be inspected; having a constant pulse interval and sequentially inverting the phase And applying a second pulse sequence composed of RF pulses having a flip angle ratio according to a binomial distribution to the test object, and measuring a transverse magnetization signal generated from the test object. A first addition value that is a sum of absolute values of flip angles of the respective RF pulses of the first pulse sequence, and a sum of absolute values of flip angles of the respective RF pulses of the second pulse sequence. With the second addition value An inspection apparatus using nuclear magnetic resonance, wherein the sum is π / 2. 2. An inspection apparatus using nuclear magnetic resonance for detecting a nuclear magnetic resonance signal of an inspection object placed in a space to which a static magnetic field is applied. Applying a first pulse sequence consisting of RF pulses having a flip angle ratio according to a term distribution to the object to be inspected; applying an inverted RF pulse to the object to be inspected; having a constant pulse interval and sequentially inverting the phase And applying a second pulse sequence composed of RF pulses having a flip angle ratio according to a binomial distribution to the test object, and measuring a transverse magnetization signal generated from the test object. A first addition value which is a sum of absolute values of flip angles of respective RF pulses of the first pulse sequence and a sum of absolute values of flip angles of respective RF pulses of the second pulse sequence. Some second addition value is π / An inspection apparatus using nuclear magnetic resonance, characterized in that: 3. The inspection apparatus using nuclear magnetic resonance according to claim 1, wherein each of the first and second pulse sequences is composed of an even number of RF pulses having the same phase. After a predetermined time interval from the end of the pulse sequence, the inverted RF pulse and the second pulse sequence are continuously applied, and the inverted RF pulse is the first and second pulse sequences. An inspection apparatus using nuclear magnetic resonance, wherein the inspection apparatus has the same phase as one of the RF pulses. 4. The inspection apparatus using nuclear magnetic resonance according to claim 1, wherein each of the first and second pulse sequences is composed of an odd number of RF pulses having the same phase, and After a predetermined time interval from the end of the pulse sequence, the inverted RF pulse and the second pulse sequence are continuously applied, and the phase of the inverted RF pulse and the first and second pulses are applied. An inspection apparatus using nuclear magnetic resonance, characterized in that the phase of each RF pulse in the series differs by 90 degrees. 5. The inspection apparatus using nuclear magnetic resonance according to claim 1, wherein the first pulse sequence is composed of an odd number of RF pulses, and the phase of the first RF pulse of the second pulse sequence is The first
The second pulse sequence is composed of an even number of RF pulses, and the inverted RF pulse is one of the first and second pulse sequences. An inspection apparatus using nuclear magnetic resonance, wherein the inspection apparatus has the same phase as the phase of the RF pulse. 6. The inspection apparatus using nuclear magnetic resonance according to claim 1, wherein the first pulse sequence is composed of an odd number of RF pulses, and the phase of the first RF pulse of the second pulse sequence is The first
The second pulse sequence is composed of an even number of RF pulses, and the phase of the inverted RF pulse and each of the first and second pulse sequences are the same. An inspection device using nuclear magnetic resonance, characterized in that the phase of the RF pulse is different by 90 degrees. 7. The inspection apparatus using nuclear magnetic resonance according to claim 1, wherein the first pulse sequence comprises an even number of RF pulses, and a phase of a first RF pulse of the second pulse sequence is: The first
The second pulse sequence is composed of an odd number of RF pulses, and the inverted RF pulse is in phase with the phase of any RF pulse of the first pulse sequence. An inspection apparatus using nuclear magnetic resonance, having the same phase. 8. The inspection apparatus using nuclear magnetic resonance according to claim 1, wherein the second pulse sequence is composed of more than the number of RF pulses of the first pulse sequence, and the inverted RF The pulse keeps a time interval from the end of the first pulse sequence,
An inspection apparatus using nuclear magnetic resonance, which is applied immediately before the start of application of the second pulse sequence. 9. The inspection apparatus using nuclear magnetic resonance according to claim 1, wherein the second pulse sequence is composed of RF pulses equal to or less than the number of RF pulses of the first pulse sequence, and An inspection apparatus using nuclear magnetic resonance, wherein a pulse is applied immediately after the end of the first pulse sequence.