Magnetic resonance imaging system and implant positioning method thereof

Abstract

The present application provides a magnetic resonance imaging system and a method for positioning an implant thereof, and a non-transitory computer-readable storage medium. The method for positioning an implant of the magnetic resonance imaging system includes executing a first scanning sequence to obtain raw image data, and reconstructing an edge image of the implant based on the raw image data, wherein the first scanning sequence includes a radio frequency excitation pulse, and a first layer selection gradient pulse corresponding to the radio frequency excitation pulse, and the frequency of the radio frequency excitation pulse has a preset offset compared to the center frequency, a radio frequency refocusing pulse, and a second layer selection gradient pulse corresponding to the radio frequency refocusing pulse, and the direction of the second layer selection gradient pulse is opposite to the direction of the first layer selection gradient pulse.

Description

Technical Field

[0001] The present invention relates to medical imaging technology, and more particularly to a positioning method for an implant of a magnetic resonance imaging system, a display method, a magnetic resonance imaging system, and a non-transitory computer-readable storage medium. Background Art

[0002] Magnetic resonance imaging (MRI) is a medical imaging modality that can obtain images of the human body without using X-rays or other ionizing radiation. MRI uses a magnet with a strong magnetic field to generate a main magnetic field B0. When the part of the human body to be imaged is positioned in the main magnetic field B0, the nuclear spins associated with the hydrogen nuclei in the human tissue are polarized, so that the tissue of the part to be imaged generates a longitudinal magnetization vector on a macroscopic level. When a radio frequency field B1 that intersects with the direction of the main magnetic field B0 is applied, the direction of proton rotation changes, so that the tissue of the part to be imaged generates a transverse magnetization vector on a macroscopic level. After the radio frequency field B1 is removed, the transverse magnetization vector decays in a spiral shape until it returns to zero, and a free induction decay signal is generated during the decay process. The free induction decay signal can be collected as a magnetic resonance signal, and the tissue image of the part to be imaged can be reconstructed based on the collected signal. The gradient system is used to transmit a layer selection gradient pulse, a phase encoding gradient pulse, and a frequency encoding gradient pulse (also called a readout gradient pulse) to provide three-dimensional position information for the above-mentioned magnetic resonance signal to achieve image reconstruction.

[0003] In recent years, more and more people choose to implant medical, orthopedic, plastic and other devices in their bodies. For implants in the human body, such as pacemakers, orthopedic implants, puncture equipment, etc., before scanning, it is usually necessary to obtain parameters related to the implant through verbal inquiries or case inquiries, such as the model, size, and location of the implant. However, for unconscious or unconscious subjects, the relevant parameters of the implant cannot be obtained through the above methods. When it is impossible to know whether there is an implant in the subject and the location of the implant, it will cause certain impacts or difficulties to the magnetic resonance imaging.

[0004] During the MRI scan, the presence of implants will cause the main magnetic field to be uneven, which will result in partial missing images in the final image. However, since some tissues of the human body contain air, the presence of air pockets will also cause partial missing images in the MRI image. Therefore, it is not possible to distinguish whether there is an implant in the subject through the image. Summary of the invention

[0005] The present invention provides a positioning method for an implant of a magnetic resonance imaging system, a display method, a magnetic resonance imaging system, and a non-transitory computer-readable storage medium.

[0006] An exemplary embodiment of the present invention provides a method for positioning an implant in a magnetic resonance imaging system, the positioning method comprising executing a first scanning sequence to acquire original image data, and reconstructing an edge image of the implant based on the original image data, wherein the first scanning sequence comprises: a radio frequency excitation pulse and a first layer selection gradient pulse corresponding to the radio frequency excitation pulse, and a radio frequency refocusing pulse and a second layer selection gradient pulse corresponding to the radio frequency refocusing pulse, wherein the frequency of the radio frequency excitation pulse has a preset offset compared to the center frequency, and the direction of the second layer selection gradient pulse is opposite to that of the first layer selection gradient pulse.

[0007] Specifically, the radio frequency excitation pulse is used to excite the marginal tissue of the implant.

[0008] Specifically, the preset offset is determined based on relevant parameters of the implant.

[0009] Specifically, reconstructing the edge image of the implant includes reconstructing the original image data based on the coil sensitivity map, wherein the original image data includes data received by multiple radio frequency receiving channels.

[0010] Specifically, the positioning method further includes determining whether the detected object contains an implant based on a difference between one-dimensional signals or images acquired by a second scanning sequence and a third scanning sequence, wherein the frequency encoding directions of the second scanning sequence and the third scanning sequence are different.

[0011] Specifically, determining whether the object under inspection contains an implant includes executing the second scanning sequence to obtain a first image or a first group of one-dimensional signals of the object under inspection, and the second scanning sequence includes a first frequency encoding direction; executing the third scanning sequence to obtain a second image or a second group of one-dimensional signals of the object under inspection, and the third scanning sequence includes a second frequency encoding direction, and the second frequency encoding direction is perpendicular to the first frequency encoding direction; and determining whether the object under inspection contains an implant based on the difference between the first image and the second image or the difference between the first group of one-dimensional signals and the second group of one-dimensional signals.

[0012] Specifically, obtaining a first group of one-dimensional signals of the detected object includes scanning the detected object along the first frequency encoding direction, and storing the acquired first group of image data in the K space; selecting a row or a column of image data corresponding to a specific frequency in the K space; and performing Fourier transform on the row or the column of image data to obtain the first group of one-dimensional signals.

[0013] Specifically, obtaining the second group of one-dimensional signals of the detected object includes determining a specific phase, wherein the specific phase corresponds to the same row or column in the K space with the specific frequency; scanning the detected object along the second frequency encoding direction and the specific phase to obtain image data of the same row or column as the second group of image data; and performing Fourier transform on the second image data to obtain the second group of one-dimensional signals.

[0014] Specifically, based on the difference between the first image and the second image or the difference between the first group of one-dimensional signals and the second group of one-dimensional signals, judging whether the detected object contains an implant includes determining that the detected object contains an implant when the difference between the first image and the second image exceeds a preset threshold, or the difference between the first group of one-dimensional signals and the second group of one-dimensional signals exceeds a preset threshold.

[0015] Specifically, the positioning further includes indicating predicted values ​​of magnetic resonance imaging system parameters associated with the implant and a safe state of one or more of the parameters after completing the imaging scan.

[0016] An exemplary embodiment of the present invention further provides a non-transitory computer-readable storage medium for storing a computer program, which, when executed by a computer, causes the computer to execute the above-mentioned method for positioning an implant for a magnetic resonance imaging system.

[0017] An exemplary embodiment of the present invention also provides a display method, which includes a first option related to the detection of implant position confirmation, the first option is used to execute a first scanning sequence to acquire original image data, and reconstruct an edge image of the implant based on the original image data, wherein the first scanning sequence includes: a radio frequency excitation pulse and a first layer selection gradient pulse corresponding to the radio frequency excitation pulse, and a radio frequency refocusing pulse and a second layer selection gradient pulse corresponding to the radio frequency refocusing pulse, wherein the frequency of the radio frequency excitation pulse has a preset offset compared to the center frequency, and the direction of the second layer selection gradient pulse is opposite to the direction of the first layer selection gradient pulse.

[0018] Specifically, the display method also includes a second option related to the detection of whether an implant exists, and the second option is used to execute the second scanning sequence to obtain a first image or a first group of one-dimensional signals of the object to be detected, and the second scanning sequence includes a first frequency encoding direction; execute the third scanning sequence to obtain a second image or a second group of one-dimensional signals of the object to be detected, and the third scanning sequence includes a second frequency encoding direction, and the second frequency encoding direction is perpendicular to the first frequency encoding direction; and based on the difference between the first image and the second image or the difference between the first group of one-dimensional signals and the second group of one-dimensional signals, determine whether the object to be detected contains an implant.

[0019] An exemplary embodiment of the present invention also provides a magnetic resonance imaging system, the system includes an implant positioning device, and the implant positioning device includes a control module and a reconstruction module, the control module is used to execute a first scanning sequence to obtain original image data, wherein the first scanning sequence includes: a radio frequency excitation pulse and a first layer selection gradient pulse corresponding to the radio frequency excitation pulse, and a radio frequency refocusing pulse and a second layer selection gradient pulse corresponding to the radio frequency refocusing pulse, and the frequency of the radio frequency excitation pulse has a preset offset compared to the center frequency, and the direction of the second layer selection gradient pulse is opposite to the direction of the first layer selection gradient pulse, and the reconstruction module is used to reconstruct the edge image of the implant based on the original image data.

[0020] Specifically, the radio frequency excitation pulse is used to excite the marginal tissue of the implant.

[0021] Specifically, the preset offset is determined based on relevant parameters of the implant.

[0022] Specifically, the reconstruction module is further used to reconstruct the original image data based on the coil sensitivity map, wherein the original image data includes data received by multiple radio frequency receiving channels.

[0023] Specifically, the system further includes a judgment module, which is used to judge whether the object being detected contains an implant based on the difference between the one-dimensional signal or image obtained by the second scanning sequence and the third scanning sequence, wherein the frequency encoding directions of the second scanning sequence and the third scanning sequence are different.

[0024] Specifically, the judgment module includes a first unit, a second unit and a third unit, wherein the first unit is used to execute the second scanning sequence to obtain a first image or a first group of one-dimensional signals of the object to be detected, and the second scanning sequence includes a first frequency encoding direction; the second unit is used to execute the third scanning sequence to obtain a second image or a second group of one-dimensional signals of the object to be detected, and the third scanning sequence includes a second frequency encoding direction, and the second frequency encoding direction is perpendicular to the first frequency encoding direction; the third unit is used to judge whether the object to be detected contains an implant based on the difference between the first image and the second image or the difference between the first group of one-dimensional signals and the second group of one-dimensional signals.

[0025] Specifically, the system further includes an indication module, which is used to indicate the predicted values ​​of the magnetic resonance imaging system parameters related to the implant and the safety status of one or more of the parameters after the imaging scan is completed.

[0026] Other features and aspects will become apparent from the following detailed description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention may be better understood by describing exemplary embodiments of the present invention in conjunction with the accompanying drawings, in which:

[0028] Figure 1 is a schematic diagram of a magnetic resonance imaging system according to some embodiments of the present invention;

[0029] Figure 2 is a schematic diagram of a positioning device 200 for an implant of a magnetic resonance imaging system according to some embodiments of the present invention;

[0030] Figure 3 is a schematic diagram of a first scanning pulse sequence;

[0031] Figure 4 A comparison diagram of the marginal tissue of the implant obtained by scanning based on different first scanning pulses;

[0032] Figure 5 yes Figure 2 The schematic diagram of the judgment module in the positioning device shown;

[0033] Figure 6 is a schematic diagram of a user interface for scanning risk indications in some embodiments of the present invention;

[0034] Figure 7 is a schematic diagram of a user interface for scanning risk indication according to other embodiments of the present invention;

[0035] Figure 8is a flow chart of a method for positioning an implant in a magnetic resonance imaging system according to some embodiments of the present invention;

[0036] Fig. 9 yes Figure 8 A flowchart of determining whether a detected object contains an implant in some embodiments of the positioning method;

[0037] Fig.10 yes Figure 8 A flowchart of determining whether a detected object contains an implant in some other embodiments of the positioning method; and

[0038] Fig.11 It is an image display interface of some embodiments of the present invention. DETAILED DESCRIPTION

[0039] The specific embodiments of the present invention will be described below. It should be noted that in the specific description of these embodiments, in order to provide a concise description, it is impossible for this specification to provide a detailed description of all the features of the actual embodiments. It should be understood that in the actual implementation of any embodiment, just as in the process of any engineering project or design project, in order to achieve the specific goals of the developer and to meet system-related or business-related restrictions, various specific decisions are often made, and this will also change from one embodiment to another. In addition, it can also be understood that although the efforts made in this development process may be complex and lengthy, for ordinary technicians in the field related to the content disclosed by the present invention, some changes such as design, manufacturing or production based on the technical content disclosed in this disclosure are just conventional technical means, and should not be understood as insufficient content of this disclosure.

[0040] Unless otherwise defined, the technical or scientific terms used in the claims and the specification shall have the usual meaning understood by persons with ordinary skills in the technical field to which the invention belongs. The words "first", "second" and similar words used in the patent application specification and the claims of the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "One" or "one" and other similar words do not indicate a quantitative limitation, but indicate the existence of at least one. "Include" or "comprises" and other similar words mean that the elements or objects appearing before "include" or "comprises" include the elements or objects listed after "include" or "comprises" and their equivalent elements, and do not exclude other elements or objects. "Connected" or "connected" and other similar words are not limited to physical or mechanical connections, nor are they limited to direct or indirect connections.

[0041] Figure 1Schematic diagram of an MRI system 100 according to some embodiments of the present invention is shown. Figure 1 As shown, the MRI system 100 includes a scanner 110, a controller unit 120 and a data processing unit 130. The above MRI system 100 is described as an example only. In other embodiments, the MRI system 100 may have a variety of transformation forms as long as it can collect image data from the object being detected.

[0042] The scanner 110 can be used to acquire data of an object 116 to be detected, and the controller unit 120 is coupled to the scanner 110 for controlling the operation of the scanner 110. The scanner 110 may include a main magnet 111, a radio frequency transmitting coil 112, a frequency synthesizer 101, a radio frequency amplifier 103, a transmit / receive switch (T / R switch) 105, a gradient coil system 117, a gradient coil driver 118, and a radio frequency receiving coil 119.

[0043] The main magnet 111 generally includes, for example, an annular superconducting magnet installed in an annular vacuum container. The annular superconducting magnet defines a cylindrical space surrounding the detected object 116. A constant main magnetic field, such as the main magnetic field B0, is generated along the Z direction of the cylindrical space. The MRI system 100 uses the formed main magnetic field B0 to transmit a static magnetic pulse signal to the detected object 116 placed in the imaging space, so that the precession of protons in the detected object 116 is ordered, and a longitudinal magnetization vector is generated.

[0044] The frequency synthesizer 101 is used to generate radio frequency pulses, which may include radio frequency excitation pulses. The radio frequency excitation pulses are amplified by the radio frequency amplifier 103 and applied to the radio frequency transmitting coil 112 through the T / R switch 105, so that the radio frequency transmitting coil 112 transmits a radio frequency magnetic field B1 orthogonal to the main magnetic field B0 to the object 116 to be detected to excite the nuclei in the body of the object 116 to convert the longitudinal magnetization vector into the transverse magnetization vector. When the radio frequency excitation pulse ends, the transverse magnetization vector of the object 116 to be detected gradually returns to zero and generates a free induction decay signal, that is, a magnetic resonance signal that can be collected.

[0045] The RF transmitting coil 112 may be a body coil, which may be connected to the T / R switch 105. By controlling the T / R switch, the body coil may be switched between a transmitting mode and a receiving mode. In the receiving mode, the body coil may be used to receive magnetic resonance signals from the subject 116. In addition, the RF transmitting coil 112 may also be a local coil, such as a head coil.

[0046] In some embodiments, the RF transmitting coil is not limited to the body coil and local coil mentioned in the present application, and may also include various other suitable coil types. The RF receiving coil is also not limited to the body coil, local coil and surface coil mentioned in the present application, and may also include various other suitable coil types.

[0047] The gradient coil system 117 forms a magnetic field gradient in the imaging space to provide three-dimensional position information for the magnetic resonance signal. The magnetic resonance signal can be received by the radio frequency receiving coil 119 or the body coil or local coil in the receiving mode, and the data processing unit 130 can process the received magnetic resonance signal to obtain the required image or image data.

[0048] Specifically, the gradient coil system 117 may include three gradient coils, each of which generates a gradient magnetic field tilted to one of three spatial axes (e.g., X-axis, Y-axis, and Z-axis) perpendicular to each other, and generates a gradient field in each of a slice selection direction, a phase encoding direction, and a frequency encoding direction according to imaging conditions. More specifically, the gradient coil system 117 applies a gradient field in the slice selection direction of the subject 116 to select a slice; and the radio frequency transmission coil 112 transmits a radio frequency excitation pulse to the selected slice of the subject 116 and excites the slice. The gradient coil system 117 also applies a gradient field in the phase encoding direction of the subject 116 to phase encode the magnetic resonance signal of the excited slice. The gradient coil system 117 then applies a gradient field in the frequency encoding direction of the subject 116 to frequency encode the magnetic resonance signal of the excited slice.

[0049] The gradient coil driver 118 is used to respond to the sequence control signal sent by the controller unit 120 to provide appropriate power signals for the three gradient coils respectively.

[0050] The scanner 110 may further include a data acquisition unit 114, which is used to acquire magnetic resonance signals received by the radio frequency surface coil 119 or the body coil. The data acquisition unit 114 may include, for example, a radio frequency preamplifier (not shown), a phase detector (not shown), and an analog / digital converter (not shown), wherein the radio frequency preamplifier is used to amplify the magnetic resonance signals received by the radio frequency surface coil 119 or the body coil, the phase detector is used to perform phase detection on the amplified magnetic resonance signals, and the analog / digital converter is used to convert the phase-detected magnetic resonance signals from analog signals to digital signals. The above-mentioned digitized magnetic resonance signals may be processed by the data processing unit 130, such as calculation and reconstruction, to obtain medical images.

[0051] The data processing unit 130 may include a computer and a storage medium on which a program of a predetermined data processing to be executed by the computer is recorded. The data processing unit 130 may be connected to the controller unit 120 and perform data processing based on a control signal received from the controller unit 120. The data processing unit 130 may also be connected to the data acquisition unit 114 to receive the magnetic resonance signal output by the data acquisition unit 114 in order to perform the above-mentioned data processing.

[0052] The controller unit 120 may include a computer and a storage medium for storing a program executable by the computer. When the computer executes the program, the multiple components of the scanner 110 may perform operations corresponding to the above imaging sequence. The data processing unit 130 may also perform predetermined data processing.

[0053] The storage medium of the controller unit 120 and the data processing unit 130 may include, for example, a ROM, a floppy disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, or a nonvolatile memory card.

[0054] The controller unit 120 may be configured and / or arranged to be used in different ways. For example, in some implementations, a single controller unit 120 may be used; in other implementations, multiple controller units 120 are configured to work together (e.g., based on a distributed processing configuration) or individually, with each controller unit 120 configured to handle specific aspects and / or functions, and / or process data used to generate a model that is only used for a specific medical imaging system 100. In some implementations, the controller unit 120 may be local (e.g., co-located with one or more medical imaging systems 100, such as within the same facility and / or the same local network); in other implementations, the controller unit 120 may be remote and therefore only accessible via a remote connection (e.g., via the Internet or other available remote access technology). In a particular implementation, the controller unit 120 may be configured in a cloud-like manner and may be accessed and / or used in a manner substantially similar to the manner in which other cloud-based systems are accessed and used.

[0055] The MRI system 100 further includes a detection couch 140 for placing the detection object 116 thereon. The detection couch 140 can be moved into or out of the imaging space by moving the detection couch 140 based on a control signal from the controller unit 120.

[0056] The MRI system 100 further includes an operation console unit 150 connected to the controller unit 120. The operation console unit 150 can send the acquired operation signal to the controller unit 120 to control the working state of the above-mentioned components such as the detection bed 140 and the scanner 110. The operation signal may include, for example, a scanning protocol and parameters selected manually or automatically. The scanning protocol may include the above-mentioned imaging sequence. In addition, the operation console unit 150 can send the acquired operation signal to the controller unit 120 to control the data processing unit 130 to obtain a desired image.

[0057] The operation console unit 150 may include a user input device, such as a keyboard, a mouse, a voice-activated controller, or any other suitable input device, through which an operator may input operation signals / control signals to the controller unit 120 .

[0058] The MRI system 100 may further include a display unit 160 , which may be connected to the operation console unit 150 to display an operation interface, and may also be connected to the data processing unit 130 to display images.

[0059] In some embodiments, system 100 can be connected to one or more display units, cloud networks, printers, workstations, and / or similar devices located locally or remotely via one or more configurable wired and / or wireless networks, such as the Internet and / or a virtual private network.

[0060] Figure 2 FIG. 2 is a schematic diagram showing a positioning device 200 for an implant of a magnetic resonance imaging system according to some embodiments of the present invention. Figure 2 As shown, the positioning device 200 includes a control module 210 and a reconstruction module 220 .

[0061] The control module 210 is used to execute a first scanning sequence to acquire raw image data, wherein the first scanning sequence includes a radio frequency excitation pulse and a first layer selection gradient pulse corresponding to the radio frequency excitation pulse, and a radio frequency refocusing pulse and a second layer selection gradient pulse corresponding to the radio frequency refocusing pulse, wherein the frequency of the radio frequency excitation pulse has a preset offset compared to the center frequency, and the direction of the second layer selection gradient pulse is opposite to that of the first layer selection gradient pulse. In some embodiments, the control module 210 saves the acquired raw image data in the K space, and the raw image data is data corresponding to the frequency domain.

[0062] Specifically, the radio frequency excitation pulse is used to excite the edge tissue of the implant, and more specifically, the radio frequency excitation pulse containing a preset offset is used to excite the edge tissue of the implant to confirm the exact position of the implant. Usually, in a 1.5T magnetic field environment, the precession frequency of protons is about 64MHZ, that is, the center frequency of the radio frequency excitation pulse is 64MHZ, and the implant will make the main magnetic field in the magnetic resonance scanning process uneven, and when the main magnetic field is uneven, the precession frequency of the protons will also be offset accordingly and will no longer be 64MHZ. In order to accurately excite the tissue around the implant, the frequency of the radio frequency excitation pulse needs to have a preset frequency offset compared to the center frequency.

[0063] In some embodiments, the preset offset is determined based on the relevant parameters of the implant. Specifically, the relevant parameters of the implant include at least one of the material, size, and type of the implant. In some embodiments, the preset offset can be obtained based on a lookup table (LUT), which includes the relevant parameters of the implant and its corresponding preset offset relative to the center frequency. The frequency offset can be obtained based on a phantom during the experimental phase and stored in the magnetic resonance imaging system. In other embodiments, the preset offset can also be manually input by the operator.

[0064] Figure 3 FIG. 4 shows a schematic diagram of a first scanning pulse. Figure 3 As shown, "RF" shows the Figure 1 The RF pulse sequence emitted by the RF transmitting coil 112 in the magnetic resonance imaging system shown includes a 90° RF excitation pulse and a 180° RF refocusing pulse, "Gs" shows the pulse sequence of the slice selection gradient, "Gr" shows the pulse sequence of the phase gradient, and "Gp" shows the pulse sequence of the frequency (readout) gradient.

[0065] Generally, after transmitting a 90° RF excitation pulse, a first layer selection gradient pulse Gs is applied to the gradient coil to generate a layer selection gradient magnetic field. Next, a 180° RF refocusing pulse is transmitted a predetermined time after the 90° RF excitation pulse, at which time a second layer selection gradient pulse Gs is applied to the gradient coil to generate a layer selection gradient magnetic field, and after the 180° RF refocusing pulse, a frequency gradient pulse Gp alternating in positive and negative directions is applied to the gradient coil to generate a frequency (readout) gradient magnetic field, and a predetermined phase gradient pulse Gr is applied to the gradient coil to generate a phase gradient magnetic field.

[0066] Typically, for the layer selection gradient Gs, the direction of the second layer selection gradient pulse is the same as that of the first layer selection gradient pulse. In the positioning device of some embodiments of the present invention, by reversing the direction of the second layer selection gradient pulse corresponding to the 180° radio frequency refocusing pulse, each layer (slice) can be separated into a separate frequency bandwidth, and the frequency bandwidth corresponding to the current layer selection can be imaged separately, thereby reducing artifacts and distortion caused by the implant and more effectively acquiring the edge tissue image of the implant.

[0067] Those skilled in the art should understand that Figure 3 Only one example of various pulse sequences is shown. In an actual scanning process, there may be various pulse sequence forms based on different scanning protocols.

[0068] Figure 4 A comparison diagram of edge images of an implant obtained by scanning based on different first scanning pulses is shown, wherein: Figure 4 (1) is an edge image of the implant obtained when the direction of the second slice selection gradient pulse is the same as that of the first slice selection gradient pulse and the frequency of the radio frequency excitation pulse is the center frequency; Figure 4 (2) an edge image of the implant obtained when the direction of the second slice selection gradient pulse is opposite to that of the first slice selection gradient pulse and the frequency of the radio frequency excitation pulse is the center frequency; Figure 4 (3) An edge image of the implant obtained when the second slice selection gradient pulse is in the opposite direction to the first slice selection gradient pulse and the frequency of the RF excitation pulse has a 6 kHz offset compared to the center frequency; Figure 4 (4) is an edge image of the implant obtained when the direction of the second slice selection gradient pulse is opposite to that of the first slice selection gradient pulse and the frequency of the RF excitation pulse has a 10 kHz offset compared to the center frequency.

[0069] pass Figure 4 (1) and Figure 4 (2) By comparison, it can be seen that by reversing the direction of the second slice selection gradient pulse corresponding to the RF refocusing pulse, the artifacts and data loss caused by the implant can be effectively reduced. Figure 4 (2) and Figure 4 (3) By comparison, it can be seen that by setting a preset offset between the frequency of the RF excitation pulse and the center frequency, the marginal tissue of the implant can be effectively stimulated and an accurate marginal image of the implant can be obtained. Figure 4 (3) and Figure 4 (4) By comparison, it can be seen that for different implants, for example, implants of different types, different sizes or different materials, the corresponding preset offsets are different. Through experiments, the optimal preset offsets corresponding to implants with different parameters can be determined.

[0070] Please continue to refer to Figure 2The reconstruction module 220 is used to reconstruct the edge image of the implant based on the original image data. In some embodiments, the reconstruction module 220 reconstructs based on the original image data stored in the K space to obtain the edge image of the implant. Specifically, the edge image of the implant can be obtained by performing Fourier transform on the original image data stored in the K space.

[0071] In some embodiments, the RF receiving coil is configured as a single channel, that is, the RF receiving coil includes an RF receiving coil unit, the original image data includes the magnetic resonance signal received and transmitted by the single channel, and the reconstruction module 220 reconstructs based on the magnetic resonance signal to obtain an edge image.

[0072] In other embodiments, the RF receiving coil is configured as a multi-channel, that is, the RF receiving coil includes a plurality of RF receiving coil units, the multiple channels receive magnetic resonance signals respectively and store them in the K space, and the reconstruction module 220 reconstructs based on the magnetic resonance signals to obtain edge images. However, in the process of receiving magnetic resonance signals, each RF receiving coil unit has different sensitivities to different parts in the imaging space, for example, it is more sensitive to parts close to the RF receiving coil unit and less sensitive to parts far from the RF receiving coil unit. If reconstruction is performed directly based on the magnetic resonance signals received by the multiple channels, the phase information in the acquired edge image may be lost and the position information of the implant may be inaccurate.

[0073] In order to avoid the loss of phase information and obtain more accurate implant location information, the reconstruction module 220 is further used to reconstruct the original image data based on the coil sensitivity map, wherein the original image data includes data received by multiple RF receiving channels. Specifically, the coil sensitivity map includes a coil sensitivity map corresponding to each RF receiving coil unit, and the reconstruction module 220 can reconstruct the image data (or magnetic resonance signal) received by the RF receiving coil unit based on the coil sensitivity map corresponding to each RF receiving coil unit to obtain the edge image of the implant.

[0074] The term "coil sensitivity" describes the sensitivity of the RF receiving coil to the received magnetic resonance signal. The coil sensitivity map can be obtained during the test phase and stored in the magnetic resonance imaging system, such as before delivery, system installation, or maintenance service.

[0075] In some embodiments, before reconstructing the original image data based on the coil sensitivity map, the reconstruction module 220 further performs low-pass filtering on the data received by the multiple RF receiving channels to perform smoothing and denoising. In some embodiments, the low-pass filter includes filters such as SCIC filter, homomorphic filter and ITK-N4 bias field correction filter.

[0076] In some embodiments, the control module 210 in the positioning device 200 may be as follows: Figure 1 In the controller unit 120 or a part thereof in the magnetic resonance imaging system 100 shown, the reconstruction module 220 may be as follows: Figure 1 The data processing unit 130 or a part thereof in the magnetic resonance imaging system 100 shown. In other embodiments, the magnetic resonance imaging system 100 includes a processor (not shown in the figure), which is integrated in the controller unit 120 and is used to control the magnetic resonance imaging system to perform a first scanning sequence to obtain raw image data and reconstruct an edge image of the implant based on the raw image data, that is, the control module 210 and the reconstruction module 220 can be integrated together.

[0077] In some embodiments, the positioning device 200 further includes a judgment module 230. The judgment module 230 is used to judge whether the detected object contains an implant based on the difference between the one-dimensional signal or image obtained by the second scanning sequence and the third scanning sequence, wherein the frequency encoding directions of the second scanning sequence and the third scanning sequence are different.

[0078] The term "one-dimensional signal" refers to the time domain signal obtained by Fourier transforming a row or column of data in the K space, which can also be understood as the projection of the two-dimensional image amplitude signal in one direction. The term "image" refers to the two-dimensional image obtained by Fourier transforming the data in the entire K space.

[0079] Specifically, Figure 5 Shows Figure 2 The schematic diagram of the judgment module in the positioning device shown in FIG. Figure 5 As shown, the determination module 230 further includes a first unit 301 , a second unit 302 and a third unit 303 .

[0080] In some embodiments, the first unit 301 is used to execute a second scanning sequence 310 to acquire a first image or a first set of one-dimensional signals 317 of the detected object, and the second scanning sequence 310 includes a first frequency encoding direction 311 .

[0081] Specifically, first, the first unit 301 scans the object to be detected along the first frequency encoding direction 311 and different phase gradients, and stores the acquired first set of image data 313 in the K space.

[0082] Secondly, a row or a column of image data 315 corresponding to a specific frequency is selected in the K space. Specifically, the specific frequency is frequency 0, wherein the row or a column of image data 315 corresponding to frequency 0 is a row or a column in the K space that is perpendicular to the first frequency encoding direction 311.

[0083] Finally, the above-mentioned row or column of image data 315 is Fourier transformed 316 to obtain a first group of one-dimensional signals 317. Of course, the first group of image data 313 in the entire K space can also be Fourier transformed to obtain a first image (not shown in the figure).

[0084] The second unit 302 is used to execute a third scanning sequence 320 to obtain a second image or a second group of one-dimensional signals 327 of the detected object. The third scanning sequence 320 includes a second frequency encoding direction 321 , which is perpendicular to the first frequency encoding direction 311 .

[0085] In some embodiments, first, the second unit 302 is used to determine a specific phase, and the specific phase and the specific frequency correspond to the same row or column in the K space. Specifically, the specific phase and the specific frequency correspond to the same position in the K space.

[0086] Secondly, the second unit 302 is used to scan the detected object along the second frequency encoding direction 321 and the specific phase) to obtain image data of the same row or the same column as the second group of image data 325. Preferably, the specific phase is 0, which corresponds to the frequency of 0 in the second scanning sequence. In addition, in the second unit 302, since the phase gradient is not changed, the acquired second group of image data 325 only includes a row or a column in the K space that is the same as the second frequency encoding direction 321. Preferably, when the fixed phase gradient is 0, the row or column in the K space that is the same as the second frequency encoding direction 321 and located in the middle is filled.

[0087] Finally, Fourier transform is performed on the second set of image data 325 to obtain a second set of one-dimensional signals 327 .

[0088] In some other embodiments, the second unit 302 is used to scan the detected object along the second frequency encoding direction 321 and different phase gradients, and store the acquired image data 323 in the K space, and perform Fourier transform on the image data in the entire K space to obtain a second image (not shown in the figure). In some other embodiments, the second unit 302 is used to scan the detected object along the second frequency encoding direction 321 and different phase gradients, and store the acquired image data 323 in the K space, and then select a row or a column of data corresponding to the phase of 0 in the K space for Fourier transform to obtain a second set of one-dimensional signals.

[0089] When acquiring the second set of one-dimensional signals, a fixed phase gradient (for example, 0 phase) can be selected so that scanning only needs to be performed along the second frequency encoding direction 321, thereby reducing the scanning time for confirming whether the implanted device exists, reducing the specific absorption rate (SAR) value, and reducing the risk to the subject being detected.

[0090] The term "SAR" refers to the power or energy absorbed per unit of human body, with the unit of W / kg. SAR is a commonly used safety-related parameter during magnetic resonance imaging.

[0091] The third unit 303 is used to determine whether the detected object contains an implant based on the difference between the first image and the second image or the difference between the first group of one-dimensional signals and the second group of one-dimensional signals.

[0092] Specifically, after acquiring the first image and the second image, or the first group of one-dimensional signals 317 and the second group of one-dimensional signals 327, the third unit 303 can determine whether the detected object contains an implant according to the difference between the first image and the second image, or the difference between the first group of one-dimensional signals 317 and the second group of one-dimensional signals 327. In some embodiments, when the difference between the first image and the second image exceeds a preset threshold, it is determined that the detected object contains an implant. In some embodiments, when the difference between the first group of one-dimensional signals 317 and the second group of one-dimensional signals 327 exceeds a preset threshold, it is determined that the detected object contains an implant.

[0093] Figure 318 represents the trend of the signal amplitude of the first group of one-dimensional signals and the second group of one-dimensional signals changing over time. Curve 319 corresponds to the first group of one-dimensional signals 317, and curve 329 corresponds to the second group of one-dimensional signals. It can be seen that when there is an implant in the object being tested, the trend of the magnetic resonance signal in the amplitude 319 of the first group of one-dimensional signals and the amplitude 329 of the second group of one-dimensional signals changing over time is quite different, that is, when the implant exists, the difference between the first group of one-dimensional signals 317 and the second group of one-dimensional signals 327 is large. Therefore, by using the difference between the images obtained by two scanning sequences with different frequency encoding directions, it is very convenient to confirm whether there is an implant in the object being tested. Among them, the signal amplitude refers to the projection of the two-dimensional image signal amplitude on one dimension.

[0094] Although in some embodiments of the present invention, it is pointed out that whether the object being inspected contains an implant can be determined based on the difference between images acquired by two scanning sequences with different frequency encoding directions, those skilled in the art should understand that determining whether an implant device exists is not limited to the above-mentioned method, and the determination can be made in any other suitable manner. For example, two sets of images can be acquired by changing imaging parameters (for example, echo time TE), and the difference image can be calculated to determine whether an implant device exists.

[0095] Please continue to refer to Figure 2 The positioning device 200 further includes an indication module 240, which is used to indicate the predicted values ​​of the magnetic resonance imaging system parameters related to the implant and the safety status of one or more of the parameters after completing the imaging scan.

[0096] Specifically, during the imaging scan, after the first scanning sequence is executed to determine the position information of the implant, the indication module 240 can predict and indicate the value and safety status of the magnetic resonance imaging system parameters related to the implant according to the parameters and position information of the implant, and provide reference or suggestions for the subsequent formal scan. The parameters of the implant include the size, material or type of the implant, and the magnetic resonance imaging system parameters related to the implant include one or more of the gradient magnetic field strength, the radio frequency magnetic field strength, the main magnetic field spatial gradient strength, the temperature, and the absorption rate.

[0097] The safety status of one or more of the parameters can be different types (e.g., colors, text, graphics, or sounds) to represent different safety statuses (e.g., safe, relatively dangerous, dangerous, etc., or high risk, medium risk, low risk, etc.). In some embodiments, when the value of the parameter exceeds its preset threshold, a corresponding warning is issued. Further, when the value of the parameter exceeds its preset threshold, a warning is issued by changing the safety status of the parameter. For example, but not limited to, when the value of the radio frequency field strength in the parameter exceeds the preset threshold, the safety status of the radio frequency field strength is changed from green to orange, or from orange to red to issue a warning. Those skilled in the art should understand that the change of the safety status of the parameter is not limited to the above-mentioned method.

[0098] Figure 6 A schematic diagram showing a user interface for scanning risk indications according to some embodiments of the present invention, Figure 7 Schematic diagrams showing user interfaces for scanning risk indications according to other embodiments of the present invention. Figure 6-7 As shown, for implants with the same parameters and in the same position, Figure 6 and 7 The predicted scanning risks corresponding to the formal scanning parts of the head and abdomen are shown respectively, wherein: Figure 6The scan risk user interface corresponding to the head scan, Figure 7 The present invention is a scanning risk user interface corresponding to the abdomen. The parameters related to the MRI system related to the implant in the scanning risk include the gradient magnetic field strength (dB / dt), the absorption rate (SAR) and the main magnetic field spatial gradient strength (B0+). A warning is issued by changing the color of the safety status to remind the user or operator that a certain parameter has a high risk or a medium risk.

[0099] pass Figure 6 and Figure 7 By comparison, it can be found that for the same implant parameters and position, the risks to the subject are different due to different formal scanning locations. For example, for a subject with a pacemaker, the risk of scanning the abdomen is higher, especially when the SAR value and spatial gradient value are very high. During the formal scanning process, the user or operator can change certain scanning parameters to avoid causing harm to the subject.

[0100] although Figure 6-7 The user interface of the scanning risk indication is shown. However, those skilled in the art should understand that the user interface is not limited to the above-mentioned bar graph display method, as long as the status of the real-time parameters can be displayed, for example, each parameter can be represented by a pointer. In addition, although the figure shows that when a certain parameter exceeds the threshold, a warning is issued by changing the color, it is not limited to this method. It can also be a sound to warn, or a combination of changing the state and issuing a sound. Furthermore, the user interface is not limited to only displaying Figure 6-7 The content may also include any other related information or functions.

[0101] Figure 8 FIG. 4 is a flow chart showing a method 400 for positioning an implant in a magnetic resonance imaging system according to some embodiments of the present invention. Figure 8 As shown, the implant positioning method 400 includes step 410 and step 420 .

[0102] In step 410, a first scanning sequence is executed to acquire raw image data, wherein the first scanning sequence includes a radio frequency excitation pulse and a first layer selection gradient pulse corresponding to the radio frequency excitation pulse, and a radio frequency refocusing pulse and a second layer selection gradient pulse corresponding to the radio frequency refocusing pulse, wherein the frequency of the radio frequency excitation pulse has a preset offset compared to the center frequency, and the direction of the second layer selection gradient pulse is opposite to that of the first layer selection gradient pulse.

[0103] Specifically, the radio frequency excitation pulse is used to excite the edge tissue of the implant. More specifically, the radio frequency excitation pulse including a preset offset is used to excite the edge tissue of the implant.

[0104] Specifically, the preset offset is determined based on the relevant parameters of the implant. Specifically, the relevant parameters of the implant include at least one of the material, size, and type of the implant. In some embodiments, the preset offset can be obtained based on a lookup table (LUT), which includes the relevant parameters of the implant and its corresponding preset offset compared to the center frequency. The frequency offset can be obtained based on a phantom during the experimental stage and stored in the magnetic resonance imaging system.

[0105] Specifically, reconstructing the edge image of the implant includes reconstructing original image data based on the coil sensitivity map, wherein the original image data includes data received by multiple radio frequency receiving channels.

[0106] In step 420, a marginal image of the implant is reconstructed based on the original image data.

[0107] Specifically, when the RF receiving coil is a single channel, reconstruction can be performed based on the data received and transmitted by the single channel to obtain an edge image of the implant. When the RF receiving coil is a multi-channel, the original image data can be reconstructed based on the coil sensitivity map, wherein the original image data includes data received by multiple RF receiving channels. In some embodiments, before the original image data is reconstructed based on the coil sensitivity map, the data received by multiple RF receiving channels are further low-pass filtered to perform smoothing and denoising.

[0108] In some embodiments, the implant positioning method 400 further includes step 430 .

[0109] In step 430, based on the difference between the one-dimensional signal or image obtained by the second scanning sequence and the third scanning sequence with different frequency encoding directions, it is determined whether the object under test contains an implant. The specific method for determining whether the object under test contains an implant will be described later in conjunction with Fig. 9 describe.

[0110] In some embodiments, implant positioning method 400 includes step 440 .

[0111] In step 440, during the performance of the imaging scan, after the imaging scan is completed, predicted values ​​of magnetic resonance imaging system parameters associated with the implant and safe states of one or more of the parameters are indicated.

[0112] Specifically, the magnetic resonance imaging system parameters related to the implant include one or more of the gradient magnetic field strength, the radio frequency magnetic field strength, the main magnetic field spatial gradient strength, the temperature and the absorptivity. By changing the indication state corresponding to the parameter (for example, color, text, graphics or sound), the safety state of the parameter (for example, safe, relatively dangerous, dangerous, etc.) can be indicated in real time to remind the operator to adjust or select a relatively safe parameter configuration or scanning sequence during the formal scanning process.

[0113] Fig. 9 Shows Figure 8 Flow chart of determining whether the detected object contains an implant 500 in some embodiments of the positioning method. Fig. 9 As shown, determining whether the detected object contains an implant 500 includes step 510, step 520 and step 530.

[0114] In step 510, the second scanning sequence is executed to acquire a first group of one-dimensional signals of the detected object, and the second scanning sequence includes a first frequency encoding direction.

[0115] Specifically, step 510 includes step 511 , step 512 and step 513 .

[0116] In step 511, the detected object is scanned along the first frequency encoding direction, and the acquired first set of image data is stored in the K space. Specifically, the second scanning sequence includes scanning with different phase encoding gradients, and the magnetic resonance signals corresponding to the same frequency encoding but different phase encoding are filled into a row or a column in the K space perpendicular to the first frequency encoding direction, and in the K space, the phase encoding corresponding to the center position is 0, and the signal strength is the largest, while the phase gradient corresponding to the peripheral position is the largest, and the spatial information is the richest.

[0117] In step 512, a row or a column of image data corresponding to a specific frequency is selected in the K space. Specifically, the specific frequency may be a frequency of 0, and in the first frequency encoding direction, the frequency of data corresponding to a row or a column in the K space that is perpendicular to the first frequency encoding direction and at the center of the K space is 0.

[0118] In step 513, Fourier transform is performed on the above-mentioned row or column of image data to obtain a first set of one-dimensional signals. Specifically, the first set of one-dimensional signals can be obtained by performing Fourier transform or inverse Fourier transform on a row or column of image data with a frequency of 0 in K space.

[0119] In step 520, the third scanning sequence is executed to acquire a second set of one-dimensional signals of the detected object, and the third scanning sequence includes a second frequency encoding direction, which is perpendicular to the first frequency encoding direction.

[0120] In some embodiments, step 520 includes step 521 , step 522 , and step 523 .

[0121] In step 521 , a specific phase is determined, where the specific phase and the specific frequency correspond to the same row or the same column in the K space.

[0122] In step 522, the object to be detected is scanned along the second frequency encoding direction and the specific phase to obtain image data of the same row or column as the second set of image data. Specifically, in the third scanning direction, the object to be detected is scanned along the second frequency encoding direction using a fixed phase gradient, and the data or magnetic resonance signal can be filled into a row or column in the K space that is the same as the second frequency encoding direction. Preferably, the fixed phase is 0, and the signal strength is the strongest at this time, and the collected data is filled into a row or column in the center of the K space. In the third scanning sequence, only a fixed phase gradient is needed to encode along the frequency direction, the scanning time is shorter, the SAR value is lower, and it is safer for the object to be detected.

[0123] In step 523, Fourier transform is performed on the second set of image data to obtain a second set of one-dimensional signals.

[0124] In step 530, based on the difference between the first set of one-dimensional signals and the second set of one-dimensional signals, it is determined whether the detected object contains an implant.

[0125] Specifically, when the difference between the first group of one-dimensional signals and the second group of one-dimensional signals exceeds a preset threshold, it is determined that the detection object contains an implant.

[0126] Fig.10 Shows Figure 8 Flowchart of determining whether the detected object contains an implant 600 in some other embodiments of the positioning method. Fig.10 As shown, the method 600 for determining whether the detected object contains an implant is different from the method 500 for determining whether the detected object contains an implant in that step 610 is used to execute a second scanning sequence to obtain a first image of the detected object, step 620 is used to execute a third scanning sequence to obtain a second image of the detected object, and step 630 is used to determine whether the detected object contains an implant based on the difference between the first image and the second image.

[0127] Specifically, step 610 includes step 611 and step 612 .

[0128] In step 611, the object to be detected is scanned along a first frequency encoding direction, and the acquired first set of image data is stored in K space.

[0129] In step 612, Fourier transform is performed on the first set of image data to obtain a first image.

[0130] Specifically, step 620 includes step 621 and step 622 .

[0131] In step 621, the object to be detected is scanned along the second frequency encoding direction, and the acquired second set of image data is stored in the K space. Specifically, in the third scanning direction, the phase gradient also changes.

[0132] In step 622, Fourier transform is performed on the second set of image data to obtain a second image.

[0133] Fig.11 shows the image display interface of some embodiments of the present invention, such as Fig.11 As shown, the display unit of the magnetic resonance imaging system includes an image display interface 700, which includes a first option 710 related to the detection of implant position confirmation and a second option 720 related to the detection of whether the implant exists. In the first option 710, it includes a first scanning sequence, and the magnetic resonance imaging system can perform steps 410 and 420 to obtain an edge image of the implant to obtain the accurate position of the implant. In the second option 720, it includes a second scanning sequence and a third scanning sequence, and the magnetic resonance imaging system can perform steps 510, 520 and 530 to determine whether the implant exists in the detected object through the difference between the two images or one-dimensional signals obtained by the second scanning sequence and the third scanning sequence.

[0134] The above-mentioned “detection of the presence of an implant” and “detection of confirmation of the implant position” are for illustration only, and those skilled in the art may set any option name that is convenient for the operator to confirm.

[0135] In summary, the implant positioning method of the magnetic resonance imaging system of some embodiments of the present invention can effectively excite the edge tissue of the implant by setting a preset offset between the frequency of the radio frequency excitation pulse and the center frequency, so as to confirm the accurate position of the implant; by reversing the direction of the second layer selection gradient pulse corresponding to the radio frequency refocusing pulse, metal artifacts and distortion can be reduced, thereby more effectively obtaining the edge tissue image of the implant; by reconstructing the original image data based on the coil sensitivity map, the loss of phase information in the process of reconstructing the magnetic resonance signals of multiple radio frequency receiving channels can be avoided, and more accurate implant position information can be obtained; in the process of confirming whether there is an implant in the detected object, by comparing the images or one-dimensional signals obtained by two scans, it can be very convenient to confirm whether there is an implant in the detected object, and in the subsequent scan (corresponding to the third scanning sequence), there is no need to change the phase encoding gradient, only need to scan along the frequency encoding direction, and only obtain one row or one column of data in the K space, which can reduce the scanning time, reduce the SAR value, and reduce the degree of danger to the detected object.

[0136] The present invention may also provide a non-transitory computer-readable storage medium for storing an instruction set and / or a computer program. When the instruction set and / or the computer program are executed by a computer, the computer executes the above-mentioned method for obtaining a predicted image of a truncated portion. The computer that executes the instruction set and / or the computer program may be a computer of an MRI system or other device / module of the MRI system. In one embodiment, the instruction set and / or the computer program may be compiled in a processor / controller of the computer.

[0137] Specifically, the set of instructions and / or computer program, when executed by a computer, causes the computer to:

[0138] A first scanning sequence is executed to acquire raw image data, wherein the first scanning sequence includes: a radio frequency excitation pulse, and a first layer selection gradient pulse corresponding to the radio frequency excitation pulse, and the frequency of the radio frequency excitation pulse has a preset offset compared to the center frequency; and a radio frequency refocusing pulse, and a second layer selection gradient pulse corresponding to the radio frequency refocusing pulse, and the direction of the second layer selection gradient pulse is opposite to the direction of the first layer selection gradient pulse.

[0139] Based on the raw image data, a marginal image of the implant is reconstructed.

[0140] The instructions described above may be combined into one instruction for execution, and any instruction may be split into multiple instructions for execution. In addition, the execution order of the instructions described above is not limited to the above order.

[0141] As used herein, the term "computer" may include any processor-based or microprocessor-based system, including systems using microcontrollers, reduced instruction set computers (RISC), application specific integrated circuits (ASICs), logic circuits, and any other circuits or processors capable of performing the functions described herein. The above examples are exemplary only, and are thus not intended to limit the definition and / or meaning of the term "computer" in any way.

[0142] The instruction set may include various commands that instruct a computer or processor as a processing machine to perform specific operations, such as the methods and processes of various embodiments. The instruction set may take the form of a software program that may form part of one or more tangible non-transitory computer-readable media. The software may take various forms such as system software or application software. In addition, the software may take the form of a collection of independent programs or modules, a program module within a larger program, or a portion of a program module. The software may also include modular programming in the form of object-oriented programming. The processing of input data by the processing machine may be in response to operator commands, or in response to previous processing results, or in response to a request made by another processing machine.

[0143] Some exemplary embodiments have been described above, however, it should be understood that various modifications may be made. For example, if the described techniques are performed in a different order and / or if the components in the described systems, architectures, devices, or circuits are combined in different ways and / or replaced or supplemented by other components or their equivalents, suitable results may be achieved. Accordingly, other implementations also fall within the scope of protection of the claims.

Claims

1. A method for positioning an implant of a magnetic resonance imaging system, comprising: Based on the difference between the one-dimensional signal or image acquired by the second scanning sequence and the third scanning sequence, it is determined whether the detected object contains an implant, wherein the frequency encoding directions of the second scanning sequence and the third scanning sequence are different; wherein determining whether the detected object contains an implant comprises: Executing the second scanning sequence to acquire a first image or a first set of one-dimensional signals of the detected object, wherein the second scanning sequence includes a first frequency encoding direction; Execute the third scanning sequence to obtain a second image or a second group of one-dimensional signals of the object to be detected, and the third scanning sequence includes a second frequency encoding direction, and the second frequency encoding direction is perpendicular to the first frequency encoding direction; and based on the difference between the first image and the second image or the difference between the first group of one-dimensional signals and the second group of one-dimensional signals, determine whether the object to be detected contains an implant.

2. The positioning method according to claim 1, wherein: The method further comprises: executing a first scanning sequence to obtain raw image data; and reconstructing an edge image of the implant based on the raw image data; wherein the first scanning sequence comprises: a radio frequency excitation pulse, and a first slice selection gradient pulse corresponding to the radio frequency excitation pulse, and the frequency of the radio frequency excitation pulse has a preset offset compared to the center frequency; and A radio frequency refocusing pulse, and a second slice selection gradient pulse corresponding to the radio frequency refocusing pulse, wherein the direction of the second slice selection gradient pulse is opposite to the direction of the first slice selection gradient pulse.

3. The positioning method according to claim 2, wherein: The radio frequency excitation pulses are used to excite tissues at the edges of the implant.

4. The positioning method according to claim 2, wherein: The preset offset is determined based on relevant parameters of the implant.

5. The positioning method according to claim 2, wherein: Reconstructing the edge image of the implant includes: reconstructing the original image data based on the coil sensitivity map, wherein the original image data includes data received by multiple radio frequency receiving channels.

6. The positioning method according to claim 1, wherein: Acquiring a first set of one-dimensional signals of the detected object includes: Scanning the detected object along the first frequency encoding direction, and storing the acquired first set of image data in K space; Selecting a row or a column of image data corresponding to a specific frequency in the K space; and Perform Fourier transform on the row or column of image data to obtain the first group of one-dimensional signals.

7. The positioning method according to claim 6, wherein: Acquiring a second set of one-dimensional signals of the detected object includes: Determine a specific phase, where the specific phase and the specific frequency correspond to the same row or the same column in the K space; Scanning the detected object along the second frequency encoding direction and the specific phase to obtain image data of the same row or the same column as the second group of image data; and Perform Fourier transform on the second image data to obtain the second group of one-dimensional signals.

8. The positioning method according to claim 1, wherein: Based on the difference between the first image and the second image or the difference between the first group of one-dimensional signals and the second group of one-dimensional signals, determining whether the detected object contains an implant comprises: When the difference between the first image and the second image exceeds a preset threshold, or the difference between the first group of one-dimensional signals and the second group of one-dimensional signals exceeds a preset threshold, it is determined that the detection object contains an implant.

9. The positioning method according to claim 2, wherein: Further comprising: indicating predicted values ​​of magnetic resonance imaging system parameters associated with the implant, and safe states of one or more of the parameters, after completing the imaging scan.

10. A non-transitory computer-readable storage medium for storing a computer program, wherein when the computer program is executed by a computer, the computer executes the implant positioning method according to any one of claims 1 to 9.

11. A display method comprising a second option related to the detection of the presence or absence of an implant, the second option being used to: Executing a second scanning sequence to acquire a first image or a first set of one-dimensional signals of the detected object, wherein the second scanning sequence includes a first frequency encoding direction; Execute a third scanning sequence to acquire a second image or a second set of one-dimensional signals of the detected object, wherein the third scanning sequence includes a second frequency encoding direction, and the second frequency encoding direction is perpendicular to the first frequency encoding direction; and determine whether the detected object contains an implant based on a difference between the first image and the second image or a difference between the first set of one-dimensional signals and the second set of one-dimensional signals.

12. The display method according to claim 11, wherein: Also included is a first option related to detection of implant position confirmation, the first option being used to: executing a first scanning sequence to acquire raw image data; as well as reconstructing an edge image of the implant based on the original image data; Wherein, the first scanning sequence includes: A radio frequency excitation pulse, and a first slice selection gradient pulse corresponding to the radio frequency excitation pulse, wherein the frequency of the radio frequency excitation pulse has a preset offset compared to the center frequency; and A radio frequency refocusing pulse, and a second slice selection gradient pulse corresponding to the radio frequency refocusing pulse, wherein the direction of the second slice selection gradient pulse is opposite to the direction of the first slice selection gradient pulse.

13. A magnetic resonance imaging system, comprising a positioning device for an implant, the positioning device comprising: A judgment module, which is used to judge whether the detected object contains an implant based on the difference between the one-dimensional signal or image obtained by the second scanning sequence and the third scanning sequence, wherein the frequency encoding directions of the second scanning sequence and the third scanning sequence are different; wherein the judgment module comprises: A first unit, configured to execute the second scanning sequence to acquire a first image or a first set of one-dimensional signals of the detected object, wherein the second scanning sequence includes a first frequency encoding direction; a second unit, configured to execute the third scanning sequence to acquire a second image or a second set of one-dimensional signals of the detected object, wherein the third scanning sequence includes a second frequency encoding direction, and the second frequency encoding direction is perpendicular to the first frequency encoding direction; and The third unit is used to determine whether the detected object contains an implant based on the difference between the first image and the second image or the difference between the first group of one-dimensional signals and the second group of one-dimensional signals.

14. The magnetic resonance imaging system of claim 13, wherein: Further including: A control module is configured to execute a first scanning sequence to obtain raw image data, wherein the first scanning sequence includes: A radio frequency excitation pulse, and a first slice selection gradient pulse corresponding to the radio frequency excitation pulse, wherein the frequency of the radio frequency excitation pulse has a preset offset compared to the center frequency; and a radio frequency refocusing pulse, and a second slice selection gradient pulse corresponding to the radio frequency refocusing pulse, wherein the direction of the second slice selection gradient pulse is opposite to the direction of the first slice selection gradient pulse; and A reconstruction module is used to reconstruct the edge image of the implant based on the original image data.

15. The magnetic resonance imaging system of claim 14, wherein: The radio frequency excitation pulses are used to excite tissues at the edges of the implant.

16. The magnetic resonance imaging system of claim 14, wherein: The preset offset is determined based on relevant parameters of the implant.

17. The magnetic resonance imaging system of claim 14, wherein: The reconstruction module is further used to reconstruct the original image data based on the coil sensitivity map, wherein the original image data includes data received by multiple radio frequency receiving channels.

18. The magnetic resonance imaging system of claim 14, wherein: Further included is an indication module for indicating predicted values ​​of magnetic resonance imaging system parameters associated with the implant and a safety status of one or more of the parameters after completing the imaging scan.

Images