JPS63143043A - Region selective nuclear magnetic resonance data lead-out method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention: "Industrial Application Field" This invention applies to a nuclear magnetic resonance diagnostic apparatus that analyzes and diagnoses components contained in a subject using nuclear magnetic resonance. A region-selective nuclear magnetic resonance information derivation method for deriving nuclear magnetic resonance information from.

"Prior Art" As a technique for performing diagnosis using nuclear magnetic resonance (hereinafter referred to as NMR), an NMR imaging method has been commonly used in the past. However, the objects for which NMR imaging can be performed within practical time are limited to substances that exist in large quantities in living organisms, such as water and fat protons ('H), fluorine ("F), and sodium (!3Na). Furthermore, chemical shift information cannot be extracted using conventional methods.

Chemical shift imaging is a special imaging method, but at present it is only capable of separating water and fat, and it is difficult to obtain high-resolution spectra of trace metabolites and phosphorus ("P").

On the other hand, various methods are being explored to obtain high-resolution spectra from local areas of the subject. The first one tried was T.
MR (Topical Magnetic Re5on)
ance), a specific magnetic field strength is set only in a certain local region within the space (subject), and a high-frequency electromagnetic field pulse ( (hereinafter referred to as RF pulse) is applied. However, with this TMR method, it is difficult to obtain a high-resolution spectrum because signals from nuclear spins near the selected region create false signals, and the next method attempted uses a surface coil. This is a method of obtaining information from a local area by appropriately controlling the shape of the coil and the intensity of the RF pulse, but this method can only obtain signals from the surface of the object. DRES combining surface coil and gradient magnetic field
S (Depth Re5olve 5pectrosc
There is also a method called ``opy'', but it has the disadvantage that the selected area becomes planar and the signal becomes stronger closer to the surface. In fact, the VSE method (J
, Magn, Re5on,, 56, 350-3
54 (1984), JP-A No. 59-645 @), ■
R0J, 01J DIDGE et al.'s 1515 method (J, Mag
n, Re5on, 66.283-294 (1986
),),■P,R.

5PAR5 method of LIIYTEN et al. (J, Magn.
Re5on, 67, 148-155 (1986)
,”) and ■P,A,BOTTOM[,EY localization N
Method of implementing MR chemical shift spectroscopy (JP-A-59-1
07246).

The pulse sequence in the VSE method (①) is as shown in Figure 10, with a non-selected 90゜ pulse and a selected 4 pulse sandwiching it.
A slice in one direction is selected by a set of 5° +45° pulses (i.e., a non-selective 90° pulse is inserted in the center of the selected tR90" pulse), and the inner spins have components in the Z or -Z direction. In other words, a static magnetic field is applied in the Z-axis direction, and a magnetic field GX is applied to the X-axis (around the When given to the specimen, the sharp 9
When a 0° pulse is applied to a subject, since this 90° pulse has many frequency components, specific spins are excited in any part of the subject on the X axis, that is, non-selective excitation is performed. ° Since the +45° pulse has almost only specific frequency components, only the section cut at a specific position on the X-axis (selected section) is excited first, that is, 90°
The inverted spins are further inverted by 90 degrees, and from the initial state, the spins are inverted by 180 degrees (in the Z-axis or -Z-axis direction), and enter a non-excited state. On the other hand, since the gradient magnetic field Gx is applied for a relatively long time, the excited spins (spins tilted by 90°) other than the selected plane (portion) rotate according to the strength of GK at that position. The spin axis rotates, and each spin in the non-selected portion as a whole is rotated separately, resulting in a so-called spoiled state, and the combined value of the free induction signal as a whole becomes zero.

If the same thing is done for the Y-axis gradient magnetic field and the Z-axis gradient magnetic field, the spin direction of each of these X-axis, Y-axis, and Z-axis will be the Z-axis or -Z-axis, and all other spins in the non-selected portion will be It will be spoiled. Thereafter, when a 90'' excitation pulse is applied, a free induction signal (hereinafter referred to as Fltl signal) from the selected portion is observed.

The pulse sequence in the 15IS method (2) is as shown in FIG. In this case, the partial selection sequence in VSH in (2) has been changed to a 180° pulse for selection of the X, Y, and Z axes. In other words, while applying the X-axis gradient magnetic field GK, 18
Give a 0° pulse to tilt a specific spin in a vertical cross section in the -Z axis direction at a selected position on the X axis.
After doing the same for the axis and the Z axis, a 90° excitation pulse is applied. However, as shown in Figure 12, the sequence is performed eight times, and the spin is not reversed (18
0'' pulse is not applied), ON indicates spin reversal, and the FID signal obtained in this 8-time sequence is
Addition is performed using the signal addition coefficient shown in FIG. In other words, the first time only excite the entire body with a 90° pulse, and the FID signal at that time is positive, and the second time, a 180° pulse is applied for X-axis selection, and each 180° pulse is applied for Y-axis selection and Z-axis selection. Instead, a 90° excitation pulse is applied (this is applied every time), and the FID signal obtained at this time is made negative. Thereafter, by adding the eight FID signals obtained in the eight sequences in the same manner with the given polarity, the signals in the non-selected portion cancel each other out and are not output, and the X-axis.

The FID signals of only the portions (selected portions) that intersect with the selected planes of the Y-axis and the Z-axis are added and output. In addition, in this method, the spin rotation angle (flip angle) by each 180° pulse of x, y, and z is 180°.
It has been theoretically shown that at any angle α, β, or γ, all signals from outside the selected portion are canceled.

■ The pulse sequence in 5PARS is the 13th
As shown in the figure, this can be said to be an improved version of the VSE shown in (3). That is, the non-selective 90° pulse of VSE in (2) and the selective 45° +45° pulse for slice selection are separated, and the non-selective 180° pulse is inserted between them. By making these three pulse intervals equal, a spin echo occurs at the center of the selected 90° (45°-45°) pulse, correcting for phase variations due to B, non-uniformity, and chemical shift. Note that non-selection 18
The gradient magnetic field pulse Gx1 immediately before the 0° pulse is selected from selection 90.
This is for phase compensation of the slice selection gradient magnetic field pulse aXS applied together with the ° pulse.

■ To further elaborate on 5PAR3, non-selection 90
The entire subject is excited by the X pulse, and each of the excited spins has a phase difference over time in accordance with the two-difference frequency difference. When a 180°y pulse is given,
The spins are exchanged within the plane of rotation around the phase center of each spin, and the one that was rotating fastest until then becomes the position of the slowest spin. Therefore, when the time interval between these 90°
When a tx pulse is applied, only the spins on the selected plane (slice plane) become in the Z-axis or -Z-axis direction, and the other excited spins are in the G direction. The phase is scattered.

If you do the same for the Y-axis and the Y-axis, the spin of only the part that intersects the three selected planes will be
This is in the axial direction, and when a 90° excitation pulse is applied, only this selected portion is excited.

There are two methods described in JP-A-59407246 (1), and the pulse sequence of the first method is shown in FIG. This method involves applying a high-frequency pulse that saturates a certain selected area outside the chamfer under a first gradient magnetic field G8, in other words, making the spin apparently invisible, and then applying a high-frequency pulse that saturates a selected area outside the chamfer. Under A, a 90' selection pulse is applied to excite a plane perpendicular to a specific point on the Y axis in the unsaturated plane (selected plane), and then under a third gradient magnetic field G, x, '180'' selection pulse is applied, only the spins on the plane orthogonal to the specific point on the Y axis are replaced with leading spins and lagging spins, and 3
A spin echo signal at the intersection of the two selected planes is extracted.

The pulse sequence in the second method of (2) is shown in FIG. 15. In this case, first, a 90° selection pulse is used to
0-order 18 to excite spins in the selected slice plane
The 0° selection pulse is repeated to spoil spins other than the selected portion in other selected slices, and then spin echo signals from the intersections (selected portions) of the three selected slice planes are observed.

[Problem that the invention seeks to solve]

These conventional techniques have the following problems.

In the VS2 method (2), it is necessary to apply a non-selective 90" pulse in a gradient field. To do this, the pulse width must be short enough to widen the generated frequency range, and it is necessary to must be excited in response to each magnitude of the gradient magnetic field, and in order to transmit this narrow 90° pulse, the output of the transmitter also needs to be large, and the peak value also affects the subject, especially the human body. This results in the application of a high high frequency power of
TI) cannot be ignored in some cases. Also, if there is an error in the pulse, it will be greatly affected.

In the 1515 method (2), the FID signal actually observed each time has many signals superimposed on it from areas other than the parts that should be selected, resulting in a signal with a high level as a whole. Although an expensive AD converter with a large dynamic range must be used as an AD converter, there is a limit to this, and the S/N ratio of the resulting signal from the selected area deteriorates.

In the 5PAR3 method (2), the number of high-frequency pulses used is large compared to other conventional methods, so the time from the first 90° Under the influence of relaxation, the FID signal deteriorates. Also, a non-selection pulse 90'x.

Since a large number of 180°y angles are used, there is a drawback that the high frequency power applied to the subject also increases. Furthermore, since it is a combination of multiple pulses, the error of each pulse is greatly affected.

The first method described in Japanese Patent Application Laid-Open No. 59-107246 uses a powerful long saturated high-frequency pulse with a frequency component selected to irradiate the entire surface other than the selected plane, so it is absorbed by the subject. The high frequency power generated also increases, which is undesirable. Furthermore, in the second method, in order to observe the spin echo signal, there is a limit to the time from the first 90° selective pulse in FIG. 13 to the reception of the desired spin echo signal, and this cannot be shortened. Furthermore, since no boiling is performed in the Z direction, there is a risk that signals from areas other than the selected portion may not be removed. A 90° pulse component occurs at the rise and fall of a 180° pulse, making it difficult to obtain a correct signal. In addition, components of the material structure with short T2 are attenuated and cannot be observed.

As mentioned above, conventional region-selective nuclear magnetic resonance spectroscopy has several methods, but because it uses spin echo, it is impossible to observe molecules and tissues with short T2, and
When saturating outside the region with a pulse train, it is difficult to adjust each pulse, and interference between pulses becomes a problem.

On the other hand, by analyzing the behavior of nuclear spins in detail, using an amplifier with good linearity in the transmission system that generates high-frequency electromagnetic field pulses, and providing a feedback mechanism, the center frequency region can be restored to its original state, and the nuclear spins on both sides can be We were able to design a soft pulse that tilts the angle almost 90 degrees. If this pulse is used, only one pulse needs to be adjusted, making it very convenient in practice.

"Means for Solving the Problem" In this invention, a gradient magnetic field is applied at a certain timing, then RF pulse waveform data is read from the memory, and the read output is converted to an analog signal via a DA converter. Send it as a modulation signal to the amplitude modulator. The high-frequency electromagnetic field pulse obtained in this way tilts the nuclear spins by 90° except in a specific region, and then a gradient magnetic field pulse called a boiling pulse is applied so that the integral values do not match, thereby excluding the specific region. The nuclear spin of the part that is saturated is saturated. Finally, by adding a pulse with a smooth envelope (soft pulse) or a pulse with a sharp envelope (hard pulse) that tilts the nuclear spin by a certain angle θ, the free induction decay signal of the nuclear spin in the selected region can be obtained. can.

According to this invention, it is possible to observe molecules and tissues with short T2 (transverse relaxation), and when observing weak signal areas, the dynamic range is not narrowed (and only one pulse is required). Therefore, adjustment is easy.

Embodiment In this invention, one important point is the waveform of the saturation pulse applied before the read pulse.

Examples of some of the waveforms are shown in FIG.

A in the same figure shows the cosine modulation 5INC function f (t) =A-g(t) ・cos(:'πy,
t) H5in(2πνit)/l where Geo is the carrier frequency of the RF pulse, and g (L) is the quantitative number.

Figure B shows the sine modulation 5INC function f (L) =A-g(t) ・5in(2πν+t
) ・5tn(2πνzt)/C in the same figure is an improved version of B in the same figure, and Gaussia is added to the sine modulation 5INC function.
This diagram, which is applied with an n-type window function, is also an improved version of Figure B, and the amplitude (height) and width (time width) of the 5INC function are appropriately controlled and sine modulation is applied. It is something. The saturation pulse may also be a short hard pulse train such as 1331 pulses, where "3" is the peak value 3.
"3" represents a positive pulse with a peak value of 3.

si, = 1.2 sit = 900H2, 13+sec sine change j1!5 INC pulse, gradient magnetic field 0.035 G
FIG. 2 shows the distribution of transverse magnetization when auss/cm is applied. The horizontal axis is the X coordinate, and the nuclear spins of ±1 near x=10 am return to their original state, while the others are tilted by 90°.

The range in which the nuclear spin returns to its original state (referred to as the non-excited range) may be controlled by using a gradient magnetic field or by an RF pulse waveform. That is, if the gradient magnetic field is made stronger, this non-excited range becomes narrower, and conversely, if it is made weaker, this non-excited range becomes wider. Similarly, when a sine modulation 5INc function is used, the non-excitation range will become narrower if si,/v2 is made smaller (closer to l), and conversely, if it is made larger, this range becomes wider. The position within this range can be moved by changing the frequency of the carrier wave. Note that the sine-modulated 5 INC pulses under the above conditions were subjected to fast Fourier transform (
If you do FFT), you can easily find something similar to that shown in Figure 2, but the behavior of the nuclear spin becomes nonlinear around 90°, and Fourier transform causes errors. The behavior of nuclear spin is Bloc
Since it follows the k equation, it is best to obtain the optimal waveform by computing and simulating it over time.

FIG. 3 shows an example of a pulse sequence implementing the first embodiment of the invention. Apply any of the various saturation pulses described above to x, y, and z gradient magnetic fields G.

When applied together with G3, only the 6I region that intersects each of the three selected planes (non-excited range 1ffl in Figure 2) is made into a non-excited state, and the rest are made into an excited state with the nuclear spin tilted by 90 degrees. These are boiled with a boiling gradient magnetic field pulse, and then a reading pulse is given to generate a free induction decay signal from the intersection area, the signal is detected, the detection output is converted to a digital signal, and then Fourier transform is applied to the selected area (crossover area). Obtain high-resolution chemical shift spectra from regions).

The above operation will be schematically explained with reference to FIG. When a rectangular parallelepiped object is used as the object 11, the saturation pulse Pal and the gradient magnetic field G create a cross section perpendicular to the X-axis at a selected position on the X-axis (diagonal lines are indicated) as shown in FIG. The nuclear spin returns to its original state (unexcited area) 12 only, that is, it becomes a non-excited range, and the hatched area 1 on both sides of it returns to its original state.
The nuclear spin of 3.14 is flipped by 90°. After that, by applying a spooling gradient magnetic field G, , G□, G,3, the phase of each nuclear spin in the shaded area 13.14 is dispersed, and the composite value of the free induction signal generated from these becomes zero,
In other words, the nuclear spin is in a saturated state, that is, in a spoiled state. At this time, in the selected cross section 12, the nuclear spin is not inverted, so the sboiling gradient magnetic field G,
,, G□+ Not affected by G111.

Next, when a saturation pulse P and a gradient magnetic field G are applied, Y
Only the Y-axis and the perpendicular cross section 15 at a predetermined position on the axis are non-excited ranges, and the nuclear spins are tilted by 90° in the shaded regions 16 and 17 on both sides thereof.

In FIG. 4B, only the previously selected section 12 is shown. Here, the Sboiling gradient magnetic field G. ,G□
, G□, the phases of the nuclear spins are scattered only in the shaded regions 16° and 17.

Further, after that, by applying the saturation pulse Ps3 and the filler magnetic field G2, only the cross section 18 perpendicular to the Z axis at a predetermined position on the Y axis becomes a non-excited range, and the hatched area 19 on both sides thereof becomes a non-excited range.
．． In 20, only the shaded area 19.20 is skived by the zero-order skiboiling magnetic field G, , G□, Go in which the nuclear spin is tilted by 90 degrees.

Only the region 18 where the cross sections 12 and 15° 18 selected by the above process intersect each other is in a state in which the nuclear spins are not tilted, and when a read pulse is applied to the subject 11 in this state, the nuclear spin is only in the region 18. Spin tilts 90 degrees, area 18
A free induction signal is generated only from.

For example, s+=1.2 sz=900Hz, s m5et
sine-modulated 5INC pulses P 3++ P sz,
P ss and a gradient magnetic field G of 0.07 Gauss/cm
When w, Gv, and Gz are applied as shown in FIG. 3, a cubic region 18 with −side l] is selected. The spoiling gradient magnetic field pulses cxy, GYl, and czs inserted in between at this time are each 0.5G as the first spoiling pulse (the one immediately after Ps+).
auss/cm, 4 m5ecs immediately after the second boiling pulse CPst) is 0.6 Gauss/c
Im, 4 m5ecs third boiling pulse is 0,
7 Gauss/as, 4 m5ec.

There is no particular need to change the order of direction selection, and the waveform of the last read pulse may be rectangular or 5ING waveform.
It may be ussian. It is preferable to find the optimum value for the angle at which the read pulse tilts the nuclear spin depending on the edge-turning time, but an angle other than 90° may also be used. Spin echoes may be detected in the selected region 18 in the imaging sequence after the read pulse.
A high-resolution chemical shift spectrum can also be obtained after confirming the position and range of . That is, this technique can also be used as a partial magnification imaging method.

FIG. 5 shows an example of a pulse sequence for realizing the second embodiment of the present invention.
Apply a gradient magnetic field G8 in the Y direction, disturb the phase with spoiling/gradient magnetic field pulses, and apply a gradient magnetic field G8 in the Z direction.
Slice like INC waveform or Gaussian waveform.
A read pulse is applied that corresponds to a waveform with a unified profile, that is, the gradient magnetic field G2, and selectively excites only a certain range in the Z-axis direction, for example, region 18. At this time, free induction signals of each frequency are obtained from the region 18 according to each position on the Y axis. After this, as in the previous method, the detection signal is converted into a digital signal and subjected to Fourier transformation to obtain a high-resolution chemical shift spectrum. 4m5ec for read pulse.

7501 (5 INC waveform of z 0.2 Gauss/c
m gradient magnetic field G.

If applied together, the slice thickness will be approximately lea, so
By adding this pulse to the above conditions, it is possible to select a 1-cubic area. This series can also be used as a spin echo, and can also be used as a partial magnification imaging method.

Both of the above-mentioned methods of the two inventions use phase cycling, in which a plurality of pairs of RF pulse phase and data acquisition phase are created and rotated in sequence.
) technique to perform the averaging.

In addition, in this sequence, information on spin coupling can be obtained in addition to information on chemical shifts, and by applying a high-frequency electromagnetic field or pulse train for decoupling to this sequence, it is possible to obtain information on NOE (nuclear overparts\Wouser effect). You can get information. If the 180° inversion pulse is applied first, it is possible to obtain the information of T+ (1111 sum), and if the CPMG pulse sequence is applied after the read pulse, the information of T+ (1111 sum) can be obtained.
2 (transverse relaxation) [Also, it can be used together with a solvent suppression pulse to detect trace substances. ] As described above, according to the present invention, various types of nuclear magnetic resonance information can be extracted from a certain selected area. Further, by using the method shown in FIG. 5, it is also possible to select another region using the relaxation waiting time and extract the above information, that is, high-resolution chemical shift information. In addition, in the examples, examples have been described with the case of proton (1H) in mind, but this is Ilp, 13C1' ``F + '' 3N
The same method can be applied to the nuclear spins of the a-isocenter.

As mentioned above, various types of saturation pulses can be used, and an example of the hard pulse train is 1.
331 pulse is shown as an example, but other hard pulse trains with a narrow central non-excitation region include 1551, 1771,
15.4.5.41 etc. can be used. This last pulse train 15.4, 5.41 is, as shown in Fig. 6, a positive pulse with an amplitude of 1, followed by a negative pulse with an amplitude of 5.4 2τ later, and a positive pulse with an amplitude of 5.4 after that τ. And part 2
After τ, a negative pulse of amplitude l occurs. The spectrum of the pulse train is shown in FIG. FIG. 8 shows a case where an example of the pulse sequence of the present invention using the saturation pulse of such a hard pulse train is applied to the pulse sequence of FIG. 3.

Next, an example of an apparatus for carrying out the method of the present invention will be described with reference to FIG. The electromagnet 32 is driven at the lock timing from the timing control unit 1 31, and the main electromagnet 33 including the shim coil is controlled to maintain a constant main static magnetic field on the subject. From the timing control section 31 to the timing generation section 34
is activated, and the timing generator 34 outputs RA? 1 35, the digital storage of the saturation pulse waveform and the read pulse waveform is read out at a predetermined timing, and the read digital signal is converted into an analog signal by the DA converter 36. The amplitude modulator 37 amplitude-modulates the carrier wave from the synthesizer 3 using this analog signal. This modulated output is supplied to a transmitting/receiving coil 42 through a matching and switching device 41, and an RF pulse is emitted. The output frequency of the synthesizer 38 is set by the timing control 31, a local signal from the synthesizer 38 is also given to the receiver 43, and the free induction signal (FID signal) from the subject received by the transmitting/receiving coil 42 is sent to the matching/switching device. 41 and is received and amplified by a receiver 43. This FID signal is processed by the data processing computer 44 via the timing control section 31. The timing control unit 31 supplies the timing waveform to the gradient magnetic field current amplifier 45 and its output gradient magnetic field coil 46, and applies gradient magnetic fields for various plane selections and boiling gradient magnetic fields to the subject at the required timing. do.

"Effects of the Invention" As described above, according to the present invention, a rectangular parallelepiped region of any size at any position within the subject is selected, and ATP (adenosine 3), which plays an important role in the living body, is
It is possible to obtain high-resolution chemical shift information of trace metabolites such as phosphate (phosphocreatine), PCr (phosphocreatine), and lactic acid, providing a powerful tool for research and diagnosis in physiology and clinical medicine.

When region-selective spectroscopy is performed on an elongated object such as a human body, the embodiment shown in FIG. 3 has the effect of greatly changing the pulse waveform in only one direction. However, in the embodiment shown in FIG. 5, only one type of saturation pulse is required.
The last read pulse is the 5I used in normal imaging.
It is practical because NC pulses and Gaussian pulses can be used.

[Brief explanation of the drawing]

Figure 1 is a waveform diagram showing examples of various saturation pulses used in this invention, Figure 2 is a diagram showing magnetization distribution when the pulse in Figure 1 B is applied with a gradient magnetic field, and Figure 3 is a diagram showing the invention. the first of
FIG. 4 shows an example of a pulse sequence in the embodiment of
The figure is a perspective view showing the state of response to the application of each pulse in Fig. 3, Fig. 5 is a view showing an example of the pulse sequence in the second embodiment of the present invention, and Fig. 6 is a diagram showing the state of response to the application of each pulse in Fig. 3. FIG. 7 is a diagram showing the frequency spectrum of the pulse in FIG. 6, FIG. 8 is a diagram showing a pulse sequence of an example of the present invention using a hard pulse train as a saturation pulse, and FIG. 9 is a diagram showing the pulse sequence of the invention. A block diagram showing an example of an apparatus for carrying out the method, FIG. 1O is a diagram showing the sequence of the conventional VSE method, FIG. 11 is a diagram showing the sequence of the conventional rsts method, and FIG. 12 is a diagram showing the sequence of the conventional 1SIS method. Figure 13 is a diagram showing the sequence of the conventional 5PAR5 method, and Figure 14 is a diagram showing the sequence of the conventional 5PAR5 method.
FIG. 15 is a diagram showing the sequence of the first method described in Japanese Patent Laid-Open No. 107246/1983. Spear 1 Figure 2 2173 Figure 4 Figure 5 Figure O 67 5.4 i7 Figure 8 Figure 9cf 90° 90'90"([2"
) [4Gx G G2 11th Z Sai12 Recording 13 Figure 7i714 Figure 15

Claims (2)

[Claims] (1) Place a subject in a static magnetic field, irradiate the subject with a high-frequency electromagnetic field, and excite specific nuclear spins of the subject,
In nuclear magnetic resonance diagnostic equipment that detects the nuclear magnetic resonance signal and analyzes the components contained in the above-mentioned object, high-frequency electromagnetic After applying the field pulse, the nuclear spins are returned to their original state, and for nuclear spins that have a resonant frequency in the region outside that region, a high-frequency electromagnetic field saturation pulse is applied that turns the nuclear spins by 90 degrees after applying the high-frequency electromagnetic field pulse, and the intensity is the first. The saturation pulse is simultaneously applied by applying a gradient magnetic field whose intensity is tilted in a second direction intersecting the first direction; Applying a gradient magnetic field having a gradient in strength in a third direction intersecting the second direction in a different plane, applying the saturation pulses simultaneously, and between each of the saturation pulses and after the last saturation pulse, The first and second waves disturb the phase of the nuclear spin, respectively.
, a gradient magnetic field in the third direction is applied simultaneously to eliminate all the effects of nuclear spins except for the nuclear spins in the rectangular parallelepiped region at the intersection of the three planes perpendicular to the first, second, and third directions. After that, a high-frequency electromagnetic field pulse is applied to excite the nuclear spins having the resonant frequency of the center frequency by tilting them at a certain angle, and a region selection is performed to obtain free induction decay signals only from the nuclear spins within the rectangular parallelepiped region. Nuclear magnetic resonance information derivation method. (2) Place a subject in a static magnetic field, irradiate the subject with a high-frequency electromagnetic field, and excite specific nuclear spins of the subject;
In nuclear magnetic resonance diagnostic equipment that detects the nuclear magnetic resonance signal and analyzes the components contained in the above-mentioned object, high-frequency After the electromagnetic field pulse is applied, the nuclear spins are returned to their original state, and for the nuclear spins that have a resonant frequency in the region outside that region, after the above-mentioned high-frequency electromagnetic field pulse is applied, a high-frequency electromagnetic field saturation pulse that tilts the nuclear spins by 90° is applied. The saturation pulses are applied together with a gradient magnetic field whose intensity is inclined in one direction, and then the saturation pulse is simultaneously applied by applying a gradient magnetic field whose intensity is inclined in a second direction that intersects the first direction, and each of the saturation pulses is Immediately after, the first wave that disturbs the phase of the nuclear spin
, gradient magnetic fields in the second and third directions are applied simultaneously, and after the second application of the gradient magnetic fields in the first, second and third directions, a surface different from the first and second directions is applied. Applying a gradient magnetic field whose strength changes in a third intersecting direction,
Simultaneously apply a high-frequency electromagnetic field pulse that tilts nuclear spins having a resonant frequency of the above center frequency at a certain angle, and within a rectangular parallelepiped area at the intersection of three planes perpendicular to each of the first, second, and third directions. A region-selective nuclear magnetic resonance information derivation method that obtains free induction decay signals only from nuclear spins.