KR101133977B1 - Water and fat separated magnetic resonance imaging method and apparatus - Google Patents

Abstract

There is provided a water and fat separation magnetic resonance imaging method and apparatus for separating a water image and a fat image through a phase-size coupling density function and repetitive non-uniform magnetic field correction. An RF pulse is applied to an object to be inspected to obtain multi-slice images in which the phases of water and fat of the object are in phase (0 °) and opposite phases (180 °). The phase-size combining density function is calculated by combining magnitude information obtained by taking absolute values of the in-phase multi-slice images and phase information obtained from the multi-slice images of the opposite phase. After setting a point having a maximum frequency from the phase-size combining density function as a starting point, a range of a phase and a size of a water or a lipid component is determined based on the set starting point based on the local growth method. The method comprising the steps of: searching for an image region corresponding to the determined phase and size range, developing phase information in the image region by spherical harmonics, analyzing a pattern of a non-uniform magnetic field, The value is corrected to obtain a water or fat image.

Description

[0001] The present invention relates to a water and fat separation magnetic resonance imaging method and apparatus,

The present invention relates to a magnetic resonance imaging technique for acquiring an image of a water component or a fat component of a human tissue. More particularly, the present invention relates to a magnetic resonance imaging technique for obtaining images of a water component and a fat component of a human tissue, And more particularly, to a method and apparatus for obtaining images of a water component or a fat component that are robust against distortion due to a magnetic field.

The fat-suppression technique in MRI is one of the most useful imaging techniques for observing the cartilage in the cuff, knee, and shoulder joints. There are three types of fat clearing methods. First, the spectral selectivity (spectrally selective) RF pulse or spectroscopy - A method for selectively erasing the fat by using the RF pulse, such as a space-selective (spetral-spatial selective) RF pulse, and second, T _1, and the water and fat signals Short TI recovery (STIR) method with different T ₂ relaxation time, and Dixon method using water and fat phase difference.

Among the above-mentioned fat erasing methods, a method using RF pulses is a method widely used in a high-field magnetic resonance imaging apparatus in which the difference in the car wash frequency between fat and water is large, and the frequency of the applied RF pulse is selectively To obtain an image. This method has the advantage of high signal - to - noise ratio (SNR) as compared with the STIR imaging method, but it is difficult to apply it to the magnetic resonance imaging apparatus of low magnetic field in which the car wash frequencies of the hydrogen and water hydrogen are not significantly different.

The STIR technique detects the video signal when the fat signal reaches zero (the point where the water signal is not zero) after applying the reversal pulse using the difference between the T ₁ and T ₂ relaxation times of the fat and water signals. This technique has the advantage of robustness against the nonuniformity of the magnetic field, but has a disadvantage in that the spatial resolution is reduced due to a low signal-to-noise ratio.

The Dixon technique uses a different frequency of the hydrogen and water of the hydrogen and water to obtain the image when the phase of water and fat is the same when the phase of water and the fat is reversed, You can get your own image. This technique has an advantage that it can be used in authors' magnetic resonance imaging apparatuses in which the car wash frequencies of fat and water are not significantly different from each other, but it is disadvantageous in that it is highly influenced by the unevenness of the magnetic field.

SUMMARY OF THE INVENTION The present invention provides a method and apparatus for separating a water image and a fat image through a phase-size coupling density function and a repetitive non-uniform magnetic field correction. It has its purpose.

In order to achieve the above object, a water and fat separation MRI method according to the present invention comprises the steps of (i) applying an RF pulse to an object to be examined to determine whether the phase of water and fat of the object is in phase (0 °) ≪ RTI ID = 0.0 > °) < / RTI > (ii) calculating a phase-size combining density function by combining magnitude information obtained by taking absolute values of the in-phase multi-slice images and phase information obtained from the multi-slice images of the opposite phase; (iii) determining a range of phase and size of a water or fat component in a local growth mode based on the set start point after setting a point having a maximum frequency from the phase-size binding density function as a start point; And (iv) analyzing a non-uniform magnetic field pattern by searching an image region corresponding to the determined phase and size range and developing phase information in the image region using spherical harmonics, And obtaining a water or fat image by correcting the uneven magnetic field value of the water or fat image.

The water and fat separating MRI apparatus according to the present invention is provided with a space in which a subject to be inspected can be placed and has a gradient magnetic field in the direction of magnets, x-axis, y-axis and z- An array RF coil for exciting an RF pulse to the object and receiving a magnetic resonance signal generated from the object; An inclination amplifier for causing the oblique magnetic field coil to generate a gradient magnetic field by supplying a current to the gradient magnetic field coil; An RF amplifier for amplifying the modulated RF input and applying the amplified RF input to the array RF coil to excite the object; A controller for applying a gradient magnetic field input to the gradient amplifier or applying a modulated RF input to the RF amplifier according to a user-selected imaging technique sequence; A receiver for receiving and demodulating the magnetic resonance signal from the array RF coil; An analog / digital converter for converting the demodulated magnetic resonance signal into a digital signal and outputting the digital signal; And obtaining multi-slice images in which phases of water and fat of the object are in phase (0 °) and opposite phases (180 °) based on the digital MRI signal from the analog-to-digital converter, Size combining density function by combining the size information obtained by taking the absolute values of the phase-size combining density function and the phase information obtained from the reversed-phase multi-slice images, and calculating a phase- Determines a range of a phase and a size of a water or a fat component by a local growth method on the basis of the set start point, searches an image region corresponding to the determined phase and size range, And the pattern of the non-uniform magnetic field is analyzed, and as the pattern value of the non-uniform magnetic field To correct the value of the magnetic field non-uniformity in a pixel is characterized in that it comprises a computer to obtain a water or fat images.

The present invention relates to a water and fat separation magnetic resonance imaging method and apparatus for selectively obtaining water or fat images of a human tissue by self-correcting magnetic field irregularity in a low magnetic field magnetic resonance imaging apparatus. The present invention can be used for diagnosis by avoiding masking of a weak signal tissue at a site adjacent to water and fat by a strong signal around it through a phase-size binding density function and repetitive non-uniform magnetic field correction. It is also possible to apply the non-uniform magnetic field correction method repeatedly to improve performance, to improve the performance by repeatedly updating the phase-size coupling density function, to improve the performance by repeatedly updating the water or fat region, Can be simultaneously applied to a three-dimensional multi-slice.

1 is a block diagram showing the configuration of a water and fat separation MRI apparatus according to an embodiment of the present invention.
2 is a flowchart illustrating a water and fat separation MRI method according to an embodiment of the present invention.
3 is a diagram illustrating a gradient magnetic field echo-based pulse sequence that may be used in the present invention.
Figure 4 is a diagram illustrating a spin echo based pulse sequence that may be used in the present invention.
5 is a diagram illustrating a phase distribution of Q 'in a subject region according to an embodiment of the present invention.
6 is a conceptual diagram of distribution of water and fat signals of JPMF showing water and fat distribution according to an embodiment of the present invention.
FIG. 7 is a view showing an inphase image experimentally obtained from a phantom composed of water and oil according to an embodiment of the present invention.
8 is a view showing a JPMF for an experimental image according to an embodiment of the present invention.
Fig. 9 is a view showing a range (expressed in white) of water components obtained from JPMF in Fig. 8; Fig.
Fig. 10 is a view showing a water region (indicated by white for one slice image) obtained from the water component range of Fig. 9. Fig.
11 is a view showing an in-phase image of a knee joint region according to an embodiment of the present invention.
12 is a view showing an image of a water component that has not been subjected to the non-uniform magnetic field correction according to the embodiment of the present invention.
13 is a view showing an image of a fat component which is not corrected for a non-uniform magnetic field according to an embodiment of the present invention.
FIG. 14 is a view showing an image of a water component obtained by correcting a non-uniform magnetic field once according to an embodiment of the present invention.
FIG. 15 is a diagram showing an image of a fat component obtained by correcting a non-uniform magnetic field once according to an embodiment of the present invention.
16 is a view showing a water component image obtained by correcting the non-uniform magnetic field three times according to the embodiment of the present invention.
17 is a view showing an image of a fat component obtained by correcting a non-uniform magnetic field three times according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a water and fat separation magnetic resonance imaging apparatus and method robust to non-uniformity of a magnetic field according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram showing the configuration of a water and fat separation MRI apparatus according to an embodiment of the present invention.

The water and fat separation MRI apparatus according to an embodiment of the present invention includes a magnet assembly 101, an gradient amplifier 105, an RF amplifier 106, a controller 110, a receiver 108, an analog-to-digital converter 109 ), A computer 111, and an operation console 112.

The magnet assembly 101 includes a magnet 104 for providing a space in which an object to be inspected can be placed and applying a constant main magnetic field, a gradient magnetic field generating unit 107 for generating an inclined magnetic field in the x-axis, y- A coil 102, and an array RF coil 103 for exciting an RF pulse to the object and receiving a magnetic resonance signal generated from the object.

The slope amplifier 105 supplies the slope magnetic field coil 102 with a current to cause the slope magnetic field coil 102 to generate a gradient magnetic field. The RF amplifier 106 amplifies the modulated RF input and applies it to the array RF coil 103 via a coupler 107, which is a Tx-Rx switch, to excite the object.

The control unit 110 applies a gradient magnetic field input to the gradient amplifier 105 or a modulated RF input to the RF amplifier 106 according to a video technique sequence selected by the user. The receiver 108 receives and demodulates the magnetic resonance signal from the array RF coil 103.

The MR signal received from the multichannel array RF coil 103 is input to the receiver 108 through the coupler 107 and demodulated and then converted into a digital signal by the A / Lt; / RTI >

Based on the digital magnetic resonance signal from the analog-to-digital converter 109, the computer 111 generates multi-slice images in which the phases of water and fat of the object are in phase (0 °) and opposite phases (180 °) . The computer 111 calculates the phase-size combining density function by combining the magnitude information obtained by taking absolute values of the in-phase multi-slice images and the phase information obtained from the multi-slice images of the opposite phase.

The computer 111 sets a point having a maximum frequency from the phase-size combining density function as a starting point, and then determines a range of a phase and a size of a water or a lipid component by a local growth method based on the set starting point. The computer 111 searches for an image region corresponding to the determined phase and size range, analyzes the non-uniform magnetic field pattern by developing the phase information in the image region in spherical harmonics, To obtain a water or fat image. The computer 111 transmits information for obtaining the magnetic resonance signal to the control unit and operates the control unit 112. The control unit 111 receives a command of the user through communication with the operation console 112 or displays a resultant image Output.

The processing procedure of the present invention can be described as shown in Fig. In order to receive the MR signal for the present invention, the MR signal can be obtained using the pulse sequence shown in FIG. 3 or FIG. Figure 3 is a sequence based on gradient magnetic field echoes, and Figure 4 is a sequence based on spin echoes.

3, reference numeral 300 denotes a sequence for obtaining an MR signal having the same phase of a water component and a lip component based on a gradient magnetic field echo, 310 denotes a MR This is a sequence for obtaining a signal.

Referring to FIG. 3, the RF pulse 301 is used to select a two-dimensional image section and serves to determine and excite a sagging angle of a hydrogen atom present in a cross section selected by a slice selection gradient 302. A phase encoding gradient 304 and a frequency encoding gradient 305 and 306 are added to the previously calculated two dimensional image information to obtain a two dimensional image information. MR signal 307 is obtained. Then, a spoiler 303 is applied to each axis for the next sequence to disperse the remaining magnetized components.

In order to make the phase of the water component and the lip component of the MR signal 307 equal to each other in the pulse sequence 300 described above, the echo time (TE, echo time), which is the time between the RF pulse 301 and the MR signal 307, It should be set appropriately. Since the water component and the fat component usually have a frequency difference of about 3.5 ppm, when the main magnetic field intensity of the embodiment of the present invention is 0.35 tesla, the frequency difference between water and fat component is about 52 Hz. Through this frequency difference, the echo time (TE1) for the water and fat components to become the same phase becomes about 19 ms. And the echo time for the water and fat components to be in opposite phases is 9.5 ms, which is half of 19 ms. The pulse sequence 310 obtains the MR signal whose phase of the water and the fat signal is 180 DEG by setting the echo time TE2 to 9.5 ms. ΔT represents the time difference between TE1 and TE2.

4 is a pulse sequence for obtaining an MR signal having the same phase of water and fat components based on spin echo, 410 is a pulse for obtaining an MR signal having a 180 ° phase difference between water and fat components based on a spin echo, Sequence.

In order to obtain an MR signal having the same or opposite phase of water and lipid components in the pulse sequence of FIG. 4, the point of time of the refocusing RF pulse 401 and the section selection gradient magnetic field 402 should be adjusted. If the refocused RF pulse 401 is located in the middle of the RF pulse 301 and the MR signal 307, the phases of the water and fat component signals are the same. In order to make the phase difference between the water and fat component signals 180 degrees, the positions of the refocusing RF pulse 401 and the section selection gradient magnetic field 402, such as 410 pulse sequences, And then the MR signal 307 is obtained at the same time.

As shown in FIG. 3 or FIG. 4, the signal of water and lipid component is generated by using a pulse sequence that can obtain an MR signal having a phase difference of 180 ° between water and fat component signals, And multi-slice images having a reverse phase (OUT-OF-PHASE) are obtained (step 201).

The in-phase and inverse-phase images obtained in step 201 are Fourier-transformed to reconstruct the in-phase and inverse-phase images (step 202). At this time, the characteristics of the in-phase image I and the reversed-phase image Q can be expressed by the following equations (1) and (2).

The above equation represents a common e ^iφ0 phase occurring in the image in-phase and reverse phase delay or the like by the filter characteristics, each array element of the coil characteristics RF- coil (103) of the system, e ^iφ is during the delay time (ΔT) Represents the phase caused by the non-uniformity of the main magnetic field. In the present invention, Equation (1) is defined as an in-phase image and Equation (2) is defined as a reversed-phase image, W denotes a water component signal, and F denotes a fat component signal.

When the reconstructed image of the z-position slice measured by the n-th element coil is _denoted by I ⁿ _z and Q ⁿ _z , the channel data after the phase correction is summed to obtain the size information and phase information of the improved signal- (Steps 203 and 204). The size information and the phase information of the image can be expressed by the following equations (3) and (4).

Equations (3) and (4) are for eliminating the phase (e ^iφ0 ) occurring in the system in Equations (1) and (2) and ultimately, by the method of the present invention, the phase e ^-i To obtain images of water (W) or fat (F) components.

In order to separate water and fat using the characteristics of the MR image of the in-phase and the reverse-phase, a phase-size combining density function (JPMF, Joint Phase-Magnitude Density Function) (Step 205).

JPMF represents the joint distribution in two-dimensional space using I ^' _z and ∠Q ^' _z in Equations (3) and (4). That is, JPMF is given by the following equation (5).

Where histo denotes the histogram, u and v denote the parameters of the phase-size coupling density function, and Δp and Δm denote the phase and magnitude intervals.

The histogram is obtained for all slices (three-dimensional volume) of the image. By doing so, the histogram can be robust to changes in the presence or absence of water and fat components in each slice, and the same image quality can be expected for all slices.

Since the change in the image size due to the non-uniform magnetic field is significantly smaller than the change in the phase, the classification of water and fat using the coupling density function of the phase and magnitude proposed in the present invention is advantageous in that the non- .

The distribution of the water and fat Q ^'phase of _z ^(∠Q' of the equation (4) from the object to which _z) is illustrated in FIG. As shown in FIG. 5, it can be seen that the phase distribution is not concentrated at 0 ° and 180 ° depending on the components of water and fat but spread by non-uniformity. In this case, it is not possible to divide the range of water and fat by only the phase distribution. However, in the present invention, water and fat can be separated into two dimensions as shown in FIG. 6 by the combined density function of phase and size. In the present invention, the magnitude difference between water and fat signals can be easily changed by an experiment variable such as TR (Repetition Time) in a magnetic resonance image, and it is utilized to distinguish water and fat using phase information and size information.

To find the range of water and fat using JPMF, the distribution of water and fat should be clustered in JPMF. In the present invention, the point having the maximum frequency in the two-dimensional density function of the JPMF is set as a starting point, and then the range of the water or the fat component is grouped by the regional growth method on the basis of this point, ). The maximum frequency point is assumed to represent the size and phase of each component.

The range of water (R _W ) and the range of fat (R _F ) thus obtained are conceptually shown in FIG. If the location of the pixels having the phase and the size corresponding to the range of water R _W defined in JPMF is found in all the slices, the region A _w of the water component can be extracted (step 207). That is, the area A _W of the water component is given by the following equation (6).

An image obtained experimentally from a phantom composed of water and oil is shown in FIGS. 7 to 10. FIG. 7 is a cross-sectional view of a size image (in-phase image) obtained by multi-slice. The lower part of Fig. 7 is water, and the upper part is oil. 8 is JPMF obtained from the experimental image. In Fig. 8, the red color represents a high frequency. Figure 9 shows the result of plotting the range of water from JPMF. In Fig. 9, the portion indicated by white is the range of water. FIG. 10 shows a region corresponding to the range of water shown in FIG. In Fig. 10, the area indicated in white is the selected water area.

Dimensional nonuniformity pattern of the magnetic field by using three-dimensional spherical harmonics as shown in Equation (7) using the phase information corresponding to the region of the water component.

In Equation (7), x and y represent coordinates in each slice image, and z represents a slice at z position. The spherical harmonics are considered up to the second order, and the coefficients of each pattern are obtained by pseudo - inverse calculation.

The non-uniform magnetic field pattern obtained by the expression (7) in the water component region is expanded to the entire image region. This is based on the property that the non-uniform magnetic field is in principle not related to the image and does not change rapidly. If the phase term corresponding to the non-uniform magnetic field expanded for the entire image area is removed in units of pixels in the phase of the reversed image of Equation (4), the non-uniform magnetic field is corrected as shown in Equation 8 (Step 208).

The phase can be corrected by repeating steps 205 to 208 using the phase-corrected reversed-phase image (Q _{z &} ^quot; ) and the magnitude image of equation (3) (step 209).

When the phase due to the non-uniform magnetic field is corrected, Q ^" has a real value, and water and a lipid image can be obtained using Equations (9) and (10) (Step 210).

In Equations (9) and (10), Real represents a real part of Q ^" having a complex value.

11 to 17 show a result image obtained when the non-uniform magnetic field proposed in the present invention is repeatedly corrected (209). Fig. 11 shows a size image of the in-phase image, and Figs. 12 and 13 show images of water and fat components obtained when the non-uniform magnetic field is not corrected. Figs. 14 and 15 are images of water and fat components obtained after correcting the first nonuniform magnetic field. Fig. 16 and 17 are images of water and fat components obtained after three repetitions of correction. It can be seen from Figs. 16 and 17 that water and oil images are remarkably improved when compared with Figs. 12 and 13 in which the non-uniform magnetic field is not corrected. Compared with Figs. 14 and 15, it can be seen that distortion is reduced when the non-uniform magnetic field is repeatedly corrected.

As can be seen from the resultant image, according to the present invention, by correcting the non-uniform magnetic field of the main magnetic field, it was possible to obtain images of only selected components with remarkably reduced distortion and to obtain good results which are helpful for diagnosis.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken in conjunction with the present invention. Anyone with a variety of variations would be possible.

The water and fat separation magnetic resonance imaging method and apparatus according to the present invention can be applied to separation of water and fat images in vivo using magnetic resonance.

101: Magnetic assembly 102: Oblique magnetic field coil
103: array RF coil 104: magnet
105: slope amplifier 106: RF amplifier
107: coupler 108: receiver
109: A / D converter 110:
111: Computer 112: Operation console

Claims (8)

(i) applying a RF pulse to an object to be inspected to obtain multi-slice images in which phases of water and fat of the object are in phase (0 °) and opposite phases (180 °);
(ii) calculating a phase-size combining density function by combining magnitude information obtained by taking absolute values of the in-phase multi-slice images and phase information obtained from the multi-slice images of the opposite phase;
(iii) determining a range of phase and size of a water or fat component in a local growth mode based on the set start point after setting a point having a maximum frequency from the phase-size binding density function as a start point; And
(iv) searching an image region corresponding to the phase and size range of the determined water or fat component, developing the phase information in the image region by spherical harmonics, analyzing a pattern of a non-uniform magnetic field, And applying the same to the multi-slice images to obtain a water or fat image by correcting non-uniform magnetic field values. The method of claim 1, wherein step (ii)
(ii-1) to Fourier transform of all in-phase and opposite-phase imaging equation I = (W + F) e ^iφ0 e ^iφ) and (Q = (W - F) statues which are respectively represented by e ^iφ0 image (I) and reversed-phase E ^{i? 0} represents a phase commonly occurring in in-phase and inverse phase images due to system delay, filter characteristics, element coil characteristics of the array RF-coil, etc., and e ^i? Wherein W represents a water component signal and F represents a fat component signal;
(ii-2) When reconstructing the slice image of the z-position measured with the n-th element coil, I ⁿ _z and Q ⁿ _z , the channel data after the phase correction is summed,

And Equation

Obtaining the size information (I ' _z ) and the phase information (Q' _z ) of the enhanced image signal-to-noise ratio, respectively; And
(ii-2) I _^'z and ^∠Q' equation by using the _z showing the joint distribution on the two-dimensional space, _{f PM (u, v) =} histo (u △ p ≤∠Q '<(u + 1) △ p ^{, v △ m≤I '<(v} + 1) △ m) the phase represented by - calculating the size link density function, and the histo represents the histogram, u and v is the phase-variable, the size of the combined density function , &Lt; / RTI &gt; and &lt; RTI ID = 0.0 &gt; m &lt; / RTI &gt; The method of claim 1, wherein step (iii)
(iii-1) a point having a maximum frequency in a two-dimensional density function of a phase-size binding density function is set as a starting point, and then a range of water or a fat component is clustered by a local growth method, R _W ) and a range of fats (R _F ); And
(iii-2) the range defined in the water _(W R) the expression by searching for positions of the pixels having a phase and a size in all slices to the _{A W = {(x, y} , z) | ∠Q 'z ( (A _W ) of water components given as x, y) ∈ R _W , I ^' _z (x, y) ∈ R _W }. 3. The method of claim 2, wherein step (iv)
(iv-1) equation by using the phase information that corresponds to the area of the water component: φ (x, y, z ) = a and z ² + b and ^{(x 2 - y 2) +} c and xy + d A, b, c, d, e, f, g, h, and I represent the phase information and the equation Wherein x and y each represent coordinates in a slice image, and z is a non-uniformity pattern of a magnetic field indicating a slice at a z position; And
(iv-2) expanding the non-uniform magnetic field pattern obtained in the equation (iv-1) in the water component region to the entire image region, and adding a phase term corresponding to the non-

By subtracting, in pixel units, the phase of the reversed-

And performing the correction of the uneven magnetic field as shown in FIG. 2. The method of claim 1, wherein in step (v), when the phase by the non-uniform magnetic field is corrected, Q " has a real value,

And

And Real represents a real part of Q " with a complex value. 2. The method of claim 1, further comprising the step of: (v) obtaining a phase-size binding density function again in the water or fat image and repeating steps (ii) to (iv) Water and fat separation magnetic resonance imaging. A gradient magnetic field coil provided with a space in which an object to be inspected can be placed and generating a gradient magnetic field in the x-, y-, and z-axis directions for applying a constant main magnetic field, an RF pulse applied to the object And an array RF coil for receiving a magnetic resonance signal generated from the object;
An inclination amplifier for causing the oblique magnetic field coil to generate a gradient magnetic field by supplying a current to the gradient magnetic field coil;
An RF amplifier for amplifying the modulated RF input and applying the amplified RF input to the array RF coil to excite the object;
A controller for applying a gradient magnetic field input to the gradient amplifier or applying a modulated RF input to the RF amplifier according to a sequence selected according to a user-selected imaging technique;
A receiver for receiving and demodulating a magnetic resonance signal from the array RF coil;
An analog / digital converter for converting the demodulated magnetic resonance signal into a digital signal and outputting the digital signal; And
Obtains multi-slice images in which phases of water and fat of the object are in phase (0 °) and opposite phases (180 °) based on a magnetic resonance signal converted into a digital signal from the analog-to-digital converter, Calculating a phase-size combining density function by combining magnitude information obtained by taking an absolute value of each of the multi-slice images and phase information obtained from the multi-slice images of the opposite phase, and calculating a phase- Determining a range of a phase and a size of a water or a fat component using a local growth method based on the set starting point after setting a point as a starting point and searching an image region corresponding to the determined phase or size range of the water or fat component The phase information in the image area is expanded by spherical harmonics to analyze a pattern of a non-uniform magnetic field, Non-uniform by applying a pattern of magnetic fields in the multi-slice image to correct for non-uniform magnetic field values that includes a computer to obtain a water or fat images of water and fat separation MR imaging device. The method of claim 7, wherein the computer is the Fourier transform of all the in-phase and opposite-phase image through the signal processing equation I = (W + F) e ^iφ0 e ^iφ) and (Q = - respectively (W F) e ^{iφ0 Phase} image (I) and a reversed-phase image (Q) to be ^expressed , wherein the e ^{iφ 0} is a phase that is commonly generated in the in-phase and inverse phase images due to system delay, filter characteristics, and element coil characteristics of the array RF coil ^Wherein e ^iφ represents a phase caused by non-uniformity of the main magnetic field during a delay time, W represents a water component signal, F represents a fat component signal, and transmits information for obtaining the magnetic resonance signal to the controller And a water and fat separation magnetic resonance imaging apparatus that receives a user's command through communication with the operation console or outputs the resultant image to a user so that the user can measure the resultant image.

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