Systems and methods for simultaneous multi-layer multi-task imaging

Abstract

The present application provides a system for MRI. The system can acquire at least two auxiliary signals and at least two imaging signals by simultaneously applying an MRI pulse sequence to at least two slice positions of an object. For each of at least one target slice position among the at least two slice positions, the system can generate at least one target image of the target slice position based on the at least two auxiliary signals and the at least two imaging signals. During the application of the MRI pulse sequence, phase modulation can be applied to at least one of the at least two slice positions such that the at least two slice positions have different phases during the readout of at least one imaging signal.

Description

[0001] Cross-reference

[0002] This application claims priority to U.S. Application No. 17 / 246,545, filed on April 30, 2021, the entire content of which is incorporated herein by reference. Technical Field

[0003] This application is mainly related to magnetic resonance imaging (MRI), and more specifically, to an MRI system and method that combines simultaneous multi-slice imaging (SMS) technology and multi-tasking technology (also referred to as SMS multi-tasking imaging in this application). Background Art

[0004] Recently, SMS technology and multi-tasking technology have been used in MRI (magnetic resonance imaging). SMS technology allows for the simultaneous excitation of at least two slice positions of an object (e.g., a patient), which can accelerate the scanning process. However, the implementation of traditional SMS technology requires performing additional reference scans to obtain reference data for each slice position for slice separation, resulting in an increase in scanning time.

[0005] Multi-tasking technology can acquire multi-dimensional MRI data (e.g., information related to various physiological motions, relaxations, etc.) in a single MRI scan. However, traditional multi-tasking techniques need to separately acquire MRI data at different slice positions and can only utilize part of the MRI data for image reconstruction, with limited imaging efficiency. For example, multi-tasking technology is commonly used in cardiac scans for 2D T1 cine imaging, where MRI data needs to be separately acquired at each single-layer position of the object's heart. The MRI data at a single slice position can include at least two auxiliary signals, and the at least two auxiliary signals can be processed to resolve cardiac motion and respiratory motion. The cardiac scan time is long and the imaging efficiency is low. In typical short-axis cardiac imaging, due to significant contraction and relaxation in the middle and bottom of the heart, the auxiliary signals at the slice positions in the middle or bottom of the heart can provide relatively accurate motion information. However, due to the lack of obvious contraction and relaxation at the slice positions near the apex of the heart, the accuracy of the auxiliary signals at these slice positions is limited, and it is difficult to resolve the cardiac motion at these slice positions based on these auxiliary signals.

[0006] Therefore, it is desirable to provide systems and methods for SMS multi-tasking imaging that combine SMS technology and multi-tasking technology, thereby achieving the advantages of multi-tasking technology and SMS technology and solving the problems of these two technologies. Summary of the Invention

[0007] In order to combine the advantages of multi-tasking technology and SMS technology and solve the problems of these two technologies, this application provides the following technical solutions:

[0008] A method for MRI. The method includes acquiring at least two auxiliary signals and at least two imaging signals by simultaneously applying an MRI pulse sequence to at least two slice positions of an object; and for each of at least one target slice position among the at least two slice positions, generating at least one target image of the target slice position based on the at least two auxiliary signals and the at least two imaging signals. During the application of the MRI pulse sequence, phase modulation is applied to at least one of the at least two slice positions such that the at least two slice positions have different phases during the readout of at least one imaging signal.

[0009] In some embodiments, for each of at least one target slice position among the at least two slice positions, generating at least one target image of the target slice position includes: for each of at least one target slice position, determining at least one temporal basis function based on the at least two auxiliary signals, the at least one temporal basis function being related to at least one temporal variation dimension of the target slice position; determining at least one spatial basis function based on the at least one temporal basis function and the at least two imaging signals, the at least one spatial basis function being related to at least one spatial variation dimension of the target slice position; and generating the at least one target image of the target slice position based on the at least one temporal basis function and the at least one spatial basis function.

[0010] In some embodiments, determining at least one spatial basis function based on the at least one temporal basis function and the at least two imaging signals includes: constructing an optimization function related to the at least one spatial basis function, the optimization function including the at least two imaging signals and the at least one temporal basis function; and determining the at least one spatial basis function by solving the optimization function.

[0011] In some embodiments, the at least two auxiliary signals are related to at least one of cardiac motion, respiratory motion, T1 relaxation, T2 relaxation, chemical exchange saturation transfer, contrast agent dynamics, T1ρ contrast, molecular diffusion, or natural time.

[0012] In some embodiments, the at least two auxiliary signals correspond to the same k-space line in k-space.

[0013] In some embodiments, the at least two auxiliary signals and the at least two imaging signals are acquired by radial sampling, and the at least two auxiliary signals correspond to radial lines in k-space having a constant angle.

[0014] In some embodiments, the method of acquiring at least two auxiliary signals and at least two imaging signals is Cartesian sampling, and the at least two auxiliary signals correspond to Cartesian lines passing through the center of k-space in k-space.

[0015] In some embodiments, the phase modulation is applied to the at least one slice position such that the at least one slice position has a random phase during the readout of each imaging signal.

[0016] In some embodiments, the phase modulation is applied to the at least one slice position such that during the readout of successive imaging signals, the phase of the at least one slice position alternates between a first angle and a second angle, where the second angle is different from the first angle.

[0017] A system for MRI. The system includes an acquisition module and a generation module. The acquisition module is configured to obtain at least two auxiliary signals and at least two imaging signals collected by simultaneously applying an MRI pulse sequence to at least two slice positions of an object. The generation module is configured to generate at least one target image of each of at least one target slice position among the at least two slice positions based on the at least two auxiliary signals and the at least two imaging signals. During the application of the MRI pulse sequence, phase modulation is applied to at least one of the at least two slice positions such that the at least two slice positions have different phases during the readout of at least one imaging signal.

[0018] An apparatus for MRI. The apparatus includes at least one memory and at least one processor. The at least one memory is configured to store computer instructions, and the at least one processor is configured to execute at least some of the computer instructions to implement the method for MRI in this application.

[0019] Compared with traditional multi-tasking techniques, the SMS multi-tasking imaging technique of this application simultaneously images at least two slice positions, and thus has a higher scanning efficiency (e.g., reduced scanning time). In addition, the SMS multi-tasking imaging technique allows for the acquisition of auxiliary signals at at least two slice positions instead of a single slice position, which avoids the problem of limited accuracy of the auxiliary signals at the apical slice position and improves the data quality and the dynamic tracking effect based thereon. Compared with traditional SMS techniques, the SMS multi-tasking imaging technique disclosed herein applies the phase modulation for slice separation to the slice positions, thereby eliminating the need for an additional scan for generating a reference slice image and avoiding errors that may occur during the additional scan.

[0020] Additional features of the present application can be illustrated in the following description. By studying the following description and the corresponding drawings, or by understanding the production or operation of the embodiments, some additional features of the present application will be apparent to those skilled in the art. The features of the present application can be realized and obtained by practicing or using the methods, tools, and combinations listed in the detailed examples discussed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present application will be further described by way of exemplary embodiments. These exemplary embodiments will be described in detail with reference to the drawings. The drawings are not drawn to scale. These are non-limiting exemplary embodiments, in which the same reference numerals in the various figures represent similar structures, where:

[0022] Figure 1 is a schematic diagram of an exemplary MRI system according to some embodiments of the present application;

[0023] Figure 2 is a schematic diagram of an exemplary MRI scanner according to some embodiments of the present application;

[0024] Figure 3 is a schematic diagram of exemplary hardware and / or software components of a computing device according to some embodiments of the present application;

[0025] Figure 4 is a schematic diagram of exemplary hardware and / or software components of a mobile device according to some embodiments of the present application;

[0026] Figure 5 is a block diagram of an exemplary processing device according to some embodiments of the present application;

[0027] Figure 6 is a flowchart of an exemplary process for SMS multi-tasking imaging according to some embodiments of the present application;

[0028] Figure 7 is a schematic diagram of an exemplary MRI pulse sequence for implementing multi-tasking techniques;

[0029] Figure 8 is a schematic diagram of an exemplary MRI pulse sequence for implementing SMS multi-tasking techniques according to some embodiments of the present application;

[0030] Figure 9 is a schematic diagram of another exemplary MRI pulse sequence for implementing SMS multi-tasking techniques according to some embodiments of the present application; and

[0031] Figure 10A flowchart of an exemplary process for generating one or more target images of a target slice position according to some embodiments of the present application. Detailed implementation manners

[0032] To more clearly illustrate the technical solutions of the embodiments of the present application, the accompanying drawings required for the description of the embodiments will be briefly introduced below. However, those skilled in the art should understand that the present application can be implemented without these details. In other cases, well-known methods, processes, systems, components, and / or circuits have been described at a higher level to avoid unnecessarily obscuring aspects of the present application. For those of ordinary skill in the art, it is obvious that various changes can be made to the disclosed embodiments, and the general principles defined in the present application can be applied to other embodiments and application scenarios without departing from the principles and scope of the present application. Therefore, the present application is not limited to the disclosed embodiments, but conforms to the broadest scope consistent with the scope of the patent application.

[0033] The terms used in the present application are for the purpose of describing specific example embodiments only and are not restrictive. As used in the present application, the singular forms "a", "an", and "the" may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that, as used in the specification of the present application, the terms "including" and "comprising" only indicate the presence of the described features, integers, steps, operations, components, and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, components, parts, and / or their combinations.

[0034] It should be understood that the terms "system", "engine", "unit", "module", and / or "block" used herein are a way to distinguish different components, elements, parts, portions, or fittings at different levels in ascending order. However, these terms can be replaced by other expressions if the same purpose can be achieved.

[0035] Generally, the terms "module", "unit", or "block" used herein refer to logic embodied in hardware or firmware, or a collection of software instructions. The modules, units, or blocks described herein can be implemented as software and / or hardware and can be stored in any type of non-transitory computer-readable medium or another storage device. In some embodiments, the software modules / units / blocks can be compiled and linked to an executable program. It should be understood that the software modules can call from other modules / units / blocks or from themselves, and / or can be called in response to detected events or interrupts. Configured in a computing device (e.g., as Figure 3Software modules / units / blocks executed on the processor 310 shown can be provided on a computer-readable medium (e.g., optical disc, digital video disc, flash drive, magnetic disk, or any other tangible medium), or downloaded in digital form (initially stored in a compressed or installable format and requiring installation, decompression, or decryption before execution). The software code can be stored partially or entirely in the storage device of the computing device performing the operations and applied in the operation of the computing device. The software instructions can be embedded in firmware, such as EPROM. It should also be understood that hardware modules / units / blocks can include connected logic components, such as gates and flip-flops, and / or can include programmable units, such as programmable gate arrays or processors. The modules / units / blocks or computing device functions described herein can be implemented as software modules / units / blocks, but can be represented by hardware or firmware. Generally, the modules / units / blocks described herein refer to logical modules / units / blocks, which can be combined with other modules / units / blocks or divided into sub-modules / sub-units / sub-blocks, although they are physically organized or storage devices. This description can apply to a system, an engine, or a part thereof.

[0036] It can be understood that, unless the context clearly indicates otherwise, when a unit, engine, module, or block is referred to as being "on," "connected to," or "coupled to" another unit, engine, module, or block, it can be directly on, connected to, or coupled to or communicate with the other unit, engine, module, or block, or there may be intermediate units, engines, modules, or blocks. In this application, the term "and / or" can include any one or more of the related listed items or a combination thereof. The term "image" in this application is used to collectively refer to image data (e.g., scanned data, projection data) and / or various forms of images, including two-dimensional (2D) images, three-dimensional (3D) images, four-dimensional (4D) images, etc. The terms "pixel" and "voxel" in this application can be used interchangeably to refer to the elements of an image.

[0037] It should be understood that although terms such as "first," "second," "third," 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, without departing from the scope of the exemplary embodiments of this application, a first element can be referred to as a second element, and similarly, a second element can be referred to as a first element.

[0038] In view of the following description of the accompanying drawings, these and other features, characteristics of the present application, the functions and operating methods of related structural elements, as well as the combination of components and manufacturing economy, may become more apparent. These accompanying drawings all form part of the specification of the present application. However, it should be understood that the accompanying drawings are only for the purpose of illustration and description, and are not intended to limit the scope of the present application. It should be understood that the accompanying drawings are not drawn to scale.

[0039] The present application provides systems and methods for non-invasive biomedical imaging for purposes such as disease diagnosis or research. Although the systems and methods shown in the present application are mainly for SMS multi-task imaging using an MRI system. It should be understood that this is only for illustrative purposes. The systems and methods in the present application can be applied to any other imaging system. In some embodiments, the imaging system may include a single-modal imaging system and / or a multi-modal imaging system. The single-modal imaging system may include, for example, an MRI system. The multi-modal imaging system may include, for example, an X-ray imaging magnetic resonance imaging (X-ray-MRI) system, a single photon emission computed tomography magnetic resonance imaging (SPECT-MRI) system, a digital subtraction angiography magnetic resonance imaging (DSA-MRI) system, a computed tomography magnetic resonance imaging (MRI-CT) system, a positron emission tomography magnetic resonance imaging (PET-MRI) system, etc.

[0040] One aspect of the present application relates to systems and methods for MRI (magnetic resonance imaging), and more particularly, to systems and methods for SMS multi-task imaging that combines SMS technology and multi-task technology. SMS technology typically utilizes multi-band excitation pulses to simultaneously excite at least two slice positions of an object, which can accelerate the scanning process. Conventionally, additional reference scans may be required to obtain reference data for each slice position for slice separation. For example, a reference slice image of the slice position can be reconstructed based on the reference scan, and the coil sensitivity maps of different receivers / coils can be determined. Based on the coil sensitivity maps, the slice images of each slice position can be separated from the aliased image obtained from the SMS system. However, the additional reference scans may result in additional scan time, compromising the advantages of SMS technology.

[0041] Multitask technology can utilize a single MRI scan to acquire MRI data related to multiple time dimensions, that is, to achieve multitasking. Multitask technology can be used to conceptualize motion, relaxation, and other dynamics as different time dimensions and resolve multiple time dimensions. By capturing, rather than avoiding, motion, relaxation, and other dynamics, multitask technology can effectively perform quantitative measurements on an object without using electrocardiogram (ECG) triggering, breath-holding, etc. For example, multitask technology can enable non-ECG and free-breathing T1 mapping, non-ECG and free-breathing T2 mapping, and non-ECG and time-resolved T1 mapping for myocardial perfusion and dynamic contrast-enhanced imaging. In other words, multitask technology can provide a more effective, reliable, and comfortable imaging method for solving long-standing problems in MRI.

[0042] However, traditional multitasking techniques need to separately acquire MRI data at different slice positions and can only use part of the MRI data for image reconstruction, with limited imaging efficiency. For example, multitask technology is commonly used in cardiac scans for 2D T1 cine imaging, where MRI data for each single-layer position of the object's heart needs to be separately acquired. The MRI data at a single slice position can include at least two auxiliary signals, and the at least two auxiliary signals can be processed to resolve cardiac motion and respiratory motion. The cardiac scan time is long and the imaging efficiency is low. In typical short-axis cardiac imaging, due to the obvious contraction and relaxation in the middle and bottom of the heart, the auxiliary signals at the slice positions in the middle or bottom of the heart can provide relatively accurate motion information. However, since the contraction and relaxation at the slice positions near the apex of the heart are not obvious, the accuracy of the auxiliary signals at these slice positions is limited, and it is difficult to resolve the cardiac motion at these slice positions based on these auxiliary signals.

[0043] To combine the advantages of multitask technology and SMS technology and solve the problems of these two technologies, the present application provides a system and method for SMS multitask imaging. Specifically, the system and method can acquire at least two auxiliary signals and at least two imaging signals, and the at least two auxiliary signals and the at least two imaging signals can be collected by simultaneously applying an MRI pulse sequence to at least two slice positions of an object (e.g., a patient). During the application of the MRI pulse sequence, phase modulation can be applied to at least one of the at least two slice positions such that the at least two slice positions have different phases during the readout of at least one imaging signal. For each of at least one target slice position among the at least two slice positions, the system and method can generate at least one target image of the target slice position based on the at least two auxiliary signals and the at least two imaging signals.

[0044] Compared with traditional multi-tasking techniques, the SMS multi-tasking imaging technique of the present application simultaneously images at least two slice positions, thus having a higher scanning efficiency (e.g., reduced scanning time). In addition, the SMS multi-tasking imaging technique allows for the acquisition of auxiliary signals at at least two slice positions instead of a single slice position, which avoids the problem of limited accuracy of the auxiliary signal at the apical slice position and improves the data quality and the dynamic tracking effect based thereon. Compared with traditional SMS techniques, the SMS multi-tasking imaging technique disclosed herein applies phase modulation for slice separation to the slice positions, whereby it is not necessary to perform an additional scan for generating a reference slice image and errors that may occur during the additional scan are avoided.

[0045] Figure 1 is a schematic diagram of an exemplary MRI system 100 shown in some embodiments of the present application. As Figure 1 shown, the MRI system 100 may include an MRI scanner 110, a processing device 120, a storage device 130, one or more terminals 140, and a network 150. In some embodiments, the MRI scanner 110, the processing device 120, the storage device 130, and / or the terminal 140 may be interconnected and / or communicate with each other via a wireless connection, a wired connection, or a combination thereof. The connections between the components in the MRI system 100 may be variable. For example, the MRI scanner 110 may be connected to the processing device 120 via the network 150. As another example, the MRI scanner 110 may be directly connected to the processing device 120.

[0046] The MRI scanner 110 may be configured to scan an object (or a part of the object) to acquire image data, such as echo signals (or MRI signals) associated with the object. For example, the MRI scanner 110 may detect at least two echo signals by applying an MRI pulse sequence to the object. In some embodiments, as described in connection with Figure 2 the MRI scanner 110 may include, for example, a main magnet, gradient coils (or also referred to as spatial encoding coils), radio frequency (RF) coils, etc. In some embodiments, depending on the type of the main magnet, the MRI scanner 110 may be classified into a permanent magnet MRI scanner, a superconducting electromagnet MRI scanner, a resistive electromagnet MRI scanner, etc. In some embodiments, depending on the strength of the magnetic field, the MRI scanner 110 may be classified into a high-field MRI scanner, a mid-field MRI scanner, and a low-field MRI scanner, etc.

[0047] The object scanned by the MRI scanner 110 can be biological or non - biological. For example, the object can include a patient, an artificial object, etc. As another example, the object can include a specific part, organ, tissue, and / or body part of a patient. By way of example only, the object can include the head, brain, neck, body, shoulder, arm, chest, heart, stomach, blood vessels, soft tissue, knee, foot, etc., or a combination thereof.

[0048] For illustrative purposes, a coordinate system 160 including an X - axis, a Y - axis, and a Z - axis is provided in Figure 1 . Figure 1 The X - axis and the Z - axis shown can be horizontal, and the Y - axis can be vertical. As shown, the positive X - direction along the X - axis can be the direction from the right side to the left side of the MRI scanner 110 when viewed from the front of the MRI scanner 110; along Figure 1 the positive Y - direction along the Y - axis shown can be from the lower part to the upper part of the MRI scanner 110; Figure 1 the positive Z - direction along the Z - axis shown can be the direction in which the object moves out of the scan channel (or aperture) of the MRI scanner 110.

[0049] In some embodiments, the MRI scanner 110 can be guided to select an anatomical slice of the object in the slice - selection direction and scan the anatomical slice to obtain at least two echo signals from the slice. During the scan, spatial encoding within the slice can be achieved by spatial - encoding coils (e.g., X - coils and Y - coils) along the phase - encoding direction and the frequency - encoding direction. The echo signals can be sampled, and the corresponding sampled data can be stored in a k - space matrix for image reconstruction. For illustrative purposes, the slice - selection direction herein can correspond to the Z - direction defined by the coordinate system 160 and the Kz - direction in k - space; the phase - encoding direction can correspond to the Y - direction defined by the coordinate system 160 and the Ky - direction in k - space; the frequency - encoding direction can correspond to the X - direction defined by the coordinate system 160 and the Kx - direction in k - space. It should be noted that the slice - selection direction, the phase - encoding direction, and the frequency - encoding direction can be modified according to actual needs, and such modification may not exceed the scope of this application. More descriptions of the MRI scanner 110 can be found elsewhere in this application. For example, see Figure 2 and its description.

[0050] The processing device 120 may process data and / or information obtained from the MRI scanner 110, the storage device 130, and / or the terminal 140. For example, the processing device 120 may acquire at least two auxiliary signals and at least two imaging signals by simultaneously applying an MRI pulse sequence to at least two slice positions of an object. As another example, for each of at least one target slice position among the at least two slice positions, the processing device 120 may generate at least one target image of the target slice position based on the at least two auxiliary signals and the at least two imaging signals.

[0051] In some embodiments, the processing device 120 may be a single server or a server group. The server group may be centralized or distributed. In some embodiments, the processing device 120 may be local or remote. For example, the processing device 120 may access information and / or data from the MRI scanner 110, the storage device 130, and / or the terminal 140 via the network 150. As another example, the processing device 120 may be directly connected to the MRI scanner 110, the terminal 140, and / or the storage device 130 to access information and / or data. In some embodiments, the processing device 120 may be implemented on a cloud platform. For example, the cloud platform may include a private cloud, a public cloud, a hybrid cloud, a community cloud, a distributed cloud, an inter-cloud, a multi-cloud, etc., or a combination thereof. In some embodiments, the processing device 120 may be implemented by the computing device 300 having one or more components as Figure 3 described.

[0052] The storage device 130 may store data, instructions, and / or any other information. In some embodiments, the storage device 130 may store data obtained from the MRI scanner 110, the processing device 120, and / or the terminal 140. In some embodiments, the storage device 130 may store data and / or instructions that the processing device 120 may execute or use to perform the exemplary methods described in this application. In some embodiments, the storage device 130 may include a mass storage device, a removable storage device, a volatile read-write memory, a read-only memory (ROM), etc., or a combination thereof. Exemplary mass storage devices may include magnetic disks, optical disks, solid state drives, etc. Exemplary removable storage devices may include flash drives, floppy disks, optical disks, memory cards, compact disks, magnetic tapes, etc. Exemplary volatile read-write memories may include random access memory (RAM). Exemplary RAM may include dynamic RAM (DRAM), double data rate synchronous dynamic RAM (DDR-SDRAM), static RAM (SRAM), thyristor RAM (T-RAM), zero capacitor RAM (Z-RAM), etc. Exemplary ROM may include mask ROM (MROM), programmable ROM (PROM), erasable programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), compact disk ROM (CD-ROM), digital versatile disk ROM, etc. In some embodiments, as described elsewhere in this application, the storage device 130 may be implemented on a cloud platform.

[0053] In some embodiments, the storage device 130 may be connected to the network 150 to communicate with one or more other components in the MRI system 100 (e.g., the MRI scanner 110, the processing device 120, and / or the terminal 140). One or more components of the MRI system 100 may access the data or instructions stored in the storage device 130 through the network 150. In some embodiments, the storage device 130 may be part of the processing device 120 or the terminal 140.

[0054] The terminal 140 can implement the interaction between the user and the MRI system 100. For example, the terminal 140 can receive an instruction from the user to scan an object by the MRI scanner 110. As another example, the terminal 140 can receive a processing result (e.g., a target image of the target slice position of the object) from the processing device 120 and display the processing result to the user. In some embodiments, the terminal 140 can be connected and / or communicate with the MRI scanner 110, the processing device 120, and / or the storage device 130. In some embodiments, the terminal 140 can include a mobile device 140-1, a tablet computer 140-2, a laptop computer 140-3, etc., or a combination thereof. For example, the mobile device 140-1 can include a mobile phone, a personal digital assistant (PDA), a gaming device, a navigation device, a point of sale (POS) device, a laptop computer, a tablet computer, a desktop computer, etc., or a combination thereof. In some embodiments, the terminal 140 can include an input device, an output device, etc. The input device can include alphanumeric keys or other keys, and the alphanumeric keys or other keys can be input via a keyboard, a touch screen (e.g., having tactile or haptic feedback), voice input, eye tracking input, a brain monitoring system, or any other similar input mechanism. The input information received by the input device can be sent to the processing device 120 via, for example, a bus for further processing. Other types of input devices can include cursor control devices, such as a mouse, a trackball, or cursor direction keys, etc. The output device can include a display, a speaker, a printer, etc., or a combination thereof. In some embodiments, the terminal 140 can be a part of the processing device 120 or the MRI scanner 110.

[0055] Network 150 may include any suitable network that can facilitate the exchange of information and / or data of MRI system 100. In some embodiments, one or more components of MRI system 100 (e.g., MRI scanner 110, processing device 120, storage device 130, terminal 140, etc.) may transmit information and / or data with one or more other components of MRI system 100 via network 150. For example, processing device 120 may obtain image data (e.g., echo signals) from MRI scanner 110 via network 150. As another example, processing device 120 may obtain user instructions from terminal 140 via network 150. Network 150 may include a public network (e.g., the Internet), a private network (e.g., local area network (LAN), wide area network (WAN), etc.), a wired network (e.g., Ethernet), a wireless network (e.g., 802.11 network, Wi-Fi network, etc.), a cellular network (e.g., long term evolution (LTE) network), a frame relay network, a virtual private network (“VPN”), a satellite network, a telephone network, routers, hubs, switches, server computers, etc., or a combination thereof. For example, network 150 may include a cable network, a wired network, an optical fiber network, a telecommunication network, an intranet, a wireless local area network (WLAN), a metropolitan area network (MAN), a public switched telephone network (PSTN), a BluetoothTM network, a ZigBeeTM network, a near field communication (NFC) network, etc., or a combination thereof. In some embodiments, network 150 may include one or more network access points. For example, network 150 may include wired and / or wireless network access points, such as base stations and / or Internet exchange points, through which one or more components of MRI system 100 may be connected to network 150 to exchange data and / or information.

[0056] This description is intended to be illustrative, not limiting, of the scope of the application. Many alternatives, modifications, and variations will be apparent to those skilled in the art. The features, structures, methods, and characteristics of the exemplary embodiments described herein may be combined in various ways to obtain additional and / or alternative exemplary embodiments. In some embodiments, MRI system 100 may include one or more additional components, and / or one or more of the components described above may be omitted. Additionally or alternatively or alternatively, two or more components of MRI system 100 may be integrated into a single component. For example, processing device 120 may be integrated into MRI scanner 110. As another example, a component of MRI system 100 may be replaced by another component that can implement the functions of the component. In some embodiments, storage device 130 may be a data memory including a cloud computing platform, such as a public cloud, a private cloud, a community cloud, and a hybrid cloud, etc. However, these changes and modifications do not depart from the scope of the application.

[0057] Figure 2Schematic diagram of an exemplary MRI scanner 110 as shown in some embodiments of the present application. Figure 2 One or more components of the MRI scanner 110 are shown. As shown, the main magnet 201 can generate a first magnetic field (or referred to as the main magnetic field), and the first magnetic field can be applied to an object (also referred to as the target) exposed within the magnetic field. The main magnet 201 can include a resistive magnet or a superconducting magnet, both of which require a power source (not shown) for operation. Alternatively, the main magnet 201 can include a permanent magnet. The main magnet 201 can include an aperture in which the object is placed. The main magnet 201 can also control the uniformity of the generated main magnetic field. Some shim coils may be located in the main magnet 201. The shim coils placed in the gap of the main magnet 201 can compensate for the non-uniformity of the magnetic field of the main magnet 201. The shim coils can be energized by a shim power supply.

[0058] The gradient coils 202 can be located within the main magnet 201. The gradient coils 202 can generate a second magnetic field (or referred to as the gradient field, including gradient fields Gx, Gy, and Gz). The second magnetic field can be superimposed on the main magnetic field generated by the main magnet 201 and distort the main magnetic field such that the magnetic orientation of the protons of the object can vary with their position within the gradient field, thereby encoding spatial information into the echo signals generated in the imaging region. The gradient coils 202 can include an X coil (e.g., configured to generate a gradient field Gx corresponding to the X direction), a Y coil (e.g., configured to generate a gradient field Gy corresponding to the Y direction), and / or a Z coil (e.g., configured to generate a gradient field Gz corresponding to the Z direction) ( Figure 2 not shown in the figure). In some embodiments, the Z coil can be designed based on a circular (Maxwell) coil design, while the X coil and Y coil can be designed based on a saddle-shaped (Golay) coil configuration. The three sets of coils can generate three different magnetic fields for position encoding. The gradient coils 202 can allow spatial encoding of the echo signals for image construction. The gradient coils 202 can be connected to one or more of an X gradient amplifier 204, a Y gradient amplifier 205, or a Z gradient amplifier 206. One or more of the three amplifiers can be connected to a waveform generator 216. The waveform generator 216 can generate gradient waveforms applied to the X gradient amplifier 204, the Y gradient amplifier 205, and / or the Z gradient amplifier 206. The amplifiers can amplify the waveforms. The amplified waveforms can be applied to one of the coils in the gradient coils 202 to generate a magnetic field along the X-axis, Y-axis, or Z-axis, respectively. The gradient coils 202 can be designed for a closed-bore MRI scanner or an open-bore MRI scanner. In some cases, all three sets of coils of the gradient coils 202 can be energized and thereby generate three gradient fields. In some embodiments of the present application, the X coil and Y coil can be energized to generate gradient fields in the X direction and Y direction. As used herein, Figure 2The X-axis, Y-axis, Z-axis, X-direction, Y-direction, and Z-direction in the description of Figure 1 are the same as or similar to those described in

[0059] In some embodiments, a radio frequency (RF) coil 203 may be located within the main magnet 201 and serve as a transmitter, a receiver, or both a transmitter and a receiver. The RF coil 203 may be connected to RF electronics 209, which may be configured as or serve as one or more integrated circuits (ICs) that function as a waveform transmitter and / or a waveform receiver. The RF electronics 209 may be connected to a radio frequency power amplifier (RFPA) 207 and an analog-to-digital converter (ADC) 208.

[0060] When serving as a transmitter, the RF coil 203 may generate an RF signal that provides a third magnetic field for generating an echo signal related to a region of an object to be imaged. The third magnetic field may be perpendicular to the main magnetic field. A waveform generator 216 may generate RF pulses. The RF pulses may be amplified by the RF power amplifier 207, processed by the RF electronics 209, and applied to the RF coil 203 to generate an RF signal in response to a strong current generated by the RF electronics 209 based on the amplified RF pulses.

[0061] When serving as a receiver, the RF coil may be responsible for detecting the echo signal. After excitation, the echo signal generated by the object may be sensed by the RF coil 203. Then, a receiving amplifier may receive the sensed echo signal from the RF coil 203, amplify the sensed echo signal, and provide the amplified echo signal to the ADC 208. The ADC 208 may convert the echo signal from an analog signal to a digital signal. The digital echo signal may then be sent to a processing device 120 for sampling.

[0062] In some embodiments, the gradient coil 202 and the RF coil 203 may be circumferentially positioned relative to the object. Those skilled in the art will appreciate that the main magnet 201, the gradient coil 202, and the RF coil 203 may be located in various configurations around the object.

[0063] In some embodiments, the radio frequency power amplifier 207 may amplify radio frequency pulses (e.g., the power of the radio frequency pulse, the voltage of the radio frequency pulse), and the generated amplified radio frequency pulses are used to drive the radio frequency coil 203. The radio frequency power amplifier 207 may include a transistor-based radio frequency power amplifier, a vacuum tube-based radio frequency power amplifier, etc., or any combination thereof. The transistor-based radio frequency power amplifier may include one or more transistors. The vacuum tube-based radio frequency power amplifier may include a triode, a tetrode, a klystron, etc., or any combination thereof. In some embodiments, the radio frequency power amplifier 207 may include a linear radio frequency power amplifier or a non-linear radio frequency power amplifier. In some embodiments, the radio frequency power amplifier 207 may include one or more radio frequency power amplifiers.

[0064] In some embodiments, the MRI scanner 110 may further include an object positioning system (not shown). The object positioning system may include an object support and a transfer device. The object may be placed on the object support and positioned within the aperture of the main magnet 201 by the transfer device.

[0065] An MRI system (e.g., the MRI system 100 disclosed in the present application) can generally be used to obtain internal images of a specific region of interest (ROI) from a patient, and the region of interest can be used for purposes such as diagnosis, treatment, etc., or a combination thereof. The MRI system includes a main magnet (e.g., the main magnet 201) assembly for providing a strong and uniform main magnetic field to align the individual magnetic moments of hydrogen atoms in the patient's body. In this process, the hydrogen atoms oscillate around their magnetic poles at their characteristic Larmor frequency. If the tissue is subjected to an additional magnetic field that is tuned to the Larmor frequency, the hydrogen atoms absorb additional energy, thereby rotating the net alignment torque of the hydrogen atoms. The additional magnetic field can be provided by a radio frequency excitation signal (e.g., the radio frequency signal generated by the radio frequency coil 203). When the additional magnetic field is removed, the magnetic moments of the hydrogen atoms rotate back to align with the main magnetic field, thereby emitting an echo signal. The echo signal is received and processed to form an MRI image. T1 relaxation can be the process by which the net magnetization grows / returns to its initial maximum value parallel to the main magnetic field. T1 can be the time constant for the regeneration of longitudinal (e.g., along the main magnetic field) magnetization. T2 relaxation can be the process of decay or dephasing of the transverse component of magnetization. T2 can be the time constant for the decay / dephasing of transverse magnetization.

[0066] If the main magnetic field is uniformly distributed throughout the patient's body, the radiofrequency excitation signal may non-selectively excite all hydrogen atoms in the object. Therefore, in order to image a specific body part of the patient, magnetic field gradients Gx, Gy, and Gz in the x, y, and z directions (e.g., generated by gradient coil 202) can be superimposed on the uniform magnetic field. These magnetic field gradients have specific times, frequencies, and phases such that the radiofrequency excitation signal excites the hydrogen atoms in the desired slice of the patient's body, and unique phase and frequency information is encoded in the echo signal based on the position of the hydrogen atoms in the "image slice".

[0067] Typically, the portion of the patient's body to be imaged is scanned through a series of measurement cycles, where the radiofrequency excitation signal and the magnetic field gradients Gx, Gy, and Gz vary according to the MRI imaging protocol being used. The protocol can be designed for one or more tissues, diseases, and / or clinical scenarios to be imaged. The protocol can include a number of pulse sequences for different planes and / or with different parameters. The pulse sequences can include spin echo sequences, gradient echo sequences, diffusion sequences, inversion recovery sequences, etc., or any combination thereof. For example, spin echo sequences can include fast spin echo (FSE) pulse sequences, turbo spin echo (TSE) pulse sequences, rapid acquisition with relaxation enhancement (RARE) pulse sequences, half Fourier acquisition single shot turbo spin echo (HASTE) pulse sequences, turbo gradient spin echo (TGSE) pulse sequences, etc., or any combination thereof. As another example, gradient echo sequences can include balanced steady state free precession (bSSFP) pulse sequences, spoiled gradient echo (GRE) pulse sequences, echo planar imaging (EPI) pulse sequences, steady state free precession (SSFP), etc., or any combination thereof. The protocol can also include information about image contrast and / or ratio, ROI, slice thickness, imaging type (e.g., T1-weighted imaging, T2-weighted imaging, proton density weighted imaging, etc.), T1, T2, echo type (spin echo, fast spin echo (FSE), fast recovery FSE, single shot FSE, gradient echo, fast imaging with steady state processing, etc.), flip angle value, acquisition time (TA), echo time (TE), repetition time (TR), echo train length (ETL), number of phases, number of excitations (NEX), inversion time, bandwidth (e.g., radiofrequency receiver bandwidth, radiofrequency transmitter bandwidth, etc.), etc., or any combination thereof. For each MRI scan, the generated echo signal can be digitized and processed to reconstruct an image according to the MRI imaging protocol used.

[0068] Figure 3FIG. 0 is a schematic diagram of exemplary hardware and / or software components of a computing device 300 as shown in some embodiments of the present application. The computing device 300 can be used to implement any component of the MRI system 100 as described herein. For example, the processing device 120 and / or the terminal 140 can be implemented on the computing device 300 through its hardware, software program, firmware, or a combination thereof, respectively. Although only one such computing device is shown for convenience, the computer functions related to the MRI system 100 described herein can be implemented in a distributed manner on at least two similar platforms to distribute the processing load. As Figure 3 shown, the computing device 300 may include a processor 310, a storage device 320, an input device / output device (I / O) 330, and a communication port 340.

[0069] The processor 310 can execute computer instructions (e.g., program code) according to the techniques described herein and perform the functions of the processing device 120. The computer instructions can include, for example, routines, programs, objects, components, data structures, processes, modules, and functions that perform the specific functions described herein. For example, the processor 310 can process image data obtained from the MRI scanner 110, the terminal 140, the storage device 130, and / or any other component of the MRI system 100. In some embodiments, the processor 310 can include one or more hardware processors, such as a microcontroller, a microprocessor, a reduced instruction set computer (RISC), an application specific integrated circuit (ASICs), an application specific instruction set processor (ASIP), a central processing unit (CPU), a graphics processing unit (GPU), a physics processing unit (PPU), a microcontroller unit, a digital signal processor (DSP), a field programmable gate array (FPGA), an advanced RISC machine (ARM), a programmable logic device (PLD), any circuit or processor capable of performing one or more functions, etc., or any combination thereof.

[0070] For illustration purposes only, only one processor is described in the computing device 300. However, it should be noted that the computing device 300 in the present application may also include at least two processors. Therefore, the operations and / or method operations performed by one processor as described in the present application can also be performed jointly or separately by at least two processors. For example, if in the present application, the processor of the computing device 300 performs operation A and operation B simultaneously, it should be understood that operation A and operation B can also be performed jointly or separately by two or more different processors in the computing device 300 (e.g., the first processor performs operation A, the second processor performs operation B, or the first and second processors jointly perform operation A and B).

[0071] The storage device 320 may store data / information obtained from the MRI scanner 110, the terminal 140, the storage device 130, and / or any other component of the MRI system 100. In some embodiments, the storage device 320 may include a mass storage device, a removable storage device, a volatile read-write memory, a read-only memory (ROM), etc., or any combination thereof. In some embodiments, the storage device 320 may store one or more programs and / or instructions to execute the exemplary methods described in the present application. For example, the storage device 320 may store a program for the processing device 120 to execute SMS multi-task imaging.

[0072] The input device / output device 330 may input and / or output signals, data, information, etc. In some embodiments, the input device / output device 330 may enable a user to interact with the processing device 120. In some embodiments, the input device / output device 330 may include an input device and an output device. The input device may include alphanumeric keys or other keys, which may be input via a keyboard, a touch screen (e.g., having tactile or haptic feedback), voice input, eye tracking input, a brain monitoring system, or any other similar input mechanism. The input information received by the input device may be sent to another component (e.g., the processing device 120) via, for example, a bus for further processing. Other types of input devices may include cursor control devices, such as a mouse, a trackball, or cursor direction keys, etc. The output device may include a display (e.g., a liquid crystal display (LCD), a light-emitting diode (LED)-based display, a flat panel display, a curved screen, a television device, a cathode ray tube (CRT), a touch screen), a speaker, a printer, etc., or a combination thereof.

[0073] The communication port 340 may be connected to a network (e.g., the network 150) to facilitate data communication. The communication port 340 may establish a connection between the processing device 120 and the MRI scanner 110, the terminal 140, and / or the storage device 130. The connection may be a wired connection, a wireless connection, any other communication connection capable of data transmission and / or reception, and / or any combination of these connections. The wired connection may include, for example, a cable, an optical fiber cable, a telephone line, etc., or any combination thereof. The wireless connection may include, for example, a BluetoothTM connection, a Wi-FiTM connection, a WiMaxTM connection, a WLAN connection, a ZigBeeTM connection, a mobile network connection (e.g., 3G, 4G, 5G), etc., or a combination thereof. In some embodiments, the communication port 340 may be / including a standardized communication port, such as RS232, RS485, etc. In some embodiments, the communication port 340 may be a specially designed communication port. For example, the communication port 340 may be designed according to the Digital Imaging and Communications in Medicine (DICOM) protocol.

[0074] Figure 4 It is a schematic diagram of exemplary hardware and / or software components of the mobile device 400 shown in some embodiments of the present application. In some embodiments, one or more components of the MRI system 100 (e.g., the terminal 140 and / or the processing device 120) can be implemented on the mobile device 400.

[0075] As Figure 4 shown, the mobile device 400 can include a communication platform 410, a display 420, a graphics processing unit (GPU) 430, a central processing unit (CPU) 440, an input device / output device 450, a memory 460, and a storage 490. In some embodiments, any other suitable components, including but not limited to a system bus or a controller (not shown), can also be included in the mobile device 400. In some embodiments, a mobile operating system 470 (e.g., iOS™, Android™, Windows Phone™) and one or more applications 480 can be loaded from the storage 490 into the memory 460 for execution by the CPU 440. The application 480 can include a browser or any other suitable mobile application for receiving and presenting information related to the MRI system 100. The interaction between the user and the information stream can be realized via the input device / output device 450 and provided to the processing device 120 and / or other components of the MRI system 100 via the network 150.

[0076] To implement the various modules, units, and their functions described in the present application, a computer hardware platform can be used as the hardware platform for one or more components described herein. A computer with user interface elements can be used to implement a personal computer (PC) or any other type of workstation or terminal device. If the computer is appropriately programmed, the computer can also be used as a server.

[0077] Figure 5 It is a block diagram of an exemplary processing device 120 shown in some embodiments of the present application. As Figure 5 shown, the processing device 120 can include an acquisition module 501 and a generation module 502.

[0078] The acquisition module 501 can be configured to acquire at least two auxiliary signals (multiple auxiliary signals) and at least two imaging signals (multiple imaging signals), where the at least two auxiliary signals and the at least two imaging signals are acquired by simultaneously applying an MRI pulse sequence to at least two slice positions of an object. The auxiliary signals can include high temporal resolution data related to at least one temporal variation dimension of the object (or imaging slice position) for implementing multitasking techniques. The imaging signals can include high spatial resolution image data related to at least one spatial variation dimension of the object (or imaging slice position). In some embodiments, the MRI pulse sequence can be specifically designed to implement SMS techniques and multitasking techniques. More descriptions regarding the acquisition of auxiliary signals and imaging signals can be found elsewhere in this application. See, for example, 601 and its related descriptions.

[0079] For each of one or more target slice positions of the slice positions, the generation module 502 can be configured to generate one or more target images of the target slice position based on the auxiliary signals and the imaging signals. The target slice positions can include all or a part of the slice positions. The target images of the target slice positions can include static images and / or dynamic images of the target slice positions. In some embodiments, for each of one or more target slice positions, the generation module 502 can determine one or more temporal basis functions related to the temporal variation dimension of the target slice position and generate one or more spatial basis functions related to the spatial variation dimension of the target slice position based on the temporal basis functions and the imaging signals. The generation module 502 can further generate one or more target images of the target slice position based on the one or more temporal basis functions and the one or more spatial basis functions. More descriptions regarding the generation of one or more target images can be found elsewhere in this application. See, for example, 602 and its related descriptions.

[0080] It should be noted that the above description is provided for illustrative purposes only and is not intended to limit the scope of this application. For those of ordinary skill in the art, various changes and modifications can be made according to the description of this application. However, these changes and modifications do not depart from the scope of this application. For example, the processing device 120 can include one or more additional modules, such as a storage module (not shown) for storing data. As another example, one or more modules of the above-mentioned processing device 120 can be omitted. Additionally or alternatively or instead, the modules of the processing device 120 can be divided into two or more units. For example, the generation module 502 can be divided into a temporal basis function determination unit, a spatial basis function determination unit, and a target image generation unit.

[0081] Figure 6FIG. 0 is a flow chart of an exemplary process for SMS multi - task imaging according to some embodiments of the present application. In some embodiments, process 600 may be executed by MRI system 100. For example, process 600 may be implemented as a set of instructions (e.g., an application program) stored in a storage device (e.g., storage device 130, storage device 320, and / or storage device 490). In some embodiments, processing device 120 (e.g., processor 310 of computing device 300, CPU 440 of mobile device 400, and / or Figure 5 one or more modules as shown) may execute the set of instructions and may be correspondingly instructed to execute process 600.

[0082] In 601, processing device 120 (e.g., acquisition module 501) may acquire at least two auxiliary signals (multiple auxiliary signals) and at least two imaging signals (multiple imaging signals), where the at least two auxiliary signals (multiple auxiliary signals) and at least two imaging signals (multiple imaging signals) are acquired by simultaneously applying an MRI pulse sequence to at least two slice positions (multiple slice positions) of an object.

[0083] As used herein, the object may be biological or non - biological, e.g., a patient or a particular part, organ, tissue, and / or body part of a patient. By way of example only, the object may include a head, brain, neck, body, shoulder, arm, chest, heart, stomach, blood vessels, soft tissue, knee, foot, etc., or a combination thereof. In some embodiments, the object may include at least a part of the heart. A slice position of the object refers to a transverse plane of the object (e.g., a plane parallel to the X - Y plane defined by the Figure 1 coordinate system 160 as shown). The number of imaging slice positions may be any positive number greater than 1, e.g., 2, 3, 4, 5, etc. The imaging slice positions may be located at any position of the object. For example, the object may include a patient's heart, and the slice positions may include multiple slice positions located at the apex, middle, and bottom of the heart.

[0084] In some embodiments, processing device 120 may acquire the auxiliary signals and imaging signals from an MRI scanner. The MRI scanner may include one or more Figure 1 and Figure 2Components similar to the described MRI scanner 110. For example, the processing device 120 can instruct the MRI scanner to perform an MRI scan on an object. During the MRI scan, the MRI scanner can simultaneously apply an MRI pulse sequence to a slice position of the object and collect MRI signals from the object, including auxiliary signals and imaging signals. The collected auxiliary signals and imaging signals can be sent from the MRI scanner to the processing device 120 for further analysis. Alternatively, the collected auxiliary signals and imaging signals can be first collected by the MRI scanner and stored in a storage device (e.g., storage device 130, storage device 320, and / or storage device 490). The processing device 120 can obtain the auxiliary signals and imaging signals from the storage device. In some embodiments, during the MRI scan (i.e., during the application of the MRI pulse sequence), the object can be in a free-breathing state.

[0085] The auxiliary signals can include high temporal resolution data related to at least one temporal variation dimension of the object (or the imaging slice position), and the high temporal resolution data can be used to implement multitasking techniques. Exemplary temporal variation dimensions can be related to cardiac motion, respiratory motion, T1 relaxation, T2 relaxation, chemical exchange saturation transfer (CEST), contrast agent dynamics, T1ρ contrast, molecular diffusion, elapsed time, etc., or any combination thereof. It should be noted that the exemplary temporal variation dimensions are provided for illustrative purposes only and are not restrictive. The at least one temporal variation dimension can include any dimension that reflects the temporal variation characteristics or dynamic information of the object. In some embodiments, the auxiliary signals can be used to estimate at least one temporal basis function related to the at least one temporal variation dimension, which will be described in detail in Figure 10 which will be described in detail below.

[0086] In some embodiments, the auxiliary signal may correspond to the same subset of the k-space (e.g., the k-space includes one or more k-space lines), and is collected by repeatedly sampling the subset of the k-space at a high sampling frequency. For example, the auxiliary signal may correspond to the same k-space line in the k-space, and can be obtained by repeatedly sampling the k-space line using a high sampling frequency. As used herein, the high sampling frequency refers to a sampling frequency higher than a threshold frequency. The threshold frequency may be a default value, or determined manually by the user, or determined by the processing device 120 according to data analysis. For example, the threshold frequency may be determined according to at least one time-varying dimension to be analyzed. By way of example only, the time-varying dimension may be related to the respiratory motion of the object, and the respiratory cycle of the object is close to 0.75 seconds. To capture dynamic information related to the respiratory motion of the object, the sampling frequency may need to be greater than the threshold frequency of 1 / 0.75 Hertz (Hz). As another example, the threshold frequency may be determined according to actual requirements (e.g., accuracy requirements), experience, data models, etc. In some embodiments, the auxiliary signal may also be referred to as a navigation signal.

[0087] The imaging signal may include high-spatial-resolution image data related to at least one spatial-varying dimension of the object (or imaging slice position). Exemplary spatial-varying dimensions may involve the slice selection direction, the phase encoding direction, the frequency encoding direction, etc., or any combination thereof. In some embodiments, the imaging signal can be used to estimate at least one spatial basis function related to at least one spatial-varying dimension of the target slice position, which will be described in detail in Figure 10 . In some embodiments, the imaging signal can be obtained by sampling different k-space lines in the k-space.

[0088] The auxiliary signal and the imaging signal can be obtained by any suitable sampling pattern. In some embodiments, the auxiliary signal and the imaging signal can be obtained by radial sampling. The auxiliary signal may correspond to radial lines in the k-space having a constant angle (e.g., 0°, 10°, 20°, 30°, 100°, 180°, etc.). By way of example only, the radial lines at a constant angle in the k-space can be repeatedly sampled at fixed time intervals to obtain the auxiliary signal. For example, as Figure 8 shown, at least two auxiliary signals can be obtained by repeatedly sampling the 0° radial line at each odd reading. As another example, as Figure 9 shown, at least two auxiliary signals can be obtained by repeatedly sampling the 0° radial line once every three reads.

[0089] The imaging signal can correspond to at least two (multiple) radial lines in K-space having different readout angles. In some embodiments, the processing device 120 can obtain the imaging signal by sampling at least two (multiple) radial lines in K-space according to the golden angle radial sampling mechanism. For example, as Figure 8 shown, the readout angles of N imaging signals are 0*θ, 1*θ, 2*θ, 3*θ, 4*θ, …, and N*θ, where N is a positive integer greater than 1, and θ refers to the golden angle, approximately 111.25°. As another example, as Figure 9 shown, the readout angles of the imaging signals are 0*θ, 0*θ, 1*θ, 1*θ, 2*θ, 2*θ, …, N*θ, and N*θ. By adopting the golden angle radial sampling mechanism, multiple radial lines evenly distributed in K-space and covering K-space can be obtained in a relatively short time, which can improve the scanning efficiency and reduce the amount of calculation and calculation time. It should be understood that any other readout angle (e.g., a randomly set readout angle) can be used to sample the imaging signal according to actual needs (e.g., based on requirements regarding scanning time and / or imaging quality).

[0090] In some embodiments, the auxiliary signal and the imaging signal can be obtained by Cartesian sampling. The auxiliary signal can correspond to the same Cartesian line or different Cartesian lines in K-space. In some embodiments, the auxiliary signal can correspond to a Cartesian line passing through the center of K-space in K-space. In some embodiments, the imaging signal can be obtained by Cartesian sampling, while the auxiliary signal can be obtained by repeatedly sampling a specific radial line or spiral line in K-space.

[0091] The auxiliary signal and the imaging signal can be obtained in any sampling order during the MRI scan of the object. In some embodiments, the auxiliary signal and the imaging signal can be alternately acquired during the MRI scan of the object. For example, a first number of imaging signals can be acquired after or before each readout of a second number of auxiliary signals. The first number and the second number can be any positive integer, such as 1, 2, 3, 5, 10, etc. Merely by way of example, referring to Figure 8 it can be seen that one imaging signal can be acquired after each readout of one auxiliary signal. In this case, the ratio of the count of the imaging signals to the count of the auxiliary signals acquired in operation 601 can be 1:1. As another example, referring to Figure 9 it can be seen that two imaging signals can be acquired after each readout of one auxiliary signal. In this case, the ratio of the count of the imaging signals to the count of the auxiliary signals acquired in operation 601 can be 2:1.

[0092] In some embodiments, the first quantity and the second quantity can be set according to actual needs. For example, the sampling frequency of the auxiliary signal needs to be greater than the threshold frequency and / or sufficient imaging signals need to be acquired for image reconstruction. In some embodiments, the ratio of the first quantity to the second quantity can be related to the type of the object to be imaged. For example, for imaging of a patient's heart, the ratio of the first quantity to the second quantity can be equal to 1:1. As another example, for imaging of organs other than the heart (e.g., arm, knee), the ratio of the first quantity to the second quantity can be equal to 10:1.

[0093] In some embodiments, the MRI pulse sequence for collecting (acquiring) the auxiliary signal and the imaging signal can be any type of MRI pulse sequence, such as a spin echo sequence, a gradient echo sequence, a diffusion sequence, an inversion recovery sequence, or another type of MRI pulse sequence as Figure 2 shown, or any combination thereof. The MRI pulse sequence can be specifically designed to implement the SMS technique and the multi-tasking technique. As described above, to implement the multi-tasking technique, the auxiliary signal can be collected by repeatedly sampling at least one subset of the k-space at a high sampling frequency. To implement the SMS technique, the MRI scanner can include at least one (type of) excitation pulse (e.g., a multi-band radiofrequency pulse), which is used to simultaneously excite slice positions, and can also include a phase modulation scheme, which is used to facilitate the separation of slices (slice position image data) from the aliased image data in image reconstruction.

[0094] During the application of the MRI pulse sequence, phase modulation can be applied to at least one slice position such that at least two slice positions have different phases during the readout of at least one imaging signal. As used herein, if at least two of the multiple slice positions have different phases, the multiple slice positions can be considered to have different phases. In other words, during the readout of at least one imaging signal, the phases of the slice positions can be partially or completely different from each other. In some embodiments, during the application of the MRI pulse sequence, the phase modulation can be applied to each slice position or a partial slice position.

[0095] For example, phase modulation can be applied to at least one slice position such that during the readout of each imaging signal, the at least one slice position has a random phase. As Figure 8 shown, phase modulation can be applied to slice position 2 such that slice position 2 has a random phase during the readout of each imaging signal. As another example, phase modulation can be applied to the at least one slice position such that during the readout of consecutive imaging signals, the phase of the at least one slice position alternates between a first angle and a second angle, where the second angle is different from the first angle. Figure 9As shown, phase modulation can be applied to slice position 2 such that during the readout of the continuous imaging signal, the phase of the slice position 2 alternates between 0 degrees and 180 degrees. As yet another example, the slice positions can include three slice positions, and phase modulation can be applied to two of the three slice positions such that the phase of one slice (e.g., the first slice) position is always 0°; the phase of one slice (e.g., the second slice) position periodically ranges from -120° to 0° to 120°; and the phase of one slice (e.g., the third slice) position periodically ranges from -240° to 0° to 240°. Based on the phase differences between the slice positions, the systems and methods disclosed herein can readily resolve the imaging signals of the slice positions to generate an image of a single slice position without performing an additional reference scan on the subject.

[0096] In some embodiments, phase modulation can be performed by applying a phase-modulated radiofrequency excitation pulse, a phase-modulated gradient, or a combination thereof. For example, a phase-modulated radiofrequency excitation pulse can be applied to excite a slice position and modulate the phase of at least one slice position. As another example, after exciting the slice position and before reading out the imaging signal, a phase-modulated gradient can be applied by the gradient coils (e.g., the Z coils) of the MRI scanner along the slice encoding direction, wherein the phase-modulated gradient can cause a phase difference between the slice positions during the readout of the imaging signal.

[0097] In 602, for each of one or more target slice positions of at least two slice positions, the processing device 120 (e.g., the generation module 502) can generate one or more target images of the target slice position based on the auxiliary signal and the imaging signal.

[0098] The target slice positions can include all or part of the slice positions. For example, the target slice positions can be selected from the slice positions by a user (e.g., a doctor, a technician) or according to the default settings of the MRI system 100. As another example, the processing device 120 can select the target slice positions from the slice positions based on data analysis. By way of example only, among at least two cardiac slice positions, the target slice positions can include the slice positions that experience significant contraction and relaxation.

[0099] The target image at the target slice position may include a static image and / or a dynamic image at the target slice position. In some embodiments, the static image may correspond to a specific motion phase of the object. For example, the static image may include a slice image of a cardiac slice corresponding to a specific cardiac phase, or an image of a lung slice corresponding to a specific respiratory phase. The dynamic image may reflect the dynamic information of the target slice position along the time-varying dimension. In some embodiments, the dynamic image may include a series of slice images that vary over time, such as at least two (multiple) slice images of the target slice position corresponding to at least two motion phases of the object. For example, the dynamic image may reflect the cardiac motion of a cardiac slice during the cardiac cycle and include at least two (multiple) images of the cardiac slice corresponding to at least two (multiple) cardiac phases during the heartbeat cycle.

[0100] In some embodiments, the processing device 120 may generate the target image at the target slice position by performing the process 1000 as Figure 10 described. In some embodiments, the processing device 120 may generate one or more target images for each slice position of the object and generate one or more target images of the object by combining the target images for each slice position. By way of example only, a patient's heart may include 10 cardiac slices and the patient's cardiac cycle may include 4 cardiac phases. The processing device 120 may generate a 2D static image corresponding to the end-diastolic phase for each cardiac slice based on the auxiliary signal and the imaging signal, and further generate a 3D static image of the patient's heart corresponding to the end-diastolic phase by combining the 2D static images of the 10 cardiac slices. As another example, the processing device 120 may generate a dynamic image reflecting the cardiac motion during the cardiac cycle for each cardiac slice and further generate a 4D dynamic image of the patient's heart by combining the dynamic images of the 10 cardiac slices.

[0101] The present application provides an SMS multi-task imaging technique that combines the advantages of SMS technology and multi-task technology. For example, it can track multi-dimensional dynamic information with higher scanning efficiency. Compared with traditional multi-task technology, the SMS multi-task imaging technique of the present invention can shorten the scanning time and / or improve the accuracy of dynamic tracking for some parts with no obvious motion (e.g., the slice position near the apex of the heart where the cardiac contraction and relaxation motions are not obvious). Compared with SMS technology, the SMS multi-task imaging technique uses phase modulation of the slice position for slice separation, without the need to obtain a reference image through additional scanning, and avoids errors that may occur during additional scanning.

[0102] It should be noted that the above description of process 600 is provided for illustrative purposes only and is not intended to limit the scope of the present application. Those of ordinary skill in the art can make various changes and modifications based on the description of the present application. However, these changes and modifications do not depart from the scope of the present application. In some embodiments, process 600 can be completed with one or more additional operations not described, and / or without using one or more operations discussed. For example, process 600 can include an additional operation of sending the target image to a terminal device (e.g., the doctor's terminal device 140) for display.

[0103] Figure 7 is a schematic diagram of an exemplary MRI pulse sequence 700 for implementing multi-tasking technology. Conventionally, MRI signals at at least two slice positions are obtained by applying an MRI pulse sequence to each of the at least two slice positions separately. For example, the MRI pulse sequence 700 can be applied by an MRI scanner (e.g., MRI scanner 110) to a single slice position to obtain at least two auxiliary signals and at least two imaging signals at the slice position through radial sampling. As Figure 7 shown, an imaging signal is obtained after each readout of an auxiliary signal; the auxiliary signals are obtained by repeatedly sampling the 0° radial line; the imaging signals are obtained by sampling at least two radial lines in the K space according to the golden angle radial sampling mechanism.

[0104] Figure 8 is a schematic diagram of an exemplary MRI pulse sequence 800 for implementing SMS multi-tasking technology according to some embodiments of the present application. As Figure 8 shown, the MRI pulse sequence 800 includes at least two excitation pulses, and the at least two excitation pulses can simultaneously excite slice positions 1 and 2 of the object to obtain at least two auxiliary signals and at least two imaging signals at slice positions 1 and 2 through radial sampling. An imaging signal is obtained after each readout of an auxiliary signal, the auxiliary signals are obtained by repeatedly sampling the 0° radial line, and the imaging signals are obtained by sampling at least two radial lines in the K space according to the golden angle radial sampling time schedule. During the application of the MRI pulse sequence 800, random phase modulation is applied to slice position 2 such that slice position 2 has different phases during the readout of each imaging signal. The phase of slice position 1 is always equal to 0°. During the readout of each imaging signal, slice position 2 has a random phase.

[0105] Figure 9 is a schematic diagram of an exemplary MRI pulse sequence 900 for implementing SMS multi-tasking technology according to some embodiments of the present application. The MRI pulse sequence 900 is similar to the MRI pulse sequence 800 but has certain components or features different. As Figure 9As shown, two imaging signals are acquired after each acquisition of an auxiliary signal. The auxiliary signal is acquired by repeatedly sampling the 0° radial line, and at least two radial lines are sampled in the K space according to the golden angle radial sampling mechanism to obtain the imaging signals. During the application of the MRI pulse sequence 900, a phase modulation scheme is applied to the slice position 2 such that during the acquisition of consecutive imaging signals, the phase of the slice position 2 alternates between 0 degrees and 180 degrees. The phase of the slice position 1 is always equal to 0°.

[0106] It should be noted that Figure 8 and Figure 9 the exemplary MRI pulse sequence and its description shown are provided for illustrative purposes only and are not intended to limit the scope of the present application. Those of ordinary skill in the art can make various changes and modifications according to the description of the present application. However, these changes and modifications do not depart from the scope of the present application. In some embodiments, any other phase modulation scheme different from the Figure 8 and Figure 9 phase modulation scheme shown in can be used to modulate the phase of the slice position. Additionally or alternatively, the readout angle of the slice position can be different from that shown in Figure 8 or Figure 9 . Furthermore, the sampling order of the auxiliary signal and the imaging signal and / or the counting of the imaging signal can be modified according to actual needs. For example, the imaging signal can be acquired by each odd readout, and the auxiliary signal can be acquired by each even readout. As another example, the ratio of the counting of the auxiliary signal to the counting of the imaging signal can be equal to 1:5, 1:8, 1:10 or any other suitable value.

[0107] Figure 10 is a flowchart of an exemplary process for generating one or more target images of a target slice position shown in some embodiments of the present application. In some embodiments, the process 1000 can be executed by the MRI system 100. For example, the process 1000 can be implemented as a set of instructions (e.g., an application program) stored in a storage device (e.g., the storage device 130, the storage device 320, and / or the storage device 490). In some embodiments, the processing device 120 (e.g., the processor 310 of the computing device 300, the CPU 440 of the mobile device 400, and / or Figure 5 one or more modules shown in) can execute the set of instructions and can accordingly be instructed to execute the process 1000. In some embodiments, one or more operations of the process 1000 can be executed to implement at least a part of the operation 602 as described in Figure 6 .

[0108] In some embodiments, the target image at the target slice position has multiple dimensions (e.g., spatial variation dimension and temporal variation dimension), and can be represented by a multi-dimensional tensor. For example, the target image can be represented as an (X + 1)-dimensional image tensor (or array), where the first tensor dimension can index the spatial variation dimension, and each of the other X tensor dimensions can index the temporal variation dimension. X is a positive integer equal to the number of temporal variation dimensions.

[0109] A low-rank tensor image model can be used to resolve multiple overlapping dynamics (e.g., temporal variation dimensions). For example, based on the low-rank tensor image model, the target image can be represented by the product of a core tensor and (X + 1) basis matrices. The core tensor can control the interaction between the basis matrices. The (X + 1) basis matrices can include a spatial factor matrix and X temporal factor matrices. The spatial factor matrix can include one or more spatial basis functions related to the spatial variation dimension of the target slice position. Each of the X temporal factor matrices can correspond to one of the temporal variation dimensions and include one or more temporal basis functions related to the corresponding temporal variation dimension. To generate the target image, it may be necessary to determine the spatial basis functions, temporal basis functions, and core tensor at the target slice position by performing the following operations based on the auxiliary signal and the imaging signal.

[0110] In 1001, the processing device 120 (e.g., the generation module 502) can determine the temporal basis functions related to the temporal variation dimension of the target slice position based on the auxiliary signal.

[0111] The determined temporal basis functions can include one or more temporal basis functions related to each temporal variation dimension. For example, the temporal basis functions can include one or more cardiac temporal basis functions related to the cardiac motion of the object (or target slice position), one or more respiratory temporal basis functions related to the respiratory motion of the object (or target slice position), one or more T1 recovery temporal basis functions related to the T1 relaxation of the object (or target slice position), etc., or any combination thereof. The temporal basis functions related to the temporal variation dimension can reflect the dynamic information along the temporal variation dimension and include high temporal resolution information.

[0112] In some embodiments, for different target slice positions, if the target slice positions have the same or similar dynamic changes along the temporal variation dimension, the temporal basis functions related to the temporal variation dimension can be the same. By way of example only, different cardiac slices can share the same cardiac temporal basis functions because they follow similar motion laws during the cardiac cycle. In this case, operation 1001 may only need to be performed once to determine the cardiac temporal basis functions for the cardiac slices, and the cardiac temporal basis functions can be used to generate the target images of different cardiac slices.

[0113] In some embodiments, the processing device 120 may determine the time basis functions of the time-varying dimensions and the core tensors as described above based on the auxiliary signals obtained in operation 601. For example, the processing device 120 may construct a first optimization function that is related to the undersampled auxiliary data (e.g., the auxiliary signals obtained in operation 601), a low-rank tensor representing the full-sampled auxiliary signal to be obtained, and matrices corresponding to each time-varying dimension. The matrices corresponding to the time-varying dimensions may include rows indexing the time-varying dimension and columns indexing the other time-varying dimensions. The processing device 120 may determine the low-rank tensor representing the full-sampled auxiliary signal by solving the first optimization function. Based on the low-rank tensor, the processing device 120 may determine the time basis functions and the core tensors of each time-varying dimension. For example, the processing device 120 may use an explicit strategy to recover the time basis functions and the core tensors based on the low-rank tensor according to the high-order singular value decomposition (HOSVD) algorithm.

[0114] In 1002, the processing device 120 (e.g., the generation module 502) may determine the spatial basis functions related to the spatial-varying dimensions of the target slice positions based on the time basis functions and the imaging signals.

[0115] The spatial basis functions of the target slice positions may include high spatial resolution information along the spatial-varying dimensions. For example, the spatial basis functions may reflect the relationship between the pixel information of the target slice positions in the image domain and the spatial information in the physical domain. In some embodiments, the spatial basis functions may be represented as basis images including high spatial resolution information. Different spatial basis functions may be represented as basis images including different high spatial resolution information.

[0116] In some embodiments, the processing device 120 may construct a second optimization function related to the spatial basis functions. The second optimization function may include the imaging signals and the time basis functions. The processing device 120 may further determine the spatial basis functions by solving the second optimization function. Only as an example, if the MRI pulse sequence 800 in Figure 8 is used to acquire the auxiliary signals and the imaging signals of the object, the processing device 120 may determine the spatial basis functions of slice positions 1 and 2 according to the second optimization function shown in the following equation (1):

[0117]

[0118] where, represents the optimal spatial factor matrix of slice position 1 determined by solving equation (1), represents the optimal spatial factor matrix of slice position 2 determined by solving equation (1), U1 represents the spatial factor matrix of slice position 1, U2 represents the spatial factor matrix of slice position 2, and d imgrepresents the imaging signal (i.e., the gray line as shown in Figure 8 ), Ω represents the undersampling operator, F represents the Fourier transform operator, S1 represents the coil sensitivity map corresponding to slice position 1, S2 represents the coil sensitivity map corresponding to slice position 2, Φ represents the time basis functions of slice positions 1 and 2 (e.g., in the form of one or more time factor matrices), P represents the random phase operator applied to slice position 2, λ represents the regularization parameter, and λR(U1,U2) represents the constraint term related to the spatial factor matrices of slice positions 1 and 2 (which can be omitted under certain conditions). In some embodiments, where θ i represents the random phase applied to slice position 2, and P i represents the random phase operator applied to slice position 2. The determined and may respectively include the spatial basis functions of slice position 1 and slice position 2.

[0119] As another example, if the MRI pulse sequence 900 in Figure 9 is used to acquire the auxiliary signal and the imaging signal of the object, the processing device 120 can determine the spatial basis functions of slice positions 1 and 2 according to the following equations (2) and (3) respectively:

[0120]

[0121]

[0122] where d img + represents the imaging signal acquired when the phases of slice positions 1 and 2 are both 0°, and d img - represents the imaging signal acquired when the phases of slice positions 1 and 2 are 0° and 180° respectively, λ represents the regularization parameter, λR(U1) represents the constraint term related to the spatial factor matrix of slice position 1 (which can be omitted under certain conditions), and λR(U2) represents the constraint term related to the spatial factor matrix of slice position 2 (which can be omitted under certain conditions).

[0123] In some embodiments, coil sensitivity maps corresponding to slice positions 1 and 2 can be determined based on reference scans performed at slice positions 1 and 2. For example, a reference slice image of slice position 1 can be obtained by performing a reference scan on slice position 1, a reference slice image of slice position 2 can be obtained by performing a reference scan on slice position 2, and the coil sensitivity maps can be determined based on the reference slice images of slice positions 1 and 2. In some embodiments, the coil sensitivity maps corresponding to slice positions 1 and 2 can be determined based on imaging signals without performing a reference scan on the subject. Due to the phase modulation performed at slice position 2, reference slice images of slice positions 1 and 2 can be generated based on the imaging signals. By way of example only, the first set of image data corresponding to slice position 1 and the second set of image data corresponding to slice position 2 can be determined by performing a linear combination (e.g., addition and subtraction) on d img + and d img - The reference slice image of slice position 1 can be reconstructed based on the first set of image data, the reference slice image of slice position 2 can be reconstructed based on the second set of image data, and then the coil sensitivity maps can be determined based on the reference slice images of slice positions 1 and 2.

[0124] In 1003, the processing device 120 (e.g., the generation module 502) can generate one or more target images of the target slice position based on the temporal basis function and the spatial basis function of the target slice position.

[0125] As described above, a target image with multi-dimensional target slice positions can be represented by a multi-dimensional tensor, which can be determined based on a spatial factor matrix (including spatial basis functions) of the target slice positions and a temporal factor matrix (including temporal basis functions) of the target slice positions. For example, when the temporal basis functions and spatial basis functions are available, the processing device 120 can generate a target image of the target slice positions with multiple temporal variation dimensions by determining the product between the temporal factor matrix, the spatial factor matrix, and the core tensor, where the temporal factor matrix includes temporal basis functions, the spatial factor matrix includes spatial basis functions, and the core tensor controls the interaction between the temporal factor matrix and the spatial factor matrix. In some embodiments, the processing device 120 can generate a target image of the target slice positions corresponding to a specific temporal variation dimension based on the temporal factor matrix corresponding to the specific temporal variation dimension and the spatial factor matrix including spatial basis functions. For example, the processing device 120 can generate a dynamic image of a heart slice by determining the product between the spatial factor matrix, the temporal factor matrix, and the core tensor, where the spatial factor matrix includes the spatial basis functions of the heart slice, the temporal factor matrix includes the temporal basis functions related to the heart movement, and the core tensor can control the interaction between the spatial factor matrix and the temporal factor matrix. As another example, the processing device 120 can also extract a static image of the heart slice corresponding to a specific heart phase from the dynamic image of the heart slice.

[0126] It should be noted that the above description of the process 1000 is provided for illustrative purposes only and is not intended to limit the scope of the present application. Those of ordinary skill in the art can make various changes and modifications according to the description of the present application. However, these changes and modifications do not depart from the scope of the present application. In some embodiments, the process 1000 can be completed with one or more additional operations not described, and / or without using one or more operations discussed. In some embodiments, the equations provided above are illustrative examples and can be modified in various ways. For example, one or more coefficients in the equations can be omitted, and / or the equations can further include one or more additional coefficients.

[0127] In some embodiments, a target image of at least two target slice positions can be generated simultaneously by performing a process similar to the process 1000. The target slice positions can have the same temporal basis functions, and the processing device 120 can determine the temporal basis functions of the target slice positions by performing operation 1001. The processing device 120 can also jointly determine the spatial basis functions of the target slice positions according to, for example, equation (1) as described above. Then, for each target slice position, the processing device 120 can generate a target image of the target slice position based on the temporal basis function and the spatial basis function of the target slice position.

[0128] The basic concepts have been described above. Obviously, for those of ordinary skill in the art after reading this application, the above invention disclosure is only for illustration and does not constitute a limitation to this application. Various modifications, improvements and corrections may occur, and these modifications, improvements and corrections are for those skilled in the art, although not explicitly stated herein. Such modifications, improvements and corrections are proposed in this application, so such modifications, improvements and corrections still fall within the spirit and scope of the exemplary embodiments of this application.

[0129] At the same time, this application uses specific terms to describe the embodiments of this application. For example, "an embodiment", "one embodiment", and / or "some embodiments" mean a certain feature, structure or characteristic related to at least one embodiment of this application. Therefore, it should be emphasized and noted that the "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned two or more times in different positions in this specification are not necessarily referring to the same embodiment. In addition, certain features, structures or characteristics in one or more embodiments of this application can be appropriately combined.

[0130] In addition, those of ordinary skill in the art can understand that various aspects of this application can be illustrated and described by several patentable types or situations, including any new and useful process, machine, product or composition of matter, or any new and useful improvement thereof. Therefore, various aspects of the present invention can be implemented entirely by hardware, entirely by software (including firmware, resident software, microcode, etc.) or a combination of software and hardware implementation, and the software and hardware implementation are generally referred to as "units", "modules" or "systems" herein. In addition, various aspects of this application can take the form of a computer program product, which is embodied in one or more computer-readable media, and computer-readable program code is embodied on the computer-readable media.

[0131] A computer-readable signal medium may include a propagated data signal containing computer program code therein, for example, on a baseband or as part of a carrier wave. Such propagated signals can have various forms, including electromagnetic form, optical form, etc. or any suitable combination. A computer-readable signal medium can be any computer-readable medium other than a computer-readable storage medium, and this medium can be connected to an instruction execution system, apparatus or device to communicate, propagate or transmit a program for use. The program code located on the computer-readable signal medium can be propagated through any suitable medium, including radio, cable, fiber optic cable, radio frequency, etc., or any combination of the above media.

[0132] The computer program code for operating various aspects of the present application can be written in any combination of one or more programming languages, including object-oriented programming languages such as Java, Scala, Smalltalk, Eiffel, JADE, Emerald, C++, C#, VB.NET, Python, etc.; traditional procedural programming languages such as the "C" programming language, VisualBasic, Fortran2003, Perl, COBOL2002, PHP, ABAP; dynamic programming languages such as Python, Ruby, and Groovy, or other programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer as a stand-alone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the latter case, the remote computer can be connected to the user's computer through any type of network connection, including a local area network (LAN) or a wide area network (WAN), or can be connected to an external computer (e.g., through the Internet using an Internet service provider) or in a cloud computing environment, or provided as a service, such as software as a service (SaaS).

[0133] In addition, unless clearly stated in the claims, the order of the processing elements and sequences, the use of numerical letters, or the use of other names in the present application is not used to limit the order of the processes and methods of the present application. Although some currently useful embodiments of the invention are discussed through various examples in the above disclosure, it should be understood that such details are for illustrative purposes only. The additional claims are not limited to the disclosed embodiments. On the contrary, the claims are intended to cover all modifications and equivalent combinations that conform to the essence and scope of the embodiments of the present application. For example, although the implementation of the various components described above can be realized in a hardware device, it can also be realized as a software-only solution, for example, by installation on an existing server or mobile device.

[0134] Similarly, it should be noted that, in order to simplify the description of the present application disclosure and thus help the understanding of one or more embodiments of the invention, in the foregoing description of the embodiments of the present application, sometimes multiple features are grouped into one embodiment, drawing, or description thereof. However, this method of the present application should not be construed as reflecting an intention that the claimed subject matter requires more features than those explicitly recited in each claim. On the contrary, the subject matter of the invention should have fewer features than the above single embodiment.

[0135] Numbers used to describe and claim certain embodiments of the present application in terms of expression quality or characteristics should be understood to be modified in certain cases by the terms "about", "approximate" or "substantially". For example, unless otherwise specified, "about", "approximate" or "substantially" may represent a variation in the range of ±1%, ±5%, ±10% or ±20% of the value it describes. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may vary according to the characteristics required by individual embodiments. In some embodiments, the numerical parameters should take into account the specified significant digits and adopt the method of retaining the general number of digits. Although the numerical ranges and parameters used to confirm the breadth of their scope in some embodiments of the present application are approximate values, in specific embodiments, such numerical settings are made as precise as possible within the feasible range.

[0136] Finally, it should be understood that the embodiments described in the present application are only used to illustrate the principles of the embodiments of the present application. Other variations may also fall within the scope of the present application. Therefore, by way of example and not limitation, alternative configurations of the embodiments of the present application may be considered to be consistent with the teachings of the present application. Accordingly, the embodiments of the present application are not limited to the embodiments explicitly introduced and described in the present application.

Claims

1. A method for magnetic resonance imaging, comprising: Acquiring at least two auxiliary signals and at least two imaging signals by simultaneously applying an MRI pulse sequence to at least two slice positions of an object; For each of at least one target slice position among the at least two slice positions, generating at least one target image of the target slice position based on the at least two auxiliary signals and the at least two imaging signals; During the application of the MRI pulse sequence, phase modulation is applied to at least one of the at least two slice positions such that the at least two slice positions have different phases during the readout of at least one imaging signal, and applying the phase modulation includes applying a phase-modulated radiofrequency excitation pulse and / or a phase-modulated gradient.

2. The method according to claim 1, wherein For each of at least one target slice position among the at least two slice positions, generating at least one target image of the target slice position includes: For each of at least one target slice position, Determining at least one temporal basis function based on the at least two auxiliary signals, the at least one temporal basis function being related to at least one temporal variation dimension of the target slice position; Determining at least one spatial basis function based on the at least one temporal basis function and the at least two imaging signals, the at least one spatial basis function being related to at least one spatial variation dimension of the target slice position; and Generating the at least one target image of the target slice position based on the at least one temporal basis function and the at least one spatial basis function.

3. The method according to claim 2, wherein The determining at least one spatial basis function based on the at least one temporal basis function and the at least two imaging signals includes: Constructing an optimization function related to the at least one spatial basis function, the optimization function including the at least two imaging signals and the at least one temporal basis function; and Determining the at least one spatial basis function by solving the optimization function.

4. The method according to claim 1, wherein The at least two auxiliary signals are related to at least one of cardiac motion, respiratory motion, T1 relaxation, T2 relaxation, chemical exchange saturation transfer, contrast agent dynamics, T1ρ contrast, molecular diffusion, or natural time.

5. The method according to claim 1, characterized in that The at least two auxiliary signals correspond to the same k-space line in k-space.

6. The method according to claim 1, characterized in that, The at least two auxiliary signals and the at least two imaging signals are acquired by radial sampling, and the at least two auxiliary signals correspond to radial lines with a constant angle in k-space.

7. The method according to claim 1, characterized in that The method for acquiring the at least two auxiliary signals and the at least two imaging signals is Cartesian sampling, and the at least two auxiliary signals correspond to Cartesian lines passing through the k-space center in k-space.

8. The method according to claim 1, wherein The phase modulation is applied to the at least one slice position such that the at least one slice position has a random phase during the readout of each imaging signal.

9. The method according to claim 1, wherein The phase modulation is applied to the at least one slice position such that during the readout of consecutive imaging signals, the phase of the at least one slice position alternates between a first angle and a second angle different from the first angle.

10. A magnetic resonance imaging system, characterized in that, The system includes: An acquisition module for obtaining at least two auxiliary signals and at least two imaging signals collected by simultaneously applying an MRI pulse sequence to at least two slice positions of an object; and A generation module for generating at least one target image of a target slice position for each of at least one target slice position among the at least two slice positions, based on the at least two auxiliary signals and the at least two imaging signals, wherein during the application of the MRI pulse sequence, phase modulation is applied to at least one of the at least two slice positions such that the at least two slice positions have different phases during the readout of at least one imaging signal, and applying the phase modulation includes applying a phase-modulated radiofrequency excitation pulse and / or a phase-modulated gradient.

Images