Interference Cancellation Method, Medium and Electronic Device

Abstract

The present application relates to the technical field of signal processing, and discloses an interference cancellation method, medium and device. The method includes: a first application step of applying a radio frequency pulse, applying a slice selection gradient at the same time, and then applying a slice rephasing gradient, a phase encoding gradient and a pre-applied phase gradient; a first acquisition step of applying a readout gradient and performing data acquisition at the same time to obtain an imaging echo; a second application step of applying a phase unwrapping gradient and the pre-applied phase gradient; a second acquisition step of applying the readout gradient and performing data acquisition at the same time to obtain a navigation echo; a filling step of filling an unfilled k-space line in the k-space with the imaging echo and returning to the first acquisition step until all the k-space lines in the k-space are filled, so as to obtain a plurality of imaging echoes and a plurality of navigation echoes; an image reconstruction step of generating a set of imaging echo data of each corrected imaging echo based on the plurality of imaging echoes and the plurality of navigation echoes for image reconstruction. The present invention can eliminate the influence of magnetic field perturbation on magnetic resonance imaging based on the plurality of acquired imaging echoes and the plurality of navigation echoes.

Description

Technical Field

[0001] This application relates to the field of signal processing technology, and particularly to an interference cancellation method, medium and electronic device for magnetic resonance imaging. Background Art

[0002] Rail transit (subway, train, etc.) or high-power electrical appliances near this magnetic resonance imaging system can cause changes in the magnetic field strength and direction in the imaging area. When there is magnetic field perturbation, the magnetic resonance signals received by the receiving coil will change in phase accordingly, resulting in inconsistent data phases between different phase-encoding lines (k-space lines) in the entire k-space, and further leading to image artifacts. This phenomenon is particularly obvious in low-field or ultra-low-field systems with relatively low main magnetic field strength. In addition, in clinical applications, patient movement (such as breathing, swallowing movements, etc.) can also cause magnetic field perturbation.

[0003] In order to eliminate the influence of magnetic field perturbation, a fluxgate sensor can be used to detect the magnetic field perturbation and drive an active shielding coil to cancel the influence of the perturbation, but this solution is costly. Summary of the Invention

[0004] Embodiments of this application provide an interference cancellation method, device, medium and equipment.

[0005] In a first aspect, embodiments of this application provide an interference cancellation method, which uses a gradient echo sequence to obtain a plurality of imaging echoes and a plurality of navigation echoes. The method includes: a first application step of applying a radio frequency pulse, simultaneously applying a slice selection gradient, then applying a slice rephasing gradient, a phase encoding gradient and a pre-phase gradient; a first acquisition step of applying a readout gradient and simultaneously performing data acquisition to obtain an imaging echo; a second application step of applying a phase unwrapping gradient and the pre-phase gradient after obtaining the imaging echo; a second acquisition step of applying the readout gradient and simultaneously performing data acquisition to obtain a navigation echo; a filling step of filling an unfilled k-space line in the k-space with the imaging echo and returning to the first acquisition step until all k-space lines in the k-space are filled, thereby obtaining the plurality of imaging echoes and the plurality of navigation echoes; an image reconstruction step of generating a set of imaging echo data for each corrected imaging echo according to the plurality of imaging echoes and the plurality of navigation echoes for image reconstruction.

[0006] In a possible implementation of the first aspect above, generating a set of imaging echo data for each corrected imaging echo based on the plurality of imaging echoes and the plurality of navigation echoes includes: sampling each navigation echo in the plurality of navigation echoes at a plurality of sampling points to obtain a set of navigation echo data for each navigation echo, and sampling each imaging echo in the plurality of imaging echoes at the plurality of sampling points to obtain a set of imaging echo data for each imaging echo; generating a set of imaging echo data for each corrected imaging echo based on the set of navigation echo data for each navigation echo and the set of imaging echo data for each imaging echo.

[0007] In a possible implementation of the first aspect above, for each navigation echo, selecting one navigation echo data from the set of navigation echo data as a reference navigation echo data, calculating an average phase difference of the set of navigation echo data relative to the reference navigation echo data at the plurality of sampling points; performing filtering processing on the average phase differences of the plurality of navigation echoes; obtaining an estimated phase change of the corresponding imaging echo in the plurality of imaging echoes at the plurality of sampling points based on the filtered average phase differences; generating a set of imaging echo data for each corrected imaging echo according to the estimated phase change.

[0008] In a possible implementation of the first aspect above, the phase difference ΔФ est (t) of the navigation echo data relative to the reference navigation echo data at the plurality of sampling points is obtained according to the following formula 1

[0009] ΔФ est (t) = angle(S nav (t) × conj(S ref (t))) Formula 1

[0010] where S nav (t) is the set of navigation echo data at the sampling point t, S ref (t) is the reference navigation echo data at the sampling point t, and the sampling point t is relative to the time when the radio frequency pulse is applied.

[0011] The weight w(t) of the phase difference ΔФ est (t) is obtained according to the following formula 2

[0012] w(t) = abs(S nav (t) × conj(S ref (t))) Formula 2

[0013] The average phase difference Ф0 of each navigation echo at the plurality of sampling points is obtained according to the following formula 3

[0014]

[0015] Among them, TE’ is the echo time of each navigation echo.

[0016] In a possible implementation of the above first aspect, filtering is performed on the average phase difference Φ0 of each of the plurality of navigation echoes to obtain the filtered average phase difference Φ’0 of each navigation echo.

[0017] And the phase change estimation ΔΦ‘ est (t) is obtained according to the following formula 4.

[0018]

[0019] In a possible implementation of the above first aspect, a set of imaging echo data S′ img (t) of each corrected imaging echo is generated according to the following formula 5.

[0020]

[0021] Among them, S img (t) is a set of imaging echo data obtained by sampling each imaging echo at the sampling point t.

[0022] In a possible implementation of the above first aspect, before the first acquisition step, a radio frequency pulse is applied, and at the same time a slice selection gradient is applied, and then a slice selection refocusing gradient, a phase encoding gradient, and a pre - applied phase gradient are applied.

[0023] In a possible implementation of the above first aspect, the filtering process is weighted average filtering or Kalman filtering.

[0024] In a possible implementation of the above first aspect, the gradient echo sequence is composed of a radio frequency pulse, a slice selection gradient, a slice selection refocusing gradient, a phase encoding gradient, the pre - applied phase gradient, a readout gradient, and a phase rewinder gradient.

[0025] Second aspect, embodiments of the present application provide an interference cancellation device, which uses a gradient echo sequence to obtain a plurality of imaging echoes and a plurality of navigation echoes. The device includes: a first application module that applies a radio frequency pulse, simultaneously applies a slice selection gradient, then applies a slice selection rephasing gradient, a phase encoding gradient, and a pre - applied phase gradient; a first acquisition module that applies a readout gradient and simultaneously performs data acquisition to obtain imaging echoes; a second application module that, after obtaining the imaging echoes, applies a phase unwrapping gradient and the pre - applied phase gradient; a second acquisition module that applies the readout gradient and simultaneously performs data acquisition to obtain navigation echoes; a filling module that fills an unfilled k - space line in k - space with the imaging echoes and returns to the first application module until all k - space lines in k - space are filled, thereby obtaining the plurality of imaging echoes and the plurality of navigation echoes; an image reconstruction module that generates a set of imaging echo data for each corrected imaging echo based on the plurality of imaging echoes and the plurality of navigation echoes for image reconstruction. For example, the above - mentioned first application module, first acquisition module, second application module, second acquisition module, filling module, and image reconstruction module can be implemented by a processor in an electronic device having the functions of these modules or units.

[0026] Third aspect, embodiments of the present application provide a computer - readable storage medium, on which instructions are stored. When the instructions are executed on a computer, the computer is caused to execute the interference cancellation method in the first aspect above.

[0027] Fourth aspect, embodiments of the present application provide an electronic device, including: one or more processors; one or more memories; the one or more memories store one or more programs. When the one or more programs are executed by the one or more processors, the electronic device is caused to execute the interference cancellation method in the first aspect above. Description of the Drawings

[0028] Figure 1 According to some embodiments of the present application, a schematic structural diagram of a magnetic resonance imaging device is shown;

[0029] Figure 2 According to some embodiments of the present application, a schematic flowchart of an interference cancellation method is shown;

[0030] Figure 3 According to some embodiments of the present application, a timing diagram of a gradient echo sequence is shown;

[0031] Figure 4 It shows a schematic diagram of k - space lines in k - space after filtering processing and the phase difference before and after filtering according to some embodiments;

[0032] Figure 5According to some embodiments of the present application, a block diagram of a computer of a magnetic resonance imaging device is shown. Detailed implementation manners

[0033] Illustrative embodiments of the present application include, but are not limited to, interference cancellation methods, devices, media, and apparatuses for magnetic resonance imaging.

[0034] The interference cancellation method provided by the embodiments of the present application can be applied to magnetic resonance imaging (MRI), but is not limited thereto.

[0035] As an example, in a magnetic resonance imaging scenario, an electronic device can be a device with magnetic resonance imaging function, which will be referred to as a magnetic resonance imaging device herein.

[0036] In the following embodiments, the interference cancellation method provided by the embodiments of the present application will be described mainly by taking the magnetic resonance imaging device in the magnetic resonance imaging scenario as an example to execute the interference cancellation method. Similarly, the implementation details of the electronic device executing the interference cancellation method in other application scenarios will not be elaborated one by one herein, and some descriptions can refer to the related descriptions of the magnetic resonance imaging device executing the interference cancellation method.

[0037] Magnetic resonance imaging technology can generate medical images in medical or clinical application scenarios for disease diagnosis. Specifically, magnetic resonance imaging technology can use the signals generated by the resonance of atomic nuclei in a strong magnetic field for image reconstruction to make tomographic images of cross-sections, sagittal planes, coronal planes, and various oblique planes of an object such as a human body.

[0038] In the implementation of the present application, the magnetic resonance imaging device can be a low-field or ultra-low-field magnetic resonance imaging device, or a mid-field or high-field magnetic resonance imaging device. As an example, magnetic resonance imaging systems in clinical applications can usually be classified into high-field (above 1T), mid-field (0.3 - 1T), low-field (0.1 - 0.3T), and ultra-low-field (below 0.1T) according to the magnetic field strength.

[0039] It can be understood that the embodiments of the present application are mainly applied to low-field or ultra-low-field magnetic resonance imaging devices to eliminate magnetic field perturbations during magnetic resonance imaging, thereby eliminating artifacts existing in magnetic resonance imaging and improving the quality of magnetic resonance imaging.

[0040] The embodiments of the present application will be further described in detail below with reference to the accompanying drawings.

[0041] As Figure 1As shown in the figure, it is a possible structural schematic diagram of a magnetic resonance imaging device provided by an embodiment of the present application. The magnetic resonance imaging device 100 may include: a computer 101, a spectrometer 102, a gradient amplifier 103, gradient coils 104, a transmit RF amplifier 105, a transmit RF coil (also referred to as a transmit coil) 106, a receive RF amplifier 107, a receive RF coil 108 (also referred to as a receive coil), and a magnet 109.

[0042] Specifically, the computer 101 is used to issue instructions to the spectrometer 102 under the control of an operator to trigger the spectrometer 102 to generate waveforms of gradient signals and waveforms of RF signals according to the instructions. After the gradient signals generated by the spectrometer 102 are amplified by the gradient amplifier 103, magnetic field gradients are formed by the gradient coils 104, thereby realizing spatial gradient encoding for magnetic resonance signals (specifically, magnetic resonance imaging signals). Specifically, spatial gradient encoding is used to spatially locate magnetic resonance signals, that is, to distinguish the positions where the magnetic resonance signals originate. The RF signals generated by the spectrometer 102 are amplified by the transmit RF amplifier 105 and transmitted by the transmit RF coil 106, thereby exciting protons (hydrogen nuclei) in the imaging region. Among them, the excited protons can emit RF signals, which can be received by the receive coil 108, amplified by the receive RF amplifier 107, and then converted into digital signals by the spectrometer 102, and further transmitted to the computer 101 for processing to obtain and display images. In addition, the magnet 109 can be any suitable type of magnet capable of generating a main magnetic field.

[0043] In some embodiments, the above-mentioned receive coil 108 can be implemented using a single or multiple phased array coils widely used in modern medical magnetic resonance imaging.

[0044] It can be understood that in the embodiments of the present application, the design and layout (deployment position, deployment direction, etc.) of the receive coil in the magnetic resonance imaging device 100 are not specifically limited and can be any implementable solution.

[0045] For gradient echo, the magnetic resonance signal received by the receive coil can be expressed as

[0046]

[0047] where S(t) is the magnetic resonance imaging signal received by the receive coil at time t, ρ is the proton spin distribution, γ is the gyromagnetic ratio, G is the field strength distribution at various locations within the Field of View (FOV), and x represents the spatial vector coordinate. If a subway or the like passes nearby, then magnetic field disturbances will be generated, and it can be considered that this disturbance is a constant within the entire field of view, that is

[0048] G′ x = G x + ΔG Equation (2)

[0049] Then Equation (1) can be rewritten as

[0050]

[0051] That is

[0052]

[0053] Therefore, the phase of the magnetic resonance signal will change, and the phase change can be expressed as

[0054] ΔФ(t) = -γΔGt Equation (5)

[0055] Based on the above description, the main workflow of the magnetic field perturbation interference cancellation method performed by the nuclear magnetic resonance imaging device 100 will be specifically introduced below. Specifically, the technical details described in the nuclear magnetic resonance imaging device 100 shown above are still applicable in the following method workflow. To avoid repetition, some will not be elaborated again. In some embodiments, the execution subject of the magnetic field perturbation interference cancellation method of the present application can be the nuclear magnetic resonance imaging device 100, specifically the computer 101 in the nuclear magnetic resonance imaging device 100. As Figure 1 shown, it is a schematic flowchart of an interference cancellation method provided by the present application. This method uses a gradient echo sequence to obtain a plurality of imaging echoes and a plurality of navigator echoes. Figure 2 shown is a timing diagram of the gradient echo sequence. In this embodiment, this method is used to eliminate the influence of magnetic field perturbation on nuclear magnetic resonance imaging. Figure 3 First application step 201: The nuclear magnetic resonance imaging device 100 applies a radio frequency pulse, applies a slice selection gradient at the same time, then applies a slice selection rephasing gradient, a phase encoding gradient, and a pre-applied phase gradient. Specifically, the nuclear magnetic resonance imaging device 100 applies a radio frequency pulse, applies a slice selection gradient at the same time, then applies a slice selection rephasing gradient, and applies a phase encoding gradient and a pre-applied phase gradient in the readout direction at the same time.

[0056] First acquisition step 202: The nuclear magnetic resonance imaging device 100 applies a readout gradient and performs data acquisition at the same time to obtain an imaging echo. Specifically, the magnetic resonance imaging signal received by the receive coil 108 is acquired to obtain an imaging echo.

[0057] Second application step 203: After obtaining the imaging echo, the nuclear magnetic resonance imaging device 100 applies a phase rewinder gradient and a pre-applied phase gradient.

[0058]

[0059] ​Specifically, after obtaining the imaging echo, the magnetic resonance imaging device 100 immediately applies a phase rewinder gradient in the phase encoding direction and a pre-phase gradient in the readout direction.

[0060] Second acquisition step 2034: The magnetic resonance imaging device 100 applies a readout gradient while performing data acquisition to obtain a navigation echo. Specifically, the magnetic resonance imaging signal received by the receiving coil 108 is acquired to obtain a navigation echo.

[0061] It can be understood that in the present invention, after each acquisition of an imaging echo, a navigation echo is acquired.

[0062] Filling step 205: The magnetic resonance imaging device 100 fills an unfilled k-space line in the k-space with the imaging echo and returns to step 201 until all the k-space lines in the k-space are filled, thereby obtaining a plurality of imaging echoes and a plurality of navigation echoes.

[0063] It can be understood that after acquiring an imaging echo and the corresponding navigation echo, an unfilled k-space line in the k-space is filled with this imaging echo. If there are still unfilled k-space lines in the k-space, then return to step 201 and repeat steps 201 - 205 until all the k-space lines in the k-space are filled. Thus, by repeating the above steps 201 - 205, a plurality of imaging echoes and a plurality of navigation echoes can be obtained. It can be understood that an imaging echo corresponds to a navigation echo.

[0064] Image reconstruction step 206, the magnetic resonance imaging device 100 generates a set of imaging echo data for each corrected imaging echo based on the above-mentioned plurality of imaging echoes and plurality of navigation echoes for image reconstruction.

[0065] Specifically, the magnetic resonance imaging device 100 samples each navigation echo among the plurality of navigation echoes at a plurality of sampling points to obtain a set of navigation echo data for each navigation echo, and samples each imaging echo among the plurality of imaging echoes at a plurality of sampling points to obtain a set of imaging echo data for each imaging echo.

[0066] For each navigation echo, a navigation echo data in a set of navigation echo data is selected as a reference navigation echo data. It can be understood that any one can be selected from a set of navigation echo data as the reference navigation echo data. Then, the average phase difference of a set of navigation echo data relative to the reference navigation echo data at a plurality of sampling points is calculated.

[0067] Specifically, for each navigation echo, the phase difference ΔФ of a set of navigation echo data relative to the reference navigation echo data at a plurality of sampling points is calculated according to the following formula 1 est (t).

[0068] ΔФ est (t) = angle(S nav (t) × conj(S ref (t))) Formula 1

[0069] Wherein, S nav (t) is a set of navigation echo data at sampling point t, and S ref (t) is the reference navigation echo data at sampling point t. angle is a function for calculating the phase angle, and conj is a function for calculating the conjugate complex number. Among them, the sampling point t is relative to the moment when the radio frequency pulse is applied. It can be understood that taking the application of the radio frequency pulse as the 0 moment, the sampling point t is the moment relative to the 0 moment.

[0070] Next, the phase difference ΔФ is obtained according to the following Formula 2 est (t) the weight w(t), that is, the weight for calculating the weighted average (t),

[0071] w(t) = abs(S nav (t) × conj(S ref (t))) Formula 2

[0072] Wherein abs is a function for calculating the amplitude.

[0073] The average phase difference Ф0 of each navigation echo at multiple sampling points is obtained according to the following Formula 3

[0074]

[0075] Wherein, TE’ is the echo time of each navigation echo.

[0076] In this way, the average phase difference Ф0 of each of the multiple navigation echoes is obtained. Next, other prior information can be introduced to reduce the influence of noise on the estimation accuracy of the phase difference. For example, it can be considered that the magnetic field perturbation is low-frequency. Then, in the order of acquisition time, the average phase difference Ф0 of each of the multiple navigation echoes is rearranged and filtered.

[0077] Specifically, the average phase difference Ф0 of each of the multiple navigation echoes is arranged according to the acquisition time of each navigation echo and filtered as a time series, so as to obtain the filtered average phase difference Φ’0 of each navigation echo.

[0078] In the embodiment of the present invention, the filtering process is a weighted average filtering process, a Kalman filter, or other filtering processes, without limitation.

[0079] The weighted average filtering can be expressed as:

[0080]

[0081] where ΔФ i is the phase change corresponding to the i-th k-space line sorted by acquisition time, and ΔФ′ n is the estimation of the phase change corresponding to the n-th k-space line after filtering, and w i is the weight for the i-th spatial line during weighted average filtering; here, the window width of the weighted average filtering is 2m + 1. Generally speaking, the closer i is to n, the greater the weight. For example, the weight can be defined according to the Gaussian function:

[0082]

[0083] The weighted average filtering that defines the weight according to this Gaussian function is the Gaussian filtering.

[0084] Figure 4 FIG. shows the schematic diagrams of the phase differences of each k-space line in k-space before and after filtering according to some embodiments, where the thin solid line is the estimation of the phase difference before filtering, and the thick dashed line is the estimation of the phase difference after filtering. It can be seen that through the above filtering process, the influence of noise can be reduced.

[0085] Next, based on the average phase difference Ф0 after the filtering process, the phase change estimations of the corresponding imaging echoes at multiple sampling points in multiple imaging echoes are obtained.

[0086] Specifically, the phase change estimation ΔΦ‘ est (t) is obtained according to the following formula 4

[0087]

[0088] Then, based on the above phase change estimations, a set of imaging echo data for each corrected imaging echo is generated.

[0089] Specifically, a set of imaging echo data S′ img (t) for each corrected imaging echo is generated according to the following formula 5

[0090]

[0091] where S img (t) is a set of imaging echo data obtained by sampling each imaging echo at the sampling point t. Here, i represents an imaginary number.

[0092] It can be understood that the gradient echo sequence consists of a radio frequency pulse, a slice selection gradient, a slice rephasing gradient, a phase encoding gradient, a pre-phase gradient, a readout gradient, a phase rewinding gradient, and a spoiling gradient.

[0093] It can be understood that the interference cancellation method provided in this application, after acquiring the imaging echo each time, then acquiring the navigation echo, has the following advantages: it can minimize the echo time of the imaging echo as much as possible, which is beneficial to improving the signal-to-noise ratio of the imaging echo data and obtaining better T1 contrast; it can maximize the echo time of the navigation echo as much as possible, which is beneficial to improving the sensitivity of its phase to magnetic field perturbations; using a phase rewinder gradient instead of a radio frequency pulse before acquiring the navigation echo is beneficial to improving the signal-to-noise ratio of the imaging echo data.

[0094] It can be understood that the present invention can eliminate the influence of magnetic field perturbations on magnetic resonance imaging, eliminate the artifacts existing in magnetic resonance imaging, and improve the quality of magnetic resonance imaging based on multiple acquired imaging echoes and multiple navigation echoes.

[0095] In addition, as can be seen from the above formula (5), the longer the echo time, the more significant the phase change caused by magnetic field perturbations. Therefore, the phase change caused by magnetic field perturbations can also be minimized by reducing TE.

[0096] If the magnetic resonance imaging system is in a non-electromagnetic shielding environment, it is necessary to first remove the influence of electromagnetic interference (refer to the previously filed patents "Interference Cancellation Method, Medium and Device", CN113176528A / CN113180636A / CN113203969A, which can be incorporated herein by reference), and then use the method proposed in the present invention to eliminate the influence of magnetic field perturbations.

[0097] Similarly, for other scenarios to which the embodiments of this application are applied, the electronic device can also implement the interference cancellation method according to steps similar to steps 201 - 205 above, except that the execution subject is different.

[0098] Now refer to Figure 5 , which shows a block diagram of a computer in a magnetic resonance imaging device 100 according to an embodiment of the present application. Figure 5 Schematically shown is an example computer 1400 according to multiple embodiments. In one embodiment, the system 1400 may include one or more processors 1404, system control logic 1408 connected to at least one of the processors 1404, system memory 1412 connected to the system control logic 1408, non-volatile memory (NVM) 1416 connected to the system control logic 1408, and a network interface 1420 connected to the system control logic 1408.

[0099] In some embodiments, the processor 1404 may include one or more single-core or multi-core processors. In some embodiments, the processor 1404 may include any combination of a general-purpose processor and a dedicated processor (e.g., a graphics processor, an application processor, a baseband processor, etc.). In embodiments where the system 1400 employs an eNB (Evolved Node B) 101 or a RAN (Radio Access Network) controller 102, the processor 1404 may be configured to execute various compliant embodiments, such as, for example, as Figure 2 shown in the embodiments.

[0100] In some embodiments, the system control logic 1408 may include any suitable interface controller to provide any suitable interface to at least one of the processors 1404 and / or any suitable device or component communicating with the system control logic 1408.

[0101] In some embodiments, the system control logic 1408 may include one or more memory controllers to provide an interface to the system memory 1412. The system memory 1412 may be used to load and store data and / or instructions. In some embodiments, the memory 1412 of the system 1400 may include any suitable volatile memory, such as a suitable dynamic random access memory (DRAM).

[0102] The NVM / memory 1416 may include one or more tangible, non-transitory computer-readable media for storing data and / or instructions. In some embodiments, the NVM / memory 1416 may include any suitable non-volatile memory such as flash memory and / or any suitable non-volatile storage device, such as at least one of a HDD (Hard Disk Drive), a CD (Compact Disc) drive, and a DVD (Digital Versatile Disc) drive.

[0103] The NVM / memory 1416 may include a portion of the storage resources on the device on which the system 1400 is installed, or it may be accessible by the device but not necessarily part of the device. For example, the NVM / memory 1416 may be accessed via the network interface 1420 over a network.

[0104] Specifically, the system memory 1412 and the NVM / memory 1416 may respectively include: a temporary copy and a permanent copy of the instructions 1424. The instructions 1424 may include: when executed by at least one of the processors 1404, cause the computer 1400 to implement as Figure 2Instructions of the method shown. In some embodiments, instructions 1424, hardware, firmware, and / or its software components may alternatively be placed in system control logic 1408, network interface 1420, and / or processor 1404.

[0105] Network interface 1420 may include a transceiver for providing a radio interface for system 1400, and thus communicating with any other suitable devices (such as front-end modules, antennas, etc.) via one or more networks. In some embodiments, network interface 1420 may be integrated with other components of system 1400. For example, network interface 1420 may be integrated in at least one of processor 1404, system memory 1412, NVM / memory 1416, and a firmware device with instructions (not shown), and when at least one of the instructions is executed by processor 1404, computer 1400 implements as Figure 2 the method shown.

[0106] Network interface 1420 may further include any suitable hardware and / or firmware to provide a multiple-input multiple-output radio interface. For example, network interface 1420 may be a network adapter, a wireless network adapter, a telephone modem, and / or a wireless modem.

[0107] In one embodiment, at least one of processors 1404 may be packaged together with the logic of one or more controllers for system control logic 1408 to form a system-in-package (SiP). In one embodiment, at least one of processors 1404 may be integrated with the logic of one or more controllers for system control logic 1408 on the same die to form a system-on-chip (SoC).

[0108] Computer 1400 may further include: input / output (I / O) device 1432. I / O device 1432 may include a user interface that enables a user to interact with computer 1400; the design of the peripheral component interface enables peripheral components to also interact with computer 1400. In some embodiments, computer 1400 further includes sensors for determining at least one of environmental conditions and location information related to computer 1400.

[0109] In some embodiments, the user interface may include, but is not limited to, a display (e.g., a liquid crystal display, a touch screen display, etc.), a speaker, a microphone, one or more cameras (e.g., a still image camera and / or a video camera), a flashlight (e.g., a light-emitting diode flash), and a keyboard. For example, the above user interface may be used to display imaging images of a magnetic resonance imaging process and images of k-space, etc.

[0110] Embodiments of the mechanisms disclosed in this application can be implemented in hardware, software, firmware, or combinations of these implementation methods. Embodiments of this application can be implemented as a computer program or program code executed on a programmable system, which includes at least one processor, a storage system (including volatile and non-volatile memories and / or storage elements), at least one input device, and at least one output device.

[0111] The program code can be applied to the input instructions to perform the various functions described in this application and generate output information. The output information can be applied to one or more output devices in a known manner. For the purposes of this application, a processing system includes any system having a processor such as, for example, a digital signal processor (DSP), a microcontroller, an application specific integrated circuit (ASIC), or a microprocessor.

[0112] The program code can be implemented in a high-level procedural language or an object-oriented programming language in order to communicate with the processing system. When needed, the program code can also be implemented in assembly language or machine language. In fact, the mechanisms described in this application are not limited to the scope of any particular programming language. In either case, the language can be a compiled language or an interpreted language.

[0113] In some cases, the disclosed embodiments can be implemented in hardware, firmware, software, or any combination thereof. The disclosed embodiments can also be implemented as instructions carried or stored on one or more transient or non-transient machine-readable (e.g., computer-readable) storage media, which can be read and executed by one or more processors. For example, the instructions can be distributed via a network or via other computer-readable media. Thus, a machine-readable medium can include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computer), including but not limited to, a floppy disk, a compact disc, an optical disc, a compact disc read-only memory (CD-ROM), a magneto-optical disc, a read-only memory (ROM), a random access memory (RAM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), a magnetic or optical card, a flash memory, or a tangible machine-readable memory for transmitting information (e.g., carrier waves, infrared signals, digital signals, etc.) in electrical, optical, acoustic, or other forms via the Internet. Thus, a machine-readable medium includes any type of machine-readable medium suitable for storing or transmitting electronic instructions or information in a form readable by a machine (e.g., a computer).

[0114] In the accompanying drawings, some structural or method features may be shown in a particular arrangement and / or order. However, it should be understood that such a particular arrangement and / or ordering may not be required. Instead, in some embodiments, these features may be arranged in a manner and / or order different from that shown in the illustrative drawings. Additionally, the inclusion of a structural or method feature in a particular figure does not imply that such a feature is required in all embodiments, and in some embodiments, these features may not be included or may be combined with other features.

[0115] It should be noted that each unit / module mentioned in the device embodiments of this application is a logical unit / module. Physically, a logical unit / module can be a physical unit / module, a part of a physical unit / module, or can be implemented as a combination of multiple physical units / module. The physical implementation manner of these logical units / modules themselves is not the most important. The combination of the functions implemented by these logical units / modules is the key to solving the technical problems proposed in this application. In addition, to highlight the innovative part of this application, the above device embodiments of this application do not introduce units / modules that are not closely related to solving the technical problems proposed in this application. This does not mean that there are no other units / modules in the above device embodiments.

[0116] It should be noted that in the examples and descriptions of this patent, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising one" does not exclude the presence of additional identical elements in the process, method, article or device comprising the element.

[0117] Although this application has been illustrated and described by reference to certain preferred embodiments thereof, those of ordinary skill in the art should understand that various changes in form and detail may be made thereto without departing from the spirit and scope of this application.

Claims

1. A method for interference cancellation, characterized in that, Obtaining a plurality of imaging echoes and a plurality of navigator echoes using a gradient echo sequence, the method comprising: A first application step of applying a radio frequency pulse while applying a slice selection gradient, then applying a slice selection rephasing gradient, a phase encoding gradient, and a pre-phase gradient; A first acquisition step of applying a readout gradient while performing data acquisition to obtain an imaging echo; A second application step of, after obtaining the imaging echo, applying a phase unwrapping gradient and the pre-phase gradient and not applying the radio frequency pulse; A second acquisition step of applying the readout gradient while performing data acquisition to obtain a navigator echo; A filling step of filling an unfilled k-space line in k-space with the imaging echo and returning to the first application step until all k-space lines in k-space are filled, thereby obtaining the plurality of imaging echoes and the plurality of navigator echoes; An image reconstruction step of generating a set of imaging echo data for each corrected imaging echo based on the plurality of imaging echoes and the plurality of navigator echoes for image reconstruction, wherein, for each navigator echo, one navigator echo data in a set of navigator echo data is selected as a reference navigator echo data, and an average phase difference at a plurality of sampling points of the set of navigator echo data relative to the reference navigator echo data is calculated; Performing a filtering process on the average phase difference of each of the plurality of navigator echoes; Based on the filtered average phase difference, obtaining an estimation of the phase change of the corresponding imaging echo among the plurality of imaging echoes at the plurality of sampling points; Generating a set of imaging echo data for each corrected imaging echo according to the phase change estimation, Among them, the phase difference ΔФ of the set of navigation echo data relative to the reference navigation echo data at the plurality of sampling points is obtained according to the following formula 1 est (t), ΔФ est (t) = angle(S nav (t) × conj(S ref (t))) Equation 1 where S nav (t) is the set of navigation echo data at the sampling point t, and S ref (t) is the reference navigation echo data at the sampling point t, and the sampling point t is relative to the time when the radio frequency pulse is applied The phase difference ΔФ is obtained according to the following formula 2 est The weight w(t) of (t), w(t) = abs(S nav (t) × conj(S ref (t))) Equation 2 Obtaining the average phase difference Ф0 of each navigator echo at the plurality of sampling points according to the following formula 3, where TE’ is the echo time of each navigator echo.

2. The method according to claim 1, wherein Generating a set of imaging echo data for each corrected imaging echo based on the plurality of imaging echoes and the plurality of navigator echoes includes: Sampling each of the plurality of navigator echoes at a plurality of sampling points to obtain a set of navigator echo data for each navigator echo, and sampling each of the plurality of imaging echoes at the plurality of sampling points to obtain a set of imaging echo data for each imaging echo; Generating a set of imaging echo data for each corrected imaging echo according to a set of navigator echo data of each navigator echo and a set of imaging echo data of each imaging echo.

3. The method according to claim 1, wherein Performing a filtering process on the average phase difference Φ0 of each of the plurality of navigator echoes to obtain a filtered average phase difference Φ’0 of each navigator echo, and obtain the estimated phase change ΔΦ' according to the following formula 4 est (t), 4. The method according to claim 3, wherein Generate a set of imaging echo data S′ of each corrected imaging echo according to the following formula 5 img (t), Among them, S img (t) is a set of imaging echo data obtained by sampling each imaging echo at the sampling point t.

5. The method according to claim 1, wherein Before the first acquisition step, a radio frequency pulse is applied while applying a slice selection gradient, then a slice selection rephasing gradient, a phase encoding gradient, and a pre-phase gradient are applied.

6. The method according to any one of claims 1-5, characterized in that, The filtering process is a weighted average filtering process or a Kalman filter.

7. The method according to claim 1, characterized in that The gradient echo sequence consists of a radio frequency pulse, a slice selection gradient, a slice selection rephasing gradient, a phase encoding gradient, the pre-phase gradient, a readout gradient, a phase unwrapping gradient, and a spoiling gradient.

8. A computer-readable storage medium, characterized in that, Instructions are stored on the storage medium, and when executed on a computer, the instructions cause the computer to execute the interference cancellation method according to any one of claims 1 to 7.

9. An electronic device, characterized in that, Comprising: One or more processors; One or more memories; the one or more memories store one or more programs, and when the one or more programs are executed by the one or more processors, the electronic device is caused to execute the interference cancellation method according to any one of claims 1 to 7.

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