Magnetic resonance imaging method and adaptive magnetic resonance imaging method

Abstract

The invention relates to a magnetic resonance imaging method and an adaptive magnetic resonance imaging method. The method comprises the following steps: respectively acquiring effective coverage ranges of a plurality of coil units in a magnetic resonance imaging range; obtaining a modulation factor corresponding to each coil unit according to the effective coverage range and the receiving sensitivity of the coil unit; and performing channel merging reconstruction on the magnetic resonance signals received by the plurality of coil units according to the modulation factor to obtain a magnetic resonance image. By adopting the method, the effects of high signal-to-noise ratio and low peripheral artifacts can be achieved during magnetic resonance imaging.

Description

Magnetic resonance imaging methods and adaptive magnetic resonance imaging methods Technical Field

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

[0002] In magnetic resonance imaging (MRI), due to the limited range of the homogeneous region of the main magnetic field and the linear region of the gradient field, when the imaging range is large, in addition to image distortion, peripheral artifacts, such as feather artifacts, sometimes superimposed on the image. These artifacts are difficult to eliminate, and their occurrence is related to whether a coil unit is selected that extends too far beyond the imaging range: when the imaging range of the selected coil unit is contained within the image field of view, the coil unit contributes significantly to the signal-to-noise ratio (SNR). However, when the imaging range of the selected coil unit extends too far beyond the image field of view, the coil unit not only contributes limitedly to the SNR but also easily introduces the aforementioned peripheral artifacts. This is because the image field of view is generally located at the center of the magnet, and coil units extending beyond the imaging range are likely to deviate from the magnet center, entering the non-ideal regions of the main magnetic field and gradient field, leading to the introduction of artifacts into the received signal.

[0003] To reduce peripheral artifacts, related technologies determine whether to select a coil unit based on the relationship between the coil unit and the image imaging range. Under this mechanism, if a coil unit might introduce peripheral artifacts, it is not selected to avoid artifact introduction; if a coil unit has no possibility of introducing peripheral artifacts, it is selected to achieve imaging. However, while this setting eliminates peripheral artifacts to some extent, it introduces a low signal-to-noise ratio problem.

[0004] There is currently no effective solution to the problem that magnetic resonance imaging cannot simultaneously achieve a high signal-to-noise ratio and low peripheral artifacts. Summary of the Invention

[0005] Therefore, it is necessary to provide a magnetic resonance imaging method and an adaptive magnetic resonance imaging method that can solve the problem of not being able to simultaneously achieve high signal-to-noise ratio and low peripheral artifacts in magnetic resonance imaging.

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

[0007] The effective coverage of multiple coil units within the magnetic resonance imaging range is obtained separately;

[0008] Based on the effective coverage area and the receiving sensitivity of the coil unit, the modulation factor corresponding to each coil unit is obtained;

[0009] Based on the modulation factor, the magnetic resonance signals received by multiple coil units are channel-merged and reconstructed to obtain a magnetic resonance image.

[0010] In some of these embodiments, the effective coverage area of ​​multiple coil units within the magnetic resonance imaging range is obtained, including:

[0011] The scanning length of each coil unit in a specified axis and the imaging length in the specified axis during magnetic resonance imaging are obtained.

[0012] The effective coverage area is obtained based on the overlap length between the scan length and the imaging length.

[0013] In some of these embodiments, the effective coverage area of ​​multiple coil units within the magnetic resonance imaging range is obtained, including:

[0014] By combining the multiple scan lengths along multiple specified axes during the scanning of the coil unit, the scanning area of ​​the coil unit is obtained;

[0015] By combining multiple imaging lengths along multiple specified axes during magnetic resonance imaging, the imaging region during magnetic resonance imaging is obtained.

[0016] The effective coverage area is obtained based on the overlap between the scanning area and the imaging area.

[0017] In some embodiments, obtaining the modulation factor corresponding to each coil unit based on the effective coverage area and the receiving sensitivity of the coil unit includes:

[0018] Obtain the curve representing the change in the receiving sensitivity of the coil unit along the specified axis;

[0019] Calculate the estimated proportion of the local integral area of ​​the curve representing the change in effective coverage area to the total integral area of ​​the curve.

[0020] The modulation factor is obtained based on the estimated ratio.

[0021] In some embodiments, channel merging and reconstruction of magnetic resonance signals received by multiple coil units based on the modulation factor are performed to obtain a magnetic resonance image, including:

[0022] Obtain the spatial relationship of gradient nonlinearity in magnetic resonance imaging space;

[0023] The modulation factor is corrected based on the spatial relationship of the gradient nonlinearity;

[0024] Based on the corrected modulation factor, the magnetic resonance signals received by multiple coil units are channel-merged and reconstructed to obtain a magnetic resonance image.

[0025] In some embodiments, obtaining the modulation factor corresponding to each coil unit based on the effective coverage area and the receiving sensitivity of the coil unit includes:

[0026] Obtain the calculated proportion of the effective coverage area to the coverage area of ​​the coil unit;

[0027] Based on the calculated ratio and the receiving sensitivity of the coil unit, the modulation factor corresponding to each coil unit is obtained.

[0028] Secondly, this embodiment provides a magnetic resonance imaging method, the method comprising:

[0029] The magnetic resonance signal of the object to be detected is acquired. The magnetic resonance signal is acquired simultaneously by multiple coil units, and at least one coil unit is partially outside the magnetic resonance imaging range.

[0030] Obtain the relative positional relationship between each coil unit and the magnetic resonance imaging range;

[0031] The modulation factor is determined for each coil unit based on the relative positional relationship;

[0032] Based on the modulation factor, the magnetic resonance signals received by multiple coil units are channel-merged and reconstructed to obtain a magnetic resonance image.

[0033] In some embodiments, determining the modulation factor for each of the coil units based on the relative positional relationship includes:

[0034] The modulation factor is determined based on the relative positional relationship and the receiving sensitivity of the coil unit; or,

[0035] The modulation factor is determined based on the relative positional relationship and the receiving sensitivity of the coil unit;

[0036] The modulation factor is determined based on the relative positional relationship and the spatial relationship of gradient nonlinearity.

[0037] In some embodiments, the relative position is determined by the projection of the coil unit along a one-dimensional, two-dimensional, or three-dimensional direction into the magnetic resonance imaging range.

[0038] In some embodiments, determining the modulation factor for each of the coil units based on the relative positional relationship includes:

[0039] Obtain the curve representing the change in the receiving sensitivity of the coil unit along the specified axis;

[0040] Calculate the estimated proportion of the local integral area of ​​the curve representing the change in effective coverage area to the total integral area of ​​the curve.

[0041] The modulation factor is obtained based on the estimated ratio;

[0042] or,

[0043] Obtain the calculated proportion of the effective coverage area to the coverage area of ​​the coil unit;

[0044] Based on the calculated ratio and the receiving sensitivity of the coil unit, the modulation factor corresponding to each coil unit is obtained.

[0045] The aforementioned magnetic resonance imaging (MRI) method and adaptive MRI method determine the contribution of each coil unit to MRI based on the effective coverage area between the coil unit's coverage range and the MRI imaging range, as well as the coil unit's ability to receive MRI signals, thus obtaining a modulation factor. The modulation factor allows adjustment of the weights of the MRI signals from each coil unit channel during imaging, balancing the coil unit's contribution to the image signal-to-noise ratio (SNR) while suppressing peripheral artifacts in the image. This solves the problem of balancing SNR and low artifacts in MRI. Attached Figure Description

[0046] Figure 1 is an application environment diagram of a magnetic resonance imaging method in one embodiment;

[0047] Figure 2 is a flowchart of a magnetic resonance imaging method in one embodiment;

[0048] Figure 3 is a schematic diagram of a magnetic resonance imaging scenario in one embodiment;

[0049] Figure 4 is a schematic diagram of a coil unit in one embodiment;

[0050] Figure 5 is a schematic diagram of another magnetic resonance imaging method;

[0051] Figure 6 is a schematic diagram of the modulation factor curve of the coil unit in one embodiment;

[0052] Figure 7 is a sagittal view of the vertebral body scanned in one embodiment;

[0053] Figure 8 is a flowchart of an adaptive magnetic resonance imaging method in one embodiment;

[0054] Figure 9 is a structural block diagram of a magnetic resonance imaging system in one embodiment;

[0055] Figure 10 is an internal structure diagram of a computer device in one embodiment. Detailed Implementation

[0056] 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.

[0057] The magnetic resonance imaging method provided in this application embodiment can be applied to the application environment shown in Figure 1. The terminal 102 communicates with the server 104 via a network. A data storage system can store the data that the server 104 needs to process. The data storage system can be integrated onto the server 104 or placed on a cloud or other network server. The terminal 102 obtains relevant data such as magnetic resonance signals, coil unit coverage, and magnetic resonance imaging range from the server 104, and performs imaging on the magnetic resonance signals based on the above data to obtain a magnetic resonance image. The data storage system can be used to store relevant data and also to store the magnetic resonance image. The terminal 102 can be, but is not limited to, various personal computers, laptops, tablets, and other devices. The server 104 can be implemented using a standalone server or a server cluster composed of multiple servers.

[0058] In one embodiment, as shown in FIG2, a magnetic resonance imaging method is provided. Taking the application of this method to terminal 102 in FIG1 as an example, the method includes the following steps:

[0059] Step S202: Obtain the effective coverage area of ​​multiple coil units within the magnetic resonance imaging range.

[0060] This allows us to obtain the coverage area of ​​each coil unit. Alternatively, we can divide the coil units used in magnetic resonance imaging into groups of multiple adjacent coil units and obtain the coverage area of ​​each group of coil units separately.

[0061] Optionally, a scanning protocol is acquired, and the magnetic resonance imaging range is obtained based on the scanning protocol. If there is an overlap between the coverage area of ​​the coil unit and the magnetic resonance imaging range, the effective coverage area is obtained based on the position information of the overlapping part. This can be achieved by calculating the proportion of the overlapping part to the coverage area of ​​the coil unit, and using this proportion to represent the effective coverage area. Alternatively, the effective coverage area can be obtained through any of the following methods: calculating the overlap position information of the coverage area and the magnetic resonance imaging range in a certain direction; calculating the overlap position information of the coverage area and the magnetic resonance imaging range on a certain plane; or calculating the spatial overlap position information of the coverage area and the magnetic resonance imaging range.

[0062] Step S204: Based on the effective coverage area and the receiving sensitivity of the coil unit, obtain the modulation factor used to indicate the corresponding coil unit.

[0063] The modulation factor indicates the contribution of each coil unit to the magnetic resonance signal-to-noise ratio (SNR). Different positions of the coil unit have varying capabilities in receiving magnetic resonance signals. Based on the coil unit's ability to receive magnetic resonance signals, the intensity of the magnetic resonance signal received within the effective coverage area of ​​the coil unit can be determined. Since the effective coverage area is part of the magnetic resonance imaging range, and the SNR increases accordingly with the intensity of the magnetic resonance signal used for imaging, the contribution of each coil unit to the SNR, i.e., the modulation factor, can be determined based on the intensity of the magnetic resonance signal received within the effective coverage area of ​​the coil unit.

[0064] For the same coil unit, the stronger the intensity of the magnetic resonance signal received within the effective coverage area and the larger the effective coverage area, the higher the contribution of the coil unit to the magnetic resonance signal-to-noise ratio; conversely, the lower the contribution of the coil unit to the magnetic resonance signal-to-noise ratio.

[0065] Step S206: Based on the modulation factor, channel merging and reconstruction of the magnetic resonance signals received by multiple coil units are performed to obtain a magnetic resonance image.

[0066] Specifically, if the contribution of each coil unit to the magnetic resonance signal-to-noise ratio (SNR) is positively correlated with the modulation factor: the higher the contribution of the coil unit to the SNR, the larger the modulation factor; the lower the contribution of the coil unit to the SNR, the smaller the modulation factor. Optionally, the modulation factor can be used as the weight of the coil unit channel, and the magnetic resonance image can be obtained by weighted summation of the magnetic resonance signals of multiple coil unit channels and their corresponding modulation factors.

[0067] If the contribution of each coil unit to the magnetic resonance signal-to-noise ratio (SNR) is negatively correlated with the modulation factor: the lower the contribution of the coil unit to the SNR, the larger the modulation factor; conversely, the higher the contribution of the coil unit to the SNR, the smaller the modulation factor. Optionally, after performing a linear transformation or inversion on the modulation factor, the modulation factor is used as the weight of the coil unit channel. By weighted summing of the magnetic resonance signals of multiple coil unit channels and their corresponding modulation factors, the magnetic resonance image is obtained.

[0068] In related technologies, when the coil unit partially overlaps with the image field of view, there are only two states: selected and unselected. Completely deselecting the coil unit sacrifices the signal-to-noise ratio of magnetic resonance imaging; while completely selecting the coil unit may introduce peripheral artifacts.

[0069] In the aforementioned magnetic resonance imaging (MRI) method, by combining the coverage area of ​​the coil unit and the effective coverage area of ​​the MRI imaging range, as well as the coil unit's ability to receive MRI signals, the contribution of the MRI signal received within the effective coverage area of ​​the coil unit to the MRI is determined. This yields a modulation factor used to indicate the coil unit's contribution to the signal-to-noise ratio (SNR). By adjusting the weights of each coil unit channel during imaging using the modulation factor, the SNR contribution of each coil unit and the negative impact of artifacts can be flexibly balanced. This makes it possible to enhance the weights of coil unit channels with high SNR contributions to improve the SNR, and to reduce the weights of coil unit channels with low SNR contributions to reduce the impact of peripheral artifacts. By adaptively balancing the contribution of coil units to the image SNR while suppressing peripheral artifact signals in the image, optimal overall image quality is obtained, solving the problem of balancing SNR and low artifacts in MRI.

[0070] In one embodiment, obtaining the effective coverage of multiple coil units within the magnetic resonance imaging range includes: obtaining the scan length of each coil unit in a specified axis and the imaging length in the specified axis during magnetic resonance imaging; and obtaining the effective coverage based on the overlap length between the scan length and the imaging length.

[0071] The specified axis refers to one or more pre-set directions. Since the direction of artifact introduction during magnetic resonance imaging is usually related to the PE encoding direction: when the PE encoding direction is along an axis of the FOV (Field of View), the PE direction adjusts synchronously when the user adjusts the FOV direction in the scanning protocol. For example, when the FOV is rotated, the PE direction rotates accordingly. Therefore, the specified axis can be determined according to the scanning protocol. Alternatively, the specified axis can also be pre-determined based on the historical artifact introduction directions of the magnetic resonance system. Optionally, coil elements are generally distributed according to the axes of the coordinate system, and the specified axis can be along one or more axes in the coordinate system.

[0072] Figure 3 is a schematic diagram of a magnetic resonance imaging scenario in this embodiment. As shown in Figure 3, FOV (Field of View) is the image imaging field of view, i.e., the magnetic resonance imaging range in the above embodiment. The left side shows the coil units in relative positions, including three coil units LBA1, LBA2, and LBA3. LBA1, LBA2, and LBA3 can be three coil units individually, or a group of coil units. The scanning length D of coil units LBA1, LBA2, and LBA3 in a specified axis is the sum of A, D, and C during magnetic resonance imaging. The effective coverage area of ​​LBA1 is length A, the effective coverage area of ​​LBA2 is length D, and the effective coverage area of ​​LBA3 is length C. Based on Figure 3, it can be seen that coil unit LBA2 is completely covered by the image field of view, which is a suitable coil unit selection result, and the channel weight corresponding to coil unit LBA2 is 1. LBA1 and LBA3 are not fully covered by the image field of view, so their contribution to the signal-to-noise ratio is limited, and they may also introduce peripheral artifacts. A modulation factor is needed to balance the two. The channel weights corresponding to the LBA1 and LBA3 coil units are less than 1.

[0073] When the imaging range of the coil unit is defined along a direction, artifacts are generally introduced in that direction. Therefore, when the imaging range of the coil unit of the magnetic resonance system is defined along a certain axis, that axis can be used as the specified axis, and the effective coverage range can be obtained according to the overlap length.

[0074] In one embodiment, obtaining the effective coverage area between the coverage area of ​​multiple coil units and the magnetic resonance imaging area includes: obtaining the scanning area of ​​the coil unit by combining multiple scanning lengths in multiple specified axes during coil unit scanning; obtaining the imaging area during magnetic resonance imaging by combining multiple imaging lengths in multiple specified axes during magnetic resonance imaging; and obtaining the effective coverage area based on the overlapping area between the scanning area and the imaging area.

[0075] If two specified axial directions are set, a plane can be obtained based on these two axes. This allows for the determination of the coil unit's coverage area's position on this plane, as well as its position during magnetic resonance imaging (MRI), and the overlap position information between the coverage area and the MRI range. The overlap position information can be data such as the planar coordinates and area of ​​the overlapping region. Optionally, when the coil units are distributed and defined along two specified axes in a preset coordinate system, artifacts may be introduced along both axes. The effective coverage area on the plane formed by the two specified axes is then obtained.

[0076] If three specified axes are set, the positional information of the coil unit coverage area in three-dimensional space, as well as its positional information in three-dimensional space during magnetic resonance imaging, can be obtained based on these axes. The overlap positional information between the coverage area and the magnetic resonance imaging area can also be obtained. The overlap positional information can be data such as the spatial coordinates and volume of the overlapping region in three-dimensional space. Optionally, if the coil units are distributed and defined along the three specified axes in a preset coordinate system, artifact suppression in three-dimensional space may be necessary. Therefore, obtaining the effective coverage area in the space formed by the three specified axes is crucial.

[0077] In this embodiment, the coverage area of ​​the coil unit and the magnetic resonance imaging range are determined based on a specified axis, and a modulation factor with multiple degrees of freedom in multiple directions is obtained. This allows for the suppression of peripheral artifacts introduced in different directions, improving the suppression effect and making the magnetic resonance imaging method widely applicable to all clinical scenarios.

[0078] In one embodiment, obtaining the modulation factor corresponding to each coil based on the effective coverage area and the receiving sensitivity of the coil unit includes: acquiring a curve representing the change in the receiving sensitivity of the coil unit along a specified axis; calculating an estimated proportion of the local integral area of ​​the curve representing the effective coverage area to the total integral area of ​​the curve; and obtaining the modulation factor based on the estimated proportion.

[0079] The receiver sensitivity curve indicates how the magnetic resonance signal response intensity changes with position within the coverage area of ​​the coil unit. A higher estimation ratio indicates a greater contribution of the coil unit to the magnetic resonance signal-to-noise ratio (SNR) along a specified axis; conversely, a lower estimation ratio indicates a lower contribution. Based on the estimation ratio, the effective coverage area of ​​the coil unit is determined, leading to the modulation factor, which helps to remove peripheral artifacts.

[0080] Furthermore, in one embodiment, the modulation factor corresponding to each coil unit is obtained based on the effective coverage area and the receiving sensitivity of the coil unit, including: obtaining the spatial relationship of gradient nonlinearity in the magnetic resonance imaging space; correcting the modulation factor based on the spatial relationship of gradient nonlinearity; and performing channel merging and reconstruction on the magnetic resonance signals received by multiple coil units based on the corrected modulation factor to obtain a magnetic resonance image.

[0081] The gradient magnetic field obtained by the magnetic resonance imaging (MRI) device is not perfectly uniform. The spatial relationship of the gradient nonlinearity can be obtained based on the spatial variation of the gradient magnetic field strength. Optionally, based on the spatial relationship of the gradient nonlinearity, the mapping relationship between the gradient relationship and the magnetic resonance signal response intensity within the effective coverage area, and the mapping relationship between the receiving sensitivity of the coil unit and the magnetic resonance signal response intensity within the effective coverage area, can be obtained. Based on these two mapping relationships, the contribution ratio of the effective coverage area of ​​the coil unit to the magnetic resonance signal can be determined, thus obtaining the corrected modulation factor.

[0082] In this embodiment, by comprehensively considering the spatial relationship between the coverage area of ​​the coil unit and the magnetic field imaging range, as well as the spatial relationship between the coverage area of ​​the coil unit and the nonlinear characteristics of the magnetic field gradient, a mapping relationship between the effective coverage area of ​​the coil unit and the magnetic resonance signal-to-noise ratio (SNR) is obtained. Depending on the magnetic resonance equipment and the scanned object, the mapping relationship between the effective coverage area of ​​the coil unit and the SNR can be linear, nonlinear, or correlated with curves or surfaces such as sensitivity characteristics. This ensures accurate calculation of the modulation factor, enabling the magnetic resonance imaging method to obtain magnetic resonance images with low artifacts and high SNR in various applications.

[0083] In one embodiment, the modulation factor corresponding to each coil unit is obtained based on the effective coverage area and the receiving sensitivity of the coil unit, including: obtaining the calculated proportion of the effective coverage area to the coverage area of ​​the coil unit; and obtaining the modulation factor corresponding to each coil unit based on the calculated proportion and the receiving sensitivity of the coil unit.

[0084] The calculated ratio can be obtained based on the coordinate relationship between the effective coverage area and the coverage area. The larger the calculated ratio of the effective coverage area to the coil unit's coverage area, the greater the impact of the magnetic resonance signal received by the coil unit on the magnetic resonance signal-to-noise ratio. The higher the receiving sensitivity of the coil unit, the stronger the magnetic resonance signal detected within the specified range, and the greater the contribution of the coil unit to the signal-to-noise ratio.

[0085] Optionally, based on the receiving sensitivity of the coil unit within the effective coverage area, the contribution of the coil unit to the magnetic resonance signal-to-noise ratio is obtained, that is, the modulation factor when the magnetic resonance signal received by the coil unit is channel-merged and reconstructed, and the magnetic resonance image is obtained based on the modulation factor to achieve the effect of removing artifacts in the magnetic resonance image.

[0086] In one embodiment, a coil unit is the smallest imaging unit in the magnetic resonance imaging process. The effective coverage and modulation factor of a single coil unit can be calculated individually, or multiple adjacent coil units can be grouped together, and the effective coverage and modulation factor of each group can be calculated separately. Figure 4 is a schematic diagram of a coil unit in this embodiment. As shown in Figure 4, the sum of the coverage areas of the multiple coil units selected for magnetic resonance imaging is greater than the field of view (FOV) of the magnetic resonance imaging. In this embodiment, by dividing the coil units, the calculation accuracy of the modulation factor can be flexibly adjusted.

[0087] In one embodiment, obtaining a magnetic resonance image based on the magnetic resonance signals of multiple coil unit channels and their corresponding modulation factors includes: merging the channels of the multiple coil units according to the modulation factors; and obtaining a magnetic resonance image based on the merged magnetic resonance signals. The modulation factors of the coil units are used as weights for the corresponding channels of the coil units. After adjusting the magnetic resonance signals acquired by the channels of the multiple coil units based on these weights, the channels of the multiple coil units are merged, thereby reconstructing a magnetic resonance image based on the merged magnetic resonance signals.

[0088] Optionally, the magnetic resonance system includes multiple coil channels, and the modulation factor is used as the weight of the corresponding channel of the coil unit to perform weighted merging of the magnetic resonance signals acquired by multiple channels to obtain a magnetic resonance image.

[0089] In one embodiment, Figure 5 provides a flowchart of another magnetic resonance imaging method. As shown in Figure 5, the steps include:

[0090] Step S501, the FOV covers the coverage area of ​​multiple coil units.

[0091] When the FOV covers the coverage area of ​​multiple coils, the FOV coverage area is relatively large. The position of coil units outside the FOV (imaging range) is likely to deviate from the center of the magnet, and there is a possibility of artifacts in the magnetic resonance image.

[0092] Further, after determining that the FOV covers at least a single coil unit, and simultaneously determining that the PE direction is along the magnetic field direction, step S502 is executed. This setting is because when the PE encoding direction is along the magnetic field direction, i.e., the patient's head-to-toe direction, peripheral artifacts are easily superimposed in the MRI image. Understandably, the determination of the correlation between the PE direction and the magnetic field direction can be adjusted according to the artifact introduction situation in actual applications.

[0093] Step S502: Enable the adaptive modulation factor scheme;

[0094] Step S503: Obtain the imaging range in the direction of the magnetic field;

[0095] Step S504: Obtain the position and length of the selected coil unit in the image;

[0096] Step S505: Traverse the relationship between each coil unit and the image imaging range, and calculate the coverage ratio of the coil unit;

[0097] Step S506: Obtain the modulation factor of the coil unit based on the coverage ratio, and use it for channel merging and reconstruction.

[0098] For example, using a sagittal MRI image of the vertebral body as an example: the image imaging range (FOV) is 350 mm, the phase encoding direction is along the head-to-foot axis, and the selected coil units in the image are, from top to bottom, coil units SP1, SP2, and SP3. To suppress peripheral artifacts, after enabling the modulation factor scheme, the MRI imaging range of the image in the magnetic field direction is obtained as 350 mm; and the positions of the selected coil units in the image and the lengths of the coil units in the magnetic field direction are obtained. By traversing the relationship between each coil unit and the image imaging range, the coverage range of the coil unit in the magnetic field direction, i.e., the overlap length, is calculated, and the coverage ratio of the coil unit is obtained based on the overlap length and the length of the coil unit group in the magnetic field direction.

[0099] The modulation factor of the coil unit is obtained by evaluating the coverage ratio and the receiving sensitivity characteristics of the coil unit. The receiving sensitivity characterizes the strength of the received signal from the coil unit, i.e., its contribution to the signal-to-noise ratio (SNR). Figure 6 is a schematic diagram of the modulation factor curve of a coil unit in this embodiment. As shown in Figure 6, the receiving sensitivity of the coil unit LBA1 is approximated as a parabolic curve, with strong signal reception at the center and weak reception at the edges. Based on the overlap length between the coverage area and the imaging range of the coil unit, the integral of the area of ​​the coil unit's coverage area corresponding to the overlap length can be obtained, i.e., the sum of the coverage and receiving areas. Based on the sum of the coverage and receiving areas and the coverage range, the coverage ratio of the coil unit can be obtained. Combining the area curves of the coil unit's coverage ratio and the receiving sensitivity, the contribution to the SNR is estimated, resulting in the modulation factor curve.

[0100] The formula for the receiving sensitivity of the coil unit is as follows:

[0101]

[0102] By combining the integral of the area covered by the coil unit corresponding to the overlap length and the formula for the receiving sensitivity of the coil unit, the modulation factor formula can be obtained:

[0103]

[0104] Where x represents the coverage length of the coil unit, and D represents the length of the coil unit.

[0105] Alternatively, the modulation factor formula can be obtained:

[0106] y = -2a 3 +3a 2

[0107] Where 'a' represents the coil unit coverage ratio, and the coil unit coverage ratio = overlap length / coil unit length.

[0108] According to the formula for the modulation factor, the modulation factor can be calculated under any coil unit coverage ratio. When the coil unit coverage ratio is 0, the modulation factor is 0, and when the coil unit coverage ratio is 1, the modulation factor is 1.

[0109] The formula for calculating based on the modulation factor is: y = -2a 3 +3a 2 The data for the coil unit is as follows:

[0110] The coverage ratio a of coil unit SP1 = overlap length / coil unit length = 12.3 / 180 = 0.0683, modulation factor = 0.0134;

[0111] The coverage ratio of coil unit SP2 is a = overlap length / coil unit length = 180 / 180 = 1, and the modulation factor is 1;

[0112] Coil unit coverage ratio a = overlap length / coil unit length = 127.6 / 180 = 0.708, modulation factor = 0.794.

[0113] After obtaining the modulation factor of each coil unit group, the modulation factor is used as the weight of the coil unit channel to merge and reconstruct multiple coil unit channels, thereby achieving the effect of removing peripheral artifacts. Figure 7 is a sagittal image of the vertebral body scanned in this embodiment. In Figure 7(a), the magnetic resonance image is not modulated based on the modulation factor, and the artifacts are severe. Figure 7(a) is the magnetic resonance image modulated based on the modulation factor, and the artifacts are effectively suppressed.

[0114] It should be understood that data such as the imaging range of magnetic resonance images, the length and number of coil units, and the calculation formula of the modulation factor can all be set and modified according to actual application requirements, and there are no restrictions on them.

[0115] The method for modulating the coil unit in this embodiment assigns different weights to coil units at different spatial locations through an automatic algorithm. This suppresses peripheral artifacts while maximizing the preservation of the signal-to-noise ratio contribution of the coil unit channels, thereby improving image quality during the automatic adjustment process.

[0116] 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 S503 and S504 can be executed at the same time, or they can be executed in other orders.

[0117] Based on the same inventive concept, this application also provides an adaptive magnetic resonance imaging method. The solutions provided by the adaptive magnetic resonance imaging method in one or more of the following embodiments are similar to the solutions described in the above methods. Therefore, the specific limitations of the one or more adaptive magnetic resonance imaging method embodiments provided below can be found in the limitations of the magnetic resonance imaging method described above, and will not be repeated here. In one embodiment, Figure 8 provides a flowchart of an adaptive magnetic resonance imaging method. As shown in Figure 8, the method includes:

[0118] Step S801: Acquire the magnetic resonance signal of the object to be detected. The magnetic resonance signal is acquired simultaneously by multiple coil units, and at least one part of the coil unit is outside the magnetic resonance imaging range.

[0119] When a portion of the coil unit is outside the magnetic resonance imaging range, the position of the coil unit outside the magnetic resonance imaging range is likely to deviate from the center of the magnet, resulting in artifacts in the magnetic resonance image.

[0120] Step S802: Obtain the relative positional relationship between each coil unit and the magnetic resonance imaging range, and determine the modulation factor for each coil unit based on the relative positional relationship.

[0121] The relative positional relationship is used to indicate the spatial positional relationship of the scanning range of each coil unit relative to the magnetic resonance imaging range. When a coil unit extends beyond the imaging range, it may enter the non-ideal region of the main magnetic field and gradient field. This coil unit not only contributes limitedly to the signal-to-noise ratio of the image but also easily introduces the aforementioned peripheral artifacts. The influence of the magnetic resonance signal received by the coil unit on the magnetic resonance image can be reduced by using a modulation factor. Optionally, based on the relative positional information, the positional information of the overlapping portion between the scanning range of each coil unit and the magnetic resonance imaging range is determined, thereby obtaining the effective coverage range of the coil unit within the magnetic resonance imaging range. The modulation factor is then determined based on the effective coverage range of each coil unit.

[0122] Step S803: Based on the modulation factor, channel merging and reconstruction of the magnetic resonance signals received by multiple coil units are performed to obtain a magnetic resonance image.

[0123] Optionally, by obtaining the relative positional relationship, the contribution of each coil unit to the magnetic resonance signal-to-noise ratio can be determined, and then the corresponding modulation factor can be obtained based on the contribution. Based on the modulation factor, the weight of the corresponding channel of the coil unit can be obtained, and the magnetic resonance signals acquired by multiple channels can be weighted and merged to obtain a magnetic resonance image.

[0124] In this embodiment, based on the relative positional relationship between multiple coil units and the magnetic resonance imaging range, a modulation factor is obtained to adjust the contribution of each coil unit to magnetic resonance imaging. By combining the magnetic resonance signal channels through the modulation factor, the imaging effect of coil units that introduce artifacts on the magnetic resonance image can be reduced, thus solving the problem that it is impossible to balance signal-to-noise ratio and low artifacts in magnetic resonance imaging.

[0125] In one embodiment, determining the modulation factor for each coil unit based on the relative positional relationship includes: determining the modulation factor based on the relative positional relationship and the receiving sensitivity of the coil unit; or, determining the modulation factor based on the relative positional relationship and the spatial relationship of gradient nonlinearity.

[0126] Optionally, the contribution of the coil unit to the magnetic resonance signal-to-noise ratio can be obtained by combining the receiving sensitivity of the coil unit within the effective coverage area, thus obtaining the modulation factor.

[0127] Optionally, the effective coverage area of ​​the coil unit within the magnetic resonance imaging range can be obtained based on the relative positional relationship. The mapping relationship between the gradient within the effective coverage area and the magnetic resonance signal response intensity can be obtained based on the gradient nonlinearity of the spatial relationship. Based on this mapping relationship, the contribution ratio of the effective coverage area of ​​the coil unit to the magnetic resonance signal can be determined, thus obtaining the modulation factor. Furthermore, after determining the modulation factor based on the relative positional relationship and the receiving sensitivity of the coil unit, the modulation factor can be corrected based on the gradient nonlinearity of the spatial relationship.

[0128] In one embodiment, determining the modulation factor for each coil unit based on its relative positional relationship includes: obtaining a curve representing the change in receiving sensitivity of the coil unit along a specified axis; calculating an estimated proportion of the local integral area of ​​the curve representing the effective coverage area to the total integral area of ​​the curve; and obtaining the modulation factor based on the estimated proportion. Alternatively, determining the modulation factor for each coil unit based on its relative positional relationship includes: obtaining a calculated proportion of the effective coverage area to the coverage area of ​​the coil unit; and obtaining the modulation factor corresponding to each coil unit based on the calculated proportion and the receiving sensitivity of the coil unit.

[0129] In one embodiment, the relative positional relationship is determined by the projection of the coil units along a one-dimensional, two-dimensional, or three-dimensional direction within the magnetic resonance imaging range. Optionally, the scan length of each coil unit along a specified axis and the imaging length along the specified axis during magnetic resonance imaging can be obtained; the relative positional relationship in the one-dimensional direction is obtained based on the overlap length between the scan length and the imaging length. Alternatively, the scan area on a specified plane defined by any two specified axes during coil unit scanning and the imaging area on the aforementioned specified plane during magnetic resonance imaging can be obtained; the relative positional relationship in the two-dimensional direction is obtained based on the overlap area between the scan area and the imaging area. Alternatively, the scan area in three-dimensional space during coil unit scanning and the imaging area in three-dimensional space during magnetic resonance imaging can be obtained; the relative positional relationship in the three-dimensional direction is obtained based on the overlap area between the scan area and the imaging area.

[0130] Optionally, multiple coil units are arranged in rows and columns; coil units belonging to the same row share a modulation factor. Alternatively, multiple adjacent coil units or coil units belonging to the same column can share a modulation factor.

[0131] 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.

[0132] This embodiment provides a magnetic resonance imaging system, as shown in FIG9. The magnetic resonance imaging system includes: a scanning device and a computer device, wherein the scanning device is connected to the computer device; wherein the scanning device is used to acquire magnetic resonance signals; the computer device includes a memory and a processor, the memory stores a computer program, and the processor executes the computer program to implement the magnetic resonance imaging method in any method embodiment.

[0133] In one embodiment, a computer device is provided, which may be a terminal, and its internal structure diagram is shown in Figure 10. The computer device includes a processor, memory, input / output interface, communication interface, display unit, and input device. The processor, memory, and input / output interface are connected via a system bus, and the communication interface, display unit, and input device are also connected to the system bus via the input / output interface. The processor of the computer device provides computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The input / output interface of the computer device is used for exchanging information between the processor and external devices. The communication interface of the computer device is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, mobile cellular networks, NFC (Near Field Communication), or other technologies. When the computer program is executed by the processor, it implements a magnetic resonance imaging method. The display unit of the computer device is used to form a visually visible image and may be a display screen, projection device, or other similar device. The input device of the computer device can be a touch layer covering the display screen, or buttons, trackballs, or touchpads set on the computer device casing, or external keyboards, touchpads, or mice, etc.

[0134] Those skilled in the art will understand that the structure shown in Figure 10 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 may combine certain components, or may have different component arrangements.

[0135] 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.

[0136] 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.

[0137] 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.

[0138] 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.

[0139] 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.

[0140] 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: acquiring the effective coverage area of ​​multiple coil units within the magnetic resonance imaging range; obtaining the modulation factor corresponding to each coil unit based on the effective coverage area and the receiving sensitivity of the coil unit; and performing channel merging and reconstruction on the magnetic resonance signals received by the multiple coil units based on the modulation factor to obtain a magnetic resonance image.

2. The method according to claim 1, characterized in that, The effective coverage area of ​​multiple coil units within the magnetic resonance imaging range is obtained by: obtaining the scan length of each coil unit in a specified axis, and the imaging length in the specified axis during magnetic resonance imaging; and obtaining the effective coverage area based on the overlap length between the scan length and the imaging length.

3. The method according to claim 1, characterized in that, The effective coverage of multiple coil units within the magnetic resonance imaging range is obtained by: combining multiple scan lengths along multiple specified axes during the scanning of the coil unit to obtain the scanning area of ​​the coil unit; combining multiple imaging lengths along multiple specified axes during magnetic resonance imaging to obtain the imaging area during magnetic resonance imaging; and obtaining the effective coverage based on the overlap area between the scanning area and the imaging area.

4. The method according to claim 1, characterized in that, The step of obtaining the modulation factor corresponding to each coil unit based on the effective coverage range and the receiving sensitivity of the coil unit includes: obtaining a curve representing the change in the receiving sensitivity of the coil unit along a specified axis; calculating an estimated proportion of the local integral area of ​​the curve representing the change in the effective coverage range relative to the total integral area of ​​the curve; and obtaining the modulation factor based on the estimated proportion.

5. The method according to claim 1, characterized in that, The process of channel merging and reconstruction of magnetic resonance signals received by multiple coil units according to the modulation factor to obtain a magnetic resonance image includes: acquiring the spatial relationship of gradient nonlinearity in the magnetic resonance imaging space; correcting the modulation factor according to the spatial relationship of gradient nonlinearity; and performing channel merging and reconstruction of magnetic resonance signals received by multiple coil units according to the corrected modulation factor to obtain a magnetic resonance image.

6. The method according to claim 1, characterized in that, The step of obtaining the modulation factor corresponding to each coil unit based on the effective coverage range and the receiving sensitivity of the coil unit includes: obtaining a calculated proportion of the effective coverage range to the coverage range of the coil unit; and obtaining the modulation factor corresponding to each coil unit based on the calculated proportion and the receiving sensitivity of the coil unit.

7. An adaptive magnetic resonance imaging method, characterized in that, The method includes: acquiring magnetic resonance signals of the object to be detected, wherein the magnetic resonance signals are acquired simultaneously by multiple coil units, and at least one coil unit is partially outside the magnetic resonance imaging range; acquiring the relative positional relationship between each coil unit and the magnetic resonance imaging range; determining a modulation factor for each coil unit according to the relative positional relationship; and performing channel merging and reconstruction on the magnetic resonance signals received by the multiple coil units according to the modulation factor to obtain a magnetic resonance image.

8. The method according to claim 7, characterized in that, Determining the modulation factor for each coil unit based on the relative positional relationship includes: determining the modulation factor based on the relative positional relationship and the receiving sensitivity of the coil unit; or, determining the modulation factor based on the relative positional relationship and the spatial relationship of gradient nonlinearity.

9. The method according to claim 7, characterized in that, Determining the modulation factor for each coil unit based on the relative positional relationship includes: obtaining the effective coverage area of ​​multiple coil units within the magnetic resonance imaging range based on the relative positional relationship; obtaining a curve representing the change in receiving sensitivity of the coil unit along a specified axis; calculating an estimated proportion of the local integral area of ​​the change curve relative to the total integral area of ​​the change curve; obtaining the modulation factor based on the estimated proportion; or, obtaining the effective coverage area of ​​multiple coil units within the magnetic resonance imaging range based on the relative positional relationship; obtaining a calculated proportion of the effective coverage area relative to the coverage area of ​​the coil unit; obtaining the modulation factor corresponding to each coil unit based on the calculated proportion and the receiving sensitivity of the coil unit.

10. The method according to claim 7, characterized in that, The relative positional relationship is determined by the projection of the coil unit along a one-dimensional, two-dimensional, or three-dimensional direction within the magnetic resonance imaging range.

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