Method, apparatus, computer device, and medium for determining center frequency of radio frequency system

Abstract

The present application relates to a method, apparatus, computer device, storage medium, and program product for determining the center frequency of a radio frequency system. The method includes collecting a first magnetic resonance signal and a second magnetic resonance signal; determining a first frequency spectrum corresponding to the first magnetic resonance signal and a second frequency spectrum corresponding to the second magnetic resonance signal; determining a relative relaxation frequency spectrum based on the first frequency spectrum and the second frequency spectrum; determining a characteristic frequency of a target imaging nuclide in a target tissue by analyzing the relative relaxation frequency spectrum, and determining the center frequency of the radio frequency system according to the characteristic frequency. By using the method for determining the center frequency of the radio frequency system provided by the present application, a more accurate center frequency can be obtained.

Description

Technical Field

[0001] This application relates to the field of magnetic resonance imaging technology, and particularly to a method, device, computer device, and storage medium for determining the center frequency of a radio frequency system. Background Art

[0002] During the imaging process of clinical magnetic resonance equipment, the center frequency of the radio frequency system in the magnetic resonance equipment is determined through the spectral information corresponding to the magnetic resonance signal, so that the center frequency of the radio frequency system is aligned with the Larmor frequency of the imaging nuclide in the target tissue, thereby achieving the best imaging effect.

[0003] In traditional technologies, the center frequency of the imaging nuclide in the target tissue is determined by analyzing the spectral line characteristics of the collected magnetic resonance signals, that is, by using a single spectral line analysis method. However, in the face of the complex and changeable scenarios of clinical scans, the above single spectral line analysis method is difficult to adapt to, and there is a problem that the center frequency determined by this analysis is inaccurate. Summary of the Invention

[0004] Based on this, it is necessary to provide a method, device, computer device, storage medium, and program product for determining the center frequency of a radio frequency system in view of the above technical problems.

[0005] In a first aspect, an embodiment of the present application provides a method for determining the center frequency of a radio frequency system, including:

[0006] Collect a first magnetic resonance signal and a second magnetic resonance signal. The first magnetic resonance signal is obtained by a first pulse sequence, and the second magnetic resonance signal is obtained by a second pulse sequence. The first pulse sequence and the second pulse sequence are arranged adjacent to each other;

[0007] Determine a first spectrum corresponding to the first magnetic resonance signal and a second spectrum corresponding to the second magnetic resonance signal;

[0008] Determine a relative relaxation spectrum according to the first spectrum and the second spectrum;

[0009] Determine the characteristic frequency of the target imaging nuclide in the target tissue by analyzing the relative relaxation spectrum, and determine the center frequency of the radio frequency system according to the characteristic frequency.

[0010] In one embodiment, a radio frequency pulse is applied between the first pulse sequence and the second pulse sequence; the radio frequency pulse has a preset flip angle.

[0011] In one embodiment, a dephasing gradient is applied within a preset time after the radio frequency pulse.

[0012] In one embodiment, determining a relative relaxation spectrum according to the first spectrum and the second spectrum includes:

[0013] Determine the proportional relationship between the first spectrum and the second spectrum, and determine the relative relaxation spectrum according to the proportional relationship;

[0014] Alternatively, calculate the difference between the first spectrum and the second spectrum, and determine the relative relaxation spectrum according to the difference.

[0015] In one embodiment, determining the characteristic frequency of the target imaging radionuclide in the target tissue by analyzing the relative relaxation spectrum includes:

[0016] By analyzing the relative relaxation spectrum, determine the correspondence between different tissues and frequencies;

[0017] According to the correspondence between different tissues and frequencies, determine the frequency of the target imaging radionuclide in the target tissue;

[0018] Determine the characteristic frequency according to the frequency of the target imaging radionuclide in the target tissue.

[0019] In one embodiment, determining the correspondence between different tissues and frequencies by analyzing the relative relaxation spectrum includes:

[0020] According to the relative relaxation spectrum, obtain the amplitude intensity change of different frequencies;

[0021] According to the amplitude intensity change of different frequencies and the preset intensity change conditions of different tissues, determine the correspondence between different tissues and frequencies.

[0022] In one embodiment, determining the characteristic frequency according to the frequency of the target imaging radionuclide in the target tissue includes:

[0023] Obtain the spectrum of the target imaging radionuclide in the target tissue;

[0024] Calculate the maximum value of the amplitude intensity in the spectrum, and use the frequency corresponding to the maximum value of the amplitude intensity as the characteristic frequency.

[0025] In one embodiment, the characteristic frequency determined according to the frequency of the target imaging radionuclide in the target tissue includes:

[0026] Perform fitting processing on the frequency of the target imaging radionuclide in the target tissue to obtain the characteristic frequency.

[0027] In a second aspect, an embodiment of the present application provides a device for determining the center frequency of a radio frequency system, including:

[0028] An acquisition module, configured to acquire a first magnetic resonance signal and a second magnetic resonance signal. The first magnetic resonance signal is obtained by a first pulse sequence, and the second magnetic resonance signal is obtained by a second pulse sequence. The first pulse sequence and the second pulse sequence are arranged adjacent to each other;

[0029] A first determination module, configured to determine a first spectrum corresponding to a first magnetic resonance signal and a second spectrum corresponding to a second magnetic resonance signal;

[0030] A second determination module, configured to determine a relative relaxation spectrum according to the first spectrum and the second spectrum;

[0031] A third determination module, configured to determine a characteristic frequency of a target imaging nuclide in a target tissue by analyzing frequencies of different tissues in the relative relaxation spectrum, and determine a center frequency of a radio frequency system according to the characteristic frequency.

[0032] In a third aspect, an embodiment of the present application provides a computer device, including a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, the steps of the radio frequency system center frequency determination method provided in the above embodiment are implemented.

[0033] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the radio frequency system center frequency determination method provided in the above embodiment are implemented.

[0034] In a fifth aspect, an embodiment of the present application further provides a computer program product, including a computer program. When the computer program is executed by a processor, the steps of the radio frequency system center frequency determination method provided in the above embodiment are implemented.

[0035] An embodiment of the present application provides a radio frequency system center frequency determination method, apparatus, computer device, storage medium, and program product. The radio frequency system center frequency determination method collects a first magnetic resonance signal and a second magnetic resonance signal, determines a first spectrum corresponding to the first magnetic resonance signal and a second spectrum corresponding to the second magnetic resonance signal; determines a relative relaxation spectrum according to the first spectrum and the second spectrum; determines a characteristic frequency of a target imaging nuclide in a target tissue by analyzing the relative relaxation spectrum, and determines a center frequency of a radio frequency system according to the characteristic frequency. The radio frequency system center frequency determination method provided in the embodiment of the present application takes into account the influence of relaxation on the magnetic resonance signal, that is, the second spectrum corresponding to the second magnetic resonance signal is affected by relaxation. By analyzing the difference (relative relaxation spectrum) between the second spectrum corresponding to the second magnetic resonance signal and the first spectrum corresponding to the first magnetic resonance signal, the frequency of the target imaging nuclide in the target tissue can be found more accurately, so as to improve the accuracy of determining the characteristic frequency of the target imaging nuclide in the target tissue. Furthermore, the characteristic frequency can be used to accurately calibrate the radio frequency system in the magnetic resonance device to obtain a more accurate radio frequency system center frequency. Description of the Drawings

[0036] To more clearly illustrate the technical solutions in the embodiments of the present application or in the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0037] Figure 1 An application environment diagram of a method for determining the center frequency of a radio frequency system provided for an embodiment;

[0038] Figure 2 A schematic flow chart of the steps of a method for determining the center frequency of a radio frequency system provided for an embodiment;

[0039] Figure 3 A schematic diagram of a first pulse sequence, a radio frequency pulse, a dephasing gradient, a second pulse sequence, a first magnetic resonance signal, and a second magnetic resonance signal provided for an embodiment;

[0040] Figure 4 A schematic diagram of a first pulse sequence, a radio frequency pulse, a second pulse sequence, a first magnetic resonance signal, and a second magnetic resonance signal provided for another embodiment;

[0041] Figure 5 A schematic flow chart of the steps of a method for determining the center frequency of a radio frequency system provided for another embodiment;

[0042] Figure 6 A schematic flow chart of the steps of a method for determining the center frequency of a radio frequency system provided for another embodiment;

[0043] Figure 7 A schematic flow chart of the steps of a method for determining the center frequency of a radio frequency system provided for another embodiment;

[0044] Figure 8 A schematic structural diagram of a device for determining the center frequency of a radio frequency system provided for an embodiment;

[0045] Figure 9 A schematic structural diagram of a computer device provided for an embodiment. Detailed implementation manners

[0046] To make the above objects, features, and advantages of the present application more clearly understandable, the following will provide a detailed description of the specific implementation manners of the present application with reference to the accompanying drawings. Many specific details are set forth in the following description to fully understand the present application. However, the present application can be implemented in many other ways different from those described herein. Those skilled in the art can make similar improvements without departing from the spirit of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

[0047] The serial numbers assigned to components in this document itself, such as "first", "second", etc., are only used to distinguish the described objects and do not have any sequential or technical meaning.

[0048] The method for determining the center frequency of the radio frequency system provided by the embodiment of the present application can be applied to, for example, Figure 1 the application environment shown in the figure. This application environment includes a terminal 100 and a magnetic resonance device 200. Among them, the terminal 100 can communicate with the magnetic resonance device 200 through a network. The terminal 100 can be, but is not limited to, various personal computers, laptop computers, and tablet computers. The specific type of the magnetic resonance device 200 is not limited in this embodiment.

[0049] Please refer to Figure 2 , an embodiment of the present application provides a method for determining the center frequency of a radio frequency system. Taking the terminal in Figure 1 as an example, the method includes the following steps:

[0050] Step 200: Collect a first magnetic resonance signal and a second magnetic resonance signal. The first magnetic resonance signal is obtained from a first pulse sequence, and the second magnetic resonance signal is obtained from a second pulse sequence. The first pulse sequence and the second pulse sequence are arranged adjacent to each other.

[0051] The setting of relevant parameters such as radio frequency pulses, gradient fields, and signal acquisition times and their arrangement in time sequence are called the pulse sequence of magnetic resonance imaging. The first pulse sequence and the second pulse sequence can be the same or different. The first pulse sequence and the second pulse sequence are adjacent. The first pulse sequence or the second pulse sequence can be any one of free induction decay sequences, spin echo sequences, inversion recovery sequences, gradient echo sequences, and echo planar imaging sequences. The types of the first pulse sequence and the second pulse sequence are not limited in this embodiment as long as their functions can be realized. Optionally, the parameters of the first pulse sequence and the second pulse sequence have the same settings (center frequency, sequence parameters, coils, etc.), and the first pulse sequence and the second pulse sequence are the same.

[0052] The terminal collects the first magnetic resonance signal and the second magnetic resonance signal. In the magnetic resonance device, the first magnetic resonance signal corresponding to the object to be detected can be obtained through the first pulse sequence, and the second magnetic resonance signal corresponding to the object to be detected can be obtained through the second pulse sequence. The first magnetic resonance signal and the second magnetic resonance signal can be stored in the storage device corresponding to the magnetic resonance device, and the terminal can directly obtain them from the storage device corresponding to the magnetic resonance device when needed. The first magnetic resonance signal and the second magnetic resonance signal can also be directly stored in the memory of the terminal and can be directly obtained from the memory when needed. The specific method for collecting the first magnetic resonance signal and the second magnetic resonance signal is not limited in this embodiment as long as their functions can be realized.

[0053] Step 210: Determine the first spectrum corresponding to the first magnetic resonance signal and the second spectrum corresponding to the second magnetic resonance signal.

[0054] After the terminal acquires the first magnetic resonance signal, it performs a transformation on it to obtain the spectrum corresponding to the first magnetic resonance signal, that is, the first spectrum. The first spectrum refers to the information in the first magnetic resonance signal where the amplitude intensity changes with frequency. Specifically, the terminal can perform a Fourier transform on the first magnetic resonance signal to obtain the first spectrum, or can perform a wavelet transform on the first magnetic resonance signal to obtain the first spectrum. Similarly, after the terminal acquires the second magnetic resonance signal, it performs a transformation on it to obtain the spectrum corresponding to the second magnetic resonance signal, that is, the second spectrum. The second spectrum refers to the information in the second magnetic resonance signal where the amplitude intensity changes with frequency. Specifically, the terminal can perform a Fourier transform on the second magnetic resonance signal to obtain the second spectrum, or can perform a wavelet transform on the second magnetic resonance signal to obtain the second spectrum. This embodiment does not limit the specific method for determining the first spectrum and the second spectrum, as long as its function can be realized.

[0055] Step 220: Determine the relative relaxation spectrum according to the first spectrum and the second spectrum.

[0056] The relaxation process refers to the process from when the atomic nucleus undergoes magnetic resonance to reach a stable high-energy state under the action of a radio frequency pulse until the magnetic moment state before the occurrence of magnetic resonance is restored after the disappearance of the radio frequency pulse.

[0057] During the magnetic resonance scanning process, under the action of the radio frequency pulse corresponding to the first magnetic resonance signal, the second magnetic resonance signal is acquired before the atomic nucleus returns to the magnetic moment state before magnetic resonance. In this way, the obtained magnetic resonance signal will be affected by relaxation (T1 relaxation), and thus the amplitude intensity in the second spectrum will also be affected by relaxation. According to the first spectrum and the second spectrum, the information on how the amplitude intensity in the second spectrum is affected by relaxation can be determined, that is, the relative relaxation spectrum. The relative relaxation spectrum can represent the corresponding relationship between frequency and amplitude intensity under the influence of relaxation. This embodiment does not limit the specific method for determining the relative relaxation spectrum, as long as its function can be realized.

[0058] Step 230: Determine the characteristic frequency of the target imaging nuclide in the target tissue by analyzing the relative relaxation spectrum, and determine the center frequency of the radio frequency system according to the characteristic frequency.

[0059] The target imaging nuclide may include hydrogen atoms 1 H, sodium 23 Na, and phosphorus 31For example, P, etc., the target tissue can include muscle, gray matter of the brain, etc. In this embodiment, the types of target imaging nuclides and the types of target imaging tissues are not limited, and the user can select them according to the actual application scenario. The relative relaxation spectrum includes the frequencies of the target imaging nuclide in different tissues and the amplitude intensities corresponding to the frequencies. After the terminal determines the relative relaxation spectrum, by analyzing the frequencies and amplitude intensities in the relative relaxation spectrum, the characteristic frequency of the target imaging nuclide in the target tissue can be determined. The characteristic frequency refers to the representative frequency of the target imaging nuclide in the target tissue. In this embodiment, the specific method for determining the characteristic frequency of the target imaging nuclide in the target tissue is not limited, as long as its function can be realized.

[0060] After the terminal obtains the characteristic frequency of the target imaging nuclide in the target tissue, it can calibrate the initial center frequency in the RF system according to this characteristic frequency to obtain the final center frequency. In this embodiment, the method for specifically determining the center frequency of the RF system according to the characteristic frequency is not limited, as long as its function can be realized.

[0061] The method for determining the center frequency of the RF system provided by the embodiments of the present application includes collecting a first magnetic resonance signal and a second magnetic resonance signal; determining a first spectrum corresponding to the first magnetic resonance signal and a second spectrum corresponding to the second magnetic resonance signal; determining a relative relaxation spectrum according to the first spectrum and the second spectrum; determining the characteristic frequency of the target imaging nuclide in the target tissue by analyzing the relative relaxation spectrum, and determining the center frequency of the RF system according to the characteristic frequency. The method for determining the center frequency of the RF system provided by the embodiments of the present application takes into account the influence of relaxation on the magnetic resonance signal, that is, the spectrum corresponding to the second magnetic resonance signal will be affected by relaxation. By analyzing the difference between the second spectrum corresponding to the second magnetic resonance signal and the first spectrum corresponding to the first magnetic resonance signal, the frequency of the target imaging nuclide in the target tissue can be found more accurately, thereby improving the accuracy of determining the characteristic frequency of the target imaging nuclide in the target tissue. Furthermore, the characteristic frequency can be used to accurately calibrate the frequency of the RF system in the magnetic resonance device to obtain the center frequency of the RF system. In addition, compared with the traditional technology that uses a single spectral line analysis, the present application determines the characteristic frequency of the target imaging nuclide in the target tissue by analyzing the relative relaxation spectrum, which is applicable to scenarios with different field strengths, where the frequency characteristics of the target imaging nuclide in the target tissue are not obvious, and the reliability requirements for the frequency calibration result are high. That is, the method for determining the center frequency of the RF system provided by the present application has high applicability.

[0062] In one embodiment, an RF pulse is applied between the first pulse sequence and the second pulse sequence; the RF pulse has a preset flip angle.

[0063] After obtaining the first magnetic resonance signal according to the first pulse sequence and before the second pulse sequence appears, a radio frequency pulse with a preset flip angle is applied to the object to be detected. The flip angle can be determined according to factors such as the specific absorption ratio (SAR) of the radio frequency, the acquisition time, the composition of the target tissue, and the field strength. Under the excitation of this radio frequency pulse, the macroscopic magnetization intensity vector will deviate from the direction of the static magnetic field by a preset flip angle. Specifically, the radio frequency pulse can be a square pulse, a sinc waveform pulse, an adiabatic pulse, etc. This embodiment does not limit the specific form of the radio frequency pulse, as long as its function can be realized.

[0064] In this embodiment, by applying a radio frequency pulse with a flip angle between the first pulse sequence and the second pulse sequence, the influence of relaxation on the amplitude intensity of different tissues in the second spectrum can be improved (the amplitude intensity of different tissues in the second spectrum has different degrees of attenuation compared with that of different tissues in the first spectrum). Thus, the accuracy of determining the characteristic frequency of the target imaging nuclide in the target tissue according to the relative relaxation spectrum can be improved, and further the accuracy of determining the center frequency of the radio frequency system can be improved.

[0065] In an alternative embodiment, the radio frequency pulse with a flip angle can be included in the first pulse sequence or the second pulse sequence. That is to say, if the radio frequency pulse is included in the first pulse sequence or the second pulse sequence, and then the radio frequency pulse with a flip angle is applied, the accuracy of determining the center frequency of the radio frequency system can also be improved.

[0066] In one embodiment, a dephasing gradient is applied within a preset time after the radio frequency pulse.

[0067] After a preset time of applying the radio frequency pulse to the object to be detected, a dephasing gradient is applied to the object to be detected. The preset time is between the time of applying the radio frequency pulse and the appearance of the second pulse sequence. By applying the dephasing gradient after the radio frequency pulse, the influence of unexpected magnetic resonance signals can be reduced (for example: the intensity of the free induction decay signal generated by the first pulse sequence can be reduced), the accuracy of the second magnetic resonance signal can be improved, thus the characteristic frequency of the target imaging nuclide in the target tissue can be determined more accurately, and further the accuracy of determining the center frequency of the radio frequency system can be improved. This embodiment does not limit the specific information of the dephasing gradient, as long as its function can be realized.

[0068] In an alternative embodiment, the first pulse sequence includes a square radio frequency pulse and the acquisition of the first magnetic resonance signal, and the second pulse sequence includes a square radio frequency pulse and the acquisition of the second magnetic resonance signal. As Figure 3 shown, the free induction decay signals generated by using the square radio frequency pulse are the first magnetic resonance signal and the second magnetic resonance signal. Figure 3Among them, in the left dashed box on the RF (Radio Frequency, RF) axis, the rectangle represents the square RF pulse in the first pulse sequence, and in the right dashed box, the rectangle represents the square RF pulse in the second pulse sequence. The rectangle in the left dashed box on the ADC axis represents the first magnetic resonance signal acquisition, and the rectangle in the right dashed box represents the second magnetic resonance signal acquisition; the rectangle between the two dashed boxes refers to the RF pulse with a flip angle applied between the first pulse sequence and the second pulse sequence, and the trapezoid between the two dashed boxes refers to the dephasing gradient applied after the RF pulse. The preset time for applying the dephasing gradient after the RF pulse is less than the time t between the equivalent center of the applied RF pulse and the equivalent center of the second pulse sequence. Figure 3 The sequence diagram in can be used for scanning when the signal-to-noise ratio is low.

[0069] In another optional embodiment, the first pulse sequence includes an RF pulse, a gradient, and a first magnetic resonance signal acquisition, and the second pulse sequence includes an RF pulse, a gradient, and a second magnetic resonance signal acquisition. Among them, the gradient includes the gradient G1 on the first direction axis, the gradient G2 on the second direction axis, and the gradient G3 on the third direction axis. As Figure 4 shown. Figure 4 In, the left dashed box is the first pulse sequence, and the right dashed box is the second pulse sequence. The rectangles in the two dashed boxes refer to the RF pulses applied between the first pulse sequence and the second pulse sequence. Figure 4 The sequence diagram in can be used in scenarios with high requirements for imaging effects.

[0070] Please refer to Figure 5 , in one embodiment, it involves a possible implementation method for determining the relative relaxation spectrum according to the first spectrum and the second spectrum. The specific steps include:

[0071] Step 500: Determine the proportional relationship between the first spectrum and the second spectrum.

[0072] The proportional relationship between the first spectrum and the second spectrum can be the first spectrum divided by the second spectrum, or the second spectrum divided by the first spectrum. After the terminal obtains the first spectrum and the second spectrum, it determines the proportional relationship between the first spectrum and the second spectrum. This embodiment does not limit the specific method for determining the proportional relationship between the first spectrum and the second spectrum, as long as its function can be achieved.

[0073] Step 510: Determine the relative relaxation spectrum according to the proportional relationship.

[0074] After obtaining the proportional relationship between the first spectrum and the second spectrum, the terminal can determine the relative relaxation spectrum according to this proportional relationship. Specifically, the ratio between the first spectrum and the second spectrum is the relative relaxation spectrum. That is to say, the proportional relationship between the first spectrum and the second spectrum is used to characterize the information of the amplitude intensity in the second spectrum affected by relaxation.

[0075] In one embodiment, a possible implementation of determining the relative relaxation spectrum according to the first spectrum and the second spectrum is involved. The specific steps include:

[0076] Calculate the difference between the first spectrum and the second spectrum, and determine the relative relaxation spectrum according to the difference.

[0077] After obtaining the first spectrum and the second spectrum, the terminal calculates the difference between the first spectrum and the second spectrum. This difference can be the difference after subtracting the second spectrum from the first spectrum, or the difference after subtracting the first spectrum from the second spectrum. This embodiment does not limit the specific calculation method of the difference, as long as its function can be realized. After obtaining the difference, the terminal uses this difference as the relative relaxation spectrum. That is to say, the difference between the first spectrum and the second spectrum is used to characterize the information of the amplitude intensity in the second spectrum affected by relaxation.

[0078] In this embodiment, two methods for determining the relative relaxation spectrum are provided, and each method is simple and easy to implement. Users can select according to actual needs, making the method for determining the center frequency of the radio frequency system provided in this embodiment highly practical.

[0079] Please refer to Figure 6 , in one embodiment, it is involved in determining the characteristic frequency of the target imaging nuclide in the target tissue by analyzing the relative relaxation spectrum, including:

[0080] Step 600: Determine the correspondence between different tissues and frequencies by analyzing the relative relaxation spectrum.

[0081] The relative relaxation spectrum includes the spectra of the target imaging nuclide in different tissues. By analyzing the relative relaxation spectrum, the terminal can determine the correspondence between different tissues and frequencies in the relative relaxation spectrum. That is to say, by analyzing the relative relaxation spectrum, the terminal can obtain the frequencies corresponding to each tissue.

[0082] Step 610: Determine the frequency of the target imaging nuclide in the target tissue according to the correspondence between different tissues and frequencies.

[0083] Step 620: Determine the characteristic frequency according to the frequency of the target imaging nuclide in the target tissue.

[0084] After the terminal obtains the correspondence between different tissues and frequencies, it searches for the frequency corresponding to the target tissue in the correspondence between different tissues and frequencies. Specifically, the terminal can first find the target tissue among various tissues, and then obtain the frequency of the target tissue according to the correspondence between different tissues and frequencies, that is, the frequency of the target imaging nuclide in the target tissue.

[0085] After the terminal obtains the frequency of the target imaging nuclide in the target tissue, it determines the characteristic frequency of the target imaging nuclide in the target tissue according to this frequency. This embodiment does not limit the method for determining the characteristic frequency, as long as its function can be realized.

[0086] In one embodiment, as Figure 7 shown, it relates to a possible implementation manner of determining the correspondence between different tissues and frequencies by analyzing the relative relaxation spectrum. The steps include:

[0087] Step 700: Obtain the amplitude intensity changes of different frequencies according to the relative relaxation spectrum.

[0088] The relative relaxation spectrum represents the correspondence between frequency and amplitude intensity. The amplitude intensity of different frequencies will change under the influence of relaxation. By analyzing the relative relaxation spectrum, the terminal can obtain the amplitude intensity changes of different frequencies in the relative relaxation spectrum. This embodiment does not limit the specific method for obtaining the amplitude intensity changes of different frequencies, as long as its function can be realized.

[0089] Step 710: Determine the correspondence between different tissues and frequencies according to the amplitude intensity changes of different frequencies and the preset intensity change conditions of different tissues.

[0090] The variations in the amplitude intensity corresponding to the frequencies of different tissues are different, and the preset intensity change conditions for different tissues correspond to different tissues. The terminal determines the frequencies corresponding to the preset tissues by comparing the variations in the amplitude intensity at different frequencies with the preset intensity change conditions for different tissues respectively. The preset tissues are the tissues corresponding to the preset intensity change conditions for different tissues, so as to obtain the correspondence between different tissues and frequencies. The preset intensity change conditions for different tissues may refer to the preset intensity thresholds for different tissues. If the variation in the amplitude intensity is greater than or equal to the preset intensity threshold, it means that the variation in the amplitude intensity meets the preset intensity change conditions. If the variation in the amplitude intensity is less than the preset intensity threshold, it means that the variation in the amplitude intensity does not meet the preset intensity change conditions. Specifically, different tissues include white matter and gray matter in the brain. Assuming that the intensity change condition corresponding to white matter is the first intensity change condition and the intensity change condition corresponding to gray matter is the second intensity change condition, the terminal compares the obtained variation in the amplitude intensity with the first intensity change condition, and determines the frequency corresponding to the variation in the amplitude intensity that meets the first intensity change condition as the frequency corresponding to white matter; the terminal compares the obtained variation in the amplitude intensity with the second intensity change condition, and determines the frequency corresponding to the variation in the amplitude intensity that meets the second intensity change condition as the frequency corresponding to gray matter, so as to obtain the correspondence between white matter and its corresponding frequency, and the correspondence between gray matter and its corresponding frequency.

[0091] The method for determining the frequency of the target imaging radionuclide in the target tissue provided in this embodiment is fast, easy to understand, and easy to implement.

[0092] In a specific embodiment, in the second pulse sequence as Figure 3 shown, that is, when the second pulse sequence only includes one radiofrequency pulse, when the time t between the equivalent center of the applied radiofrequency pulse and the equivalent center of the radiofrequency pulse in the second pulse sequence satisfies that the longitudinal magnetization vector of the target tissue just recovers to zero, that is, the proportion of the magnetic resonance signal of the target tissue in the second frequency spectrum is small. The applied radiofrequency pulse is denoted as the target radiofrequency pulse. According to the formula for the change of signal intensity with time during the inversion recovery process: The time t when the theoretical value of the relative relaxation spectrum of a certain tissue is zero when the flip angle of the target radiofrequency pulse is 180 degrees can be calculated, as well as the theoretical value of the relative relaxation spectrum of another tissue at this time t. Among them, S(t) represents the magnetic resonance signal intensity at time t, S0 represents the magnetic resonance signal intensity that can be obtained only with the second pulse sequence, and T1 represents the T1 relaxation time constant. For example, for head imaging, the T1 relaxation time constant of white matter in the brain is about 510 ms at 1.5T, and the T1 relaxation time constant of gray matter in the brain is about 760 ms. To make the magnetic resonance signal of white matter in the brain account for a relatively small proportion in the second spectrum, substituting the relaxation time constant T1 = 510 ms of white matter into the above formula, it can be calculated that the signal intensity of white matter is 0 when t = 354 ms. Substituting the relaxation time constant T1 = 760 ms of gray matter and t = 354 ms into the above formula, the signal intensity of gray matter is calculated to be 0.26S0. When the parameters of the first pulse sequence and the second pulse sequence are the same, the theoretical values of the relative relaxation spectra of gray matter and white matter calculated by dividing the second spectrum by the first spectrum will be 0 and 0.26 respectively. Determine the preset intensity change conditions corresponding to gray matter according to the theoretical value of the relative relaxation spectrum of gray matter, determine the preset intensity change conditions corresponding to white matter according to the theoretical value of the relative relaxation spectrum of white matter, compare the amplitude intensity changes obtained from the relative relaxation spectrum with the preset intensity change conditions corresponding to gray matter and the preset intensity change conditions corresponding to white matter respectively, determine the frequency corresponding to gray matter as the frequency corresponding to the amplitude intensity change that satisfies the preset intensity change conditions corresponding to gray matter, and determine the frequency corresponding to white matter as the frequency corresponding to the amplitude intensity change that satisfies the preset intensity change conditions corresponding to white matter.

[0093] In an alternative embodiment, a possible implementation manner for determining the characteristic frequency of a target imaging radionuclide in a target tissue by analyzing the relative relaxation spectrum is provided, including:

[0094] The terminal can calculate the theoretical value of the relative relaxation spectrum based on the extended phase graph (EPG) algorithm, using the relaxation time constant of the target tissue, the flip angle of the radiofrequency pulse in the first pulse sequence, the flip angle of the radiofrequency pulse in the second pulse sequence, the flip angle of the radiofrequency pulse applied between the first pulse sequence and the second pulse sequence, and the time t between the equivalent center of this radiofrequency pulse and the equivalent center of the radiofrequency pulse in the second pulse sequence. Determine the characteristic frequency of the target imaging radionuclide in the target tissue according to the difference (weight) between the relative relaxation spectrum and the theoretical value of the relative relaxation spectrum.

[0095] Specifically, assuming that the target tissue is muscle, the calculated theoretical value of the relative relaxation spectrum is 0.26, and the amplitude intensities corresponding to each frequency in the relative relaxation spectrum are 0.1, 0.05, 0.11, 0.19, 0.23, 0.25, 0.27, 0.24, 0.20, 0.14, 0.11. The difference between the relative relaxation spectrum and the theoretical value of the relative relaxation spectrum can be expressed by the ratio between the relative relaxation spectrum and the theoretical value of the relative relaxation spectrum, that is, the ratio obtained by dividing the relative relaxation spectrum by the theoretical value of the relative relaxation spectrum. When the ratio is greater than 1 or less than 2, the difference between 2 and the ratio is taken; when the ratio is greater than 2, 0 is taken. According to the relative relaxation spectrum and the theoretical value of the relative relaxation spectrum, the weights corresponding to the amplitude intensities in the relative relaxation spectrum can be obtained as 0.38, 0.19, 0.42, 0.73, 0.88, 0.96, 0.96, 0.92, 0.77, 0.54, 0.42. Applying the weights and the spectral analysis method can obtain the characteristic frequency of the target imaging radionuclide in the target tissue. Specifically, the frequencies corresponding to the amplitude intensities within a preset range can be weighted and determined as the frequencies of the target imaging radionuclide in the target tissue, and then the characteristic frequency can be determined according to the frequencies of the target imaging radionuclide in the target tissue.

[0096] In another embodiment, the calculation method for the difference (weight) between the relative relaxation spectrum and the theoretical value of the relative relaxation spectrum further includes: taking the 1-norm of the difference, that is, 1 - |the amplitude intensity of the relative relaxation spectrum - the theoretical value of the relative relaxation spectrum|, and taking the value less than 1 as zero; taking the 2-norm of the difference, that is, 1 - (the amplitude intensity of the relative relaxation spectrum - the theoretical value of the relative relaxation spectrum) 2 , and taking the value less than 1 as zero.

[0097] In one embodiment, a possible implementation manner for determining the characteristic frequency according to the frequency of the target imaging radionuclide in the target tissue is involved, and the steps include:

[0098] Obtain the spectrum of the target imaging radionuclide in the target tissue; calculate the maximum value of the amplitude intensity in the spectrum, and take the frequency corresponding to the maximum value of the amplitude intensity as the central frequency.

[0099] After the terminal determines the frequency of the target imaging radionuclide in the target tissue from the relative relaxation spectrum, it obtains the amplitude intensity corresponding to this frequency; according to this frequency and the amplitude intensity corresponding to this frequency, it obtains the spectrum of the target imaging radionuclide in the target tissue. After the terminal obtains the spectrum of the target imaging radionuclide in the target tissue, it compares the amplitude intensities in this spectrum, finds the maximum value of the amplitude intensities, and takes the frequency corresponding to the maximum value of the amplitude intensity as the characteristic frequency of the target imaging radionuclide in the target tissue.

[0100] In one embodiment, a possible implementation method for determining the characteristic frequency according to the frequency of the target imaging radionuclide in the target tissue is involved, and the steps include:

[0101] Perform fitting processing on the frequency of the target imaging radionuclide in the target tissue to obtain the characteristic frequency.

[0102] After the terminal obtains the frequency of the target imaging radionuclide in the target tissue, all the frequencies are subjected to fitting processing according to the fitting algorithm, and the characteristic frequency of the target imaging radionuclide in the target tissue can be obtained. Specifically, the fitting algorithms include the least squares method and algorithms such as finding the pseudoinverse of the matrix. In this embodiment, the specific process of performing fitting processing on the frequency of the target imaging radionuclide in the target tissue is not limited as long as its function can be realized.

[0103] It should be understood that although the steps in the flowchart in the figure are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless there is a clear description in this article, the execution of these steps has no strict order limit, and these steps can be executed in other orders. Moreover, at least a part of the steps in the figure may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed alternately or alternately with at least a part of other steps or sub-steps or stages of other steps.

[0104] Based on the same inventive concept, an embodiment of the present application also provides a device for determining the center frequency of a radio frequency system for implementing the method for determining the center frequency of a radio frequency system involved above. The solution provided by this device to solve the problem is similar to the solution described in the above method. Therefore, the specific limitations in one or more embodiments of the device for determining the center frequency of a radio frequency system provided below can refer to the limitations on the method for determining the center frequency of a radio frequency system in the above text, and will not be repeated here.

[0105] Please refer to Figure 8 , an embodiment of the present application provides a device 10 for determining the center frequency of a radio frequency system. The device includes an acquisition module 11, a first determination module 12, a second determination module 13, and a third determination module 14. Among them,

[0106] The acquisition module 11 is used to acquire a first magnetic resonance signal and a second magnetic resonance signal. The first magnetic resonance signal is obtained by a first pulse sequence, and the second magnetic resonance signal is obtained by a second pulse sequence. The first pulse sequence and the second pulse sequence are arranged adjacent to each other;

[0107] The first determination module 12 is used to determine a first frequency spectrum corresponding to the first magnetic resonance signal and a second frequency spectrum corresponding to the second magnetic resonance signal;

[0108] The second determination module 13 is used to determine the relative relaxation frequency spectrum according to the first frequency spectrum and the second frequency spectrum;

[0109] The third determination module 14 is configured to determine the characteristic frequency of the target imaging nuclide in the target tissue by analyzing the relative relaxation spectrum, and determine the center frequency of the radio frequency system according to the characteristic frequency.

[0110] In one embodiment, a radio frequency pulse is applied between the first pulse sequence and the second pulse sequence; the radio frequency pulse has a preset flip angle.

[0111] In one embodiment, a dephasing gradient is applied within a preset time after the radio frequency pulse.

[0112] In one embodiment, the second determination module 13 is specifically configured to determine the proportional relationship between the first spectrum and the second spectrum; determine the relative relaxation spectrum according to the proportional relationship.

[0113] In one embodiment, the second determination module 13 is further specifically configured to calculate the difference between the first spectrum and the second spectrum, and determine the relative relaxation spectrum according to the difference.

[0114] In one embodiment, the third determination module 14 includes a first determination unit, a second determination unit, and a third determination unit. The first determination unit is configured to determine the correspondence between different tissues and frequencies by analyzing the relative relaxation spectrum; the second determination unit is configured to determine the frequency of the target imaging nuclide in the target tissue according to the correspondence between different tissues and frequencies; the third determination unit is configured to determine the characteristic frequency according to the frequency of the target imaging nuclide in the target tissue.

[0115] In one embodiment, the second determination unit is specifically configured to obtain the amplitude intensity change at different frequencies according to the relative relaxation spectrum; determine the correspondence between different tissues and frequencies according to the amplitude intensity change at different frequencies and the preset intensity change conditions of different tissues.

[0116] In one embodiment, the third determination unit is configured to obtain the spectrum of the target imaging nuclide in the target tissue; calculate the maximum value of the amplitude intensity in the spectrum, and use the frequency corresponding to the maximum value of the amplitude intensity as the characteristic frequency.

[0117] In one embodiment, the third determination unit is further configured to perform a fitting process on the frequency of the target imaging nuclide in the target tissue to obtain the characteristic frequency.

[0118] Each module in the above radio frequency system center frequency determination device can be implemented in whole or in part by software, hardware, and their combination. The above modules can be embedded in or independent of the processor in the computer device in the form of hardware, or stored in the memory of the computer device in the form of software, so that the processor can call and execute the operations corresponding to the above modules.

[0119] In one embodiment, a computer device is provided. The computer device may be a terminal, and its internal structure diagram may be as shown in Figure 9 . The computer device includes a processor, a memory, a communication interface, a display screen, and an input device connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner. The wireless manner can be implemented through WIFI, a mobile cellular network, NFC (Near Field Communication), or other technologies. When the computer program is executed by the processor, it implements a method for determining the center frequency of a radio frequency system. The display screen of the computer device may be a liquid crystal display screen or an electronic ink display screen. The input device of the computer device may be a touch layer covering the display screen, or a button, a trackball, or a touchpad provided on the housing of the computer device, or an external keyboard, touchpad, or mouse, etc.

[0120] Those skilled in the art can understand that Figure 9 the structure shown in is only a block diagram of some structures related to the solution of this application, and does not constitute a limitation on the computer device to which the solution of this application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine some components, or have different component arrangements.

[0121] In one embodiment, a computer device is provided, including a memory and a processor. A computer program is stored in the memory. When the processor executes the computer program, the following steps are implemented:

[0122] Collect a first magnetic resonance signal and a second magnetic resonance signal. The first magnetic resonance signal is obtained by a first pulse sequence, and the second magnetic resonance signal is obtained by a second pulse sequence. The first pulse sequence and the second pulse sequence are arranged adjacent to each other;

[0123] Determine a first frequency spectrum corresponding to the first magnetic resonance signal and a second frequency spectrum corresponding to the second magnetic resonance signal;

[0124] Determine a relative relaxation frequency spectrum according to the first frequency spectrum and the second frequency spectrum;

[0125] Determine the characteristic frequency of the target imaging nuclide in the target tissue by analyzing the relative relaxation frequency spectrum, and determine the center frequency of the radio frequency system according to the characteristic frequency.

[0126] In one embodiment, a radio frequency pulse is applied between the first pulse sequence and the second pulse sequence; the radio frequency pulse has a preset flip angle.

[0127] In one embodiment, a dephasing gradient is applied within a preset time after the radio frequency pulse.

[0128] In one embodiment, when the processor executes the computer program, the following steps are further implemented: determining the proportional relationship between the first spectrum and the second spectrum; determining the relative relaxation spectrum according to the proportional relationship.

[0129] In one embodiment, when the processor executes the computer program, the following steps are further implemented: calculating the difference between the first spectrum and the second spectrum, and determining the relative relaxation spectrum according to the difference.

[0130] In one embodiment, when the processor executes the computer program, the following steps are further implemented: determining the correspondence between different tissues and frequencies by analyzing the relative relaxation spectrum; determining the frequency of the target imaging nuclide in the target tissue according to the correspondence between different tissues and frequencies; determining the characteristic frequency according to the frequency of the target imaging nuclide in the target tissue.

[0131] In one embodiment, when the processor executes the computer program, the following steps are further implemented: obtaining the amplitude intensity changes at different frequencies according to the relative relaxation spectrum; determining the correspondence between different tissues and frequencies according to the amplitude intensity changes at different frequencies and the preset intensity change conditions of different tissues.

[0132] In one embodiment, when the processor executes the computer program, the following steps are further implemented: obtaining the spectrum of the target imaging nuclide in the target tissue; calculating the maximum value of the amplitude intensity in the spectrum, and taking the frequency corresponding to the maximum value of the amplitude intensity as the characteristic frequency.

[0133] In one embodiment, when the processor executes the computer program, the following steps are further implemented: performing fitting processing on the frequency of the target imaging nuclide in the target tissue to obtain the characteristic frequency.

[0134] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the following steps are implemented:

[0135] Collecting a first magnetic resonance signal and a second magnetic resonance signal, where the first magnetic resonance signal is obtained by a first pulse sequence, the second magnetic resonance signal is obtained by a second pulse sequence, and the first pulse sequence and the second pulse sequence are arranged adjacent to each other;

[0136] Determining a first spectrum corresponding to the first magnetic resonance signal and a second spectrum corresponding to the second magnetic resonance signal;

[0137] Determining a relative relaxation spectrum according to the first spectrum and the second spectrum;

[0138] Determine the characteristic frequency of the target imaging radionuclide in the target tissue by analyzing the relative relaxation spectrum, and determine the center frequency of the radio frequency system according to the characteristic frequency.

[0139] In one embodiment, a radio frequency pulse is applied between the first pulse sequence and the second pulse sequence; the radio frequency pulse has a preset flip angle.

[0140] In one embodiment, a dephasing gradient is applied within a preset time after the radio frequency pulse.

[0141] In one embodiment, when the computer program is executed by a processor, the following steps are further implemented: determine the proportional relationship between the first spectrum and the second spectrum; determine the relative relaxation spectrum according to the proportional relationship.

[0142] In one embodiment, when the computer program is executed by a processor, the following steps are further implemented: calculate the difference between the first spectrum and the second spectrum, and determine the relative relaxation spectrum according to the difference.

[0143] In one embodiment, when the computer program is executed by a processor, the following steps are further implemented: determine the correspondence between different tissues and frequencies by analyzing the relative relaxation spectrum; determine the frequency of the target imaging radionuclide in the target tissue according to the correspondence between different tissues and frequencies; determine the characteristic frequency according to the frequency of the target imaging radionuclide in the target tissue.

[0144] In one embodiment, when the computer program is executed by a processor, the following steps are further implemented: obtain the amplitude intensity changes at different frequencies according to the relative relaxation spectrum; determine the correspondence between different tissues and frequencies according to the amplitude intensity changes at different frequencies and the preset intensity change conditions of different tissues.

[0145] In one embodiment, when the computer program is executed by a processor, the following steps are further implemented: obtain the spectrum of the target imaging radionuclide in the target tissue; calculate the maximum value of the amplitude intensity in the spectrum, and use the frequency corresponding to the maximum value of the amplitude intensity as the characteristic frequency.

[0146] In one embodiment, when the computer program is executed by a processor, the following steps are further implemented: perform fitting processing on the frequency of the target imaging radionuclide in the target tissue to obtain the characteristic frequency.

[0147] In one embodiment, a computer program product is provided, including a computer program, and when the computer program is executed by a processor, the following steps are implemented:

[0148] Collect a first magnetic resonance signal and a second magnetic resonance signal. The first magnetic resonance signal is obtained by a first pulse sequence, and the second magnetic resonance signal is obtained by a second pulse sequence. The first pulse sequence and the second pulse sequence are arranged adjacent to each other;

[0149] Determine the first spectrum corresponding to the first magnetic resonance signal and the second spectrum corresponding to the second magnetic resonance signal;

[0150] Determine the relative relaxation spectrum according to the first spectrum and the second spectrum;

[0151] Determine the characteristic frequency of the target imaging nuclide in the target tissue by analyzing the relative relaxation spectrum, and determine the center frequency of the radio frequency system according to the characteristic frequency.

[0152] In one embodiment, a radio frequency pulse is applied between the first pulse sequence and the second pulse sequence; the radio frequency pulse has a preset flip angle.

[0153] In one embodiment, a dephasing gradient is applied within a preset time after the radio frequency pulse.

[0154] In one embodiment, when the computer program is executed by a processor, the following steps are further implemented: determine the proportional relationship between the first spectrum and the second spectrum; determine the relative relaxation spectrum according to the proportional relationship.

[0155] In one embodiment, when the computer program is executed by a processor, the following steps are further implemented: calculate the difference between the first spectrum and the second spectrum, and determine the relative relaxation spectrum according to the difference.

[0156] In one embodiment, when the computer program is executed by a processor, the following steps are further implemented: determine the correspondence between different tissues and frequencies by analyzing the relative relaxation spectrum; determine the frequency of the target imaging nuclide in the target tissue according to the correspondence between different tissues and frequencies; determine the characteristic frequency according to the frequency of the target imaging nuclide in the target tissue.

[0157] In one embodiment, when the computer program is executed by a processor, the following steps are further implemented: obtain the amplitude intensity change of different frequencies according to the relative relaxation spectrum; determine the correspondence between different tissues and frequencies according to the amplitude intensity change of different frequencies and the preset intensity change conditions of different tissues.

[0158] In one embodiment, when the computer program is executed by a processor, the following steps are further implemented: obtain the spectrum of the target imaging nuclide in the target tissue; calculate the maximum value of the amplitude intensity in the spectrum, and use the frequency corresponding to the maximum value of the amplitude intensity as the center frequency.

[0159] In one embodiment, when the computer program is executed by a processor, the following steps are further implemented: perform fitting processing on the frequency of the target imaging nuclide in the target tissue to obtain the characteristic frequency.

[0160] Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above various methods. Among them, any reference to a memory, storage, database, or other medium used in the various embodiments provided in the present application can include non-volatile and / or volatile memories. Non-volatile memories can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memories can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and Rambus dynamic RAM (RDRAM), etc.

[0161] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, 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, it should be considered as the scope described in this specification.

[0162] The above-described embodiments merely represent several implementation manners of the present application. Their descriptions are relatively specific and detailed, but they should not be construed as limiting the patent scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the appended claims.

Claims

1. A method for determining the center frequency of a radio frequency system, characterized in that, Comprising: Collecting a first magnetic resonance signal and a second magnetic resonance signal, where the first magnetic resonance signal is obtained by a first pulse sequence, the second magnetic resonance signal is obtained by a second pulse sequence, and the first pulse sequence and the second pulse sequence are arranged adjacent to each other; Determining a first frequency spectrum corresponding to the first magnetic resonance signal and a second frequency spectrum corresponding to the second magnetic resonance signal; Determining a relative relaxation frequency spectrum according to the first frequency spectrum and the second frequency spectrum; the relative relaxation frequency spectrum includes the frequencies of the target imaging nuclide in different tissues and the amplitude intensities corresponding to the frequencies; Determining the characteristic frequency of the target imaging nuclide in the target tissue by analyzing the relative relaxation frequency spectrum, and determining the center frequency of the radio frequency system according to the characteristic frequency; Wherein, determining the center frequency of the radio frequency system according to the characteristic frequency includes: calibrating the initial center frequency of the radio frequency system according to the characteristic frequency to obtain the center frequency of the radio frequency system.

2. The method for determining the center frequency of the radio frequency system according to claim 1, wherein A radio frequency pulse is applied between the first pulse sequence and the second pulse sequence; the radio frequency pulse has a preset flip angle.

3. The method for determining the center frequency of the radio frequency system according to claim 2, characterized in that A dephasing gradient is applied within a preset time after the radio frequency pulse.

4. The method for determining the center frequency of the radio frequency system according to any one of claims 1-3, characterized in that, The determining the relative relaxation frequency spectrum according to the first frequency spectrum and the second frequency spectrum includes: Determining the proportional relationship between the first frequency spectrum and the second frequency spectrum, and determining the relative relaxation frequency spectrum according to the proportional relationship; Or, calculating the difference between the first frequency spectrum and the second frequency spectrum, and determining the relative relaxation frequency spectrum according to the difference.

5. The method for determining the center frequency of the radio frequency system according to claim 1, wherein The determining the characteristic frequency of the target imaging nuclide in the target tissue by analyzing the relative relaxation frequency spectrum includes: Determining the corresponding relationship between the different tissues and the frequencies by analyzing the relative relaxation frequency spectrum; Determining the frequency of the target imaging nuclide in the target tissue according to the corresponding relationship between the different tissues and the frequencies; Determining the characteristic frequency according to the frequency of the target imaging nuclide in the target tissue.

6. The method for determining the center frequency of the radio frequency system according to claim 5, wherein The determining the corresponding relationship between the different tissues and the frequencies by analyzing the relative relaxation frequency spectrum includes: Obtaining the change in amplitude intensity at different frequencies according to the relative relaxation frequency spectrum; Determining the corresponding relationship between the different tissues and the frequencies according to the change in amplitude intensity at different frequencies and the preset intensity change conditions of the different tissues.

7. The method for determining the center frequency of the radio frequency system according to claim 5, wherein The determining the characteristic frequency according to the frequency of the target imaging nuclide in the target tissue includes: Obtaining the frequency spectrum of the target imaging nuclide in the target tissue; Calculating the maximum value of the amplitude intensity in the frequency spectrum, and taking the frequency corresponding to the maximum value of the amplitude intensity as the characteristic frequency.

8. The method for determining the center frequency of the radio frequency system according to claim 5, wherein The determining the characteristic frequency according to the frequency of the target imaging nuclide in the target tissue includes: Performing a fitting process on the frequency of the target imaging nuclide in the target tissue to obtain the characteristic frequency.

9. A central frequency determination device for a radio frequency system, characterized in that, Comprising: An acquisition module for acquiring a first magnetic resonance signal and a second magnetic resonance signal, where the first magnetic resonance signal is obtained by a first pulse sequence, the second magnetic resonance signal is obtained by a second pulse sequence, and the first pulse sequence and the second pulse sequence are arranged adjacent to each other; A first determination module, configured to determine a first frequency spectrum corresponding to the first magnetic resonance signal and a second frequency spectrum corresponding to the second magnetic resonance signal; A second determination module, configured to determine a relative relaxation frequency spectrum according to the first frequency spectrum and the second frequency spectrum; the relative relaxation frequency spectrum includes the frequencies of the target imaging nuclide in different tissues and the amplitude intensities corresponding to the frequencies; A third determination module, configured to determine the characteristic frequency of the target imaging nuclide in the target tissue by analyzing the frequencies of different tissues in the relative relaxation frequency spectrum, and determine the center frequency of the radio frequency system according to the characteristic frequency; Specifically, the third determination module is configured to calibrate the initial center frequency of the radio frequency system according to the characteristic frequency to obtain the center frequency of the radio frequency system.

10. A computer device, comprising a memory and a processor, the memory storing a computer program, characterized in that, When the processor executes the computer program, the steps of the method according to any one of claims 1 to 8 are implemented.

11. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, the steps of the method according to any one of claims 1 to 8 are implemented.

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