Magnetic resonance imaging method and system, intelligent terminal and storage medium
By acquiring the first echo signal without phase-coded gradient as reference data, and combining phase matrix processing and low-pass filtering techniques, the problem of artifacts in magnetic resonance imaging was solved, thereby improving image clarity and diagnostic accuracy.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- XINGAOYI MEDICAL EQUIPMENT CO LTD
- Filing Date
- 2026-01-26
- Publication Date
- 2026-05-12
AI Technical Summary
In magnetic resonance imaging, the periodic changes in the spatial position of the magnet center in a strong magnetic field cause periodic amplitude and phase changes in the acquired data, resulting in artifacts in the generated magnetic resonance images, which affect image clarity and diagnostic accuracy.
The first echo signal without phase-coded gradient is acquired as reference data. By performing phase compensation on the imaging data, the stable phase error caused by the system hardware is eliminated. Phase matrix processing and low-pass filtering techniques are used to accurately correct artifacts.
It significantly improves the clarity and diagnostic accuracy of magnetic resonance images, eliminates artifacts caused by systematic errors, and improves image uniformity and multi-channel imaging quality.
Smart Images
Figure CN122017705A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of magnetic resonance imaging technology, and in particular to a magnetic resonance imaging method, system, smart terminal and storage medium. Background Technology
[0002] In the field of medical imaging, magnetic resonance imaging (MRI) technology has continuously developed and made significant progress. As an important medical examination tool, MRI provides doctors with detailed information about the internal structure of the human body, aiding in disease diagnosis and treatment. With advancements in technology, MRI technology has improved in resolution and imaging speed, making its clinical application increasingly valuable and helping doctors to more accurately assess conditions and develop more appropriate treatment plans.
[0003] The relevant technology involves placing the human body in a strong magnetic field and using radio frequency pulses to excite the hydrogen nuclei (such as hydrogen in water molecules) in the body, causing them to resonate and emit signals. Subsequently, the system uses spatial coding technology (gradient magnetic field) to locate the signals at different positions, and these signals are collected by receiving coils. Finally, the computer processes the collected signals and reconstructs the images to generate magnetic resonance images that reflect the internal tissue structure and function of the human body.
[0004] Regarding the aforementioned technologies, the spatial position of the magnet center in a strong magnetic field will change periodically, causing periodic amplitude and phase changes in the acquired data, resulting in artifacts in the generated magnetic resonance images. Summary of the Invention
[0005] To eliminate artifacts in magnetic resonance imaging, this application provides a magnetic resonance imaging method, system, smart terminal, and storage medium.
[0006] In a first aspect, this application provides a magnetic resonance imaging method, which adopts the following technical solution: A magnetic resonance imaging method, comprising: After the radio frequency pulse is applied, the first echo signal within the first time period is acquired to obtain reference data. The first echo signal uses a phase-free coded gradient. The second echo signal within the second time period is acquired to obtain imaging data. The second echo signal is phase-coded gradient. Based on the reference data, the phase compensation amount is obtained; The imaging data is phase-compensated according to the phase compensation amount to obtain compensated imaging data. The compensated imaging data is used to reconstruct the image to obtain a magnetic resonance image.
[0007] By employing the above technical solution and using the first echo signal without phase-coded gradient as reference data, stable phase errors caused by system hardware can be directly and specifically captured and separated. Subsequently, the phase compensation amount obtained from this reference data is used to correct the imaging data, accurately eliminating artifacts caused by such systematic errors and significantly improving image clarity and diagnostic accuracy.
[0008] Optionally, obtain the acquisition channel of the hardware coil; Based on the acquisition channels, the reference data is grouped to obtain channel phase data sets, and the total number of the channel phase data sets is consistent with the number of acquisition channels; Obtain the base point phase of the channel phase data set; A phase matrix is generated based on the channel phase data set; The phase matrix is compensated to obtain a compensated phase matrix; The phase compensation amount is obtained based on the compensation phase matrix and the base point phase.
[0009] By employing the above technical solution and grouping the reference data according to the hardware acquisition channels, the unique phase error of each independent channel can be precisely identified and separated, avoiding the mutual confusion of errors between channels. The resulting phase compensation is channel-specific, effectively correcting artifacts caused by channel inconsistencies, improving image uniformity, and enhancing the overall quality of multi-channel imaging.
[0010] Optionally, the mean of the channel phase data set is calculated to obtain the phase mean; Calculate the difference between the phase matrix and the mean phase value to obtain the difference phase matrix; The difference phase matrix is subjected to low-pass filtering to obtain the filtered phase matrix; The compensation phase matrix is obtained by calculating the sum of the filtered phase matrix and the phase mean.
[0011] By employing the above technical solution and performing low-pass filtering on the difference phase matrix, high-frequency and unstable phase fluctuation interference caused by random noise, patient micro-movements, etc., can be effectively filtered out. This step preserves the low-frequency phase components that reflect the stable drift of the system hardware itself, making the final compensated phase matrix more accurate.
[0012] Optionally, the period of the low-pass filtering process is the period of the radio frequency pulse, and the cutoff frequency is 1Hz to 2Hz.
[0013] Optionally, the ratio of the lengths of the first time period to the length of the second time period is calculated to obtain a proportionality coefficient; Calculate the difference between the compensation phase matrix and the base point phase to obtain the difference phase matrix; The phase compensation amount is obtained by dividing the difference phase matrix by the scaling factor.
[0014] By employing the above technical solution, and by calculating the scaling factor between the first and second time periods, and scaling the difference phase matrix proportionally, the phase error measured within the reference time period can be accurately mapped and corrected to the imaging time period. This precise calibration in the time dimension ensures the accuracy of the phase compensation in time, thereby effectively eliminating time-related artifacts caused by changes in gradient timing or system state over time.
[0015] Optionally, a central layer is determined for the channel phase data set; The highest reference echo amplitude value of the central layer is selected, and the number of the highest reference echo amplitude values is consistent with the number of phase codes; The highest value of the reference echo amplitude is unwound to obtain the base point phase.
[0016] By employing the above technical solution, a stable and reliable phase reference point is established for each phase encoding step by selecting the highest amplitude point of the central layer reference echo and unwinding it to obtain the base point phase. This method avoids additional phase errors or jumps introduced by improper reference point selection, ensuring the accuracy of the starting point for subsequent phase compensation calculations, thereby effectively reducing poor image registration or residual artifacts caused by incorrect reference phase.
[0017] Optionally, the number of phase compensation amounts can be expanded to the number of sampling points of the imaging data to form a phase compensation set; The imaging data is multiplied by the phase compensation amount in the phase compensation set to obtain the compensated imaging data.
[0018] By employing the above technical solution, and expanding the phase compensation amount to the number of sampling points in the imaging data and performing dot-multiplication, precise, point-by-point phase error correction is achieved for each sampling point in the imaging data. This full-data-point compensation method ensures the thoroughness of phase correction, and can eliminate image blurring, loss of detail, or structured artifacts caused by phase errors to the greatest extent, thereby obtaining a clearer and more realistic image.
[0019] Secondly, this application provides a magnetic resonance imaging system, which adopts the following technical solution: A magnetic resonance imaging system, comprising: The acquisition module is used to acquire the first echo signal and the second echo signal; A memory for storing the program of the magnetic resonance imaging method; The processor and the program in the memory can be loaded and executed by the processor to implement the magnetic resonance imaging method.
[0020] By employing the above technical solution and using the first echo signal without phase-coded gradient as reference data, stable phase errors caused by system hardware can be directly and specifically captured and separated. Subsequently, the phase compensation amount obtained from this reference data is used to correct the imaging data, accurately eliminating artifacts caused by such systematic errors and significantly improving image clarity and diagnostic accuracy.
[0021] Thirdly, this application provides a smart terminal, which adopts the following technical solution: A smart terminal includes a memory and a processor, wherein the memory stores a computer program that can be loaded by the processor and execute the method described in any one of the above.
[0022] Fourthly, this application provides a computer storage medium capable of storing corresponding programs, which facilitates the elimination of artifacts in magnetic resonance images, and adopts the following technical solution: A computer-readable storage medium storing a computer program that can be loaded by a processor and executed by any of the above-described magnetic resonance imaging methods.
[0023] In summary, this application includes at least one of the following beneficial technical effects: 1. By acquiring the first echo signal without phase-coded gradient as reference data, stable phase errors caused by system hardware can be directly and specifically captured and separated. Subsequently, the phase compensation amount obtained from this reference data is used to correct the imaging data, which can accurately eliminate artifacts caused by such systematic errors and significantly improve image clarity and diagnostic accuracy. 2. By grouping reference data according to the hardware acquisition channels, the unique phase error of each independent channel can be precisely identified and separated, avoiding the mutual confusion of errors between channels. The phase compensation amount generated in this way is channel-specific, which can effectively correct artifacts caused by channel inconsistencies, improve image uniformity, and enhance the overall quality of multi-channel imaging; 3. By performing low-pass filtering on the difference phase matrix, high-frequency and unstable phase fluctuation interference caused by random noise, patient micro-movements, etc., can be effectively filtered out. This step preserves the low-frequency phase components that reflect the stable drift of the system hardware itself, making the final compensated phase matrix more accurate. Attached Figure Description
[0024] Figure 1 This is a schematic flowchart of a magnetic resonance imaging method provided in an embodiment of this application.
[0025] Figure 2This is a timing diagram provided in an embodiment of this application.
[0026] Figure 3 This is a flowchart illustrating a method for calculating phase compensation amount provided in an embodiment of this application.
[0027] Figure 4 This is a comparative schematic diagram of a magnetic resonance image provided in an embodiment of this application.
[0028] Figure 5 This is a schematic diagram of a magnetic resonance imaging system provided in an embodiment of this application. Detailed Implementation
[0029] To make the purpose, technical solution, and advantages of this application clearer, the following description is provided in conjunction with the appendix. Figure 1 To be continued Figure 5 The present application will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the application.
[0030] This application discloses a magnetic resonance imaging method. (Refer to...) Figure 1 The method includes: Step S101: After applying the radio frequency pulse, the first echo signal within the first time period is acquired to obtain reference data. The first echo signal uses a phase-free coded gradient.
[0031] Please refer to Figure 2 The first time period is marked as TE1, and the first echo signal originates from the phase selection signal G. RO In this application, the first echo signal is the signal corresponding to the G5_1 part. The first echo signal is acquired without applying a phase encoding gradient.
[0032] Reference data is data or information extracted from the first echo signal.
[0033] Step S102: Acquire the second echo signal within the second time period to obtain imaging data. The second echo signal uses a phase-coded gradient.
[0034] In magnetic resonance imaging (MRI), an echo signal is generated by applying radio frequency (RF) pulses while a main magnetic field is applied to the human body. The RF pulse is a periodic pulse signal, with its period set as TR.
[0035] Please refer to Figure 2 The second time period is marked as TE2, and the second echo signal originates from the phase selection signal G. RO In this application, the second echo signal is the signal corresponding to the G5 part.
[0036] Imaging data is data or information extracted from the second echo signal. A phase-coded gradient is a transient, variable-intensity linear gradient magnetic field applied in a spatial direction after radio frequency pulse excitation. The phase-coded gradient can achieve spatial dimension localization encoding of the image by introducing a position-dependent, controllable phase shift to protons at different spatial locations within each signal acquisition cycle.
[0037] Step S103: Obtain the phase compensation amount based on the reference data.
[0038] In magnetic resonance imaging (MRI) devices, external stress causes periodic changes in the spatial position of the magnet's center, resulting in periodic amplitude and phase variations in the acquired data. This produces artifacts in the MRI images. The phase compensation amount in this application is used to compensate for these phase variations, thereby eliminating artifacts in the MRI images.
[0039] This embodiment discloses a method for calculating phase compensation, which includes the following steps S1031 to S1036, as detailed below: Step S1031: Obtain the acquisition channel of the hardware coil.
[0040] A hardware coil refers to the coil that generates the magnetic field on an MRI machine. A hardware coil contains multiple independent coil units, each of which can be considered a data acquisition channel. For example, a hardware coil may include 16 different data acquisition channels.
[0041] Step S1032: Group the reference data according to the acquisition channels to obtain the channel phase data set. The total number of channel phase data sets is consistent with the number of acquisition channels.
[0042] A channel phase data set is a collection of reference data from the same acquisition channel. Optionally, reference data corresponding to the same acquisition channel can be grouped into the same set to form a channel phase data set.
[0043] Step S1033: Obtain the base phase of the channel phase data set.
[0044] The base phase is the reference phase in the channel phase data set.
[0045] In one method for determining the base point phase, a central layer of the channel phase data set is determined. The highest reference echo amplitude value of the central layer is selected, and the number of highest reference echo amplitude values is consistent with the number of phase codes. The highest reference echo amplitude values are unwrapped to obtain the base point phase.
[0046] The central layer refers to the row of data where the phase coding gradient is zero or minimal. The reference echo with the highest amplitude is the data point with the largest amplitude; this data point has a high signal-to-noise ratio, and the phase measurement is relatively reliable.
[0047] Unwinding refers to phase unwinding, which is used to estimate the true continuous phase field from wrapped phase observations.
[0048] Optionally, after determining the central layer, the data at the center of the central layer can also be used as the base point phase.
[0049] Step S1034: Generate a phase matrix based on the channel phase data set.
[0050] A phase matrix is a matrix composed of data from the channel phase data set.
[0051] Step S1035: Perform compensation processing on the phase matrix to obtain the compensated phase matrix.
[0052] Optionally, the compensation process specifically includes: calculating the mean of the channel phase data set to obtain the phase mean; calculating the difference between the phase matrix and the phase mean to obtain the difference phase matrix; performing low-pass filtering on the difference phase matrix to obtain the filtered phase matrix; and calculating the sum of the filtered phase matrix and the phase mean to obtain the compensated phase matrix.
[0053] Optionally, the low-pass filtering period is the period of the RF pulse, with a cutoff frequency of 1Hz to 2Hz. The purpose of low-pass filtering is to preserve high frequencies (the frequency range of normally acquired signals) and retain only the phase data caused by stress.
[0054] Step S1036: Obtain the phase compensation amount based on the compensation phase matrix and the base point phase.
[0055] Optionally, calculate the ratio of the lengths of the first time period and the second time period to obtain the scaling factor. Calculate the difference between the compensation phase matrix and the base phase to obtain the difference phase matrix. Calculate the difference phase matrix divided by the scaling factor to obtain the phase compensation amount.
[0056] For example, if the first time period is TE1 and the second time period is TE2, then the ratio coefficient is ratio = TE1 / TE2.
[0057] Step S104: Perform phase compensation on the imaging data according to the phase compensation amount to obtain the compensated imaging data.
[0058] Optionally, the number of phase compensation values can be expanded to include the number of sampling points in the imaging data, forming a phase compensation set. The imaging data is then multiplied by the phase compensation values in the phase compensation set to obtain the compensated imaging data.
[0059] Step S105: Reconstruct the image from the compensated imaging data to obtain a magnetic resonance image.
[0060] Image reconstruction is the process of restoring imaging data into a magnetic resonance image. It's important to note that during image reconstruction, because compensated imaging data is used—the phase of the data has already been compensated—the magnetic resonance image is clearer. For details, please refer to... Figure 4 The image on the left is a magnetic resonance image formed from uncompensated imaging data, and the image on the right is a magnetic resonance image formed from compensated imaging data.
[0061] By employing the above technical solution and using the first echo signal without phase-coded gradient as reference data, stable phase errors caused by system hardware can be directly and specifically captured and separated. Subsequently, the phase compensation amount obtained from this reference data is used to correct the imaging data, accurately eliminating artifacts caused by such systematic errors and significantly improving image clarity and diagnostic accuracy.
[0062] Based on the same inventive concept, this application provides a magnetic resonance imaging system, please refer to... Figure 5 ,include: Acquisition module 501 is used to acquire the first echo signal and the second echo signal; The memory 502 is used to store the program of the above-described magnetic resonance imaging method; The processor 503 can load and execute the program in the memory to implement the above-mentioned magnetic resonance imaging method.
[0063] By employing the above technical solution and using the first echo signal without phase-coded gradient as reference data, stable phase errors caused by system hardware can be directly and specifically captured and separated. Subsequently, the phase compensation amount obtained from this reference data is used to correct the imaging data, accurately eliminating artifacts caused by such systematic errors and significantly improving image clarity and diagnostic accuracy.
[0064] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional modules is used as an example. In practical applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above. The specific working process of the system, device, and unit described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.
[0065] This application provides a computer-readable storage medium storing a computer program that can be loaded by a processor and executed as a magnetic resonance imaging method.
[0066] Computer storage media include, for example, USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, optical disks, and other media that can store program code.
[0067] Based on the same inventive concept, embodiments of this application provide a smart terminal, including a memory and a processor, wherein the memory stores a computer program that can be loaded by the processor and executed as a magnetic resonance imaging method.
[0068] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional modules is used as an example. In practical applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above. The specific working process of the system, device, and unit described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.
[0069] The above are all preferred embodiments of this application and are not intended to limit the scope of protection of this application. Any feature disclosed in this specification (including the abstract and drawings) may be replaced by other equivalent or similar features unless specifically stated otherwise. That is, unless specifically stated otherwise, each feature is only one example of a series of equivalent or similar features.
Claims
1. A magnetic resonance imaging method, characterized in that, include: After the radio frequency pulse is applied, the first echo signal within the first time period is acquired to obtain reference data. The first echo signal uses a phase-free coded gradient. The second echo signal within the second time period is acquired to obtain imaging data. The second echo signal is phase-coded gradient. Based on the reference data, the phase compensation amount is obtained; The imaging data is phase-compensated according to the phase compensation amount to obtain compensated imaging data. The compensated imaging data is used to reconstruct the image to obtain a magnetic resonance image.
2. The magnetic resonance imaging method according to claim 1, characterized in that, The step of obtaining the phase compensation amount based on the reference data includes: Obtain the acquisition channel of the hardware coil; Based on the acquisition channels, the reference data is grouped to obtain channel phase data sets, and the total number of the channel phase data sets is consistent with the number of acquisition channels; Obtain the base point phase of the channel phase data set; A phase matrix is generated based on the channel phase data set; The phase matrix is compensated to obtain a compensated phase matrix; The phase compensation amount is obtained based on the compensation phase matrix and the base point phase.
3. The magnetic resonance imaging method according to claim 2, characterized in that, The step of compensating the phase matrix to obtain a compensated phase matrix includes: Calculate the mean of the channel phase data set to obtain the phase mean; Calculate the difference between the phase matrix and the mean phase value to obtain the difference phase matrix; The difference phase matrix is subjected to low-pass filtering to obtain the filtered phase matrix; The compensation phase matrix is obtained by calculating the sum of the filtered phase matrix and the phase mean.
4. The magnetic resonance imaging method according to claim 1, characterized in that, The low-pass filtering process is based on the period of the radio frequency pulse, with a cutoff frequency of 1 Hz to 2 Hz.
5. The magnetic resonance imaging method according to claim 2, characterized in that, The step of obtaining the phase compensation amount based on the compensation phase matrix and the base point phase includes: Calculate the ratio of the length of the first time period to the length of the second time period to obtain the proportionality coefficient; Calculate the difference between the compensation phase matrix and the base point phase to obtain the difference phase matrix; The phase compensation amount is obtained by dividing the difference phase matrix by the scaling factor.
6. The magnetic resonance imaging method according to claim 2, characterized in that, The step of obtaining the base point phase of the channel phase data set includes: Determine the central layer of the channel phase data set; The highest reference echo amplitude value of the central layer is selected, and the number of the highest reference echo amplitude values is consistent with the number of phase codes; The highest value of the reference echo amplitude is unwound to obtain the base point phase.
7. The magnetic resonance imaging method according to claim 1, characterized in that, The step of performing phase compensation on the imaging data according to the phase compensation amount to obtain compensated imaging data includes: The number of phase compensation amounts is expanded to the number of sampling points of the imaging data to form a phase compensation set; The imaging data is multiplied by the phase compensation amount in the phase compensation set to obtain the compensated imaging data.
8. A magnetic resonance imaging system, characterized in that, The system is used to perform the magnetic resonance imaging method as described in any one of claims 1 to 7, comprising: The acquisition module is used to acquire the first echo signal and the second echo signal; A memory for storing the program of the magnetic resonance imaging method; The processor and the program in the memory can be loaded and executed by the processor to implement the magnetic resonance imaging method.
9. A smart terminal, characterized in that, It includes a memory and a processor, wherein the memory stores a computer program that can be loaded by the processor and executed as described in any one of claims 1 to 7.
10. A computer-readable storage medium, characterized in that, The computer program is stored that can be loaded by a processor and execute the method as described in any one of claims 1 to 7.