Magnetic resonance imaging method and device, computer equipment and magnetic resonance imaging system
By performing empty sweep on the imaging object to achieve and maintain the steady state of the gradient echo sequence, and collecting magnetic resonance signals in the steady state, the problem of low imaging efficiency in traditional technology is solved and more efficient magnetic resonance imaging is achieved.
Patent Information
- Application Number
- CN202311844810.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-27
- Publication Date
- 2025-06-27
AI Technical Summary
Traditional magnetic resonance imaging technology reduces imaging efficiency while ensuring the steady state of gradient echo sequences, resulting in low data acquisition efficiency and long imaging time.
By performing an empty sweep on the object to be imaged until the steady state of the gradient echo sequence is reached, and the empty sweep is continued to maintain a steady state; in the steady state, if a physiological trigger signal is received, a gradient echo sequence is applied to the object to be imaged, a magnetic resonance signal is collected, and the image is reconstructed based on the signal.
The imaging efficiency is improved, the time before steady-state acquisition is reduced, the acquisition efficiency of magnetic resonance signals is improved, and the magnetic resonance imaging time is greatly saved.
Smart Images
Figure CN120214663A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of imaging technologies, and particularly to a magnetic resonance imaging method, apparatus, computer device, and magnetic resonance imaging system. Background Art
[0002] Magnetic resonance imaging technology, which uses the magnetic resonance phenomenon to image an object to be imaged, has become a common medical imaging detection method and can also be used in life science research. During the imaging process using a magnetic resonance device, due to factors such as the involuntary movement and physiological activities of the object to be imaged, motion artifacts will appear in the image, which will affect the user's diagnosis and research based on the image.
[0003] In gradient echo sequence imaging technology, physiological triggering technology is usually combined to suppress motion artifacts. To ensure the imaging quality, it is necessary to collect magnetic resonance signals when the gradient echo sequence is in a steady state. However, the method in traditional technology to ensure the steady state of the gradient echo sequence will reduce the imaging efficiency. Summary of the Invention
[0004] Based on this, in view of the above technical problems, it is necessary to provide a magnetic resonance imaging method, apparatus, computer device, and magnetic resonance imaging system that can improve the imaging efficiency.
[0005] In a first aspect, this application provides a magnetic resonance imaging method, which includes:
[0006] Performing a dummy scan on the object to be imaged until the gradient echo sequence reaches a steady state, and continuously performing a dummy scan to maintain the steady state of the gradient echo sequence;
[0007] When the gradient echo sequence is in a steady state, if a physiological trigger signal is received, applying the gradient echo sequence to the object to be imaged and collecting the magnetic resonance signal of the object to be imaged;
[0008] Reconstructing the magnetic resonance image of the object to be imaged according to the magnetic resonance signal.
[0009] In one embodiment, when receiving a physiological trigger signal, applying the gradient echo sequence to the object to be imaged and collecting the magnetic resonance signal of the object to be imaged includes:
[0010] If a physiological trigger signal is received, performing a dummy scan on the object to be imaged during the trigger delay stage corresponding to the physiological trigger signal;
[0011] After the trigger delay stage ends, applying the gradient echo sequence to the object to be imaged and collecting the magnetic resonance signal of the object to be imaged.
[0012] In one embodiment, after collecting the magnetic resonance signal of the object to be imaged, the method further includes:
[0013] Perform a dummy scan on the imaging object until it is determined that the next physiological trigger signal is received.
[0014] In one embodiment, performing a dummy scan on the imaging object includes:
[0015] Apply a first radio frequency pulse to the imaging object and simultaneously apply a first slice selection gradient to the imaging object without signal acquisition.
[0016] In one embodiment, performing a dummy scan on the imaging object further includes:
[0017] After applying the first slice selection gradient to the imaging object, apply a first dephasing gradient to the imaging object.
[0018] In one embodiment, applying a gradient echo sequence to the imaging object and acquiring the magnetic resonance signal of the imaging object includes:
[0019] Apply a second radio frequency pulse to the imaging object and simultaneously apply a second slice selection gradient to the imaging object;
[0020] After a preset time period, apply a phase encoding gradient and a frequency encoding gradient to the imaging object and acquire the magnetic resonance signal of the imaging object.
[0021] In one embodiment, the method further includes:
[0022] Before applying the frequency encoding gradient to the imaging object, apply a second dephasing gradient to the imaging object;
[0023] After applying the frequency encoding gradient to the imaging object, apply a third dephasing gradient to the imaging object.
[0024] In a second aspect, an embodiment of the present application provides a magnetic resonance imaging device, which includes:
[0025] A dummy scan module for performing a dummy scan on the imaging object until the steady state of the gradient echo sequence is reached and continuously performing a dummy scan to maintain the steady state of the gradient echo sequence;
[0026] An acquisition module for, when the gradient echo sequence is in a steady state and a physiological trigger signal is received, applying a gradient echo sequence to the imaging object and acquiring the magnetic resonance signal of the imaging object;
[0027] A reconstruction module for reconstructing the magnetic resonance image of the imaging object according to the magnetic resonance signal.
[0028] In a third aspect, an embodiment of the present application provides a computer device, including a memory and a processor, where the memory stores a computer program, and when the processor executes the computer program, the steps of the method provided in the first aspect above are implemented.
[0029] In a fourth aspect, an embodiment of the present application further provides a magnetic resonance imaging system, which is used to implement the steps of the method provided in the first aspect above.
[0030] For the above magnetic resonance imaging method, device, computer device, and magnetic resonance imaging system, the method performs dummy scans on the object to be imaged until the steady state of the gradient echo sequence is reached, and continuously performs dummy scans to maintain the steady state of the gradient echo sequence; when the gradient echo sequence is in the steady state, if a physiological trigger signal is received, a gradient echo sequence is applied to the object to be imaged, and the magnetic resonance signal of the object to be imaged is collected; according to the magnetic resonance signal, the magnetic resonance image of the object to be imaged is reconstructed. In this embodiment, before receiving the physiological trigger signal, dummy scans are performed on the object to be imaged, so that magnetic resonance signals are collected when the gradient echo sequence is in the steady state. This can not only collect magnetic resonance signals when the gradient echo sequence is in the steady state and improve the imaging quality, but also does not require performing a sufficient number of dummy scans from the beginning each time after detecting the physiological trigger signal to reach the steady state of the gradient echo sequence, which can greatly save the time before steady state acquisition, thereby improving the acquisition efficiency of magnetic resonance signals and greatly saving the magnetic resonance imaging time. Description of the Drawings
[0031] Figure 1 It is a sequence diagram in the magnetic resonance imaging process in the traditional gradient echo sequence combined with physiological trigger technology in an embodiment;
[0032] Figure 2 It is a schematic diagram of the application environment of the magnetic resonance imaging method in an embodiment;
[0033] Figure 3 It is a schematic diagram of the structure of a computer device in an embodiment;
[0034] Figure 4 It is a schematic diagram of the step flow of the magnetic resonance imaging method in an embodiment;
[0035] Figure 5 It is a sequence diagram in the magnetic resonance imaging process provided by the present application in an embodiment;
[0036] Figure 6 It is a schematic diagram of the step flow of the magnetic resonance imaging method in another embodiment;
[0037] Figure 7 It is a sequence diagram in the magnetic resonance imaging process provided by the present application in another embodiment;
[0038] Figure 8 It is a sequence diagram in the magnetic resonance imaging process provided by the present application in another embodiment;
[0039] Figure 9 Schematic diagram of the step flow of a magnetic resonance imaging method in another embodiment;
[0040] Figure 10 Schematic diagram of the step flow of a magnetic resonance imaging method in another embodiment;
[0041] Figure 11 Sequence diagram during magnetic resonance imaging provided by the present application in another embodiment;
[0042] Figure 12 Sequence diagram during magnetic resonance imaging provided by the present application in another embodiment;
[0043] Figure 13 Magnitude map corresponding to a magnetic resonance image in one embodiment;
[0044] Figure 14 Phase map corresponding to a magnetic resonance image in one embodiment;
[0045] Figure 15 Schematic structural diagram of a magnetic resonance imaging device in one embodiment. Detailed implementation manners
[0046] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.
[0047] The serial numbers assigned to the components herein, such as "first", "second", etc., are only used to distinguish the described objects, and do not have any sequential or technical meanings.
[0048] First, before specifically introducing the technical solutions of the disclosed examples of the present application, the background technology or the technical evolution context based on the embodiments of the present application will be introduced. In the field of imaging technology, magnetic resonance imaging technology, which uses the magnetic resonance phenomenon to image the object to be imaged, has already been a common medical imaging detection method. During the imaging process using a magnetic resonance device, due to factors such as the involuntary movement and physiological activities of the object to be imaged, motion artifacts will appear in the imaged image, which will affect the diagnosis by medical staff based on the image. In the traditional Gradient Recalled Echo (GRE) sequence technology, a technology combined with physiological triggering is used to suppress motion artifacts. One way is to directly perform K-space data acquisition of non-GRE steady state after the physiological trigger point, and the other is to first set a reasonable number of dummy scans from the physiological trigger point to make the GRE signal reach a steady state and then perform K-space data acquisition. As Figure 1As shown, at the physiological trigger point, and after the trigger delay phase, a certain number of dummy scans are performed so that the GRE signal reaches a steady state. Data acquisition (steady-state acquisition) is started when the GRE signal reaches a steady state, until the next physiological trigger point arrives; the above process is repeated for magnetic resonance imaging. Figure 1 In the figure, RF represents the radio frequency pulse, GRO represents the readout axis (frequency encoding axis), GPE represents the phase encoding axis, GSS represents the slice selection axis, ADC represents the signal acquisition axis, and SYNC represents the physiological trigger signal axis.
[0049] For the K-space data that is not in the GRE steady state after the physiological trigger point, due to the inconsistency of the K-space data, the imaging quality is poor and the application range is small. For the solution of performing dummy scans after the physiological trigger point to reach the GRE steady state, since the number of dummy scans to reach the steady state is often more than dozens, and the time of each dummy scan is the repetition time (TR) of the GRE sequence, this will take a long time and reduce the data acquisition efficiency. Moreover, the number of dummy scans is also related to the set sequence parameters. Under some sequence parameters, the number of dummy scans will be even larger, resulting in lower data acquisition efficiency and further reducing the imaging efficiency. To this end, the present application provides a magnetic resonance imaging method.
[0050] The technical solution of the present application and how the technical solution of the present application solves the technical problems will be described in detail below with specific embodiments.
[0051] The magnetic resonance imaging method provided by the embodiments of the present application can be applied to an application scenario as Figure 2 shown. This application scenario includes a computer device 20 and a magnetic resonance device 21. The computer device 20 can communicate with the magnetic resonance device 21 through a network. The magnetic resonance device 21 is used to scan and process the object to be imaged, obtain a magnetic resonance signal, and transmit the magnetic resonance signal to the computer device 20. The computer device 20 is used to perform image reconstruction based on the magnetic resonance signal after receiving the magnetic resonance signal to obtain a magnetic resonance image of the object to be imaged. The computer device can be, but is not limited to, an industrial computer, a laptop computer, a tablet computer, and an embedded device, etc. The internal structure diagram of the computer device can be as Figure 3As shown in the figure. The computer device includes a processor, a memory, a communication interface, a display screen, and an input device connected via a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The communication interface of the computer device is used to communicate with external terminals in a wired or wireless manner, and the wireless manner can be implemented through WIFI, mobile cellular networks, NFC (Near Field Communication), or other technologies. When the computer program is executed by the processor, it implements a magnetic resonance imaging method. The display screen of the computer device can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device can be a touch layer covering the display screen, or buttons, trackballs, or touchpads provided on the housing of the computer device, or an external keyboard, touchpad, or mouse, etc.
[0052] In one embodiment, as Figure 4 shown, a magnetic resonance imaging method is provided. In this embodiment, the method is illustrated by taking its application to a computer device as an example. In this embodiment, the method includes the following steps:
[0053] Step 400: Perform a blank scan on the object to be imaged until the steady state of the gradient echo sequence is reached, and continuously perform a blank scan to maintain the steady state of the gradient echo sequence.
[0054] Gradient echo achieves focusing by using the gradient magnetic field inversion method. When magnetic resonance imaging is required, the computer device sends a control signal to the magnetic resonance device to cause the magnetic resonance device to perform a blank scan on the object to be imaged. During the blank scan, the computer device continuously detects whether the signal of the gradient echo sequence reaches the steady state. In this embodiment, there is no limitation on the specific method for detecting whether the signal of the gradient echo sequence reaches the steady state, as long as its function can be achieved.
[0055] Moreover, when the computer device detects that the signal of the gradient echo sequence is in the steady state, it will control the magnetic resonance device to continuously perform a blank scan on the object to be imaged to maintain the steady state of the gradient echo sequence.
[0056] Step 410: When the gradient echo sequence is in the steady state, if a physiological trigger signal is received, apply the gradient echo sequence to the object to be imaged and collect the magnetic resonance signal of the object to be imaged.
[0057] The physiological signal can be a real or simulated signal of physiological movements such as human and other animal breathing and heartbeat. The physiological trigger signal refers to a specific phase point of the physiological movement cycle determined by detecting according to the physiological signal, such as the end position of the rising edge of the breathing signal, the R wave position of the electrocardiogram signal, etc.
[0058] When the computer device determines that the gradient echo sequence is in a steady state, it detects in real time whether a physiological trigger signal of the object to be imaged is received. When it is detected that the object to be imaged generates a physiological trigger signal, a control signal is sent to the magnetic resonance device, so that the magnetic resonance device applies a gradient echo sequence to the object to be imaged and acquires gradient echo signals under the gradient echo sequence, that is, the magnetic resonance signals of the object to be imaged. In this embodiment, the specific form of the gradient echo sequence is not limited as long as its function can be realized.
[0059] Step 420: Reconstruct the magnetic resonance image of the object to be imaged according to the magnetic resonance signals.
[0060] After the magnetic resonance device acquires the magnetic resonance signals of the object to be imaged, it transmits the magnetic resonance signals to the computer device. The magnetic resonance signals obtained by the magnetic resonance device are electrical signals with spatial encoding information and belong to analog signals. After the computer device receives the magnetic resonance signals, it performs analog-to-digital conversion on the magnetic resonance signals to obtain digital signals; fills the digital signals into the K-space according to a preset filling method to obtain a corresponding K-space data set; and performs image reconstruction according to the K-space data set to obtain the magnetic resonance image of the object to be imaged. In this embodiment, the specific process of reconstructing the magnetic resonance image of the object to be imaged according to the magnetic resonance signals is not limited as long as its function can be realized.
[0061] In an optional embodiment, the sequence diagram provided in this embodiment based on the combination of the gradient echo sequence and the physiological trigger signal is as Figure 5 shown. It can be seen from Figure 5 that in this embodiment, background scanning is performed before the trigger point of the physiological trigger signal, and steady-state acquisition is performed after the trigger point.
[0062] The magnetic resonance imaging method provided by the embodiments of the present application performs background scanning on the object to be imaged until the steady state of the gradient echo sequence is reached, and continuously performs background scanning to maintain the steady state of the gradient echo sequence; when the gradient echo sequence is in a steady state, if a physiological trigger signal is received, a gradient echo sequence is applied to the object to be imaged, and the magnetic resonance signals of the object to be imaged are acquired; and the magnetic resonance image of the object to be imaged is reconstructed according to the magnetic resonance signals. In this embodiment, before the physiological trigger signal is received, background scanning is performed on the object to be imaged, so that when the gradient echo sequence is in a steady state, magnetic resonance signals are acquired. This can not only acquire magnetic resonance signals when the gradient echo sequence is in a steady state and improve the imaging quality, but also does not need to perform enough background scans from the beginning every time a physiological trigger signal is detected to reach the steady state of the gradient echo sequence, which can greatly save the time before steady-state acquisition, thereby improving the acquisition efficiency of magnetic resonance signals and greatly saving the magnetic resonance imaging time.
[0063] In one embodiment, as Figure 6 shown, it relates to an implementation method of applying a gradient echo sequence to an object to be imaged and collecting magnetic resonance signals of the object to be imaged when a physiological trigger signal is received. The steps of this implementation method include:
[0064] Step 600: If a physiological trigger signal is received, perform a dummy scan on the object to be imaged during the trigger delay stage corresponding to the physiological trigger signal.
[0065] After the physiological trigger signal is generated by the object to be imaged, there will be a corresponding trigger delay stage, that is, the time period from receiving the physiological processing signal to starting to collect magnetic resonance signals. The duration of the trigger delay stage can be preset by the user according to actual experience.
[0066] When the signal of the gradient echo sequence is in a steady state, if the computer device receives a physiological trigger signal generated by the object to be imaged, continue to perform a dummy scan on the object to be imaged during the trigger delay stage, and the dummy scan in this stage will maintain the steady state of the gradient echo sequence. That is to say, magnetic resonance signal acquisition is not performed during the delay stage.
[0067] Step 610: After the trigger delay stage ends, apply a gradient echo sequence to the object to be imaged and collect magnetic resonance signals of the object to be imaged.
[0068] When the trigger delay stage ends, that is, after the computer device receives the physiological trigger signal and an interval of a preset time period (the time period corresponding to the trigger delay stage), apply a gradient echo sequence to the object to be imaged and start collecting magnetic resonance signals.
[0069] In this embodiment, after receiving the physiological trigger signal, a dummy scan is performed on the object to be imaged during the trigger delay stage, which can maintain the steady state of the gradient echo sequence. Therefore, the magnetic resonance signals corresponding to the gradient echo sequence collected after the trigger delay stage are in the steady state of the gradient echo sequence, which can improve the quality of the collected magnetic resonance signals and further improve the quality of the obtained magnetic resonance images.
[0070] In one embodiment, after collecting magnetic resonance signals of the object to be imaged and before receiving the next physiological trigger signal, the magnetic resonance imaging method further includes:
[0071] Perform a dummy scan on the object to be imaged until it is determined that the next physiological trigger signal is received.
[0072] After the computer device applies a gradient echo sequence to the object to be imaged and collects magnetic resonance signals of the object to be imaged, it will continue to perform a dummy scan on the object to be imaged to maintain the steady state of the gradient echo sequence until the computer device receives the next physiological trigger signal.
[0073] In this embodiment, after collecting the magnetic resonance signals of the object to be imaged and before receiving the next physiological trigger signal, the object to be imaged is continuously scanned without signal. This can maintain the steady state of the gradient echo sequence, facilitating the subsequent collection of magnetic resonance signals in the steady state of the gradient echo sequence, thereby improving the quality of the collected magnetic resonance signals and further improving the quality of the magnetic resonance image of the object to be imaged. Moreover, since the steady state of the gradient echo sequence is always maintained, it is not necessary to perform a sufficient number of scans without signal from the beginning to make it re-enter the steady state of the gradient echo sequence, which can improve the efficiency of collecting magnetic resonance signals and thus reduce the magnetic resonance imaging time of the object to be imaged.
[0074] In an alternative embodiment, a sequence diagram based on the combination of the gradient echo sequence and the physiological trigger signal is as Figure 7 shown. Scanning without signal (trigger delay scanning without signal) is performed during the trigger delay phase after the trigger point of the physiological trigger signal; steady state acquisition is performed after the trigger delay phase until the preset number of steady state data acquisitions is reached. Reaching the preset number of steady state data acquisitions indicates the end of this steady state acquisition phase. As Figure 7 marked, the preset number of steady state data acquisitions in the steady state acquisition phase is 6 times; scanning without signal (scanning without signal after acquisition) is continued after the steady state acquisition phase until the trigger point of the next physiological cycle (the next trigger point) arrives; then the steps after the trigger point of the physiological trigger signal are sequentially executed within the next physiological cycle to collect signals from the object to be imaged until the data acquisition task is completed, that is, all magnetic resonance signals of the object to be imaged are collected.
[0075] In one embodiment, an implementation method for scanning an object to be imaged without signal includes:
[0076] Applying a first radio frequency pulse to the object to be imaged and simultaneously applying a first slice selection gradient to the object to be imaged without signal collection.
[0077] The magnetic resonance device includes gradient coils, and the gradient coils can include three gradient directions: the X-axis, the Y-axis, and the Z-axis. Applying a slice selection gradient to the object to be imaged means applying a gradient magnetic field to the target axis in the gradient coils, where the target axis can be any one of the X-axis, the Y-axis, and the Z-axis, or a combined direction of multiple axes.
[0078] The computer device sends a control signal to the magnetic resonance device. The magnetic resonance device applies a first radio frequency pulse to the object to be imaged based on this control signal, and applies a first slice selection gradient to the object to be imaged while applying the first radio frequency pulse. That is to say, the start time of the first radio frequency pulse is the same as the start time of the plateau period of the first slice selection gradient, and the end time of the first radio frequency pulse is the same as the end time of the plateau period of the first slice selection gradient. Applying the first slice selection gradient while applying the first radio frequency pulse can ensure that the first radio frequency pulse resonates with a specific slice (the slice corresponding to the slice selection gradient) to generate a magnetic resonance signal. After the magnetic resonance device applies the first radio frequency pulse and the first slice selection gradient, it does not collect the magnetic resonance signal of the object to be imaged. In this embodiment, there are no restrictions on the form of the first radio frequency pulse and the first slice selection gradient, as long as their functions can be realized.
[0079] In this embodiment, the computer device controls the magnetic resonance device to apply a first radio frequency pulse and a first slice selection gradient to the object to be imaged, so as to realize the dummy scan of the object to be imaged. In this way, the method of performing the dummy scan on the object to be imaged is simple and easy to implement.
[0080] In one embodiment, the implementation method for performing a dummy scan on the object to be imaged further includes:
[0081] After applying the first slice selection gradient to the object to be imaged, apply a first dephasing gradient to the object to be imaged.
[0082] After the computer device controls the magnetic resonance device to apply a first radio frequency pulse and a first slice selection gradient to the object to be imaged, it applies a first dephasing gradient to the object to be imaged. The first dephasing gradient can be formed by applying a gradient magnetic field in at least one gradient direction of the X-axis, Y-axis, and Z-axis of the gradient coil. In this embodiment, there are no restrictions on the form of the first dephasing gradient, as long as its function can be realized.
[0083] In an alternative embodiment, after applying the first slice selection gradient, a negative gradient is applied in the layer direction corresponding to the first slice selection gradient to refocus the signal, and this negative gradient is called the first refocusing gradient.
[0084] In this embodiment, after applying the first slice selection gradient to the object to be imaged, a first dephasing gradient is applied to the object to be imaged. This can eliminate the current transverse magnetization vector, thereby improving the quality of the collected magnetic resonance signal, and further improving the quality of the magnetic resonance image of the object to be imaged.
[0085] In an alternative embodiment, the sequence diagram for performing a dummy scan on the object to be imaged is as Figure 8As shown in the leftmost dashed box, a first radio frequency pulse is applied on the RF axis, and at the same time, a first slice selection gradient is applied on the GSS axis to generate a magnetic resonance signal; then, after the applied first radio frequency pulse is finished, a first refocusing gradient (i.e., Figure 8 the inverted triangle part after the first slice selection gradient in
[0086] In one embodiment, as shown in Figure 9 , it relates to an implementation manner of applying a gradient echo sequence to an object to be imaged and acquiring the magnetic resonance signal of the object to be imaged. The steps of this implementation manner include:
[0087] Step 900: Apply a second radio frequency pulse to the object to be imaged and, at the same time, apply a second slice selection gradient to the object to be imaged.
[0088] After the computer device receives the physiological trigger signal and sends a control signal to the magnetic resonance device, the magnetic resonance device applies a second radio frequency pulse to the object to be imaged and, at the same time, applies a second slice selection gradient to the object to be imaged. The second radio frequency pulse may be the same as or different from the first radio frequency pulse, and the second slice selection gradient may be the same as or different from the first slice selection gradient. The description of applying the second radio frequency pulse and the second slice selection gradient to the object to be imaged may refer to the specific description of the first radio frequency pulse and the first slice selection gradient applied during the dummy scan of the object to be imaged above.
[0089] In an alternative embodiment, after applying the second slice selection gradient, a negative gradient is applied in the layer direction corresponding to the second slice selection gradient to refocus the signal, and this negative gradient is called the second refocusing gradient.
[0090] Step 910: After a preset time period, apply a phase encoding gradient and a frequency encoding gradient to the object to be imaged and acquire the magnetic resonance signal of the object to be imaged.
[0091] The preset time period may be pre-set by the user. After the computer device controls the magnetic resonance device to apply the slice selection gradient to the object to be imaged for the preset time period, it applies an imaging sequence, i.e., a phase encoding gradient and a frequency encoding gradient, to the object to be imaged, and acquires the magnetic resonance signal of the object to be imaged under this imaging sequence.
[0092] The phase encoding gradient and the frequency encoding gradient may be formed by applying a gradient magnetic field in at least one gradient direction of the X axis, Y axis, and Z axis of the gradient coil. The form of the phase encoding gradient and the frequency encoding gradient in this embodiment is not limited as long as its function can be realized.
[0093] In this embodiment, the gradient echo sequence applied to the object to be imaged includes a second radio frequency pulse, a second slice selection gradient, a phase encoding gradient, and a frequency encoding gradient. The structure of this gradient echo sequence is simple and easy to implement.
[0094] In one embodiment, as Figure 10 shown, during the process of applying the gradient echo sequence to the object to be imaged, the steps of the magnetic resonance imaging method further include:
[0095] Step 101: Before applying the frequency encoding gradient to the object to be imaged, apply a second dephasing gradient to the object to be imaged.
[0096] During the process of the computer device controlling the magnetic resonance device to apply the gradient echo sequence, after applying the second radio frequency pulse and the second slice selection gradient (and the second rephasing gradient after the second slice selection gradient) to the object to be imaged, apply the phase encoding gradient and the frequency encoding gradient to the object to be imaged. Before applying the frequency encoding gradient to the object to be imaged, apply a second dephasing gradient to the object to be imaged. The applied second dephasing gradient can be before the applied phase encoding gradient, after the applied phase encoding gradient, or at the same time as the application time of the phase encoding gradient. The target axis corresponding to the second dephasing gradient is the same as the target axis corresponding to the frequency encoding gradient, and can be formed by applying a gradient magnetic field in at least one gradient direction of the X-axis, Y-axis, and Z-axis of the gradient coil. This embodiment does not limit the form of the second dephasing gradient, as long as its function can be achieved.
[0097] Step 102: After applying the frequency encoding gradient to the object to be imaged, apply a third dephasing gradient to the object to be imaged.
[0098] During the process of the computer device controlling the magnetic resonance device to apply the gradient echo sequence, after applying the frequency encoding gradient to the object to be imaged, continue to apply a third dephasing gradient to the object to be imaged. The third dephasing gradient can be formed by applying a gradient magnetic field in at least one gradient direction of the X-axis, Y-axis, and Z-axis of the gradient coil. This embodiment does not limit the form of the third dephasing gradient, as long as its function can be achieved.
[0099] The forms of the first dephasing gradient and the third dephasing gradient can be the same or different.
[0100] In this embodiment, by applying the third dephasing gradient, the residual signal can be eliminated, the accuracy of the collected magnetic resonance signal can be improved, and thus the quality of the obtained magnetic resonance image can be improved.
[0101] In an alternative embodiment, as Figure 8As shown, steady-state acquisition is signal acquisition performed when the signal of the applied gradient echo sequence is in a steady state. The gradient echo sequence includes a second radio frequency pulse applied on the RF axis; a second slice selection gradient applied on the GSS axis, and a second rephasing gradient (negative triangular part on the GSS axis) applied after the second slice selection gradient; a phase encoding gradient applied on the GPE axis (the first negative triangular part on the GPE axis); a second dephasing gradient applied on the GRO axis (the first negative trapezoidal part on the GRO axis), and a frequency encoding gradient (positive trapezoid after the second dephasing gradient); a third dephasing gradient applied on the GPE axis and the GRO axis (adjacent triangular parts on the GPE axis and the GRO axis). The second dephasing gradient is applied on the GRO axis, and the third dephasing gradient can be applied on at least one of the GPE axis, the GRO axis, and the GSS axis. When applying the frequency encoding gradient, it is necessary to turn on the analog-to-digital converter ADC to acquire the magnetic resonance signal.
[0102] In an optional embodiment, during the process of applying the gradient echo sequence to the object to be imaged, an echo signal (as shown) can be acquired simultaneously, or multiple echo signals can be acquired. Acquiring multiple echo signals can be used in multi-echo related applications, such as fat quantification calculation. Figure 8 As shown
[0103] During the acquisition of multiple echo signals, there are two acquisition modes. One is the same-polarity acquisition mode, as shown Figure 11 As shown; the other is the opposite-polarity acquisition mode, as shown Figure 12 As shown. As can be seen from Figure 11 , the same-polarity acquisition mode is to apply frequency encoding gradients with the same polarity on the GRO axis, that is, realized by two positive trapezoids on the GRO axis, and a dephasing gradient is applied between the two positive trapezoidal parts. As can be seen from Figure 12 , the opposite-polarity acquisition mode is to apply frequency encoding gradients with opposite polarities on the GRO axis, that is, realized by one positive trapezoid and one negative gradient on the GRO axis.
[0104] In an optional embodiment, the amplitude map (Figure A) corresponding to the magnetic resonance image (abdominal image) acquired and reconstructed without physiological signal triggering, and the amplitude map (Figure B) corresponding to the magnetic resonance image (abdominal image) reconstructed using the magnetic resonance imaging method provided in the embodiments of the present application are as shown Figure 13 As shown; the phase map (Figure C) corresponding to the magnetic resonance image (abdominal image) acquired and reconstructed without physiological signal triggering, and the phase map (Figure D) corresponding to the magnetic resonance image (abdominal image) reconstructed using the magnetic resonance imaging method provided in the embodiments of the present application are as shown Figure 14 As shown. As can be seen from Figure 13 And Figure 14It can be seen that the motion artifacts are obvious without physiological trigger signals (respiratory triggers), while there are no obvious motion artifacts in the amplitude map and phase map corresponding to the magnetic resonance images obtained by using the magnetic resonance imaging method provided in the embodiments of the present application.
[0105] An embodiment of the present application provides a magnetic resonance imaging method, and the steps of the method include:
[0106] Step S1: Continuously perform non-signal acquisition scanning on the object to be imaged until the steady state of the gradient echo sequence is reached, and continuously perform non-signal acquisition scanning to maintain the steady state of the gradient echo sequence;
[0107] The non-signal acquisition scanning includes applying a first radio frequency pulse, a first slice selection gradient, a first rephasing gradient, and a first dephasing gradient to the object to be imaged, and no signal acquisition is performed;
[0108] Step S2: When the gradient echo sequence is in a steady state, if no physiological trigger signal is received, continue to perform non-signal acquisition scanning on the object to be imaged; if a physiological trigger signal is received, perform non-signal acquisition scanning on the object to be imaged during the trigger delay stage corresponding to the physiological trigger signal;
[0109] Step S3: After the trigger delay stage ends, enter the steady state acquisition stage. In this stage, a second radio frequency pulse is applied to the object to be imaged, and at the same time, a second slice selection gradient and a second rephasing gradient are applied to the object to be imaged;
[0110] Step S4: After a first preset time period, apply a phase encoding gradient and a second dephasing gradient to the object to be imaged;
[0111] Step S5: After a second preset time period, apply a frequency encoding gradient to the object to be imaged and turn on the analog-to-digital converter ADC to acquire magnetic resonance signals, and then apply a third dephasing gradient to the object to be imaged;
[0112] Step S6: Execute steps S3 - S5 multiple times to perform multiple signal acquisitions on the object to be imaged until the preset number of steady state data acquisitions is reached;
[0113] Step S7: After the steady state acquisition stage ends, continuously perform non-signal acquisition scanning on the object to be imaged to maintain the steady state of the gradient echo sequence, return to execute steps S2 - S7, acquire all the magnetic resonance signals of the object to be imaged, and reconstruct the magnetic resonance image of the object to be imaged according to the magnetic resonance signals.
[0114] It should be understood that although the steps in the flowcharts involved in the above-described embodiments are sequentially shown in the direction of the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless there is a clear indication in this article, the execution of these steps has no strict order restriction, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above-described embodiments may include multiple steps or multiple stages. These steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be executed alternately or in turn with at least a part of other steps or steps or stages in other steps.
[0115] Based on the same inventive concept, an embodiment of the present application further provides a magnetic resonance imaging device for implementing the above-mentioned magnetic resonance imaging method. The solution provided by this device to solve the problem is similar to the solution described in the above method. Therefore, the specific limitations in one or more embodiments of the magnetic resonance imaging device provided below can refer to the limitations on the magnetic resonance imaging method in the above text, and will not be repeated here.
[0116] In one embodiment, as Figure 15 shown, a magnetic resonance imaging device 10 is provided, including: a dummy scan module 11, an acquisition module 12, and a reconstruction module 13, where:
[0117] The dummy scan module 11 is configured to perform a dummy scan on the object to be imaged until the steady state of the gradient echo sequence is reached, and continuously perform a dummy scan to maintain the steady state of the gradient echo sequence.
[0118] The acquisition module 12 is configured to, when the gradient echo sequence is in a steady state, if a physiological trigger signal is received, apply the gradient echo sequence to the object to be imaged and acquire the magnetic resonance signal of the object to be imaged.
[0119] The reconstruction module 13 is configured to reconstruct the magnetic resonance image of the object to be imaged according to the magnetic resonance signal.
[0120] In one embodiment, the acquisition module 12 includes a dummy scan unit and an acquisition unit. The dummy scan unit is configured to perform a dummy scan on the object to be imaged during the trigger delay stage corresponding to the physiological trigger signal if the physiological trigger signal is received; the acquisition unit is configured to apply the gradient echo sequence to the object to be imaged after the trigger delay stage ends and acquire the magnetic resonance signal of the object to be imaged.
[0121] In one embodiment, the dummy scan module 11 is further configured to perform a dummy scan on the object to be imaged after acquiring the magnetic resonance signal of the object to be imaged until it is determined that the next physiological trigger signal is received.
[0122] In one embodiment, the dummy scan module 11 is specifically configured to apply a first radio frequency pulse to the object to be imaged and simultaneously apply a first slice selection gradient to the object to be imaged without signal acquisition.
[0123] In one embodiment, the dummy scan module 11 is further specifically configured to apply a first dephasing gradient to the object to be imaged after applying the slice selection gradient to the object to be imaged.
[0124] In one embodiment, the acquisition module 12 includes an application unit. The application unit is configured to apply a second radio frequency pulse to the object to be imaged and simultaneously apply a second slice selection gradient to the object to be imaged; after a preset time period, apply a phase encoding gradient and a frequency encoding gradient to the object to be imaged and acquire the magnetic resonance signal of the object to be imaged.
[0125] In one embodiment, the application unit is further configured to apply a second dephasing gradient to the object to be imaged before applying the frequency encoding gradient to the object to be imaged; and apply a third dephasing gradient to the object to be imaged after applying the frequency encoding gradient to the object to be imaged.
[0126] Each module in the above magnetic resonance imaging device can be implemented in whole or in part by software, hardware, and their combination. The above modules can be embedded in the processor of the computer device in hardware form or independent of the processor, or stored in the memory of the computer device in software form, so that the processor can call and execute the operations corresponding to the above modules.
[0127] In one embodiment, a computer device is provided, and its internal structure diagram can be as Figure 3 shown. Those skilled in the art can understand that Figure 3 the structure shown in
[0128] is only a block diagram of some parts of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine some components, or have different component arrangements.
[0129] Perform a dummy scan on the object to be imaged until the steady state of the gradient echo sequence is reached, and continuously perform a dummy scan to maintain the steady state of the gradient echo sequence;
[0130] When the gradient echo sequence is in the steady state, if a physiological trigger signal is received, apply the gradient echo sequence to the object to be imaged and acquire the magnetic resonance signal of the object to be imaged;
[0131] Reconstruct the magnetic resonance image of the object to be imaged according to the magnetic resonance signal.
[0132] The structure of a magnetic resonance imaging system can be as follows Figure 1 shown, including a magnetic resonance device and a computer device. The computer device is used to send control signals to the magnetic resonance device to control the magnetic resonance device to perform a blank scan on the object to be imaged. During the blank scan, the computer device detects in real time whether the steady state of the gradient echo sequence is reached. After reaching the steady state of the gradient echo sequence, the magnetic resonance device continues to perform a blank scan to maintain the steady state of the gradient echo sequence; when the gradient echo sequence is in the steady state, if the computer device receives a physiological trigger signal, it sends a control signal to the magnetic resonance device to control the magnetic resonance device to apply the gradient echo sequence to the object to be imaged, collect the magnetic resonance signal of the object to be imaged, and transmit the magnetic resonance signal to the computer device; the computer device reconstructs the magnetic resonance image of the object to be imaged according to the received magnetic resonance signal.
[0133] In one embodiment, a computer device is provided, including a memory and a processor. A computer program is stored in the memory. When the processor executes the computer program, the following steps are implemented:
[0134] Perform a blank scan on the object to be imaged until the steady state of the gradient echo sequence is reached, and continue the blank scan to maintain the steady state of the gradient echo sequence;
[0135] When the gradient echo sequence is in the steady state, if a physiological trigger signal is received, apply the gradient echo sequence to the object to be imaged and collect the magnetic resonance signal of the object to be imaged;
[0136] Reconstruct the magnetic resonance image of the object to be imaged according to the magnetic resonance signal.
[0137] In one embodiment, when the processor executes the computer program, the following steps are also implemented: if a physiological trigger signal is received, perform a blank scan on the object to be imaged during the trigger delay stage corresponding to the physiological trigger signal; after the trigger delay stage ends, apply the gradient echo sequence to the object to be imaged and collect the magnetic resonance signal of the object to be imaged.
[0138] In one embodiment, when the processor executes the computer program, the following steps are also implemented: perform a blank scan on the object to be imaged until it is determined that the next physiological trigger signal is received.
[0139] In one embodiment, when the processor executes the computer program, the following steps are also implemented: apply a first radio frequency pulse to the object to be imaged and simultaneously apply a first slice selection gradient to the object to be imaged without signal acquisition.
[0140] In one embodiment, when the processor executes the computer program, the following steps are also implemented: after applying the first slice selection gradient to the object to be imaged, apply a first dephasing gradient to the object to be imaged.
[0141] In one embodiment, when the processor executes the computer program, the following steps are further implemented: applying a second radio frequency pulse to the object to be imaged and simultaneously applying a second slice selection gradient to the object to be imaged; after a preset time period, applying a phase encoding gradient and a frequency encoding gradient to the object to be imaged and acquiring the magnetic resonance signal of the object to be imaged.
[0142] In one embodiment, when the processor executes the computer program, the following steps are further implemented: before applying the frequency encoding gradient to the object to be imaged, applying a second dephasing gradient to the object to be imaged; after applying the frequency encoding gradient to the object to be imaged, applying a third dephasing gradient to the object to be imaged.
[0143] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the following steps are implemented:
[0144] Performing a dummy scan on the object to be imaged until the steady state of the gradient echo sequence is reached, and continuously performing the dummy scan to maintain the steady state of the gradient echo sequence;
[0145] When the gradient echo sequence is in the steady state, if a physiological trigger signal is received, applying the gradient echo sequence to the object to be imaged and acquiring the magnetic resonance signal of the object to be imaged;
[0146] Reconstructing the magnetic resonance image of the object to be imaged according to the magnetic resonance signal.
[0147] In one embodiment, when the computer program is executed by the processor, the following steps are further implemented: if a physiological trigger signal is received, performing a dummy scan on the object to be imaged during the trigger delay stage corresponding to the physiological trigger signal; after the trigger delay stage ends, applying the gradient echo sequence to the object to be imaged and acquiring the magnetic resonance signal of the object to be imaged.
[0148] In one embodiment, when the computer program is executed by the processor, the following steps are further implemented: performing a dummy scan on the object to be imaged until it is determined that the next physiological trigger signal is received.
[0149] In one embodiment, when the computer program is executed by the processor, the following steps are further implemented: applying a first radio frequency pulse to the object to be imaged and simultaneously applying a first slice selection gradient to the object to be imaged without signal acquisition.
[0150] In one embodiment, when the computer program is executed by the processor, the following steps are further implemented: after applying the first slice selection gradient to the object to be imaged, applying a first dephasing gradient to the object to be imaged.
[0151] In one embodiment, when the computer program is executed by a processor, the following steps are further implemented: applying a second radio frequency pulse to the object to be imaged and simultaneously applying a second slice selection gradient to the object to be imaged; after a preset time period, applying a phase encoding gradient and a frequency encoding gradient to the object to be imaged, and acquiring the magnetic resonance signal of the object to be imaged.
[0152] In one embodiment, when the computer program is executed by a processor, the following steps are further implemented: before applying a frequency encoding gradient to the object to be imaged, applying a second dephasing gradient to the object to be imaged; after applying a frequency encoding gradient to the object to be imaged, applying a third dephasing gradient to the object to be imaged.
[0153] In one embodiment, a computer program product is provided, including a computer program which, when executed by a processor, implements the following steps:
[0154] Performing a dummy scan on the object to be imaged until the steady state of the gradient echo sequence is reached, and continuously performing a dummy scan to maintain the steady state of the gradient echo sequence;
[0155] When the gradient echo sequence is in a steady state, if a physiological trigger signal is received, applying the gradient echo sequence to the object to be imaged and acquiring the magnetic resonance signal of the object to be imaged;
[0156] Reconstructing the magnetic resonance image of the object to be imaged according to the magnetic resonance signal.
[0157] In one embodiment, when the computer program is executed by a processor, the following steps are further implemented: if a physiological trigger signal is received, performing a dummy scan on the object to be imaged during the trigger delay stage corresponding to the physiological trigger signal; after the trigger delay stage ends, applying the gradient echo sequence to the object to be imaged and acquiring the magnetic resonance signal of the object to be imaged.
[0158] In one embodiment, when the computer program is executed by a processor, the following steps are further implemented: performing a dummy scan on the object to be imaged until it is determined that the next physiological trigger signal is received.
[0159] In one embodiment, when the computer program is executed by a processor, the following steps are further implemented: applying a first radio frequency pulse to the object to be imaged and simultaneously applying a first slice selection gradient to the object to be imaged, without signal acquisition.
[0160] In one embodiment, when the computer program is executed by a processor, the following steps are further implemented: after applying the first slice selection gradient to the object to be imaged, applying a first dephasing gradient to the object to be imaged.
[0161] In one embodiment, when the computer program is executed by a processor, the following steps are further implemented: applying a second radio frequency pulse to the object to be imaged and simultaneously applying a second slice selection gradient to the object to be imaged; after a preset time period, applying a phase encoding gradient and a frequency encoding gradient to the object to be imaged and acquiring the magnetic resonance signal of the object to be imaged.
[0162] In one embodiment, when the computer program is executed by a processor, the following steps are further implemented: before applying the frequency encoding gradient to the object to be imaged, applying a second dephasing gradient to the object to be imaged; after applying the frequency encoding gradient to the object to be imaged, applying a third dephasing gradient to the object to be imaged.
[0163] Those of ordinary skill in the art can understand that all or part of the processes of implementing the methods in the above embodiments can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above methods. Among them, any reference to a memory, a database, or other media provided in the various embodiments of the present application can include at least one of non-volatile and volatile memories. Non-volatile memories can include read-only memory (ROM), magnetic tapes, floppy disks, flash memories, optical memories, high-density embedded non-volatile memories, resistive random access memories (ReRAM), magnetoresistive random access memories (MRAM), ferroelectric random access memories (FRAM), phase change memories (PCM), graphene memories, etc. Volatile memories can include random access memory (RAM) or external cache memories, etc. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc. The databases involved in the various embodiments provided in the present application can include at least one of relational databases and non-relational databases. Non-relational databases can include distributed databases based on blockchains, etc., without limitation. The processors involved in the various embodiments provided in the present application can be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, data processing logics based on quantum computing, etc., without limitation.
[0164] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.
[0165] The above-described embodiments merely represent several implementation manners of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the appended claims.
Claims
1. A magnetic resonance imaging method, characterized in that, The method includes: Performing a dummy scan on the object to be imaged until the steady state of the gradient echo sequence is reached, and continuously performing the dummy scan to maintain the steady state of the gradient echo sequence; When the gradient echo sequence is in the steady state, if a physiological trigger signal is received, applying the gradient echo sequence to the object to be imaged and acquiring the magnetic resonance signal of the object to be imaged; Reconstructing the magnetic resonance image of the object to be imaged according to the magnetic resonance signal.
2. The method according to claim 1, wherein The step of, when a physiological trigger signal is received, applying a gradient echo sequence to the object to be imaged and acquiring the magnetic resonance signal of the object to be imaged includes: When a physiological trigger signal is received, performing a dummy scan on the object to be imaged during the trigger delay stage corresponding to the physiological trigger signal; After the trigger delay stage ends, applying the gradient echo sequence to the object to be imaged and acquiring the magnetic resonance signal of the object to be imaged.
3. The method according to claim 1, wherein After acquiring the magnetic resonance signal of the object to be imaged, the method further includes: Performing a dummy scan on the object to be imaged until it is determined that the next physiological trigger signal is received.
4. The method according to any one of claims 1-3, characterized in that, Performing a dummy scan on the object to be imaged includes: Applying a first radio frequency pulse to the object to be imaged and simultaneously applying a first slice selection gradient to the object to be imaged without signal acquisition.
5. The method according to claim 4, wherein Performing a dummy scan on the object to be imaged further includes: After applying the first slice selection gradient to the object to be imaged, applying a first dephasing gradient to the object to be imaged.
6. The method according to any one of claims 1 to 3, characterized in that, Applying the gradient echo sequence to the object to be imaged and acquiring the magnetic resonance signal of the object to be imaged includes: Applying a second radio frequency pulse to the object to be imaged and simultaneously applying a second slice selection gradient to the object to be imaged; After a preset time period, applying a phase encoding gradient and a frequency encoding gradient to the object to be imaged and acquiring the magnetic resonance signal of the object to be imaged.
7. The method according to claim 6, wherein The method further includes: Before applying the frequency encoding gradient to the object to be imaged, applying a second dephasing gradient to the object to be imaged; After applying the frequency encoding gradient to the object to be imaged, applying a third dephasing gradient to the object to be imaged.
8. A magnetic resonance imaging apparatus, characterized in that, The apparatus includes: A dummy scan module for performing a dummy scan on the object to be imaged until the steady state of the gradient echo sequence is reached, and continuously performing the dummy scan to maintain the steady state of the gradient echo sequence; An acquisition module for, when the gradient echo sequence is in the steady state, if a physiological trigger signal is received, applying the gradient echo sequence to the object to be imaged and acquiring the magnetic resonance signal of the object to be imaged; A reconstruction module for reconstructing the magnetic resonance image of the object to be imaged according to the magnetic resonance signal.
9. A computer device, comprising a memory and a processor, the memory storing a computer program, characterized in that, When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.
10. A magnetic resonance imaging system, characterized in that, The magnetic resonance imaging system is used to implement the steps of the method according to any one of claims 1 to 7.