Magnetic resonance scan control method, magnetic resonance imaging method, and storage medium

Abstract

The application discloses a magnetic resonance scanning control method, a magnetic resonance imaging method and a storage medium. The method comprises the following steps: acquiring a scanning sequence to be executed, the scanning sequence comprising an imaging sequence module and a navigation sequence module, parameters of the navigation sequence module being determined according to parameters of the imaging sequence module, and the navigation sequence module not comprising a phase encoding gradient; executing the navigation sequence module to obtain an echo signal of a target object excited thereby; determining motion information of the target object according to the echo signal; and controlling a collection timing sequence of the imaging sequence module based on the motion information to obtain a magnetic resonance signal of a region of interest of the target object. The application can correct motion offset of a magnetic resonance imaging signal of a target object according to motion information, so that the definition of a magnetic resonance image is improved, and artifacts in the magnetic resonance image are reduced or eliminated.

Description

Technical Field

[0001] This invention relates to the field of medical technology, and in particular to a magnetic resonance scanning control method, a magnetic resonance imaging method, and a storage medium. Background Technology

[0002] Magnetic resonance imaging (MRI) is a commonly used non-invasive clinical examination technique that provides high tissue contrast for the head and neck, abdomen, and joints throughout the body. It can effectively reflect the physiological structure of lesion areas, providing strong support for clinical diagnosis. MRI requires the sequential acquisition of one or more sets of K-space data, which are spatial frequency domain mappings of the MRI image data. Because the acquisition of the same set of K-space data spans a relatively long period, if the imaged area moves during data acquisition, the sequentially acquired K-space data will not physically match each other. This results in blurred images or even striped motion artifacts in the reconstructed images, affecting the physician's clinical judgment and posing a risk of misdiagnosis. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the defects in the prior art where the imaged part moves during data acquisition, resulting in blurred images or even motion artifacts. The present invention provides a magnetic resonance scanning control method, a magnetic resonance imaging method, and a storage medium.

[0004] The present invention solves the above-mentioned technical problems through the following technical solution:

[0005] Firstly, a magnetic resonance scanning control method is provided, comprising:

[0006] Obtain the scan sequence to be executed, the scan sequence includes an imaging sequence module and a navigation sequence module, the parameters of the navigation sequence module are determined according to the parameters of the imaging sequence module, and the navigation sequence module does not include phase-encoded gradients;

[0007] The navigation sequence module is executed to obtain the echo signal excited by the target object;

[0008] The motion information of the target object is determined based on the echo signal;

[0009] Based on the motion information, the acquisition timing of the imaging sequence module is controlled to obtain the magnetic resonance signal of the region of interest of the target object.

[0010] Optionally, the parameters of the navigation sequence module are determined in the following manner:

[0011] The layer selection gradient parameters and readout gradient parameters in the navigation sequence module are determined based on the layer selection gradient parameters in the imaging sequence module; or...

[0012] Based on the parameters of the imaging sequence module, the spatial distribution of the region of interest is determined; and based on the spatial distribution of the region of interest, the layer selection gradient parameters and readout gradient parameters in the navigation sequence module are determined.

[0013] Optionally, the navigation sequence module includes a first navigation sequence module and a second navigation sequence module that are sequentially consecutive, and the first navigation sequence module and the second navigation sequence module are located in the same repetition time.

[0014] Optionally, the first navigation sequence module and the second navigation sequence module can excite different slices, and the readout gradient directions in the first navigation sequence module and the second navigation sequence module are orthogonal.

[0015] Optionally, the imaging sequence is a 3D scanning sequence, wherein the slices excited by the first navigation sequence module and the slices excited by the second navigation sequence module are located on both sides of the region of interest.

[0016] Optionally, the magnetic resonance scanning control method further includes:

[0017] Identify regions of non-interest and determine their physical locations;

[0018] The interference signal components are determined based on the physical location of the non-interested region.

[0019] The echo signal is truncated based on the interference signal components.

[0020] Optionally, the magnetic resonance scanning control method further includes:

[0021] Identify regions of non-interest and determine their physical locations;

[0022] The application location of the navigation sequence module is determined based on the physical location of the region of non-interest, and the application of the navigation sequence module avoids the region of non-interest.

[0023] Optionally, determining the motion information of the target object based on the echo signal includes:

[0024] Based on the edge detection algorithm, motion features reflecting the target object are extracted from the echo signal;

[0025] The motion information is determined based on the motion characteristics.

[0026] Secondly, a magnetic resonance imaging method is provided, including:

[0027] Obtain the scan sequence to be executed, the scan sequence includes an imaging sequence module and a navigation sequence module, the parameters of the navigation sequence module are determined according to the parameters of the imaging sequence module, and the navigation sequence module does not include phase-encoded gradients;

[0028] The navigation sequence module is executed to obtain the echo signal excited by the target object;

[0029] The motion information of the target object is determined based on the echo signal;

[0030] The imaging sequence module is executed to obtain the magnetic resonance signal of the region of interest of the target object;

[0031] Based on the motion information, motion offset correction is performed on the magnetic resonance signal;

[0032] Image reconstruction is performed based on the corrected magnetic resonance signal.

[0033] Thirdly, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the method described in any of the preceding claims.

[0034] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0035] The positive and progressive effects of this invention are as follows: This invention adds a navigation sequence module that does not interfere with the imaging sequence module to the magnetic resonance scanning sequence, obtains the echo signal of the target object obtained by executing the navigation sequence module, determines the motion information of the target object based on the echo signal, and performs motion offset correction on the magnetic resonance imaging signal of the target object based on the motion information, so as to improve the clarity of the magnetic resonance image and reduce or eliminate artifacts in the magnetic resonance image. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the structure of a magnetic resonance imaging system shown in an exemplary embodiment of the present invention;

[0037] Figure 2 A flowchart of a magnetic resonance scanning control method provided as an exemplary embodiment of the present invention;

[0038] Figure 3a A schematic diagram of a scanning sequence used in a magnetic resonance scanning control method provided as an exemplary embodiment of the present invention;

[0039] Figure 3b A schematic diagram of the excitation layer selected in a magnetic resonance scanning control method provided for an exemplary embodiment of the present invention;

[0040] Figure 3cA schematic diagram of the excitation layer selected for another magnetic resonance scanning control method provided as an exemplary embodiment of the present invention;

[0041] Figure 3d A schematic diagram of the excitation layer selected for another magnetic resonance scanning control method provided as an exemplary embodiment of the present invention;

[0042] Figure 3e A schematic diagram illustrating the signal readout direction of a magnetic resonance scanning control method provided as an exemplary embodiment of the present invention;

[0043] Figure 3f A schematic diagram of an echo signal obtained by a magnetic resonance scanning control method according to an exemplary embodiment of the present invention;

[0044] Figure 3g A schematic diagram of the echo signal obtained by another magnetic resonance scanning control method provided as an exemplary embodiment of the present invention;

[0045] Figure 3h A flowchart illustrating the extraction of motion features in a magnetic resonance scanning control method provided as an exemplary embodiment of the present invention;

[0046] Figure 4 A flowchart of a magnetic resonance imaging method provided as an exemplary embodiment of the present invention;

[0047] Figure 5 This is a schematic diagram of the structure of an electronic device shown in an example embodiment of the present invention. Detailed Implementation

[0048] The present invention will be further illustrated by way of embodiments below, but the present invention is not limited to the scope of the embodiments described herein.

[0049] Figure 1 This is a schematic diagram of the structure of a magnetic resonance imaging (MRI) system according to an exemplary embodiment of the present invention, as shown below. Figure 1 As shown, the MRI system includes an MRI device 110, a display and operation device 120, and a data processor 130. The MRI device 110 includes a magnet 111, a gradient coil 112, and a radio frequency coil 113.

[0050] Magnet 111 generates a static magnetic field to adjust the direction of the magnetic dipole moment of the atomic nuclei in a target object (which may be a person or animal, or a part of a person or animal) to a constant direction.

[0051] The gradient coil 112 includes an X coil, a Y coil, and a Z coil for generating magnetic field gradients along the X-axis, Y-axis, and Z-axis directions that intersect each other at right angles. The gradient coil 112 can provide spatial positioning information of the target object by inducing different resonant frequencies depending on the region of the target object. Specifically, a gradient magnetic field in one direction is used as the slice selection gradient to determine the scanning slice, and then gradient magnetic fields in the other two directions are used to determine the coordinate position within the slice. By different combinations of the three gradient magnetic fields, arbitrary slice tomographic imaging can be achieved.

[0052] The radio frequency (RF) coil 113 can send RF pulse signals to a target object and acquire MR (magnetic resonance) signals emitted from the target object. Specifically, the RF coil 113 generates RF pulse signals corresponding to the type of atomic nucleus and applies these RF pulse signals to the target object, causing the atomic nuclei of the target object to transition from a low-energy state to a high-energy state. When the RF pulse signal generated by the RF coil 113 disappears, the atomic nuclei transition from a high-energy state to a low-energy state, thereby emitting electromagnetic waves (MR signals) with Larmor frequencies. In other words, when the RF pulse signal is stopped being applied to the target object, the energy level of the atomic nuclei of the target object changes from a high-energy level to a low-energy level, thus emitting electromagnetic waves with Larmor frequencies, at which point the RF coil 113 can acquire MR data.

[0053] The data processor 130 can process the MR signal acquired by the radio frequency coil 113 to reconstruct an image. The display device 120 can display the image reconstructed by the data processor 130.

[0054] During magnetic resonance imaging (MRI), the acquired magnetic resonance signals need to be filled into the K-space, which means filling the original acquired MR signals into the spatial frequency domain. For image reconstruction, an inverse Fourier transform is performed on the K-space to obtain the reconstructed image.

[0055] Because the target object moves during data acquisition (muscle contraction, respiratory movements, etc.), the same set of K-space data collected in multiple sessions will not be able to match each other in physical space. As a result, the reconstructed image will be blurry, or even show striped motion artifacts, which will affect the doctor's clinical judgment and pose a risk of misdiagnosis.

[0056] Based on this, embodiments of the present invention provide a magnetic resonance scanning control method. By adding a navigation sequence module that does not interfere with the imaging sequence module to the magnetic resonance scanning sequence, the motion state of the target object during the magnetic resonance scanning process is detected based on the navigation sequence module. The obtained motion information of the target object can be used to perform motion offset correction on the magnetic resonance signal of the target object, so as to improve the clarity of the magnetic resonance image and reduce or eliminate artifacts in the magnetic resonance image.

[0057] Figure 2A flowchart of a motion detection method for magnetic resonance imaging provided as an exemplary embodiment of the present invention is included, the motion detection method comprising the following steps:

[0058] Step 201: Obtain the scan sequence to be executed.

[0059] The scanning sequence includes an imaging sequence module and a navigation sequence module for motion detection, which do not interfere with each other. The parameters of the navigation sequence module are determined based on the parameters of the imaging sequence module, and the navigation sequence module does not include phase-encoded gradients. Specifically, the scanning sequence comprises the settings and temporal arrangement of various parameters, such as radio frequency pulses, gradient pulses, and signal acquisition times. The parameters of the scanning sequence include the bandwidth (frequency range), amplitude (intensity), application time, and duration of the radio frequency pulses. The parameters may also include the gradient field application direction, gradient field strength, application time, and duration. In this embodiment, the scanning sequence to be executed can be obtained by setting the radio frequency pulse parameters and the gradient pulse parameters.

[0060] Figure 3a This is a schematic diagram of a scanning sequence provided as an exemplary embodiment of the present invention. The diagram illustrates a set of navigation sequence modules and a set of imaging sequence modules within a repetition time (TR). See also... Figure 3a The navigation sequence module includes an excitation pulse, a layer-selection gradient pulse, and a readout gradient pulse. The excitation pulse and the layer-selection gradient pulse are applied simultaneously to the target object, without applying a phase-encoded gradient, to cause the excited layer of the target object to emit an echo signal (electromagnetic wave signal). The readout gradient pulse is applied within a short echo time to read the echo signal of the target object along the signal readout direction. This echo signal is a one-dimensional signal of the excited layer along the signal readout direction, capable of characterizing the motion information of the target object.

[0061] It should be noted that the number of navigation sequence modules in each TR can be set according to the actual situation, and is not limited to... Figure 3a The example shown is a single module, but multiple modules can be configured. When multiple navigation sequence modules are configured, each module can excite one or more different excitation layers, and then use one or more mutually orthogonal signal readout directions to acquire the echo signals from these excitation layers.

[0062] In one embodiment, the imaging process includes multiple repetition times (TRs), and a navigation sequence module can be added to all or some of the TRs. The navigation sequence module is set before the imaging sequence module. For repetition times (TRs) in which the navigation sequence module is added, the navigation sequence module is executed first to determine the motion information of the target object before the imaging sequence module is executed.

[0063] There can be a time interval between the navigation sequence module and the imaging sequence module. That is, after the navigation sequence module is executed, the imaging sequence module is executed after a time interval to ensure that the navigation sequence module and the imaging sequence module do not interfere with each other. The time interval can be set according to the actual situation.

[0064] The term "no interference" means that the echo signal acquired by the navigation sequence module is not mixed with the magnetic resonance signal and other irrelevant signals acquired by the imaging sequence module that would affect motion detection, and the magnetic resonance signal acquired by the imaging sequence module is not mixed with the echo signal acquired by the navigation sequence module that would interfere with the accuracy and stability of imaging.

[0065] In one embodiment, different imaging sequence modules are matched with different navigation sequence modules. Since magnetic resonance signals acquired based on different imaging sequence modules have different anti-interference capabilities, different navigation sequence modules are matched for different imaging sequence modules.

[0066] In one implementation, the layer selection gradient parameters and readout gradient parameters in the navigation sequence module are determined based on the layer selection gradient parameters in the imaging sequence module.

[0067] For example, the gradient echo sequence module (imaging sequence module) has high requirements for the steady state of signal evolution, so the density of the inserted navigation sequence modules cannot be too high, and the flip angle of the excitation pulse used in the navigation sequence module cannot be too large. The value range of the flip angle of the excitation pulse can be [4°, 15°], preferably 5°. In contrast, the insertion interval of the navigation sequence module in the fast spin echo sequence module (imaging sequence module) and the planar echo sequence module (imaging sequence module) only needs one repetition time or even shorter. The flip angle of the excitation pulse of the navigation sequence module added in the scanning sequence module that includes the fast spin echo sequence module and the planar echo sequence module can be set to a larger value, for example, greater than 5°.

[0068] Different navigation sequence modules can be used for both two-dimensional and three-dimensional imaging sequence modules, i.e., different layer selection gradient pulses and readout gradient pulses. In the two-dimensional imaging sequence module, the layer selection direction of the excitation layer and the signal readout direction of the navigation sequence module are adjusted according to the excitation layer of the imaging. In the three-dimensional sequence module, the layer selection direction of the excitation layer of the navigation sequence module is determined according to the spatial distribution of the target object, and the signal readout direction is determined accordingly.

[0069] In one embodiment, if the plane excited by the navigation sequence module does not overlap with the plane excited by the imaging sequence module, then the plane excited by the navigation sequence module needs to be specially designed to avoid signals from the plane excited by the imaging sequence module and other interfering areas. For example, if the excitation pulse and convergence pulse of the imaging sequence module both use pulses with large flip angles, and the navigation sequence module chooses to excite a plane that overlaps with the plane excited by the imaging sequence module, then the echo signal acquired by the navigation sequence module may contain residual signals from the previous repetition time (TR) that were not recovered after excitation by the imaging sequence module. Since residual signals are difficult to reach a steady state, there will be significant differences between the echo signals acquired by the navigation sequence module each time when testing stationary parts, leading to misjudgment of the motion state of the part. For example, when detecting head motion, if the excitation plane excited by the navigation sequence module is in the sagittal plane and the signal readout direction is in the anterior-posterior direction, then the acquired echo signal will contain motion information from the torso below the head, making it impossible to judge head motion independently. The excitation plane excited by the navigation sequence module does not overlap with the excitation plane excited by the imaging sequence module, which can effectively avoid signal interference.

[0070] In one embodiment, different target objects are matched with different navigation sequence modules. Different target objects are suited to different excitation levels for motion information detection; therefore, different target objects are matched with different navigation sequence modules.

[0071] The layer selection gradient pulse and readout gradient pulse of the navigation sequence module can also be adjusted according to the location of the region of interest of the target object. That is, the layer selection direction of the excitation pulse and the signal readout direction are adjusted to avoid signal interference from areas outside the region of interest of imaging as much as possible.

[0072] In one implementation, the spatial distribution of the region of interest is determined based on the parameters of the imaging sequence module, and the layer selection gradient parameters and readout gradient parameters in the navigation sequence module are determined based on the spatial distribution of the region of interest.

[0073] In one embodiment, the excitation pulse of the navigation sequence module is applied to the region of interest of the target object. It is understood that the excitation pulse of the imaging sequence module is also applied to the region of interest of the target object. In order to avoid mutual interference between the imaging sequence module and the navigation sequence module, the flip angle of the excitation pulse of the navigation sequence module is set to be relatively small, and its value range is [4°, 15°]. Preferably, the flip angle of the excitation pulse of the navigation sequence module is 5°.

[0074] In one embodiment, the excitation pulse of the navigation sequence module is applied to the non-interest region of the target object, that is, the adjacent layer outside the target object's interest region, see [link to relevant documentation]. Figure 3bThe adjacent layer outside the region of interest is used as the motion detection layer, which is also the excitation layer of the excitation pulse of the navigation sequence module. At this time, the flip angle of the excitation pulse of the navigation sequence module can be increased to ensure the stability of the echo signal. Its value range is [60°, 180°]. Preferably, the flip angle of the excitation pulse of the navigation sequence module is 90° or 180°.

[0075] Whether the excitation pulse of the navigation sequence module is applied to the region of interest (ROI) or a non-ROI depends on the target object. For example, when the target object is a part of the neck, chest, or abdomen where local motion states differ greatly, the excitation level of the navigation sequence module's excitation pulse is selected within the ROI. When the target object is a part of the head or legs where only approximate rigid body motion is possible, the excitation level of the navigation sequence module's excitation pulse can be selected not only within the imaging ROI but also on an adjacent level outside the ROI. In this case, the signal readout direction can be any direction within the level.

[0076] In one embodiment, the scanning sequence includes at least two sets of navigation sequence modules, each set of navigation sequence modules includes a layer selection gradient pulse, which corresponds to a readout gradient pulse, and the readout directions of the readout gradient pulses of each set of navigation sequence modules are orthogonal to each other.

[0077] Taking a scan sequence that includes two sets of navigation sequence modules as an example, the two sets of navigation sequence modules are a first navigation sequence module and a second navigation sequence module that are sequentially consecutive, and the first navigation sequence module and the second navigation sequence module are located in the same repetition time.

[0078] Furthermore, the first navigation sequence module and the second navigation sequence module excite different slices respectively, and the readout gradient directions in the first navigation sequence module and the second navigation sequence module are orthogonal.

[0079] When the imaging sequence module is a two-dimensional imaging sequence module, the excitation layer of the navigation sequence module is preferentially arranged in the transverse section. The position of the excitation layer is generally selected in several layers in the middle of the region of interest. In order to obtain motion information in two directions, two layers are generally selected for excitation, and the signal readout directions of each layer are orthogonal to each other.

[0080] Furthermore, certain scanning sequence modules require special processing based on the location of the target object. For example, when imaging the head, the excitation plane of the navigation sequence module should avoid areas with involuntary physiological movements, such as the mouth, that do not affect imaging. See [link to documentation]. Figure 3c For example, when imaging the shoulder joint, the excitation plane of the navigation sequence module should avoid cutting into the major artery as much as possible to prevent blood flow from interfering with motion detection. At the same time, the signal readout direction should also avoid the direction of the excitation plane of the imaging sequence module as much as possible.

[0081] In one embodiment, the method prior to step 202 further includes: identifying a region of non-interest of the target object and determining the physical location of the region of non-interest; determining the application location of the navigation sequence module based on the physical location of the region of non-interest; and applying the navigation sequence module to avoid the region of non-interest.

[0082] Table 1 illustrates, for example, the layer readout direction of the navigation sequence module when the imaging sequence module is a two-dimensional imaging sequence module.

[0083]

[0084] When the imaging sequence module is a three-dimensional imaging sequence module, layer selection is not required. Generally, the excitation plane of the navigation sequence module (the motion detection navigation excitation plane in the figure) is fixed at the transverse section. That is, the layers excited by the first navigation sequence module and the layers excited by the second navigation sequence module are located on either side of the region of interest. See [reference needed]. Figure 3d The two layers are fixed at the center of the region of interest (the center of the imaging volume block) and are symmetrically positioned on both sides along the head-to-toe direction, with a certain distance between them. The signal readout directions (the readout directions of the first layer and the second layer in the figure) are fixed as front-back and left-right directions, respectively.

[0085] When the target object is a specific part, such as a joint, the excitation plane direction of the navigation sequence module can be selected in the oblique transverse plane, oblique coronal plane, or oblique sagittal plane, and the signal readout directions in different excitation planes can be mutually orthogonal.

[0086] In one embodiment, the readout gradient pulses included in the navigation sequence module and the readout gradient pulses included in the imaging sequence module are at an angle. To resolve the signal overlap problem, when imaging a portion of the target object, the signal readout direction of the navigation sequence module needs to be rotated by a certain angle, see [link to relevant documentation]. Figure 3e This ensures that the echo signals inside and outside the region of interest acquired by the navigation sequence module do not overlap along the rotated signal readout direction.

[0087] In this embodiment of the invention, navigation sequence modules are meticulously designed for different types of imaging sequence modules, ensuring the effectiveness and stability of the echo signals acquired by the navigation sequence modules. Different detection strategies are adopted for different parts of the target object, improving the accuracy of motion state detection of the target object.

[0088] Step 202: Execute the navigation sequence module to obtain the echo signal excited by the target object.

[0089] The echo signal of the target object can be acquired by executing the readout gradient pulse of the navigation sequence module. The magnetic resonance scanning control method also includes: identifying the non-interest region of the target object and determining the physical location of the non-interest region; determining the interference signal component in the echo component excited by the target object based on the physical location of the non-interest region; truncating the echo signal based on the interference signal component; and subsequently reconstructing the image based on the truncated echo signal (the final echo signal).

[0090] In one embodiment, the signal from the non-interest region of imaging can interfere with the determination of the motion state of the region of interest, so the echo signal acquired by the navigation sequence module needs to be preprocessed.

[0091] In one embodiment, step 202 specifically includes: acquiring the initial echo signal emitted by the target object when the navigation sequence module is executed; determining the first distribution information of the non-interest region of the target object along the signal readout direction in the initial echo signal according to the direction of the excitation layer of the imaging sequence module and the direction of the excitation layer of the layer selection gradient pulse; and removing the echo signal of the non-interest region from the initial echo signal according to the first distribution information to obtain the final echo signal.

[0092] Since regions of non-interest are typically located at the edges, see Figure 3f It is assumed that the first peak of the signal, counting from the two extremes towards the middle, originates from the region of non-interest. Finally, when calculating motion information, a mask is used to remove the signal distribution from the region of non-interest.

[0093] In one embodiment, step 202 specifically includes: acquiring the initial echo signal emitted by the target object when the navigation sequence module is executed; determining the second distribution information of the region of interest of the target object along the signal readout direction in the initial echo signal based on the direction of the excitation layer of the imaging sequence module and the direction of the excitation layer of the layer selection gradient pulse; filtering the echo signal of the region of interest from the initial echo signal based on the second distribution information to obtain the final echo signal.

[0094] The difference between the first distribution information and the second distribution information lies in the different excitation level and readout direction of the navigation sequence module.

[0095] In one embodiment, the method prior to step 202 further includes: identifying a region of non-interest of interest (ROI) of the target object and determining the physical location of the ROI; determining the application location of the navigation sequence module based on the physical location of the ROI; and applying the navigation sequence module to avoid the ROI. The echo signal excited by the target object obtained in this manner does not require truncation.

[0096] In one embodiment, the physical location of the non-interest area can also be obtained through external cameras, sensors, etc., and determined through feature extraction or deep learning methods.

[0097] Step 203: Determine the motion information of the target object based on the echo signal.

[0098] The motion information includes the motion offset of the target object.

[0099] Step 204: Based on motion information, control the acquisition timing of the imaging sequence module to obtain the magnetic resonance signal of the region of interest of the target object.

[0100] Since the navigation sequence module is always activated at a fixed position, and it is assumed that a change in the activation position will cause a change in the acquired echo signal, the motion offset of the target object can be roughly estimated by comparing the difference with the reference signal. The reference signal is the echo signal of the target object obtained by executing the first set of navigation sequence modules; or the reference signal is the echo signal of the target object obtained by executing the previous set of navigation sequence modules.

[0101] In one embodiment, considering pulse stability issues, all echo signals acquired by the navigation sequence module may not be completely reliable. Therefore, it is necessary to extract useful features reflecting the motion state of the target object from the echo signals. The steps for determining the motion information of the target object based on the echo signals specifically include: extracting motion features reflecting the target object from the echo signals based on an edge detection algorithm, and determining the motion information based on these motion features. See also... Figure 3g The motion characteristics are the leftmost rising edge and the rightmost falling edge of the one-dimensional echo signal, and the features of the points located on the edge half-wave height are selected.

[0102] For details on the implementation process, please refer to [link / document / etc.]. Figure 3g and Figure 3h The echo signal is subjected to a Gaussian filter, and then a differential transform is performed on the Gaussian-filtered echo signal. Points where the differential values ​​change from positive to negative from left to right are marked as peaks. From these peaks, peaks approximately 20% of the first signal's maximum value are found. Half-peaks are located to the left and right of the left and right peaks, respectively, using half the amplitude value of the corresponding peak. A certain range on either side of these half-peaks is defined as the feature region for motion detection, from which motion features are extracted. This process allows the acquisition of key information characterizing the motion state of the target object, exhibiting robustness to noise and system state changes, thus improving the accuracy and stability of motion detection.

[0103] In this embodiment of the invention, a navigation sequence module that does not interfere with the imaging sequence module is added to the magnetic resonance scanning sequence. The echo signal of the target object to the navigation sequence module is obtained, and the motion information of the target object is determined based on the echo signal. This motion information is used to perform motion offset correction on the magnetic resonance signal of the target object to the navigation sequence module, so as to improve the clarity of the magnetic resonance image and reduce or eliminate artifacts in the magnetic resonance image.

[0104] Figure 4 A flowchart of a magnetic resonance imaging method provided as an exemplary embodiment of the present invention is included, the magnetic resonance imaging method comprising the following steps:

[0105] Step 401: Obtain the scan sequence to be executed. The scan sequence includes an imaging sequence module and a navigation sequence module. The parameters of the navigation sequence module are determined based on the parameters of the imaging sequence module, and the navigation sequence module does not include phase-encoded gradients.

[0106] Step 402: Execute the navigation sequence module to obtain the echo signal excited by the target object.

[0107] Step 403: Determine the motion information of the target object based on the echo signal. The specific implementation of steps 401 to 403 is similar to that of steps 201 to 203, and will not be described again here.

[0108] Step 404: Execute the imaging sequence module to obtain the magnetic resonance signal of the region of interest of the target object.

[0109] Step 405: Based on the motion information, perform motion offset correction on the magnetic resonance signal of the target object obtained by the imaging sequence module.

[0110] The following describes a method for motion offset correction, applicable to situations where the target object undergoes rigid motion.

[0111] The resolution of the readout signal from the navigation sequence module is defined as the minimum identifiable offset.

[0112] Step 1: Perform an inverse Fourier transform on the one-dimensional signal acquired by the navigation sequence module;

[0113] Step 2: Using the smallest identifiable offset as the unit, shift the inverse-transformed signal to both sides along the readout direction. Enumerate and shift by one to several units sequentially, calculating the F-norm of the difference between the shifted signal and the transformed reference signal (as shown below).

[0114]

[0115] The translation amount corresponding to the smallest F-norm is used as the motion offset estimate of the target object in the readout direction of the navigation sequence module.

[0116] Step 3: Collect motion information in one or more readout directions according to the navigation sequence modules in Step 1 and Step 2. Finally, synthesize the estimated motion offsets in each readout direction into vectors to obtain the motion offset and direction of the target object.

[0117] It is worth noting that the motion offset and direction have time attributes, that is, they correspond to the time of each navigation sequence module.

[0118] Based on motion information, motion offset correction is performed on the magnetic resonance signal of the target object acquired by the imaging sequence module.

[0119] The following presents another implementation method for motion offset correction, specifically for general fast spin echo imaging sequence modules and gradient echo imaging sequence modules:

[0120] The estimated motion offset is plotted as a curve over time. The position of the signal acquired by the imaging sequence module corresponding to the navigation sequence module in the K-space is recorded. The motion offset corresponding to the signal in the central region of the K-space is used as a reference. If the motion offset corresponding to the signal in other regions of the K-space differs from the reference by more than a certain threshold, the system re-acquires the K-space.

[0121] The following presents another method for motion offset correction, specifically for a general planar echo imaging sequence module:

[0122] Each layer of the reconstructed image in the planar echo imaging sequence module corresponds to a motion offset in the plane (not considering motion in the interlayer direction). Therefore, each pixel of the image is translated according to this motion offset.

[0123] Step 406: Reconstruct the image based on the corrected magnetic resonance signal.

[0124] In this embodiment of the invention, after motion offset correction of the magnetic resonance signal of the target object, image reconstruction is then performed, which can effectively eliminate or reduce artifacts in the magnetic resonance image and obtain a magnetic resonance image with higher clarity.

[0125] Figure 5 This is a schematic diagram of the structure of an electronic device according to an example embodiment of the present invention, showing a block diagram of an exemplary electronic device 50 suitable for implementing embodiments of the present invention. Figure 5 The electronic device 50 shown is merely an example and should not impose any limitation on the functionality and scope of use of the embodiments of the present invention.

[0126] like Figure 5As shown, the electronic device 50 can be manifested in the form of a general-purpose computing device, such as a server device. The components of the electronic device 50 may include, but are not limited to: at least one processor 51, at least one memory 52, and a bus 53 connecting different system components (including memory 52 and processor 51).

[0127] Bus 53 includes a data bus, an address bus, and a control bus.

[0128] The memory 52 may include volatile memory, such as random access memory (RAM) 521 and / or cache memory 522, and may further include read-only memory (ROM) 523.

[0129] The memory 52 may also include a program tool 525 (or utility) having a set (at least one) program module 524, such program module 524 including but not limited to: an operating system, one or more application programs, other program modules, and program data, each or some combination of these examples may include an implementation of a network environment.

[0130] The processor 51 performs various functional applications and data processing, such as the methods provided in any of the above embodiments, by running computer programs stored in the memory 52.

[0131] Electronic device 50 can also communicate with one or more external devices 54 (e.g., keyboard, pointing device, etc.). This communication can be performed via input / output (I / O) interface 55. Furthermore, the model-generated electronic device 50 can also communicate with one or more networks (e.g., local area network (LAN), wide area network (WAN), and / or public networks, such as the Internet) via network adapter 56. As shown, network adapter 56 communicates with other modules of the model-generated electronic device 50 via bus 53. It should be understood that, although not shown in the figure, other hardware and / or software modules can be used in conjunction with the model-generated electronic device 50, including but not limited to: microcode, device drivers, redundant processors, external disk drive arrays, RAID (disk array) systems, tape drives, and data backup storage systems.

[0132] It should be noted that although several units / modules or sub-units / modules of the electronic device have been mentioned in the detailed description above, this division is merely exemplary and not mandatory. In fact, according to embodiments of the present invention, the features and functions of two or more units / modules described above can be embodied in one unit / module. Conversely, the features and functions of one unit / module described above can be further divided and embodied by multiple units / modules.

[0133] This invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method provided in any of the above embodiments.

[0134] The readable storage medium may be more specifically adopted, including but not limited to: portable disk, hard disk, random access memory, read-only memory, erasable programmable read-only memory, optical storage device, magnetic storage device, or any suitable combination thereof.

[0135] In a possible implementation, the present invention can also be implemented as a program product comprising program code, wherein when the program product is run on a terminal device, the program code is used to cause the terminal device to execute the method implementing any of the above embodiments.

[0136] The program code for executing the present invention can be written in any combination of one or more programming languages. The program code can be executed entirely on the user device, partially on the user device, as a standalone software package, partially on the user device and partially on a remote device, or entirely on a remote device.

[0137] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A magnetic resonance scanning control method, characterized in that, include: Obtain the scan sequence to be executed, the scan sequence includes an imaging sequence module and a navigation sequence module, the parameters of the navigation sequence module are determined according to the parameters of the imaging sequence module, and the navigation sequence module does not include phase-encoded gradients; The navigation sequence module is executed to obtain the echo signal emitted by the target object; The motion information of the target object is determined based on the echo signal; wherein the motion information includes the motion offset of the target object; Based on the motion information, the acquisition timing of the imaging sequence module is controlled to perform motion offset correction on the magnetic resonance signal of the region of interest of the target object acquired by the imaging sequence module. The motion offset correction includes: The position of the magnetic resonance signal acquired by the imaging sequence module in K-space is recorded according to the motion offset. Using the motion offset corresponding to the signal in the central region of K-space as a reference, if the motion offset corresponding to the signal in other regions of K-space differs from the reference by more than a certain threshold, then K-space is re-acquired; or... Each pixel of the reconstructed image at each layer is translated by a motion offset.

2. The magnetic resonance scanning control method according to claim 1, characterized in that, The parameters of the navigation sequence module are determined in the following way: The layer selection gradient parameters and readout gradient parameters in the navigation sequence module are determined based on the layer selection gradient parameters in the imaging sequence module; or... Based on the parameters of the imaging sequence module, the spatial distribution of the region of interest is determined; and based on the spatial distribution of the region of interest, the layer selection gradient parameters and readout gradient parameters in the navigation sequence module are determined.

3. The magnetic resonance scanning control method according to claim 1 or 2, characterized in that, The navigation sequence module includes a first navigation sequence module and a second navigation sequence module that are sequentially continuous, and the first navigation sequence module and the second navigation sequence module are located in the same repetition time.

4. The magnetic resonance scanning control method according to claim 3, characterized in that, The first navigation sequence module and the second navigation sequence module excite different slices, and the readout gradient directions in the first navigation sequence module and the second navigation sequence module are orthogonal.

5. The magnetic resonance scanning control method according to claim 4, characterized in that, The imaging sequence module is a 3D scanning sequence, and the slices excited by the first navigation sequence module and the slices excited by the second navigation sequence module are located on both sides of the region of interest.

6. The magnetic resonance scanning control method according to claim 3, characterized in that, The magnetic resonance scanning control method further includes: Identify regions of non-interest and determine their physical locations; The interference signal components are determined based on the physical location of the non-interested region. The echo signal is truncated based on the interference signal components.

7. The magnetic resonance scanning control method according to claim 1 or 2, characterized in that, The magnetic resonance scanning control method further includes: Identify regions of non-interest and determine their physical locations; The application location of the navigation sequence module is determined based on the physical location of the region of non-interest, and the application of the navigation sequence module avoids the region of non-interest.

8. The magnetic resonance scanning control method according to claim 1, characterized in that, Determining the motion information of the target object based on the echo signal includes: Based on the edge detection algorithm, motion features reflecting the target object are extracted from the echo signal; The motion information is determined based on the motion characteristics.

9. A magnetic resonance imaging method, characterized in that, include: Obtain the scan sequence to be executed, the scan sequence includes an imaging sequence module and a navigation sequence module, the parameters of the navigation sequence module are determined according to the parameters of the imaging sequence module, and the navigation sequence module does not include phase-encoded gradients; The navigation sequence module is executed to obtain the echo signal excited by the target object; The motion information of the target object is determined based on the echo signal; wherein the motion information includes the motion offset of the target object; The imaging sequence module is executed to obtain the magnetic resonance signal of the region of interest of the target object; Based on the motion information, motion offset correction is performed on the magnetic resonance signal of the target object acquired by the imaging sequence module. The motion offset correction includes: The position of the magnetic resonance signal acquired by the imaging sequence module in K-space is recorded according to the motion offset. Using the motion offset corresponding to the signal in the central region of K-space as a reference, if the motion offset corresponding to the signal in other regions of K-space differs from the reference by more than a certain threshold, then K-space is re-acquired; or... Each pixel of the reconstructed image at each layer is translated by a motion offset; Image reconstruction is performed based on the corrected magnetic resonance signal.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the method according to any one of claims 1 to 9.

Images