CN113721176A

CN113721176A - Interference cancellation method, medium, and electronic device

Info

Publication number: CN113721176A
Application number: CN202111011541.0A
Authority: CN
Inventors: 刘懿龙; 朱瑞星
Original assignee: Hangzhou Weiying Medical Technology Co ltd
Current assignee: Hangzhou Weiying Medical Technology Co ltd
Priority date: 2021-08-31
Filing date: 2021-08-31
Publication date: 2021-11-30

Abstract

The application relates to the technical field of signal processing, and discloses an interference elimination method, medium and equipment. The method comprises the following steps: a first application step of applying a radio frequency pulse while applying a slice selection gradient, and then applying a slice selection echo gradient, a phase encoding gradient and a pre-application phase gradient; a first acquisition step, applying a reading gradient and simultaneously acquiring data to obtain an imaging echo; a second applying step of applying a phase wrap-around gradient and the pre-applied phase gradient; a second acquisition step, applying the readout gradient and simultaneously acquiring data to obtain a navigation echo; a filling step, filling an unfilled k-space line in k-space with imaging echoes, and returning to the first acquisition step until all k-space lines in k-space are filled, thereby obtaining a plurality of imaging echoes and a plurality of navigation echoes; and an image reconstruction step, wherein a set of imaging echo data of each imaging echo after correction is generated according to the plurality of imaging echoes and the plurality of navigation echoes and is used for image reconstruction. The invention can eliminate the influence of magnetic field disturbance on magnetic resonance imaging based on a plurality of acquired imaging echoes and a plurality of acquired navigation echoes.

Description

Interference cancellation method, medium, and electronic device

Technical Field

The present disclosure relates to the field of signal processing technologies, and in particular, to an interference cancellation method, medium, and electronic device for magnetic resonance imaging.

Background

The magnetic field intensity and direction of an imaging area can be changed due to rail traffic (subway, train, etc.) or high-power electric appliances near the magnetic resonance imaging system. In the presence of magnetic field disturbances, the magnetic resonance signals received by the receiving coils are subject to phase changes, so that the data phases of different phase-encoded lines (k-space lines) in the entire k-space are inconsistent, thereby causing image artifacts. This phenomenon is particularly evident in low-field or ultra-low field systems where the main magnetic field strength is low. Furthermore, in clinical applications, patient motion (such as breathing, swallowing, etc.) can also cause magnetic field perturbations.

To eliminate the effect of the magnetic field disturbance, a fluxgate sensor may be used to detect the magnetic field disturbance and drive an active shield coil to counteract the effect of the disturbance, but this solution is costly.

Disclosure of Invention

The embodiment of the application provides an interference elimination method, an interference elimination device, a medium and equipment.

In a first aspect, an embodiment of the present application provides an interference cancellation method for obtaining multiple imaging echoes and multiple navigator echoes by using a gradient echo sequence, where the method includes: a first application step of applying a radio frequency pulse while applying a slice selection gradient, and then applying a slice selection echo gradient, a phase encoding gradient and a pre-application phase gradient; a first acquisition step, applying a reading gradient and simultaneously acquiring data to obtain an imaging echo; a second applying step of applying a phase wrap-around gradient and the pre-applied phase gradient after obtaining the imaging echo; a second acquisition step, applying the readout gradient and simultaneously acquiring data to obtain a navigation echo; a filling step of filling an unfilled k-space line in k-space with the imaging echoes and returning to the first acquisition step until all k-space lines in k-space are filled, thereby obtaining the plurality of imaging echoes and the plurality of navigator echoes; and an image reconstruction step of generating a set of imaging echo data of each imaging echo after correction according to the plurality of imaging echoes and the plurality of navigation echoes for image reconstruction.

In one possible implementation of the first aspect, generating a set of imaging echo data of each corrected imaging echo according to 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 resulting in 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 resulting in a set of imaging echo data for each imaging echo; and generating a set of imaging echo data of each imaging echo after correction according to the set of navigation echo data of each navigation echo and the set of imaging echo data of each imaging echo.

In a possible implementation of the first aspect, for each navigator echo, one navigator echo data in the set of navigator echo data is selected as a reference navigator echo data, and a phase difference average value of the set of navigator echo data relative to the reference navigator echo data at the plurality of sampling points is calculated; filtering the average value of the phase difference of each of the plurality of navigation echoes; obtaining phase change estimation of corresponding imaging echoes in the plurality of imaging echoes at the plurality of sampling points based on the phase difference average value after filtering processing; generating a set of imaging echo data for each of the corrected imaging echoes according to the phase change estimate.

In a possible implementation of the first aspect, the phase difference Δ Φ between the navigation echo data and 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))) formula 1

Wherein S is_nav(t) is the set of navigator echo data at sample point t, S_ref(t) is the reference navigation at the sampling point tEcho data, the sampling points t being relative to the time of application of the radio frequency pulse,

obtaining the phase difference delta phi according to the following formula 2_est(t) weight w (t),

w(t)＝abs(S_nav(t)×conj(S_ref(t))) formula 2

Obtaining the phase difference average value phi of each navigation echo at the plurality of sampling points according to the following formula 3₀，

Where TE' is the echo time of each navigator echo.

In a possible implementation of the first aspect, the average value of phase differences Φ for each of the plurality of navigator echoes is determined₀Filtering to obtain the filtered phase difference average value phi 'of each navigation echo'₀，

And obtaining the phase change estimation delta phi 'according to the following formula 4'_est(t)，

In one possible implementation of the first aspect, the corrected set of imaging echo data S 'of each imaging echo is generated according to the following formula 5'_img(t)，

Wherein S is_img(t) is a set of imaging echo data obtained by sampling each imaging echo at the sampling point t.

In a possible implementation of the first aspect described above, the first acquisition step is preceded by applying a radio frequency pulse while applying a slice selection gradient, and then by applying a slice selection echo gradient, a phase encoding gradient and a pre-applied phase gradient.

In one possible implementation of the first aspect described above, the filtering process is a weighted average filtering process or a kalman filter.

In one possible implementation of the first aspect, the gradient echo sequence is composed of a radio frequency pulse, a slice selection gradient, a slice selection echo gradient, a phase encoding gradient, the pre-applied phase gradient, a readout gradient, and a phase rewind gradient.

In a second aspect, an embodiment of the present application provides an interference cancellation apparatus for obtaining a plurality of imaging echoes and a plurality of navigator echoes by using a gradient echo sequence, where the apparatus includes: the first applying module applies radio frequency pulse, applies selective layer gradient at the same time, and then applies selective layer echo gradient, phase coding gradient and pre-applied phase gradient; the first acquisition module applies a reading gradient and simultaneously acquires data to obtain an imaging echo; a second applying module for applying a phase wrap-around gradient and the pre-applied phase gradient after obtaining the imaging echo; the second acquisition module applies the reading gradient and simultaneously performs data acquisition to obtain a navigation echo; a filling module for filling an unfilled k-space line in k-space with the imaging echoes and returning to the first applying module until all k-space lines in k-space are filled, thereby obtaining the plurality of imaging echoes and the plurality of navigator echoes; and the image reconstruction module generates a set of corrected imaging echo data of each imaging echo according to the plurality of imaging echoes and the plurality of navigation echoes for image reconstruction. For example, the first applying module, the first acquiring module, the second applying module, the second acquiring module, the filling module and the image reconstructing module may be implemented by a processor having functions of these modules or units in an electronic device.

In a third aspect, an embodiment of the present application provides a computer-readable storage medium, where instructions are stored on the storage medium, and when executed on a computer, the instructions cause the computer to perform the interference cancellation method in the first aspect.

In a fourth aspect, an embodiment of the present application provides an electronic device, including: one or more processors; one or more memories; the one or more memories store one or more programs that, when executed by the one or more processors, cause the electronic device to perform the interference cancellation method of the first aspect.

Drawings

Figure 1 shows a schematic structural diagram of a magnetic resonance imaging apparatus, according to some embodiments of the present application;

fig. 2 illustrates a flow diagram of a method of interference cancellation, according to some embodiments of the present application;

FIG. 3 illustrates a timing diagram of a gradient echo sequence, according to some embodiments of the present application;

FIG. 4 is a schematic diagram showing k-space lines and phase differences in k-space before and after filtering, according to some embodiments;

figure 5 illustrates a block diagram of a computer of a magnetic resonance imaging device, according to some embodiments of the present application.

Detailed Description

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

The interference cancellation method provided in the embodiment of the present application may be applied to Magnetic Resonance Imaging (MRI), but is not limited thereto.

As an example, in a magnetic resonance imaging scenario, the electronic device may be a device with magnetic resonance imaging functionality, which is referred to herein as a magnetic resonance imaging device.

In the following embodiments, an interference cancellation method performed by a magnetic resonance imaging device in a magnetic resonance imaging scene is mainly taken as an example, and the interference cancellation method provided by the embodiments of the present application is described. Similarly, details of implementation of the interference cancellation method performed by the electronic device in other application scenarios will not be repeated here, and some descriptions may refer to related descriptions of the interference cancellation method performed by the magnetic resonance imaging device.

Magnetic resonance imaging techniques can generate medical images in medical or clinical application scenarios for disease diagnosis. Specifically, the magnetic resonance imaging technique can perform image reconstruction using signals generated by the resonance of atomic nuclei in a strong magnetic field, and can generate tomographic images of a cross section, a sagittal plane, a coronal plane, and various inclined planes of a subject such as a human body.

In the implementation of the application, the magnetic resonance imaging equipment can be low-field and ultra-low-field magnetic resonance imaging equipment, and can also be medium-field and high-field magnetic resonance imaging equipment. As an example, magnetic resonance imaging systems in clinical applications can be generally classified by magnetic field strength into high field (above 1T), medium field (0.3-1T), low field (0.1-0.3T), and ultra-low field (below 0.1T).

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, and magnetic field disturbance is eliminated in the magnetic resonance imaging process, so that artifacts existing in the magnetic resonance imaging are eliminated, and the quality of the magnetic resonance imaging is improved.

Embodiments of the present application will be described in further detail below with reference to the accompanying drawings.

Fig. 1 is a schematic diagram of a possible structure of a magnetic resonance imaging apparatus provided in an embodiment of the present application. The magnetic resonance imaging apparatus 100 may include: computer 101, spectrometer 102, gradient amplifier 103, gradient coil 104, transmit radio frequency amplifier 105, transmit radio frequency coil (also referred to as transmit coil) 106, receive radio frequency amplifier 107, receive radio frequency coil 108 (also referred to as receive coil), and magnet 109.

Specifically, computer 101 is used to issue instructions to spectrometer 102 under the control of an operator to trigger spectrometer 102 to generate a waveform of a gradient signal and a waveform of a radio frequency signal according to the instructions. After the gradient signals generated by spectrometer 102 are amplified by gradient amplifier 103, gradient of the magnetic field is formed by gradient coil 104, so as to implement spatial gradient encoding for the magnetic resonance signals (specifically, magnetic resonance imaging signals). In particular, spatial gradient encoding is used to spatially localize the magnetic resonance signals, i.e. to distinguish the location of the source of the magnetic resonance signals. The radio frequency signals generated by spectrometer 102 are amplified by a transmission radio frequency amplifier 105 and transmitted by a transmission radio frequency coil 106, thereby exciting protons (hydrogen nuclei) in the imaging region. The excited protons may emit radio frequency signals, which may be received by the receiving coil 108, amplified by the receiving rf amplifier 107, converted into digital signals by the spectrometer 102, and transmitted to the computer 101 for processing, obtaining images, and displaying. Furthermore, the magnet 109 may be any suitable type of magnet capable of generating a main magnetic field.

In some embodiments, the receive coils 108 described above may be implemented using single or multiple phased array coils, which are widely used in modern medical magnetic resonance imaging.

It is to be understood that in the embodiment of the present application, the design and layout (deployment position, deployment direction, etc.) of the receiving coils in the magnetic resonance imaging apparatus 100 are not particularly limited, and may be any realizable scheme.

For gradient echoes, the magnetic resonance signals received by the receive coils can be expressed as

Wherein s (t) is a magnetic resonance imaging signal received by the receiving coil at time t, ρ is a proton spin distribution (spin distribution), γ is a gyromagnetic ratio (gyromagnetic ratio), G is a Field intensity distribution at each position in a Field of View (FOV), and x represents a space vector coordinate. If a subway or the like passes nearby, magnetic field disturbances will occur and can be considered as a constant over the entire field of view, i.e. the disturbance is constant

G′_x＝G_x+ Δ G formula (2)

Then formula (1) can be rewritten as

Namely, it is

Thus, the phase of the magnetic resonance signal will change, which can be expressed as

Equation (5) for Δ Φ (t) ═ γ Δ Gt

Based on the above description, the main workflow of the magnetic resonance imaging apparatus 100 to execute the magnetic field disturbance interference elimination method is described in detail below. In particular, the technical details described above for the magnetic resonance imaging apparatus 100 shown in fig. 1 are still applicable in the following method flow, and some details will not be described again to avoid repetition. In some embodiments, the subject of execution of the magnetic field disturbance rejection method of the present application may be the magnetic resonance imaging apparatus 100, in particular the computer 101 in the magnetic resonance imaging apparatus 100. Fig. 2 is a schematic flow chart of an interference cancellation method provided in the present application, which uses a gradient echo sequence to obtain a plurality of imaging echoes and a plurality of navigator echoes. Fig. 3 shows a timing diagram of a gradient echo sequence. In this embodiment, the method is used to eliminate the effect of magnetic field disturbance on magnetic resonance imaging.

First application step 201: the magnetic resonance imaging apparatus 100 applies radio frequency pulses while applying a slice selection gradient, then a slice selection echo gradient, a phase encoding gradient and a pre-applied phase gradient. Specifically, the magnetic resonance imaging apparatus 100 applies a radio frequency pulse while applying a slice selection gradient, and then applies a slice selection echo gradient while applying a phase encode gradient and a pre-applied phase gradient in a readout direction.

A first acquisition step 202: the magnetic resonance imaging apparatus 100 applies a readout gradient while data acquisition is performed, resulting in imaging echoes. Specifically, the magnetic resonance imaging signals received by the receiving coil 108 are acquired to obtain imaging echoes.

Second application step 203: after the imaging echoes are acquired, the magnetic resonance imaging apparatus 100 applies a phase wrap gradient and a pre-applied phase gradient.

Specifically, immediately after the imaging echo is obtained, the magnetic resonance imaging apparatus 100 applies a phase wrap-around gradient in the phase encoding direction and a pre-applied phase gradient in the readout direction.

Second acquisition step 2034: the magnetic resonance imaging apparatus 100 applies a readout gradient while performing data acquisition, resulting in navigator echoes. Specifically, the magnetic resonance imaging signals received by the receiving coil 108 are acquired to obtain the navigator echo.

It can be understood that in the present invention, after each acquisition of the imaging echo, the navigator echo is acquired.

A filling step 205: the magnetic resonance imaging apparatus 100 fills one unfilled k-space line in k-space with imaging echoes and returns to step 201 until the k-space line in k-space is filled, thereby obtaining a plurality of imaging echoes and a plurality of navigator echoes.

It will be appreciated that after the acquisition of the imaging echo and the corresponding navigator echo, an unfilled k-space line in k-space is filled with this imaging echo, and if there are still unfilled k-space lines in k-space, step 201 is returned to and step 201 and 205 is repeated until all k-space lines in k-space are filled. Thus, by repeating the

above step

201 and 205, a plurality of imaging echoes and a plurality of navigator echoes can be obtained. It will be appreciated that one imaging echo corresponds to one navigator echo.

An image reconstruction step 206, the magnetic resonance imaging apparatus 100 generates a set of imaging echo data of each corrected imaging echo according to the plurality of imaging echoes and the plurality of navigator echoes for image reconstruction.

Specifically, the magnetic resonance imaging apparatus 100 samples 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 samples each of the plurality of imaging echoes at a plurality of sampling points to obtain a set of imaging echo data for each imaging echo.

For each navigator echo, one navigator echo data of a set of navigator echo data is selected as reference navigator echo data. It will be appreciated that any one of a set of navigator echo data may be selected as the reference navigator echo data. Then, the average value of the phase differences of a group of navigation echo data relative to the reference navigation echo data at a plurality of sampling points is calculated.

Specifically, for each navigation echo, the phase difference Δ Φ of a group 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)。

ΔФ_est(t)＝angle(S_nav(t)×conj(S_ref(t))) formula 1

Wherein S is_nav(t) is a set of navigator echo data at sample point t, S_ref(t) is the reference navigator echo data at sample point t, angle is a function of the phase angle, and conj is a function of the complex conjugate. Where the sampling point t is relative to the time of application of the radio frequency pulse. It will be appreciated that with the application of the radio frequency pulse at time 0, the sampling point t is a time relative to time 0.

Then, the phase difference Δ Φ is obtained according to the following formula 2_est(t), i.e., the weight (t) of the weighted average,

w(t)＝abs(S_nav(t)×conj(S_ref(t))) formula 2

Where abs is a function of the amplitude.

Obtaining the phase difference average value phi of each navigation echo at a plurality of sampling points according to the following formula 3₀，

Where TE' is the echo time of each navigator echo.

Thus, the phase difference average value phi of each of the plurality of navigation echoes is obtained₀. Then, other a priori information may be introduced to reduce the influence of noise on the estimation accuracy of the phase difference. For example, if the magnetic field disturbance is considered to be low frequency, then the phase difference average Φ of each of the plurality of navigator echoes is determined in the order of acquisition time₀Rearranging and filtering.

Specifically, the phase difference average value Φ of each of the plurality of navigation echoes is₀Arranging according to the acquisition time of each navigation echo and using the time as the timeFiltering the sequence to obtain a filtered phase difference average value phi 'of each navigation echo'₀。

In the embodiment of the present invention, the filtering process is a weighted average filtering process, kalman filtering, or other filtering process, without limitation.

The weighted average filtering can be expressed as:

where Δ Φ_iIs the phase change corresponding to the ith k-space line sequenced according to the acquisition time, delta phi'_nFor the estimation of the phase change corresponding to the n-th k-space line after filtering, w_iThe weight of the corresponding ith space line in the weighted average filtering process is obtained; the window width of the weighted average filtering is here 2m + 1. In general, the closer i is to n, the higher the weight, for example, the weight can be defined according to a gaussian function:

the weighted average filtering with weights defined by this gaussian function is gaussian filtering.

Fig. 4 is a diagram showing phase differences for k-space lines in k-space before and after filtering, where the thin solid line is the estimate of the phase difference before filtering and the thick dashed line is the estimate of the phase difference after filtering, according to some embodiments. It can be seen that the influence of noise can be reduced by the above filtering process.

Next, based on the filtered phase difference average value Φ₀And obtaining phase change estimation of the corresponding imaging echo in the plurality of imaging echoes at the plurality of sampling points.

Specifically, the phase change estimate Δ Φ 'is obtained according to the following equation 4'_est(t)，

Then, a set of corrected imaging echo data for each imaging echo is generated based on the phase change estimation.

Specifically, a set of imaging echo data S 'for each corrected imaging echo is generated according to the following formula 5'_img(t)，

Wherein S is_img(t) is a set of imaging echo data obtained by sampling each imaging echo at sampling point t. Wherein i represents an imaginary number.

It is understood that the gradient echo sequence consists of a radio frequency pulse, a slice selection gradient, a slice selection echo gradient, a phase encoding gradient, a pre-applied phase gradient, a readout gradient, a phase wrap-around gradient, a destruction gradient.

It can be understood that, the interference cancellation method provided by the present application acquires the navigation echo after acquiring the imaging echo each time, and has the following advantages: the echo time of the imaging echo can be reduced as much as possible, which is beneficial to improving the signal-to-noise ratio of the imaging echo data and obtaining better T1 contrast; the echo time of the navigation echo can be increased as much as possible, and the sensitivity of the phase to magnetic field disturbance is favorably improved; phase rollback gradient is used instead of radio frequency pulse before navigation echo is collected, so that the signal to noise ratio of imaging echo data is improved.

It can be understood that the invention can eliminate the influence of magnetic field disturbance on magnetic resonance imaging, eliminate artifacts in magnetic resonance imaging and improve the quality of magnetic resonance imaging based on a plurality of acquired imaging echoes and a plurality of acquired navigation echoes.

Further, as is clear from the above equation (5), the phase change due to the magnetic field disturbance becomes more significant as the echo time becomes longer, and therefore, the phase change due to the magnetic field disturbance can be reduced as much as possible by reducing TE.

If the magnetic resonance imaging system is in a non-electromagnetic shielding environment, the influence of electromagnetic interference needs to be removed (refer to the filed patent "interference elimination method, medium and equipment", CN113176528A/CN113180636A/CN113203969A, which can be incorporated herein by reference), and then the method proposed by the present invention is used to eliminate the influence of magnetic field disturbance.

Similarly, for other scenarios applied in the embodiment of the present application, the electronic device may also implement the interference cancellation method according to steps similar to the aforementioned step 201 and step 205, except that the implementation subject is different.

Referring now to fig. 5, shown is a block diagram of a computer in a magnetic resonance imaging apparatus 100 in accordance with one embodiment of the present application. FIG. 5 schematically illustrates an example computer 1400 in accordance with various embodiments. In one embodiment, system 1400 may include one or more processors 1404, system control logic 1408 coupled to at least one of processors 1404, system memory 1412 coupled to system control logic 1408, non-volatile memory (NVM)1416 coupled to system control logic 1408, and a network interface 1420 coupled to system control logic 1408.

In some embodiments, processor 1404 may include one or more single-core or multi-core processors. In some embodiments, processor 1404 may include any combination of general-purpose processors and dedicated processors (e.g., graphics processors, application processors, baseband processors, etc.). In embodiments where system 1400 employs an eNB (enhanced Node B) 101 or RAN (Radio Access Network) controller 102, processor 1404 may be configured to perform various consistent embodiments, e.g., the embodiment shown in fig. 2.

In some embodiments, system control logic 1408 may include any suitable interface controllers to provide any suitable interface to at least one of processors 1404 and/or to any suitable device or component in communication with system control logic 1408.

In some embodiments, system control logic 1408 may include one or more memory controllers to provide an interface to system memory 1412. System memory 1412 may be used to load and store data and/or instructions. Memory 1412 of system 1400 may include any suitable volatile memory, such as suitable Dynamic Random Access Memory (DRAM), in some embodiments.

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), CD (Compact Disc) Drive, DVD (Digital Versatile Disc) Drive.

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

In particular, system memory 1412 and NVM/storage 1416 may each include: a temporary copy and a permanent copy of instructions 1424. Instructions 1424 may include: instructions that, when executed by at least one of the processors 1404, cause the computer 1400 to perform the method illustrated in fig. 2. In some embodiments, instructions 1424, hardware, firmware, and/or software components thereof may additionally/alternatively be located in system control logic 1408, network interface 1420, and/or processor 1404.

Network interface 1420 may include a transceiver to provide a radio interface for system 1400 to communicate with any other suitable device (e.g., front end module, antenna, etc.) over 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 with at least one of processor 1404, system memory 1412, NVM/storage 1416, and a firmware device (not shown) having instructions that, when executed by at least one of processors 1404, cause computer 1400 to implement the method shown in fig. 2.

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.

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

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

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., still image cameras and/or video cameras), a flashlight (e.g., a light emitting diode flash), and a keyboard. For example, the user interface described above may be used to display an imaging image of a magnetic resonance imaging procedure, an image of k-space, and the like.

Embodiments of the mechanisms disclosed herein may be implemented in hardware, software, firmware, or a combination of these implementations. Embodiments of the application may be implemented as computer programs or program code executing on programmable systems comprising at least one processor, a storage system (including volatile and non-volatile memory and/or storage elements), at least one input device, and at least one output device.

Program code may be applied to input instructions to perform the functions described herein and generate output information. The output information may be applied to one or more output devices in a known manner. For 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.

The program code may be implemented in a high level procedural or object oriented programming language to communicate with a processing system. The program code can also be implemented in assembly or machine language, if desired. Indeed, the mechanisms described in this application are not limited in scope to any particular programming language. In any case, the language may be a compiled or interpreted language.

In some cases, the disclosed embodiments may be implemented in hardware, firmware, software, or any combination thereof. The disclosed embodiments may also be implemented as instructions carried by or stored on one or more transitory or non-transitory machine-readable (e.g., computer-readable) storage media, which may be read and executed by one or more processors. For example, the instructions may be distributed via a network or via other computer readable media. Thus, a machine-readable medium may include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computer), including, but not limited to, floppy diskettes, optical disks, read-only memories (CD-ROMs), magneto-optical disks, read-only memories (ROMs), Random Access Memories (RAMs), erasable programmable read-only memories (EPROMs), electrically erasable programmable read-only memories (EEPROMs), magnetic or optical cards, flash memory, or a tangible machine-readable memory for transmitting information (e.g., carrier waves, infrared signal digital signals, etc.) using the internet in electrical, optical, acoustical or other forms of propagated signals. 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).

In the drawings, some features of the structures or methods may be shown in a particular arrangement and/or order. However, it is to be understood that such specific arrangement and/or ordering may not be required. Rather, in some embodiments, the features may be arranged in a manner and/or order different from that shown in the illustrative figures. In addition, the inclusion of a structural or methodical feature in a particular figure is not meant to imply that such feature is required in all embodiments, and in some embodiments, may not be included or may be combined with other features.

It should be noted that, in the embodiments of the apparatuses in the present application, each unit/module is a logical unit/module, and physically, one logical unit/module may be one physical unit/module, or may be a part of one physical unit/module, and may also be implemented by a combination of multiple physical units/modules, where the physical implementation manner of the logical unit/module itself is not the most important, and the combination of the functions implemented by the logical unit/module is the key to solve the technical problem provided by the present application. Furthermore, in order to highlight the innovative part of the present application, the above-mentioned device embodiments of the present application do not introduce units/modules which are not so closely related to solve the technical problems presented in the present application, which does not indicate that no other units/modules exist in the above-mentioned device embodiments.

It is noted that, in the examples and descriptions of this patent, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, the use of the verb "comprise a" to define an element does not exclude the presence of another, same element in a process, method, article, or apparatus that comprises the element.

While the present application has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present application.

Claims

1. An interference cancellation method for 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, and then applying a slice selection echo gradient, a phase encoding gradient and a pre-application phase gradient;

a first acquisition step, applying a reading gradient and simultaneously acquiring data to obtain an imaging echo;

a second applying step of applying a phase wrap-around gradient and the pre-applied phase gradient after obtaining the imaging echo;

a second acquisition step, applying the readout gradient and simultaneously acquiring data to obtain a navigation echo;

a filling step of filling an unfilled k-space line in k-space with the imaging echoes and returning to the first applying step until all k-space lines in k-space are filled, thereby obtaining the plurality of imaging echoes and the plurality of navigator echoes;

and an image reconstruction step of generating a set of imaging echo data of each imaging echo after correction according to the plurality of imaging echoes and the plurality of navigation echoes for image reconstruction.

2. The method of claim 1, wherein generating a set of imaging echo data for each imaging echo corrected for from the plurality of imaging echoes and the plurality of navigator echoes comprises:

sampling each of the plurality of navigator echoes at a plurality of sampling points resulting in 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 resulting in a set of imaging echo data for each imaging echo;

and generating a set of imaging echo data of each imaging echo after correction according to the set of navigation echo data of each navigation echo and the set of imaging echo data of each imaging echo.

3. The method of claim 2,

for each navigation echo, selecting one navigation echo data in the group of navigation echo data as reference navigation echo data, and calculating the average value of the phase difference of the group of navigation echo data relative to the reference navigation echo data at the plurality of sampling points;

filtering the average value of the phase difference of each of the plurality of navigation echoes;

obtaining phase change estimation of corresponding imaging echoes in the plurality of imaging echoes at the plurality of sampling points based on the phase difference average value after filtering processing;

generating a set of imaging echo data for each of the corrected imaging echoes according to the phase change estimate.

4. A method according to claim 3, wherein the phase difference Δ Φ between the set of navigator echo data and the reference navigator 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))) formula 1

Wherein S is_nav(t) is the set of navigator echo data at sample point t, S_ref(t) is the reference navigator echo data at the sampling point t, which is relative to the time instant at which the radio frequency pulse is applied,

w(t)＝abs(S_nav(t)×conj(S_ref(t))) formula 2

Where TE' is the echo time of each navigator echo.

5. Method according to claim 4, characterized in that the phase difference mean value Φ for each of the plurality of navigator echoes₀Filtering to obtain the filtered phase difference average value phi 'of each navigation echo'₀，

6. The method of claim 5, wherein the corrected set of imaging echo data S 'for each imaging echo is generated according to equation 5 below'_img(t)，

7. The method of claim 1,

prior to the first acquisition step, a radio frequency pulse is applied while applying a slice selection gradient, followed by a slice selection echo gradient, a phase encoding gradient and a pre-applied phase gradient.

8. The method according to any one of claims 3-7, wherein the filtering process is a weighted average filtering process or Kalman filtering.

9. The method of claim 1, wherein the gradient echo sequence consists of a radio frequency pulse, a slice selection gradient, a slice selection echo gradient, a phase encoding gradient, the pre-phasing gradient, a readout gradient, a phase wrap-around gradient, a destruction gradient.

10. A computer-readable storage medium having stored thereon instructions that, when executed on a computer, cause the computer to perform the interference cancellation method of any one of claims 1 to 9.

11. An electronic device, comprising: one or more processors; one or more memories; the one or more memories store one or more programs that, when executed by the one or more processors, cause the electronic device to perform the interference cancellation method of any of claims 1-9.