Magnetic resonance imaging method and device, medical imaging equipment and storage medium

Abstract

The invention relates to the technical field of magnetic resonance imaging, and discloses a magnetic resonance imaging method and device, medical imaging equipment and a storage medium. The magnetic resonance imaging method is suitable for at least one heartbeat cycle, and specifically, a first pulse signal higher than a preset bandwidth threshold is applied to enhance the suppression capability of a vein signal so as to suppress the vein signal flowing into a target area. And applying a second pulse signal containing a plurality of adiabatic signals with different suppression degrees to enhance the suppression capability of the background signal so as to suppress the background signal of the target area. Then, after the resting interval has elapsed, after applying a fat suppression signal to the target region, magnetic resonance imaging data of the target region is acquired. According to the embodiment, by applying the first pulse signal higher than the preset bandwidth threshold value and the second pulse signal containing the multiple adiabatic signals with different suppression degrees, the suppression effect on the vein signal and the background signal is enhanced, and therefore the quality of magnetic resonance imaging data of the target area is improved.

Description

Technical Field

[0001] The present invention relates to the field of magnetic resonance imaging technology, and in particular to a magnetic resonance imaging method, a device, a medical imaging device and a storage medium. Background Art

[0002] Magnetic resonance imaging (MRI) is an important imaging technique in modern medical imaging and is widely used in the diagnosis of various diseases. As an important application of MRI, lower extremity vascular imaging plays a key role in the evaluation of diseases such as vascular lesions, arteriosclerosis and deep vein thrombosis.

[0003] Among the related technologies, the single shot rest interval method (QISS) is widely used. However, QISS technology still has certain limitations in clinical applications, especially in terms of background signal suppression, which leads to the need to improve the clarity of imaging and the accuracy of diagnosis. Summary of the invention

[0004] The embodiments of this specification are intended to solve at least one of the technical problems in the related art to a certain extent. To this end, the embodiments of this specification propose a magnetic resonance imaging method, apparatus, medical imaging equipment and storage medium.

[0005] The present specification provides a magnetic resonance imaging method applicable to at least one heartbeat cycle, the method comprising:

[0006] Applying a first pulse signal, the first pulse signal being used to suppress a venous signal flowing into a target area, wherein a signal bandwidth of the first pulse signal is higher than a preset bandwidth threshold;

[0007] Applying a second pulse signal, wherein the second pulse signal is used to suppress the background signal in the target area, wherein the second pulse signal includes a plurality of adiabatic signals with different suppression degrees;

[0008] After a resting interval, a fat suppression signal is applied to the target area, and then magnetic resonance imaging data of the target area is acquired.

[0009] In one embodiment, the first pulse signal includes a high-bandwidth polynomial phase-saturation pulse signal.

[0010] In one embodiment, the second pulse signal includes a non-adiabatic hyperbolic tangent pulse signal and an adiabatic hyperbolic tangent pulse signal, and a flip angle of the non-adiabatic hyperbolic tangent pulse signal is smaller than a flip angle of the adiabatic hyperbolic tangent pulse signal.

[0011] In one embodiment, the acquiring magnetic resonance imaging data of the target area includes:

[0012] The magnetic resonance imaging data of the target area is acquired by adopting a center-out encoding method.

[0013] In one embodiment, the center-out encoding method includes a dual center-out encoding method.

[0014] In one embodiment, acquiring magnetic resonance imaging data of the target area includes: applying a first imaging sequence to the target area, the first imaging sequence including a balanced steady-state free precession sequence, and the positive gradient area and the negative gradient area of ​​the balanced steady-state free precession sequence are equal.

[0015] The present specification provides a magnetic resonance imaging device suitable for at least one heartbeat cycle, the device comprising:

[0016] a venous signal suppression module, configured to apply a first pulse signal, wherein the first pulse signal is configured to suppress venous signals flowing into a target area, wherein a signal bandwidth of the first pulse signal is higher than a preset bandwidth threshold;

[0017] A background signal suppression module, used for applying a second pulse signal, wherein the second pulse signal is used for suppressing the background signal of the target area, wherein the second pulse signal includes a plurality of adiabatic signals with different suppression degrees;

[0018] The magnetic resonance imaging data acquisition module is used to acquire magnetic resonance imaging data of the target area after applying a fat suppression signal to the target area after a resting interval.

[0019] An embodiment of the present specification provides a medical imaging device, which includes: a memory, and one or more processors communicatively connected to the memory; the memory stores instructions executable by the one or more processors, and the instructions are executed by the one or more processors to enable the one or more processors to implement the steps of the method described in any of the above embodiments.

[0020] The embodiments of this specification provide a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the steps of the method described in any of the above embodiments are implemented.

[0021] An embodiment of the present specification provides a computer program product, wherein the computer program product includes instructions, and when the instructions are executed by a processor of a computer device, the computer device is enabled to perform the steps of the method described in any one of the above embodiments.

[0022] In the above-mentioned embodiment of the specification, the magnetic resonance imaging method is applicable to at least one heartbeat cycle, specifically, a first pulse signal higher than a preset bandwidth threshold is applied to enhance the ability to suppress venous signals, thereby suppressing venous signals flowing into the target area. A second pulse signal comprising multiple adiabatic signals with different degrees of suppression is applied to enhance the ability to suppress background signals, thereby suppressing the background signals of the target area. Then, after a resting interval, a fat suppression signal is applied to the target area, and magnetic resonance imaging data of the target area is collected. The above-mentioned embodiment enhances the suppression effect on venous signals and background signals by applying a first pulse signal higher than a preset bandwidth threshold and a second pulse signal comprising multiple adiabatic signals with different degrees of suppression, thereby improving the quality of magnetic resonance imaging data of the target area. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram of a magnetic resonance imaging system provided for an embodiment of the present specification;

[0024] Figure 2a A schematic diagram of a magnetic resonance imaging method provided in an embodiment of the present specification;

[0025] Figure 2b A schematic diagram of lower extremity vascular imaging provided for an embodiment of this specification;

[0026] Figure 3 A schematic diagram of a process for suppressing background signals provided in an embodiment of this specification;

[0027] Figure 4 A schematic diagram of an implementation method of dual-center outward K-space encoding provided in an embodiment of this specification;

[0028] Figure 5 A sequence diagram of a magnetic resonance imaging method provided in an embodiment of this specification;

[0029] Figure 6 A schematic diagram of a magnetic resonance imaging apparatus provided in accordance with an embodiment of the present specification. DETAILED DESCRIPTION

[0030] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0031] Magnetic resonance imaging (MRI) is an important imaging method in modern medical imaging technology and is widely used in clinical diagnosis. Its basic principle is based on the magnetic resonance phenomenon, using a strong magnetic field to align hydrogen protons in the human body. Through the excitation of radio frequency signals, these hydrogen protons resonate and release signals. Then, the magnetic field gradient is used to determine the spatial position of the signal, and the receiving coil captures the signal with position information. Finally, Fourier transform is used to process these signals to reconstruct image information.

[0032] See also Figure 1 , the magnetic resonance imaging system includes the following components: magnet, gradient coil, radio frequency transmitting coil. The spin of hydrogen nuclei in the human body can be equivalent to a small magnetic needle. In the strong magnetic field provided by the magnet, the hydrogen nuclei change from a disordered thermal equilibrium state to a state partially in the direction of the main magnetic field and partially in the opposite direction. The difference between the two forms a net magnetization vector. The hydrogen nuclei precess around the main magnetic field, and the precession frequency is proportional to the magnetic field strength. The radio frequency transmitting coil can generate excitation pulse signals and refocusing pulse signals. The gradient coil can generate layer selection gradients.

[0033] Please continue reading Figure 1 The function of the gradient power amplifier is to provide the gradient coil with a current with linear intensity change, low ripple, and fast opening and closing to generate a gradient magnetic field. The RF power amplifier can be a device that can obtain a sufficiently large RF power by amplifying the RF power generated by the oscillator in the emitter through a series of amplifications (excitation stage, intermediate stage, final stage, final power amplifier stage). The receiving unit can include an induction coil that can sense and generate a detection electrical signal and can transmit the detection electrical signal. The coil interface unit can receive the magnetic resonance imaging signal through the coil conversion device. The RF control unit is connected to the RF transmitting coil and is used to generate a RF control signal according to the current position information to control the frequency and voltage of the RF signal emitted by the RF transmitting coil. The gradient control unit can be used to correct the gradient pulse shape. The bed control unit can be used to control the movement of the bed, so that the patient can be scanned multiple times at different positions. The sequence control unit can be used to control the magnetic resonance sequence. Different combinations of RF pulses and gradient pulses can form different magnetic resonance sequences. The magnetic resonance images obtained by different magnetic resonance sequences have their own characteristics.

[0034] Magnetic resonance angiography (MRA) is an important application of magnetic resonance imaging (MRI). MRA is divided into two main types: contrast-enhanced MR Angiography (CE-MRA) and non-contrast-enhanced MR Angiography (NCE-MRA).

[0035] CE-MRA improves the quality of vascular imaging by injecting gadolinium-containing contrast agents and utilizing the T1 shortening effect of gadolinium to enhance blood signals. This technology is widely used in various anatomical regions. However, the cost of CE-MRA contrast agent materials and injection is high, and there are safety issues in the use of gadolinium contrast agents in some patients (such as those with renal insufficiency).

[0036] NCE-MRA does not use contrast agents, so it is safer and less expensive. NCE-MRA includes time-of-flight (TOF), phase contrast (PC-MRA), flow encoding, spin labeling, and relaxometry.

[0037] In lower extremity vascular imaging, CE-MRA is often used because of its fast imaging speed and high image quality. However, for patients with renal disease or poor metabolic function, the use of NCE-MRA is a more recommended option.

[0038] Common techniques in NCE-MRA include time-of-flight (TOF), single-shot resting interval (QISS), 3D TSE, FSD, etc. However, TOF is not sensitive to slow blood flow. Since the blood flow velocity in the lower extremity vessels is slow, TOF is not suitable for lower extremity vascular imaging. 3D TSE and FSD are based on subtraction technology, which improves imaging quality by collecting data twice during systole and diastole to remove background signals. Although these methods are sensitive to slow blood flow, their disadvantages are that they require two acquisitions, resulting in a longer scanning time, and artifacts may appear if the patient moves. The QISS method uses a single-shot resting interval for scanning, has a higher scanning speed, and can better capture slow blood flow. It does not rely on subtraction technology, so it can overcome some of the shortcomings of the subtraction method. However, QISS has poor background tissue signal suppression effect. The QISS method relies on intra-plane saturation pulses to suppress background tissue signals, but this effect is limited by the effectiveness of the saturation pulse.

[0039] For magnetic fields of 1.5T and below, the QISS method can effectively remove background signals because the radio frequency field is relatively uniform. However, the difficulty of removing background will increase at high fields (3T) or ultra-high fields (above 3T), which is mainly affected by two main factors. First, the inhomogeneity of the radio frequency field causes the background suppression effect to be unevenly distributed in space, and the vascular signal is submerged by the background signal, resulting in unclear display. Secondly, the inhomogeneity of the B0 field increases the saturation displacement effect, affects the accuracy of the saturation position, and thus reduces the suppression effect of background tissue. In addition, the QISS method suppresses veins through saturation pulses following the layer, but the above problems will also interfere with the effective suppression of veins, resulting in difficulties in arteriovenous separation.

[0040] Based on this, an embodiment of the present specification provides a magnetic resonance imaging method. The magnetic resonance imaging method is applicable to at least one heartbeat cycle. Specifically, a first pulse signal higher than a preset bandwidth threshold is applied to enhance the ability to suppress venous signals, thereby suppressing venous signals flowing into the target area. A second pulse signal comprising multiple adiabatic signals with different degrees of suppression is applied to enhance the ability to suppress background signals, thereby suppressing the background signals of the target area. Then, after a resting interval, a fat suppression signal is applied to the target area, and magnetic resonance imaging data of the target area is collected. The above embodiment enhances the suppression effect on venous signals and background signals by applying a first pulse signal higher than a preset bandwidth threshold and a second pulse signal comprising multiple adiabatic signals with different degrees of suppression, thereby improving the quality of magnetic resonance imaging data of the target area.

[0041] The present specification provides a magnetic resonance imaging method suitable for at least one heartbeat cycle. Figure 2a , the magnetic resonance imaging method may include the following steps:

[0042] S210 , applying a first pulse signal, where the first pulse signal is used to suppress the venous signal flowing into the target area.

[0043] Wherein, the signal bandwidth of the first pulse signal is higher than a preset bandwidth threshold.

[0044] Specifically, the first pulse signal is a high-frequency radio frequency pulse, and its bandwidth is set higher than the preset bandwidth threshold to achieve a saturation effect. The high-bandwidth first pulse signal can cover a wider spectrum range, thereby reducing the signal strength in the venous area, so as to effectively suppress the magnetic resonance signal generated by the blood flowing in the venous blood vessels, while keeping the signals of the surrounding tissues (such as arteries, muscles, etc.) unchanged, thereby reducing the imaging artifacts of the veins. Among them, the preset bandwidth threshold can be set according to the noise characteristics of the target area and the required signal quality. Therefore, in order to suppress the venous signal flowing into the target area, the first pulse signal can be applied to the telecentric area adjacent to the target area. It should be noted that while applying the first pulse signal to the telecentric area adjacent to the target area, a venous suppression imaging sequence must also be applied. Among them, the venous suppression imaging sequence includes a layer selection gradient applied in the layer selection gradient direction.

[0045] S220 , applying a second pulse signal, where the second pulse signal is used to suppress the background signal in the target area.

[0046] The second pulse signal includes a plurality of adiabatic signals with different suppression degrees.

[0047] Specifically, the second pulse signal includes multiple adiabatic signals with different suppression degrees, which are used to achieve layered signal suppression of the target area. Among them, the combination of different adiabatic signals can be flexibly adjusted according to the type and intensity of the interference source, so as to maximize the signal quality of the target area while achieving signal suppression. Therefore, adiabatic signals with different suppression degrees are applied to the target area at different time points to suppress the signal intensity of the background area in a targeted manner and reduce the interference of background noise on the final imaging result. The suppression degree of each adiabatic signal is adjusted according to the characteristics of the target area, so as to maximize the signal retention of the target area while optimizing the image quality. Therefore, in order to achieve the suppression of the background signal of the target area, a second pulse signal including multiple adiabatic signals with different suppression degrees is applied to the target area. It should be noted that when applying the second pulse signal including multiple adiabatic signals with different suppression degrees to the target area, a background suppression imaging sequence is also applied. Among them, the background suppression imaging sequence includes a layer selection gradient applied in the layer selection gradient direction.

[0048] S230 , after a resting interval, applying a fat suppression signal to the target area, and then acquiring magnetic resonance imaging data of the target area.

[0049] Specifically, after suppressing the venous signal flowing into the target area and the background signal of the target area, it is necessary to wait for a period of time. This time is called the resting interval or delay time. This interval is set to ensure that the background signal is fully suppressed while allowing hemodynamic changes in the target area, such as arterial blood flowing into the target area to form an inflow enhancement signal. Among them, the resting interval can be set according to actual conditions. After the resting interval, the fat signal will interfere with the imaging results, affecting the visualization and diagnostic accuracy of the target area. In order to reduce the interference of the fat signal on the imaging results and improve the contrast between tissues, a fat suppression signal can be applied to the target area. The fat suppression signal reduces the influence of the fat signal by interfering or suppressing the spin of the fat tissue. The fat suppression signal can reduce the influence of the fat signal on the image quality through fat saturation technology (such as selective fat suppression pulse) or by using frequency offset. In addition, in order to ensure the accuracy of imaging, the second imaging sequence can be applied to the target area synchronously with the fat suppression signal to ensure the precise control and tomography of the imaging level and ensure that the fat signal is suppressed during the imaging process. Among them, the second imaging sequence includes a layer selection gradient applied in the layer selection gradient direction. Exemplarily, the fat suppression signal may be a frequency selective saturation pulse signal (CHESS saturation pulse signal). After applying the fat suppression signal to the target area, the target area is collected using a magnetic resonance imaging sequence combined with a spatial encoding technique to obtain magnetic resonance imaging data of the target area.

[0050] In some embodiments, image reconstruction is performed on the magnetic resonance imaging data of the target region to obtain a target magnetic resonance image of the target region. Figure 2b , the target magnetic resonance image may be lower extremity vascular imaging.

[0051] Exemplarily, ECG gating is used, and after ECG gating is triggered, a first pulse signal is applied to a distal region adjacent to the target region to suppress the venous signal flowing into the target region. Then, after the venous signal is suppressed, a second pulse signal including multiple adiabatic signals with different suppression degrees is applied to the target region to suppress the background signal of the target region.

[0052] In the above-mentioned embodiment, the magnetic resonance imaging method is applicable to at least one heartbeat cycle, specifically, a first pulse signal higher than a preset bandwidth threshold is applied to enhance the ability to suppress venous signals, thereby suppressing venous signals flowing into the target area. A second pulse signal comprising multiple adiabatic signals with different degrees of suppression is applied to enhance the ability to suppress background signals, thereby suppressing the background signals of the target area. Then, after a resting interval, a fat suppression signal is applied to the target area, and magnetic resonance imaging data of the target area is collected. The above-mentioned embodiment enhances the suppression effect on venous signals and background signals by applying a first pulse signal higher than a preset bandwidth threshold and a second pulse signal comprising multiple adiabatic signals with different degrees of suppression, thereby improving the quality of magnetic resonance imaging data of the target area.

[0053] In some embodiments, the first pulse signal includes a high bandwidth polynomial phase saturation pulse signal.

[0054] Specifically, the pulse used to suppress the venous signal flowing into the target area can be a high-bandwidth polynomial phase saturation pulse signal, which has an extremely high frequency bandwidth and can effectively reduce the saturation displacement effect caused by the inhomogeneity of the B0 field. In addition, the high-bandwidth polynomial phase saturation pulse signal has rapidly changing phase and frequency characteristics, and can cover multiple frequency ranges simultaneously in a wide frequency band, thereby enhancing the suppression effect on the venous signal. Precise control of a specific frequency band is achieved through polynomial phase modulation. Its function is to improve the frequency selectivity of the signal by adjusting the phase change rate, so that the stray signal in the venous area is effectively suppressed within a certain time window, thereby improving the signal-to-noise ratio and resolution of the system.

[0055] In the above implementation, the first pulse signal includes a high-bandwidth polynomial phase saturation pulse signal, which enhances anti-interference and anti-noise capabilities and improves the effect of suppressing the venous signal flowing into the target area.

[0056] In some embodiments, the second pulse signal includes a non-adiabatic hyperbolic tangent pulse signal and an adiabatic hyperbolic tangent pulse signal, and a flip angle of the non-adiabatic hyperbolic tangent pulse signal is smaller than a flip angle of the adiabatic hyperbolic tangent pulse signal.

[0057] Specifically, the flip angle of the non-adiabatic hyperbolic tangent pulse signal is relatively small, which is smaller than the flip angle of the adiabatic hyperbolic tangent pulse signal. The non-adiabatic hyperbolic tangent pulse signal usually completes a certain flip in a short time, resulting in a non-adiabatic evolution state, that is, the pulse signal changes at a fast rate, which can effectively suppress the rapidly changing background signal. For example, the flip angle of the non-adiabatic hyperbolic tangent pulse signal can be 50°.

[0058] Compared with non-adiabatic hyperbolic tangent pulse signals, adiabatic hyperbolic tangent pulse signals have larger flip angles and slower change rates, and the changes in pulse amplitude and phase are relatively gentle. Adiabatic hyperbolic tangent pulse signals evolve slowly over a longer time scale, usually maintaining quantum state stability and avoiding over-excitation. Due to the larger flip angle, adiabatic hyperbolic tangent pulse signals are more suitable for long-term and stable suppression of background signals.

[0059] The non-adiabatic hyperbolic tangent pulse signal and the adiabatic hyperbolic tangent pulse signal work together to form an efficient signal saturation module for effectively suppressing background signals.

[0060] In the above embodiment, the second pulse signal includes a non-adiabatic hyperbolic tangent pulse signal and an adiabatic hyperbolic tangent pulse signal. The flip angle of the non-adiabatic hyperbolic tangent pulse signal is smaller than the flip angle of the adiabatic hyperbolic tangent pulse signal, which helps to improve the suppression effect of the background signal.

[0061] In some embodiments, see Figure 3 The background suppression imaging sequence includes a first suppression imaging sequence and a second suppression imaging sequence; applying the second pulse signal and the background suppression imaging sequence to the target area may include the following steps:

[0062] S310 , applying a non-adiabatic hyperbolic tangent pulse signal and a first suppression imaging sequence to the target area, so that the suppression degree of the background area is the first suppression degree.

[0063] S320 . On the basis of the first suppression degree, applying an adiabatic hyperbolic tangent pulse signal and a second suppression imaging sequence to the target area, so that the suppression degree of the background area is the second suppression degree.

[0064] The second inhibition level is greater than the first inhibition level.

[0065] Specifically, first, a non-adiabatic hyperbolic tangent pulse signal is applied to the target area, and its flip angle is set to a small value so that it does not reach the adiabatic condition. When the non-adiabatic hyperbolic tangent pulse signal acts on the target area, it selectively modulates the magnetic resonance signal of the area according to its specific frequency and amplitude characteristics. In this process, combined with the first suppression imaging sequence, the magnetic resonance signal of the background area in the target area is effectively suppressed, thereby reducing the signal intensity of the background area to the first suppression level. On this basis, an adiabatic hyperbolic tangent pulse signal is further applied, and its flip angle is set to a large value so that it reaches the adiabatic condition. In this process, combined with the second suppression imaging sequence, the signal intensity of the background area is further reduced to the second suppression level through a stronger signal suppression mechanism. Compared with the first suppression, the second suppression can provide more significant background signal suppression, thereby improving the contrast and spatial resolution of the imaging. The non-adiabatic hyperbolic tangent pulse signal and the adiabatic hyperbolic tangent pulse signal work together to form an efficient signal saturation module for effectively suppressing the magnetic resonance signal of the background area, thereby improving the signal intensity and image quality of the target area during the imaging process. Among them, the first suppression imaging sequence includes a layer selection gradient applied in the layer selection gradient direction. The second suppression imaging sequence includes a slice selection gradient applied in a slice selection gradient direction.

[0066] In the above embodiment, a non-adiabatic hyperbolic tangent pulse signal and a first suppression imaging sequence are applied to the target area, so that the suppression degree of the background area is the first suppression degree. On the basis of the first suppression degree, an adiabatic hyperbolic tangent pulse signal and a second suppression imaging sequence are applied to the target area, so that the suppression degree of the background area is the second suppression degree, thereby reducing the interference of the background area on the target area signal.

[0067] In some embodiments, acquiring magnetic resonance imaging data of the target region includes: acquiring magnetic resonance imaging data of the target region using a center-out encoding method.

[0068] Specifically, in magnetic resonance imaging (MRI), in order to efficiently collect data of the target area, a center-out encoding method can be used. The center-out encoding method starts to collect low-frequency data from the center of the frequency space (also called K space), and then gradually collects high-frequency data outward until the entire frequency space is covered. Therefore, after applying a fat suppression signal to the target area, the center-out encoding method is used to collect magnetic resonance imaging data of the target area.

[0069] In the above implementation, the magnetic resonance imaging data of the target area is collected by adopting a center-outward encoding method to improve data collection efficiency.

[0070] In some embodiments, the center-out encoding method includes a dual center-out encoding method.

[0071] Specifically, the center-outward encoding method usually includes multiple types, one of which is the dual-center-outward encoding method. During the acquisition process, the dual-center-outward encoding method not only collects data from the center of the frequency space to the outside, but also performs sampling in a dual-center manner in the early stage. Low-frequency data is collected at two different center points respectively, and then collected outward respectively to collect higher-frequency spatial data until the entire frequency space is covered. Therefore, after applying a fat suppression signal to the target area, the dual-center-outward encoding method is used to collect the magnetic resonance imaging data of the target area. Among them, the data of the k-space center of the dual-center-outward encoding method is collected at a position close to the fat suppression signal to reduce the interference of the fat signal. It should be noted that the acquisition operation of the dual-center-outward encoding method is performed once to obtain all the k-space coding rows of a single layer.

[0072] For example, see Figure 4 , Figure 4 The implementation of dual center-out K-space encoding is demonstrated.

[0073] In the above implementation manner, the center-out encoding method includes a dual center-out encoding method, which effectively reduces distortion and noise during the imaging process.

[0074] In some embodiments, acquiring magnetic resonance imaging data of a target region may include: applying a first imaging sequence to the target region, the first imaging sequence including a balanced steady-state free precession sequence, the positive gradient area and the negative gradient area of ​​the balanced steady-state free precession sequence being equal.

[0075] Specifically, an excitation pulse signal and a first imaging sequence are applied to the target area to prepare the magnetization vector so as to collect signals in the subsequent imaging sequence. The first imaging sequence includes a balanced steady-state free precession sequence (bSSFP sequence). In the bSSFP sequence, the spin system is imaged in a specific steady state (equilibrium state) by continuously applying radio frequency (RF) pulses. In each TR (repetition time) cycle, the positive gradient area and the negative gradient area are equal, so that the phases in all directions are kept completely refocused, thereby avoiding the long-term accumulation or loss of signals and reducing the risk of image distortion and signal attenuation. This design allows FID (free induction decay signal), SE (spin echo signal) and STE (stimulation echo signal) signals to be fused together to form a true equilibrium state, so that the image obtains a high signal-to-noise ratio and good contrast. In addition, the equality of the positive gradient area and the negative gradient area means that there is no continuous offset of the signal in the spatial direction, thereby avoiding image distortion or signal loss that may be caused by gradient asymmetry. It should be noted that in the process of applying the first imaging sequence, the magnetic resonance imaging data of the target area can be collected in a center-to-out encoding manner.

[0076] The balanced characteristics of the balanced steady-state free precession sequence also enable it to accurately capture rapidly changing signals such as blood flow in dynamic imaging (such as lower limb vascular imaging), and can clearly display the vascular structure and its surrounding tissues, thereby providing clinicians with more intuitive and accurate imaging information.

[0077] In the above embodiment, a first imaging sequence is applied to the target area, and the first imaging sequence includes a balanced steady-state free precession sequence. The positive gradient area and the negative gradient area of ​​the balanced steady-state free precession sequence are equal, which can maintain a steady state and improve the quality of magnetic resonance imaging data.

[0078] The embodiment of this specification also provides a Figure 5 The magnetic resonance imaging method is performed according to the imaging sequence in the embodiment of the present invention. Exemplarily, the magnetic resonance imaging method includes a vein suppression module, a background suppression module, a Fatsat module and a bSSFP readout module.

[0079] In the vein suppression module, the vein suppression imaging sequence includes a slice selection gradient G1 applied simultaneously with the high-bandwidth polynomial phase saturation pulse signal Ex in the slice selection gradient direction. In the background suppression module, the first suppression imaging sequence includes a slice selection gradient G2 applied simultaneously with the non-adiabatic hyperbolic tangent pulse signal Re1 in the slice selection gradient direction. The second suppression imaging sequence includes a slice selection gradient G3 applied simultaneously with the adiabatic hyperbolic tangent pulse signal Re2 in the slice selection gradient direction.

[0080] The Fatsat module includes a frequency selective saturation pulse signal FS and a second imaging sequence including a layer selection gradient G4 in the layer selection gradient direction. The bSSFP readout module includes an excitation pulse signal Fx and a balanced steady-state free precession sequence. Fx can be a water excitation pulse. The balanced steady-state free precession sequence includes a plurality of layer selection gradients in the layer selection gradient direction; a plurality of phase encoding gradients in the phase encoding direction; and a plurality of frequency encoding gradients in the frequency encoding direction. The positive gradient area and the negative gradient area in the three gradient directions are equal. When a positive gradient is applied in the frequency encoding direction, a dual-center outward encoding method is used to perform an acquisition operation to obtain magnetic resonance imaging data for a target area.

[0081] The present specification provides a magnetic resonance imaging device 600, which is suitable for at least one heartbeat cycle. Figure 6 The magnetic resonance imaging device 600 includes: a vein signal suppression module 610, a background signal suppression module 620, and a magnetic resonance imaging data acquisition module 630.

[0082] A venous signal suppression module 610, configured to apply a first pulse signal, wherein the first pulse signal is configured to suppress venous signals flowing into a target area, wherein a signal bandwidth of the first pulse signal is higher than a preset bandwidth threshold;

[0083] A background signal suppression module 620, configured to apply a second pulse signal, wherein the second pulse signal is configured to suppress the background signal of the target area, wherein the second pulse signal comprises a plurality of adiabatic signals with different suppression degrees;

[0084] The magnetic resonance imaging data acquisition module 630 is used to acquire magnetic resonance imaging data of the target area after applying a fat suppression signal to the target area after a resting interval.

[0085] For a detailed description of the magnetic resonance imaging apparatus, reference may be made to the above description of the magnetic resonance imaging method, which will not be repeated here.

[0086] An embodiment of the present specification provides a medical imaging device, including a memory and a processor, wherein a computer program is stored in the memory, and the processor implements the method steps in the above embodiment when executing the computer program.

[0087] An embodiment of the present specification provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the steps of the method in any of the above embodiments are implemented.

[0088] One embodiment of the present specification provides a computer program product, which includes instructions. When the instructions are executed by a processor of a computer device, the computer device can perform the steps of the method of any of the above embodiments.

[0089] It should be noted that the logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be specifically implemented in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in combination with these instruction execution systems, devices or apparatuses. For the purpose of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in combination with these instruction execution systems, devices or apparatuses. More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection portion with one or more wirings (electronic device), a portable computer disk box (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or otherwise processing in a suitable manner if necessary, and then stored in a computer memory.

Claims

1. A magnetic resonance imaging method, characterized in that: Applicable to at least one heartbeat cycle, the method comprises: Applying a first pulse signal, the first pulse signal being used to suppress a venous signal flowing into a target area, wherein a signal bandwidth of the first pulse signal is higher than a preset bandwidth threshold; Applying a second pulse signal, wherein the second pulse signal is used to suppress the background signal in the target area, wherein the second pulse signal includes a plurality of adiabatic signals with different suppression degrees; After a resting interval, a fat suppression signal is applied to the target area, and then magnetic resonance imaging data of the target area is acquired.

2. The method according to claim 1, characterized in that The first pulse signal comprises a high-bandwidth polynomial phase-saturation pulse signal.

3. The method according to claim 1, characterized in that The second pulse signal includes a non-adiabatic hyperbolic tangent pulse signal and an adiabatic hyperbolic tangent pulse signal, and a flip angle of the non-adiabatic hyperbolic tangent pulse signal is smaller than a flip angle of the adiabatic hyperbolic tangent pulse signal.

4. The method according to any one of claims 1 to 3, characterized in that: The acquiring of magnetic resonance imaging data of the target area comprises: The magnetic resonance imaging data of the target area is acquired by adopting a center-out encoding method.

5. The method according to claim 4, characterized in that The center-out encoding method includes a dual center-out encoding method.

6. The method according to any one of claims 1 to 3, characterized in that: The acquiring of magnetic resonance imaging data of the target area comprises: A first imaging sequence is applied to the target area, wherein the first imaging sequence comprises a balanced steady-state free precession sequence, wherein the positive gradient area and the negative gradient area of ​​the balanced steady-state free precession sequence are equal.

7. A magnetic resonance imaging device, characterized in that: Applicable to at least one heartbeat cycle, the device comprises: a venous signal suppression module, configured to apply a first pulse signal, wherein the first pulse signal is configured to suppress venous signals flowing into a target area, wherein a signal bandwidth of the first pulse signal is higher than a preset bandwidth threshold; A background signal suppression module, used for applying a second pulse signal, wherein the second pulse signal is used for suppressing the background signal of the target area, wherein the second pulse signal includes a plurality of adiabatic signals with different suppression degrees; The magnetic resonance imaging data acquisition module is used to acquire magnetic resonance imaging data of the target area after applying a fat suppression signal to the target area after a resting interval.

8. A medical imaging device, comprising a memory and a processor, wherein the memory stores 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 6 are implemented.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

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