Magnetic resonance signal excitation and processing equipment

Abstract

The invention provides excitation and processing equipment for magnetic resonance signals, which can be applied to the technical field of magnetic resonance imaging. The device comprises a core processing module used for performing phase correction processing and modulation processing on an initial wave signal to generate an excitation pulse; the digital-to-analog conversion module is used for converting the excitation pulse into a radio frequency pulse; the preprocessing module is used for performing initial filtering processing on the received initial magnetic resonance signal to generate an amplified magnetic resonance signal; wherein the initial magnetic resonance signal is generated by exciting a radio frequency magnetic field by a radio frequency pulse; and the analog-to-digital conversion module is used for converting the amplified magnetic resonance signal into a digital magnetic resonance signal and transmitting the digital magnetic resonance signal to the core processing module, so that the core processing module is used for processing the digital magnetic resonance signal to generate a target magnetic resonance signal.

Description

Technical Field

[0001] The present disclosure relates to the technical field of magnetic resonance imaging, and more specifically, to a device for exciting and processing magnetic resonance signals. Background Art

[0002] Magnetic Resonance Imaging (MRI) is an important medical detection technology with advantages such as high resolution, no ionizing radiation, and multi-parameter imaging, so it is widely used in medical clinical examinations. At the same time, compared with computed tomography (CT) and ultrasound examinations, MRI does not require the use of X-rays and contrast agents, but instead generates images by changing the spin direction of water protons in the human body through an external magnetic field, so it is harmless to the human body and the imaging is more detailed.

[0003] In the process of realizing the concept of the present disclosure, the inventors discovered that in the related art, there are problems such as low integration, lack of flexibility and poor signal transmission quality of conventional magnetic resonance signal excitation or processing devices. Summary of the invention

[0004] In view of this, the present disclosure provides a device for exciting and processing magnetic resonance signals.

[0005] One aspect of the present disclosure provides a magnetic resonance signal excitation and processing device, comprising:

[0006] The core processing module is used to perform phase correction and modulation processing on the initial wave signal to generate an excitation pulse; the digital-to-analog conversion module is used to convert the excitation pulse into a radio frequency pulse; the preprocessing module is used to perform initial filtering processing on the received initial magnetic resonance signal to generate an amplified magnetic resonance signal; wherein the initial magnetic resonance signal is generated by exciting the radio frequency magnetic field with a radio frequency pulse; the analog-to-digital conversion module is used to convert the amplified magnetic resonance signal into a digital magnetic resonance signal and transmit it to the core processing module, so that the digital magnetic resonance signal can be processed by the core processing module to generate a target magnetic resonance signal.

[0007] According to an embodiment of the present disclosure, the initial wave signal includes a baseband wave and a carrier wave, and the initial wave signal is subjected to phase correction processing and modulation processing to generate an excitation pulse, including: reading a first accumulated phase timing data corresponding to the baseband wave and a second accumulated phase timing data corresponding to the carrier wave; processing the first accumulated phase timing data based on a first Taylor series equation corresponding to the first accumulated phase timing data to obtain a first correction signal corresponding to the baseband wave; processing the second accumulated phase timing data based on a second Taylor series equation corresponding to the second accumulated phase timing data to obtain a second correction signal corresponding to the carrier wave; and performing amplitude modulation processing on the first correction signal and the second correction signal to generate an excitation pulse.

[0008] According to an embodiment of the present disclosure, the first Taylor series equation includes multiple first Taylor expansion terms, and the first accumulated phase timing data is processed based on the first Taylor series equation corresponding to the first accumulated phase timing data to obtain a first correction signal corresponding to the baseband wave, including: obtaining a first phase error corresponding to each moment according to the first accumulated phase timing data; determining a first Taylor target term from multiple first Taylor expansion terms for the first phase error corresponding to each moment; and correcting the first phase error corresponding to each moment according to the first Taylor target term to obtain a first correction signal.

[0009] According to an embodiment of the present disclosure, the second Taylor series equation includes multiple second Taylor expansion terms, and the second accumulated phase timing data is processed based on the second Taylor series equation corresponding to the second accumulated phase timing data to obtain a second correction signal corresponding to the carrier, including: obtaining the second phase error corresponding to each moment according to the second accumulated phase timing data; determining a second Taylor target term from multiple second Taylor expansion terms for the second phase error corresponding to each moment; and correcting the second phase error corresponding to each moment according to the second Taylor target term to obtain a second correction signal.

[0010] According to an embodiment of the present disclosure, processing a digital magnetic resonance signal to generate a target magnetic resonance signal includes: performing down-conversion processing on the digital magnetic resonance signal to obtain a low-frequency magnetic resonance signal; and performing multiple filtering processing on the low-frequency resonance signal to obtain a target magnetic resonance signal.

[0011] According to an embodiment of the present disclosure, multiple filtering processes are performed on the low-frequency resonance signal to obtain a target magnetic resonance signal, including: performing extraction filtering processes on the low-frequency resonance signal to obtain a low-speed magnetic resonance signal; and performing Kalman filtering processes on the low-speed magnetic resonance signal to obtain a target magnetic resonance signal.

[0012] According to an embodiment of the present disclosure, the core processing module includes a Kalman filter unit; Kalman filter processing is performed on the low-speed magnetic resonance signal to obtain a target magnetic resonance signal, including: predicting the state parameters of the Kalman filter unit at the nth moment according to the state transition model of the Kalman filter unit at the n-1th moment and the received low-speed magnetic resonance signal, and obtaining the initial predicted state parameters corresponding to the nth moment; obtaining the prediction error covariance matrix corresponding to the nth moment according to the state transition model of the Kalman filter unit at the n-1th moment; obtaining the gain data corresponding to the nth moment according to the prediction error covariance matrix and the observation matrix corresponding to the nth moment; updating the initial predicted state parameters corresponding to the nth moment according to the gain data corresponding to the nth moment, and obtaining the target predicted state parameters corresponding to the nth moment; updating the prediction error covariance matrix corresponding to the nth moment according to the gain data corresponding to the nth moment, and obtaining the target error covariance matrix corresponding to the nth moment; obtaining the target magnetic resonance signal corresponding to the nth moment according to the target predicted state parameters corresponding to the nth moment and the target error covariance matrix corresponding to the nth moment.

[0013] According to an embodiment of the present disclosure, the above-mentioned device further includes: a parameter configuration submodule, which is used to adjust the preset parameters of the core processing module.

[0014] According to an embodiment of the present disclosure, the above-mentioned device further includes: an off-chip storage module, which is used to store candidate target magnetic resonance signals whose transmission rate is greater than a predetermined threshold in the target magnetic resonance signals.

[0015] According to an embodiment of the present disclosure, the above-mentioned device further includes: a network transmission module, which is used to transmit the target magnetic resonance signal to a computer to generate a magnetic resonance image according to the target magnetic resonance signal.

[0016] According to the embodiment of the present disclosure, the core processing module first generates a pulse for exciting the resonant magnetic field based on the initial wave signal, and the preprocessing module and the analog-to-digital conversion module receive the initial magnetic resonance signal excited by the radio frequency pulse and perform preliminary filtering processing, so that the core processing module further processes the received digital magnetic resonance signal after preliminary filtering to obtain a target magnetic resonance signal with a higher signal-to-noise ratio. Since multiple filtering processes are performed inside the device, the target magnetic resonance signal obtained has a higher signal-to-noise ratio and can adapt to different application scenarios. The excitation and processing operations of the magnetic resonance signal are integrated into the same programmable gate array (FPGA) chip, namely the core processing module, which has a high degree of integration, a simple device structure and a low signal delay. At the same time, the magnetic resonance image reconstructed according to the target magnetic resonance signal has a high quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0018] Figure 1 A schematic diagram of a conventional magnetic resonance signal excitation device according to an embodiment of the present disclosure is schematically shown.

[0019] Figure 2 The block diagram schematically shows a device for exciting and processing magnetic resonance signals according to an embodiment of the present disclosure.

[0020] Figure 3 The hardware architecture diagram of the magnetic resonance signal excitation and processing device according to the embodiment of the present disclosure is schematically shown.

[0021] Figure 4 The figure schematically shows a process of generating an excitation pulse according to an embodiment of the present disclosure.

[0022] Figure 5 The block diagram schematically shows the composition of the core processing module according to an embodiment of the present disclosure.

[0023] Figure 6 The figure schematically shows a physical schematic diagram of a magnetic resonance signal excitation and processing device according to an embodiment of the present disclosure.

[0024] Figure 7 The waveform diagram of the radio frequency pulse according to the embodiment of the present disclosure is schematically shown.

[0025] Figure 8 The figure schematically shows an amplitude diagram of a target magnetic resonance signal according to an embodiment of the present disclosure.

[0026] Fig. 9 A schematic diagram of a magnetic resonance image according to an embodiment of the present disclosure is schematically shown. DETAILED DESCRIPTION

[0027] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present disclosure. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0028] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0029] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0030] When using expressions such as "at least one of A, B, and C, etc.", they should generally be interpreted according to the meaning of the expression commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0031] In the embodiments of the present disclosure, the collection, updating, analysis, processing, use, transmission, provision, disclosure, storage, etc. of the data involved (for example, including but not limited to user personal information) are in compliance with the provisions of relevant laws and regulations, are used for legitimate purposes, and do not violate public order and good morals. In particular, necessary measures are taken for user personal information to prevent illegal access to user personal information data and maintain the security of user personal information, network security, and national security.

[0032] In the embodiments of the present disclosure, the user's authorization or consent is obtained before obtaining or collecting the user's personal information.

[0033] Because MRI has the characteristics of no radiation, high contrast and large amount of information, it is widely used in the imaging of soft tissues and blood vessels in the medical field, improving diagnostic efficiency and accuracy to a certain extent.

[0034] The processing of magnetic resonance imaging first requires corresponding magnetic field excitation equipment and magnetic resonance signal receiving equipment to obtain corresponding magnetic resonance signals. The magnetic field excitation or magnetic resonance signal receiving equipment in the related technology requires different chips to coordinate with each other to achieve, so the integration is low, the occupied area is large and the structure is complex. Secondly, the peripheral control chip is required to configure the parameters, which makes the equipment less flexible and has a certain transmission delay. At the same time, the relevant denoising algorithm is not used to improve the signal-to-noise ratio of the transmission signal, so the quality of the obtained magnetic resonance image needs to be improved.

[0035] In order to better understand the composition and architecture of traditional magnetic resonance signal excitation equipment, the following will be Figure 1A clearer illustration of the composition of the chip and other structures of the traditional magnetic resonance signal excitation device.

[0036] Figure 1 A schematic diagram of a conventional magnetic resonance signal excitation device according to an embodiment of the present disclosure is schematically shown.

[0037] like Figure 1 As shown, in the traditional magnetic resonance signal excitation device, the power supply circuit supplies power to the FPGA, DDS (Direct Digital Synthesis) and MCU (microprocessing unit) or DSP (digital signal processor) chips, and the clock reset circuit provides a reset clock signal to the FPGA, DDS chip and MCU or DSP. The DDS chip processes the generated initial pulse signal through the digital-to-analog conversion circuit and the amplification circuit, and outputs a radio frequency pulse signal for exciting the magnetic field to obtain a magnetic resonance signal. At the same time, the peripheral MCU or DSP configures the parameters of the FPGA.

[0038] In view of this, an embodiment of the present disclosure provides a magnetic resonance signal excitation and processing device, including:

[0039] The core processing module is used to perform phase correction and modulation processing on the initial wave signal to generate an excitation pulse; the digital-to-analog conversion module is used to convert the excitation pulse into a radio frequency pulse; the preprocessing module is used to perform initial filtering processing on the received initial magnetic resonance signal to generate an amplified magnetic resonance signal; wherein the initial magnetic resonance signal is generated by exciting the radio frequency magnetic field with a radio frequency pulse; the analog-to-digital conversion module is used to convert the amplified magnetic resonance signal into a digital magnetic resonance signal and transmit it to the core processing module, so that the digital magnetic resonance signal can be processed by the core processing module to generate a target magnetic resonance signal.

[0040] Figure 2 The block diagram schematically shows a device for exciting and processing magnetic resonance signals according to an embodiment of the present disclosure.

[0041] like Figure 2 As shown, the device 200 includes a core processing module 210 , a digital-to-analog conversion module 220 , a preprocessing module 230 and an analog-to-digital conversion module 240 .

[0042] According to an embodiment of the present disclosure, the core processing module 210 is used to perform phase correction processing and modulation processing on the initial wave signal to generate an excitation pulse.

[0043] According to the embodiments of the present disclosure, the initial wave signal can be generated based on the DDS technology. The DDS technology is a technology widely used in signal generation, and has the advantages of high spectral purity and flexible frequency switching. By inputting the frequency control word into the phase accumulator, the frequency control word is accumulated in each clock cycle, thereby generating a continuously increasing phase data in the phase register. Therefore, the frequency and phase of the initial wave signal can be adjusted by changing the frequency control word, thereby controlling the resolution of the initial wave signal. The output of the phase accumulator is the address of the lookup table, which stores the sampling values ​​of the initial wave signal (such as a sine wave) within a cycle, so the linear phase growth can be converted into waveform data corresponding to each sampling point through the lookup table.

[0044] According to an embodiment of the present disclosure, the initial wave signal generated by DDS will be affected by phase truncation error and quantization noise, so that the initial wave signal may contain some stray noise. Therefore, the noise signal can be shaped through correction processing and modulation processing to improve the signal-to-noise ratio of the initial wave signal.

[0045] According to an embodiment of the present disclosure, the digital-to-analog conversion module 220 is used to convert the excitation pulse into a radio frequency pulse.

[0046] According to an embodiment of the present disclosure, the excitation pulse outputs a radio frequency pulse through a digital-to-analog conversion module. The radio frequency pulse is a continuous wave and can generate a radio frequency magnetic field by exciting a radio frequency coil, causing the hydrogen nuclei of the human body to resonate, thereby obtaining an initial magnetic resonance signal.

[0047] According to an embodiment of the present disclosure, the preprocessing module 230 is used to perform initial filtering processing on the received initial magnetic resonance signal to generate an amplified magnetic resonance signal.

[0048] According to an embodiment of the present disclosure, the pre-processing module can receive the initial magnetic resonance signal and perform gain filtering processing, so that the obtained amplified resonance signal can be further filtered and processed by the core processing module.

[0049] According to an embodiment of the present disclosure, the analog-to-digital conversion module 240 is used to convert the amplified magnetic resonance signal into a digital magnetic resonance signal and transmit it to the core processing module, so that the core processing module can process the digital magnetic resonance signal to generate a target magnetic resonance signal.

[0050] According to an embodiment of the present disclosure, the analog-to-digital conversion module may be an eight-channel analog-to-digital converter.

[0051] According to the embodiments of the present disclosure, FPGA is a semi-customized circuit in a special application integrated circuit, which can be customized and designed to process data in real time, so it has powerful parallel computing capabilities and low latency performance, can realize signal processing and generation functions, and is suitable for the field of magnetic resonance. Compared with traditional devices, the pulse signal generation of the magnetic field excitation and the magnetic resonance signal processing in the embodiments of the present disclosure are both implemented inside the FPGA, so the integration is high and the cost is effectively reduced.

[0052] According to the embodiment of the present disclosure, the core processing module first generates a pulse for exciting a resonant magnetic field based on an initial wave signal, and the preprocessing module and the analog-to-digital conversion module receive the initial magnetic resonance signal excited by the radio frequency pulse and perform preliminary filtering processing, so that the core processing module further processes the received digital magnetic resonance signal after preliminary filtering to obtain a target magnetic resonance signal with a higher signal-to-noise ratio. Since multiple filtering processes are performed inside the device, the target magnetic resonance signal obtained has a higher signal-to-noise ratio and can adapt to different application scenarios. And since the excitation and processing modules of the magnetic resonance signal are integrated on the same field programmable gate array (FPGA) chip, it has a high degree of integration, and the excitation and processing of the magnetic resonance signal are both implemented based on FPGA, which makes the device structure simple and the signal delay low. At the same time, the magnetic resonance image reconstructed according to the target magnetic resonance signal has a high quality.

[0053] According to an embodiment of the present disclosure, the above-mentioned device further includes: an off-chip storage module, which is used to store candidate target magnetic resonance signals whose transmission rate is greater than a predetermined threshold in the target magnetic resonance signals.

[0054] According to an embodiment of the present disclosure, the off-chip storage module may be DDR3 (Double Data Rate 3, the third generation of double data rate synchronous dynamic random access memory). The candidate target magnetic resonance signal with a transmission rate greater than a predetermined threshold value also needs to be processed at a reduced rate, otherwise it is easy to cause data loss during the transmission process, thereby affecting the transmission quality.

[0055] According to an embodiment of the present disclosure, the above-mentioned device further includes: a network transmission module, which is used to transmit the target magnetic resonance signal to a computer to generate a magnetic resonance image according to the target magnetic resonance signal.

[0056] According to an embodiment of the present disclosure, the network transmission module may be an Ethernet interface chip, the target magnetic resonance signal is transmitted to the computer terminal through the network transmission module, and image reconstruction is performed on the target magnetic resonance signal.

[0057] In order to better understand the embodiments of the present disclosure, Figure 3 The hardware architecture of the above-mentioned magnetic resonance signal excitation and processing equipment is described in detail.

[0058] Figure 3 The hardware architecture diagram of the magnetic resonance signal excitation and processing device according to the embodiment of the present disclosure is schematically shown.

[0059] like Figure 3 As shown, the embodiment 300 includes a core processing module, an analog-to-digital conversion module, a digital-to-analog conversion module, a coil and magnet module, a preprocessing module, an off-chip storage module, and a network transmission module.

[0060] According to an embodiment of the present disclosure, the core processing module sends the excitation pulse to the digital-to-analog conversion module to obtain a radio frequency pulse. The radio frequency pulse excites the radio frequency magnetic field through the coil and magnet module to generate an initial magnetic resonance signal. After receiving the initial magnetic resonance signal, the preprocessing module performs initial filtering processing.

[0061] Among them, the preprocessing module includes VGA (Variable Gain Amplifier), which is an amplifier that can dynamically adjust its gain according to an external control signal to ensure the stability of the output signal. It is widely used in applications that require precise control of the signal amplification factor; the preprocessing module includes BPF (Band Pass Filter), which is a filter that only allows signals within a certain frequency range to pass through and can suppress signals below and above the frequency band; the preprocessing module also includes AMP (Amplifier), which is used to increase the amplitude of the signal while maintaining the frequency and phase characteristics of the signal; the preprocessing module also includes LPF (Low Pass Filter), which is used to remove high-frequency noise or limit the bandwidth of the signal to make the signal purer. The types of filters in the preprocessing module in the figure are only schematic, and the specific types and compositions can be designed according to actual needs.

[0062] According to an embodiment of the present disclosure, the digital-to-analog conversion module can use a chip with model number AD9767BRUZ; the analog-to-digital conversion module can use a chip with model number AD9257BCPZ-65; the core processing module can use a chip with model number FPGA Artix-7 XC7A200T-2FBG484I; and the network transmission module can use a chip with model number KSZ9031RNX.

[0063] According to an embodiment of the present disclosure, the initial magnetic resonance signal is processed by VGA, BPF, AMP and LPF in sequence to obtain an amplified magnetic resonance signal, and the analog-to-digital conversion module performs analog-to-digital conversion on the amplified magnetic resonance signal to obtain a digital magnetic resonance signal that can be further processed by the core processing module.

[0064] According to an embodiment of the present disclosure, the initial wave signal includes a baseband wave and a carrier wave, and the initial wave signal is subjected to phase correction processing and modulation processing to generate an excitation pulse, including: reading a first accumulated phase timing data corresponding to the baseband wave and a second accumulated phase timing data corresponding to the carrier wave; processing the first accumulated phase timing data based on a first Taylor series equation corresponding to the first accumulated phase timing data to obtain a first correction signal corresponding to the baseband wave; processing the second accumulated phase timing data based on a second Taylor series equation corresponding to the second accumulated phase timing data to obtain a second correction signal corresponding to the carrier wave; and performing amplitude modulation processing on the first correction signal and the second correction signal to generate an excitation pulse.

[0065] According to an embodiment of the present disclosure, the first accumulated phase timing data represents the phase accumulated data of the baseband wave at each corresponding moment, and the second accumulated phase timing data represents the phase accumulated data of the carrier at each corresponding moment.

[0066] According to an embodiment of the present disclosure, the corresponding relationship between the first accumulated phase timing data and the time can be expressed as the following formula (1).

[0067] (1)

[0068] in, represents the first accumulated phase timing data corresponding to the nth moment, represents the phase increment data, Indicates the clock frequency, Indicates the frequency of the output wave signal corresponding to the baseband wave.

[0069] According to the embodiment of the present disclosure, the corresponding relationship between the second accumulated phase timing data and the time instant is similar to the above formula (1), which will not be elaborated here. The following processing of the initial wave signal is explained by taking the baseband wave as an example.

[0070] According to an embodiment of the present disclosure, due to the limited precision of the phase accumulator in the DDS, the first accumulated phase timing data and the second accumulated phase timing data may be truncated in actual calculation, resulting in a phase error, that is, a spurious noise signal appears in the frequency domain.

[0071] According to an embodiment of the present disclosure, the phase error can be expressed as the following formula (2).

[0072] (2)

[0073] in, is the phase error of the baseband wave, is the actual first accumulated phase timing data, is the first accumulated phase timing data obtained by calculation.

[0074] According to the embodiments of the present disclosure, a Taylor series noise shaping algorithm can be used to perform approximate phase correction. The phase error is corrected according to the Taylor series equation to obtain a corrected first correction signal and a second correction signal, which effectively improves the spectral purity of the initial wave signal, offsets the error caused by phase truncation, and reduces stray noise.

[0075] According to an embodiment of the present disclosure, amplitude modulation processing is performed on the first correction signal and the second correction signal, including performing amplitude modulation on the first correction signal and the second correction signal through a multiplier.

[0076] In order to better understand the process of DDS generating baseband waves and carrier waves, the following diagram will illustrate the process of DDS generating baseband waves and carrier waves.

[0077] In order to better understand the process of DDS generating baseband wave and carrier wave, the following will be Figure 4 The process of DDS generating baseband wave and carrier wave and modulating to obtain excitation pulse is illustrated.

[0078] Figure 4 The figure schematically shows a process of generating an excitation pulse according to an embodiment of the present disclosure.

[0079] like Figure 4 As shown in the figure, DDS technology stores the frequency in the frequency register according to the input frequency tuning word, and accumulates the phase in the phase accumulator. The output of the phase accumulator is the address of the lookup table. In the lookup table, the output value of the required waveform is obtained according to the corresponding phase growth, and the carrier and baseband waves are obtained. The phase truncation of the carrier and baseband waves is corrected respectively, and then multiplied and modulated to obtain the excitation pulse. The generation process of the excitation pulse is based on FPGA, so the obtained signal excitation pulse is real-time.

[0080] According to an embodiment of the present disclosure, the first Taylor series equation includes multiple first Taylor expansion terms, and the first accumulated phase timing data is processed based on the first Taylor series equation corresponding to the first accumulated phase timing data to obtain a first correction signal corresponding to the baseband wave, including: obtaining a first phase error corresponding to each moment according to the first accumulated phase timing data; determining a first Taylor target term from multiple first Taylor expansion terms for the first phase error corresponding to each moment; and correcting the first phase error corresponding to each moment according to the first Taylor target term to obtain a first correction signal.

[0081] According to an embodiment of the present disclosure, the first Taylor series equation can be expressed as the following formula (3).

[0082] (3)

[0083] According to an embodiment of the present disclosure, the phase error at a certain moment can be approximately expressed as a nonlinear function , is the base point of the first Taylor series expansion, Etc. respectively indicate exist The first derivative, second derivative, etc.

[0084] According to an embodiment of the present disclosure, the first Taylor objective term is a more appropriate expansion term in the above formula (3), which can be used to correct the phase error at the corresponding moment.

[0085] According to an embodiment of the present disclosure, using the first Taylor objective term to correct the first phase error corresponding to each moment can be expressed as the following formula (4).

[0086] (4)

[0087] in, represents the first correction signal corresponding to the nth moment, is the first Taylor objective term. The phase correction process is to add the corresponding first Taylor objective term to In the process, the phase response is adjusted to offset the phase error.

[0088] According to an embodiment of the present disclosure, the process of modulating the first correction signal can be expressed as the following formula (5).

[0089] (5)

[0090] in, is the modulated first correction signal, and A is the amplitude of the first correction signal.

[0091] According to the embodiments of the present disclosure, according to the above formula (4), by selecting appropriate Taylor expansion terms, the influence of the phase error on the spectrum of the DDS output wave signal can be described more accurately.

[0092] According to an embodiment of the present disclosure, the second Taylor series equation includes multiple second Taylor expansion terms, and the second accumulated phase timing data is processed based on the second Taylor series equation corresponding to the second accumulated phase timing data to obtain a second correction signal corresponding to the carrier, including: obtaining the second phase error corresponding to each moment according to the second accumulated phase timing data; determining a second Taylor target term from multiple second Taylor expansion terms for the second phase error corresponding to each moment; and correcting the second phase error corresponding to each moment according to the second Taylor target term to obtain a second correction signal.

[0093] According to an embodiment of the present disclosure, the correction of the second phase error is similar to the above formulas (3) and (4), which will not be described in detail here.

[0094] According to the embodiment of the present disclosure, the first Taylor expansion term and the second Taylor expansion term are introduced into the signal processing path inside the FPGA where the core processing module is located, and the accumulated phase timing data of the phase accumulator is efficiently corrected in real time to ensure the synchronization of the signal. At the same time, the number of terms of the first Taylor expansion term and the second Taylor expansion term is optimized, and only the best combination between resource occupancy and signal shaping effect is selected, thereby achieving a balance between resource consumption and signal quality. Phase correction improves the spectral purity of the baseband wave and the carrier signal by adding appropriate Taylor target terms to the accumulated phase timing data, reduces the amplitude of the stray noise and thus improves the signal-to-noise ratio of the excitation pulse without significantly increasing the hardware complexity, ensures that the subsequent processing of the magnetic resonance signal can work in a high noise suppression environment, and improves the robustness of the device.

[0095] According to an embodiment of the present disclosure, processing a digital magnetic resonance signal to generate a target magnetic resonance signal includes: performing down-conversion processing on the digital magnetic resonance signal to obtain a low-frequency magnetic resonance signal; and performing multiple filtering processing on the low-frequency resonance signal to obtain a target magnetic resonance signal.

[0096] According to the embodiments of the present disclosure, down-conversion processing is a process of converting these high-frequency digital magnetic resonance signals into lower frequencies, which is beneficial for making subsequent processing of low-frequency magnetic resonance signals easier and more efficient.

[0097] According to an embodiment of the present disclosure, the core processing module includes a variety of different filters that can perform multiple filtering on the low-frequency magnetic resonance signal, such as CIC filter (integral-comb cascade filter), CIC compensation filter (integral-comb cascade compensation filter), Kalman filter and half-band filter.

[0098] According to an embodiment of the present disclosure, multiple filtering processes are performed on the low-frequency resonance signal to obtain a target magnetic resonance signal, including: performing extraction filtering processes on the low-frequency resonance signal to obtain a low-speed magnetic resonance signal; and performing Kalman filtering processes on the low-speed magnetic resonance signal to obtain a target magnetic resonance signal.

[0099] According to an embodiment of the present disclosure, extraction and filtering of low-frequency resonance signals can be implemented using a CIC filter (integral-comb cascade filter) and a CIC compensation filter (integral-comb cascade compensation filter) to reduce the rate of the low-frequency resonance signal. Signals with a rate lower than a predetermined threshold are low-speed magnetic resonance signals, and signals with a rate higher than the predetermined threshold are temporarily stored in an off-chip storage module.

[0100] According to an embodiment of the present disclosure, before performing Kalman filtering processing on the low-speed magnetic resonance signal using the Kalman filter, it is also necessary to perform filtering using a half-band filter.

[0101] According to the embodiments of the present disclosure, Kalman filtering is a recursive minimum mean square error estimation algorithm, which is mainly used for dynamic system state estimation and noise suppression. Due to its excellent performance in processing dynamic systems with Gaussian white noise, it is widely used in target tracking, navigation systems, signal processing and other fields. Kalman filtering is based on the state space model of the linear system, combines the current observation value with the prior estimate, and gradually updates the optimal estimate of the system state, thereby realizing real-time denoising and parameter estimation of the signal.

[0102] According to an embodiment of the present disclosure, a core processing module includes: a parameter configuration submodule, which is used to adjust preset parameters of the core processing module.

[0103] According to an embodiment of the present disclosure, the parameter configuration submodule can flexibly configure the functional parameters of various parts in the device, such as: preset parameters of the Kalman filter unit, preset parameters of the down-conversion unit, preset parameters of the digital-to-analog conversion module, etc.

[0104] According to the embodiments of the present disclosure, since the parameters of the device can be modified without the need for an external DSP or MCU, the flexibility of the device is effectively improved, large transmission delays are avoided, and the parameter configuration function is integrated into the same FPGA chip, which reduces the cost of the device and solves the technical problems of low integration and large area occupied by traditional devices.

[0105] Figure 5 The block diagram schematically shows the composition of the core processing module according to an embodiment of the present disclosure.

[0106] like Figure 5 As shown, the core processing module 210 includes an analog-to-digital conversion module configuration submodule, an excitation pulse generation submodule, a processing submodule, a parameter configuration submodule, a data interaction submodule and a communication submodule.

[0107] According to an embodiment of the present disclosure, the excitation pulse generation submodule is connected to the digital-to-analog conversion module, and the excitation pulse generation submodule includes a DDS unit, a phase error correction unit and a multiplication modulation unit; the analog-to-digital conversion module configuration submodule includes a data configuration unit and a data acquisition unit; the digital-to-analog conversion module configuration submodule is connected to the processing submodule, and the processing submodule includes a down-conversion unit, a CIC filter unit, a CIC compensation filter unit, a half-band filter unit and a Kalman filter unit; the data interaction submodule performs data interaction with the off-chip storage module; and the communication submodule performs data transmission with the network transmission module.

[0108] According to an embodiment of the present disclosure, the core processing module includes a Kalman filter unit; Kalman filter processing is performed on the low-speed magnetic resonance signal to obtain a target magnetic resonance signal, including: predicting the state parameters of the Kalman filter unit at the nth moment according to the state transition model of the Kalman filter unit at the n-1th moment and the received low-speed magnetic resonance signal, and obtaining the initial predicted state parameters corresponding to the nth moment; obtaining the prediction error covariance matrix corresponding to the nth moment according to the state transition model of the Kalman filter unit at the n-1th moment; obtaining the gain data corresponding to the nth moment according to the prediction error covariance matrix and the observation matrix corresponding to the nth moment; updating the initial predicted state parameters corresponding to the nth moment according to the gain data corresponding to the nth moment, and obtaining the target predicted state parameters corresponding to the nth moment; updating the prediction error covariance matrix corresponding to the nth moment according to the gain data corresponding to the nth moment, and obtaining the target error covariance matrix corresponding to the nth moment; obtaining the target magnetic resonance signal corresponding to the nth moment according to the target predicted state parameters corresponding to the nth moment and the target error covariance matrix corresponding to the nth moment.

[0109] According to an embodiment of the present disclosure, based on the state transition model of the Kalman filter unit at the n-1th moment and the received low-speed magnetic resonance signal, the state parameters of the Kalman filter unit at the nth moment are predicted, and the initial predicted state parameters corresponding to the nth moment are obtained, that is, the state at the current moment can be predicted based on the state at the previous moment.

[0110] According to an embodiment of the present disclosure, the state transition model corresponding to the Kalman filter unit at the nth time can be expressed as the following formula (6).

[0111] (6)

[0112] Among them, X n represents the state parameter at the nth moment, X n-1 represents the state parameter at the n-1th moment, A represents the state transfer matrix, B represents the control input matrix, represents the control input, A noise signal representing the transfer process.

[0113] According to the embodiment of the present disclosure, using the above formula (6), the initial predicted state parameter at the nth moment can be obtained according to the following formula (7).

[0114] (7)

[0115] in, represents the initial prediction state parameter at the nth moment, Represents the predicted state parameters at the n-1th moment.

[0116] According to an embodiment of the present disclosure, the prediction error covariance matrix P corresponding to the nth moment can be obtained according to the following formula (8): n - .

[0117] (8)

[0118] Among them, P n-1 represents the target error covariance matrix corresponding to the n-1th moment. The error covariance matrix can describe the uncertainty of state prediction. Q is related to The corresponding noise covariance matrix.

[0119] According to an embodiment of the present disclosure, the gain data is a Kalman gain, which can fuse weighted prediction values ​​and observation values ​​and adjust weights according to statistical characteristics, thereby achieving a balance between the predicted magnetic resonance signal and the noise signal.

[0120] According to an embodiment of the present disclosure, the gain data corresponding to the nth moment can be obtained according to the following formula (9): .

[0121] (9)

[0122] Among them, H is the observation matrix and R is the observation noise covariance matrix.

[0123] According to the embodiment of the present disclosure, the above formula (7) can be updated according to the following formula (10) to obtain the target prediction state parameter x corresponding to the nth moment: n .

[0124] (10)

[0125] Among them, z n is the observed value.

[0126] According to the embodiment of the present disclosure, the above formula (8) can be updated according to the following formula (11) to obtain the target prediction state parameter P corresponding to the nth moment: n .

[0127] (11)

[0128] Where I is the identity matrix.

[0129] According to the embodiments of the present disclosure, the Kalman filter can dynamically adjust the degree of dependence on the observed data according to the statistical characteristics of the noise signal. For example, when the observed data has large noise, the Kalman filter will tend to trust the prediction results, reduce the impact of the noise signal on the predicted signal, and thus suppress the noise. The Kalman filter unit calculates the optimal estimate of the state at each step, and through the Kalman gain, the signal-to-noise ratio can be maximized even in a high noise environment.

[0130] According to the embodiments of the present disclosure, the recursive structure of the Kalman filter unit is used to update the system state in real time, thereby gradually reducing the prediction error. As time goes by, the Kalman filter unit will track the magnetic resonance signal more and more accurately, so that the noise is gradually suppressed, thereby effectively improving the signal-to-noise ratio, thereby obtaining a target magnetic resonance signal with higher quality.

[0131] Figure 6 The figure schematically shows a physical schematic diagram of a magnetic resonance signal excitation and processing device according to an embodiment of the present disclosure.

[0132] like Figure 6 As shown, embodiment 600 shows corresponding physical diagrams of a radio frequency pulse transmission module, a preprocessing module, a core processing module, an off-chip storage module, and a network transmission module.

[0133] Figure 7 The waveform diagram of the radio frequency pulse according to the embodiment of the present disclosure is schematically shown.

[0134] like Figure 7 As shown in the figure, the peak value of the radio frequency pulse displayed on the oscilloscope is 207Mv (millivolts). The signal quality obtained after the radio frequency pulse is corrected by the Taylor series algorithm is high, which helps to improve the clarity and accuracy of MRI imaging.

[0135] Figure 8 The figure schematically shows an amplitude diagram of a target magnetic resonance signal according to an embodiment of the present disclosure.

[0136] like Figure 8 As shown, the waveform of the amplitude of the target magnetic resonance signal changing with time is relatively smooth without sawtooth jitter, which shows that the quality of the target magnetic resonance signal is high and has a high signal-to-noise ratio.

[0137] Fig. 9 A schematic diagram of a magnetic resonance image according to an embodiment of the present disclosure is schematically shown.

[0138] like Fig. 9 As shown, the reconstructed magnetic resonance image is clearer and of higher quality.

[0139] The flowcharts and block diagrams in the accompanying drawings illustrate the possible implementation architecture, functions and operations of the devices according to various embodiments of the present disclosure. In this regard, each box in the flowchart or block diagram may represent a module, a program segment, or a part of a code, and the above-mentioned module, program segment, or a part of the code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box may also occur in an order different from that marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram or flowchart, and the combination of boxes in the block diagram or flowchart, can be implemented with a dedicated hardware-based system that performs a specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions. It can be understood by those skilled in the art that the features recorded in the various embodiments of the present disclosure can be combined and / or combined in various ways, even if such a combination or combination is not explicitly recorded in the present disclosure. In particular, without departing from the spirit and teachings of the present disclosure, the features recorded in the various embodiments of the present disclosure can be combined and / or combined in various ways. All such combinations and / or combinations fall within the scope of the present disclosure.

[0140] The embodiments of the present disclosure are described above. However, these embodiments are only for illustrative purposes and are not intended to limit the scope of the present disclosure. Although the embodiments are described above, this does not mean that the measures in the various embodiments cannot be used in combination to advantage. Without departing from the scope of the present disclosure, those skilled in the art may make a variety of substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims

1. A magnetic resonance signal excitation and processing device, comprising: The core processing module is used to perform phase correction and modulation processing on the initial wave signal to generate an excitation pulse; A digital-to-analog conversion module, used for converting the excitation pulse into a radio frequency pulse; A preprocessing module, configured to perform initial filtering processing on the received initial magnetic resonance signal to generate an amplified magnetic resonance signal; wherein the initial magnetic resonance signal is generated by exciting a radio frequency magnetic field by the radio frequency pulse; The analog-to-digital conversion module is used to convert the amplified magnetic resonance signal into a digital magnetic resonance signal and transmit it to the core processing module, so that the digital magnetic resonance signal can be processed by the core processing module to generate a target magnetic resonance signal.

2. The device according to claim 1, wherein: The initial wave signal includes a baseband wave and a carrier wave, and the phase correction processing and modulation processing are performed on the initial wave signal to generate an excitation pulse, including: Reading first accumulated phase timing data corresponding to the baseband wave and second accumulated phase timing data corresponding to the carrier wave; Processing the first accumulated phase time series data based on a first Taylor series equation corresponding to the first accumulated phase time series data to obtain a first correction signal corresponding to the baseband wave; Processing the second accumulated phase timing data based on a second Taylor series equation corresponding to the second accumulated phase timing data to obtain a second correction signal corresponding to the carrier; The first correction signal and the second correction signal are amplitude modulated to generate the excitation pulse.

3. The device according to claim 2, wherein: The first Taylor series equation includes a plurality of first Taylor expansion terms, and the first accumulated phase time series data is processed based on the first Taylor series equation corresponding to the first accumulated phase time series data to obtain a first correction signal corresponding to the baseband wave, including: Obtaining a first phase error corresponding to each moment according to the first accumulated phase time series data; For the first phase error corresponding to each moment, determining a first Taylor target term from the plurality of first Taylor expansion terms; According to the first Taylor target term, the first phase error corresponding to each moment is corrected to obtain the first correction signal.

4. The device according to claim 2, wherein: The second Taylor series equation includes a plurality of second Taylor expansion terms, and the second accumulated phase timing data is processed based on the second Taylor series equation corresponding to the second accumulated phase timing data to obtain a second correction signal corresponding to the carrier, including: Obtaining a second phase error corresponding to each moment according to the second accumulated phase timing data; For the second phase error corresponding to each moment, determining a second Taylor target term from the plurality of second Taylor expansion terms; According to the second Taylor objective term, the second phase error corresponding to each moment is corrected to obtain the second correction signal.

5. The device according to claim 1, wherein: The step of processing the digital magnetic resonance signal to generate a target magnetic resonance signal comprises: Performing down-conversion processing on the digital magnetic resonance signal to obtain a low-frequency magnetic resonance signal; The low-frequency resonance signal is subjected to multiple filtering processes to obtain the target magnetic resonance signal.

6. The device according to claim 5, wherein: The step of performing multiple filtering processes on the low-frequency resonance signal to obtain the target magnetic resonance signal includes: Performing extraction and filtering processing on the low-frequency resonance signal to obtain a low-speed magnetic resonance signal; Kalman filtering is performed on the low-speed magnetic resonance signal to obtain the target magnetic resonance signal.

7. The device according to claim 6, wherein: The core processing module includes a Kalman filter unit; the Kalman filter processing is performed on the low-speed magnetic resonance signal to obtain the target magnetic resonance signal, including: Predicting the state parameters of the Kalman filter unit at the nth moment according to the state transition model of the Kalman filter unit at the n-1th moment and the received low-speed magnetic resonance signal, to obtain the initial predicted state parameters corresponding to the nth moment; According to the state transition model of the Kalman filter unit at the n-1th moment, a prediction error covariance matrix corresponding to the nth moment is obtained; Obtaining gain data corresponding to the nth moment according to the prediction error covariance matrix and the observation matrix corresponding to the nth moment; According to the gain data corresponding to the nth moment, the initial prediction state parameter corresponding to the nth moment is updated to obtain the target prediction state parameter corresponding to the nth moment; According to the gain data corresponding to the nth moment, the prediction error covariance matrix corresponding to the nth moment is updated to obtain the target error covariance matrix corresponding to the nth moment; The target magnetic resonance signal corresponding to the nth moment is obtained according to the target predicted state parameter corresponding to the nth moment and the target error covariance matrix corresponding to the nth moment.

8. The device according to claim 1, wherein: The core processing module further includes: The parameter configuration submodule is used to adjust the preset parameters of the core processing module.

9. The device according to claim 1, wherein: Also includes: The off-chip storage module is used to store candidate target magnetic resonance signals whose transmission rate is greater than a predetermined threshold among the target magnetic resonance signals.

10. The device according to claim 1, wherein: Also includes: A network transmission module is used to transmit the target magnetic resonance signal to a computer to generate a magnetic resonance image according to the target magnetic resonance signal.

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