CN112014781A - Phase correction method and device for magnetic resonance echo signals, computer equipment and computer readable storage medium - Google Patents
Phase correction method and device for magnetic resonance echo signals, computer equipment and computer readable storage medium Download PDFInfo
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Abstract
The invention relates to the technical field of nuclear magnetic resonance imaging, and discloses a phase correction method, a phase correction device, computer equipment and a computer readable storage medium for magnetic resonance echo signals, which can correct the phase of the acquired echo signals from the aspect of a software layer, firstly, acquiring a plurality of magnetic resonance echo signals containing ringing signals, then taking the ringing signal with the maximum signal intensity as a reference signal, estimating the compensation phase of each magnetic resonance echo signal in the plurality of magnetic resonance echo signals, and finally, performing phase correction on the magnetic resonance echo signals of non-ringing signals according to the compensation phase, therefore, the phase jitter phenomenon can be obviously eliminated, the signal acquisition precision is ensured not to be influenced, the corrected magnetic resonance echo signals are favorable for subsequent reconstruction, artifacts caused by phase jitter are avoided, and the correctness of the final nuclear magnetic resonance imaging result is ensured.
Description
Technical Field
The invention belongs to the technical field of nuclear magnetic resonance imaging, particularly relates to a magnetic resonance spectrometer technology, and particularly relates to a phase correction method and device of a magnetic resonance echo signal, computer equipment and a computer readable storage medium.
Background
The human body contains a very large number of hydrogen atoms, which themselves have magnetic field properties such that when the human body is placed in a strong and uniform static magnetic field, the hydrogen atoms absorb energy (excitation process) and are aligned in the direction of the magnetic field. When the magnetic field disappears, the energy absorbed by the atomic nuclei is released and reflected as coil current, which is the echo signal to be acquired in the magnetic resonance spectrometer technique. In addition, in the actual excitation process, the signals can be acquired through not only a uniform magnetic field but also codes in different directions, and finally, the images are restored through a reconstruction algorithm.
The magnetic resonance spectrometer controls the transmission and reception of radio frequency pulses and gradient signals, and is a core component for realizing a magnetic resonance scanning function, wherein the magnetic resonance spectrometer has very high requirements on the time of the signals and needs to be accurate to a nanosecond level. At present, for the purposes of improving development speed, reducing development cost and the like, a universal hardware platform is generally adopted to realize a spectrometer, but for a low-cost nuclear magnetic resonance system realized based on the universal hardware platform, due to the design scheme of the universal hardware platform, the magnetic resonance characteristics are not considered, so that the time control precision of hardware in the signal transmitting and receiving process cannot reach a nanosecond level, phase jitter is brought (the phase jitter has certain regularity, namely from the actual acquisition result, a transmitted signal has delay, the delay can be fitted into a linear relationship), meanwhile, an echo signal also has phase jitter, the regularity is the same as the transmitted signal, and the linear relationship is also presented), and the precision of signal acquisition and the final nuclear magnetic resonance imaging result are influenced.
Disclosure of Invention
In order to solve the problem that the acquired magnetic resonance echo signals have certain phase jitter phenomenon in the conventional nuclear magnetic resonance system realized based on a generalized hardware platform, which can affect the signal acquisition precision and the final nuclear magnetic resonance imaging result, the invention aims to provide a method and a device for correcting the phase of the magnetic resonance echo signals, computer equipment and a computer readable storage medium.
In a first aspect, the present invention provides a method for correcting a phase of a magnetic resonance echo signal, including:
acquiring a plurality of magnetic resonance echo signals that are discrete in a time domain, wherein at least one ringing signal is present in the plurality of magnetic resonance echo signals;
taking the ringing signal with the strongest signal in the at least one ringing signal as a reference signal, and estimating the compensation phase of each magnetic resonance echo signal in the plurality of magnetic resonance echo signals;
and performing phase compensation according to the corresponding compensation phase aiming at each magnetic resonance echo signal which is not a ringing signal in the plurality of magnetic resonance echo signals to obtain a phase-corrected magnetic resonance echo signal.
Based on the above invention, the phase correction can be performed on the acquired echo signals from the aspect of a software layer, that is, a plurality of magnetic resonance echo signals including a ringing signal are acquired first, then the ringing signal with the maximum signal intensity is used as a reference signal, the compensation phase of each magnetic resonance echo signal in the plurality of magnetic resonance echo signals is estimated, and finally the phase correction is performed on the magnetic resonance echo signals of non-ringing signals according to the compensation phase, so that the phase jitter phenomenon can be obviously eliminated, the accuracy of signal acquisition is ensured not to be affected, the corrected magnetic resonance echo signals are favorable for subsequent reconstruction, artifacts (false images formed in images due to signal distortion caused by motion or eddy currents and the like) caused by phase jitter are avoided, and the correctness of the final nuclear magnetic resonance imaging result is ensured. In addition, the phase correction method can be suitable for the magnetic resonance spectrometer developed based on a general hardware platform, is beneficial to shortening the development period and reducing the hardware cost, and is convenient for practical application and popularization.
In one possible design, acquiring a plurality of magnetic resonance echo signals that are discrete in the time domain includes:
opening the magnetic resonance acquisition window immediately after the magnetic resonance emission window is finished;
and maintaining the magnetic resonance acquisition window, and acquiring discrete magnetic resonance echo signals in a time domain through the magnetic resonance acquisition window until normal acquisition work is completed.
In one possible design, the estimating a compensation phase of each of the plurality of magnetic resonance echo signals using a ring signal with a strongest signal of the at least one ring signal as a reference signal includes:
performing Fourier transform on each of the multiple magnetic resonance echo signals to obtain a corresponding first magnetic resonance echo frequency spectrum Fr(k,n)：
Fr(k,n)＝FFT{Sr(t,n)}
In the formula, FFT { } represents a Fourier transform function, Sr(t, n) represents a magnetic resonance echo signal corresponding to the number n among the plurality of magnetic resonance echo signals, t represents time, n represents a unique number corresponding to the magnetic resonance echo signal, and k represents a discrete sampling point number in the fourier transform;
at all of the first magnetic resonance echo frequency spectrum Fr(k, n), selecting the magnetic resonance echo spectrum F corresponding to the ringing signal with the strongest signalr(k,Nr) Wherein N isrA unique number representing the ringing signal corresponding to the signal being strongest;
subjecting the magnetic resonance echo spectrum Fr(k,Nr) As a reference spectrum, for each of the first magnetic resonance echo spectra Fr(k, n) respectively carrying out normalization processing to obtain corresponding normalized magnetic resonance echo frequency spectrums H (k, n):
in the formula, gammak,nRepresenting the amplitude of the magnetic resonance echo signal corresponding to the number n at the kth discrete sampling point number, e representing the base of the natural logarithm, j representing the complex number, ωnRepresents the phase change rate of the magnetic resonance echo signal corresponding to the number n;
carrying out phase difference on the normalized magnetic resonance echo frequency spectrum H (k, n) according to the following formula to obtain a phase difference component delta H (k, n) of the numbers of two adjacent discrete sampling points:
in the formula, H*(k +1, n) represents the conjugate function corresponding to H (k +1, n), H (k +1, n) represents the normalized magnetic resonance echo spectrum of the magnetic resonance echo signal corresponding to the number n at the (k + 1) th discrete sampling point number, γk+1,nRepresenting the amplitude of the magnetic resonance echo signal corresponding to the number n on the (k + 1) th discrete sampling point number;
all the phase difference components Delta H (k, n) are summed, and the total phase difference quantity Delta phi is calculated0(n)：
In the formula (I), the compound is shown in the specification,
representing the amplitude estimate of the magnetic resonance echo signal corresponding to the number n,
a phase change rate estimation value representing the magnetic resonance echo signal corresponding to the number n;
from the normalized magnetic resonance echo spectrum H (k, n) and the phase differenceFractional total amount of delta phi0(n) calculating the initial phase delta phi of the compensation phase according to the following formula1(n)：
Where K denotes the total number of discrete sampling points, θ, in a magnetic resonance echo signalnAn initial phase representing the magnetic resonance echo signal corresponding to the number n and compensating the phase;
for each of the plurality of magnetic resonance echo signals, a corresponding compensation phase φ (k, n) is calculated according to the following formula:
in one possible design, performing phase compensation on each magnetic resonance echo signal, which is a non-ringing signal, of the plurality of magnetic resonance echo signals according to a corresponding compensation phase to obtain a phase-corrected magnetic resonance echo signal, includes:
respectively carrying out Fourier transform on each magnetic resonance echo signal which is not a ringing signal in the plurality of magnetic resonance echo signals to obtain a corresponding second magnetic resonance echo frequency spectrum Fa(k,n)：
Fa(k,n)＝FFT{Sa(t,n)}
In the formula, FFT { } represents a Fourier transform function, Sa(t, n) represents a magnetic resonance echo signal corresponding to the number n among the plurality of magnetic resonance echo signals, t represents time, n represents a unique number corresponding to the magnetic resonance echo signal, and k represents a discrete sampling point number in the fourier transform;
aiming at each magnetic resonance echo signal which is not a ringing signal in the plurality of magnetic resonance echo signals, calculating to obtain a corresponding frequency spectrum F after phase compensation according to the following formulac(k,n)：
Fc(k,n)＝Fa(k,n)φ(k,n)
In the formula, phi (k, n) represents the compensation phase of the magnetic resonance echo signal corresponding to the number n;
for each magnetic resonance echo signal which is not a ringing signal in the plurality of magnetic resonance echo signals, corresponding frequency spectrum F after phase compensation is performedcAnd (k, n) performing inverse Fourier transform to obtain a phase-corrected magnetic resonance echo signal.
In a second aspect, the invention provides a phase correction device for a magnetic resonance echo signal, which comprises a signal acquisition unit, a phase estimation unit and a phase compensation unit, wherein the signal acquisition unit, the phase estimation unit and the phase compensation unit are sequentially in communication connection;
the signal acquisition unit is used for acquiring a plurality of magnetic resonance echo signals which are discrete in a time domain, wherein at least one ringing signal exists in the plurality of magnetic resonance echo signals;
the phase estimation unit is configured to estimate a compensation phase of each of the plurality of magnetic resonance echo signals by using a ringing signal with a strongest signal among the at least one ringing signal as a reference signal;
and the phase compensation unit is used for performing phase compensation on each magnetic resonance echo signal which is a non-ringing signal in the plurality of magnetic resonance echo signals according to the corresponding compensation phase to obtain a phase-corrected magnetic resonance echo signal.
In one possible design, the signal acquisition unit comprises an acquisition window opening subunit and an acquisition window maintaining subunit which are in communication connection;
the acquisition window opening subunit is used for immediately opening the magnetic resonance acquisition window after the magnetic resonance emission window is finished;
and the acquisition window maintaining subunit is used for maintaining the magnetic resonance acquisition window, and acquiring discrete magnetic resonance echo signals in a time domain through the magnetic resonance acquisition window until normal acquisition work is completed.
In one possible design, the phase estimation unit includes a first fourier transform subunit, an echo spectrum selection subunit, a normalization processing subunit, a phase difference summation subunit, an initial phase calculation subunit and a compensation phase calculation subunit, which are sequentially connected in communication;
the first fourier transform subunit is configured to perform fourier transform on each of the multiple magnetic resonance echo signals to obtain a corresponding first magnetic resonance echo frequency spectrum Fr(k,n)：
Fr(k,n)＝FFT{Sr(t,n)}
In the formula, FFT { } represents a Fourier transform function, Sr(t, n) represents a magnetic resonance echo signal corresponding to the number n among the plurality of magnetic resonance echo signals, t represents time, n represents a unique number corresponding to the magnetic resonance echo signal, and k represents a discrete sampling point number in the fourier transform;
the echo spectrum selection subunit is used for selecting all the first magnetic resonance echo spectrums Fr(k, n), selecting the magnetic resonance echo spectrum F corresponding to the ringing signal with the strongest signalr(k,Nr) Wherein N isrA unique number representing the ringing signal corresponding to the signal being strongest;
the normalization processing subunit is used for converting the magnetic resonance echo frequency spectrum Fr(k,Nr) As a reference spectrum, for each of the first magnetic resonance echo spectra Fr(k, n) respectively carrying out normalization processing to obtain corresponding normalized magnetic resonance echo frequency spectrums H (k, n):
in the formula, gammak,nRepresenting the amplitude of the magnetic resonance echo signal corresponding to the number n at the kth discrete sampling point number, e representing the base of the natural logarithm, j representing the complex number, ωnRepresents the phase change rate of the magnetic resonance echo signal corresponding to the number n;
the phase difference processing subunit is configured to perform phase difference on the normalized magnetic resonance echo spectrum H (k, n) according to the following formula to obtain a phase difference component Δ H (k, n) between two adjacent discrete sampling points:
in the formula, H*(k +1, n) represents the conjugate function corresponding to H (k +1, n), H (k +1, n) represents the normalized magnetic resonance echo spectrum of the magnetic resonance echo signal corresponding to the number n at the (k + 1) th discrete sampling point number, γk+1,nRepresenting the amplitude of the magnetic resonance echo signal corresponding to the number n on the (k + 1) th discrete sampling point number;
the phase difference summation subunit is configured to sum all the phase difference components Δ H (k, n) and calculate a phase
Total difference of delta phi0(n)：
In the formula (I), the compound is shown in the specification,
representing the amplitude estimate of the magnetic resonance echo signal corresponding to the number n,
a phase change rate estimation value representing the magnetic resonance echo signal corresponding to the number n;
the initial phase calculating subunit calculates the initial phase difference according to the normalized magnetic resonance echo spectrum H (k, n) and the phase difference total amount delta phi0(n) calculating the initial phase delta phi of the compensation phase according to the following formula1(n)：
Where K denotes the total number of discrete sampling points, θ, in a magnetic resonance echo signalnAn initial phase representing the magnetic resonance echo signal corresponding to the number n and compensating the phase;
the compensation phase calculation subunit is used for calculating the magnetic resonance signals of the plurality of magnetic resonance echo signalsAnd (3) calculating the corresponding compensation phase phi (k, n) according to the following formula:
in one possible design, the phase compensation unit includes a second fourier transform subunit, an echo spectrum compensation subunit and an inverse fourier transform subunit, which are sequentially connected in communication;
the second fourier transform subunit is configured to perform fourier transform on each magnetic resonance echo signal that is not a ringing signal in the plurality of magnetic resonance echo signals, to obtain a corresponding second magnetic resonance echo frequency spectrum Fa(k,n)：
Fa(k,n)＝FFT{Sa(t,n)}
In the formula, FFT { } represents a Fourier transform function, Sa(t, n) represents a magnetic resonance echo signal corresponding to the number n among the plurality of magnetic resonance echo signals, t represents time, n represents a unique number corresponding to the magnetic resonance echo signal, and k represents a discrete sampling point number in the fourier transform;
the echo spectrum compensation subunit is configured to calculate, for each magnetic resonance echo signal that is not a ringing signal among the multiple magnetic resonance echo signals, a corresponding spectrum F after phase compensation according to the following formulac(k,n)：
Fc(k,n)＝Fa(k,n)φ(k,n)
In the formula, phi (k, n) represents the compensation phase of the magnetic resonance echo signal corresponding to the number n;
the inverse fourier transform subunit is configured to, for each magnetic resonance echo signal that is not a ringing signal in the plurality of magnetic resonance echo signals, apply the corresponding frequency spectrum F after phase compensationcAnd (k, n) performing inverse Fourier transform to obtain a phase-corrected magnetic resonance echo signal.
In a third aspect, the present invention provides a computer device, comprising a memory and a processor, wherein the memory is used for storing a computer program, and the processor is used for reading the computer program and executing the phase correction method according to the first aspect or any one of the possible designs of the first aspect.
In a fourth aspect, the present invention provides a computer-readable storage medium having stored thereon instructions which, when executed on a computer, perform the phase correction method as described above in the first aspect or any one of the possible designs of the first aspect.
In a fifth aspect, the present invention provides a computer program product comprising instructions which, when run on a computer, cause the computer to perform the phase correction method as described above in the first aspect or any one of the possible designs of the first aspect.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic flow chart of a phase correction method for magnetic resonance echo signals according to the present invention.
Fig. 2 is a schematic diagram of an application structure of the open-source real-time spectrometer developed based on the dragon fruit development board provided by the invention.
Fig. 3 is an exemplary diagram of a ring signal provided by the present invention.
Figure 4 is an exemplary illustration of a magnetic resonance transmit window and a magnetic resonance acquisition window provided by the present invention.
Fig. 5 is a diagram of a magnetic resonance echo signal including a ringing signal and a frequency spectrum provided by the present invention, wherein (a) is a signal diagram and (b) is a frequency spectrum diagram.
Fig. 6 is a magnetic resonance echo signal and a spectrogram obtained by the phase correction method according to the present invention, wherein (a) is a signal diagram and (b) is a spectrogram.
Fig. 7 is a magnetic resonance echo signal and a frequency spectrum obtained without using the phase correction method of the present invention, wherein (a) is a signal diagram and (b) is a frequency spectrum diagram.
Fig. 8 is a schematic structural diagram of a phase correction device for magnetic resonance echo signals according to the present invention.
Fig. 9 is a schematic structural diagram of a computer device provided by the present invention.
Detailed Description
The invention is further described with reference to the following figures and specific embodiments. It should be noted that the description of the embodiments is provided to help understanding of the present invention, but the present invention is not limited thereto. Specific structural and functional details disclosed herein are merely illustrative of example embodiments of the invention. This invention may, however, be embodied in many alternate forms and should not be construed as limited to the embodiments set forth herein.
It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of example embodiments of the present invention.
It should be understood that, for the term "and/or" as may appear herein, it is merely an associative relationship that describes an associated object, meaning that three relationships may exist, e.g., a and/or B may mean: a exists alone, B exists alone, and A and B exist at the same time; for the term "/and" as may appear herein, which describes another associative object relationship, it means that two relationships may exist, e.g., a/and B, may mean: a exists independently, and A and B exist independently; in addition, for the character "/" that may appear herein, it generally means that the former and latter associated objects are in an "or" relationship.
It will be understood that when an element is referred to herein as being "connected," "connected," or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may be present. Conversely, if a unit is referred to herein as being "directly connected" or "directly coupled" to another unit, it is intended that no intervening units are present. In addition, other words used to describe the relationship between elements should be interpreted in a similar manner (e.g., "between … …" versus "directly between … …", "adjacent" versus "directly adjacent", etc.).
It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises," "comprising," "includes" and/or "including," when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, numbers, steps, operations, elements, components, and/or groups thereof.
It should also be noted that, in some alternative designs, the functions/acts noted may occur out of the order noted in the figures. For example, two figures shown in succession may, in fact, be executed substantially concurrently, or the figures may sometimes be executed in the reverse order, depending upon the functionality/acts involved.
It should be understood that specific details are provided in the following description to facilitate a thorough understanding of example embodiments. However, it will be understood by those of ordinary skill in the art that the example embodiments may be practiced without these specific details. For example, systems may be shown in block diagrams in order not to obscure the examples in unnecessary detail. In other instances, well-known processes, structures and techniques may be shown without unnecessary detail in order to avoid obscuring example embodiments.
As shown in fig. 1 to 7, the phase correction method for magnetic resonance echo signals provided in the first aspect of this embodiment may be, but is not limited to, applied to a nuclear magnetic resonance system implemented based on a generalized hardware platform. For example, as shown in fig. 2, in an Open-source Real-time spectrometer (OCRA) developed based on a dragon fruit development board, main control capability of the dragon fruit development board is provided by an on-chip system Xilinx ZYNQ XC7Z010 on which an ARM (advanced RISC machine) processor and an FPGA (field Programmable Gate array) are mounted, and a control logic related to the spectrometer is to control a hardware logic on the FPGA through a Linux C program on the ARM processor, so as to implement control of transmitting and receiving signals, and a specific working principle is as follows: firstly, on the FPGA, a radio frequency RF (radio frequency) inlet and a radio frequency RF outlet of the peripheral equipment are respectively used for transmitting and receiving radio frequency signals, and an expansion interface of the peripheral equipment is used for generating encoding signals in XYZ three directions; secondly, the OCRA provides a sequence development language similar to assembly, the sequence can be described by using the sequence development language to form a sequence code file, and the scanning sequence can be realized by using the characteristic; finally, the Linux C program can complete the analysis of the sequence code file through an interface provided by the OCRA, the sequence code file is compiled into binary instructions which can be identified by the FPGA, and the FPGA specifically executes the binary instructions, so that the control of signal transmission and signal receiving is realized. Due to the fact that configuration operation exists in the command execution process of the FPGA, time overhead can be caused by the configuration operation, the time overhead cannot reach a nanosecond level or below, actually acquired echo signals can be affected, and therefore phase jitter of the echo signals is brought. Since this phase jitter cannot be avoided from the perspective of hardware, it can only be avoided from the software level, which is a technical solution for performing phase correction on the acquired magnetic resonance echo signals from the perspective of software level in this embodiment. The method for correcting the phase of the magnetic resonance echo signal may include, but is not limited to, the following steps S101 to S103.
S101, a plurality of magnetic resonance echo signals which are discrete in a time domain are obtained, wherein at least one ringing signal exists in the plurality of magnetic resonance echo signals.
In step S101, the plurality of magnetic resonance echo signals may be echo signals acquired in history or echo signals acquired in real time. Because the magnetic resonance echo signal which is actually acquired and can be used for nuclear magnetic resonance imaging has the characteristics of low signal intensity and the like, if the signal is used as a phase reference, an accurate phase compensation result cannot be obtained, so that it is considered that a ringing signal (i.e. a ringing noise signal, which is a residual wave noise caused by a drastic change in signal amplitude and is also used as an acquired magnetic resonance echo signal in this embodiment, but needs to be removed in advance during mri) exists in the whole energy release process, as shown in fig. 3, because the signal strength of the ringing signal is relatively high, the signal phase thereof can be used as a phase reference for other magnetic resonance echo signals, so that in subsequent steps an accurate compensation of the phase estimation and phase correction is possible, so that at least one ringing signal needs to be present in the plurality of magnetic resonance echo signals.
In step S101, it is considered that, in the conventional process of acquiring a magnetic resonance echo signal, the ringing signal belonging to a noise signal is not acquired in order to avoid introducing noise, and therefore, as shown in fig. 4, signal acquisition is further performed according to steps S1011 to S1012 as follows: s1011, immediately opening a magnetic resonance acquisition window after the magnetic resonance emission window is finished; s1012, maintaining the magnetic resonance acquisition window, and acquiring discrete magnetic resonance echo signals in a time domain through the magnetic resonance acquisition window until normal acquisition work is completed. In steps S011 to S1012, the magnetic resonance emission window in which signals are emitted and the magnetic resonance acquisition window in which magnetic resonance echo signals are received are commonly used terms in the prior art. Compared with the conventional signal acquisition mode, in order to ensure that the ringing signal can be acquired, the magnetic resonance acquisition window needs to be opened in advance, namely, the magnetic resonance acquisition window is immediately opened after the magnetic resonance emission window is finished until the normal acquisition work is finished. In addition, the specific opening time of the magnetic resonance acquisition window can be advanced or delayed properly, so long as a complete ringing signal can be acquired.
And S102, taking the ringing signal with the strongest signal in the at least one ringing signal as a reference signal, and estimating the compensation phase of each magnetic resonance echo signal in the plurality of magnetic resonance echo signals.
In step S102, if only one ringing signal is included in the plurality of magnetic resonance echo signals, the ringing signal is used as a reference signal. Preferably, the method includes, but is not limited to, the following steps S1021 to S1027, where the ringing signal with the strongest signal in the at least one ringing signal is used as a reference signal, and the compensation phase of each of the plurality of magnetic resonance echo signals is estimated.
S1021, performing Fourier transform on each magnetic resonance echo signal in the plurality of magnetic resonance echo signals to obtain a corresponding first magnetic resonance echo frequency spectrum Fr(k,n)：
Fr(k,n)＝FFT{Sr(t,n)}
In the formula, FFT { } represents a Fourier transform function, Sr(t, n) represents a magnetic resonance echo signal corresponding to the number n among the plurality of magnetic resonance echo signals, t represents time, n represents a unique number corresponding to the magnetic resonance echo signal, and k represents a discrete sample point number in the fourier transform.
S1022. in all the first magnetic resonance echo frequency spectrums Fr(k, n), selecting the magnetic resonance echo spectrum F corresponding to the ringing signal with the strongest signalr(k,Nr) Wherein N isrA unique number representing the ring signal corresponding to the strongest signal.
S1023, using the magnetic resonance echo frequency spectrum Fr(k,Nr) As a reference spectrum, for each of the first magnetic resonance echo spectra Fr(k, n) respectively carrying out normalization processing to obtain corresponding normalized magnetic resonance echo frequency spectrums H (k, n):
in the formula, gammak,nRepresenting the amplitude of the magnetic resonance echo signal corresponding to the number n at the kth discrete sampling point number, e representing the base of the natural logarithm, j representing the complex number, ωnThe pair of representation and number nThe rate of change of phase of the corresponding magnetic resonance echo signal;
s1024, performing phase difference on the normalized magnetic resonance echo spectrum H (k, n) according to the following formula to obtain a phase difference component delta H (k, n) of the numbers of two adjacent discrete sampling points:
in the formula, H*(k +1, n) represents the conjugate function corresponding to H (k +1, n), H (k +1, n) represents the normalized magnetic resonance echo spectrum of the magnetic resonance echo signal corresponding to the number n at the (k + 1) th discrete sampling point number, γk+1,nIndicating the amplitude of the magnetic resonance echo signal corresponding to the number n at the (k + 1) th discrete sample point number. In addition, in an ideal case, though ωnIs a fixed value, and in the actual calculation process, the phase difference component Δ H (k, n) needs to be further processed to obtain ωnIs estimated value of
S1025, summing all the phase difference components delta H (k, n), and calculating to obtain the total phase difference quantity delta phi0(n)：
In the formula (I), the compound is shown in the specification,
representing the amplitude estimate of the magnetic resonance echo signal corresponding to the number n,
which represents the estimated phase change rate of the magnetic resonance echo signal corresponding to the number n.
S1026. according to the normalized magnetic resonance echo frequency spectrum H (k, n) and the phase difference total quantity delta phi0(n) calculated according to the following formulaInitial phase to compensated phase delta phi1(n)：
Where K denotes the total number of discrete sampling points, θ, in a magnetic resonance echo signalnAn initial phase of the magnetic resonance echo signal corresponding to the number n and compensated for is indicated.
S1027, aiming at each magnetic resonance echo signal in the magnetic resonance echo signals, calculating a corresponding compensation phase phi (k, n) according to the following formula:
and S103, performing phase compensation on each magnetic resonance echo signal which is a non-ringing signal in the plurality of magnetic resonance echo signals according to the corresponding compensation phase to obtain a phase-corrected magnetic resonance echo signal.
In the step S103, it is optimized to perform phase compensation on each magnetic resonance echo signal that is not a ringing signal among the plurality of magnetic resonance echo signals according to the corresponding compensation phase to obtain a phase-corrected magnetic resonance echo signal, including but not limited to the following steps S1031 to S1033.
S1031, respectively carrying out Fourier transform on each magnetic resonance echo signal which is not a ringing signal in the plurality of magnetic resonance echo signals to obtain a corresponding second magnetic resonance echo frequency spectrum Fa(k,n)：
Fa(k,n)＝FFT{Sa(t,n)}
In the formula, FFT { } represents a Fourier transform function, Sa(t, n) represents a magnetic resonance echo signal corresponding to the number n among the plurality of magnetic resonance echo signals, t represents time, n represents a unique number corresponding to the magnetic resonance echo signal, and k represents a discrete sample point number in the fourier transform.
S1032, aiming at each magnetic resonance echo signal which is not a ringing signal in the plurality of magnetic resonance echo signals, the following formula is adoptedCalculating to obtain a corresponding frequency spectrum F after phase compensationc(k,n)：
Fc(k,n)＝Fa(k,n)φ(k,n)
In the equation, [ phi ] (k, n) represents the compensation phase of the magnetic resonance echo signal corresponding to the number n.
S1033, aiming at each magnetic resonance echo signal which is not a ringing signal in the multiple magnetic resonance echo signals, corresponding frequency spectrum F after phase compensation is conductedcAnd (k, n) performing inverse Fourier transform to obtain a phase-corrected magnetic resonance echo signal.
Still taking the aforementioned open-source real-time spectrometer developed based on the dragon fruit development board as an example, a scan sequence may be specifically designed according to the magnetic resonance acquisition window designed in steps S1011 to S1012, and a magnetic resonance echo signal shown in (a) in fig. 5 and including a ringing signal is obtained by scanning through the scan sequence, and then a magnetic resonance echo spectrogram shown in (b) in fig. 5 is obtained through step S1021, and finally, the compensation phase Φ (k, n) is calculated through steps S1022 to S1027, and finally, through steps S1031 to S1033, the phase compensation may be performed on the magnetic resonance echo signal of the non-ringing signal according to the compensation phase, so as to obtain a phase-corrected magnetic resonance echo signal. The magnetic resonance echo signal and the frequency spectrum obtained based on the phase correction method of the present embodiment can be shown in (a) and (b) in fig. 6, while the magnetic resonance echo signal and the frequency spectrum which are directly collected without using the phase correction method of the present embodiment are shown in (a) and (b) in fig. 7, which shows that the phase jitter phenomenon is obviously eliminated by the technical solution of the present invention, and the accuracy of signal collection and the correctness of the final mri result are not affected.
Thus, by the phase correction scheme detailed in the above steps S101 to S103, the phase correction can be performed on the acquired echo signals from the perspective of software, firstly, acquiring a plurality of magnetic resonance echo signals containing ringing signals, then taking the ringing signal with the maximum signal intensity as a reference signal, estimating the compensation phase of each magnetic resonance echo signal in the plurality of magnetic resonance echo signals, and finally, performing phase correction on the magnetic resonance echo signals of non-ringing signals according to the compensation phase, therefore, the phase jitter phenomenon can be obviously eliminated, the signal acquisition precision is ensured not to be influenced, the corrected magnetic resonance echo signals are favorable for subsequent reconstruction, artifacts (signal distortion caused by movement or eddy current and the like and false images formed in images) are avoided being introduced due to the phase jitter, and the correctness of the final nuclear magnetic resonance imaging result is ensured. In addition, the phase correction method can be suitable for the magnetic resonance spectrometer developed based on a general hardware platform, is beneficial to shortening the development period and reducing the hardware cost, and is convenient for practical application and popularization.
As shown in fig. 8, a second aspect of this embodiment provides a virtual device for implementing the phase correction method according to any one of the first aspect or the possible designs of the first aspect, including a signal acquisition unit, a phase estimation unit, and a phase compensation unit, which are sequentially connected in a communication manner;
the signal acquisition unit is used for acquiring a plurality of magnetic resonance echo signals which are discrete in a time domain, wherein at least one ringing signal exists in the plurality of magnetic resonance echo signals;
the phase estimation unit is configured to estimate a compensation phase of each of the plurality of magnetic resonance echo signals by using a ringing signal with a strongest signal among the at least one ringing signal as a reference signal;
and the phase compensation unit is used for performing phase compensation on each magnetic resonance echo signal which is a non-ringing signal in the plurality of magnetic resonance echo signals according to the corresponding compensation phase to obtain a phase-corrected magnetic resonance echo signal.
In one possible design, the signal acquisition unit comprises an acquisition window opening subunit and an acquisition window maintaining subunit which are in communication connection;
the acquisition window opening subunit is used for immediately opening the magnetic resonance acquisition window after the magnetic resonance emission window is finished;
and the acquisition window maintaining subunit is used for maintaining the magnetic resonance acquisition window, and acquiring discrete magnetic resonance echo signals in a time domain through the magnetic resonance acquisition window until normal acquisition work is completed.
In one possible design, the phase estimation unit includes a first fourier transform subunit, an echo spectrum selection subunit, a normalization processing subunit, a phase difference summation subunit, an initial phase calculation subunit and a compensation phase calculation subunit, which are sequentially connected in communication;
the first fourier transform subunit is configured to perform fourier transform on each of the multiple magnetic resonance echo signals to obtain a corresponding first magnetic resonance echo frequency spectrum Fr(k,n)：
Fr(k,n)＝FFT{Sr(t,n)}
In the formula, FFT { } represents a Fourier transform function, Sr(t, n) represents a magnetic resonance echo signal corresponding to the number n among the plurality of magnetic resonance echo signals, t represents time, n represents a unique number corresponding to the magnetic resonance echo signal, and k represents a discrete sampling point number in the fourier transform;
the echo spectrum selection subunit is used for selecting all the first magnetic resonance echo spectrums Fr(k, n), selecting the magnetic resonance echo spectrum F corresponding to the ringing signal with the strongest signalr(k,Nr) Wherein N isrA unique number representing the ringing signal corresponding to the signal being strongest;
the normalization processing subunit is used for converting the magnetic resonance echo frequency spectrum Fr(k,Nr) As a reference spectrum, for each of the first magnetic resonance echo spectra Fr(k, n) respectively carrying out normalization processing to obtain corresponding normalized magnetic resonance echo frequency spectrums H (k, n):
in the formula, gammak,nRepresenting the amplitude of the magnetic resonance echo signal corresponding to the number n at the kth discrete sampling point number, e representing the base of the natural logarithm, j representing the complex number, ωnRepresents the phase change rate of the magnetic resonance echo signal corresponding to the number n;
the phase difference processing subunit is configured to perform phase difference on the normalized magnetic resonance echo spectrum H (k, n) according to the following formula to obtain a phase difference component Δ H (k, n) between two adjacent discrete sampling points:
in the formula, H*(k +1, n) represents the conjugate function corresponding to H (k +1, n), H (k +1, n) represents the normalized magnetic resonance echo spectrum of the magnetic resonance echo signal corresponding to the number n at the (k + 1) th discrete sampling point number, γk+1,nRepresenting the amplitude of the magnetic resonance echo signal corresponding to the number n on the (k + 1) th discrete sampling point number;
the phase difference summation subunit is configured to sum all the phase difference components Δ H (k, n) and calculate a phase
Total difference of delta phi0(n)：
In the formula (I), the compound is shown in the specification,
representing the amplitude estimate of the magnetic resonance echo signal corresponding to the number n,
a phase change rate estimation value representing the magnetic resonance echo signal corresponding to the number n;
the initial phase calculating subunit calculates the initial phase difference according to the normalized magnetic resonance echo spectrum H (k, n) and the phase difference total amount delta phi0(n) calculating the initial phase delta phi of the compensation phase according to the following formula1(n)：
In which K is represented byTotal number of discrete sampling points, theta, within the magnetic resonance echo signalnAn initial phase representing the magnetic resonance echo signal corresponding to the number n and compensating the phase;
the compensation phase calculation subunit is configured to calculate, for each of the plurality of magnetic resonance echo signals, a corresponding compensation phase Φ (k, n) according to the following formula:
in a possible design, the phase compensation unit includes a second fourier transform subunit, an echo spectrum compensation subunit and an inverse fourier transform subunit, which are sequentially connected in communication;
the second fourier transform subunit is configured to perform fourier transform on each magnetic resonance echo signal that is not a ringing signal in the plurality of magnetic resonance echo signals, to obtain a corresponding second magnetic resonance echo frequency spectrum Fa(k,n)：
Fa(k,n)＝FFT{Sa(t,n)}
In the formula, FFT { } represents a Fourier transform function, Sa(t, n) represents a magnetic resonance echo signal corresponding to the number n among the plurality of magnetic resonance echo signals, t represents time, n represents a unique number corresponding to the magnetic resonance echo signal, and k represents a discrete sampling point number in the fourier transform;
the echo spectrum compensation subunit is configured to calculate, for each magnetic resonance echo signal that is not a ringing signal among the multiple magnetic resonance echo signals, a corresponding spectrum F after phase compensation according to the following formulac(k,n)：
Fc(k,n)＝Fa(k,n)φ(k,n)
In the formula, phi (k, n) represents the compensation phase of the magnetic resonance echo signal corresponding to the number n;
the inverse fourier transform subunit is configured to, for each magnetic resonance echo signal that is not a ringing signal in the plurality of magnetic resonance echo signals, apply the corresponding frequency spectrum F after phase compensationc(k, n) inverse Fourier transformAnd obtaining a magnetic resonance echo signal with corrected phase.
For the working process, working details and technical effects of the foregoing apparatus provided in the second aspect of this embodiment, reference may be made to the phase correction method in any one of the first aspect and the first aspect, which is not described herein again.
As shown in fig. 9, a third aspect of the present embodiment provides a computer device for executing the phase correction method according to any one of the possible designs of the first aspect or the first aspect, and the computer device includes a memory and a processor, which are communicatively connected, where the memory is used to store a computer program, and the processor is used to read the computer program and execute the phase correction method according to any one of the possible designs of the first aspect or the first aspect. For example, the Memory may include, but is not limited to, a Random-Access Memory (RAM), a Read-Only Memory (ROM), a Flash Memory (Flash Memory), a First-in First-out (FIFO), and/or a First-in Last-out (FILO), and the like; the processor may not be limited to the microprocessor of the model number employing the STM32F105 family. In addition, the computer device may also include, but is not limited to, a power module, a display screen, and other necessary components.
For the working process, working details and technical effects of the foregoing computer device provided in the third aspect of this embodiment, reference may be made to the first aspect or any one of the possible designs of the phase correction method in the first aspect, which is not described herein again.
A fourth aspect of the present embodiment provides a computer-readable storage medium storing instructions including the phase correction method according to any one of the first aspect or any one of the possible designs of the first aspect, that is, the computer-readable storage medium has instructions stored thereon, and when the instructions are executed on a computer, the phase correction method according to any one of the possible designs of the first aspect or the first aspect is executed. The computer-readable storage medium refers to a carrier for storing data, and may include, but is not limited to, floppy disks, optical disks, hard disks, flash memories, flash disks and/or Memory sticks (Memory sticks), etc., and the computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices.
For the working process, the working details and the technical effects of the foregoing computer-readable storage medium provided in the fourth aspect of this embodiment, reference may be made to the first aspect or any one of the possible designs of the phase correction method in the first aspect, and details are not described herein again.
A fifth aspect of the present embodiment provides a computer program product comprising instructions which, when run on a computer, cause the computer to perform the phase correction method according to the first aspect or any one of the possible designs of the first aspect. The computer may be a general purpose computer, a special purpose computer, a network of computers, or other programmable devices.
The embodiments described above are merely illustrative, and may or may not be physically separate, if referring to units illustrated as separate components; if reference is made to a component displayed as a unit, it may or may not be a physical unit, and may be located in one place or distributed over a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: modifications may be made to the embodiments described above, or equivalents may be substituted for some of the features described. And such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Finally, it should be noted that the present invention is not limited to the above alternative embodiments, and that various other forms of products can be obtained by anyone in light of the present invention. The above detailed description should not be taken as limiting the scope of the invention, which is defined in the claims, and which the description is intended to be interpreted accordingly.
Claims (10)
1. A method for phase correction of magnetic resonance echo signals, comprising:
acquiring a plurality of magnetic resonance echo signals that are discrete in a time domain, wherein at least one ringing signal is present in the plurality of magnetic resonance echo signals;
taking the ringing signal with the strongest signal in the at least one ringing signal as a reference signal, and estimating the compensation phase of each magnetic resonance echo signal in the plurality of magnetic resonance echo signals;
and performing phase compensation according to the corresponding compensation phase aiming at each magnetic resonance echo signal which is not a ringing signal in the plurality of magnetic resonance echo signals to obtain a phase-corrected magnetic resonance echo signal.
2. The phase correction method of claim 1, wherein acquiring a plurality of magnetic resonance echo signals that are discrete in a time domain comprises:
opening the magnetic resonance acquisition window immediately after the magnetic resonance emission window is finished;
and maintaining the magnetic resonance acquisition window, and acquiring discrete magnetic resonance echo signals in a time domain through the magnetic resonance acquisition window until normal acquisition work is completed.
3. The method of phase correction according to claim 1, wherein estimating the compensated phase of each of the plurality of magnetic resonance echo signals using a ring signal with a strongest signal of the at least one ring signal as a reference signal comprises:
performing Fourier transform on each of the multiple magnetic resonance echo signals to obtain a corresponding first magnetic resonance echo frequency spectrum Fr(k,n)：
Fr(k,n)＝FFT{Sr(t,n)}
In the formula, FFT { } represents a Fourier transform function, Sr(t, n) represents a magnetic resonance echo signal corresponding to the number n among the plurality of magnetic resonance echo signals, t represents time, n represents a unique number corresponding to the magnetic resonance echo signal, and k represents a discrete sampling point number in the fourier transform;
at all of the first magnetic resonance echo frequency spectrum Fr(k, n), selecting the magnetic resonance echo spectrum F corresponding to the ringing signal with the strongest signalr(k,Nr) Wherein N isrA unique number representing the ringing signal corresponding to the signal being strongest;
subjecting the magnetic resonance echo spectrum Fr(k,Nr) As a reference spectrum, for each of the first magnetic resonance echo spectra Fr(k, n) respectively carrying out normalization processing to obtain corresponding normalized magnetic resonance echo frequency spectrums H (k, n):
in the formula, gammak,nRepresenting the amplitude of the magnetic resonance echo signal corresponding to the number n at the kth discrete sampling point number, e representing the base of the natural logarithm, j representing the complex number, ωnRepresents the phase change rate of the magnetic resonance echo signal corresponding to the number n;
carrying out phase difference on the normalized magnetic resonance echo frequency spectrum H (k, n) according to the following formula to obtain a phase difference component delta H (k, n) of the numbers of two adjacent discrete sampling points:
in the formula, H*(k +1, n) represents the conjugate function corresponding to H (k +1, n), H (k +1, n) represents the normalized magnetic resonance echo spectrum of the magnetic resonance echo signal corresponding to the number n at the (k + 1) th discrete sampling point number, γk+1,nRepresents the amplitude of the magnetic resonance echo signal corresponding to the number n at the (k + 1) th discrete sampling point numberA value;
all the phase difference components Delta H (k, n) are summed, and the total phase difference quantity Delta phi is calculated0(n)：
In the formula (I), the compound is shown in the specification,
representing the amplitude estimate of the magnetic resonance echo signal corresponding to the number n,
a phase change rate estimation value representing the magnetic resonance echo signal corresponding to the number n;
from the normalized magnetic resonance echo spectrum H (k, n) and the phase difference sum delta phi0(n) calculating the initial phase delta phi of the compensation phase according to the following formula1(n)：
Where K denotes the total number of discrete sampling points, θ, in a magnetic resonance echo signalnAn initial phase representing the magnetic resonance echo signal corresponding to the number n and compensating the phase;
for each of the plurality of magnetic resonance echo signals, a corresponding compensation phase φ (k, n) is calculated according to the following formula:
4. the phase correction method according to claim 1, wherein performing phase compensation for each of the plurality of magnetic resonance echo signals that is not a ringing signal according to a corresponding compensation phase to obtain a phase-corrected magnetic resonance echo signal comprises:
respectively carrying out Fourier transform on each magnetic resonance echo signal which is not a ringing signal in the plurality of magnetic resonance echo signals to obtain a corresponding second magnetic resonance echo frequency spectrum Fa(k,n)：
Fa(k,n)＝FFT{Sa(t,n)}
In the formula, FFT { } represents a Fourier transform function, Sa(t, n) represents a magnetic resonance echo signal corresponding to the number n among the plurality of magnetic resonance echo signals, t represents time, n represents a unique number corresponding to the magnetic resonance echo signal, and k represents a discrete sampling point number in the fourier transform;
aiming at each magnetic resonance echo signal which is not a ringing signal in the plurality of magnetic resonance echo signals, calculating to obtain a corresponding frequency spectrum F after phase compensation according to the following formulac(k,n)：
Fc(k,n)＝Fa(k,n)φ(k,n)
In the formula, phi (k, n) represents the compensation phase of the magnetic resonance echo signal corresponding to the number n;
for each magnetic resonance echo signal which is not a ringing signal in the plurality of magnetic resonance echo signals, corresponding frequency spectrum F after phase compensation is performedcAnd (k, n) performing inverse Fourier transform to obtain a phase-corrected magnetic resonance echo signal.
5. A phase correction device of a magnetic resonance echo signal is characterized by comprising a signal acquisition unit, a phase estimation unit and a phase compensation unit which are sequentially in communication connection;
the signal acquisition unit is used for acquiring a plurality of magnetic resonance echo signals which are discrete in a time domain, wherein at least one ringing signal exists in the plurality of magnetic resonance echo signals;
the phase estimation unit is configured to estimate a compensation phase of each of the plurality of magnetic resonance echo signals by using a ringing signal with a strongest signal among the at least one ringing signal as a reference signal;
and the phase compensation unit is used for performing phase compensation on each magnetic resonance echo signal which is a non-ringing signal in the plurality of magnetic resonance echo signals according to the corresponding compensation phase to obtain a phase-corrected magnetic resonance echo signal.
6. The phase correction device according to claim 5, wherein the signal acquisition unit comprises an acquisition window opening subunit and an acquisition window maintaining subunit which are in communication connection;
the acquisition window opening subunit is used for immediately opening the magnetic resonance acquisition window after the magnetic resonance emission window is finished;
and the acquisition window maintaining subunit is used for maintaining the magnetic resonance acquisition window, and acquiring discrete magnetic resonance echo signals in a time domain through the magnetic resonance acquisition window until normal acquisition work is completed.
7. The phase correction device as claimed in claim 5, wherein the phase estimation unit comprises a first fourier transform subunit, an echo spectrum selection subunit, a normalization processing subunit, a phase difference summation subunit, an initial phase calculation subunit and a compensation phase calculation subunit which are sequentially connected in communication;
the first fourier transform subunit is configured to perform fourier transform on each of the multiple magnetic resonance echo signals to obtain a corresponding first magnetic resonance echo frequency spectrum Fr(k,n)：
Fr(k,n)＝FFT{Sr(t,n)}
In the formula, FFT { } represents a Fourier transform function, Sr(t, n) represents a magnetic resonance echo signal corresponding to the number n among the plurality of magnetic resonance echo signals, t represents time, n represents a unique number corresponding to the magnetic resonance echo signal, and k represents a discrete sampling point number in the fourier transform;
the echo spectrum selection subunit is used for selecting all the first magnetic resonance echo spectrums Fr(k, n), selecting the ringing signal with the strongest signalNumber-corresponding magnetic resonance echo spectrum Fr(k,Nr) Wherein N isrA unique number representing the ringing signal corresponding to the signal being strongest;
the normalization processing subunit is used for converting the magnetic resonance echo frequency spectrum Fr(k,Nr) As a reference spectrum, for each of the first magnetic resonance echo spectra Fr(k, n) respectively carrying out normalization processing to obtain corresponding normalized magnetic resonance echo frequency spectrums H (k, n):
in the formula, gammak,nRepresenting the amplitude of the magnetic resonance echo signal corresponding to the number n at the kth discrete sampling point number, e representing the base of the natural logarithm, j representing the complex number, ωnRepresents the phase change rate of the magnetic resonance echo signal corresponding to the number n;
the phase difference processing subunit is configured to perform phase difference on the normalized magnetic resonance echo spectrum H (k, n) according to the following formula to obtain a phase difference component Δ H (k, n) between two adjacent discrete sampling points:
in the formula, H*(k +1, n) represents the conjugate function corresponding to H (k +1, n), H (k +1, n) represents the normalized magnetic resonance echo spectrum of the magnetic resonance echo signal corresponding to the number n at the (k + 1) th discrete sampling point number, γk+1,nRepresenting the amplitude of the magnetic resonance echo signal corresponding to the number n on the (k + 1) th discrete sampling point number;
the phase difference summation subunit is configured to sum all the phase difference components Δ H (k, n) to obtain a total phase difference amount Δ Φ0(n)：
In the formula (I), the compound is shown in the specification,
representing the amplitude estimate of the magnetic resonance echo signal corresponding to the number n,
a phase change rate estimation value representing the magnetic resonance echo signal corresponding to the number n;
the initial phase calculating subunit calculates the initial phase difference according to the normalized magnetic resonance echo spectrum H (k, n) and the phase difference total amount delta phi0(n) calculating the initial phase delta phi of the compensation phase according to the following formula1(n)：
Where K denotes the total number of discrete sampling points, θ, in a magnetic resonance echo signalnAn initial phase representing the magnetic resonance echo signal corresponding to the number n and compensating the phase;
the compensation phase calculation subunit is configured to calculate, for each of the plurality of magnetic resonance echo signals, a corresponding compensation phase Φ (k, n) according to the following formula:
8. the phase correction device as claimed in claim 5, wherein the phase compensation unit comprises a second fourier transform subunit, an echo spectrum compensation subunit and an inverse fourier transform subunit which are sequentially connected in communication;
the second fourier transform subunit is configured to perform fourier transform on each magnetic resonance echo signal that is not a ringing signal in the plurality of magnetic resonance echo signals, to obtain a corresponding second magnetic resonance echo frequency spectrum Fa(k,n)：
Fa(k,n)＝FFT{Sa(t,n)}
In the formula, FFT { } represents a Fourier transform function, Sa(t, n) represents a magnetic resonance echo signal corresponding to the number n among the plurality of magnetic resonance echo signals, t represents time, n represents a unique number corresponding to the magnetic resonance echo signal, and k represents a discrete sampling point number in the fourier transform;
the echo spectrum compensation subunit is configured to calculate, for each magnetic resonance echo signal that is not a ringing signal among the multiple magnetic resonance echo signals, a corresponding spectrum F after phase compensation according to the following formulac(k,n)：
Fc(k,n)＝Fa(k,n)φ(k,n)
In the formula, phi (k, n) represents the compensation phase of the magnetic resonance echo signal corresponding to the number n;
the inverse fourier transform subunit is configured to, for each magnetic resonance echo signal that is not a ringing signal in the plurality of magnetic resonance echo signals, apply the corresponding frequency spectrum F after phase compensationcAnd (k, n) performing inverse Fourier transform to obtain a phase-corrected magnetic resonance echo signal.
9. A computer device comprising a memory and a processor communicatively coupled, wherein the memory is configured to store a computer program and the processor is configured to read the computer program and execute the phase correction method according to any one of claims 1 to 4.
10. A computer-readable storage medium having instructions stored thereon, which when executed on a computer perform a method of phase correction as claimed in any one of claims 1 to 4.
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