JPH0316853B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a nuclear magnetic resonance imaging device (hereinafter referred to as NMR), and particularly relates to a nuclear magnetic resonance imaging device (hereinafter referred to as NMR), and in _particular ,
This invention relates to improvements in means for obtaining calculation images of T ₂ and proton density ρ.

(Prior art) Longitudinal relaxation time T ₁ , which is considered to be medically useful, has been measured from images measured by NMR imaging devices.
There is a technique to obtain an image related to the value (T ₁ image) and an image related to the transverse relaxation time T ₂ value (T ₂ image).

(Problems to be Solved by the Invention) However, the T ₁ image and the T ₂ image have been obtained using different methods as follows.

For example, the T ₁ image is calculated as follows. Inversion recovery method (hereinafter abbreviated as IR method) as shown in Figure 5
and the IRSE method, which is a combination of the spin echo method (hereinafter referred to as SE method), and
The saturation recovery method as shown in the figure
One original image is obtained using the SRSE method, which is a combination of Recovery (hereinafter abbreviated as SR method) and SE method, and calculations are performed using these two images and an approximation formula for signal strength.

As shown in Figure 6, the SRSE method is a pulse sequence in which an echo signal is obtained by applying a 90° pulse and then a 180° pulse, and the time from the 90° pulse to the center of the echo signal is T _s , 90 The time from the application of a 90° pulse to the application of a 90° pulse in the next view is T _r .

Furthermore, as shown in Figure 5, the IRSE method is a pulse sequence in which a 180° pulse for inversion recovery is applied before each 90° pulse of the SRSE method shown in Figure 6. T d is the time from the application of the 180° pulse to the application of the 90° pulse, T _s is the time from the 90° pulse to the center of the echo signal, and T _s is the time from the 90° pulse to the center of the echo signal.
T _r is the time from application of a 180° pulse for recovery to application of a 180° pulse for the next view.

Theoretical formula for signal strength in the SRSE method I _SR is I _SR = Io・exp(−Ts/T ₂ ) {1−2・exp(−Tr/T ₁ +T
s/2T ₁ ) + exp (-Tr/T ₁ )} Also, the theoretical formula for signal strength in the IRSE method I _IR is I _IR = Io・exp (-Ts/T ₂ ) {1-2・exp (-Td / _T1 )
+2·exp(−Tr/T ₁ +Ts/2T ₁ )−exp(−Tr/T ₁ )}.

For this theoretical formula, here, as Tr≫T ₁ ,
If exp(−Tr/T ₁ )=0, I _SR ≒Io・exp(−Ts/T ₂ ) I _IR ≒Io・exp(−Ts/T ₂ ) {1 −2・exp(−Td/ T ₁ )} Therefore, I _IR / I _SR = 1-2・exp(-Td/T ₁ ) T ₁ = Td/ln {2I _SR / (I _SR − I _IR )} Find the T ₁ value from this formula .

When obtaining a T ₂ image, for example, multiple echoes can be obtained using the CPMG method described on pages 570 to 576 of the June 1984 issue of the publication "Image Information (M)" (Vol. 16 No. 11). T ₁ and ρ are removed from the data and the T ₂ value is determined by the least squares method.

In addition, in the CP method, which allows multiple echo data to be taken out continuously in one data collection to obtain the _T2 value, if the length of the applied pulse is incomplete, the error will increase as the echoes are acquired. However, the pulse sequence called CPMG method solved this problem by applying a ₁₈₀ ° pulse after a 90° pulse as shown in Figure 7. n
This is a pulse sequence that is applied repeatedly to generate n echoes.

Conventional methods using such techniques have the following drawbacks.

(1) The T ₁ image and the T ₂ image are obtained separately, and the calculation images of T ₁ , T ₂ , and ρ cannot be obtained at the same time.

(2) Exact values cannot be determined because approximate formulas are used.

(3) Due to the condition of Tr #T ₁ , the Tr must be made long, and the total scan time is long.

(4) The scan parameters of the original image are not optimized, and the best calculated image cannot be found under the given conditions.

(5) There is a systematic error due to the influence of the slice shape.

In view of these points, an object of the present invention is to provide an NMR imaging device that can simultaneously obtain highly accurate T ₁ , T ₂ , and ρ calculation images from a plurality of original images in a short time. It's about doing.

(Means for solving the problem) In order to achieve such an objective, the present invention devises a new pulse sequence for computational images in a nuclear magnetic resonance imaging device, and combines the IRnSE method and FRmSE method.
(FR stands for Fast Recovery method).
(n+m) images are obtained from this imaging, and T ₁ , T ₂ , and ρ images are calculated from these images, and each scan parameter in the IRnSE method and FRmSE method in this case is T ₁ in the range of interest. , T ₂ , ρ
It is characterized in that the evaluation function of the calculated image is selected to be the best.

(Example) The present invention will be explained in detail below using the drawings. FIG. 1 is a diagram showing the configuration of essential parts of an embodiment of an NMR imaging device according to the present invention. In the figure, reference numeral 1 denotes a magnet assembly, which has a space (hole) inside for inserting an object. a magnetic field coil and a gradient magnetic field coil 3 for generating a gradient magnetic field (composed of an x gradient magnetic field coil, a y gradient magnetic field coil, and a z gradient magnetic field coil configured to be able to individually generate gradient magnetic fields) An RF transmitting coil 4 that provides a high-frequency pulse to excite the spin of an atomic nucleus within the object, a receiving coil 5 that detects an NMR signal from the object, and the like are arranged.

The main magnetic field coil is connected to the static magnetic field control circuit 15, G _x ,
G _y , G _z each gradient magnetic field coil is gradient magnetic field control circuit 1
4, the RF transmitting coil is connected to the power amplifier 18, and the NMR signal receiving coil is connected to the preamplifier 19.
are connected to each other.

13 is a controller that controls the sequence of generation of gradient magnetic fields and high-frequency magnetic fields.
Performs necessary control to capture the NMR signal into the waveform memory 21.

17 is a gate modulation circuit, and 16 is a high frequency oscillator that generates a high frequency signal. Gate modulation circuit 17
appropriately modulates the high frequency signal output from the high frequency oscillator 16 using a control signal from the controller 13 to generate a high frequency pulse with a predetermined phase. This high frequency pulse is applied to the RF transmitting coil 4 through the RF power amplifier 18.

19 is a preamplifier that amplifies the NMR signal obtained from the detection coil 5; 20 is a phase circuit that phase-detects the NMR signal by referring to the output signal of the high-frequency oscillator; and 21 is a waveform that stores the phase-detected waveform signal from the preamplifier. A memory that includes an A/D converter.

11 is a computer that receives the signal from the waveform memory 21 and performs predetermined signal processing to obtain a tomographic image;
12 is a display device such as a television monitor that displays the obtained tomographic image.

Reference numeral 30 denotes an operation console, which is connected to the computer 11 and is input means for inputting various information necessary for this apparatus.

Next, the procedure for creating a calculated image in such a configuration will be explained.

Here, the novel IRnSE method according to the present invention and
An example will be described in which T ₁ , T ₂ , and ρ images are calculated from a total of 7 images, 3 images obtained by the IR3SE method and 4 images obtained by the FR4SE method, using the pulse sequence of the FRmSE method.

In addition, the IR3SE method, as shown in Figure 2,
This is a pulse sequence similar to the IRSE method, but in one view, a 180° ₍₂₎ pulse is repeatedly applied three times to obtain three echo signals. Furthermore, the FR4SE method is a method that employs a pulse sequence as shown in FIG.
That is, in the SRSE method, the last (in this case,
After obtaining the fourth echo signal, the magnetization is forcibly directed toward the main magnetic field by applying a 180° pulse, followed by a 90° pulse and a 180° pulse.
This is a multi-echo method that obtains echo signals using a pulse sequence, which is characterized by shortening the recovery time to an equilibrium state of magnetization.

(1) Pulse Sequence The pulse sequences shown in FIGS. 2 and 3 will be explained in more detail as follows.

The interval Ts ₁ between the 90° pulse and the center of the first echo signal, the interval Ts ₂ between the centers of each echo signal after the first echo signal, the interval Ts ₃ between the center of the fourth echo signal and the subsequent 90° pulse, first
180° pulse (for inversion recovery)
Interval between application of 180° pulse) and 90° pulse
Td and repetition time Tr can be selected arbitrarily. These time management is done by controller 1.
3, and the time can be set using the console 30.

180° ₍₁₎ pulse is a 180° pulse for spin reversal.
180° ₍₂₎ is a 180° pulse for spin echo, and both are 90° _-45 to reduce pulse error.
Composite pulses of 270° _-45 and 90° _-45 are used.

In the IR3SE method, the number of 180° pulses for each view is an even number.

Note that the suffix value attached to the frequency of each pulse represents the phase difference with the 90° excitation pulse, and these pulses are non-selective pulses.

The 90° excitation pulse is a selective pulse and is Gaussian modulated.

Application of such a 90° pulse to a 180° pulse is performed as follows. That is, under the control of the controller 13, the gate modulation circuit 1
A predetermined 90° pulse or 180° pulse signal obtained through 7 is applied to the RF transmitting coil 4 via the power amplifier 18 to generate an RF magnetic field to be applied to the object.

On the other hand, the gradient magnetic field is as follows.
The gradient magnetic field G _x in the x direction is a projection gradient, and a is a spoiler for eliminating noise outside the slice plane due to the 180° pulse.

The z-direction gradient magnetic field _Gz is a slice gradient, the y-direction gradient magnetic field _Gy is a warp gradient, and b is a spoiler for eliminating artifacts due to 180° pulse errors. Further, c is a spoiler for removing correlation between views.

Application of each gradient magnetic field is controlled by a controller 13.

Each echo signal generated by the above pulse sequence is detected by the receiving coil 5.
The spin echo signal detected by the receiving coil is
The signal is stored in a waveform memory 21 via a preamplifier 19 and a phase detection circuit 20.

(2) Regarding the signal strength formula The signal strength formula for the IR3SE method is Io＝C _IR3 (T ₁ /Tr) [1−2exp(−Td/T ₁ )2exp(−Tr
/T ₁ +Ts ₁ /T ₁ t3Ts ₂ /2T ₁ ) −2exp(−Tr/T ₁ +Ts ₁ /T ₁ +Ts ₂ /2T ₁ )+2exp(−T
As r/T ₁ + Ts ₁ /2T ₁ )−exp(−Tr/T ₁ )]・ρ, the first echo is Io・exp(−Ts ₁ /T ₂ ) and the second echo is Io・exp(− Ts ₁ /T ₂ −Ts ₂ /T ₂ ) The third echo is Io·exp(−Ts ₁ /T ₂ −2Ts ₂ /T ₂ ).

Here, C _IR3 is a function representing the influence of slice shape, and is determined as follows.

Let Fn (Tr, Ts, T ₁ , T ₂ , ρ) be a signal strength expression that does not include the influence of slice shape.

(b) When the angle of inclination of magnetic north is α°, the signal strength is sina/1 + cosa・exp( −Tr/T ₁ )・Fn
(Tr ₁ , Ts, T ₁ , T ₂ , ρ)…(1).

(b) If a Gaussian 90° pulse is used,
α at a point at a distance Z from the center of the slice is α=(π/2)exp(−2 ² ) (2).

(c) If equation (1) is integrated by Z using equation (2), the signal strength including the influence of the slice shape will increase,
The following formula is obtained.

Fn(Tr, Ts, T ₁ , T ₂ , ρ)∫sin {(π/
2) exp(−Z ² )}/1+cos {(π/2)exp(Z ² )}e
xp(−Tr/T ₁ )dZ...(3) Since the integral of equation (3) is a function of only (T ₁ /Tr), this value is written as Codd(T ₁ /Tr).

(d) Since Codd is a function only of T ₁ /Tr, Codd can be found by numerical integration within the necessary range of T ₁ /Tr, and from this value Codd can be found as a polynomial of T ₁ /Tr.

From the above, the signal strength equation Fs (Tr, Ts, T ₁ , T ₂ , ρ) including the influence of slice shape is Fn
and Codd, a coefficient representing the influence of slice shape.
It is found as the product of

Fs(Tr, Ts, T ₁ , T ₂ , ρ) = Fn(Tr, Ts, T ₁
, T ₂ , ρ) COdd (T ₁ /Tr) where Codd is, for example, 0.2<T ₁ /Tr<
In the case of 10.0, Codd=8.1537E−6(T ₁ /Tr) ⁶ −2.95086E−4(T ₁ /Tr) ⁵ +4.27675E−3(T ₁ /Tr) ⁴ −3.17902E−2(T ₁ /Tr) ³ +1.29262E-1 (T ₁ /Tr) ² -2.8554E-1 (T ₁ /Tr) +1.0557 Pulse sequence consists of one 90° pulse and an even number of 180° pulses In this case, if the signal strength formula that does not include the influence of the slice shape is Fn, the signal strength when the angle at which the magnetization falls is α° is sind/1−cosα・exp(−Tr/T ₁ )・Fn...(4), which can be calculated in the same way as in the above case.

For example, if a Gaussian 90° pulse is used, 0.2<T ₁ /T ₂ <10.0, and the coefficient Ceven representing the influence of slice shape is Ceven = −2.4203E−(T ₁ /Tr) ⁵ +5.6861E−4 (T ₁ /Tr) ⁴ −3.6523E−3 (T ₁ /Tr) ³ −1.0071E−2 (T ₁ /Tr) ² +3.2162E−1 (T ₁ /Tr) +0.9178.

The above is a calculation using a Gaussian 90° pulse, but even if other 90° pulses are used, if the angle α at which the magnetization falls due to the 90° pulse at a point at a distance Z from the center of the slice is found, the same calculation can be performed. Can calculate.

The signal strength formula for the FR4SE method is Io = [1-exp{-(Tr-Ts ₁ -3Ts ₂ -Ts ₃ )/T ₁ }]
ρ/[1−exp{−Tr−Ts, −3Ts ₂ −Ts ₃ )/T ₁ −(Ts ₁ +3Ts ₂ +Ts ₃ )/T ₂ }], the first echo is Io・exp(−Ts ₁ /T ₂ ) The second echo is Io・exp(−Ts ₁ /T ₂ −Ts ₂ /T ₂ ) The third echo is Io・exp(−Ts ₁ /T ₂ −2Ts ₂ /T ₂ ) The fourth The echo is Io·exp(−Ts ₁ /T ₂ −2Ts ₂ /T ₂ ).

(3) Optimization of scan parameters The scan parameters that provide the best evaluation functions for T ₁ , T ₂ , and ρ calculated images of the human body are calculated using the law of error propagation. The signal strength formula (2) above is used as the signal strength formula.

Here, the theoretical formula for signal strength and the required T ₁ ,
A method for determining scan parameters that optimize the evaluation function of a calculated image from T ₂ and ρ values will be explained. Here, the sum of standard deviations normalized as an evaluation function, that is, σ _T1 /T ₁ +σ _T2 /T ₂ +σ〓/ρ, where σ _T1 , σ _T2 , σ〓 are the standard of T ₁ , T ₂ , ρ Use deviation.

The scan parameters of the seven images are 〓 ₁ , 〓
₂ , ..., 〓 ₇ , If the signal strength formula is F ₁ , F ₂ , ..., F ₇ , then T ₁ calculated from the image by the least squares method,
The covariance matrix V _T1T2 〓 of the values of T ₂ and ρ is V _T1T2 〓 = (A ^T V ^-1 ₁₂₃ A) ^-1 However, V ₁₂₃ is the covariance matrix of the original image, and the variance σ ₂ of the original image is It is expressed as σ ² ∝n ^-1 Ta ^-1 , where n is the average value and Ta is the sampling time, and A is becomes.

Therefore, the variance of the values of T ₁ , T ₂ , and ρ is
It is found as the diagonal element of V _T1T2 〓.

From the above, the evaluation functions of the calculated image are 〓 ₁ , 〓 ₂ ,
...= ₇ , Ta ₁ , Ta ₂ , ..., Ta ₇ , n ₁ , n ₂ , ..., n ₇ is found as a function.

Based on this principle, appropriate scan parameters are determined by the following procedure.

Define the theoretical formula for signal strength.

Based on the theoretical formula, the range of T ₁ , T ₂ , and ρ to be measured, and the variance of the original image, the evaluation function of the calculated image is determined as a function of the scan parameter.

In the above, since the evaluation function of the calculated image has been determined as a multivariable function of the scan parameters, the scan parameters that give the best evaluation function are determined by a method (such as the simplex method) that finds the extreme values of the multivariable function.

An example of the scan parameters obtained in this manner is as follows.

When scanning with a total scan time of 600 seconds, in the IR3SE method, Tr = 2.1 seconds Td = 0.457 seconds Ts ₁ = 0.02 seconds Ts ₂ = 0.02 seconds Average number of times (AVE) = 1 In the FR4SE method, Tr = 1.3 seconds Ts ₁ = 0.02 seconds Ts ₂ = 0.073 seconds Ts ₃ = 0.02 seconds Average number of scans (AVE) = 2 When the total scan time is 300 seconds In the IR3SE method, Tr = 1.28 seconds Td = 0.366 seconds Ts ₁ = 0.02 seconds Ts ₂ = 0.02 seconds Average number of times (AVE) = 1 In the FR4SE method, Tr = 1.1 seconds Ts ₁ = 0.02 seconds Ts ₂ = 0.073 seconds Ts ₃ = 0.02 seconds Average number of times (AVE) = 2 (4) Imaging is performed using the scan parameters in (3) above.

That is, in the IR3SE method, scanning is performed using the above parameters over different predetermined views (the number of views is, for example, 127) of a word processing gradient (gradient magnetic field G _y ), and an echo signal is measured.
The measured echo signals are collected in the first, second and third echo signals.
The echo signals are divided into groups, and two-dimensional images are reconstructed using the computer 11 to obtain three original images.

Next, in the FR4SE method, the word processor gradient (gradient magnetic field G _y ) is scanned over different predetermined views (the number of views is, for example, 127) using the above parameters, and echo signals are similarly measured and stored in the waveform memory 21. . The obtained data is divided into first, second, third and fourth echo signal groups and similarly reconstructed into two-dimensional images using the computer 11 to obtain four original images.

(5) Using the seven original images known in (4) above, obtain T ₁ , T ₂ , and ρ images (planned images) by the nonlinear least squares method. (Determined by calculation on the computer 11).

In the above method, the gradient magnetic fields G _x , G _y , G _z and
Slice, projection, and word processing functions are arbitrary.

By the above procedure, calculation images of T ₁ , T ₂ , and ρ can be obtained accurately and simultaneously.

(Other Examples) Note that the present invention is not limited to the above embodiments, but can be implemented as follows.

(1) As a pulse sequence, in the example, the interval from the 90° pulse to the first echo signal is Ts ₁ ,
The interval between each echo signal after the first echo signal is Ts ₂
However, this is defined as the interval from the 90° pulse to the first echo signal, and
The interval from the first echo signal to the second echo signal is Ts ₁ , the interval from the second echo signal to the third echo signal, and the interval from the third echo signal to the fourth echo signal.
The interval to the echo signal is Ts ₂ , the interval from the (2n-2)th echo signal to the (2n-1)th echo signal, and the interval from the (2n-1)th echo signal to the 2nth echo signal ( However, n≧
Let 3) be _Tso . In the case of days, it can be removed by echo.

Furthermore, the interval between each echo signal may be completely arbitrary.

(2) 90° pulse with Gaussian modulation, composite
The 180° pulse is not limited to the embodiment, and other 90° pulses and 180° pulses may be used, and calculated images can be obtained in the same way.

(3) In the example, seven images were obtained from imaging using the IR3SE method and the FR4SE method, and based on these, T ₁ , T ₂ ,
Although we have shown the case where each calculation image of ρ is obtained, without being limited to this, in general, (n+m) images are obtained from imaging using the IRnSE method and the RmSE method, and based on this, T ₁ , T ₂ , Each calculation image of ρ may be obtained.

(Effects of the Invention) As explained above, the present invention has the following effects.

Since no approximation formula is used, accurate values can be obtained.

By using scan parameters that minimize the variance of the counted images, the best calculated image is determined for a given imaging time.

By setting the number of 180° pulses in the IRnSE method to an even number, the standard deviation of the calculated image can be reduced. FIG. 4 shows the sum of normalized standard deviations at representative points of T ₁ values of the human body for various pulse sequence combinations.

As is clear from this graph, when the 180° intensity formula number of the IRnSE method (n is an integer) is the number of corners, the standard deviation is small. i.e. IR4SE
It turns out that it is better to use the IR3SE method than the IR3SE method.

By using the FR method, the standard deviation can be made smaller than other methods. In Figure 4, the IR3SE method and FR4SE method are the best.

In addition, by using the FR method, T ₁ , T ₂ ,
The dispersion can be reduced over a wide range of .

180° ₍₂₎ pulse with composite pulse 90° _-45
By using 270° ₄₅ and 90° _-45 and setting the interval between each echo signal so that two adjacent echo signals are equal, a 100° pulse error can be removed with an even number of echo signals.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the main part of an embodiment of the NMR imaging device according to the present invention, Fig. 2 is a diagram showing a pulse sequence of the IR3SE method, Fig. 3 is a diagram showing a pulse sequence of the FR4SE method, and Fig. 4 is a diagram showing a pulse sequence of the FR4SE method. The figure shows the sum of normalized standard deviations at representative points of the human body's T ₁ and T ₂ values for various pulse sequence combinations;
FIGS. 5 to 7 are diagrams showing examples of conventional pulse sequences. DESCRIPTION OF SYMBOLS 1... Magnet assembly, 2... Main magnetic field coil, 3... Gradient magnetic field coil, 4... RF transmitting coil, 5... Receiving coil, 11... Computer, 12... Display, 13... Controller ,1
4... Gradient magnetic field control circuit, 15... Static magnetic field control circuit, 16... High frequency oscillator, 17... Gate modulation circuit, 18... Power amplifier, 19... Preamplifier, 20... Phase detection circuit, 21... Waveform memory, 30...operation console.

Claims (1)

[Scope of Claims] 1. A nuclear magnetic resonance imaging apparatus that applies high-frequency pulses and a magnetic field to an object to generate nuclear magnetic resonance signals, and uses these signals to obtain an image of the tissue of the object, comprising the following steps: Time (T ₁ , T ₂ ) or proton density (ρ)
1. A nuclear magnetic resonance imaging apparatus characterized by comprising a control/calculation means having the following functions (a) to (c) for obtaining a calculated image regarding at least one of the following: Note (a) IRnSE method (n is an integer) that provides the best evaluation function for T ₁ , T ₂ , and ρ calculation images in the range of interest.
The scan parameters of the FRmSE method (m is an integer) are determined by the following procedure. Define the theoretical formula for signal strength. Based on the theoretical formula, the range of T ₁ , T ₂ , and ρ to be measured and the variance of the original image, the evaluation function of the calculated image is determined as a multivariable function of the scan parameter. Using a method for finding the extrema of a multivariate function, scan parameters are found for which the evaluation function obtained in the above process is the best. (b) Imaging is performed using the scan parameters determined in (b) above using a pulse sequence using the IRnSE method and the FRmSE method. (c) Calculate T ₁ , T ₂ , and ρ images from (n+m) images obtained from imaging using the IRnSE method and the FRmSE method. 2. The nuclear magnetic resonance imaging apparatus according to claim 1, wherein the control/calculation means is configured to apply a 180° pulse an even number of times in a pulse sequence in the IRnSE method. 3 The control/calculation means uses the IR3SE method and the FR4SE method.
2. The nuclear magnetic resonance imaging apparatus according to claim 1, wherein the nuclear magnetic resonance imaging apparatus is configured to perform imaging using a method to obtain seven images, and calculate T ₁ , T ₂ , and ρ images from these seven images. 4 The control/calculation means uses the IR3SE method and the FR4SE method.
According to claim 1, the system is configured such that seven images are obtained by imaging according to the method, and T ₁ , T ₂ , and ρ images are calculated from these seven images, and the following values are used as scan parameters. The nuclear magnetic resonance imaging device described. Note: In the IR3SE method, the time T _r from the first 180° pulse application to the next 180° pulse application is 2.1 seconds, and the time T _d from the first 180° pulse application to the next 90° pulse application is 0.46 seconds. seconds, the time T _s1 from the application of the 90° pulse to the center of the first echo signal generated thereafter is 0.02
seconds, the time from the center of the first echo signal to the center of the second echo signal, and from the center of the second echo signal to the center of the third echo signal, respectively.
Scan a predetermined number of views with T _s2 set to 0.02 seconds. In the FR4SE method, the time T _r from the first 90° pulse application to the first 90° pulse application of the next view is 1.3 seconds, and the time T r from the first 90° pulse application to the center of the first echo signal generated thereafter is 1.3 seconds. time T _s1
0.02 seconds, the time T _s2 from the center of the first echo signal to the center of the second echo signal is 0.073 seconds, and the time T _s3 from the center of the last echo signal to the application of the second 90° pulse is 0.02 seconds. Scan the number of views. The seven images to be obtained are obtained by averaging the IR3SE method and the FR4SE method at a ratio of 1:2. 5 The control/calculation means uses the IR3SE method and the FR4SE method.
According to claim 1, the system is configured such that seven images are obtained by imaging according to the method, and T ₁ , T ₂ , and ρ images are calculated from these seven images, and the following values are used as scan parameters. The nuclear magnetic resonance imaging device described. Note: In the IR3SE method, the time T _r from the first 180° pulse application to the next 180° pulse application is 1.28 seconds, and the time T _d from the first 180° pulse application to the next 90° pulse application is 0.37 seconds. seconds, the time T _s1 from the application of the 90° pulse to the center of the first echo signal generated thereafter is 0.02
seconds, the time from the center of the first echo signal to the center of the second echo signal, and from the center of the second echo signal to the center of the third echo signal, respectively.
Scan a predetermined number of views with T _s2 set to 0.02 seconds. In the FR4SE method, the time T _r from the first 90° pulse application to the first 90° pulse application of the next view is 1.1 seconds, and the time T r from the first 90° pulse application to the center of the first echo signal generated thereafter is 1.1 seconds. time T _s1
0.02 seconds, the time T _s2 from the center of the first echo signal to the center of the second echo signal is 0.073 seconds, and the time T _s3 from the center of the last echo signal to the application of the second 90° pulse is 0.02 seconds. Scan the number of views. The seven images to be obtained are obtained by averaging the IR3SE method and the FR4SE method in a 1:1 ratio.