Magnetic resonance imaging method and magnetic resonance imaging system

Abstract

The invention relates to a magnetic resonance imaging method and a magnetic resonance imaging system, and the method comprises the steps: obtaining an initial inversion recovery scanning sequence which comprises an inversion module and an imaging collection module; obtaining first gradient coding position information of a set tissue of the target scanning part according to an imaging acquisition module; according to the first gradient coding position information, gradient coding parameters of an inversion module are determined, and a target inversion recovery scanning sequence is obtained; and scanning the target scanning part according to the target inversion recovery scanning sequence to obtain a magnetic resonance image. By adopting the method, the problem that a fat inhibition method cannot have a relatively good inhibition effect in various occasions can be solved.

Description

Technical Field

[0001] This application relates to the field of magnetic resonance imaging, and in particular to magnetic resonance imaging methods and magnetic resonance imaging systems. Background Technology

[0002] Magnetic resonance imaging (MRI) boasts advantages such as high spatial resolution, superior soft tissue contrast, and no ionizing radiation, making it a crucial tool in clinical medical auxiliary diagnosis. MRI can provide various contrast imaging methods, such as T1-weighted, T2-weighted, and PD (proton density)-weighted imaging. In clinical applications, multiple contrast images are often combined for auxiliary diagnosis. Fat suppression techniques can reduce motion artifacts, chemical artifacts, or other artifacts; they can also increase tissue contrast, differentiate tumors, and improve lesion detection rates. Fat suppression techniques are significant and indispensable in MRI. Conventional fat suppression scanning methods mainly fall into the following categories: First, frequency-selective fat suppression. This method suppresses only the fat signal through frequency selection. It is sensitive to both the B0 and B1 values ​​of the MRI sequence's emission system. For example, if the B0 value is uneven or the frequency selection does not target the fat signal, fat suppression will fail. Second, inversion-recovery fat suppression. This method inverts all signals. After a period of recovery, the fat signal returns to zero, while other tissue signals remain non-zero, thus achieving fat suppression.

[0003] In the process of fat suppression using related technologies, the resonance frequency of fat differs from the resonance frequency of the excited protons at different detection locations or different detection sites of the same detection subject. This difference leads to a discrepancy between the chemical shift of fat when the inversion pulse of the inversion module of the magnetic resonance imaging (MRI) sequence is applied and the chemical shift of fat location when the radio frequency pulse of the imaging module of the MRI sequence is applied, resulting in a deterioration in fat suppression effectiveness. Furthermore, for radio frequency modules with different slice thicknesses in the slice selection direction and imaging pulses with different parameters, the chemical shift of fat location in the slice direction varies. Therefore, the fat suppression effect varies under different conditions.

[0004] There is currently no effective solution to the problem that existing fat inhibition methods cannot achieve good inhibition effects in all situations. Summary of the Invention

[0005] Therefore, it is necessary to provide a magnetic resonance imaging method and system that can solve the problem that fat suppression methods cannot achieve good suppression effects in all situations, in order to address the above-mentioned technical problems.

[0006] Firstly, this embodiment provides a magnetic resonance imaging method, the method comprising:

[0007] Acquire an initial inverted recovery scan sequence, the sequence including an inverting module and an imaging acquisition module;

[0008] According to the imaging acquisition module, the first gradient encoding location information of the set tissue at the target scanning site is obtained;

[0009] Based on the first gradient encoding position information, the gradient encoding parameters of the inversion module are determined to obtain the target inversion recovery scan sequence;

[0010] The target scanning region is scanned according to the target inversion recovery scanning sequence to obtain a magnetic resonance image.

[0011] In some embodiments, obtaining the first gradient-coded location information of a predetermined tissue at the target scanning site based on the imaging acquisition module includes:

[0012] Based on the excitation pulse and / or refocusing pulse in the imaging acquisition module, a first excitation region corresponding to the set tissue in the imaging acquisition module is obtained, and the first excitation region is used as the first gradient encoding position information.

[0013] In some embodiments, determining the gradient encoding parameters of the inversion module based on the first gradient encoding position information includes:

[0014] Based on the first gradient encoding position information, the second gradient encoding position information of the set organization corresponding to the inversion module is obtained;

[0015] The gradient encoding parameters of the inversion module are determined based on the second gradient encoding position information.

[0016] In some embodiments, obtaining second gradient encoding position information of a set organization corresponding to the inversion module based on the first gradient encoding position information, and determining the gradient encoding parameters of the inversion module based on the second gradient encoding position information, includes:

[0017] The second excitation region of the set tissue in the inversion module is obtained according to the first gradient encoding position information, so as to obtain the second gradient encoding position information; wherein, the overlap range between the second excitation region and the first excitation region satisfies a preset condition;

[0018] The layer selection gradient position information of the inversion module is determined based on the second gradient encoding position information.

[0019] In some embodiments, the method further includes:

[0020] The gradient magnetic field strength of the inversion module is obtained based on the second gradient encoding position information;

[0021] The bandwidth of the adiabatic pulse contained in the inversion module is obtained based on the gradient magnetic field strength and the selected layer gradient position information.

[0022] In some embodiments, determining the layer selection gradient position information of the inversion module based on the second gradient encoding position information includes:

[0023] The layer position of the inversion module is determined by the second gradient encoding position information;

[0024] The layer thickness selected by the imaging acquisition module is obtained based on the first gradient encoding position information;

[0025] The layer thickness information of the inversion module is determined based on the layer position and the layer thickness selected by the imaging acquisition module; wherein the layer thickness of the inversion module is greater than or equal to the layer thickness selected by the imaging acquisition module.

[0026] In some embodiments, the method further includes:

[0027] The amplitude of the inversion pulse in the inversion module is obtained based on the radio frequency emission intensity of the radio frequency field corresponding to the target scanning area.

[0028] In some embodiments, the method further includes:

[0029] Obtain the threshold value of the specific absorption rate of the target scanning area to electromagnetic radiation;

[0030] The radio frequency energy of the inversion module is obtained based on the threshold, so that when the inversion module is applied to the target scanning area, the specific absorption rate caused by the radio frequency energy is less than the threshold of the specific absorption rate.

[0031] In some embodiments, the method further includes:

[0032] The uniformity of the radio frequency field corresponding to the target scanning area is evaluated;

[0033] The gradient coding parameters of the inversion module are adjusted according to the evaluation results so that the change in the flip angle of the inversion module within the radio frequency field is less than or equal to a specified change value.

[0034] Secondly, this embodiment provides a magnetic resonance imaging system, the system comprising:

[0035] Scanner;

[0036] The controller is configured to perform the following steps:

[0037] An imaging acquisition module to be executed on the target scanning area is obtained, the imaging acquisition module including an excitation pulse and a convergence pulse;

[0038] According to the imaging acquisition module, the first gradient encoding location information of the target scanning area is determined, wherein the set tissue is adipose tissue;

[0039] Based on the first gradient encoding position information, gradient encoding parameters are set for the inversion module to obtain the target inversion recovery scan sequence, and the inversion module is applied in front of the imaging acquisition module;

[0040] The scanner is controlled to apply the target inversion recovery scan sequence to the target scan area to obtain a magnetic resonance image.

[0041] The aforementioned magnetic resonance imaging method and system determine the gradient coding parameters of the inversion module based on the first gradient coding position information of the set tissue corresponding to the imaging acquisition module in the initial inversion recovery scan sequence. This ensures that the gradient coding parameters of the inversion module are compatible with the position of the set tissue obtained when the imaging pulse is applied, thereby improving the fat suppression effect of the magnetic resonance sequence. Furthermore, the method is applicable to various magnetic resonance sequences with fat suppression functions, thus solving the problem that existing fat suppression methods cannot achieve good suppression effects in all situations. Attached Figure Description

[0042] Figure 1 This is a diagram illustrating the application environment of a magnetic resonance imaging method in one embodiment.

[0043] Figure 2 This is a schematic flowchart of a magnetic resonance imaging method in one embodiment;

[0044] Figure 3 This is a schematic diagram of the reverse recovery scan sequence in one embodiment;

[0045] Figure 4 This is a flowchart illustrating a method for generating a reverse recovery scan sequence in one embodiment;

[0046] Figure 5 This is a schematic diagram of adapting the inversion pulse according to the excitation pulse in one embodiment;

[0047] Figure 6 This is a schematic diagram of adapting a retraction pulse to a reversal pulse in one embodiment;

[0048] Figure 7 This is a schematic diagram of adapting the inversion pulse according to the excitation pulse and the retraction pulse in one embodiment;

[0049] Figure 8This is a schematic diagram of the inverted pulse bandwidth in one embodiment;

[0050] Figure 9 This is a schematic diagram of the inverted pulse amplitude in one embodiment;

[0051] Figure 10 This is a schematic diagram of a magnetic resonance image obtained based on a traditional fat suppression method.

[0052] Figure 11 This is a schematic diagram of a magnetic resonance image in one embodiment;

[0053] Figure 12 This is a structural block diagram of a magnetic resonance imaging device in one embodiment;

[0054] Figure 13 This is an internal structural diagram of a computer device in one embodiment. Detailed Implementation

[0055] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0056] The magnetic resonance imaging method provided in this application embodiment can be applied to, for example... Figure 1 In the application environment shown, terminal 102 communicates with server 104 via a network. A data storage system stores the data that server 104 needs to process. The data storage system can be integrated onto server 104 or located in the cloud or on other network servers. After obtaining parameters from terminal 102 or between terminal 102 and server 104, the target inversion recovery scan sequence is determined and stored in the data storage system. Terminal 102 can be, but is not limited to, various personal computers, laptops, tablets, etc. Server 104 can be implemented using a standalone server or a server cluster consisting of multiple servers.

[0057] In one embodiment, such as Figure 2 As shown, a magnetic resonance imaging method is provided, which is applied to... Figure 1 Taking terminal 102 as an example, the explanation includes the following steps:

[0058] Step 202: Obtain the initial inversion recovery scan sequence, which includes the inversion module and the imaging acquisition module.

[0059] The initial inversion recovery scan sequence is a pulse sequence used to achieve fat suppression imaging. The imaging acquisition module is the module in the initial inversion recovery scan sequence that directly participates in exciting hydrogen nuclei to generate magnetic resonance signals; the parameters of the imaging acquisition module can be obtained according to the requirements of fat suppression imaging. The inversion module is the module in the initial inversion recovery scan sequence used to invert the magnetization vectors of all tissues in the target scanning area. The designated tissue is the fat that needs to be suppressed during magnetic resonance imaging of the target scanning area. Due to the difference in relaxation characteristics between the designated and non-designated tissues, after a specified time, the magnetization vector of the designated tissue has not fully recovered before signal acquisition, while the non-designated tissue still has a high magnetization vector value. Therefore, the initial inversion recovery scan sequence can achieve the effect of fat suppression.

[0060] Step 204: Based on the imaging acquisition module, obtain the first gradient encoding location information of the set tissue of the target scanning area.

[0061] The first gradient encoding position information can be set to the gradient encoding position applied to the adipose tissue by the excitation pulse in the imaging acquisition module; the first gradient encoding position information can also be set to the gradient encoding position applied to the adipose tissue by the retraction pulse in the imaging acquisition module. Both the gradient encoding position applied to the adipose tissue by the excitation pulse and the gradient encoding position applied to the adipose tissue by the retraction pulse can be set through the user interface.

[0062] Optionally, the parameters of the imaging acquisition module are obtained according to the detection purpose of the target scanning area. Based on the frequency band range of the pulse in the parameters of the imaging acquisition module, the protons that are within the frequency band range and will be excited by resonance are determined. The location of the set tissue is calculated based on the excited protons.

[0063] Step 206: Determine the gradient encoding parameters of the inversion module based on the first gradient encoding position information to obtain the target inversion recovery scan sequence.

[0064] The gradient encoding parameters of the inversion module include slice gradient location information (slice location, slice thickness), pulse bandwidth, amplitude, etc. Because conventional 2D multilayer imaging sequences typically employ selective excitation techniques in the imaging acquisition module, the difference between the resonant frequency of the target tissue and the resonant frequency of protons within the resonant frequency band will cause chemical shift of the target tissue in the slice selection direction. Therefore, during fat suppression based on the initial inversion recovery scan sequence, the position of the target tissue obtained when applying the inversion pulse may differ from the position obtained when applying the imaging pulse, potentially resulting in poor fat suppression performance of the initial inversion recovery scan sequence.

[0065] Different gradient encoding parameters of the inversion module result in different locations of the target tissue excited by the inversion module. Specifically, to improve the fat suppression effect of the initial inversion recovery scan sequence, the gradient encoding parameters of the inversion module can be obtained based on the first gradient encoding location information, ensuring that the location information of the target tissue excited by the inversion module matches the location information of the target tissue excited by the imaging module.

[0066] Step 208: Scan the target scanning area according to the target inversion recovery scanning sequence to obtain a magnetic resonance image. Optionally, apply the target inversion recovery scanning sequence to the target scanning area and reconstruct the magnetic resonance image based on the scanning results.

[0067] In the aforementioned magnetic resonance imaging method, the first gradient coding position information of the target tissue is obtained from the imaging module in the initial inversion recovery scan sequence. The gradient coding parameters of the inversion module are then obtained based on this first gradient coding position information. By adjusting the gradient coding parameters of the inversion module, the position of the target tissue excited by the inversion module can be adjusted to ensure that the target tissue obtained from the inversion module matches the first gradient coding position information corresponding to the applied imaging module. This results in a target inversion recovery scan sequence containing the imaging module and the adjusted parameters. Inversion recovery imaging based on this target inversion recovery scan sequence exhibits good suppression effects. Furthermore, this method is not limited by the detection object or the detection environment, solving the problem that existing fat suppression methods cannot achieve good suppression effects in all situations.

[0068] In one embodiment, obtaining the first gradient-coded position information of a designated tissue at the target scanning site according to the imaging acquisition module includes: obtaining the first excitation region corresponding to the designated tissue in the imaging acquisition module according to the excitation pulse and / or refocusing pulse in the imaging acquisition module, and using the first excitation region as the first gradient-coded position information.

[0069] The first gradient-coded location information includes, but is not limited to, setting the location, slice thickness, and size of the region of tissue excited by the imaging module. The imaging pulse in the imaging acquisition module can be a single excitation pulse, or a single excitation pulse and at least one convergence pulse, or multiple excitation pulses. Optionally, when the imaging sequence includes multiple pulses, multiple first gradient-coded location information corresponding to each pulse can be obtained. Figure 3 A schematic diagram of a reverse recovery scan sequence is provided, such as... Figure 3 As shown, RF refers to radio frequency pulses, and G... SS The gradient G is used to select the direction of the slice. PE G is the gradient in the phase encoding direction. ROTo read the gradient in the gradient direction, ECHO represents time, TI represents the time interval between the 180° pre-pulse and the 90° excitation pulse (i.e., the inversion time), and TR represents the repetition time. The IR section is an inversion module that includes the inversion pulse, and the imaging acquisition section is an imaging module that includes the imaging pulse. Figure 3 In the imaging acquisition section of a magnetic resonance sequence, the RF pulses are the imaging pulses. The imaging acquisition section includes one excitation pulse and multiple convergence pulses.

[0070] In this embodiment, the chemical shift of the magnetic resonance signal in the layer selection direction, i.e. the first gradient encoded position information, is determined by the excitation pulse and / or refocusing pulse used in the imaging module, so that the magnetic resonance imaging method can be applied to imaging sequences in various situations.

[0071] In one embodiment, determining the gradient encoding parameters of the inversion module based on the first gradient encoding position information includes: obtaining the second gradient encoding position information of the set organization corresponding to the inversion module based on the first gradient encoding position information; and determining the gradient encoding parameters of the inversion module based on the second gradient encoding position information.

[0072] The second gradient-coded location information includes, but is not limited to, the location, slice thickness, and size of the region where the set tissue is excited by the inversion module. Optionally, the second gradient-coded location information is obtained based on the first gradient-coded location information, such that the overlap ratio between the location range in the first gradient-coded location information and the location range in the second gradient-coded location information is greater than a specified value, and the slice thickness in the first gradient-coded location information is greater than or equal to the slice thickness in the second gradient-coded location information. This ensures that the region where the set tissue is excited in the imaging module is included in the excitation region of the set tissue in the inversion module, thereby achieving a better fat suppression effect.

[0073] Optionally, after obtaining the corresponding first gradient-coded position information based on multiple pulses in the imaging pulse, second gradient-coded position information is acquired, ensuring that the range of the second gradient-coded position information overlaps with the ranges of the multiple first gradient-coded position information, and that the overlap ratio is greater than a specified value. The range corresponding to the slice thickness in the first gradient-coded position information includes multiple ranges corresponding to the slice thickness in the multiple second gradient-coded position information. The specified value corresponding to the overlap ratio can be set to a default value or set and modified by the user. The magnitude of the specified value determines the intensity of the target tissue (fat signal). A larger specified value results in a higher overlap ratio, a higher signal intensity of the target tissue excited by the inversion module, and a relatively better fat suppression effect; a smaller specified value results in a lower overlap ratio, a lower signal intensity of the target tissue excited by the inversion module, and a relatively poor fat suppression effect.

[0074] Further, in one embodiment, based on the first gradient encoding position information, a second gradient encoding position information of a set tissue corresponding to the inversion module is obtained; based on the second gradient encoding position information, the gradient encoding parameters of the inversion module are determined, including: obtaining a second excitation region of the set tissue in the inversion module based on the first gradient encoding position information to obtain the second gradient encoding position information; wherein the overlap range between the second excitation region and the first excitation region satisfies a preset condition; and determining the layer selection gradient position information of the inversion module based on the second gradient encoding position information.

[0075] The first excitation region is the area of ​​fat in the designated tissue region that is excited by pulses from the imaging module; the second excitation region is the area of ​​fat in the designated tissue region that is excited by pulses from the inversion module. The slice gradient position information may include, but is not limited to, the slice position, slice thickness, and gradient field intensity of the fat excited by the inversion module. A preset condition is used to indicate that the overlap between the region corresponding to the first gradient encoding position information and the preset region is sufficiently large. Optionally, the preset condition may be that the ratio between the overlap between the first and second excitation regions and the first excitation region is greater than a specified value, or that the area of ​​the aforementioned overlap is greater than a specified value. Optionally, when multiple first gradient encoding position information exist, the overlap between the region corresponding to each first gradient encoding position information and the preset region all satisfy the preset condition. In this embodiment, by adjusting the position of the preset region, the first and second gradient encoding position information are matched, thereby improving the fat suppression capability of the magnetic resonance sequence.

[0076] In one embodiment, the magnetic resonance imaging method further includes: obtaining the gradient magnetic field strength of the inversion module based on the second gradient encoded position information; and obtaining the bandwidth of the adiabatic pulse contained in the inversion module based on the gradient magnetic field strength and the slice selection gradient position information. The adiabatic pulse is used to invert the fat signal, and its use increases the robustness of signal inversion.

[0077] Optionally, the gradient magnetic field strength at the time of pulse application in the inversion module can be obtained based on the second gradient encoding position information; the position coordinates of the excited tissue in the direction of the selected gradient can be determined based on the layer selection gradient position information, thereby obtaining the layer thickness corresponding to the inversion module. The bandwidth Bw can be calculated based on the bandwidth calculation formula for the adiabatic pulse; where...

[0078] Bw=γ·Gz·h

[0079] γ is the gyromagnetic ratio, h is the slice thickness during imaging, and Gz is the gradient magnetic field strength.

[0080] Furthermore, considering that the slice thickness of pulse excitation in the imaging module is usually not a perfect rectangle, and there is some fat signal outside the slice thickness of excitation and refocusing excitation, in order to further improve the fat suppression capability of the magnetic resonance sequence, in one embodiment, the slice selection gradient position information of the inversion module is determined based on the second gradient coding position information, including: determining the slice position of the inversion module through the second gradient coding position information; determining the slice thickness information of the inversion module according to the slice position and the slice thickness selected by the imaging acquisition module; wherein, the slice thickness of the inversion module is greater than or equal to the slice thickness selected by the imaging acquisition module.

[0081] Optionally, the position coordinates of the tissue excited by the inversion module in the direction of the selected gradient can be determined based on the selected gradient position information, thereby obtaining the slice position corresponding to the inversion module. If the slice thickness of the inversion module is determined to be less than the slice thickness selected by the imaging acquisition module based on the slice position, the slice thickness information of the inversion module is adjusted based on the slice thickness selected by the imaging acquisition module so that the slice thickness of the inversion module is greater than or equal to the slice thickness selected by the imaging acquisition module.

[0082] Optionally, if single-segment imaging is used in the magnetic resonance imaging sequence, the slice thickness of the inversion module is greater than or equal to the slice thickness selected by the imaging acquisition module, ensuring that all signals excited by the imaging acquisition module are inverted. In multi-segment imaging, the slice thickness corresponding to the inversion module can be obtained by comprehensively considering the interval between adjacent imaging layers. For example, the slice thickness of the inversion module can be set to be less than the interval between adjacent imaging layers. Optionally, the slice thickness can be changed by adjusting the amplitude and duration of the slice selection gradient field when the inversion pulse is applied in the inversion module. In this embodiment, after determining the slice thickness information of the inversion module through the second gradient encoding position information, the slice thickness of the inversion module is adjusted according to the slice thickness selected by the imaging acquisition module, so that the slice thickness of the inversion module is greater than or equal to the slice thickness selected by the imaging acquisition module, allowing the target inversion recovery scan sequence to invert all signals excited by the imaging acquisition module, ensuring that the magnetic resonance sequence has a good fat suppression effect.

[0083] In one embodiment, the magnetic resonance imaging method further includes: obtaining the amplitude of the inversion pulse in the inversion module based on the radio frequency emission intensity of the radio frequency field corresponding to the target scanning area.

[0084] The greater the radio frequency (RF) emission intensity, the greater the amplitude of the inversion pulse in the inversion module. Optionally, the amplitude of the inversion pulse is obtained based on the maximum RF emission intensity in the RF path corresponding to the target scanning area. In this embodiment, the amplitude of the inversion pulse is adapted to the RF emission intensity of the transmission system, making the magnetic resonance imaging method applicable to various magnetic resonance transmission systems. In ultra-high fields with different transmission systems, when switching between local transmission systems (such as the head and knee joint) and global transmission systems, the adaptive inversion module can adapt the pulse according to the maximum B1 value (RF emission intensity) of the transmission system to achieve better fat suppression performance.

[0085] Optionally, the magnetic resonance imaging method further includes: obtaining a threshold of the specific absorption rate of the target scanning area to electromagnetic radiation; and obtaining the radio frequency energy of the inversion module based on the threshold, so that when the inversion module is applied to the target scanning area, the specific absorption rate caused by the radio frequency energy is less than the threshold of the specific absorption rate.

[0086] Obtain the threshold of the specific absorption rate of the target scanning area to electromagnetic radiation; obtain the radio frequency energy of the reflected pulse in the inversion module based on the threshold, wherein when the magnetic resonance pulse is applied to the target scanning area, the specific absorption rate caused by the radio frequency energy is less than the threshold of the specific absorption rate.

[0087] Specifically, the higher the SAR (Specific Absorption Rate) threshold required for the target scanning area, the higher the radio frequency energy that the reflected pulse can be set; conversely, the lower the threshold, the lower the SAR threshold. Optionally, by adjusting pulse parameters related to radio frequency energy, such as pulse application duration, interval, and sequence, the energy of a single pulse can be adjusted so that the SAR of the target scanning area is less than the SAR threshold when the magnetic resonance pulse is applied. By adjusting the radio frequency energy of the reflected pulse, the level of electromagnetic radiation to the human body during magnetic resonance is changed, thereby improving the safety of magnetic resonance examinations based on magnetic resonance sequences.

[0088] Optionally, the magnetic resonance imaging method further includes: evaluating the uniformity of the radio frequency field corresponding to the target scanning area; and adjusting the gradient encoding parameters of the inversion module according to the evaluation results, so that the change value of the flip angle of the inversion module in the radio frequency field is less than or equal to a specified change value.

[0089] The inversion module can include an adiabatic pulse. Based on the uniformity assessment results, it adjusts parameters related to adiabatic properties, such as the length, shape, and amplitude of the adiabatic pulse, to achieve an effect where the change in the flip angle of the inversion pulse within the radio frequency field is less than or equal to a specified change value. This specified change value is obtained based on the uniformity of the radio frequency field. By adjusting the parameters of the inversion pulse, its performance in non-uniform radio frequency fields is optimized, improving the magnetic resonance imaging quality while maintaining image quality and enhancing the resistance of the magnetic resonance sequence to B1 field inhomogeneities.

[0090] In one embodiment, Figure 4 A method for generating an inversion recovery scan sequence is provided, which enables uniform fat suppression in different scenarios. The method includes the following steps:

[0091] Step 402: Obtain the pulse configuration of the imaging module in the magnetic resonance sequence. The specific pulse settings can vary depending on the application scenario. Specifically, each period of the magnetic resonance pulse sequence may contain one excitation pulse; or multiple excitation pulses; or one excitation pulse and one convergence pulse; or one excitation pulse and multiple convergence pulses.

[0092] Step 404: Adaptively configure the inversion pulse in the inversion module according to the pulse configuration of the imaging module.

[0093] When selective excitation is used to apply pulses to the imaging module at the imaging level: a layer-selective gradient is applied in the Z direction, and the proton precession frequency along the z-axis can be expressed as Wz = γ(B0 + zGz), where Wz is the proton Larmor frequency at a point along the z-axis; γ is the gyromagnetic ratio; B0 is the strength of the main magnetic field; z is the position coordinate of the proton along the z-axis; and Gz is the gradient magnetic field strength along the z-axis. With selective excitation, only protons with resonance frequencies within the radio frequency pulse band of the target scanning area can be excited. Because there is a difference between the resonance frequency of fat and that of protons, fat will exhibit chemical shift in the layer-selective direction. Therefore, variations in the layer thickness and imaging pulse of the radio frequency module will lead to inconsistent chemical shift magnitudes for each radio frequency module. If there is a difference in the fat position offset between the inversion module and the imaging module, it will result in differences in fat suppression. The imaging acquisition module includes excitation pulses, or imaging pulses such as excitation pulses and refocusing pulses; the inversion module includes inversion pulses.

[0094] In order to adaptively configure the reversal pulse, optionally, the chemical displacement of the set tissue excited by the reversal module in the layer direction is adapted according to the chemical displacement of the set tissue excited by the excitation pulse in the imaging module in the layer direction, that is, the second gradient coding position information of the fat when the reversal pulse is applied is determined according to the first gradient coding position information of the re-aggregated fat obtained after the excitation pulse is applied. Figure 5 A schematic diagram is provided showing how to adapt an excitation pulse to an inversion pulse. Here, IR represents the inversion pulse, Ex represents the excitation pulse in the imaging module, Ref represents the refocusing pulse in the imaging module, the vertical axis represents the position in the slice selection direction, and the horizontal axis represents the pulse application time.

[0095] Optionally, the chemical displacement of the set tissue excited by the re-polymerization pulse in the layer selection direction is adapted to the chemical displacement of the set tissue excited by the re-polymerization pulse in the layer selection direction, that is, the second gradient coding position information of the fat when the reversal pulse is applied is determined based on the first gradient coding position information of the re-polymerized fat obtained after the re-polymerization pulse is applied. Figure 6 A schematic diagram is provided for adapting a reciprocating pulse to a reciprocating pulse.

[0096] Optionally, the chemical displacement of the selected tissue excited by the inversion module in the layer selection direction is adapted according to the chemical displacement of the selected tissue excited by the excitation pulse and the re-polymerization pulse in the layer selection direction. That is, the second gradient coding position information of fat when the inversion pulse is applied is determined according to the first gradient coding position information of fat obtained after the application of the excitation pulse and the re-polymerization pulse. Figure 7 A schematic diagram is provided showing how to adapt the inversion pulse based on the excitation pulse and the retraction pulse.

[0097] By acquiring the second gradient encoding position information of fat when the inversion module applies a pulse to the target scanning area, the bandwidth BW of the inversion pulse can be obtained. Figure 8 This is a schematic diagram of the inverted pulse bandwidth in this embodiment, as shown below. Figure 8 As shown, the vertical axis represents the location of the fat, and the horizontal axis represents the frequency (Hz) of the inversion pulse.

[0098] Step 406: Obtain some parameters of the inversion module based on the limitations of the launch system.

[0099] Optionally, the amplitude of the inverted pulse is obtained by adapting the pulse to the maximum B1 value of the transmitting system. The maximum B1 values ​​of different transmitting systems are different, especially in ultra-high fields, where there may be switching between different transmitting systems. The adaptive inversion module can adapt the pulse to the maximum B1 value of the transmitting system. Figure 9 This is a schematic diagram of the amplitude of a reverse pulse in this embodiment, as shown below. Figure 9 As shown, the vertical axis represents the amplitude of the inverted pulse, and the horizontal axis represents the magnetic field strength.

[0100] Step 408: Obtain some parameters of the inversion module according to imaging requirements.

[0101] Optionally, the uniformity of B1 values ​​varies significantly across different parts of the same target scanning area, especially in ultra-high fields. Taking the human body as an example, when the target scanning area is the body, the scanning range is large and deep, making it difficult for radio frequency to penetrate, resulting in poor B1 value uniformity; the knee joint has a smaller range and more uniform B1 values. Therefore, based on the requirement for uniformity of B1 values ​​corresponding to the target scanning area, the thermal insulation of the inversion module can be adjusted to improve the fat suppression performance of the magnetic resonance sequence. Alternatively, the slice thickness of the inversion module can be adapted according to the number of segments and slice thickness of the imaging module. Alternatively, the radio frequency energy of the inversion module can be adapted according to the SAR limitations of the imaging area. Furthermore, adiabatic pulses can be used in the inversion module for signal inversion to increase the robustness of the inversion.

[0102] Furthermore, after obtaining the parameters of the inversion module, the target inversion recovery scan sequence is obtained based on the inversion module and the imaging module. The target inversion recovery scan sequence is then applied to the target scanning area to obtain a magnetic resonance image.

[0103] Figure 10 This is a schematic diagram of a magnetic resonance image obtained using traditional methods. Wherein, Figure 10 These are magnetic resonance images of the same tissue acquired using FSE (FastSpin Echo Short) STIR (Short TI Inversion Recovery) sequences under different excitation and refocusing pulse configurations. Figure 10 It can be seen that the fat inhibition effect of the same tissue indicated by the arrow varies significantly under different configurations, with a large difference in fat tissue inhibition.

[0104] Figure 11 This is a schematic diagram of a magnetic resonance image in this embodiment. Figure 11 Based on the self-adaptive Short TI Inversion Recovery (STIR) sequence obtained in this embodiment, magnetic resonance images of the same tissue acquired under different excitation and refocusing pulse configurations are shown below. Figure 11 As shown, the fat inhibition effect did not differ significantly under different excitation pulse and re-recognition pulse configurations, and the uniformity was good.

[0105] In this embodiment, the pulse parameters in the inversion module of the magnetic resonance sequence are obtained based on the target scanning area and the imaging module in the magnetic resonance sequence. This results in good fat suppression when performing inversion recovery imaging based on the target inversion recovery scanning sequence, and it is applicable to various magnetic resonance scenarios and magnetic resonance emission systems, rather than being limited to a specific parameter or sequence. The target inversion recovery scanning sequence obtained based on the inversion recovery scanning sequence generation method can be widely applied to the whole body of the scanned object.

[0106] It should be understood that although the steps in the flowcharts of the above embodiments are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the above embodiments may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages in other steps. For example, steps 404 and 406 can be executed synchronously or asynchronously, or alternately.

[0107] Based on the same inventive concept, this application also provides a magnetic resonance imaging apparatus for implementing the magnetic resonance imaging method described above. The solution provided by this apparatus is similar to the implementation described in the above method; therefore, the specific limitations in one or more magnetic resonance imaging apparatus embodiments provided below can be found in the limitations of the magnetic resonance imaging method described above, and will not be repeated here.

[0108] In one embodiment, such as Figure 12 As shown, a magnetic resonance imaging device is provided, comprising: a sequence acquisition module, a position acquisition module, a parameter acquisition module, and a scanning module, wherein:

[0109] The sequence acquisition module is used to acquire the initial inversion recovery scan sequence, which includes the inversion module and the imaging acquisition module.

[0110] The location acquisition module is used to obtain the first gradient-coded location information of the set tissue of the target scanning area based on the imaging acquisition module;

[0111] The parameter acquisition module determines the gradient encoding parameters of the inversion module based on the first gradient encoding position information, and obtains the target inversion recovery scan sequence;

[0112] The scanning module is used to scan the target scanning area according to the target inversion recovery scanning sequence to obtain magnetic resonance images.

[0113] In one embodiment, the location acquisition module obtains the first gradient-coded location information of a set tissue at the target scanning site based on the imaging acquisition module, including: obtaining the first excitation region corresponding to the set tissue in the imaging acquisition module based on the excitation pulse and / or refocusing pulse in the imaging acquisition module, and using the first excitation region as the first gradient-coded location information.

[0114] Furthermore, in one embodiment, the parameter acquisition module determines the gradient encoding parameters of the inversion module based on the first gradient encoding position information by: obtaining the second gradient encoding position information of the set tissue corresponding to the inversion module based on the first gradient encoding position information; and determining the gradient encoding parameters of the inversion module based on the second gradient encoding position information.

[0115] Optionally, the parameter acquisition module obtains the second gradient encoding position information of the set tissue corresponding to the inversion module based on the first gradient encoding position information; and determines the gradient encoding parameters of the inversion module based on the second gradient encoding position information, including: obtaining the second excitation region of the set tissue in the inversion module based on the first gradient encoding position information to obtain the second gradient encoding position information; wherein the overlap range between the second excitation region and the first excitation region satisfies a preset condition; and determines the layer selection gradient position information of the inversion module based on the second gradient encoding position information.

[0116] In one embodiment, the parameter acquisition module execution method further includes: obtaining the gradient magnetic field strength of the inversion module based on the second gradient encoding position information; and obtaining the bandwidth of the adiabatic pulse contained in the inversion module based on the gradient magnetic field strength and the selected layer gradient position information.

[0117] Furthermore, the parameter acquisition module determines the selected layer gradient position information of the inversion module based on the second gradient encoding position information, including: determining the layer position of the inversion module through the second gradient encoding position information; determining the layer thickness information of the inversion module according to the layer position and the layer thickness selected by the imaging acquisition module; wherein, the layer thickness of the inversion module is greater than or equal to the layer thickness selected by the imaging acquisition module.

[0118] In one embodiment, the parameter acquisition module execution method further includes: obtaining the amplitude of the inversion pulse in the inversion module based on the radio frequency emission intensity of the radio frequency field corresponding to the target scanning part.

[0119] In one embodiment, the parameter acquisition module further includes: acquiring a threshold value of the specific absorption rate of the target scanning area to electromagnetic radiation; and obtaining the radio frequency energy of the inversion module based on the threshold value, so that when the inversion module is applied to the target scanning area, the specific absorption rate caused by the radio frequency energy is less than the threshold value of the specific absorption rate.

[0120] In one embodiment, the parameter acquisition module further includes: evaluating the uniformity of the radio frequency field corresponding to the target scanning area; and adjusting the gradient encoding parameters of the inversion module according to the evaluation result so that the change value of the flip angle of the inversion module in the radio frequency field is less than or equal to a specified change value.

[0121] Each module in the aforementioned magnetic resonance imaging device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in the processor of a computer device in hardware form or independent of it, or stored in the memory of a computer device in software form, so that the processor can call and execute the operations corresponding to each module.

[0122] Based on the same inventive concept, this application also provides a magnetic resonance imaging system for implementing the magnetic resonance imaging method described above. The solution provided by this system is similar to the implementation described in the above method; therefore, the specific limitations in one or more magnetic resonance imaging system embodiments provided below can be found in the limitations of the magnetic resonance imaging method described above, and will not be repeated here.

[0123] In one embodiment, a magnetic resonance imaging system is provided, comprising: a scanner and a controller. The controller is configured to perform the following steps: acquire an imaging acquisition module for a target scanning region, the imaging acquisition module including excitation pulses and convergence pulses; determine, based on the imaging acquisition module, first gradient encoding location information of a tissue at the target scanning region, wherein the tissue is defined as adipose tissue; set gradient encoding parameters for an inversion module based on the first gradient encoding location information to obtain a target inversion recovery scan sequence, the inversion module being applied before the imaging acquisition module; and control the scanner to apply the target inversion recovery scan sequence to the target scanning region to obtain a magnetic resonance image.

[0124] In one embodiment, the controller obtains the first gradient-coded position information of the set tissue at the target scanning site based on the imaging acquisition module, including: obtaining the first excitation region corresponding to the set tissue in the imaging acquisition module based on the excitation pulse and / or refocusing pulse in the imaging acquisition module, and using the first excitation region as the first gradient-coded position information.

[0125] Further, in one embodiment, the controller determines the gradient encoding parameters of the inversion module based on the first gradient encoding position information by: obtaining second gradient encoding position information of a designated tissue corresponding to the inversion module based on the first gradient encoding position information; and determining the gradient encoding parameters of the inversion module based on the second gradient encoding position information. Optionally, the controller obtains the second gradient encoding position information of a designated tissue corresponding to the inversion module based on the first gradient encoding position information; and determines the gradient encoding parameters of the inversion module based on the second gradient encoding position information by: obtaining a second excitation region of the designated tissue in the inversion module based on the first gradient encoding position information to obtain the second gradient encoding position information; wherein the overlap range between the second excitation region and the first excitation region satisfies a preset condition; and determining the layer selection gradient position information of the inversion module based on the second gradient encoding position information.

[0126] In one embodiment, the controller execution method further includes: obtaining the gradient magnetic field strength of the inversion module based on the second gradient encoded position information; and obtaining the bandwidth of the adiabatic pulse contained in the inversion module based on the gradient magnetic field strength and the selected layer gradient position information. Further, the controller determines the selected layer gradient position information of the inversion module based on the second gradient encoded position information, including: determining the layer position of the inversion module through the second gradient encoded position information; and determining the layer thickness information of the inversion module based on the layer position and the layer thickness selected by the imaging acquisition module; wherein the layer thickness of the inversion module is greater than or equal to the layer thickness selected by the imaging acquisition module.

[0127] In one embodiment, the controller execution method further includes: obtaining the amplitude of the inversion pulse in the inversion module based on the radio frequency emission intensity of the radio frequency field corresponding to the target scanning area.

[0128] In one embodiment, the controller execution method further includes: obtaining a threshold of the specific absorption rate of the target scanning area to electromagnetic radiation; and obtaining the radio frequency energy of the inversion module based on the threshold, so that when the inversion module is applied to the target scanning area, the specific absorption rate caused by the radio frequency energy is less than the threshold of the specific absorption rate.

[0129] In one embodiment, the controller execution method further includes: evaluating the uniformity of the radio frequency field corresponding to the target scanning area; and adjusting the gradient encoding parameters of the inversion module according to the evaluation result, so that the change value of the flip angle of the inversion module in the radio frequency field is less than or equal to a specified change value.

[0130] In one embodiment, a computer device is provided, which may be a server, and its internal structure diagram may be as follows: Figure 13As shown, this computer device includes a processor, memory, input / output (I / O) interfaces, and a communication interface. The processor, memory, and I / O interfaces are connected via a system bus, and the communication interface is also connected to the system bus via the I / O interfaces. The processor provides computational and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system, computer programs, and a database. The internal memory provides the environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The database stores data for each pulse in the magnetic resonance imaging sequence. The I / O interfaces are used for exchanging information between the processor and external devices. The communication interface is used for communication with external terminals via a network connection. When the computer program is executed by the processor, it implements a magnetic resonance imaging method.

[0131] Those skilled in the art will understand that Figure 13 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0132] In one embodiment, a computer device is also provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps in the above method embodiments.

[0133] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon that, when executed by a processor, implements the steps in the above method embodiments.

[0134] In one embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps in the above method embodiments.

[0135] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0136] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0137] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A magnetic resonance imaging method, characterized in that, The method includes: Acquire an initial inverted recovery scan sequence, the sequence including an inverting module and an imaging acquisition module; According to the imaging acquisition module, the first gradient encoding location information of the set tissue at the target scanning site is obtained; Based on the first gradient encoding position information, the gradient encoding parameters of the inversion module are determined to obtain the target inversion recovery scan sequence; The target scanning region is scanned according to the target inversion recovery scanning sequence to obtain a magnetic resonance image.

2. The method according to claim 1, characterized in that, The step of obtaining the first gradient-coded location information of the designated tissue at the target scanning site according to the imaging acquisition module includes: Based on the excitation pulse and / or refocusing pulse in the imaging acquisition module, a first excitation region corresponding to the set tissue in the imaging acquisition module is obtained, and the first excitation region is used as the first gradient encoding position information.

3. The method according to claim 2, characterized in that, The step of determining the gradient encoding parameters of the inversion module based on the first gradient encoding position information includes: Based on the first gradient encoding position information, the second gradient encoding position information of the set organization corresponding to the inversion module is obtained; The gradient encoding parameters of the inversion module are determined based on the second gradient encoding position information.

4. The method according to claim 3, characterized in that, The second gradient encoding position information of the set organization corresponding to the inversion module is obtained based on the first gradient encoding position information; Based on the second gradient encoding position information, the gradient encoding parameters of the inversion module are determined, including: The second excitation region of the set tissue in the inversion module is obtained according to the first gradient encoding position information, so as to obtain the second gradient encoding position information; wherein, the overlap range between the second excitation region and the first excitation region satisfies a preset condition; The layer selection gradient position information of the inversion module is determined based on the second gradient encoding position information.

5. The method according to claim 4, characterized in that, The method further includes: The gradient magnetic field strength of the inversion module is obtained based on the second gradient encoding position information; The bandwidth of the adiabatic pulse contained in the inversion module is obtained based on the gradient magnetic field strength and the selected layer gradient position information.

6. The method according to claim 4, characterized in that, The step of determining the layer selection gradient position information of the inversion module based on the second gradient encoding position information includes: The layer position of the inversion module is determined by the second gradient encoding position information; The layer thickness of the inversion module is determined based on the layer position and the layer thickness selected by the imaging acquisition module; wherein the layer thickness of the inversion module is greater than or equal to the layer thickness selected by the imaging acquisition module.

7. The method according to any one of claims 1 to 6, characterized in that, The method further includes: The amplitude of the inversion pulse in the inversion module is obtained based on the radio frequency emission intensity of the radio frequency field corresponding to the target scanning area.

8. The method according to any one of claims 1 to 6, characterized in that, The method further includes: Obtain the threshold value of the specific absorption rate of the target scanning area to electromagnetic radiation; The radio frequency energy of the inversion module is obtained based on the threshold, so that when the inversion module is applied to the target scanning area, the specific absorption rate caused by the radio frequency energy is less than the threshold of the specific absorption rate.

9. The method according to any one of claims 1 to 6, characterized in that, The method further includes: The uniformity of the radio frequency field corresponding to the target scanning area is evaluated; The gradient encoding parameters of the inversion module are adjusted according to the evaluation results so that the change value of the inversion module's flip angle in the radio frequency field is less than or equal to a specified change value.

10. A magnetic resonance imaging system, characterized in that, include: Scanner; The controller is configured to perform the following steps: An imaging acquisition module to be executed on the target scanning area is obtained, the imaging acquisition module including an excitation pulse and a convergence pulse; According to the imaging acquisition module, the first gradient encoding location information of the target scanning area is determined, wherein the set tissue is adipose tissue; Based on the first gradient encoding position information, gradient encoding parameters are set for the inversion module to obtain the target inversion recovery scan sequence, and the inversion module is applied in front of the imaging acquisition module; The scanner is controlled to apply the target inversion recovery scan sequence to the target scan area to obtain a magnetic resonance image.

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