Method, apparatus, computer device, and storage medium for determining echo interval

Abstract

The present application relates to a method, apparatus, computer device, storage medium, and computer program product for determining an echo interval. The method includes extracting characteristic frequencies of respective characteristic tissues from a frequency spectrum line of an echo signal of a sample to be examined, and determining a target echo time interval between two adjacent echo signals to be set based on the extracted characteristic frequencies and a preset echo time interval. It is possible to determine an accurate target echo time interval, and the target echo time interval is more in line with the actual imaging situation, largely eliminating the influence of chemical shift, improving the active shimming effect, and enhancing the quality of magnetic resonance imaging.

Description

Technical Field

[0001] This application relates to the field of magnetic resonance imaging technology, and in particular, to a method, device, computer device, storage medium, and computer program product for determining an echo spacing. Background Art

[0002] Some magnetic resonance sequences are sensitive to the intensity uniformity of the main magnetic field (B0 field). Usually, active shimming is performed before these sequences to improve the B0 field uniformity. Before performing active shimming, it is necessary to collect the B0 field intensity distribution information of the space through a magnetic resonance sequence. These sequences are usually called B0 field map sequences. Currently, the B0 field intensity distribution information is obtained from the phase difference between two echo signals collected by the B0 field map sequence, and then a B0 field map is obtained based on the B0 field intensity distribution information. Among them, the echo signal is the signal emitted by the excited atomic nuclei of the object to be scanned after being excited by a radio frequency pulse and after the radio frequency pulse stops. However, the phase difference between two echo signals is affected not only by the B0 field uniformity but also by chemical shift, resulting in structural image information caused by chemical shift in the phase difference image and also in the B0 field map. The active shimming analysis based on the B0 field map containing structural image information is not accurate enough. Therefore, it is necessary to eliminate the influence of chemical shift on the B0 field map.

[0003] Currently, the method for eliminating the influence of chemical shift on the B0 field map is to use a preset echo spacing obtained based on theoretical chemical shift to reduce the adverse influence of chemical shift on the B0 field map. However, the preset echo spacing does not always reflect the actual imaging situation. For example, for a subject with a silicone implant prosthesis, the preset echo spacing applicable to the water-fat chemical shift is not appropriate. Therefore, using the preset echo spacing obtained from theoretical chemical shift cannot completely eliminate the influence of chemical shift.

[0004] Therefore, how to accurately determine the echo spacing that needs to be set in the actual imaging situation to eliminate the influence of chemical shift, thereby improving the active shimming effect and the magnetic resonance imaging quality has become an urgent problem to be solved currently. Summary of the Invention

[0005] Based on this, in view of the above technical problems, it is necessary to provide a method, device, computer device, computer-readable storage medium, and computer program product for determining an echo spacing that can accurately determine the echo spacing that needs to be set in the actual imaging situation.

[0006] In a first aspect, this application provides a method for determining an echo spacing. The method includes:

[0007] Extract the characteristic frequencies of each characteristic tissue from the frequency spectrum line of the echo signal of the sample to be examined; wherein, the frequency spectrum line includes the characteristic frequencies of at least one characteristic tissue of the sample to be examined;

[0008] Based on the extracted characteristic frequencies and the preset echo time interval, determine the target echo time interval between two adjacent echo signals to be set.

[0009] In a second aspect, the present application further provides a device for determining an echo interval. The device includes:

[0010] An extraction module, configured to extract the characteristic frequencies of each characteristic tissue from the frequency spectrum line of the echo signal of the sample to be examined; wherein, the frequency spectrum line includes the characteristic frequencies of at least one characteristic tissue of the sample to be examined;

[0011] A determination module, configured to determine the target echo time interval between two adjacent echo signals to be set based on the extracted characteristic frequencies and the preset echo time interval.

[0012] In a third aspect, the present application further provides a computer device. The computer device includes a memory and a processor, the memory stores a computer program, and when the processor executes the computer program, the following steps are implemented:

[0013] Extract the characteristic frequencies of each characteristic tissue from the frequency spectrum line of the echo signal of the sample to be examined; wherein, the frequency spectrum line includes the characteristic frequencies of at least one characteristic tissue of the sample to be examined;

[0014] Based on the extracted characteristic frequencies and the preset echo time interval, determine the target echo time interval between two adjacent echo signals to be set.

[0015] In a fourth aspect, the present application further provides a computer-readable storage medium. The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the following steps are implemented:

[0016] Extract the characteristic frequencies of each characteristic tissue from the frequency spectrum line of the echo signal of the sample to be examined; wherein, the frequency spectrum line includes the characteristic frequencies of at least one characteristic tissue of the sample to be examined;

[0017] Based on the extracted characteristic frequencies and the preset echo time interval, determine the target echo time interval between two adjacent echo signals to be set.

[0018] In a fifth aspect, the present application further provides a computer program product. The computer program product includes a computer program, and when the computer program is executed by a processor, the following steps are implemented:

[0019] Extract the characteristic frequencies of each characteristic tissue from the frequency spectrum line of the echo signal of the sample to be examined; wherein, the frequency spectrum line includes the characteristic frequencies of at least one characteristic tissue of the sample to be examined;

[0020] Based on the extracted characteristic frequencies and the preset echo time interval, determine the target echo time interval between two adjacent echo signals that need to be set.

[0021] The above method, device, computer device, storage medium, and computer program product for determining the echo interval extract the characteristic frequencies of each characteristic tissue from the frequency spectrum line of the echo signal of the sample to be examined, and based on the extracted characteristic frequencies and the preset echo time interval, determine the target echo time interval between two adjacent echo signals that need to be set. Since the target echo time interval is determined based on the characteristic frequencies of each characteristic tissue extracted from the frequency spectrum line of the echo signal of the sample to be examined, the frequency spectrum line can reflect the characteristic frequencies of the characteristic tissues of the sample to be examined during actual imaging, and the characteristic frequencies can reflect the chemical shift between the characteristic tissues during actual imaging. Therefore, an accurate target echo time interval can be determined based on the chemical shift between the characteristic tissues during actual imaging, so that the determined target echo time interval is more in line with the actual imaging situation, largely eliminating the influence of chemical shift, improving the active shimming effect, and improving the quality of magnetic resonance imaging. Description of the Drawings

[0022] Figure 1 is a schematic flowchart of a method for determining an echo interval provided by an embodiment of the present application;

[0023] Figure 2 is a schematic flowchart of a method for determining a target echo time interval provided by an embodiment of the present application;

[0024] Figure 3 is a schematic flowchart of a method for determining a minimum in-phase time interval provided by an embodiment of the present application;

[0025] Figure 4 is a schematic flowchart of a method for determining a frequency difference provided by an embodiment of the present application;

[0026] Figure 5 is one of the schematic diagrams of the frequency spectrum line provided by an embodiment of the present application;

[0027] Figure 6 is another schematic diagram of the frequency spectrum line provided by an embodiment of the present application;

[0028] Figure 7 is a schematic flowchart of another method for determining a target echo time interval provided by an embodiment of the present application;

[0029] Figure 8It is a schematic flowchart of yet another method for determining the target echo time interval provided by an embodiment of the present application;

[0030] Figure 9 It is a schematic flowchart of still another method for determining the target echo time interval provided by an embodiment of the present application;

[0031] Figure 10 It is a schematic flowchart of a method for determining the frequency difference provided by an embodiment of the present application;

[0032] Figure 11 It is a schematic diagram of a method for implementing the B0 field map provided by an embodiment of the present application;

[0033] Figure 12 It is a schematic structural diagram of a device for determining the echo interval provided by an embodiment of the present application;

[0034] Figure 13 It is an internal structural diagram of a computer device in one embodiment. Detailed implementation manners

[0035] In order to make the objectives, technical solutions and advantages of the present application clearer and more understandable, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0036] Refer to Figure 1 , Figure 1 It is a schematic flowchart of a method for determining the echo interval provided by an embodiment of the present application. This method can be applied to a computer device, and the method includes the following steps:

[0037] S101. Extract the characteristic frequencies of each characteristic tissue from the frequency spectrum line of the echo signal of the sample to be examined.

[0038] Among them, the frequency spectrum line includes the characteristic frequencies of at least one characteristic tissue of the sample to be examined.

[0039] In this embodiment, the sample to be examined can be a human tissue or section, an animal tissue or section, etc. Characteristic tissues include, for example, adipose tissue, muscle tissue, bone tissue, etc. The characteristic frequency refers to the frequency of the echo signal emitted by the excited atomic nucleus after the atomic nucleus in the characteristic tissue is excited by a radio frequency pulse. It should be noted that some characteristic tissues, such as fat, have multiple characteristic frequencies, while some other characteristic tissues have only one characteristic frequency.

[0040] S102. Determine the target echo time interval between two adjacent echo signals that need to be set based on the extracted characteristic frequencies and a preset echo time interval.

[0041] Among them, the preset echo time interval can be set to a value greater than or equal to the shortest echo interval allowed by the magnetic resonance system. The shortest echo time interval can be determined by the shortest echo time interval allowed by the radio frequency system in the magnetic resonance system, the shortest echo time interval allowed by the gradient system, and the shortest echo time interval allowed by other hardware.

[0042] The target echo time interval in the prior art is calculated by the following method based on theoretical chemical shift:

[0043] At a magnetic field strength of 3T, the frequency difference Δf between two tissues is Δf = δγB0 = 3.4 ppm * 42.576 MHz / T * 3T = 434.3 Hz. Then, Δt = 1 / 434.3 Hz = 2.30 ms. Therefore, the minimum in-phase time interval between the two tissues is equal to an integer multiple of 2.3. Thus, the preset target echo time interval at a magnetic field strength of 3T is equal to an integer multiple of 2.30 ms. Among them, δ represents the theoretical chemical shift, and γ represents the gyromagnetic ratio. Since the determination of the target echo time interval in the prior art is calculated based on the theoretical chemical shift, the theoretical chemical shift δ does not always reflect the actual imaging situation. For example, for a subject with a silicone implant prosthesis, the preset echo interval applicable to the water-fat chemical shift is not appropriate. Therefore, using the preset echo interval obtained from the theoretical chemical shift cannot eliminate the influence of chemical shift.

[0044] However, for the method for determining the echo interval provided in this embodiment, by extracting the characteristic frequencies of each characteristic tissue from the frequency spectrum of the echo signal of the sample to be examined, and based on the extracted characteristic frequencies and the preset echo time interval, the target echo time interval between two adjacent echo signals to be set is determined. Since the target echo time interval is determined based on the characteristic frequencies of each characteristic tissue extracted from the frequency spectrum of the echo signal of the sample to be examined, the frequency spectrum can reflect the characteristic frequencies of the characteristic tissues of the sample to be examined during actual imaging, and the characteristic frequencies can reflect the chemical shift between the characteristic tissues during actual imaging. Therefore, an accurate target echo time interval can be determined based on the chemical shift between the characteristic tissues during actual imaging, so that the determined target echo time interval is more in line with the actual imaging situation, largely eliminating the influence of chemical shift, improving the active shimming effect, and improving the magnetic resonance imaging quality.

[0045] Optionally, the above S102, determining the target echo time interval between two adjacent echo signals to be set based on the extracted characteristic frequencies and the preset echo time interval, can be implemented in the following manner:

[0046] If the total number of the extracted characteristic frequencies is one, the preset echo time interval is used as the target echo time interval.

[0047] In this embodiment, if the total number of extracted characteristic frequencies is one, the preset echo time interval is used as the target echo time interval. When the total number of extracted characteristic frequencies is one, it means that there is no chemical shift, so the preset echo time interval is used as the target echo time interval. Since the signal-to-noise ratio is improved in this case, the active shimming effect is improved, and the magnetic resonance imaging quality is enhanced.

[0048] Referring to Figure 2 , Figure 2 FIG. is a schematic flowchart of a method for determining a target echo time interval provided by an embodiment of the present application. This embodiment relates to an optional implementation manner of how to determine the target echo time interval between two adjacent echo signals that need to be set based on the extracted characteristic frequencies and the preset echo time interval. On the basis of the above embodiment, S102 can include the following steps:

[0049] S201. If the total number of extracted characteristic frequencies is multiple, based on the multiple characteristic frequencies, determine the minimum in-phase time interval between the echo signal corresponding to the secondary characteristic frequency and the echo signal corresponding to the center frequency among the multiple characteristic frequencies.

[0050] For example, if the total number of extracted characteristic frequencies is 2, one of the characteristic frequencies is the center frequency and the other is the secondary characteristic frequency, then determine the minimum in-phase time interval between the echo signal corresponding to the secondary characteristic frequency and the echo signal corresponding to the center frequency.

[0051] For another example, if the total number of extracted characteristic frequencies is 4, there are 3 secondary characteristic frequencies and 1 center frequency among the 4 characteristic frequencies, and the minimum in-phase time interval between the echo signals corresponding to the 3 secondary characteristic frequencies and the echo signal corresponding to the center frequency can be determined.

[0052] It should be noted that frequency calibration is performed before active shimming analysis. By analyzing the spectrum, one of the characteristic frequencies is set as the center frequency. When there are N characteristic frequencies, one of the N characteristic frequencies is always set as the center frequency during frequency calibration, where N is an integer greater than or equal to 1. Among them, when N equals 1, the one characteristic frequency is directly set as the center frequency, that is, in this case, it is considered that there is no difference between this characteristic frequency and the center frequency, and thus there is no chemical shift.

[0053] S202. Based on the preset echo time interval and the minimum in-phase time interval, determine the target echo time interval.

[0054] Among them, based on the preset echo time interval and the minimum in-phase time interval, the target echo time interval can be determined in the following manner:

[0055] If the minimum in-phase time interval is greater than or equal to the preset echo time interval, then use this minimum in-phase time interval as the target echo time interval;

[0056] If the minimum in-phase time interval is less than the preset echo time interval, then determine the minimum integer multiple of the minimum in-phase time interval as the target echo time interval; where the minimum integer multiple of the minimum in-phase time interval is greater than the preset echo time interval. For example, if the minimum in-phase time interval is equal to 2 ms and the preset echo time interval is equal to 2.5 ms, then use 2×2 ms = 4 ms as the target echo time interval.

[0057] In this embodiment, when the total number of extracted characteristic frequencies is multiple, based on the multiple characteristic frequencies, determine the minimum in-phase time interval between the echo signal corresponding to the secondary characteristic frequency and the echo signal corresponding to the central frequency among the multiple characteristic frequencies, and based on the preset echo time interval and the minimum in-phase time interval, determine the target echo time interval. Since the minimum in-phase time interval is determined based on the multiple extracted characteristic frequencies, that is, the determination of the minimum in-phase time interval takes into account the chemical shift between the characteristic frequencies during actual imaging. Then, based on the preset echo time interval and the minimum in-phase time interval, determine an accurate target echo time interval. The determined target echo time interval is more in line with the actual imaging situation, largely eliminating the influence of chemical shift, improving the active shimming effect, and enhancing the quality of magnetic resonance imaging.

[0058] Refer to Figure 3 , Figure 3 is a schematic flowchart of a method for determining the minimum in-phase time interval provided by an embodiment of the present application. This embodiment relates to an optional implementation manner of how to determine the minimum in-phase time interval between the echo signal corresponding to the secondary characteristic frequency and the echo signal corresponding to the central frequency among the multiple characteristic frequencies based on the multiple characteristic frequencies. On the basis of the above embodiment, the above S201 may include the following steps:

[0059] S301. Determine the frequency difference between the central frequency and the secondary characteristic frequency.

[0060] For example, if there are two secondary characteristic frequencies, namely secondary characteristic frequency 1 and secondary characteristic frequency 2, among the multiple characteristic frequencies, then the frequency difference 1 and the frequency difference 2 can be determined. The frequency difference 1 is equal to the frequency difference between the central frequency and the secondary characteristic frequency 1, and the frequency difference 2 is equal to the frequency difference between the central frequency and the secondary characteristic frequency 2.

[0061] S302. Determine the minimum in-phase time interval between the echo signal corresponding to the secondary characteristic frequency and the echo signal corresponding to the central frequency according to the frequency difference.

[0062] If other frequency differences except the minimum frequency difference are integer multiples of the minimum frequency difference, then the reciprocal of the minimum frequency difference is taken as the minimum in-phase time interval. For example, if frequency difference 1 is equal to 100 Hz and frequency difference 2 is equal to 200 Hz, then 1 / 100 Hz = 10 ms can be taken as the minimum in-phase time interval.

[0063] If frequency difference 1 is 150 Hz and frequency difference 2 is 200 Hz, then the greatest common divisor 50 Hz can be used to calculate the minimum in-phase time interval, that is, the minimum in-phase time interval is equal to 1 / 50 = 20 ms. So there should be three cases when combining frequency differences pairwise: integer multiple, greatest common divisor not equal to 1, and greatest common divisor equal to 1.

[0064] The specific method for calculating the minimum in-phase time interval may also include:

[0065] When calculating the minimum in-phase time interval for multiple characteristic frequencies, the integer multiple should be judged first, and then the greatest common divisor. Take 2 frequencies each time to calculate the in-phase moment, and then compare with the remaining frequencies in turn according to the in-phase moment to determine whether to update the in-phase moment, where the in-phase moment refers to the minimum in-phase time interval.

[0066] For example: The process of finding the minimum in-phase time interval of frequency differences A = 695 Hz, B = 111 Hz, C = 222 Hz, and D = 192 Hz is as follows:

[0067] 1. It is found that there is an integer multiple relationship between frequency differences B and C, and B is used to represent C (B has a longer in-phase time). At this time, the in-phase moment is 1 / 111 s;

[0068] 2. It is found that the greatest common divisor of frequency differences B and D is 3. Therefore, the in-phase moment of frequency differences B and D is 1 / 3 s = 333.3 ms;

[0069] 3. The greatest common divisor of frequency difference A and 3 Hz is 1. Therefore, the in-phase moment of all 4 frequencies is 1000 / 695 ms * 333.3 ms = 479.57 ms.

[0070] It can also be seen from the above description that the more frequencies need to be considered, the longer the minimum in-phase time interval, the more obvious the T2* relaxation, the more obvious the intensity difference between the two echoes, and the signal-to-noise ratio of the second echo may be so low that the B0 information cannot be resolved from its phase.

[0071] In this embodiment, by determining the frequency difference between the central frequency and the secondary characteristic frequency, and determining the minimum in-phase time interval between the echo signal corresponding to the secondary characteristic frequency and the echo signal corresponding to the central frequency according to the frequency difference. Since the frequency difference can characterize the chemical shift between characteristic tissues, this embodiment determines the minimum in-phase time interval by considering the chemical shift between characteristic tissues during actual imaging. Furthermore, based on the minimum in-phase time interval, an accurate target echo time interval can be determined. The determined target echo time interval is more in line with the actual imaging situation, largely excluding the influence of chemical shift, improving the active shimming effect, and enhancing the quality of magnetic resonance imaging.

[0072] Referring to Figure 4 , Figure 4 is a schematic flowchart of a method for determining a frequency difference provided by an embodiment of the present application. This embodiment relates to an optional implementation manner of how to determine the frequency difference between the central frequency and the secondary characteristic frequency. On the basis of the above embodiment, the above S301 may include the following steps:

[0073] S401. Determine the target secondary characteristic frequency whose relative intensity is greater than or equal to the first threshold.

[0074] Referring to Figure 5 , Figure 5 is one of the schematic diagrams of the frequency spectrum provided by an embodiment of the present application. To more clearly introduce this embodiment in combination with the frequency spectrum, extract the characteristic frequencies greater than the first threshold in Figure 5 to obtain the schematic diagram of the frequency spectrum as shown in Figure 6 . Figure 6 is the second schematic diagram of the frequency spectrum provided by an embodiment of the present application. Figure 5 , Figure 6 The ordinate in

[0075] represents the relative intensity of the echo signal, and the abscissa represents the frequency, with the unit of Hz. Figure 5 , Figure 6 For example, if the first threshold is the ordinate value corresponding to the dashed line in Figure 5 , Figure 6 , there are a total of 2 secondary characteristic frequencies whose relative intensity is greater than or equal to the first threshold, that is, there are a total of 2 target secondary characteristic frequencies. Then, as shown in Figure 6 , there are a total of 2 target secondary characteristic frequencies whose relative intensity is above the dashed line. These 2 target secondary characteristic frequencies are the target secondary characteristic frequency 601 and the target secondary characteristic frequency 602 shown in

[0076] Since the smaller the frequency difference and / or the more the secondary characteristic frequencies to be considered, the longer the minimum in-phase time interval, resulting in more obvious T2* relaxation, more severe signal attenuation, lower signal-to-noise ratio, and inaccurate B0 field map obtained. Therefore, in this embodiment, in order to obtain a more accurate B0 field map, the secondary characteristic frequencies with relative intensity greater than or equal to the first threshold are selected as the target secondary characteristic frequencies, that is, the number of selected secondary characteristic frequencies is reduced, avoiding the problem of inaccurate B0 field map caused by the relatively long calculated minimum in-phase time interval, further improving the accuracy of the obtained B0 field map, thereby further improving the active shimming effect and enhancing the magnetic resonance imaging quality.

[0077] S402. Calculate the respective frequency differences between each target secondary characteristic frequency and the center frequency.

[0078] In this embodiment, by determining the secondary characteristic frequencies with relative intensity greater than or equal to the first threshold as the target secondary characteristic frequencies, the problem of inaccurate B0 field map caused by the relatively long calculated minimum in-phase time interval is avoided, further improving the accuracy of the obtained B0 field map, thereby further improving the active shimming effect and enhancing the magnetic resonance imaging quality.

[0079] Refer to Figure 7 , Figure 7 is a schematic flowchart of another method for determining the target echo time interval provided by an embodiment of the present application. This embodiment relates to an optional implementation manner of how to determine the target echo time interval based on the preset echo time interval and the minimum in-phase time interval. On the basis of the above embodiment, the above S202 may include the following steps:

[0080] S701. Determine the first candidate echo time interval according to the preset echo time interval and the minimum in-phase time interval.

[0081] Among them, S701. Determining the first candidate echo time interval according to the preset echo time interval and the minimum in-phase time interval can be implemented in the following manner:

[0082] If the minimum in-phase time interval is not less than the preset echo time interval, then use the minimum in-phase time interval as the first candidate echo time interval;

[0083] Or, if the minimum in-phase time interval is less than the preset echo time interval, then determine the smallest integer multiple of the minimum in-phase time interval as the first candidate echo time interval; where the smallest integer multiple of the minimum in-phase time interval is greater than the preset echo time interval.

[0084] S702. Determine the intensity ratio of two adjacent echo signals at the first candidate echo time interval according to the first candidate echo time interval and the apparent transverse magnetization vector relaxation time constant.

[0085] The apparent transverse magnetization vector relaxation time constant, i.e., the time constant of T2* relaxation. If A represents the intensity ratio and the first candidate echo time interval is represented by Δt, then

[0086] S703. If the intensity ratio is greater than the second threshold, the target echo time interval is determined according to the first candidate echo time interval.

[0087] Among them, S703. If the intensity ratio is greater than the second threshold, the target echo time interval is determined according to the first candidate echo time interval, which can be implemented in the following way:

[0088] If the intensity ratio is greater than the second threshold, the first candidate echo time interval is used as the target echo time interval.

[0089] In this embodiment, the first candidate echo time interval is determined according to the preset echo time interval and the minimum in-phase time interval, and the intensity ratio between two adjacent echo signals at the first candidate echo time interval is determined according to the first candidate echo time interval and the apparent transverse magnetization vector relaxation time constant. When the intensity ratio is greater than the second threshold, the target echo time interval is determined according to the first candidate echo time interval. Since the target echo time interval is further determined according to the intensity ratio, a B0 field map with a higher signal-to-noise ratio can be ensured, thereby improving the effect of active shimming based on the B0 field map and improving the quality of magnetic resonance imaging.

[0090] Optionally, on the basis of the above embodiment, the following steps may further be included:

[0091] If the intensity ratio is less than or equal to the second threshold, the target sub-feature frequency with the minimum relative intensity is removed, and the step of returning to execute the calculation of the minimum in-phase time interval between the echo signal corresponding to the remaining target sub-feature frequency and the echo signal corresponding to the center frequency to obtain a new intensity ratio is performed until the obtained new intensity ratio is greater than the second threshold;

[0092] The first candidate echo time interval corresponding to the target intensity ratio is used as the target echo time interval, where the target intensity ratio is the new intensity ratio greater than the second threshold.

[0093] In this embodiment, when the intensity ratio is less than or equal to the second threshold, the target sub-feature frequency with the minimum relative intensity is removed. For example, as Figure 6 shown, if based on Figure 6The intensity ratio calculated from the target secondary characteristic frequency 1 corresponding to the target secondary characteristic frequency 601 and the target secondary characteristic frequency 2 corresponding to the target secondary characteristic frequency 602 in is less than the second threshold. If the relative intensity of the target secondary characteristic frequency 2 is less than the relative intensity of the target secondary characteristic frequency 1, then the target secondary characteristic frequency 2 is removed, and the minimum in-phase time interval is calculated based on the frequency difference between the target secondary characteristic frequency 1 and the center frequency. Then, a new intensity ratio is calculated based on this minimum in-phase time interval. If this new intensity ratio is greater than the second threshold, the first candidate echo time interval corresponding to this new intensity ratio is used as the target echo time interval. Since when the intensity ratio is less than or equal to the second threshold, it indicates that there will be a relatively obvious intensity attenuation in the second echo at this time, and T2* relaxation should be considered first. When considering T2* relaxation first, the relative intensities of the previously obtained target secondary characteristic frequencies are sorted, and the target secondary characteristic frequency with the weakest relative intensity is removed to reduce the influence of T2* relaxation on the signal-to-noise ratio of the B0 field map. And the remaining target secondary characteristic frequencies are used to recalculate the minimum in-phase time interval until the new intensity ratio is greater than the second threshold.

[0094] In one embodiment, the above S703, if the intensity ratio is greater than the second threshold, then determining the target echo time interval according to the first candidate echo time interval can also be implemented in the following manner:

[0095] If the intensity ratio is greater than the second threshold, then determine the target echo time interval according to the current working mode of the magnetic resonance system and the first candidate echo time interval.

[0096] The working modes of the magnetic resonance system can include, for example, three modes: "signal-to-noise ratio priority mode", "structural image suppression priority mode", and "balanced mode". The working mode of the magnetic resonance system can be set manually or according to the algorithm scenario. For example, when the detected signal-to-noise ratio is low, the "signal-to-noise ratio priority mode" is used; when the signal-to-noise ratio is high, the "structural image suppression priority mode" is used; and the rest are set to the "balanced mode".

[0097] In this embodiment, when the intensity ratio is greater than the second threshold, the target echo time interval is determined according to the current working mode of the magnetic resonance system and the first candidate echo time interval, so that the determined target echo time interval is adapted to the current working mode of the magnetic resonance system, so that the determined target echo time interval can reflect the actual imaging situation, largely eliminate the influence of chemical shift, and then improve the active shimming effect and the quality of magnetic resonance imaging.

[0098] Refer to Figure 8 , Figure 8It is a schematic flowchart of yet another method for determining the target echo time interval provided by an embodiment of the present application. This embodiment relates to an alternative implementation manner of how to determine the target echo time interval according to the working mode of the current magnetic resonance system and the first candidate echo time interval when the intensity ratio is greater than the second threshold. Based on the above embodiment, the method may include the following steps:

[0099] S801. If the current working mode of the magnetic resonance system is the first mode or the second mode, reduce the first threshold, and based on the reduced first threshold, determine a new target sub-feature frequency, and return to execute the step of calculating the minimum in-phase time interval between the echo signal of the new target sub-feature frequency and the echo signal of the center frequency to obtain a new intensity ratio until the newly obtained intensity ratio in the current iteration is less than the second threshold.

[0100] Among them, the first mode is, for example, "signal-to-noise ratio priority mode", and the second mode is, for example, "structural image suppression priority mode". Or the first mode is "structural image suppression priority mode", and the second mode is "signal-to-noise ratio priority mode".

[0101] In this embodiment, if the first thresholds included in the preset first threshold list are 0.9, 0.7, and 0.5 respectively, and the second thresholds included in the preset second threshold list are 0.8, 0.6, and 0.4 respectively. If the current working mode of the magnetic resonance system is "signal-to-noise ratio priority mode", the initial value of the first threshold is set to the maximum value 0.9 in the first threshold list, and the initial value of the second threshold is set to the maximum value 0.8 in the second threshold list for analysis. Here, the process of reducing the first threshold is called the first iteration process, and the first iteration process is as follows:

[0102] 1. If the calculated intensity ratio is greater than the second threshold, reduce the first threshold. For example, reduce the first threshold from 0.9 to 0.7, and keep the second threshold unchanged.

[0103] 2. Then calculate the minimum in-phase time interval between the echo signal of the new target sub-feature frequency and the echo signal of the center frequency when the first threshold is equal to 0.7 and the second threshold is equal to 0.8 to obtain a new intensity ratio. If the newly obtained intensity ratio at this time is greater than the second threshold, continue to reduce the first threshold. For example, reduce the first threshold from 0.7 to 0.5, and keep the second threshold unchanged.

[0104] 3. Next, calculate the minimum in-phase time interval between the echo signal of the new target sub-feature frequency and the echo signal of the center frequency when the first threshold is equal to 0.5 and the second threshold is equal to 0.8, so as to obtain a new intensity ratio. If the obtained new intensity ratio is less than the second threshold, then use the first candidate echo time interval corresponding to the intensity ratio obtained when the first threshold is equal to 0.7 and the second threshold is equal to 0.8 as the target echo time interval. If the obtained new intensity ratio is greater than the second threshold at this time, and the minimum in-phase time intervals corresponding to each first threshold in the first threshold list have been calculated, then stop reducing the first threshold, and use the first candidate echo time interval corresponding to the new intensity ratio calculated in the current time as the target echo time interval.

[0105] S802. Use the first candidate echo time interval corresponding to the intensity ratio obtained in the previous time as the target echo time interval.

[0106] In this embodiment, by performing the steps of: if the current working mode of the magnetic resonance system is the first mode or the second mode, then reducing the first threshold, and determining a new target sub-feature frequency based on the reduced first threshold, and returning to execute the calculation of the minimum in-phase time interval between the echo signal of the new target sub-feature frequency and the echo signal of the center frequency, so as to obtain a new intensity ratio, until the new intensity ratio obtained in the current time is less than the second threshold, and using the first candidate echo time interval corresponding to the intensity ratio obtained in the previous time as the target echo time interval. By reducing the first threshold, more target sub-feature frequencies can be determined while ensuring the signal-to-noise ratio, thereby considering the influence of chemical shift more, and making the obtained B0 field map more accurate.

[0107] In one of the embodiments, the following steps may further be included:

[0108] If the new intensity ratio obtained in the current time is greater than or equal to the second threshold, and the stop condition for reducing the first threshold is satisfied, then stop reducing the first threshold, and use the first candidate echo time interval corresponding to the new intensity ratio obtained in the current time as the target echo time interval.

[0109] In this embodiment, the stop condition may be the last threshold traversed in the first threshold list when performing the first iteration process. Alternatively, the first threshold is reduced step by step according to a preset step. For example, the initial value of the first threshold is 0.9 and the preset reduction step is 0.1. In this case, when reducing the first threshold, the first threshold can be reduced by 0.1 each time. In this case, the stop condition may be a preset threshold for the number of reduction times. For example, if the threshold for the number of reduction times is equal to 5, the first threshold will be reduced at most 5 times. If the new intensity ratio obtained after 5 reductions is still greater than or equal to the second threshold, the first threshold will no longer be reduced, and the first candidate echo time interval corresponding to the new intensity ratio obtained in the current iteration will be used as the target echo time interval. That is, the first candidate echo time interval corresponding to the new intensity ratio when the first threshold is equal to 0.4 will be used as the target echo time interval.

[0110] Referring to Figure 9 , Figure 9 FIG. is a schematic flowchart of another method for determining the target echo time interval provided by an embodiment of the present application. This embodiment relates to an optional implementation manner of how to determine the target echo time interval according to the working mode of the current magnetic resonance system and the first candidate echo time interval. On the basis of the above embodiment, the method may include the following steps:

[0111] S901. If the current working mode of the magnetic resonance system is in the third mode, perform the first iteration operation; the first iteration operation includes: reducing the first threshold, and based on the reduced first threshold, determining a new target sub-feature frequency, and returning to perform the step of calculating the minimum in-phase time interval between the echo signal of the new target sub-feature frequency and the echo signal of the center frequency to obtain a new intensity ratio, until the new intensity ratio obtained in the current iteration is less than the second threshold, and using the first candidate echo time interval corresponding to the intensity ratio obtained in the previous iteration as the second candidate echo time interval.

[0112] It should be noted that the first iteration operation in this step may refer to the above first iteration process and will not be elaborated here.

[0113] Among them, the third mode may be an "equilibrium mode", and the equilibrium mode is, for example, a mode between the "signal-to-noise ratio priority mode" and the "structural image suppression priority mode". The first iteration operation is, for example, the process of reducing the first threshold in the above embodiment. For example, the first candidate echo time interval corresponding to the intensity ratio obtained in the previous iteration is the first candidate echo time interval when the first threshold is equal to 0.7 and the second threshold is equal to 0.8, and the first candidate echo time interval when the first threshold is equal to 0.7 and the second threshold is equal to 0.8 is used as the second candidate echo time interval corresponding to the second threshold equal to 0.8.

[0114] S902. According to the preset reduction rule, reduce the second threshold, and based on the reduced second threshold, return to perform the first iterative operation to calculate the second candidate echo time intervals corresponding to each reduced second threshold.

[0115] Among them, the process of reducing the second threshold can be called the second iterative process, and the second iterative process is as follows:

[0116] For example, the preset reduction rule is to reduce the second threshold according to a preset step. For example, the preset step is 0.2, then the second threshold can be reduced from 0.8 to 0.6, and the above-mentioned first iterative operation is re-executed, that is, the initial value of the first threshold is recalculated to be equal to 0.9, and the first iterative operation when the second threshold is equal to 0.6 is performed, and then the second candidate echo time interval corresponding to the second threshold equal to 0.6 is calculated.

[0117] It should be noted that the stop condition for reducing the second threshold can be similar to the stop condition for reducing the first threshold mentioned above, and will not be elaborated here.

[0118] S903. Determine the target echo time interval according to each second candidate echo time interval.

[0119] In this step, any one of the second candidate echo time intervals can be used as the target echo time interval. Or, the second candidate echo time interval corresponding to the second largest threshold (such as 0.6) is always used as the target echo time interval. Or, the user is allowed to select a time interval from each second candidate echo time interval as the target echo time interval through a drop-down box or a slider, etc.

[0120] In this embodiment, by reducing the second threshold according to the preset reduction rule, and based on the reduced second threshold, returning to perform the first iterative operation to calculate the second candidate echo time intervals corresponding to each reduced second threshold, and determining the target echo time interval according to each second candidate echo time interval, the target echo time interval with the best structural image suppression effect can be determined under multiple different second thresholds.

[0121] Refer to Figure 10 , Figure 10 is a schematic flowchart of a method for determining a frequency difference provided by an embodiment of the present application. This embodiment relates to an optional implementation manner of how to determine the frequency difference between the center frequency and the sub-feature frequency. On the basis of the above embodiment, the method may include the following steps:

[0122] S1001. Determine the target sub-feature frequency whose relative intensity is greater than or equal to the first threshold.

[0123] S1002. If the operating mode of the magnetic resonance system is in the fourth mode, determine the frequency difference between the center frequency and the target sub - characteristic frequency with the largest relative intensity; or, if the operating mode of the magnetic resonance system is in the fifth mode, calculate the respective frequency differences between each target sub - characteristic frequency and the center frequency.

[0124] Among them, the fourth mode is, for example, the "signal - to - noise ratio priority mode". In the "signal - to - noise ratio priority mode", only one sub - characteristic frequency with the highest relative intensity except the center frequency can be selected, and this sub - characteristic frequency with the highest relative intensity is used as the target sub - characteristic frequency, and the frequency difference between the center frequency and this target sub - characteristic frequency is calculated.

[0125] When the fifth mode is, for example, the "structural image suppression priority mode", the second threshold can be ignored, and all sub - characteristic frequencies that satisfy being greater than or equal to the first threshold are selected as target sub - characteristic frequencies, and the respective frequency differences between each target sub - characteristic frequency and the center frequency are calculated.

[0126] For a more clear and complete description of the echo interval determination method provided in this embodiment, the above - mentioned Figure 6 is introduced here.

[0127] Figure 6 The frequency spectrum line in is the frequency spectrum line collected under a 5T magnetic field strength. After frequency calibration, the center frequency is at 0 frequency, where 0 frequency means the place with a frequency of 0. The frequency difference between the target sub - characteristic frequencies corresponding to other tissue components and the center frequency is called the frequency difference.

[0128] According to the preset first threshold, the first threshold is, for example, equal to 0.4, and the target sub - characteristic frequencies in the frequency spectrum line with a relative intensity greater than the first threshold are screened. Take the centroid position of the target sub - characteristic frequencies on the virtual line corresponding to the first threshold, and the frequency differences and relative intensities corresponding to the two target sub - characteristic frequencies can be obtained, that is, the frequency difference 1 between the target sub - characteristic frequency 1 corresponding to the target sub - characteristic frequency 601 and the center frequency and the relative intensity 1 of the target sub - characteristic frequency 1, and the frequency difference 2 between the target sub - characteristic frequency 2 corresponding to the target sub - characteristic frequency 602 and the center frequency and the relative intensity 2 of the target sub - characteristic frequency 1 are obtained. Suppose the two frequency differences are - 695Hz and 192Hz respectively, and the two relative intensities are 0.594 and 0.457 respectively. Then the minimum in - phase time interval for making the characteristic tissues corresponding to these three characteristic frequencies in - phase is Δt = 1 / 695 * 1 / 192 = 7.49ms.

[0129] If the minimum time interval Δt is greater than or equal to the preset echo time interval, then use this Δt as the first candidate echo time interval. If the minimum time interval Δt is less than the preset echo time interval, then use the smallest integer multiple of Δt as the first candidate echo time interval, where the smallest integer multiple of Δt is greater than or equal to the preset echo time interval.

[0130] Here, it is assumed that the minimum time interval Δt is greater than or equal to the preset echo time interval. Then, according to the preset second threshold (for example, the second threshold is equal to 0.5), it is judged whether the intensity ratio of the second echo to the first echo at the first candidate echo time interval is large enough (a small intensity ratio indicates that the signal intensity has significantly decayed when collecting the second echo, which is not conducive to obtaining the B0 field map using the phase difference). If the T2* relaxation time constant obtained at this time is 20 ms, it can be known that the intensity ratio at this first candidate echo time interval is If this intensity ratio is greater than the second threshold, it indicates that after comprehensively considering the inaccuracy of the B0 field map caused by T2* relaxation and the structural image caused by chemical shift, chemical shift should be given priority, and 7.49 ms is selected as the target echo time interval for the B0 field map; if the T2* obtained at this time is 7 ms, the intensity ratio is Less than the second threshold, indicating that there will be a relatively obvious intensity decay in the second echo at this time. At this time, T2* relaxation should be given priority. When giving priority to T2* relaxation, sort the previously obtained relative intensities, remove the target sub-feature frequency with the weakest relative intensity, and recalculate Δt using the remaining target sub-feature frequencies until the intensity ratio is greater than the second threshold.

[0131] Refer to Figure 11 , Figure 11 is a schematic diagram of a method for implementing a B0 field map provided by an embodiment of the present application. Among them, the target echo time interval is set to the smallest positive integer multiple of the minimum in-phase time interval Δt, and the target echo time interval is greater than the preset echo time interval, so that the B0 field map not affected by chemical shift can be obtained by using the phase difference of the two echoes. For example, the preset echo time interval is equal to the shortest time interval supported by the magnetic resonance system, and the shortest time interval is equal to 2 ms. The obtained Δt = 1.5 ms. Since Δt = 1.5 ms is less than 2 ms, the finally set target echo time interval = 1.5 * 2 = 3 ms. Figure 11 The dTE shown in Figure 11 represents the target echo time interval.

[0132] It should be understood that although the steps in the flowcharts involved in the above embodiments are shown in sequence according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless there is a clear indication 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 flowcharts involved in the above embodiments may include multiple steps or multiple stages. These steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be executed alternately or in turn with at least a part of other steps or steps or stages in other steps.

[0133] Based on the same inventive concept, an embodiment of the present application also provides an echo interval determination device for implementing the echo interval determination method described above. The implementation solutions provided by this device to solve problems are similar to those described in the above method. Therefore, the specific limitations in one or more embodiments of the echo interval determination device provided below can refer to the limitations on the echo interval determination method in the above text and will not be repeated here.

[0134] In one embodiment, as Figure 12 shown, Figure 12 is a schematic structural diagram of an echo interval determination device provided by an embodiment of the present application, including: an extraction module 1201 and a first determination module 1202, where:

[0135] The extraction module 1201 is used to extract the characteristic frequencies of each characteristic tissue from the frequency spectrum line of the echo signal of the sample to be tested; wherein, the frequency spectrum line includes the characteristic frequencies of at least one characteristic tissue of the sample to be tested;

[0136] The first determination module 1202 is used to determine the target echo time interval between two adjacent echo signals that need to be set based on the extracted characteristic frequencies and a preset echo time interval.

[0137] In one of the embodiments, the first determination module 1202 is specifically configured to use the preset echo time interval as the target echo time interval if the total number of the extracted characteristic frequencies is one.

[0138] In one of the embodiments, the first determination module 1202 includes:

[0139] The first determination unit is used to determine the minimum in-phase time interval between the echo signal corresponding to the sub-characteristic frequency and the echo signal corresponding to the center frequency among the multiple characteristic frequencies if the total number of the extracted characteristic frequencies is multiple;

[0140] A second determination unit, configured to determine the target echo time interval based on the preset echo time interval and the minimum in-phase time interval.

[0141] In one embodiment, the first determination unit includes:

[0142] A first determination subunit, configured to determine the frequency difference between the center frequency and the sub-feature frequency;

[0143] A second determination subunit, configured to determine the minimum in-phase time interval between the echo signal corresponding to the sub-feature frequency and the echo signal corresponding to the center frequency according to the frequency difference.

[0144] In one embodiment, the first determination subunit is specifically configured to determine the target sub-feature frequencies whose relative intensities are greater than or equal to a first threshold; and calculate the respective frequency differences between each target sub-feature frequency and the center frequency.

[0145] In one embodiment, the second determination unit includes:

[0146] A third determination subunit, configured to determine a first candidate echo time interval according to the preset echo time interval and the minimum in-phase time interval;

[0147] A fourth determination subunit, configured to determine the intensity ratio between two adjacent echo signals at the first candidate echo time interval according to the first candidate echo time interval and the apparent transverse magnetization vector relaxation time constant;

[0148] A fifth determination subunit, configured to, if the intensity ratio is greater than a second threshold, determine the target echo time interval according to the first candidate echo time interval.

[0149] In one embodiment, the third determination subunit is specifically configured to, if the minimum in-phase time interval is not less than the preset echo time interval, use the minimum in-phase time interval as the first candidate echo time interval; or, if the minimum in-phase time interval is less than the preset echo time interval, determine the minimum integer multiple of the minimum in-phase time interval as the first candidate echo time interval, where the minimum integer multiple of the minimum in-phase time interval is greater than the preset echo time interval.

[0150] In one embodiment, the fifth determination subunit is specifically configured to, if the intensity ratio is greater than the second threshold, use the first candidate echo time interval as the target echo time interval.

[0151] In one embodiment, the fifth determination subunit is specifically configured to, if the intensity ratio is greater than the second threshold, determine the target echo time interval according to the current working mode of the magnetic resonance system and the first candidate echo time interval.

[0152] In one embodiment, the fifth determination subunit is specifically configured to, if the current working mode of the magnetic resonance system is the first mode or the second mode, reduce the first threshold, and based on the reduced first threshold, determine a new target sub-feature frequency, and return to execute the step of calculating the minimum in-phase time interval between the echo signal of the new target sub-feature frequency and the echo signal of the center frequency to obtain a new intensity ratio, until the newly obtained intensity ratio in the current time is less than the second threshold; use the first candidate echo time interval corresponding to the intensity ratio obtained in the previous time as the target echo time interval.

[0153] In one embodiment, the fifth determination subunit is further configured to, if the newly obtained intensity ratio in the current time is greater than or equal to the second threshold and the stop condition for reducing the first threshold is satisfied, stop reducing the first threshold, and use the first candidate echo time interval corresponding to the newly obtained intensity ratio in the current time as the target echo time interval.

[0154] In one embodiment, the fifth determination subunit is specifically configured to, if the current working mode of the magnetic resonance system is in the third mode, perform a first iteration operation; the first iteration operation includes: reducing the first threshold, and based on the reduced first threshold, determine a new target sub-feature frequency, and return to execute the step of calculating the minimum in-phase time interval between the echo signal of the new target sub-feature frequency and the echo signal of the center frequency to obtain a new intensity ratio, until the newly obtained intensity ratio in the current time is less than the second threshold, and use the first candidate echo time interval corresponding to the intensity ratio obtained in the previous time as the second candidate echo time interval; according to a preset reduction rule, reduce the second threshold, and based on the reduced second threshold, return to execute the first iteration operation to calculate the second candidate echo time interval corresponding to each reduced second threshold; determine the target echo time interval according to each of the second candidate echo time intervals.

[0155] In one embodiment, the fifth determination subunit is further configured to, if the intensity ratio is less than or equal to the second threshold, remove the target sub-feature frequency with the minimum relative intensity, and return to execute the step of calculating the minimum in-phase time interval between the echo signal corresponding to the remaining target sub-feature frequency and the echo signal corresponding to the center frequency until the obtained new intensity ratio is greater than the second threshold; use the first candidate echo time interval corresponding to the target intensity ratio as the target echo time interval, where the target intensity ratio is the new intensity ratio greater than the second threshold.

[0156] In one embodiment, the first determination subunit is specifically configured to determine the sub-feature frequency with a relative intensity greater than or equal to the first threshold as the target sub-feature frequency; if the working mode of the magnetic resonance system is in the fourth mode, determine the frequency difference between the center frequency and the target sub-feature frequency with the maximum relative intensity; or, if the working mode of the magnetic resonance system is in the fifth mode, calculate the respective frequency differences between each target sub-feature frequency and the center frequency.

[0157] Each module in the above echo interval determination device can be implemented in whole or in part by software, hardware, and their combination. The above modules can be embedded in the processor in the computer device in hardware form or be independent of it, or can be stored in the memory in the computer device in software form so that the processor can call and execute the operations corresponding to the above modules.

[0158] In one embodiment, a computer device is provided. The computer device can be a server, and its internal structure diagram can be as Figure 13 shown Figure 13 which is the internal structure diagram of the computer device in one embodiment. The computer device includes a processor, a memory, and a network interface 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, a computer program, and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store the determination data of the echo interval. The network interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, it implements a method for determining an echo interval.

[0159] Those skilled in the art can understand Figure 13The structure shown 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. Specifically, the computer device may include more or fewer components than those shown in the figure, or combine some components, or have different component arrangements.

[0160] 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:

[0161] Extract the characteristic frequencies of each characteristic tissue from the frequency spectrum line of the echo signal of the sample to be inspected; wherein, the frequency spectrum line includes the characteristic frequencies of at least one characteristic tissue of the sample to be inspected;

[0162] Based on the extracted characteristic frequencies and a preset echo time interval, determine the target echo time interval between two adjacent echo signals that need to be set.

[0163] In one embodiment, when the processor executes the computer program, the following steps are further implemented:

[0164] If the total number of the extracted characteristic frequencies is one, use the preset echo time interval as the target echo time interval.

[0165] In one embodiment, when the processor executes the computer program, the following steps are further implemented:

[0166] If the total number of the extracted characteristic frequencies is multiple, based on the multiple characteristic frequencies, determine the minimum in-phase time interval between the echo signal corresponding to the secondary characteristic frequency and the echo signal corresponding to the center frequency among the multiple characteristic frequencies;

[0167] Based on the preset echo time interval and the minimum in-phase time interval, determine the target echo time interval.

[0168] In one embodiment, when the processor executes the computer program, the following steps are further implemented:

[0169] Determine the frequency difference between the center frequency and the secondary characteristic frequency;

[0170] According to the frequency difference, determine the minimum in-phase time interval between the echo signal corresponding to the secondary characteristic frequency and the echo signal corresponding to the center frequency.

[0171] In one embodiment, when the processor executes the computer program, the following steps are further implemented:

[0172] Determine the secondary characteristic frequencies with relative intensity greater than or equal to the first threshold as the target secondary characteristic frequencies;

[0173] Calculate each frequency difference between each target sub-feature frequency and the center frequency respectively.

[0174] In one embodiment, when the processor executes the computer program, the following steps are further implemented:

[0175] Determine a first candidate echo time interval according to the preset echo time interval and the minimum in-phase time interval;

[0176] Determine the intensity ratio of two adjacent echo signals at the first candidate echo time interval according to the first candidate echo time interval and the apparent transverse magnetization vector relaxation time constant;

[0177] If the intensity ratio is greater than a second threshold, determine the target echo time interval according to the first candidate echo time interval.

[0178] In one embodiment, when the processor executes the computer program, the following steps are further implemented:

[0179] If the minimum in-phase time interval is not less than the preset echo time interval, use the minimum in-phase time interval as the first candidate echo time interval;

[0180] Or, if the minimum in-phase time interval is less than the preset echo time interval, determine the minimum integer multiple of the minimum in-phase time interval as the first candidate echo time interval; wherein, the minimum integer multiple of the minimum in-phase time interval is greater than the preset echo time interval.

[0181] In one embodiment, when the processor executes the computer program, the following steps are further implemented:

[0182] If the intensity ratio is greater than the second threshold, use the first candidate echo time interval as the target echo time interval.

[0183] In one embodiment, when the processor executes the computer program, the following steps are further implemented:

[0184] If the intensity ratio is greater than the second threshold, determine the target echo time interval according to the current working mode of the magnetic resonance system and the first candidate echo time interval.

[0185] In one embodiment, when the processor executes the computer program, the following steps are further implemented:

[0186] If the current working mode of the magnetic resonance system is the first mode or the second mode, then reduce the first threshold, and based on the reduced first threshold, determine a new target sub-feature frequency, and return to perform the step of calculating the minimum in-phase time interval between the echo signal of the new target sub-feature frequency and the echo signal of the center frequency to obtain a new intensity ratio, until the newly obtained intensity ratio in the current time is less than the second threshold;

[0187] Use the first candidate echo time interval corresponding to the intensity ratio obtained in the previous time as the target echo time interval.

[0188] In one embodiment, when the processor executes the computer program, the following steps are further implemented:

[0189] If the newly obtained intensity ratio in the current time is greater than or equal to the second threshold, and the stop condition for reducing the first threshold is satisfied, then stop reducing the first threshold, and use the first candidate echo time interval corresponding to the newly obtained intensity ratio in the current time as the target echo time interval.

[0190] In one embodiment, when the processor executes the computer program, the following steps are further implemented:

[0191] If the current working mode of the magnetic resonance system is in the third mode, then perform a first iterative operation; the first iterative operation includes: reducing the first threshold, and based on the reduced first threshold, determining a new target sub-feature frequency, and returning to perform the step of calculating the minimum in-phase time interval between the echo signal of the new target sub-feature frequency and the echo signal of the center frequency to obtain a new intensity ratio, until the newly obtained intensity ratio in the current time is less than the second threshold, and using the first candidate echo time interval corresponding to the intensity ratio obtained in the previous time as the second candidate echo time interval;

[0192] According to a preset reduction rule, reduce the second threshold, and based on the reduced second threshold, return to perform the first iterative operation to calculate the second candidate echo time interval corresponding to each reduced second threshold;

[0193] Determine the target echo time interval according to each of the second candidate echo time intervals.

[0194] In one embodiment, when the processor executes the computer program, the following steps are further implemented:

[0195] If the intensity ratio is less than or equal to the second threshold, then remove the target sub-feature frequency with the minimum relative intensity, and return to perform the step of calculating the minimum in-phase time interval between the echo signals corresponding to the remaining target sub-feature frequencies and the echo signal corresponding to the center frequency to obtain a new intensity ratio, until the newly obtained intensity ratio is greater than the second threshold;

[0196] Take the first candidate echo time interval corresponding to the target intensity ratio as the target echo time interval, where the target intensity ratio is a new intensity ratio greater than the second threshold.

[0197] In one embodiment, when the processor executes the computer program, the following steps are further implemented:

[0198] Determine the target sub-feature frequency whose relative intensity is greater than or equal to the first threshold;

[0199] If the operating mode of the magnetic resonance system is in the fourth mode, determine the frequency difference between the center frequency and the target sub-feature frequency with the maximum relative intensity; or, if the operating mode of the magnetic resonance system is in the fifth mode, calculate the respective frequency differences between each target sub-feature frequency and the center frequency.

[0200] 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 steps of the method for determining the echo interval in the above embodiment are implemented.

[0201] In one embodiment, a computer program product is provided, including a computer program. When the computer program is executed by a processor, the steps of the method for determining the echo interval in the above embodiment are implemented.

[0202] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties.

[0203] 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 methods. Among them, any reference to a memory, database, or other medium used in the embodiments provided in the present application can include at least one of non-volatile and volatile memories. Non-volatile memory can include Read-Only Memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc. The databases involved in the embodiments provided in the present application can include at least one of relational databases and non-relational databases. Non-relational databases can include distributed databases based on blockchain, etc., without limitation. The processors involved in the embodiments provided in the present application can be general-purpose processors, central processors, graphics processors, digital signal processors, programmable logic devices, data processing logics based on quantum computing, etc., without limitation.

[0204] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of 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.

[0205] The above-described embodiments merely represent several implementation manners of the present application. The description thereof is relatively specific and detailed, but it should not be construed as a limitation on 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 present application should be subject to the appended claims.

Claims

1. A method for determining an echo interval, characterized in that The method includes: extracting the characteristic frequencies of each characteristic tissue from the frequency spectrum line of the echo signal of the sample to be examined; wherein, the frequency spectrum line includes the characteristic frequencies of at least one characteristic tissue of the sample to be examined; determining a target echo time interval between two adjacent echo signals to be set based on the extracted characteristic frequencies and a preset echo time interval; The determining a target echo time interval between two adjacent echo signals to be set based on the extracted characteristic frequencies and a preset echo time interval includes: if the total number of the extracted characteristic frequencies is multiple, determining a minimum in-phase time interval between the echo signal corresponding to the secondary characteristic frequency and the echo signal corresponding to the central frequency among the multiple characteristic frequencies based on the multiple characteristic frequencies; determining the target echo time interval based on the preset echo time interval and the minimum in-phase time interval.

2. The method according to claim 1, characterized in that, The determining a target echo time interval between two adjacent echo signals to be set based on the extracted characteristic frequencies and a preset echo time interval includes: if the total number of the extracted characteristic frequencies is one, taking the preset echo time interval as the target echo time interval.

3. The method according to claim 1, wherein The determining a minimum in-phase time interval between the echo signal corresponding to the secondary characteristic frequency and the echo signal corresponding to the central frequency among the multiple characteristic frequencies based on the multiple characteristic frequencies includes: determining the frequency difference between the central frequency and the secondary characteristic frequency; determining the minimum in-phase time interval between the echo signal corresponding to the secondary characteristic frequency and the echo signal corresponding to the central frequency according to the frequency difference.

4. The method according to claim 3, characterized in that, The determining the frequency difference between the central frequency and the secondary characteristic frequency includes: determining the target secondary characteristic frequencies whose relative intensity is greater than or equal to a first threshold; calculating the respective frequency differences between each target secondary characteristic frequency and the central frequency.

5. The method according to claim 4, characterized in that, The determining the target echo time interval based on the preset echo time interval and the minimum in-phase time interval includes: determining a first candidate echo time interval according to the preset echo time interval and the minimum in-phase time interval; determining the intensity ratio of two adjacent echo signals at the first candidate echo time interval according to the first candidate echo time interval and the apparent transverse magnetization vector relaxation time constant; if the intensity ratio is greater than a second threshold, determining the target echo time interval according to the first candidate echo time interval.

6. The method according to claim 5, wherein The determining a first candidate echo time interval according to the preset echo time interval and the minimum in-phase time interval includes: if the minimum in-phase time interval is not less than the preset echo time interval, taking the minimum in-phase time interval as the first candidate echo time interval; or, if the minimum in-phase time interval is less than the preset echo time interval, determining the minimum integer multiple of the minimum in-phase time interval as the first candidate echo time interval; wherein, the minimum integer multiple of the minimum in-phase time interval is greater than the preset echo time interval.

7. The method according to claim 5, characterized in that The if the intensity ratio is greater than a second threshold, determining the target echo time interval according to the first candidate echo time interval includes: If the intensity ratio is greater than the second threshold, the first candidate echo time interval is used as the target echo time interval.

8. The method according to claim 5, characterized in that If the intensity ratio is greater than the second threshold, determining the target echo time interval according to the first candidate echo time interval includes: If the intensity ratio is greater than the second threshold, determining the target echo time interval according to the current working mode of the magnetic resonance system and the first candidate echo time interval.

9. The method according to claim 8, wherein Determining the target echo time interval according to the working mode of the current magnetic resonance system and the first candidate echo time interval includes: If the current working mode of the magnetic resonance system is the first mode or the second mode, the first threshold is reduced, and a new target sub-feature frequency is determined based on the reduced first threshold, and the step of returning to calculate the minimum in-phase time interval between the echo signal of the new target sub-feature frequency and the echo signal of the center frequency to obtain a new intensity ratio is executed until the newly obtained intensity ratio in the current iteration is less than the second threshold; The first candidate echo time interval corresponding to the intensity ratio obtained in the previous iteration is used as the target echo time interval.

10. The method according to claim 9, wherein The method further includes: If the newly obtained intensity ratio in the current iteration is greater than or equal to the second threshold and the stop condition for reducing the first threshold is satisfied, the reduction of the first threshold is stopped, and the first candidate echo time interval corresponding to the newly obtained intensity ratio in the current iteration is used as the target echo time interval.

11. The method according to claim 8, characterized in that, Determining the target echo time interval according to the working mode of the current magnetic resonance system and the first candidate echo time interval includes: If the current working mode of the magnetic resonance system is in the third mode, a first iterative operation is performed; the first iterative operation includes: reducing the first threshold, determining a new target sub-feature frequency based on the reduced first threshold, and returning to execute the step of calculating the minimum in-phase time interval between the echo signal of the new target sub-feature frequency and the echo signal of the center frequency to obtain a new intensity ratio until the newly obtained intensity ratio in the current iteration is less than the second threshold, and the first candidate echo time interval corresponding to the intensity ratio obtained in the previous iteration is used as the second candidate echo time interval; According to a preset reduction rule, the second threshold is reduced, and based on the reduced second threshold, the first iterative operation is returned to execute, and the second candidate echo time interval corresponding to each reduced second threshold is calculated; The target echo time interval is determined according to each of the second candidate echo time intervals.

12. The method according to claim 5, wherein The method further includes: If the intensity ratio is less than or equal to the second threshold, the target sub-feature frequency with the minimum relative intensity is removed, and the step of returning to calculate the minimum in-phase time interval between the echo signals corresponding to the remaining target sub-feature frequencies and the echo signal corresponding to the center frequency to obtain a new intensity ratio is executed until the newly obtained intensity ratio is greater than the second threshold; The first candidate echo time interval corresponding to the target intensity ratio is used as the target echo time interval, where the target intensity ratio is the new intensity ratio greater than the second threshold.

13. The method according to claim 3, characterized in that, Determining the frequency difference between the center frequency and the sub-feature frequencies includes: Determining the sub-feature frequencies with relative intensity greater than or equal to the first threshold as target sub-feature frequencies; If the working mode of the magnetic resonance system is in the fourth mode, determining the frequency difference between the center frequency and the target sub-feature frequency with the maximum relative intensity; or, if the working mode of the magnetic resonance system is in the fifth mode, calculating the respective frequency differences between each target sub-feature frequency and the center frequency.

14. An apparatus for determining an echo interval, characterized in that The device includes: An extraction module, configured to extract the feature frequencies of each feature tissue from the frequency spectrum line of the echo signal of the sample to be examined; wherein, the frequency spectrum line includes the feature frequencies of at least one feature tissue of the sample to be examined; A determination module, configured to determine the target echo time interval between two adjacent echo signals to be set based on the extracted feature frequencies and a preset echo time interval; The determining the target echo time interval between two adjacent echo signals to be set based on the extracted feature frequencies and a preset echo time interval includes: If the total number of the extracted feature frequencies is multiple, determining the minimum in-phase time interval between the echo signal corresponding to the sub-feature frequency and the echo signal corresponding to the center frequency among the multiple feature frequencies based on the multiple feature frequencies; Determining the target echo time interval based on the preset echo time interval and the minimum in-phase time interval.

15. 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 13 are implemented.

16. 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 13 are implemented.

17. A computer program product, comprising a computer program, 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 13 are implemented.

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