Radio frequency field non-uniformity correction method and device, electronic equipment and program product

Abstract

The invention is suitable for the technical field of magnetic resonance imaging, and provides a radio frequency field non-uniformity correction method and device, electronic equipment and a program product. The method comprises the following steps: acquiring actual radio frequency field intensity of each position in a scanning object under two preset radio frequency field intensities and actual CEST signal intensity at a first chemical shift position and a second chemical shift position; determining a first ideal CEST signal intensity based on the actual radio frequency field intensity of the same position under the two preset radio frequency field intensities and the actual CEST signal intensity at the first chemical shift; determining a second ideal CEST signal intensity based on the actual radio frequency field intensity of the same position under the two preset radio frequency field intensities and the actual CEST signal intensity at the second chemical shift; and determining the GluCEST signal intensity based on the two ideal CEST signal intensities at the same position under the target radio frequency field intensity. According to the invention, the accuracy of GluCEST signal strength measurement can be improved.

Description

Technical Field

[0001] The present application belongs to the field of magnetic resonance imaging technology, and in particular relates to a method, device, electronic equipment and program product for correcting radio frequency field inhomogeneity. Background Art

[0002] Chemical exchange saturation transfer (CEST) magnetic resonance imaging is a highly sensitive molecular imaging technique capable of detecting endogenous metabolites and compounds (such as glutamate, glycogen, and amide protons) as well as exogenous paramagnetic / diamagnetic CEST contrast agents in the tissue microenvironment. By selectively saturating the exchangeable protons in target molecules, changes in the magnetization of free water are observed, indirectly revealing information such as the target molecule's content and chemical exchange rate. Glutamate is a major neurotransmitter that plays a critical role in maintaining normal central nervous system function. Glutamate CEST (GluCEST) imaging visualizes glutamate by detecting the chemical exchange between free water and amine protons in glutamate. Because the chemical exchange rate of amine protons is relatively rapid under physiological temperature and pH conditions, GluCEST imaging must be performed at high magnetic field strengths. However, high-field clinical scanners exhibit significant radiofrequency field (B1) inhomogeneities, which can affect the accuracy of GluCEST signal intensity measurements. Summary of the Invention

[0003] The embodiments of the present application provide a method, device, electronic device, and program product for correcting radio frequency field inhomogeneity, which can improve the accuracy of GluCEST signal strength measurement.

[0004] In a first aspect, an embodiment of the present application provides a method for correcting radio frequency field inhomogeneity, comprising: When the radio frequency field intensity is a first preset radio frequency field intensity, obtaining a first actual radio frequency field intensity at each position in the scanned object, a first actual chemical exchange saturation transfer (CEST) signal intensity at a first chemical shift, and a second actual CEST signal intensity at a second chemical shift, wherein the first chemical shift is the chemical shift of glutamate, and the second chemical shift is the chemical shift of the glutamate relative to the opposite side of a water molecule; acquiring, when the radio frequency field intensity is a second preset radio frequency field intensity, a second actual radio frequency field intensity at each position in the scanned object, a third actual CEST signal intensity at the first chemical shift, and a fourth actual CEST signal intensity at the second chemical shift, wherein the second preset radio frequency field intensity is different from the first preset radio frequency field intensity; determining a first ideal CEST signal intensity at the first chemical shift at the corresponding position under a target radio frequency field intensity based on the first actual radio frequency field intensity, the first actual CEST signal intensity, the second actual radio frequency field intensity, and the third actual CEST signal intensity at the same position; determining a second ideal CEST signal intensity at the second chemical shift at the corresponding position under the target radio frequency field intensity based on the first actual radio frequency field intensity, the second actual CEST signal intensity, the second actual radio frequency field intensity, and the fourth actual CEST signal intensity at the same position; Based on the first ideal CEST signal intensity and the second ideal CEST signal intensity at the same position at the target radio frequency field intensity, the glutamate GluCEST signal intensity at the corresponding position at the target radio frequency field intensity is determined.

[0005] In an embodiment of the present application, by obtaining the actual radio frequency field intensity at each position in the scanned object under two preset radio frequency field intensities, the actual CEST signal intensity at the chemical shift of glutamate, and the actual CEST signal intensity at the chemical shift of glutamate on the opposite side of the water molecule, and based on the actual radio frequency field intensity at the two preset radio frequency field intensities and the actual CEST signal intensity at the chemical shift of glutamate at the same position, the CEST signal intensity at the chemical shift of glutamate at the target radio frequency field intensity can be corrected, thereby obtaining the ideal CEST signal intensity at the chemical shift of glutamate at the target radio frequency field intensity, thereby achieving correction of radio frequency field inhomogeneity. The correction is based on the actual RF field intensity at the same position under two preset RF field intensities and the actual CEST signal intensity at the chemical shift of glutamate relative to the opposite side of the water molecule. The CEST signal intensity at the chemical shift of glutamate relative to the opposite side of the water molecule at the target RF field intensity at this position can be corrected, thereby obtaining the ideal CEST signal intensity at the chemical shift of glutamate relative to the opposite side of the water molecule at this position under the target RF field intensity, thereby realizing the correction of RF field uniformity. Based on the above two ideal CEST signal intensities at the same position under the target RF field intensity, the GluCEST signal intensity at this position under the target RF field intensity can be accurately measured.

[0006] In a second aspect, an embodiment of the present application provides a radio frequency field inhomogeneity correction device, comprising: a first acquisition module, configured to acquire, when the radio frequency field intensity is a first preset radio frequency field intensity, a first actual chemical exchange saturation transfer (CEST) signal intensity at a first chemical shift, and a second actual CEST signal intensity at a second chemical shift at each position in the scanned object, wherein the first chemical shift is a chemical shift of glutamate, the second chemical shift is a chemical shift of the glutamate relative to the opposite side of a water molecule, and the second preset radio frequency field intensity is different from the first preset radio frequency field intensity; a second acquisition module, configured to acquire, when the radio frequency field intensity is a second preset radio frequency field intensity, a second actual radio frequency field intensity at each position in the scanned object, a third actual CEST signal intensity at the first chemical shift, and a fourth actual CEST signal intensity at the second chemical shift; a first determining module, configured to determine a first ideal CEST signal intensity at the first chemical shift at the corresponding position under a target radio frequency field intensity based on the first actual radio frequency field intensity, the first actual CEST signal intensity, the second actual radio frequency field intensity, and the third actual CEST signal intensity at the same position; a second determining module, configured to determine a second ideal CEST signal intensity at the second chemical shift at the corresponding position under the target radio frequency field intensity based on the first actual radio frequency field intensity, the second actual CEST signal intensity, the second actual radio frequency field intensity, and the fourth actual CEST signal intensity at the same position; The third determination module is configured to determine the glutamate GluCEST signal intensity at the corresponding position under the target radio frequency field intensity based on the first ideal CEST signal intensity and the second ideal CEST signal intensity at the same position under the target radio frequency field intensity.

[0007] In a third aspect, an embodiment of the present application provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the electronic device implements the radio frequency field non-uniformity correction method as described in any one of the first aspects above.

[0008] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a computer, the method for correcting radio frequency field inhomogeneity as described in the first aspect above is implemented.

[0009] In a fifth aspect, an embodiment of the present application provides a computer program product, including a computer program. When the computer program is executed, the radio frequency field non-uniformity correction method as described in any one of the first aspects above is executed.

[0010] It can be understood that the beneficial effects of the second to fifth aspects mentioned above can be found in the relevant description of the first aspect mentioned above, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0012] Figure 1 1 is a flow chart of a method for correcting radio frequency field inhomogeneity provided in an embodiment of the application; Figure 2 is a distribution diagram of brain GluCEST signal intensity before correction provided in the examples of the present application; Figure 3 is an example diagram of the radio frequency field correction result based on the first linear function provided in an embodiment of the present application; Figure 4 is an example diagram of the radio frequency field correction result based on the second linear function provided in an embodiment of the present application; Figure 5 is a distribution diagram of the corrected brain GluCEST signal intensity provided in the examples of the present application; Figure 6 Schematic diagram of the structure of the radio frequency field non-uniformity correction device provided in an embodiment of the present application; Figure 7 It is a structural diagram of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0013] In the following description, specific details such as specific system structures and techniques are provided for purposes of illustration rather than limitation to facilitate a thorough understanding of the embodiments of the present application. However, it will be apparent to those skilled in the art that the present application may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid obscuring the description of the present application with unnecessary detail.

[0014] It should be understood that when used in the present specification and the appended claims, the term "comprising" indicates the presence of described features, integers, steps, operations, elements and / or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or collections thereof.

[0015] It will also be understood that the term "and / or" used in this specification and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0016] As used in this specification and the appended claims, the term "if" can be interpreted as "when" or "upon" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrase "if it is determined" or "if [described condition or event] is detected" can be interpreted as meaning "upon determination" or "in response to determining" or "upon detection of [described condition or event]" or "in response to detecting [described condition or event]," depending on the context.

[0017] In addition, in the description of the present application specification and the appended claims, the terms "first", "second", "third", etc. are only used to distinguish the descriptions and cannot be understood as indicating or implying relative importance.

[0018] References to "one embodiment" or "some embodiments" in this specification mean that a particular feature, structure, or characteristic described in conjunction with that embodiment is included in one or more embodiments of the present application. Thus, phrases such as "in one embodiment," "in some embodiments," "in other embodiments," and "in other embodiments" appearing in various places in this specification do not necessarily refer to the same embodiment, but rather mean "one or more but not all embodiments," unless otherwise specifically emphasized. The terms "including," "comprising," "having," and variations thereof all mean "including but not limited to," unless otherwise specifically emphasized.

[0019] The radio frequency field non-uniformity correction method provided in the embodiments of the present application can be applied to electronic devices such as mobile phones, tablet computers, magnetic resonance imaging equipment, laptop computers, ultra-mobile personal computers (UMPCs), netbooks, and personal digital assistants (PDAs). The embodiments of the present application do not impose any restrictions on the specific types of electronic devices.

[0020] See also Figure 1 , Figure 1 A flow chart of a method for correcting radio frequency field inhomogeneity provided in an embodiment of the present application is shown. As an example and not a limitation, the method includes the following steps: Step 101 : When the RF field intensity is a first preset RF field intensity, a first actual RF field intensity at each position in a scanned object, a first actual CEST signal intensity at a first chemical shift, and a second actual CEST signal intensity at a second chemical shift are acquired.

[0021] The first chemical shift is the chemical shift of glutamic acid, which is typically 3 ppm. The second chemical shift is the chemical shift of glutamic acid relative to the opposite side of a water molecule, which is typically -3 ppm. It should be understood that a chemical shift can be understood as a frequency shift.

[0022] The aforementioned scanning object is a scanning object of a magnetic resonance imaging device. This application does not limit the specific type of scanning object. As an example and not a limitation, the scanning object is the brain of a human or animal. Since the brain is three-dimensional, a specific layer or slice of the brain can be selected for imaging, that is, a specific layer or slice of the brain can be scanned.

[0023] When the RF field strength of the magnetic resonance imaging device is a first preset RF field strength, due to the significant RF field inhomogeneity of the magnetic resonance imaging device under high magnetic field strength, the actual RF field strength at various locations in the scanned object generally deviates from the first preset RF field strength, or the actual RF field strength at some locations in the scanned object deviates from the first preset RF field strength. Based on this, the actual CEST signal strength at the first chemical shift may be different from the ideal CEST signal strength at the first chemical shift when the actual RF field strength at the corresponding location reaches the first preset RF field strength, and the actual CEST signal strength at the second chemical shift may be different from the ideal CEST signal strength at the second chemical shift when the actual RF field strength at the corresponding location reaches the first preset RF field strength. Therefore, the electronic device can execute step 101 and perform RF field inhomogeneity correction based on the data obtained in step 101 to achieve accurate measurement of the GluCEST signal strength. It should be understood that the measurement of the GluCEST signal strength can be understood as the quantification of the GluCEST signal strength.

[0024] In one embodiment, the electronic device can obtain a first relative spatial distribution map of the radio frequency field when the radio frequency field strength is a first preset radio frequency field strength. The first relative spatial distribution map includes the ratio of the first actual radio frequency field strength at each position in the scanned object to the first preset radio frequency field strength. Therefore, by multiplying the first preset radio frequency field strength by the first relative spatial distribution map, the first actual radio frequency field strength at each position in the scanned object can be obtained.

[0025] In a possible implementation, for any position in the scanned object, a method for acquiring the first actual CEST signal strength and the second actual CEST signal strength at the position includes: When the radio frequency field intensity is a first preset radio frequency field intensity, acquiring a magnetic resonance signal intensity image of a first radio frequency pulse mark at a first chemical shift and a magnetic resonance signal intensity image of a second radio frequency pulse mark at a second chemical shift; determining a first actual CEST signal intensity from a first radio frequency pulse labeled magnetic resonance signal intensity image; A second actual CEST signal intensity is determined from the magnetic resonance signal intensity image of the second radio frequency pulse labeling.

[0026] The first radio frequency pulse-marked magnetic resonance signal intensity image includes the radio frequency pulse-marked magnetic resonance signal intensity at each location in the scanned object at a first chemical shift when the radio frequency field intensity is a first preset radio frequency field intensity. For any location in the scanned object, the radio frequency pulse-marked magnetic resonance signal intensity at the first chemical shift in the first radio frequency pulse-marked magnetic resonance signal intensity image can be determined as the first actual CEST signal intensity.

[0027] The second radio frequency pulse-labeled magnetic resonance signal intensity image includes the radio frequency pulse-labeled magnetic resonance signal intensity at each location in the scanned object at the second chemical shift when the radio frequency field intensity is the first preset radio frequency field intensity. For any location in the scanned object, the radio frequency pulse-labeled magnetic resonance signal intensity at the second chemical shift in the second radio frequency pulse-labeled magnetic resonance signal intensity image can be determined as the second actual CEST signal intensity.

[0028] Step 102 : When the RF field intensity is a second preset RF field intensity, a second actual RF field intensity at each position in the scanned object, a third actual CEST signal intensity at the first chemical shift, and a fourth actual CEST signal intensity at the second chemical shift are acquired.

[0029] The second preset radio frequency field strength is different from the first preset radio frequency field strength, that is, the second preset radio frequency field strength is not equal to the first preset radio frequency field strength.

[0030] Optionally, the first preset RF field strength and the second preset RF field strength may be any two different preset RF field strengths. This application does not limit the specific values ​​of the first preset RF field strength and the second preset RF field strength.

[0031] When the RF field strength of the magnetic resonance imaging device is the second preset RF field strength, due to the significant RF field inhomogeneity of the magnetic resonance imaging device under high magnetic field strength, the actual RF field strength at each location in the scanned object generally deviates from the second preset RF field strength, or the actual RF field strength at some locations in the scanned object deviates from the second preset RF field strength. Based on this, the actual CEST signal strength at the first chemical shift may be different from the ideal CEST signal strength at the first chemical shift when the actual RF field strength at the corresponding location reaches the second preset RF field strength, and the actual CEST signal strength at the second chemical shift may be different from the ideal CEST signal strength at the second chemical shift when the actual RF field strength at the corresponding location reaches the second preset RF field strength. Therefore, the electronic device can execute step 102 and perform RF field inhomogeneity correction based on the data obtained in step 102 to achieve accurate measurement of the GluCEST signal strength.

[0032] In one embodiment, the electronic device can obtain a second relative spatial distribution diagram of the radio frequency field when the radio frequency field strength is a second preset radio frequency field strength. The second relative spatial distribution diagram includes the ratio of the second actual radio frequency field strength at each position in the scanned object to the second preset radio frequency field strength. Therefore, by multiplying the second preset radio frequency field strength by the second relative spatial distribution diagram, the second actual radio frequency field strength at each position in the scanned object can be obtained.

[0033] Optionally, the electronic device may acquire the first relative spatial distribution map and the second relative spatial distribution map of the radio frequency field by using a TurboFLASH imaging method or a dual flip angle gradient echo imaging method.

[0034] It should be understood that the first relative spatial distribution map and the second relative spatial distribution map are consistent with the imaging parameters such as imaging field of view, spatial resolution, shimming range, and layer thickness of the actual CEST signal intensity obtained in step 101 and step 102 .

[0035] In a possible implementation, for any position in the scanned object, a method for acquiring the third actual CEST signal strength and the fourth actual CEST signal strength at the position includes: When the radio frequency field intensity is a second preset radio frequency field intensity, acquiring a magnetic resonance signal intensity image of a third radio frequency pulse mark at a first chemical shift and a magnetic resonance signal intensity image of a fourth radio frequency pulse mark at a second chemical shift; determining a third actual CEST signal intensity from the third radio frequency pulse labeled magnetic resonance signal intensity image; A fourth actual CEST signal intensity is determined from the magnetic resonance signal intensity image of the fourth radio frequency pulse labeling.

[0036] The third radio frequency pulse-marked magnetic resonance signal intensity image includes the radio frequency pulse-marked magnetic resonance signal intensity at each location in the scanned object at the first chemical shift when the radio frequency field intensity is the second preset radio frequency field intensity. For any location in the scanned object, the radio frequency pulse-marked magnetic resonance signal intensity at the first chemical shift at that location in the third radio frequency pulse-marked magnetic resonance signal intensity image can be determined as the third actual CEST signal intensity.

[0037] The fourth radio frequency pulse-labeled magnetic resonance signal intensity image includes the radio frequency pulse-labeled magnetic resonance signal intensity at each location in the scanned object at the second chemical shift when the radio frequency field intensity is the second preset radio frequency field intensity. For any location in the scanned object, the radio frequency pulse-labeled magnetic resonance signal intensity at the second chemical shift in the fourth radio frequency pulse-labeled magnetic resonance signal intensity image can be determined as the fourth actual CEST signal intensity.

[0038] Step 103 : Determine a first ideal CEST signal intensity at a first chemical shift at a target RF field intensity at the corresponding position based on the first actual RF field intensity, the first actual CEST signal intensity, the second actual RF field intensity, and the third actual CEST signal intensity at the same position.

[0039] Optionally, the target RF field strength may be at least one of a first preset RF field strength and a second preset RF field strength, or may be a RF field strength different from the first preset RF field strength and the second preset RF field strength. By way of example and not limitation, the target RF field strength may be any RF field strength within the range of 2 μT to 5 μT, or at least one RF field strength.

[0040] For any position in the scanned object, the first ideal CEST signal intensity at the first chemical shift at the target radio frequency field intensity at the position may refer to the CEST signal intensity at the first chemical shift at the position when the radio frequency field intensity at the position is the target radio frequency field intensity or reaches the target radio frequency field intensity (i.e., the CEST signal intensity that can be achieved at the first chemical shift at the position when there is no radio frequency field inhomogeneity or the radio frequency field inhomogeneity is not considered).

[0041] As an example and not a limitation, the target RF field strength is 3.5 μT, but the actual RF field strength at a certain position in the scanned object is 2 μT. In this case, the actual CEST signal strength at the first chemical shift at this position is not the desired first ideal CEST signal strength (i.e., the CEST signal strength at the first chemical shift when the actual RF field strength at this position is 3.5 μT). The electronic device can correct the actual CEST signal strength at this position to the first ideal CEST signal strength through the above step 103.

[0042] In a possible implementation, step 103 includes: For any position in the scanned object, solving the coefficient of a first linear function of the inverse of the CEST signal intensity at the first chemical shift and the radio frequency field intensity based on the first actual radio frequency field intensity, the first actual CEST signal intensity, the second actual radio frequency field intensity, and the third actual CEST signal intensity at the position; When the coefficients of the first linear function are obtained, a first ideal CEST signal strength is determined based on the target radio frequency field strength and the first linear function.

[0043] Before executing step 103, the electronic device may construct a first linear function for each position in the scanned object (i.e., each position in the scanned object corresponds to a first linear function). In this case, the coefficients of the first linear function are unknown. Then, for any position in the scanned object, the coefficients of the first linear function corresponding to that position may be solved using the above implementation method. After solving for the coefficients of the first linear function, the target RF field strength may be substituted into the first linear function with known coefficients to obtain the first ideal CEST signal strength.

[0044] Step 104 : Determine a second ideal CEST signal intensity at a second chemical shift at a target RF field intensity at the corresponding position based on the first actual RF field intensity, the second actual CEST signal intensity, the second actual RF field intensity, and the fourth actual CEST signal intensity at the same position.

[0045] For any position in the scanned object, the second ideal CEST signal intensity at the second chemical shift at the target radio frequency field intensity at the position may refer to the CEST signal intensity at the second chemical shift at the position when the radio frequency field intensity at the position is the target radio frequency field intensity or reaches the target radio frequency field intensity (i.e., the CEST signal intensity that can be achieved at the second chemical shift at the position when there is no radio frequency field inhomogeneity or the inhomogeneity of the radio frequency field is not considered).

[0046] As an example and not a limitation, if the target RF field strength is 3.5 μT, but the actual RF field strength at a certain position in the scanned object is 2 μT, then the actual CEST signal strength at the second chemical shift at this position is not the desired second ideal CEST signal strength (i.e., the CEST signal strength at the second chemical shift when the actual RF field strength at this position is 3.5 μT). The electronic device can correct the actual CEST signal strength at this position to the second ideal CEST signal strength through the above step 103.

[0047] Step 105 : Determine the GluCEST signal strength at the corresponding position under the target radio frequency field strength based on the first ideal CEST signal strength and the second ideal CEST signal strength at the same position under the target radio frequency field strength.

[0048] In a possible implementation, step 105 includes: For any position in the scanned object, determining the difference between the second ideal CEST signal strength and the first ideal CEST signal strength at the position under the target radio frequency field strength; The ratio of the difference value to the second ideal CEST signal intensity is determined as the GluCEST signal intensity at the position under the target radio frequency field intensity; Alternatively, the ratio of the difference value to the magnetic resonance signal intensity at the location without radio frequency pulse marking is determined as the GluCEST signal intensity at the location under the target radio frequency field intensity.

[0049] For any location in the scanned object, the first ideal CEST signal intensity includes the water molecule signal attenuation caused by glutamate, while the second ideal CEST signal intensity does not. Based on this, the first ideal CEST signal intensity is subtracted from the second ideal CEST signal intensity, and the difference is divided by the magnetic resonance signal intensity without RF pulse labeling or the second ideal CEST signal intensity to obtain the GluCEST signal intensity, thereby achieving accurate measurement of the GluCEST signal intensity.

[0050] This embodiment has been tested in brain experiments and has been confirmed to be able to correct radio frequency field inhomogeneity and achieve accurate measurement of GluCEST signal intensity.

[0051] In the brain realization test, the preset RF field intensity (i.e. Figure 2 in ) are 3.5μT, 4μT (i.e. 4.0μT) and 4.5μT, saturation time is 800ms, repetition time is 5s, chemical shift is ±3.3ppm, ±3ppm and ±2.7ppm. The distribution of brain GluCEST signal intensity corresponding to 3.5μT, 4μT and 4.5μT is shown in the figure. Figure 2 As shown in Figure 3, white matter regions were segmented from MRI signal intensity images without radiofrequency pulse labeling using a thresholding method. Three regions of interest (ROIs) were defined based on the range of variation of the actual radiofrequency field intensity within the white matter region compared to 100% (i.e., the preset radiofrequency field intensity): ROI1 (the region with an absolute variation of less than 10%), ROI2 (the region with an absolute variation between 10% and 20%), and ROI3 (the region with an absolute variation greater than 20%). The average GluCEST signal intensity at each location within the region with an absolute variation of less than 2% was selected as the reference intensity. When the preset RF field intensity was 3.5 μT, the reference intensity was 8.23±1.12%, and the GluCEST signal intensities of the three ROIs were 7.54±0.88%, 5.87±0.82% and 3.48±0.44%, respectively. When the preset RF field intensity was 4 μT, the reference intensity was 10.03±1.28%, and the GluCEST signal intensities of the three ROIs were 9.37±1.01%, 7.92±0.96% and 5.72±0.16%, respectively. When the preset RF field intensity was 4.5 μT, the reference intensity was 11.50±1.44%, and the GluCEST signal intensities of the three ROIs were 11.08±1.10%, 9.94±0.97% and 7.77±0.42%, respectively. It can be seen that the GluCEST signal intensity of different ROIs is significantly different from the reference intensity, confirming that the inhomogeneity of the radiofrequency field affects the accuracy of the measurement of the GluCEST signal intensity. Figure 2 0 to 18 represents the range of variation of the actual RF field strength compared to 100%, expressed in percentage. Figure 2 The 18 in represents 18%. Figure 2 It can be seen that when the preset radio frequency field intensities are 3.5μT, 4μT and 4.5μT, the spatial distribution of GluCEST signal intensity in the same tissue in the brain shows obvious differences due to the inhomogeneity of the radio frequency field.

[0052] Based on the constructed first linear function 1 / Z(+ 3ppm) = C0 + C1 *B1 and the second linear function 1 / Z(-3ppm) = C2 + C3 *B1, * is the multiplication sign, Z(+ 3ppm) is the CEST signal intensity at the first chemical shift, Z(- 3ppm) is the CEST signal intensity at the second chemical shift, and B1 in the first and second linear functions is the radio frequency field intensity. The coefficients such as C0 and C1 in the first linear function and the coefficients such as C2 and C3 in the second linear function can be obtained from the actual radio frequency field intensity and the corresponding actual CEST signal intensity, and then the ideal CEST signal intensity at + 3ppm and - 3ppm can be obtained, thereby solving the influence of radio frequency field inhomogeneity on the measurement of GluCEST signal intensity. The two radio frequency field intensities of 4μT and 4.5μT are used as the preset radio frequency field intensity and the target radio frequency field intensity for the two-point radio frequency field correction, and the three radio frequency field intensities of 3.5μT, 4μT and 4.5μT are used as the preset radio frequency field intensity and the target radio frequency field intensity for the three-point radio frequency field correction. As shown Figure 3 The example diagram of the radio frequency field correction result based on the first linear function is shown in FIG. Figure 4 The figure shows an example of the RF field correction result based on the second linear function.

[0053] For any location in the white matter region, Figure 3 The abscissa of A1 in the figure represents the actual radio frequency field intensity at the position when the radio frequency field intensity is 3.5 μT, and the ordinate represents the actual radio frequency field intensity of the CEST signal at the first chemical shift at the position under the actual radio frequency field intensity; Figure 3 The abscissa of A2 in the figure represents the actual radio frequency field intensity at the position when the radio frequency field intensity is 4 μT, and the ordinate represents the actual CEST signal intensity at the first chemical shift at the position under the actual radio frequency field intensity; Figure 3 The horizontal axis of A3 in the figure represents the target radio frequency field intensity of 3.5 μT at the position, and the vertical axis represents the ideal CEST signal intensity at the first chemical shift at 3.5 μT at the position; Figure 3 The horizontal axis of A4 in the figure represents the actual radio frequency field intensity at the position when the radio frequency field intensity is 4.5 μT, and the vertical axis represents the actual CEST signal intensity at the first chemical shift at the position under the actual radio frequency field intensity; Figure 3 The horizontal axis of A5 in the figure represents the target radio frequency field intensity of 4 μT at this position, and the vertical axis represents the ideal CEST signal intensity at the first chemical shift under 4 μT at this position; Figure 3 The abscissa of A6 in FIG. 5 represents the target radio frequency field intensity of 4.5 μT at the position, and the ordinate represents the ideal CEST signal intensity at the first chemical shift under 4.5 μT at the position.

[0054] It should be noted that Figure 3 The yellow line in the figure coincides with the green line. The circle on the yellow line describes A5 during two-point RF field calibration, and the circle on the green line describes A5 during three-point RF calibration. Figure 3 The cyan line in the figure overlaps with the blue line. The circle on the cyan line is used to describe A6 during two-point RF field calibration, and the circle on the blue line is used to describe A6 during three-point RF calibration. Figure 3 The black dotted line in represents the first linear function fitted by A2 and A4, and the black solid line represents the first linear function fitted based on A1, A2, and A4.

[0055] For any location in the white matter region, Figure 4 The horizontal axis of D1 in the figure represents the actual radio frequency field intensity at the position when the radio frequency field intensity is 3.5 μT, and the vertical axis represents the actual radio frequency field intensity of the CEST signal at the second chemical shift at the position under the actual radio frequency field intensity; Figure 4 The horizontal axis of D2 in the figure represents the actual radio frequency field intensity at the position when the radio frequency field intensity is 4 μT, and the vertical axis represents the actual CEST signal intensity at the second chemical shift at the position under the actual radio frequency field intensity; Figure 4 The horizontal axis of D3 in the figure indicates that the target radio frequency field intensity at the position is 3.5 μT, and the vertical axis indicates the ideal CEST signal intensity at the second chemical shift at 3.5 μT. Figure 4 The horizontal axis of D4 in the figure represents the actual radio frequency field intensity at the position when the radio frequency field intensity is 4.5 μT, and the vertical axis represents the actual CEST signal intensity at the second chemical shift at the position under the actual radio frequency field intensity; Figure 4 The horizontal axis of D5 in the figure represents the target radio frequency field intensity of 4 μT at this position, and the vertical axis represents the ideal CEST signal intensity at the second chemical shift under 4 μT at this position; Figure 4 The horizontal axis of D6 in FIG. 5 represents the target radio frequency field intensity of 4.5 μT at the position, and the vertical axis represents the ideal CEST signal intensity at the second chemical shift under 4.5 μT at the position.

[0056] It should be noted that Figure 4 The yellow line in the figure coincides with the green line. The circle on the yellow line describes D5 for two-point RF field calibration, and the circle on the green line describes D5 for three-point RF calibration. Figure 4 The cyan line in the figure overlaps with the blue line. The circle on the cyan line is used to describe D6 during two-point RF field calibration, and the circle on the blue line is used to describe D6 during three-point RF calibration. Figure 4The black dotted line in represents the second linear function fitted by D2 and D4, and the black solid line represents the second linear function fitted based on D1, D2, and D4.

[0057] Depend on Figure 3 and Figure 4 It can be seen that the results obtained by the two-point RF field correction are close to those obtained by the three-point RF field correction, which proves that the RF field correction method proposed in this embodiment has good stability and can correct the RF field based on the magnetic resonance data of two preset RF field intensities.

[0058] After the radio frequency field inhomogeneity correction is implemented according to this embodiment, the distribution of the GluCEST signal intensity in the brain is as follows: Figure 5 As shown, Figure 5 The 3.5μT, 4μT and 4.5μT are preset RF field intensities. These three preset RF field intensities are used as target RF field intensities to facilitate the comparison of results before and after calibration. Figure 5 in represents two-point RF field correction, "" represents three-point radiofrequency field correction. When the preset radiofrequency field intensity was 3.5 μT, the GluCEST signal intensities in the three ROIs after two-point radiofrequency field correction were 8.34 ± 0.91%, 8.61 ± 0.92%, and 8.69 ± 0.93%, respectively. The GluCEST signal intensities in the three ROIs after three-point radiofrequency field correction were 8.27 ± 0.92%, 8.52 ± 0.95%, and 8.63 ± 0.96%, respectively. When the preset radiofrequency field intensity was 4 μT, the GluCEST signal intensities in the three ROIs after two-point radiofrequency field correction were 10.24 ± 1.05%, 10.49 ± 1.01%, and 10.39 ± 1.01%, respectively. The GluCEST signal intensities in the three ROIs after three-point radiofrequency field correction were 10.18 ± 1.05%, 10.42 ± 1.02%, and 10.34 ± 1.03%, respectively. When the preset RF field strength was 4.5 μT, the GluCEST signal intensities of the three ROIs corrected with two-point RF field correction were 11.65 ± 1.17%, 11.91 ± 1.09%, and 11.69 ± 1.10%, respectively; the GluCEST signal intensities of the three ROIs corrected with three-point RF field correction were 11.59 ± 1.17%, 11.84 ± 1.10%, and 11.65 ± 1.11%, respectively. After RF field correction, at preset RF field strengths of 3.5 μT, 4 μT, and 4.5 μT, the difference between the GluCEST signal intensities of the three ROIs and the reference intensity was much smaller than before RF field correction. This shows that the RF field correction scheme provided in this embodiment effectively improves the impact of RF field inhomogeneity on the measurement of GluCEST signal strength.

[0059] Depend on Figure 5It can be seen that the signals of the same tissue in the brain are more uniform than before correction, and the correction results obtained by two-point RF field correction and three-point RF field correction under three target RF field intensities are similar, confirming that the RF field correction method provided in this embodiment has good stability and can correct RF field inhomogeneity based on magnetic resonance data of two different preset RF field intensities.

[0060] In an embodiment of the present application, by obtaining the actual radio frequency field intensity at each position in the scanned object under two preset radio frequency field intensities, the actual CEST signal intensity at the chemical shift of glutamate, and the actual CEST signal intensity at the chemical shift of glutamate on the opposite side of the water molecule, and based on the actual radio frequency field intensity at the two preset radio frequency field intensities and the actual CEST signal intensity at the chemical shift of glutamate at the same position, the CEST signal intensity at the chemical shift of glutamate at the target radio frequency field intensity can be corrected, thereby obtaining the ideal CEST signal intensity at the chemical shift of glutamate at the target radio frequency field intensity, thereby achieving correction of radio frequency field inhomogeneity. The correction is based on the actual RF field intensity at the same position under two preset RF field intensities and the actual CEST signal intensity at the chemical shift of glutamate relative to the opposite side of the water molecule. The CEST signal intensity at the chemical shift of glutamate relative to the opposite side of the water molecule at the target RF field intensity at this position can be corrected, thereby obtaining the ideal CEST signal intensity at the chemical shift of glutamate relative to the opposite side of the water molecule at this position under the target RF field intensity, thereby realizing the correction of RF field uniformity. Based on the above two ideal CEST signal intensities at the same position under the target RF field intensity, the GluCEST signal intensity at this position under the target RF field intensity can be accurately measured.

[0061] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0062] Corresponding to the radio frequency field non-uniformity correction method described in the above embodiment, Figure 6 A schematic structural diagram of a radio frequency field non-uniformity correction device provided in an embodiment of the present application is shown. For ease of explanation, only the portion related to the embodiment of the present application is shown.

[0063] Reference Figure 6 , the device comprises: A first acquisition module 601 is configured to acquire, when the radio frequency field intensity of the radio frequency field is a first preset radio frequency field intensity, a first actual chemical exchange saturation transfer (CEST) signal intensity at a first chemical shift, and a second actual CEST signal intensity at a second chemical shift at each position in the scanned object, wherein the first chemical shift is the chemical shift of glutamate, and the second chemical shift is the chemical shift of the glutamate relative to the opposite side of a water molecule; a second acquisition module 602, configured to acquire, when the radio frequency field intensity of the radio frequency field is a second preset radio frequency field intensity, a second actual radio frequency field intensity at each position in the scanned object, a third actual CEST signal intensity at the first chemical shift, and a fourth actual CEST signal intensity at the second chemical shift, wherein the second preset radio frequency field intensity is different from the first preset radio frequency field intensity; A first determining module 603 is configured to determine a first ideal CEST signal intensity at the first chemical shift under a target RF field intensity at a corresponding position based on the first actual RF field intensity, the first actual CEST signal intensity, the second actual RF field intensity, and the third actual CEST signal intensity at the same position; a second determining module 604, configured to determine a second ideal CEST signal intensity at the second chemical shift at the corresponding position under the target RF field intensity based on the first actual RF field intensity, the second actual CEST signal intensity, the second actual RF field intensity, and the fourth actual CEST signal intensity at the same position; The third determining module 605 is configured to determine the glutamate GluCEST signal intensity at the corresponding position under the target radio frequency field intensity based on the first ideal CEST signal intensity and the second ideal CEST signal intensity at the same position under the target radio frequency field intensity.

[0064] Optionally, the first determining module 603 is specifically configured to: For any position in the scanned object, solving for a coefficient of a first linear function of the reciprocal of the CEST signal intensity at the first chemical shift and the radio frequency field intensity at the position based on the first actual radio frequency field intensity, the first actual CEST signal intensity, the second actual radio frequency field intensity, and the third actual CEST signal intensity at the position; When the coefficients of the first linear function are obtained, the first ideal CEST signal strength is determined based on the target radio frequency field strength and the first linear function.

[0065] Optionally, the second determining module 604 is specifically configured to: For any position in the scanned object, solving for a coefficient of a second linear function of the reciprocal of the CEST signal intensity at the second chemical shift and the radio frequency field intensity at the position based on the first actual radio frequency field intensity, the second actual CEST signal intensity, the second actual radio frequency field intensity, and the fourth actual CEST signal intensity at the position; When the coefficients of the second linear function are obtained, the second ideal CEST signal strength is determined based on the target radio frequency field strength and the second linear function.

[0066] Optionally, the third determining module 605 is specifically configured to: For any position in the scan object, determining a difference between the second ideal CEST signal strength and the first ideal CEST signal strength at the position under the target radio frequency field strength; determining a ratio of the difference to the second ideal CEST signal intensity as the GluCEST signal intensity at the position under the target radio frequency field intensity; Alternatively, the ratio of the difference to the magnetic resonance signal intensity at the position without radio frequency pulse marking is determined as the GluCEST signal intensity at the position under the target radio frequency field intensity.

[0067] Optionally, the first obtaining module 601 is specifically configured to: When the radio frequency field intensity of the radio frequency field is the first preset radio frequency field intensity, acquiring a magnetic resonance signal intensity image of a first radio frequency pulse mark at the first chemical shift and a magnetic resonance signal intensity image of a second radio frequency pulse mark at the second chemical shift; determining the first actual CEST signal intensity from the magnetic resonance signal intensity image of the first radio frequency pulse labeling; The second actual CEST signal intensity is determined from the magnetic resonance signal intensity image of the second radio frequency pulse labeling.

[0068] Optionally, the second obtaining module 602 is specifically configured to: When the radio frequency field intensity of the radio frequency field is the second preset radio frequency field intensity, acquiring a magnetic resonance signal intensity image of a third radio frequency pulse mark at the first chemical shift and a magnetic resonance signal intensity image of a fourth radio frequency pulse mark at the second chemical shift; determining the third actual CEST signal intensity from the magnetic resonance signal intensity image of the third radio frequency pulse labeling; The fourth actual CEST signal intensity is determined from the magnetic resonance signal intensity image of the fourth radio frequency pulse labeling.

[0069] It should be noted that the information interaction, execution process, etc. between the above-mentioned devices / units are based on the same concept as the method embodiment of this application. Their specific functions and technical effects can be found in the method embodiment section and will not be repeated here.

[0070] Figure 7 This is a schematic diagram of the structure of the electronic device provided in the embodiment of the present application. Figure 7 As shown, the electronic device 7 of this embodiment includes: at least one processor 70 ( Figure 7 Only one is shown in the figure), a memory 71, and a computer program 72 stored in the memory 71 and executable on the at least one processor 70, wherein the processor 70 implements the steps of any of the above-mentioned method embodiments when executing the computer program 72.

[0071] The electronic device may include, but is not limited to, a processor 70 and a memory 71. Those skilled in the art will understand that Figure 7 It is only an example of the electronic device 7 and does not constitute a limitation on the electronic device 7. It may include more or fewer components than shown in the figure, or a combination of certain components, or different components. For example, it may also include input and output devices, network access devices, etc.

[0072] The processor 70 may be a central processing unit (CPU), or other general-purpose processors, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. A general-purpose processor may be a microprocessor or any conventional processor.

[0073] In some embodiments, the memory 71 may be an internal storage unit of the electronic device 7, such as a hard drive or memory of the electronic device 7. In other embodiments, the memory 71 may also be an external storage device of the electronic device 7, such as a plug-in hard drive, a Smart Media Card (SMC), a Secure Digital (SD) card, a flash card, etc. equipped on the electronic device 7. Furthermore, the memory 71 may include both an internal storage unit of the electronic device 7 and an external storage device. The memory 71 is used to store an operating system, application programs, a boot loader, data, and other programs, such as the program code of the computer program. The memory 71 may also be used to temporarily store data that has been output or is about to be output.

[0074] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In actual applications, the above-mentioned functions can be distributed and completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here.

[0075] If the integrated unit is implemented as a software functional unit and sold or used as a standalone product, it can be stored in a computer-readable storage medium. Based on this understanding, the present application implements all or part of the process steps in the above-mentioned method embodiments by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium. When executed by a processor, the computer program can implement the steps of each of the above-mentioned method embodiments. The computer program includes computer program code, which can be in source code form, object code form, executable file, or some intermediate form. The computer-readable medium can include at least: any entity or device capable of carrying computer program code to a device / electronic device, a recording medium, computer memory, read-only memory (ROM), random access memory (RAM), an electrical carrier signal, a telecommunications signal, and a software distribution medium. Examples include a USB flash drive, a removable hard drive, a magnetic disk, or an optical disk.

[0076] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant description of other embodiments.

[0077] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0078] In the embodiments provided in the present application, it should be understood that the disclosed devices / electronic devices and methods can be implemented in other ways. For example, the device / electronic device embodiments described above are merely schematic. For example, the division of the modules or units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0079] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0080] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included in the scope of protection of the present application.

Claims

1. A method for correcting radio frequency field inhomogeneity, characterized in that: include: When the radio frequency field intensity is a first preset radio frequency field intensity, obtaining a first actual radio frequency field intensity at each position in the scanned object, a first actual chemical exchange saturation transfer (CEST) signal intensity at a first chemical shift, and a second actual CEST signal intensity at a second chemical shift, wherein the first chemical shift is the chemical shift of glutamate, and the second chemical shift is the chemical shift of the glutamate relative to the opposite side of a water molecule; acquiring, when the radio frequency field intensity is a second preset radio frequency field intensity, a second actual radio frequency field intensity at each position in the scanned object, a third actual CEST signal intensity at the first chemical shift, and a fourth actual CEST signal intensity at the second chemical shift, wherein the second preset radio frequency field intensity is different from the first preset radio frequency field intensity; determining a first ideal CEST signal intensity at the first chemical shift at the corresponding position under a target radio frequency field intensity based on the first actual radio frequency field intensity, the first actual CEST signal intensity, the second actual radio frequency field intensity, and the third actual CEST signal intensity at the same position; determining a second ideal CEST signal intensity at the second chemical shift at the corresponding position under the target radio frequency field intensity based on the first actual radio frequency field intensity, the second actual CEST signal intensity, the second actual radio frequency field intensity, and the fourth actual CEST signal intensity at the same position; Based on the first ideal CEST signal intensity and the second ideal CEST signal intensity at the same position at the target radio frequency field intensity, the glutamate GluCEST signal intensity at the corresponding position at the target radio frequency field intensity is determined.

2. The radio frequency field non-uniformity correction method according to claim 1, characterized in that: The determining, based on the first actual radio frequency field intensity, the first actual CEST signal intensity, the second actual radio frequency field intensity, and the third actual CEST signal intensity at the same position, a first ideal CEST signal intensity at the first chemical shift under the target radio frequency field intensity at the corresponding position includes: For any position in the scanned object, solving for a coefficient of a first linear function of the reciprocal of the CEST signal intensity at the first chemical shift and the radio frequency field intensity at the position based on the first actual radio frequency field intensity, the first actual CEST signal intensity, the second actual radio frequency field intensity, and the third actual CEST signal intensity at the position; When the coefficients of the first linear function are obtained, the first ideal CEST signal strength is determined based on the target radio frequency field strength and the first linear function.

3. The radio frequency field non-uniformity correction method according to claim 1, characterized in that: The determining, based on the first actual radio frequency field intensity, the second actual CEST signal intensity, the second actual radio frequency field intensity, and the fourth actual CEST signal intensity at the same position, a second ideal CEST signal intensity at the second chemical shift under the target radio frequency field intensity at the corresponding position includes: For any position in the scanned object, solving for a coefficient of a second linear function of the reciprocal of the CEST signal intensity at the second chemical shift and the radio frequency field intensity at the position based on the first actual radio frequency field intensity, the second actual CEST signal intensity, the second actual radio frequency field intensity, and the fourth actual CEST signal intensity at the position; When the coefficients of the second linear function are obtained, the second ideal CEST signal strength is determined based on the target radio frequency field strength and the second linear function.

4. The radio frequency field non-uniformity correction method according to any one of claims 1 to 3, characterized in that: The determining, based on the first ideal CEST signal strength and the second ideal CEST signal strength at the same position at the target radio frequency field strength, the glutamate GluCEST signal strength at the corresponding position at the target radio frequency field strength includes: For any position in the scan object, determining a difference between the second ideal CEST signal strength and the first ideal CEST signal strength at the position under the target radio frequency field strength; determining a ratio of the difference to the second ideal CEST signal intensity as the GluCEST signal intensity at the position under the target radio frequency field intensity; Alternatively, the ratio of the difference to the magnetic resonance signal intensity at the position without radio frequency pulse marking is determined as the GluCEST signal intensity at the position under the target radio frequency field intensity.

5. The radio frequency field non-uniformity correction method according to any one of claims 1 to 3, characterized in that: For any position in the scanned object, a method for acquiring the first actual CEST signal strength and the second actual CEST signal strength at the position includes: When the radio frequency field intensity is the first preset radio frequency field intensity, acquiring a magnetic resonance signal intensity image of a first radio frequency pulse mark at the first chemical shift and a magnetic resonance signal intensity image of a second radio frequency pulse mark at the second chemical shift; determining the first actual CEST signal intensity from the magnetic resonance signal intensity image of the first radio frequency pulse labeling; The second actual CEST signal intensity is determined from the magnetic resonance signal intensity image of the second radio frequency pulse labeling.

6. The radio frequency field non-uniformity correction method according to any one of claims 1 to 3, characterized in that: For any position in the scanned object, a method for acquiring the third actual CEST signal strength and the fourth actual CEST signal strength at the position includes: When the radio frequency field intensity is the second preset radio frequency field intensity, acquiring a magnetic resonance signal intensity image of a third radio frequency pulse mark at the first chemical shift and a magnetic resonance signal intensity image of a fourth radio frequency pulse mark at the second chemical shift; determining the third actual CEST signal intensity from the magnetic resonance signal intensity image of the third radio frequency pulse labeling; The fourth actual CEST signal intensity is determined from the magnetic resonance signal intensity image of the fourth radio frequency pulse labeling.

7. A radio frequency field inhomogeneity correction device, characterized in that: include: a first acquisition module, configured to acquire, when the radio frequency field intensity is a first preset radio frequency field intensity, a first actual chemical exchange saturation transfer (CEST) signal intensity at a first chemical shift, and a second actual CEST signal intensity at a second chemical shift at each position in the scanned object, wherein the first chemical shift is the chemical shift of glutamate, and the second chemical shift is the chemical shift of the glutamate relative to the opposite side of a water molecule; a second acquisition module, configured to acquire, when the radio frequency field intensity is a second preset radio frequency field intensity, a second actual radio frequency field intensity at each position in the scanned object, a third actual CEST signal intensity at the first chemical shift, and a fourth actual CEST signal intensity at the second chemical shift; a first determining module, configured to determine a first ideal CEST signal intensity at the first chemical shift at the corresponding position under a target radio frequency field intensity based on the first actual radio frequency field intensity, the first actual CEST signal intensity, the second actual radio frequency field intensity, and the third actual CEST signal intensity at the same position; a second determining module, configured to determine a second ideal CEST signal intensity at the second chemical shift at the corresponding position under the target radio frequency field intensity based on the first actual radio frequency field intensity, the second actual CEST signal intensity, the second actual radio frequency field intensity, and the fourth actual CEST signal intensity at the same position; The third determination module is configured to determine the glutamate GluCEST signal intensity at the corresponding position under the target radio frequency field intensity based on the first ideal CEST signal intensity and the second ideal CEST signal intensity at the same position under the target radio frequency field intensity.

8. The radio frequency field non-uniformity correction device according to claim 7, characterized in that: The first determining module is specifically configured to: For any position in the scanned object, solving for a coefficient of a first linear function of the reciprocal of the CEST signal intensity at the first chemical shift and the radio frequency field intensity at the position based on the first actual radio frequency field intensity, the first actual CEST signal intensity, the second actual radio frequency field intensity, and the third actual CEST signal intensity at the position; When the coefficients of the first linear function are obtained, the first ideal CEST signal strength is determined based on the target radio frequency field strength and the first linear function.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the electronic device implements the radio frequency field non-uniformity correction method according to any one of claims 1 to 6.

10. A computer program product, characterized in that The invention comprises a computer program, which enables the radio frequency field inhomogeneity correction method according to any one of claims 1 to 6 to be performed when the computer program is executed.

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