A nonlinear coded imaging method and system

Abstract

The application relates to a nonlinear encoding imaging method and system, relates to the field of nuclear magnetic resonance, and solves the problem that an image cannot be directly obtained through Fourier transform for image reconstruction under nonlinear encoding. The method comprises the following steps: acquiring a uniform ring-distributed sub-encoding field of coil units around a Z axis, so that the current amplitude of all the coil units is distributed on a sine curve in a period, and a static encoding field is generated through superposition; performing sine modulation on the current amplitude of the coil units, so that the current amplitude of all the coil units changes in the sine period, a dynamic encoding field is generated; a nuclear magnetic resonance signal generated by the dynamic encoding field and excitation is received through a radio frequency receiving array coil group, additional spatial encoding information provided by the sensitivity distribution of the radio frequency receiving array coil group is analyzed, a target image is acquired, and reconstruction is performed. The application has the following effects: when the encoding field is a nonlinear encoding field, the rapid imaging of a nuclear magnetic resonance image can be effectively ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of nuclear magnetic resonance, in particular to a nonlinear encoding imaging method and system. BACKGROUND

[0002] The smallest geometric unit that can be distinguished on a magnetic resonance image is a pixel, which corresponds to the magnetic resonance signal of each voxel in the imaged object. When the nuclear magnetic resonance phenomenon is generated in the imaged object after being excited by a radio frequency magnetic field, the electrical signal released by the magnetic nuclei in the entire imaged object during the relaxation process is received by the receiving coil. Only by obtaining the magnetic resonance signal of each voxel and its spatial position, can each pixel on the image be one-to-one corresponding to each voxel of the anatomical structure of the imaged object, similar to the way we use latitude and longitude to locate any position on the earth. We call the method of giving the spatial position information of the magnetic resonance signal as magnetic resonance signal spatial encoding, and the main method is to use gradient magnetic fields in different directions to encode the signal for subsequent image reconstruction.

[0003] Generally, the spatial encoding of the magnetic resonance signal uses linear and orthogonal X and Y gradients to encode the image, which is an intuitive and convenient way, and then the total signal collected is directly Fourier transformed to obtain the image.

[0004] For the related technologies in the above, the inventors find that there are the following defects: With the expansion of unconventional magnetic resonance systems in the field of MRI applications, the application of the current unconventional magnetic resonance system has been relatively wide. The encoding field applied by the unconventional magnetic resonance system is a nonlinear encoding field, which means that the encoding field is not linearly changed in space. Therefore, for image reconstruction under nonlinear encoding, the image cannot be directly obtained by Fourier transform. SUMMARY

[0005] In order to effectively guarantee the fast imaging of the nuclear magnetic resonance image when the encoding field is a nonlinear encoding field, the present application provides a nonlinear encoding imaging method and system.

[0006] In a first aspect, the present application provides a nonlinear encoding imaging method, which adopts the following technical solution:

[0007] A nonlinear encoding imaging method, comprising:

[0008] Obtaining a sub-encoding field of a coil unit uniformly arranged around the Z axis, so that the current amplitude of all coil units is distributed on a sine curve in one period, and a static encoding field is generated by superposition;

[0009] Performing sine modulation of the current amplitude of the coil unit, so that the current amplitude of all coil units changes in the above sine period, and a dynamic encoding field is generated.

[0010] The dynamic encoding field and the nuclear magnetic resonance signal generated by the excitation thereof are received by the radio frequency receiving array coil set, and additional spatial encoding information provided by the sensitivity distribution of the radio frequency receiving array coil set is analyzed to obtain a target image and reconstruct the same.

[0011] By using the above technical solution, the static encoding field is generated by superimposing the obtained sub-encoding field, and the dynamic encoding field is generated by sinusoidal modulation, so that different spatial position imaging pixels have different encoding information, i.e., the phase information of the signals generated by different position imaging pixels is different, and all signals can be distinguished according to the additional spatial encoding information provided by the dynamic encoding field and the sensitivity distribution of the radio frequency receiving array coil set, thereby laying a foundation for the reconstruction of the target image.

[0012] Optionally, the number of coil units uniformly arranged around the Z-axis is an even number, and the symmetric coil units have the same current magnitude and opposite directions at the same time, and the number of driving sources is half of the number of coil units.

[0013] By using the above technical solution, since the number of coils is an even number and uniformly distributed, the driving current has the same magnitude and opposite directions at the same time, so that the two coil units on the opposite sides are regarded as driving channels, thereby reducing the number of required driving sources by half on the basis of ensuring the formation of the static encoding field, and the overall cost is reduced.

[0014] Optionally, the sub-encoding field of the coil unit uniformly arranged around the Z-axis is obtained, so that the current amplitude of all coil units is distributed on a sinusoidal curve in one period, and the static encoding field is generated by superimposition as follows:

[0015] The static encoding field is independently controlled by the coil unit group uniformly arranged around the Z-axis, and the number of coils contained in the coil unit group is N k , and the specific formation formula of the static encoding field is as follows: Wherein, b i (r) is the sub-encoding field generated by the coil unit i under unit current driving, r is a spatial position variable; I i (t) represents the driving current applied to the corresponding coil unit i at time t; b nl (t,r) is the static encoding field generated by superimposition;

[0016] Wherein, at time t0, the amplitude of the driving current applied to the corresponding coil unit i is subject to sinusoidal distribution, and the specific formula is as follows: I i (t0)=I m sin(2π / N k *i);Wherein, I m represents the maximum current amplitude;

[0017] Obtaining a static encoding field.

[0018] By adopting the technical solution, the sub-encoding field generated by each coil unit under the current drive can be calculated and superimposed one by one, and the static encoding field generated by superposition can be effectively calculated and analyzed.

[0019] Optionally, the sine modulation of the amplitude of the driving current of the coil unit is performed, so that the current amplitude of all coil units changes in the above sine period, and a dynamic encoding field is generated, including:

[0020] When the preset time node is located after the preset first time node and the time difference from the preset first time node is a preset time interval multiple, the driving current initial value of each channel is again given a half-period sine modulation, specifically as follows:

[0021]

[0022] Wherein, q is the non-linear encoding field ordinal number, q=0,1,…,N-1, representing different time points; step depends on the total number of encoding field changes N: step=2π / N;

[0023] Obtaining a dynamic encoding field.

[0024] By adopting the technical solution, the current value of all coils changes, and the change is subject to a sine distribution, so that the original static encoding field is dynamic, forming a dynamic encoding field, so that different spatial position imaging voxels have different encoding information.

[0025] Optionally, a non-linear encoding imaging method further includes a step located after the driving current initial value of each channel is again given a half-period sine modulation and before obtaining a dynamic encoding field, specifically as follows:

[0026] The driving current initial value of each channel is given a sine modulation of the following period, specifically as follows:

[0027] Wherein, Ns is the total number of sampling points.

[0028] By adopting the technical solution, the dynamic encoding field is further modulated and changed on the original basis, so that the number of times of consecutive sine curves of the possible distribution of the current amplitude is reduced, the original multiple sine modulation is reduced, the efficiency of obtaining the phase information of the signal generated by all position imaging voxels is improved, and the imaging efficiency is improved.

[0029] Optionally, analyzing and obtaining a target image and reconstructing include:

[0030] The additional spatial encoding information and the nuclear magnetic resonance signal provided by the sensitivity distribution of each radio frequency receiving coil unit are obtained; based on the relationship followed by the nuclear magnetic resonance signal, the target image is obtained by reverse analysis and reconstructed.

[0031] By adopting the above technical solution, all signals can be distinguished by effectively utilizing spatial coding information and the different phase information of signals generated by imaging voxels at different positions, laying the foundation for the reconstruction of the target image.

[0032] Optionally, the NMR signal follows the following relationship:

[0033]

[0034] Among them, s j (q) is the signal collected by the jth RF receiving channel in the entire imaging space V, m(r) is the target image, c j (r) is the sensitivity distribution of the j-th RF receiving coil unit; i is a unit imaginary number, and γ is the magnetic gyrometry ratio.

[0035] Optionally, m(r) is solved as follows:

[0036] Will Simplified to s = Em; where E is the encoding matrix, including c j (r) and e index terms; s is the signal matrix; m is the target matrix;

[0037] The preset iterative calculation formula is used to perform inverse analysis to obtain the target matrix.

[0038] Optionally, the preset iterative calculation formula is as follows:

[0039]

[0040] Where n represents the number of iterations, and are the estimated values ​​of the nth and n+1th images m, respectively. is the i-th row of the received signal matrix, is the i-th row of the encoding matrix, λ is the iteration parameter, * represents the complex conjugate, brackets represent inner products, and double bars represent vector norms.

[0041] In a second aspect, the present application provides an image reconstruction system under nonlinear coding, which adopts the following technical solution:

[0042] An image reconstruction system under nonlinear coding, characterized by comprising:

[0043] The acquisition module acquires a sub-encoding field of the coil unit distributed around the Z axis to make the current amplitude of all coil units distributed on a sine curve in a period, and the superposition generates a static encoding field;

[0044] The dynamic encoding field forming module performs sinusoidal modulation of the current amplitude of the coil unit to make the current amplitude of all coil units change in the above-mentioned sine period, and generates a dynamic encoding field;

[0045] The target image reconstruction module receives the dynamic encoding field and the nuclear magnetic resonance signal generated by the excitation of the dynamic encoding field through the radio frequency receiving array coil group, and analyzes and acquires the target image according to the additional spatial encoding information provided by the sensitivity distribution of the radio frequency receiving array coil group, and reconstructs the target image.

[0046] By adopting the above technical solution, the static encoding field is generated by the acquisition module using the acquired sub-encoding field, and the dynamic encoding field is generated by the dynamic encoding field forming module through sinusoidal modulation, so that different spatial position imaging pixels have different encoding information, that is, the phase information of the signals generated by different position imaging pixels is different, and finally, according to the additional spatial encoding information provided by the dynamic encoding field and the sensitivity distribution of the radio frequency receiving array coil group, all signals can be distinguished by the target image reconstruction module, which lays a foundation for the reconstruction of the target image.

[0047] In summary, the beneficial technical effects of the present application are:

[0048] 1. The non-linear encoding imaging method can effectively guarantee the fast imaging of the nuclear magnetic resonance image when the encoding field is a non-linear encoding field.

[0049] 2. The number of driving sources is reduced while realizing fast imaging. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1 FIG. 1 is a schematic diagram of the overall process of a non-linear encoding imaging method according to an embodiment of the present application.

[0051] Figure 2 FIG. 2 is a schematic diagram of the overall process of performing sinusoidal modulation of the current amplitude of the coil unit to make the current amplitude of all coil units change in the above-mentioned sine period, and generate a dynamic encoding field according to another embodiment of the present application.

[0052] Figure 3 FIG. 3 is a spatial distribution diagram of the static encoding field in the embodiment of the present application.

[0053] Figure 4 FIG. 4 is a curve diagram of the current of one channel changing with time in the process of giving the initial value of the driving current of each channel a sinusoidal modulation of half a period according to the embodiment of the present application.

[0054] Figure 5 is a flowchart of another embodiment of the application for acquiring a target image and reconstructing.

[0055] Figure 6 is a system block diagram of a nonlinear encoding imaging system of the application.

[0056] In the figure, 1, acquisition module; 2, dynamic encoding field forming module; 3, target image reconstruction module. DETAILED DESCRIPTION

[0057] The application will be further described in detail below with reference to the accompanying drawings.

[0058] Reference Figure 1 A nonlinear encoding imaging method disclosed by the application comprises:

[0059] Step S100, acquiring a sub-encoding field of coil units uniformly arranged around the Z-axis, so that the current amplitude of all coil units is distributed on a periodic sinusoidal curve, and a static encoding field is superimposed.

[0060] In the coordinate system of MRI, the Z-axis is defined as the direction parallel to the main magnetic field B0, and after the z-axis direction is determined, the x and y axes are orthogonal (perpendicular) to the z-axis; the coil units can be independently driven using a small current, and a spatiotemporal varying sub-encoding field is generated by changing the current of the coil units; the coil units are uniformly arranged around the Z-axis, which means that the angle formed by any adjacent coil units with respect to the Z-axis is the same.

[0061] The number of coils included in the coil unit group uniformly arranged around the Z-axis is an even number, and the driving currents of the symmetric coil units are the same in size and opposite in direction at the same time, and the number of driving sources is half the number of coil units; taking 8 as an example, the angle formed by any adjacent coil units with respect to the Z-axis is 45 degrees, and the number of driving sources is 4.

[0062] Specifically, acquiring a sub-encoding field of coil units uniformly arranged around the Z-axis so that the current amplitude of all coil units is distributed on a periodic sinusoidal curve, and a static encoding field is superimposed comprises the following steps:

[0063] Step S110, independently controlling the coil unit group uniformly arranged around the Z-axis to generate a static encoding field, the number of coils included in the coil unit group is N k The specific formula for forming the static encoding field is as follows:

[0064] Where b i (r) is the sub-encoding field generated by the coil unit i under unit current driving, r is a spatial position variable; I i(t) represents the driving current applied to the corresponding coil unit i at time t; b nl (t, r) is the superimposed generated static encoding field; wherein the amplitude of the driving current applied to the corresponding coil unit i at time t = t0obeys a sinusoidal distribution, specifically as follows: I i (t0) = I m sin(2π / N k *i); wherein I m represents the maximum current amplitude.

[0065] Specifically, after completing the above-mentioned sinusoidal modulation, the generated encoding field b nl (t0, r) has a general spatial distribution as Figure 3 .

[0066] Step S120, obtaining the static encoding field.

[0067] Step S200, performing sinusoidal modulation of the coil unit driving current amplitude, so that the current amplitude of all coil units changes within the above-mentioned sinusoidal period, generating a dynamic encoding field.

[0068] Step S300, receiving the dynamic encoding field and the nuclear magnetic resonance signal generated by its excitation by the radio frequency receiving array coil group, and analyzing and reconstructing the target image according to the additional spatial encoding information provided by the sensitivity distribution of the radio frequency receiving array coil group.

[0069] Wherein, the definition of coil sensitivity is as follows: the voltage induced in the receiving coil near the measured object generated by the magnetic resonance signal is closely related to its corresponding spatial position. The difference in signal strength due to spatial position is called coil sensitivity. The additional spatial encoding information provided by the sensitivity distribution of the radio frequency receiving array coil group refers to the difference in signal strength due to spatial position of different objects.

[0070] Corresponding to the number of driving matrix coils, the number of radio frequency receiving array coils contained in the radio frequency receiving array coil group is half of the number of gradient matrix coils.

[0071] In Figure 1 Step S200, further considering that the process of forming a dynamic encoding field from a static encoding field needs to be sinusoidally modulated, so that different spatial position imaging voxels have different encoding information. The specific sinusoidal modulation is described in detail with reference to the embodiment shown in Figure 2 .

[0072] With reference to Figure 2 , performing sinusoidal modulation of the coil unit driving current amplitude, so that the current amplitude of all coil units changes within the above-mentioned sinusoidal period, generating a dynamic encoding field includes:

[0073] Step S210, when the preset time node is a time node located after the preset first time node and the time difference between the preset first time node is a preset time difference multiple, the driving current initial value of each channel is again given a half-cycle sinusoidal modulation. Specifically as follows:

[0074]

[0075] Wherein, q is a non-linear encoding field ordinal, q = 0, 1, …, N-1, representing different time points; step depends on the total number of encoding field changes N: step = 2π / N.

[0076] Wherein, the time difference between the preset first time node and the initial time node can be 10 seconds or 20 seconds, and the specific time difference can be set according to the needs.

[0077] Step S220, obtaining a dynamic encoding field.

[0078] After step S210 and before step S220, further considering that the phase information of the signal generated by all position imaging pixels needs to be modulated several times, it is more troublesome, and further considering that the phase information of the signal generated by all position imaging pixels can be presented by one modulation, specifically as follows. Figure 2 A non-linear encoding imaging method further includes a step located after the driving current initial value of each channel is again given a half-cycle sinusoidal modulation and before the dynamic encoding field is obtained, specifically as follows.

[0079] Step S230, the driving current initial value of each channel is given a sinusoidal modulation with the following period, specifically as follows:

[0080] Wherein, Ns is the total number of sampling points. Specifically, after the above modulation, the current of a channel changes with time as shown in

[0081] , which shows different sinusoidal distributions at one time, that is, one modulation can obtain the phase information of the signal generated by all position imaging pixels. Figure 4

[0082] In step S300 of Figure 1 , further considering that in the process of obtaining the target image and reconstructing, how to further specifically reconstruct the target image is needed, and specific reference is made to the embodiment shown in Figure 5 for detailed description.

[0083] Referring to Figure 5 , analyzing the obtaining of the target image and the reconstruction includes:

[0084] ​Step S310 : Acquire additional spatial encoding information and nuclear magnetic resonance signals provided by the sensitivity distribution of each radio frequency receiving coil unit.

[0085] Step S320 , based on the relationship followed by the nuclear magnetic resonance signal, reverse analysis is performed to obtain the target image and reconstruct it.

[0086] Among them, the relationship that the nuclear magnetic resonance signal follows is as follows:

[0087]

[0088] Among them, m(r) is the target image, c j (r) is the sensitivity distribution of the jth RF receiving coil unit.

[0089] The solution for m(r) is as follows:

[0090] Will Simplified to s = Em; where E is the encoding matrix, including c j (r) and e index terms; s is the signal matrix; m is the target matrix; the preset iterative calculation formula is used to perform inverse analysis to obtain the target matrix.

[0091] Among them, the preset iterative calculation formula is as follows:

[0092] Where n represents the number of iterations, is the nth estimate, λ is the iteration parameter, * denotes the complex conjugate, brackets denote the inner product, and the double bar denotes the vector norm.

[0093] Reference Figure 6 , the embodiment of the present application further provides an image reconstruction system under nonlinear coding, specifically comprising:

[0094] Acquisition module 1 acquires the sub-encoding fields of the coil units uniformly distributed around the Z axis, so that the current amplitudes of all coil units are distributed on a sinusoidal curve of one period, and superposition generates a static encoding field;

[0095] Dynamic coding field forming module 2 performs sinusoidal modulation of the coil unit driving current amplitude, so that the current amplitude of all coil units changes within the above sinusoidal period, thereby generating a dynamic coding field;

[0096] The target image reconstruction module 3 receives the nuclear magnetic resonance signals generated by the dynamic coding field and its excitation through the radio frequency receiving array coil group, and analyzes and obtains the target image and reconstructs it based on the additional spatial coding information provided by the sensitivity distribution of the radio frequency receiving array coil group.

[0097] The embodiments of the present application are preferred embodiments of the present application, and are not intended to limit the protection scope of the present application, and thus: any equivalent changes made according to the structure, shape, principle of the present application should be covered within the protection scope of the present application.

Claims

1. A nonlinear coding imaging method, characterized in that: include: Obtain the sub-encoding field of the coil units uniformly distributed around the Z axis, so that the current amplitudes of all coil units are distributed on a sinusoidal curve of one period, and superimpose to generate a static encoding field; Performing sinusoidal modulation of the coil unit driving current amplitude, so that the current amplitude of all coil units changes within the above sinusoidal period, thereby generating a dynamic encoding field; The dynamic encoding field and the nuclear magnetic resonance signals generated by its excitation are received by the radio frequency receiving array coil group, and the target image is analyzed and reconstructed based on the additional spatial encoding information provided by the sensitivity distribution of the radio frequency receiving array coil group; Obtain the sub-encoding field of the coil units uniformly distributed around the Z axis so that the current amplitudes of all coil units are distributed on a sinusoidal curve of one period. The static encoding field is generated by superposition as follows: The coil unit group uniformly distributed around the Z axis is independently controlled to generate a static encoding field. The number of coils contained in the coil unit group is N. k , the specific static coding field formation formula is as follows: Among them, b i (r) is the sub-encoding field generated by coil unit i under unit current driving, r is the spatial position variable; I i (t) represents the driving current applied to the corresponding coil unit i at time t; b nl (t, r) is the static coding field generated by superposition; Among them, when time t is t0, the amplitude of the driving current applied to the corresponding coil unit i obeys the sine distribution, which is as follows: I i (t0) = I m sin(2π / N k *i); among them, I m Indicates the maximum current amplitude; Get static encoding field; Performing sinusoidal modulation of the coil unit driving current amplitude so that the current amplitude of all coil units changes within the above sinusoidal period, generating a dynamic encoding field includes: When the preset time node is a time node that is located after the preset first time node and the time difference between the preset first time node and the preset first time node is a multiple of the preset interval time, the initial value of the driving current of each channel is again given a half-cycle sinusoidal modulation, specifically as follows: Where q is the nonlinear coding field number, q = 0, 1, ..., N-1, representing different time points; step depends on the total number of coding field changes N: step = 2π / N; Get dynamic encoding field; The NMR signal follows the following relationship: Among them, s j (q) is the signal collected by the jth RF receiving channel in the entire imaging space V, m(r) is the target image, c j (r) is the sensitivity distribution of the jth RF receiving coil unit; i is a unit imaginary number, γ is the magnetic gyrometry ratio; m(r) is solved as follows: Will Simplified to s = Em; where E is the encoding matrix, including c j (r) and e index terms; s is the signal matrix; m is the target matrix; The preset iterative calculation formula is used to invert and analyze the target matrix.

2. The nonlinear coding imaging method according to claim 1, wherein: The number of coil units uniformly distributed around the Z axis is an even number, and the driving currents of the symmetrical coil units are always the same in magnitude and opposite in direction, and the number of driving sources is half the number of coil units.

3. A nonlinear coding imaging method according to claim 2, characterized in that: The method further includes the following steps after the initial driving current value of each channel is again given a half-cycle sinusoidal modulation and before the dynamic coding field is acquired: The initial driving current value of each channel is given a sinusoidal modulation with the following period, as follows: Where Ns is the total number of sampling points.

4. The nonlinear coding imaging method according to claim 3, wherein: Analyzing and acquiring target images and reconstructing them include: Acquire additional spatial encoding information and nuclear magnetic resonance signals provided by the sensitivity distribution of each radio frequency receiving coil unit; According to the relationship followed by the nuclear magnetic resonance signal, the target image is acquired through reverse analysis and reconstructed.

5. The nonlinear encoding imaging method according to claim 4, characterized in that: The preset iterative calculation formula is as follows: Where n represents the number of iterations, and are the estimated values ​​of the nth and n+1th images m, respectively. is the i-th row of the received signal matrix, is the i-th row of the encoding matrix, λ is the iteration parameter, * represents the complex conjugate, brackets represent inner products, and double bars represent vector norms.

6. An image reconstruction system under nonlinear coding, characterized in that: include: An acquisition module (1) acquires the sub-encoding fields of the coil units uniformly distributed around the Z axis, so that the current amplitudes of all the coil units are distributed on a sinusoidal curve of one period, and superimposes them to generate a static encoding field; A dynamic coding field forming module (2) performs sinusoidal modulation of the coil unit driving current amplitude, so that the current amplitude of all coil units changes within the above-mentioned sinusoidal period, thereby generating a dynamic coding field; A target image reconstruction module (3) receives the nuclear magnetic resonance signal generated by the dynamic coding field and its excitation through the radio frequency receiving array coil group, and analyzes and obtains the target image and reconstructs it based on the additional spatial coding information provided by the sensitivity distribution of the radio frequency receiving array coil group; Obtain the sub-encoding field of the coil units uniformly distributed around the Z axis so that the current amplitudes of all coil units are distributed on a sinusoidal curve of one period. The static encoding field is generated by superposition as follows: The coil unit group uniformly distributed around the Z axis is independently controlled to generate a static encoding field. The number of coils contained in the coil unit group is N. k , the specific static coding field formation formula is as follows: Among them, b i (r) is the sub-encoding field generated by coil unit i under unit current driving, r is the spatial position variable; I i (t) represents the driving current applied to the corresponding coil unit i at time t; b nl (t, r) is the static coding field generated by superposition; Among them, when time t is t0, the amplitude of the driving current applied to the corresponding coil unit i obeys the sine distribution, which is as follows: I i (t0) = I m sin(2π / N k *i); among them, I m Indicates the maximum current amplitude; Get static encoding field; Performing sinusoidal modulation of the coil unit driving current amplitude so that the current amplitude of all coil units changes within the above sinusoidal period, generating a dynamic encoding field includes: When the preset time node is a time node that is located after the preset first time node and the time difference between the preset first time node and the preset first time node is a multiple of the preset interval time, the initial value of the driving current of each channel is again given a half-cycle sinusoidal modulation, specifically as follows: Where q is the nonlinear coding field number, q = 0, 1, ..., N-1, representing different time points; step depends on the total number of coding field changes N: step = 2π / N; Get dynamic encoding field; The NMR signal follows the following relationship: Among them, s j (q) is the signal collected by the jth RF receiving channel in the entire imaging space V, m(r) is the target image, c j (r) is the sensitivity distribution of the jth RF receiving coil unit; i is a unit imaginary number, γ is the magnetic gyro ratio; The solution for m(r) is as follows: Will Simplified to s = Em; where E is the encoding matrix, including c j (r) and e index terms; s is the signal matrix; m is the target matrix; The preset iterative calculation formula is used to invert and analyze the target matrix.

Images