Method for positioning a magnetic resonance imaging system and magnetic resonance imaging system

Abstract

The application provides a positioning method of a magnetic resonance imaging system, the magnetic resonance imaging system, and a non-transitory computer readable storage medium. The positioning method of the magnetic resonance imaging system comprises: obtaining a scatter parameter curve of a body coil in a process in which a detection bed carrying a detected object enters a scanning cavity of the magnetic resonance imaging system, obtaining a position of a to-be-detected part of the detected object based on the scatter parameter curve, and moving the detection bed based on the position of the to-be-detected part so that the to-be-detected part is located at the center of the scanning cavity.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of medical imaging, in particular to a positioning method of a magnetic resonance imaging system, a magnetic resonance imaging system, and a non-transitory computer readable storage medium. BACKGROUND

[0002] As a medical imaging modality, magnetic resonance imaging (MRI) can obtain images of human body without using X-ray or other ionizing radiation. MRI utilizes a magnet with a strong magnetic field to generate a main magnetic field B0. When a part of human body to be imaged is positioned in the main magnetic field B0, the nuclear spins associated with hydrogen nuclei in the tissues of the part of human body to be imaged are polarized, so that the tissues of the part of human body to be imaged produce a longitudinal magnetization vector in a macroscopic manner. After a radio frequency field B1 intersecting the direction of the main magnetic field B0 is applied, the direction of the protons rotating changes, so that the tissues of the part of human body to be imaged produce a transverse magnetization vector in a macroscopic manner. After the radio frequency field B1 is removed, the transverse magnetization vector decays in a spiral manner until it returns to zero, and a free induction decay signal is generated in the process of decay, which can be collected as a magnetic resonance signal, and an image of the tissues of the part of human body to be imaged can be reconstructed based on the collected signal. A gradient system is used to emit a slice selection gradient pulse, a phase encoding gradient pulse and a frequency encoding gradient pulse (also referred to as a readout gradient pulse) to provide three-dimensional position information to the above-mentioned magnetic resonance signal to realize image reconstruction.

[0003] Before a magnetic resonance imaging scan, the part of human body to be detected needs to be moved to the center of the scan cavity of the magnetic resonance imaging system by a detection bed for scanning and imaging, and there are different solutions for determining the specific position of the part of human body to be detected.

[0004] Generally, an operator or a doctor can use a manual positioning method, that is, during the process of the detection bed entering the scan cavity, a laser device located at the center of the scan cavity projects a mark, for example, a cross mark, on the body of the detected object, and the operator can determine the current position as the part to be detected based on the projected mark, that is, the scanning positioning is completed. However, this positioning method needs the user to perform related operations in the scan room, and the operation process is complex, and the laser device has a safety hazard to the detected object.

[0005] In addition, automatic positioning can also be performed based on a camera. Specifically, before scanning, an image of the detected object is acquired based on a camera installed in the scan room, the position of the part to be detected of the detected object is acquired based on image processing, and the detection bed is moved so that the part to be detected of the detected object is located at the center of the scan cavity. However, this positioning method is expensive and complex to implement. SUMMARY

[0006] The application provides a positioning method of a magnetic resonance imaging system, the magnetic resonance imaging system, and a non-transitory computer readable storage medium.

[0007] The exemplary embodiment of the application provides a positioning method of a magnetic resonance imaging system, the positioning method comprising: obtaining a scatter parameter curve of a body coil during a process in which a detection bed carrying a detected object enters a scanning cavity of the magnetic resonance imaging system; obtaining a position of a to-be-detected part of the detected object based on the scatter parameter curve; and moving the detection bed based on the position of the to-be-detected part so that the to-be-detected part is located at the center of the scanning cavity.

[0008] Specifically, obtaining the scatter parameter curve of the body coil comprises: obtaining the scatter parameters when the detected object is located at different positions of the scanning cavity, and generating the scatter parameter curve based on the scatter parameters obtained when the detected object is located at the different positions.

[0009] Specifically, obtaining the scatter parameters when the detected object is located at the different positions comprises: obtaining the scatter parameters of the body coil based on the reflected power and the output power of the body coil when the detected object is located at the different positions.

[0010] Specifically, obtaining the scatter parameters when the detected object is located at the different positions further comprises: applying a preset input power to the body coil, monitoring the output power and the reflected power of the body coil when the detected object is located at the different positions, and obtaining the scatter parameters corresponding to the different positions based on the ratio of the reflected power to the output power.

[0011] Specifically, obtaining the position of the to-be-detected part of the detected object comprises: determining the position of a local coil or a surface coil based on the position of a wave peak or a wave trough in the scatter parameter curve, and the position of the local coil or the surface coil is the position of the to-be-detected part.

[0012] Specifically, obtaining the position of the to-be-detected part of the detected object comprises: obtaining the distance between the head or the foot of the detected object and the lower abdomen based on the position of a wave trough in the scatter parameter curve, and estimating the distance between the head or the foot and the to-be-detected part based on the distance between the head or the foot and the lower abdomen to obtain the position of the to-be-detected part.

[0013] The exemplary embodiment of the application further provides a non-transitory computer readable storage medium for storing a computer program, the computer program being executed by a computer to make the computer execute the instructions of the positioning method for the magnetic resonance imaging system described above.

[0014] The exemplary embodiment of the present application also provides a magnetic resonance imaging system, which comprises a main magnet, a body coil for transmitting or receiving radio frequency signals, a detection bed for carrying and moving a to-be-detected object, and a positioning device, wherein the main magnet defines a scanning cavity inside, and the positioning device comprises a parameter scanning module, a part determining module and a control module, the parameter scanning module is used to obtain a scattering parameter curve of the body coil in the process that the detection bed carrying the to-be-detected object enters the scanning cavity of the magnetic resonance imaging system, the part determining module is used to obtain the position of a to-be-detected part of the to-be-detected object based on the scattering parameter curve, and the control module is used to move the detection bed based on the position of the to-be-detected part so that the to-be-detected part is located at the center of the scanning cavity.

[0015] Specifically, the scattering parameter curve is generated based on scattering parameters obtained when the to-be-detected object is located at different positions of the scanning cavity.

[0016] Specifically, the scattering parameter is obtained based on the reflected power and the output power of the body coil when the to-be-detected object is located at different positions of the scanning cavity.

[0017] Specifically, the parameter obtaining module is further used to apply a preset input power to the body coil, monitor the output power and the reflected power of the body coil when the to-be-detected object is located at the different positions, and obtain the scattering parameter corresponding to the different positions based on the ratio of the reflected power to the output power.

[0018] Specifically, the part determining module is further used to determine the position of the local coil or the surface coil based on the position of a wave peak or a wave trough in the scattering parameter curve, and the position of the local coil or the surface coil is the position of the to-be-detected part.

[0019] Specifically, the part determining module is further used to obtain the distance between the head or the foot of the to-be-detected object and the lower abdomen based on the position of a wave trough in the scattering parameter curve, and calculate the distance between the head or the foot and the to-be-detected part based on the distance between the head or the foot and the lower abdomen to obtain the position of the to-be-detected part.

[0020] Other features and aspects will become apparent from the following detailed description, the drawings, and the claims. BRIEF DESCRIPTION OF DRAWINGS

[0021] The present application can be better understood by describing the exemplary embodiments thereof with reference to the accompanying drawings, in which:

[0022] Figure 1 is a schematic diagram of a magnetic resonance imaging system according to some embodiments of the present application;

[0023] Figure 2 This is a schematic diagram of a positioning device for a magnetic resonance imaging system according to some embodiments of the present invention;

[0024] Figure 3 It is a schematic diagram of the scattering parameter values ​​corresponding to multiple parts of multiple objects being detected;

[0025] Figure 4 This is a schematic diagram of the scattering parameter curves of the object being tested in the absence of surface coils and local coils;

[0026] Figure 5 This is a schematic diagram of the scattering parameter curves of the object being detected in the presence of local coils;

[0027] Figure 6 This is a schematic diagram of the scattering parameter curves of the object being tested in the presence of surface coils;

[0028] Figure 7 This is a flowchart of a localization method for a magnetic resonance imaging system according to some embodiments of the present invention; and

[0029] Figure 8 yes Figure 7 The flowchart shown is a detailed process for obtaining the scattering parameter curve of the body coil in the positioning method. Detailed Implementation

[0030] The following describes specific embodiments of the present invention. It should be noted that, in order to provide a concise description, this specification cannot exhaustively describe all features of the actual embodiments. It should be understood that, in the actual implementation of any embodiment, just as in any engineering or design project, various specific decisions are often made to achieve the developer's specific goals and to meet system-related or business-related constraints, and this can change from one embodiment to another. Furthermore, it is understood that although the efforts made in this development process may be complex and lengthy, for those skilled in the art related to the content disclosed in this invention, some design, manufacturing, or production modifications based on the technical content disclosed herein are merely conventional technical means and should not be construed as insufficient content of this disclosure.

[0031] Unless otherwise defined, the technical or scientific terms used in the claims and description shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in the patent application description and claims of this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. The terms "an" or "a" and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms "comprising" or "including" and similar terms mean that the element or object preceding "comprising" or "including" encompasses the element or object listed following "comprising" or "including" and its equivalents, and do not exclude other elements or objects. The terms "connected" or "linked" and similar terms are not limited to physical or mechanical connections, nor are they limited to direct or indirect connections.

[0032] Figure 1 A schematic 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 MRI system 100 described above is only an example; in other embodiments, the MRI system 100 can have various variations, as long as it can acquire image data from the object being examined.

[0033] The scanner 110 can be used to acquire data of the object 116 being inspected. The controller unit 120 is coupled to the scanner 110 to control the operation of the scanner 110. The scanner 110 may include a main magnet 111, an RF transmitting coil 112, an RF transmitting link (not shown), a gradient coil system 117, a gradient coil driver 118, and an RF receiving coil 119.

[0034] The main magnet 111 typically includes, for example, a toroidal superconducting magnet mounted within a toroidal vacuum container. This toroidal superconducting magnet defines a cylindrical space surrounding the object under examination 116, i.e., a scanning chamber. The main magnet 111 can generate a constant main magnetic field, such as a main magnetic field B0, along the Z-direction of the cylindrical space. The MRI system 100 utilizes the generated main magnetic field B0 to transmit a magnetostatic pulse signal to the object under examination 116 placed in the imaging space, thereby ordering the precession of protons within the object under examination 116 and generating a longitudinal magnetization vector.

[0035] The radio frequency transmission link includes a frequency synthesizer 101, a radio frequency amplifier 103, and a transmit / receive (T / R) switch 105.

[0036] Frequency synthesizer 101 generates radio frequency (RF) pulses, which may include RF excitation pulses. These RF excitation pulses are amplified by RF amplifier 103 and applied to RF transmitting coil 112 via T / R switch 105. This causes RF transmitting coil 112 to emit an RF magnetic field B1 orthogonal to the main magnetic field B0 towards the object under test 116, exciting the atomic nuclei within the object under test 116 and transforming the longitudinal magnetization vector into a transverse magnetization vector. As the RF excitation pulse ends, the transverse magnetization vector of the object under test 116 gradually returns to zero, generating a free-induction decay signal, which is the magnetic resonance signal that can be acquired.

[0037] The radio frequency transmitting coil 112 can be a body coil, which can be connected to a T / R switch 105. By controlling the T / R switch, the body coil can be switched between transmitting and receiving modes. In the receiving mode, the body coil can be used to receive magnetic resonance signals from the object under test 116. Alternatively, the radio frequency transmitting coil 112 can also be a local coil, such as a head coil.

[0038] In some embodiments, the radio frequency transmitting coil is not limited to the body coil and local coil mentioned in this application, but may include other suitable coil types. Similarly, the radio frequency receiving coil is not limited to the body coil, local coil and surface coil mentioned in this application, but may include other suitable coil types.

[0039] The gradient coil system 117 generates a magnetic field gradient in the imaging space to provide three-dimensional position information for the aforementioned magnetic resonance signal. This magnetic resonance signal can be received by the radio frequency receiving coil 119 or by a body coil or local coil in receiving mode. The data processing unit 130 can process the received magnetic resonance signal to obtain the desired image or image data.

[0040] Specifically, the gradient coil system 117 may include three gradient coils, each of which generates a gradient magnetic field tilted to one of three mutually perpendicular spatial axes (e.g., the X-axis, Y-axis, and Z-axis), and generates gradient fields in each of the slice selection direction, phase encoding direction, and frequency encoding direction according to the imaging conditions. More specifically, the gradient coil system 117 applies a gradient field in the slice selection direction of the object under test 116 to select a slice; and the radio frequency transmission coil 112 transmits a radio frequency excitation pulse to the selected slice of the object under test 116 and excites the slice. The gradient coil system 117 also applies a gradient field in the phase encoding direction of the object under test 116 to perform phase encoding of 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 object under test 116 to perform frequency encoding of the magnetic resonance signal of the excited slice.

[0041] The gradient coil driver 118 is used to provide appropriate power signals to the three gradient coils respectively in response to the sequence control signals issued by the controller unit 120.

[0042] 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 volume coil. The data acquisition unit 114 may include, for example, a radio frequency preamplifier (not shown), a phase detector (not shown), and an analog-to-digital converter (not shown). The radio frequency preamplifier amplifies the magnetic resonance signals received by the radio frequency surface coil 119 or the volume coil, the phase detector performs phase detection on the amplified magnetic resonance signals, and the analog-to-digital converter converts the phase-detected magnetic resonance signals from analog signals to digital signals. The digitized magnetic resonance signals can be processed by the data processing unit 130 through calculations, reconstruction, etc., to obtain medical images.

[0043] The data processing unit 130 may include a computer and a storage medium on which a predetermined data processing program 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 control signals received from the controller unit 120. The data processing unit 130 may also be connected to the data acquisition unit 114 to receive magnetic resonance signals output by the data acquisition unit 114 in order to perform the aforementioned data processing.

[0044] The controller unit 120 may include a computer and a storage medium for storing programs executable by the computer. When the computer executes the program, it can cause multiple components of the scanner 110 to perform operations corresponding to an imaging sequence. The data processing unit 130 can also perform predetermined data processing.

[0045] The storage media of the controller unit 120 and the data processing unit 130 may include, for example, ROM, floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM, or non-volatile memory card.

[0046] Controller unit 120 can be configured and / or arranged for use 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, each controller unit 120 being configured to handle specific aspects and / or functions, and / or process data for generating models that are only used for a specific medical imaging system 100. In some implementations, 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, controller unit 120 may be remote and therefore accessible only via a remote connection (e.g., via the Internet or other available remote access technologies). In a particular implementation, controller unit 120 may be configured in a cloud-like manner and may be accessed and / or used in a manner substantially similar to that used for accessing and using other cloud-based systems.

[0047] The MRI system 100 also includes a detection bed 140 for carrying and / or moving the subject 116. The subject 116 can be moved into or out of the imaging space by moving the detection bed 140 based on control signals from the controller unit 120.

[0048] The MRI system 100 also includes an operation console unit 150 connected to the controller unit 120. The operation console unit 150 can send acquired operation signals to the controller unit 120 to control the operating status of components such as the examination table 140 and the scanner 110. These operation signals may include, for example, scanning protocols and parameters selected manually or automatically. The scanning protocol may include the aforementioned imaging sequence. Furthermore, the operation console unit 150 can send acquired operation signals to the controller unit 120 to control the data processing unit 130 to obtain the desired image.

[0049] The operation console unit 150 may include user input devices, such as a keyboard, mouse, voice-activated controller, or any other suitable input device, through which the operator can input operation signals / control signals to the controller unit 120.

[0050] The MRI system 100 may also include a display unit 160, which can be connected to the operation console unit 150 to display an operation interface, and can also be connected to the data processing unit 130 to display images.

[0051] In some embodiments, system 100 may 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 virtual private networks.

[0052] Before the formal imaging scan, it is necessary to identify the region of interest (ROI) of the object being examined, i.e., the location of the part to be examined, and move the examination bed so that the part to be examined is located at the center of the scanning cavity. Therefore, some embodiments of the present invention provide a positioning device for a magnetic resonance imaging system. This positioning device may be a controller unit 120 or a part of a controller unit 120, or it may be a separate device.

[0053] Figure 2 A schematic diagram of a positioning device 200 for a magnetic resonance imaging system according to some embodiments of the present invention is shown. Figure 2 As shown, the positioning device 200 includes a parameter acquisition module 210, a part determination module 220, and a control module 230. The parameter acquisition module 210 is used to acquire the scattering parameters (S-parameters) curve of the volume coil during the process of the detection bed carrying the object being detected entering the scanning cavity of the magnetic resonance imaging system. The part determination module 220 is used to acquire the position of the part to be detected of the object based on the scattering parameter curve. The control module 230 is used to move the detection bed based on the position of the part to be detected so that the part to be detected is located at the center of the scanning cavity.

[0054] Specifically, the scattering parameter curve is generated based on multiple scattering parameters corresponding to different positions of the object being detected in the scanning cavity.

[0055] The process of acquiring multiple scattering parameters occurs during the localization scan, which takes place before the formal imaging scan. In some embodiments, this localization scan may be performed during the pre-scanning phase.

[0056] Typically, S-parameters reflect the variation in load within the body coil. Load refers to different locations of the object being tested within the area covered by the body coil. Since the proportion of fat and / or muscle or other parameters varies at different locations of the object being tested, the load at different locations also varies. Therefore, the S-parameters corresponding to different locations are different.

[0057] Figure 3 This diagram illustrates the S-parameter values ​​corresponding to different parts of multiple tested objects. For example... Figure 3 As shown, the horizontal axis represents different body parts, and the vertical axis represents the S-parameters. The four sets of data corresponding to each body part represent four different objects being detected, from left to right representing the first, second, third, and fourth objects being detected, respectively. Figure 3The data shown are S-parameter values ​​without local and surface coils. Although the S-parameter values ​​for the same location (e.g., chest) differ for the four subjects, the minimum S-parameter value for each subject is between the navel and hip, i.e., the lower abdomen.

[0058] Specifically, the scattering parameters are obtained based on the reflected power and output power of the body coil when the object being detected is located at different positions in the scanning cavity. Specifically, the parameter acquisition module 210 is further configured to apply a preset input power to the body coil, monitor the output power and reflected power of the body coil when the object being detected is located at different positions, and obtain the scattering parameters corresponding to different positions based on the ratio of reflected power to output power.

[0059] In some embodiments, the preset input power is a small power, much smaller than the power applied to the body coil during the actual imaging scan. This preset input power can be applied to the body coil via an RF transmission link. The input power is continuously applied as the detection bed moves into the scanning cavity to obtain the S-parameters corresponding to different positions as the detection bed carries the object to be inspected. Continuous application can be applied continuously without interruption, or at intervals based on certain time intervals or the distance the detection bed moves.

[0060] Specifically, output power refers to the power output by the body coil to the environment (the space inside the scanning cavity), and reflected power refers to the power reflected from the environment back to the body coil. By setting a monitoring module at the output end of the body coil, the output power and reflected power of the body coil can be acquired in real time. The S-parameters can be calculated from the transmitted power and output power. In some embodiments, although the output power and reflected power are monitored separately, they can be implemented in the same hardware.

[0061] Specifically, the scattering parameter curve is generated by multiple S-parameters, each corresponding to a different position of the detection bed, which in turn corresponds to a different position of the object being detected. When the detection bed begins to enter the scanning cavity (or body coil), for example, but not limited to, entering 1 cm, input power is applied and the output power and reflected power of the body coil are monitored to obtain the S-parameter corresponding to that position. Then, when entering 2 cm, the S-parameter corresponding to that position is obtained, and so on until the end of the detection bed enters the scanning cavity. Connecting the multiple obtained S-parameters according to their positions yields the scattering parameter curve.

[0062] In some embodiments, the S-parameters are obtained at intervals of a preset distance the detection bed moves. The preset distance can be set relatively large to quickly obtain the S-parameters and thus determine the position of the part to be detected. Alternatively, the preset distance can be set relatively small to accurately obtain the precise position of the part to be detected.

[0063] Figure 4 A schematic diagram of the scattering parameter curves of the detected object is shown in the absence of surface coils and local coils. For example... Figure 4 As shown, Figure 4 The S-parameter curve shown is Figure 3 The histograms of the S-parameters shown have similar trends and general shapes. The S-parameter values ​​are smallest in the lower abdomen (the area between the navel and the hip) of the tested subject. Figure 4 The trough position 301 in the scattering parameter curve corresponds to the lower abdomen of the object being tested.

[0064] Therefore, the part determination module 220 can be used to obtain the distance between the head or foot and the lower abdomen of the object being detected based on the trough position in the scattering parameter curve, and to estimate the distance between the head or foot and the part to be detected based on the distance between the head or foot and the lower abdomen, so as to obtain the position of the part to be detected.

[0065] Because the S-parameters obtained by the body coil are significantly different between loaded and unloaded states, meaning that the S-parameters will change when a detected object begins to enter the scanning cavity, the position of the head or feet can be obtained.

[0066] The orientation of the object being detected varies; it may enter the scanning cavity head-first or foot-first. In some embodiments, when the head enters the scanning cavity first, the distance between the head and the area to be detected can be determined by measuring the distance between the head and the lower abdomen. Similarly, when the feet enter the scanning cavity first, the distance between the feet and the area to be detected can be determined by measuring the distance between the feet and the lower abdomen. In other embodiments, regardless of the orientation of the object, the distance between the head and the area to be detected can be determined by measuring the distance between the head and the lower abdomen. In still other embodiments, regardless of the orientation of the object, the distance between the feet and the area to be detected can be determined by measuring the distance between the feet and the lower abdomen.

[0067] Specifically, once the distance between the head and lower abdomen is obtained through the scattering parameter curve, for example, 80cm, and assuming the area to be detected is the chest, since the chest is roughly located between the head and lower abdomen, the distance between the chest and head can be determined to be approximately 40cm. Therefore, the position of the chest relative to the detection bed can also be obtained accordingly. The estimated distance between the head and the area to be detected can be based on information about the subject, such as height and weight, or it can be estimated based on the average proportions between different body parts.

[0068] Figure 5A schematic diagram of the scattering parameter curves of the detected object in the presence of a local coil is shown. Figure 5 As shown, the presence of local coils can significantly affect the S-parameters of the body coil, for example... Figure 5 As shown, peak 302 appears, and the location of peak 302 is the location of the local coil. Since the local coil is basically set or placed on the part to be detected, the location of the local coil is the location of the part to be detected.

[0069] Specifically, a peak is a position where the values ​​of the two adjacent positions are both smaller than that position.

[0070] Therefore, the location determination module 220 is further used to determine the location of the local coil based on the peak position in the scattering parameter curve, and the location of the local coil is the location of the location to be detected.

[0071] Figure 6 A schematic diagram of the scattering parameter curves of the detected object in the presence of surface coils is shown. Figure 6 As shown, the presence of surface coils can significantly affect the S-parameters of the body coil, for example... Figure 6 As shown, a first trough 303 and a second trough 305 appear. The position corresponding to the first trough 303 is where the surface head and neck coil is placed, while the position of the second trough 305 is where the surface belly coil (e.g., a blanket surface coil) is placed.

[0072] Specifically, a trough is a position where the values ​​of the two adjacent positions are both greater than that position.

[0073] The location of the trough 303 / 305 is the position of the surface coil. Since the surface coil is basically set or placed on the part to be tested, the position of the surface coil is the position of the part to be tested.

[0074] Therefore, the location determination module 220 is further used to determine the location of the surface coil based on the trough location in the scattering parameter curve, and the location of the surface coil is the location of the location to be detected.

[0075] although Figure 7 The figure shows the scattering parameter curves obtained when two surface coils are present simultaneously. However, those skilled in the art should understand that the two surface coils do not necessarily have to be present at the same time, and only one surface coil may be used.

[0076] Therefore, when a local coil or surface coil is set during scanning, the system will provide a corresponding prompt because the local coil or surface coil is connected to the magnetic resonance imaging system via an interface. This prompt helps distinguish between the similarity in the shape of the S-parameter curves obtained with and without a local coil or surface coil. Even without a prompt indicating that a local coil or surface coil is connected, the range of minimum S-parameter values ​​obtained with and without a local coil or surface coil can differ significantly, and the local coil and surface coil can be distinguished by the shape of their S-parameter curves.

[0077] In some embodiments, the control module 230 is further configured to stop the movement of the detection bed when the peak or trough position in the scattering parameter curve is obtained, so as to further simplify the process and improve efficiency. In some embodiments, the control module 230 is further configured to stop the movement of the detection bed when the position of the local coil or surface coil is obtained, so that the local coil or surface coil stays at the center of the scanning cavity. The range of minimum values ​​of S-parameters with and without coils and with surface coils can be obtained through experiments or experience. Therefore, when the obtained S-parameter is within a preset range, and the S-parameter values ​​corresponding to its adjacent positions are all greater than the S-parameter values ​​corresponding to that position, it can be confirmed that the position is the position corresponding to the minimum value, i.e., the trough position.

[0078] Figure 7 A flowchart of a localization method 400 for a magnetic resonance imaging system according to some embodiments of the present invention is shown. For example... Figure 7 As shown, the positioning method 400 includes steps 410, 420 and 430.

[0079] In step 410, during the process of the detection bed carrying the object being detected entering the scanning cavity of the magnetic resonance imaging system, the scattering parameter curve of the body coil is acquired.

[0080] Specifically, the acquisition of the scattering parameter curves of the volume coil occurs during the localization scan, which precedes the formal imaging scan. In some embodiments, the localization scan may be part of a pre-scan.

[0081] The scattering parameter curve is obtained by plotting multiple scattering parameters, each corresponding to a different position of the object being detected in the scanning cavity. In some embodiments, the S-parameter is acquired at intervals of a preset distance the detection bed moves. This preset distance can be set relatively large to quickly acquire the S-parameter and thus determine the position of the part to be detected, or it can be set relatively small to accurately acquire the precise position of the part to be detected.

[0082] Figure 8 It shows Figure 7 The flowchart illustrates the specific process of obtaining the scattering parameter curves of the volume coil in the positioning method shown.Figure 8 As shown, obtaining the scattering parameter curve of the volume coil further includes steps 411 and 412.

[0083] In step 411, the scattering parameters are acquired when the object being detected is located at different positions in the scanning cavity.

[0084] In step 412, the scattering parameter curves are generated based on the scattering parameters obtained at the different locations.

[0085] Specifically, obtaining scattering parameters at different locations includes obtaining the scattering parameters of the body coil based on the reflected power and output power of the body coil when the object being detected is located at the different locations.

[0086] In some embodiments, step 411 further includes steps 401, 402 and 403.

[0087] In step 401, a preset input power is applied to the body coil.

[0088] Specifically, the preset input power is a relatively small power, much smaller than the power applied to the body coil during the actual imaging scan. The input power is applied to the body coil via the radio frequency transmission link. The input power is continuously applied as the detection bed moves into the scanning cavity to obtain the S-parameters corresponding to different positions of the detection bed (different parts of the object being detected).

[0089] In step 402, the output power and reflected power of the monitoring coil are measured when the object being detected is located at different positions.

[0090] Specifically, the output power and reflected power of the body coil can be obtained through a monitoring module located at the output end of the body coil.

[0091] In step 403, scattering parameters corresponding to different locations are obtained based on the ratio of reflected power to output power.

[0092] Please return to the reference. Figure 7 In step 420, the location of the part to be detected of the object is obtained based on the scattering parameter curve.

[0093] In some embodiments, obtaining the location of the part to be detected of the object to be detected includes obtaining the distance between the head or foot and the lower abdomen of the object to be detected based on the trough position in the scattering parameter curve, and estimating the distance between the head or foot and the part to be detected based on the distance between the head or foot and the lower abdomen, so as to obtain the location of the part to be detected.

[0094] Specifically, assuming the area to be detected is the chest, after obtaining the distance between the head and lower abdomen through the scattering parameter curve, the position of the chest relative to the detection bed can also be obtained, since the chest is roughly located in the middle of the head and lower abdomen, approximately halfway between them. The estimated distance between the head and the area to be detected can be based on information about the subject, such as height and weight, or it can be estimated based on the average proportions between different body parts.

[0095] In other embodiments, obtaining the location of the part to be detected of the object to be detected includes determining the location of the local coil or the surface coil based on the peak or trough position in the scattering parameter curve, and the location of the local coil or the surface coil is the location of the part to be detected.

[0096] In step 430, based on the position of the part to be detected, the detection bed is moved so that the part to be detected is located at the center of the scanning cavity.

[0097] In some embodiments, the movement of the detection bed is stopped when a peak or trough in the scattering parameter curve is obtained, thereby further simplifying the process and improving efficiency. In some embodiments, the movement of the detection bed is stopped when the position of the local coil or surface coil is obtained, so that the local coil or surface coil remains at the center of the scanning cavity.

[0098] In summary, the positioning method of the magnetic resonance imaging system in some embodiments of the present invention can obtain the position of the part to be detected of the object by monitoring and acquiring the scattering parameter curve of the body coil, and then move the detection bed so that the part to be detected is located at the center of the scanning cavity, so as to achieve automatic positioning or one-click positioning. No other equipment needs to be installed, which not only simplifies the process and reduces the cost, but also allows the operator not to stay in the scanning room to perform the positioning operation.

[0099] The present invention may also provide a non-transitory computer-readable storage medium for storing an instruction set and / or a computer program that, when executed by a computer, causes the computer to perform the above-described method for acquiring a truncated portion of the predicted image. The computer executing the instruction set and / or the computer program may be a computer of an MRI system or other devices / modules of an MRI system. In one embodiment, the instruction set and / or the computer program may be programmed into the processor / controller of the computer.

[0100] Specifically, when this instruction set and / or computer program is executed by the computer, it causes the computer to:

[0101] During the process of the detection bed carrying the object being detected entering the scanning cavity of the magnetic resonance imaging system, the scattering parameter curve of the volume coil is acquired;

[0102] Based on the scattering parameter curve, the location of the part to be detected in the object being detected is obtained; and

[0103] Based on the location of the part to be detected, the detection bed is moved so that the part to be detected is located at the center of the scanning cavity.

[0104] As described above, instructions can be combined into a single instruction for execution, or any instruction can be split into multiple instructions for execution. Furthermore, the execution order of instructions is not limited to that described above.

[0105] As used herein, the term "computer" can include any processor-based or microprocessor-based system, including systems that use microcontrollers, reduced instruction set computers (RISC), application-specific integrated circuits (ASICs), logic circuits, and any other circuitry or processors capable of performing the functions described herein. The examples above are merely illustrative and are not intended to limit the definition and / or meaning of the term "computer" in any way.

[0106] The instruction set may include various commands that instruct a computer or processor, acting as a processor, to perform specific operations, such as methods and processes according to various embodiments. The instruction set may take the form of a software program, which may be part of one or more tangible, non-transitory computer-readable media. The software may take various forms, such as system software or application software. Furthermore, the software may take the form of a collection of independent programs or modules, a program module within a larger program, or part of a program module. The software may also include modular programming in the form of object-oriented programming. Input data processing by the processor may be in response to operator commands, previous processing results, or requests made by another processor.

[0107] Some exemplary embodiments have been described above; however, it should be understood that various modifications can be made. For example, suitable results may be achieved if the described techniques are performed in a different order and / or if components in the described system, architecture, device, or circuit are combined in a different manner and / or replaced or supplemented by other components or their equivalents. Accordingly, other embodiments also fall within the scope of the claims.

Claims

1. A positioning method of a magnetic resonance imaging system, comprising: obtaining a scatter parameter curve of a body coil during a process in which a detection bed carrying a detected object enters a scanning cavity of the magnetic resonance imaging system; obtaining a position of a to-be-detected part of the detected object based on the scatter parameter curve; and moving the detection bed based on the position of the to-be-detected part so that the to-be-detected part is located at a center of the scanning cavity; wherein the obtaining of the scatter parameter curve of the body coil comprises: obtaining the scatter parameters when the detected object is located at different positions of the scanning cavity; and generating the scatter parameter curve based on the scatter parameters obtained when the detected object is located at the different positions.

2. The positioning method of claim 1, wherein, The obtaining of the scatter parameters when the detected object is located at the different positions comprises obtaining the scatter parameters of the body coil based on reflected power and output power of the body coil when the detected object is located at the different positions.

3. The positioning method of claim 2, wherein, The obtaining of the scatter parameters when the detected object is located at the different positions further comprises: applying a preset input power to the body coil; monitoring the output power and the reflected power of the body coil when the detected object is located at the different positions; and obtaining the scatter parameters corresponding to the different positions based on a ratio of the reflected power to the output power.

4. The positioning method of claim 1, wherein, The obtaining of the position of the to-be-detected part of the detected object comprises: determining a position of a local coil or a surface coil based on a position of a wave peak or a wave trough in the scatter parameter curve, and the position of the local coil or the surface coil is the position of the to-be-detected part.

5. The positioning method of claim 1, wherein, The obtaining of the position of the to-be-detected part of the detected object comprises: obtaining a distance between a head or a foot of the detected object and a lower abdomen based on a position of a wave trough in the scatter parameter curve; and estimating a distance between the head or the foot and the to-be-detected part based on the distance between the head or the foot and the lower abdomen to obtain the position of the to-be-detected part. 6.A non-transitory computer-readable storage medium for storing a computer program, the computer program causing a computer to execute the positioning method of the magnetic resonance imaging system according to any one of claims 1-5 when executed by the computer. 7.A magnetic resonance imaging system, comprising: a main magnet, an inside of which defines a scanning cavity; a body coil for transmitting or receiving radio frequency signals; a detection bed for carrying and moving a to-be-detected object; and a positioning device, comprising: a parameter obtaining module for obtaining a scatter parameter curve of a body coil during a process in which a detection bed carrying a detected object enters a scanning cavity of the magnetic resonance imaging system; a part determining module for obtaining a position of a to-be-detected part of the detected object based on the scatter parameter curve; and a control module for moving the detection bed based on the position of the to-be-detected part so that the to-be-detected part is located at a center of the scanning cavity; wherein the scatter parameters are obtained based on reflected power and output power of the body coil when the detected object is located at different positions of the scanning cavity. The parameter obtaining module is further configured to:

8. The magnetic resonance imaging system of claim 7, wherein, apply a preset input power to the body coil; monitor the output power and the reflected power of the body coil when the detected object is located at the different positions; and obtain the scatter parameters corresponding to the different positions based on a ratio of the reflected power to the output power. Based on a ratio of the reflected power and the output power, a scattering parameter corresponding to the different positions is obtained.

9. The magnetic resonance imaging system of claim 7, wherein, The site determination module is further configured to determine a position of a local coil or a surface coil based on a position of a wave peak or a wave trough in the scattering parameter curve, and the position of the local coil or the surface coil is the position of the to-be-detected site.

10. The magnetic resonance imaging system of claim 7, wherein, The site determination module is further configured to obtain a distance between a head or a foot and a lower abdomen of the detected object based on a position of a wave trough in the scattering parameter curve, and calculate a distance between the head or the foot and the to-be-detected site based on the distance between the head or the foot and the lower abdomen, to obtain the position of the to-be-detected site.

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