Electrocardio gating signal processing device and method used under nuclear magnetic resonance

Abstract

The invention discloses an electrocardio gating signal processing device and method used under nuclear magnetic resonance, and belongs to the technical field of nuclear magnetic resonance electrocardio gating processing.The method comprises the steps that an integrated circuit board of physical magnetic shielding collects superposed signals of electrocardio signals and nuclear magnetic noise, and the superposed signals serve as original electrocardio signals after noise filtering and amplification are conducted on the superposed signals in sequence; the method comprises the following steps: performing real-time frequency analysis on an original electrocardiosignal, extracting various electrocardiosignal characteristics, reconstructing a mask vector to filter noise and reconstruct a time-domain R-wave signal, reconstructing an electrocardiosignal based on the reconstructed time-domain R-wave signal and the various electrocardiosignal characteristics, detecting an R-wave trigger point based on the reconstructed electrocardiosignal and generating a gating signal, missed triggering and false triggering detection is carried out on R-wave triggering points in real time; and the reconstructed electrocardiosignal, the gating signal and various electrocardiosignal characteristics are output to a nuclear magnetic resonance system, and matching of different gating trigger conditions based on a magnetic resonance scanning sequence is supported, so that accurate positioning of R waves can be realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of nuclear magnetic resonance electrocardiogram gating processing, and in particular relates to an electrocardiogram gating signal processing device and method for nuclear magnetic resonance. Background Art

[0002] ECG Gated MRI is a technology that combines electrocardiogram (ECG) signals with magnetic resonance imaging (MRI) for synchronization, and is mainly used for the acquisition and analysis of cardiac images. The heart is constantly beating, which causes motion artifacts in conventional MRI imaging, affecting the quality of the image and the accuracy of the diagnosis. ECG gating technology can significantly improve the image quality and diagnostic accuracy by performing MRI imaging at specific moments in the cardiac cycle. ECG gating technology uses ECG signals to coordinate and synchronize the MRI scanner to ensure that image acquisition is performed at the stage when the heart moves the least. Specifically, the R wave in the ECG signal is used as a trigger signal because the R wave represents the starting stage of cardiac contraction and is relatively easy to detect. Based on the R wave signal, image acquisition can be performed at specific moments in the cardiac cycle (such as ventricular diastole), thereby reducing or eliminating cardiac motion artifacts.

[0003] Existing MRI ECG gating includes prospective gating and retrospective gating. Prospective gating: Image acquisition is performed after each R wave, and a fixed delay time is usually set to ensure that the acquisition is performed during a relatively still stage of the heart. This method is suitable for patients with stable heart rate and has a short imaging time, but cannot be used in cases of arrhythmia. Retrospective gating: ECG signals and MRI data are acquired simultaneously, and then the images are sorted and reconstructed according to the ECG signals in image post-processing. This method can capture images of the entire cardiac cycle and obtain cardiac images with high temporal resolution and spatial resolution, which is helpful for comprehensive analysis of cardiac function. It is widely used in cardiac function assessment, myocardial histology examination and pathological diagnosis, but the acquisition time is long. These two ECG gating technologies effectively reduce image artifacts caused by heart beating and significantly improve image quality and clarity. Clear cardiac images help evaluate the anatomical structure and functional status of the heart, and are especially suitable for the diagnosis of complex heart diseases such as cardiomyopathy and valvular heart disease.

[0004] Although the above-mentioned MRI ECG gating technology has significant advantages in improving the quality of cardiac imaging, it also has some technical difficulties and challenges. The main difficulties faced in practical applications include: 1. The strong magnetic field and radio frequency pulses in the MRI environment can cause significant interference to the ECG signal, especially in high-field MRI (such as 3.0T or higher). This interference may cause ECG signal distortion, affect the accurate detection of R waves, and further affect the accuracy of gate triggering. Since ECG electrodes and wires may generate artifacts or interference signals in the magnetic field, special design and shielding measures are required to reduce the impact of these interferences.

[0005] 2. For patients with arrhythmia or atrial fibrillation, the ECG signal is unstable and the R wave detection becomes more difficult. In this case, the ECG gating may not be triggered accurately, resulting in imaging failure or quality degradation. In some special cases (such as high or abnormally prominent T waves), the ECG gating system may mistakenly identify the T wave as an R wave, causing an erroneous trigger and affecting the accuracy of image acquisition.

[0006] 3. ECG gating technology requires real-time signal processing while collecting ECG signals to accurately identify the R wave and trigger it. The signal processing algorithm must complete the analysis in a short time, otherwise it will cause trigger delays, thus affecting image quality. For retrospective gating, the amount of MRI data collected is large, and the amount of calculation for subsequent data reconstruction and processing increases significantly, which places higher requirements on the system hardware performance. Summary of the invention

[0007] In view of the above, the purpose of the present invention is to provide an ECG gating signal processing device and method for nuclear magnetic resonance, so as to solve the problem in the related art that the ECG signal waveform is affected by magnetic resonance and produces a lot of noise and cannot accurately locate the R wave, and the problem that the R wave is difficult to locate due to the large difference in the individual physiological conditions of patients. The device and method of the present invention can be used for both prospective and retrospective ECG gating, and can adapt to ECG signal processing schemes for multiple sequence scans.

[0008] To achieve the above-mentioned purpose of the invention, an embodiment provides an ECG gating signal processing device for nuclear magnetic resonance, including an acquisition module, a calculation module, and a transmission module, which are all integrated on an integrated circuit board and are physically magnetically shielded; The acquisition module is used to acquire the superposition signal of the ECG signal and the nuclear magnetic noise under the physical magnetic shielding condition, and perform noise filtering and amplification on the superposition signal in sequence as the original ECG signal; The calculation module is used to perform real-time frequency analysis on the original ECG signal, extract various ECG signal features in the frequency domain, reconstruct the mask vector after the real-time frequency analysis to filter the noise and reconstruct the time-domain R-wave signal, reconstruct the ECG signal based on the reconstructed time-domain R-wave signal and various ECG signal features, detect the R-wave trigger point based on the reconstructed ECG signal and generate a gating signal, and also perform missed triggering and false triggering detection on the R-wave trigger point in real time; The transmission module is used to output the reconstructed ECG signal, gating signal and various ECG signal features to the nuclear magnetic resonance system, and supports matching different gating trigger conditions based on the magnetic resonance scanning sequence.

[0009] Preferably, the superimposed signal is subjected to noise filtering and amplification in sequence to obtain the original ECG signal, including: The superimposed signal collected by the integrated circuit board is first subjected to front-end RF and anti-aliasing hardware low-pass filtering to filter out RF and static magnetic field coupling interference, and then the filtered signal is enhanced by the back-end modulation and amplification circuit to obtain the original ECG signal and output it.

[0010] Preferably, the original ECG signal is subjected to real-time frequency analysis to extract various ECG signal features in the frequency domain, including: Perform real-time frequency analysis on the original ECG signal, convert the original ECG signal into the frequency domain to obtain a frequency domain signal, identify the main frequency of the ECG signal and the noise frequency of the nuclear magnetic noise based on the frequency domain signal in the frequency domain, and then retain the main frequency of the ECG signal to obtain a filtered signal; Multiple numerical calculations are performed on the original ECG signal and the filtered signal in the frequency domain to extract various ECG signal features, including ECG morphology features, heart rate features, signal amplitude features, ECG signal power spectrum density features, and QRS wave peak energy features.

[0011] Preferably, reconstructing the mask vector after real-time frequency analysis to filter noise and reconstruct the time domain R-wave signal comprises: After real-time frequency analysis, in the frequency domain, according to the main frequency of the identified ECG signal and the noise frequency of the nuclear magnetic noise, by comparing the clean ECG signal under normal ECG and the interference ECG signal under nuclear magnetic noise, the R wave frequency with the highest amplitude and the most significant ECG signal characteristics in the clean ECG signal is screened out as the R wave frequency center. Based on the R wave frequency center, a mask vector is constructed through the similarity criterion and under the constraint condition, wherein the constraint condition is to retain the ECG-related bands as much as possible and specifically eliminate the noise bands; According to the mask vector, a linear integration operation is performed on the frequency domain signal in the frequency domain, and after the noise frequency band is removed, it is converted to the time domain and reconstructed into the time domain R wave signal.

[0012] Preferably, detecting the R wave trigger point based on the reconstructed ECG signal and generating a gating signal comprises: Automatically record R wave signal related features based on the reconstructed ECG signal, wherein the R wave signal related features include R wave peak, R wave morphology, R wave frequency, RR interval, R wave slope, R wave abundance, related spectrum, and related power spectrum; Based on the relevant characteristics of the R wave signal, the R wave trigger point is detected and the gating signal is generated, including using a sliding window to perform weighted averaging on the relevant characteristics of the R wave signal in the window as the R wave trigger point threshold, and detecting the R wave signal that exceeds the R wave trigger point threshold as the R wave trigger point and generating a gating signal.

[0013] Preferably, the missed triggering and false triggering detection of the R wave trigger point is performed in real time, including: During the detection process, the missed triggering or false triggering of the R wave trigger point is judged in real time and dynamically. When a missed trigger or false trigger occurs, the error correction program is started to retrospectively correct the reconstructed ECG signal data. The R wave peak is matched with a higher R wave trigger point threshold in the stored data domain, the interference noise and the normal R wave peak are judged, and the R wave signal related features are updated with certain weights. According to the summarized R wave signal related features, especially the interfered R wave signal related features under noise, the next correct R wave trigger point is found.

[0014] Preferably, during data transmission, a gated trigger method is used to output the reconstructed ECG signal and the gated signal according to a predetermined sampling rate to trigger the gated signal; at the same time, the supported magnetic resonance scanning sequences include a customized prospective gated sequence and a retrospective gated sequence, and these two gated sequences match the customized gated trigger conditions to trigger the gated signal.

[0015] Preferably, in a nuclear magnetic resonance environment, a three-layer magnetic shield is used for the integrated circuit board of the front end to realize physical magnetic shielding, including: The integrated circuit board is covered with a non-magnetic shielding cover, and the integrated circuit board covered with the non-magnetic shielding cover is wrapped and shielded by an anti-magnetic shielding film, and then the integrated circuit board wrapped by the anti-magnetic shielding film is placed in a shielding box, so that the collected original electrocardiogram signal and the calculation and transmission processes of the electrocardiogram signal are protected by three layers of magnetic shielding.

[0016] To achieve the above-mentioned purpose of the invention, an embodiment further provides a method for processing ECG gating signals under nuclear magnetic resonance, the method using the above-mentioned device, comprising the following steps: The acquisition module is used to collect the superposition signal of the ECG signal and the nuclear magnetic noise under the condition of physical magnetic shielding, and the superposition signal is successively subjected to noise filtering and amplification to be used as the original ECG signal; The computing module is used to perform real-time frequency analysis on the original ECG signal, extract various ECG signal features in the frequency domain, reconstruct the mask vector after the real-time frequency analysis to filter the noise and reconstruct the time-domain R-wave signal, reconstruct the ECG signal based on the reconstructed time-domain R-wave signal and various ECG signal features, detect the R-wave trigger point based on the reconstructed ECG signal and generate a gating signal, and also perform missed triggering and false triggering detection on the R-wave trigger point in real time; The transmission module is used to output the reconstructed ECG signal, gating signal and various ECG signal features to the MRI system, and supports matching different gating trigger conditions based on the MRI scanning sequence.

[0017] To achieve the above-mentioned purpose of the invention, an embodiment further provides a computing device, including a memory and one or more processors, wherein the memory stores executable code, and when the one or more processors execute the executable code, they are used to implement the above-mentioned ECG gating signal processing method under nuclear magnetic resonance.

[0018] Compared with the prior art, the present invention has the following beneficial effects: The present invention reduces the influence of nuclear magnetic resonance from a physical level by physically magnetically shielding the acquisition module, calculation module, and transmission module integrated on the circuit board. On this basis, the original electrocardiogram signal is converted into the frequency domain, and the mask vector is reconstructed based on the electrocardiogram signal in the frequency domain, and the noise is filtered and the time domain R wave signal is reconstructed to reduce the influence of noise at the algorithm level. Then, the complete electrocardiogram signal is reconstructed based on the electrocardiogram signal characteristics and the reconstructed time domain R wave signal, and R wave positioning and detection are achieved based on this to trigger electrocardiogram gating, which can improve the accuracy of R wave positioning and reduce the influence of magnetic resonance. Moreover, since the entire process is based on the original electrocardiogram signal of the patient, accurate positioning of the R wave for individual differences can be achieved, thereby generating an accurate electrocardiogram gating signal.

[0019] The present invention can be used not only for prospective ECG gating, but also for retrospective ECG gating, reducing the time required for relevant practitioners to mark R waves, using a combined filtering method to remove interference signals in ECG signals and analyze ECG signal noise to reconstruct clean ECG signals, while also summarizing ECG-related features, continuously detecting false triggering and missed triggering, and improving the triggering accuracy of magnetic resonance imaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 is a schematic diagram of the structure of an electrocardiogram gating signal processing device for nuclear magnetic resonance provided by an embodiment; Figure 2 is a schematic diagram of physically magnetically shielding an integrated circuit board provided by an embodiment; Figure 3is a schematic diagram of an electrocardiogram signal with nuclear magnetic resonance scanning noise provided by an embodiment; Figure 4 The extracted and reconstructed time domain R wave signal provided by the embodiment; Figure 5 is the separated noise signal provided by the embodiment; Figure 6 is an example diagram of an original ECG signal and a reconstructed ECG signal, including a trigger signal, provided by an embodiment; Figure 7 is an example diagram of R wave error detection and correction provided by an embodiment; Figure 8 It is a flow chart of a method for processing ECG gating signals under nuclear magnetic resonance provided by an embodiment. DETAILED DESCRIPTION

[0022] To make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific implementation methods described herein are only used to explain the present invention and do not limit the scope of protection of the present invention.

[0023] The inventive concept of the present invention is to solve the problem in the related art that the ECG signal waveform is affected by magnetic resonance and produces a lot of noise that cannot accurately locate the R wave, and the problem that the R wave is difficult to locate due to the large difference in individual physiological conditions of patients. The embodiment of the present invention provides an ECG gating signal processing solution for nuclear magnetic resonance, which can accurately locate the R wave in the ECG signal under the nuclear magnetic resonance interference scenario, thereby improving the accuracy of generating ECG gating signals based on the R wave.

[0024] like Figure 1 As shown, an embodiment provides an ECG gating signal processing device for nuclear magnetic resonance, including an acquisition module, a calculation module, and a transmission module. The device uses a three-lead method to collect the subject's ECG signal. The acquisition module and the calculation module are placed on the side of the subject. The transmission module is connected to an optical fiber to extend out of the MRI detection room. Finally, the output port of the transmission module is connected to a computer connected to the MRI device to trigger the MRI gating sequence and transmit and record related data. When the device is turned on, the data of the preset time needs to be discarded due to the hardware power-on limitation, and then the ECG signal and the gating signal can be output.

[0025] In the embodiment, the acquisition module, the calculation module, and the transmission module are all integrated on an integrated circuit board and are physically magnetically shielded. Figure 2As shown, in a nuclear magnetic resonance environment, three layers of magnetic shielding are used to implement physical magnetic shielding for the integrated circuit board at the front end, including: covering the integrated circuit board with a non-magnetic shielding cover, and shielding the integrated circuit board covered with the non-magnetic shielding cover by wrapping and shielding it with an anti-magnetic shielding film, and then placing the integrated circuit board wrapped with the anti-magnetic shielding film in a shielding box, so that the superimposed signal of the electrocardiogram signal and the nuclear magnetic noise used by the integrated circuit board is protected by three layers of magnetic shielding, and at the same time, the subsequent data analysis and processing process and the transmission process are all protected by three layers of magnetic shielding, thereby reducing some interference from the nuclear magnetic noise at the physical level.

[0026] In the embodiment, the acquisition module is used to acquire the superposition signal of the ECG signal and the nuclear magnetic noise under the nuclear magnetic resonance environment according to the preset sampling rate under the physical magnetic shielding condition, and the superposition signal is noise-filtered and amplified in sequence as the original ECG signal. In this way, the preliminary noise reduction and enhancement function of the signal is completed, the magnetic shielding and enhancement function of the ECG signal of the hardware front end under the nuclear magnetic resonance environment is realized, and the signal-to-noise ratio is improved.

[0027] Specifically, the superimposed signal is subjected to noise filtering and amplification in sequence, including: the superimposed signal collected through the integrated circuit board is first subjected to front-end RF and anti-aliasing hardware low-pass filtering to filter out RF and static magnetic field coupling interference, and then the filtered signal is enhanced through the back-end modulation and amplification circuit to obtain the original electrocardiogram signal (i.e., the collected ECG signal) and output, such as Figure 3 Specifically, during filtering, the superimposed signals are sequentially combined and multiple filters are applied through filters with different weight parameters. The main purposes include but are not limited to: limiting the amplitude of the noise; filtering out some high-frequency noise without losing the ECG signal.

[0028] In an embodiment, the calculation module is used to perform real-time frequency analysis on the original ECG signal and extract various ECG signal features in the frequency domain. Specifically, the original ECG signal is subjected to real-time frequency analysis, that is, the original ECG signal can be converted to the frequency domain to obtain a frequency domain signal through Fourier transform, and the main frequency of the ECG signal and the noise frequency of the nuclear magnetic noise are identified in the frequency domain based on the frequency domain signal. The energy of the ECG QRS wave group is mainly concentrated in 0~40hz, and the peak energy is concentrated in 8~16hz, which is regarded as the main frequency of the ECG signal. Then, the filtered signal is obtained with the goal of retaining the main frequency of the ECG signal. Multiple numerical calculations are performed in the frequency domain based on the filtered signal and the original ECG signal to extract various ECG signal features, wherein various ECG signal features include but are not limited to ECG morphology features, heartbeat frequency features, signal amplitude features, ECG signal power spectrum density features, QRS wave peak energy features, etc.

[0029] The calculation module reconstructs the mask vector after real-time frequency analysis to filter the noise and reconstruct the time domain R wave signal, specifically including: after real-time frequency analysis, in the frequency domain, according to the main frequency of the identified ECG signal and the noise frequency of the nuclear magnetic noise, by comparing the clean ECG signal under normal ECG and the interference ECG signal under nuclear magnetic noise, the R wave frequency with the highest amplitude and the most significant ECG signal characteristics in the clean ECG signal is selected as the R wave frequency center, and an adaptive mask vector is constructed based on the R wave frequency center by similarity criteria and under constraints, wherein the constraints are to retain ECG-related bands as much as possible and to specifically eliminate noise bands. When constructing the mask vector, according to the similarity criterion, the ECG R wave band where the ECG frequency mainly exists based on the R wave frequency center is selected, and the mask vector is designed according to the clean ECG signal, and the ECG R wave band is assigned a value of 1, the noise band is assigned a value of 0, and the aliasing band transitioning between the ECG R wave band and the noise band is assigned a value in the interval of 0.1-0.9 to obtain the mask vector.

[0030] After obtaining the mask vector, a linear integration operation is performed on the frequency domain signal in the frequency domain according to the mask vector to mask the noise part to remove the noise frequency band, and then the signal is converted to the time domain through inverse Fourier transform to reconstruct the time domain R wave signal. Figure 4 To extract the reconstructed time domain R wave signal, Figure 5 is the noise signal separated based on the mask vector.

[0031] The calculation module also reconstructs the ECG signal based on the reconstructed time-domain R-wave signal and various ECG signal features. Specifically, the extracted time-domain R-wave signal is reversely calculated, and the complete ECG signal is reconstructed using various ECG signal features. Figure 6 The lower part, Figure 6 The upper part is the collected original ECG signal with noise.

[0032] The calculation module also detects R-wave trigger points based on the reconstructed ECG signal and generates a gating signal. Different from the common Pan-Tompkins algorithm, the R-wave detection algorithm adopted in the embodiment of the present invention uses a multi-threshold method combined with ECG features to generate a gating signal. Specifically, it automatically records R-wave signal-related features based on the reconstructed ECG signal, including but not limited to R-wave peak value, R-wave morphology, R-wave frequency, RR interval, R-wave slope, R-wave abundance, related spectrum, related power spectrum, etc. Then, the R-wave trigger point is detected based on the R-wave signal-related features. Specifically, a sliding window is used to perform a weighted average of the R-wave signal-related features in the window as the next R-wave trigger point threshold. The R-wave signal that exceeds the R-wave trigger point threshold is detected as the R-wave trigger point and a gating signal is generated. Figure 6 As shown, the gated signal is indicated by a red marker. Figure 6There is obvious magnetic field noise generated by MRI scanning, and the ECG is covered and almost invisible. During the entire acquisition process, the device of the present invention can continuously send gated signals and clean ECG signals. It should be noted that this embodiment adopts a sampling rate of 500 Hz, and all processing processes are completed and output within 2 ms.

[0033] While generating the gate signal, that is, during the real-time operation of the nuclear magnetic resonance device, the calculation module also performs missed triggering and false triggering detection on the R wave trigger point in real time. Specifically, during the detection process, the missed triggering or false triggering phenomenon of the R wave trigger point is judged in real time and dynamically. When missed triggering or false triggering occurs, the error correction program is started to retrospectively correct the reconstructed ECG signal data, and the R wave peak is matched through a higher R wave trigger point threshold in the stored data domain, the interference noise and the normal R wave peak are judged, and the R wave signal related features are updated with a certain weight. According to the summarized R wave signal related features, especially the interfered R wave signal related features under noise, the next correct R wave trigger point is found.

[0034] The calculation module provides the ability to correct missed triggers and false triggers by tracing back Figure 7 As shown, Figure 7 The upper middle picture shows the original ECG signal that was affected by the MRI scanning artifacts. The lower picture shows the filtered ECG signal. The output gated signal is marked with a red line. An incorrect judgment of the R wave occurred around 5 seconds. After the error was detected, it was corrected and accurate ECG judgment was restored within two heartbeat cycles.

[0035] In the embodiment, the transmission module is used to output the reconstructed ECG signal, the gating signal and various ECG signal features to the nuclear magnetic resonance system, and supports matching different gating trigger conditions based on the magnetic resonance scanning sequence. Specifically, during data transmission, a gating trigger method is used to output the reconstructed ECG signal and the gating signal according to a predetermined sampling rate to trigger the gating signal; the magnetic resonance scanning sequences supported at the same time include a custom prospective gating sequence and a retrospective gating sequence, and these two gating sequences match the custom gating trigger conditions to trigger the gating signal.

[0036] The device of the present invention can be used for prospective ECG gating, and can also replace relevant practitioners to mark the R wave of ECG signals. It is also suitable for retrospective ECG gating. During the test of this embodiment, quite a number of different gating sequences were used for testing, and it can be set to adapt to a variety of ECG gating sequences.

[0037] The device of the present invention outputs the processed clean ECG signal and the gating signal at the required sampling rate, and supports the matching of the gating trigger condition based on the magnetic resonance scanning sequence. The present invention solves the problem in the related art that the ECG signal is interfered by the nuclear magnetic resonance magnetic field noise, resulting in the inability to accurately locate the heart rhythm, thereby affecting the trigger accuracy in the magnetic resonance imaging. At the same time, accurate R wave marking can be performed in all collected ECG signals, which can be used not only for prospective ECG gating, but also for retrospective ECG gating, reducing the time required for relevant practitioners to mark the R wave, realizing the use of a combined filtering method to remove the interference signal in the ECG signal and analyze the ECG signal noise to reconstruct a clean ECG signal, and summarizing the ECG-related features, continuously detecting false triggering and missed triggering, and improving the trigger accuracy of nuclear magnetic resonance imaging.

[0038] like Figure 8 As shown, the embodiment further provides a method for processing ECG gating signals under nuclear magnetic resonance, the method using the above-mentioned ECG gating signal processing device, comprising the following steps: S1, using the acquisition module to collect the superposition signal of the ECG signal and the nuclear magnetic noise under the physical magnetic shielding condition, and performing noise filtering and amplification on the superposition signal in turn as the original ECG signal; S2, using the computing module to perform real-time frequency analysis on the original ECG signal, extract various ECG signal features in the frequency domain, reconstruct the mask vector after the real-time frequency analysis to filter the noise and reconstruct the time-domain R-wave signal, reconstruct the ECG signal based on the reconstructed time-domain R-wave signal and various ECG signal features, detect the R-wave trigger point based on the reconstructed ECG signal and generate a gating signal, and also perform missed triggering and false triggering detection on the R-wave trigger point in real time; S3 uses the transmission module to output the reconstructed ECG signal, gating signal and various ECG signal features to the MRI system, and supports matching different gating trigger conditions based on the MRI scanning sequence.

[0039] Based on the same inventive concept, an embodiment further provides a computing device, including a memory and one or more processors, wherein executable code is stored in the memory, and when the one or more processors execute the executable code, the method for processing ECG gating signals under nuclear magnetic resonance is implemented, specifically including the following steps: S1, using the acquisition module to collect the superposition signal of the ECG signal and the nuclear magnetic noise under the physical magnetic shielding condition, and performing noise filtering and amplification on the superposition signal in turn as the original ECG signal; S2, using the computing module to perform real-time frequency analysis on the original ECG signal, extract various ECG signal features in the frequency domain, reconstruct the mask vector after the real-time frequency analysis to filter the noise and reconstruct the time-domain R-wave signal, reconstruct the ECG signal based on the reconstructed time-domain R-wave signal and various ECG signal features, detect the R-wave trigger point based on the reconstructed ECG signal and generate a gating signal, and also perform missed triggering and false triggering detection on the R-wave trigger point in real time; S3 uses the transmission module to output the reconstructed ECG signal, gating signal and various ECG signal features to the MRI system, and supports matching different gating trigger conditions based on the MRI scanning sequence.

[0040] The computing device provided in the embodiment, in addition to the processor and memory, also includes hardware required for other services such as internal bus, network interface, memory, etc. at the hardware level. The memory is a non-volatile memory, and the processor reads the corresponding computer program from the non-volatile memory into the memory and then runs it to implement the ECG gating signal processing method for nuclear magnetic resonance described in S1-S3 above. Of course, in addition to the software implementation, the present invention does not exclude other implementation methods, such as logic devices or a combination of software and hardware, etc., that is to say, the execution subject of the following processing flow is not limited to each logic unit, but can also be hardware or logic devices.

[0041] The technical solution of the present invention adopts a denoising and restoring operation on the original ECG signal, and performs multiple numerical calculations to adaptively summarize the characteristics of various ECG signals, and adaptively summarizes multiple thresholds for the next R wave signal triggering according to the characteristics, and then detects the R wave trigger point to trigger ECG gating. The present invention does not require human-computer interaction to set the threshold, and eliminates the influence of inaccurate threshold triggering caused by artificial setting when signal fluctuations are generated.

[0042] The specific implementation methods described above provide a detailed description of the technical solutions and beneficial effects of the present invention. It should be understood that the above is only the most preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, supplements and equivalent substitutions made within the scope of the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A device for processing ECG gating signals under nuclear magnetic resonance, characterized in that: The acquisition module, calculation module, and transmission module are all integrated on the integrated circuit board and are physically magnetically shielded; The acquisition module is used to acquire the superposition signal of the ECG signal and the nuclear magnetic noise under the physical magnetic shielding condition, and perform noise filtering and amplification on the superposition signal in sequence as the original ECG signal; The calculation module is used to perform real-time frequency analysis on the original ECG signal, extract various ECG signal features in the frequency domain, reconstruct the mask vector after the real-time frequency analysis to filter the noise and reconstruct the time-domain R-wave signal, reconstruct the ECG signal based on the reconstructed time-domain R-wave signal and various ECG signal features, detect the R-wave trigger point based on the reconstructed ECG signal and generate a gating signal, and also perform missed triggering and false triggering detection on the R-wave trigger point in real time; The transmission module is used to output the reconstructed ECG signal, gating signal and various ECG signal features to the nuclear magnetic resonance system, and supports matching different gating trigger conditions based on the magnetic resonance scanning sequence.

2. The ECG gating signal processing device for nuclear magnetic resonance according to claim 1, characterized in that: The superimposed signal is noise filtered and amplified in sequence to obtain the original ECG signal, including: The superimposed signal collected by the integrated circuit board is first subjected to front-end RF and anti-aliasing hardware low-pass filtering to filter out RF and static magnetic field coupling interference, and then the filtered signal is enhanced by the back-end modulation and amplification circuit to obtain the original ECG signal and output it.

3. The ECG gating signal processing device for nuclear magnetic resonance according to claim 1, characterized in that: Perform real-time frequency analysis on the original ECG signal and extract various ECG signal features in the frequency domain, including: Perform real-time frequency analysis on the original ECG signal, convert the original ECG signal into the frequency domain to obtain a frequency domain signal, identify the main frequency of the ECG signal and the noise frequency of the nuclear magnetic noise based on the frequency domain signal in the frequency domain, and then retain the main frequency of the ECG signal to obtain a filtered signal; Multiple numerical calculations are performed on the original ECG signal and the filtered signal in the frequency domain to extract various ECG signal features, including ECG morphology features, heart rate features, signal amplitude features, ECG signal power spectrum density features, and QRS wave peak energy features.

4. The ECG gating signal processing device for nuclear magnetic resonance according to claim 3, characterized in that: Reconstruct the mask vector after real-time frequency analysis to filter the noise and reconstruct the time-domain R-wave signal, including: After real-time frequency analysis, in the frequency domain, according to the main frequency of the identified ECG signal and the noise frequency of the nuclear magnetic noise, by comparing the clean ECG signal under normal ECG and the interference ECG signal under nuclear magnetic noise, the R wave frequency with the highest amplitude and the most significant ECG signal characteristics in the clean ECG signal is screened out as the R wave frequency center. Based on the R wave frequency center, a mask vector is constructed through the similarity criterion and under the constraint condition, wherein the constraint condition is to retain the ECG-related bands as much as possible and specifically eliminate the noise bands; According to the mask vector, a linear integration operation is performed on the frequency domain signal in the frequency domain, and after the noise frequency band is removed, it is converted to the time domain and reconstructed into the time domain R wave signal.

5. The ECG gating signal processing device for nuclear magnetic resonance according to claim 3, characterized in that: Detect R wave trigger points based on reconstructed ECG signals and generate gating signals, including: Automatically record R wave signal related features based on the reconstructed ECG signal, wherein the R wave signal related features include R wave peak, R wave morphology, R wave frequency, RR interval, R wave slope, R wave abundance, related spectrum, and related power spectrum; Based on the relevant characteristics of the R wave signal, the R wave trigger point is detected and the gating signal is generated, including using a sliding window to perform weighted averaging on the relevant characteristics of the R wave signal in the window as the R wave trigger point threshold, and detecting the R wave signal that exceeds the R wave trigger point threshold as the R wave trigger point and generating a gating signal.

6. The ECG gating signal processing device for nuclear magnetic resonance according to claim 1, characterized in that: Real-time detection of missed triggering and false triggering of R wave trigger points, including: During the detection process, the missed triggering or false triggering of the R wave trigger point is judged in real time and dynamically. When a missed trigger or false trigger occurs, the error correction program is started to retrospectively correct the reconstructed ECG signal data. The R wave peak is matched with a higher R wave trigger point threshold in the stored data domain, the interference noise and the normal R wave peak are judged, and the R wave signal related features are updated with certain weights. According to the summarized R wave signal related features, especially the interfered R wave signal related features under noise, the next correct R wave trigger point is found.

7. The method for processing ECG gating signals under nuclear magnetic resonance according to claim 1, characterized in that: During data transmission, it is equipped with a gated trigger method to output the reconstructed ECG signal and gating signal according to the predetermined sampling rate to trigger the gating signal; the supported magnetic resonance scanning sequences include customized prospective gating sequences and retrospective gating sequences. These two gating sequences match the customized gating trigger conditions to trigger the gating signal.

8. The electrocardiogram gating signal processing device for nuclear magnetic resonance according to claim 1, characterized in that: In the nuclear magnetic resonance environment, three layers of magnetic shielding are used to achieve physical magnetic shielding for the front-end integrated circuit board, including: The integrated circuit board is covered with a non-magnetic shielding cover, and the integrated circuit board covered with the non-magnetic shielding cover is wrapped and shielded by an anti-magnetic shielding film, and then the integrated circuit board wrapped by the anti-magnetic shielding film is placed in a shielding box, so that the collected original electrocardiogram signal and the calculation and transmission processes of the electrocardiogram signal are protected by three layers of magnetic shielding.

9. A method for processing ECG gating signals under nuclear magnetic resonance, characterized in that: The method uses the device according to any one of claims 1 to 8, comprising the following steps: The acquisition module is used to collect the superposition signal of the ECG signal and the nuclear magnetic noise under the condition of physical magnetic shielding, and the superposition signal is successively subjected to noise filtering and amplification to be used as the original ECG signal; The computing module is used to perform real-time frequency analysis on the original ECG signal, extract various ECG signal features in the frequency domain, reconstruct the mask vector after the real-time frequency analysis to filter the noise and reconstruct the time-domain R-wave signal, reconstruct the ECG signal based on the reconstructed time-domain R-wave signal and various ECG signal features, detect the R-wave trigger point based on the reconstructed ECG signal and generate a gating signal, and also perform missed triggering and false triggering detection on the R-wave trigger point in real time; The transmission module is used to output the reconstructed ECG signal, gating signal and various ECG signal features to the MRI system, and supports matching different gating trigger conditions based on the MRI scanning sequence.

10. A computing device comprising a memory and one or more processors, wherein the memory stores executable code, characterized in that: When the one or more processors execute the executable code, they are used to implement the method for processing ECG gating signals under nuclear magnetic resonance as described in claim 9.

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