Magnetic Resonance Non-Enhanced Angiography Method, Apparatus and Computer Device

Abstract

The present application discloses a magnetic resonance non-contrast angiography method, apparatus and computer device, which relate to the field of medical imaging technology and can improve the diagnostic value of magnetic resonance angiography. The method includes: applying a combined pulse to the region to be imaged based on the non-selective water excitation pulse in the modified T2 magnetization preparation module, controlling the longitudinal magnetization vector of the fat signal to be opposite to the direction of the main magnetic field, and the direction of the longitudinal magnetization vector of the water signal to be the same as the direction of the main magnetic field, so as to obtain water signals with different transverse magnetization vectors, where the water signals include arterial signals and venous signals; using a three-dimensional fast gradient echo sequence to perform signal acquisition to obtain water signals corresponding to multiple echo time points; and obtaining a non-contrast angiography image containing at least arterial characteristics and venous characteristics according to the water signals corresponding to multiple echo time points. The present application is applicable to large-range angiography based on non-contrast-enhanced magnetic resonance.

Description

Technical Field

[0001] This application relates to the field of medical imaging technology, and particularly to a non-contrast-enhanced magnetic resonance angiography method, apparatus, and computer device. Background Art

[0002] Magnetic resonance imaging (MRI) is one of the main imaging modalities in modern medical imaging and is widely used in medical imaging. Magnetic resonance angiography (MRA) is an important application in MRI practice. MRA can be divided into contrast-enhanced magnetic resonance angiography (CE-MRA) and non-contrast-enhanced magnetic resonance angiography (NCE-MRA). CE-MRA greatly enhances the signal of inflowing blood through the T1 shortening effect of gadolinium, improving the quality of angiography. After continuous improvement, CE-MRA is applied to almost all anatomical regions. However, the materials and injection costs of CE-MRA are high, and there are safety issues with gadolinium contrast agents. NCE-MRA methods include traditional methods such as time-of-flight (TOF), phase-contrast MRA (PC-MRA), etc., and also newly developed methods such as flow-encoding methods, spin-labeling methods, and relaxation-based methods. In contrast, NCE-MRA does not use contrast agents, has lower costs, and higher safety.

[0003] The relaxation-based NCE-MRA method does not require subtraction, so it has a certain resistance to mild motion. However, this method has poor suppression effect on background tissue, and when pursuing a better suppression effect on background tissue, it will cause signal loss of collateral arteries and there are artifacts in large-field imaging. Summary of the Invention

[0004] In view of this, this application provides a non-contrast-enhanced magnetic resonance angiography method, apparatus, and computer device, mainly aiming to solve the technical problems that the existing relaxation-based NCE-MRA method has poor suppression effect on background tissue, causes signal loss of collateral arteries when pursuing a better suppression effect on background tissue, and has artifacts in large-field imaging.

[0005] According to one aspect of this application, a non-contrast-enhanced magnetic resonance angiography method is provided. The method includes:

[0006] Applying a combined pulse to the region to be imaged based on the non-selective water excitation pulse in the modified T2 magnetization preparation module, controlling the longitudinal magnetization vector of the fat signal to be opposite to the direction of the main magnetic field, and the direction of the longitudinal magnetization vector of the water signal to be the same as the direction of the main magnetic field, to obtain water signals with different transverse magnetization vectors. The water signals include arterial signals and venous signals;

[0007] When the longitudinal vector of the fat signal reaches zero, signal acquisition is performed using a three-dimensional fast gradient echo sequence to obtain water signals corresponding to multiple echo time points;

[0008] Based on the water signals corresponding to multiple echo time points, a non-enhanced vascular image including at least arterial features and venous features is obtained.

[0009] According to another aspect of the present application, a device for magnetic resonance non-enhanced vascular imaging is provided. The device includes:

[0010] A magnetization preparation module that applies a combined pulse to the area to be imaged based on the non-selective water excitation pulse in the modified T2 magnetization preparation module, controls the longitudinal magnetization vector of the fat signal to be opposite to the direction of the main magnetic field, and the longitudinal magnetization vector direction of the water signal to be the same as the main magnetic field, to obtain water signals with different transverse magnetization vectors. The water signals include arterial signals, venous signals, and muscle signals;

[0011] A sequence acquisition module that, when the longitudinal vector of the fat signal reaches zero, performs signal acquisition using a three-dimensional fast gradient echo sequence to obtain water signals corresponding to multiple echo time points;

[0012] A reconstruction imaging module that, based on the water signals corresponding to multiple echo time points, obtains a non-enhanced vascular image including at least arterial features and venous features.

[0013] According to yet another aspect of the present application, a computer device is provided, including a storage medium, a processor, and a computer program stored on the storage medium and executable on the processor. When the processor executes the program, the above-mentioned magnetic resonance non-enhanced vascular imaging method is implemented.

[0014] With the above technical solution, the magnetic resonance non-contrast-enhanced angiography method, device, and computer device provided by this application, compared with the existing relaxation-based NCE-MRA technical solution, this application applies a combined pulse to the area to be imaged based on the non-selective water excitation pulse in the modified T2 magnetization preparation module, controls the longitudinal magnetization vector of the fat signal to be opposite to the direction of the main magnetic field, and the direction of the longitudinal magnetization vector of the water signal to be the same as the direction of the main magnetic field, obtaining arterial and venous signals with different transverse magnetization vectors. And when the longitudinal vector of the fat signal reaches zero, a three-dimensional fast gradient echo sequence is used for signal acquisition to obtain water signals corresponding to multiple echo time points. According to the water signals corresponding to the multiple echo time points collected, a non-contrast-enhanced vascular image containing at least arterial and venous characteristics is obtained. It can be seen that by using the non-selective water excitation pulse in the modified T2 magnetization preparation module to suppress the fat signal once and suppressing the fat signal again after collecting the water signal, the stability of fat signal suppression (fat suppression) can be effectively improved, thereby enhancing the contrast between arteries and veins, as well as between blood vessels and other background tissues, achieving the purpose of enhancing the diagnostic value of vascular imaging.

[0015] The above description is only an overview of the technical solution of this application. In order to be able to understand the technical means of this application more clearly, it can be implemented according to the content of the specification. And in order to make the above and other purposes, features, and advantages of this application more obvious and understandable, the following specifically illustrates the specific implementation manners of this application. Brief Description of the Drawings

[0016] The drawings described herein are used to provide a further understanding of this application, and constitute a part of this application. The schematic embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation to this application. In the drawings:

[0017] Figure 1 It shows a schematic flowchart of a magnetic resonance non-contrast-enhanced angiography method provided by an embodiment of this application;

[0018] Figure 2 It shows a schematic flowchart of another magnetic resonance non-contrast-enhanced angiography method provided by an embodiment of this application;

[0019] Figure 3a It shows a schematic diagram of proton evolution under the action of the modified T2 magnetization preparation module in an embodiment of this application;

[0020] Figure 3b It shows a schematic diagram of tissue relaxation curves under the action of the modified T2 magnetization preparation module in an embodiment of this application;

[0021] Figure 4 It shows a schematic structural diagram of a magnetic resonance non-contrast-enhanced angiography device provided by an embodiment of this application;

[0022] Figure 5 Shows a schematic structural diagram of another magnetic resonance non-contrast-enhanced angiography device provided by an embodiment of the present application. Detailed implementation manners

[0023] In the following, the present application will be described in detail with reference to the accompanying drawings and in combination with embodiments. It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0024] The basic principle of Magnetic Resonance Imaging (MRI) is to utilize the magnetic resonance phenomenon, use radio frequency excitation to excite hydrogen protons in the human body, use a gradient field for position encoding, then use a receiving coil to receive signals with position information, and finally reconstruct image information through Fourier transform. Among them, the relaxation-based NCE-MRA method, since it does not use saturation, subtraction, or inversion recovery mechanisms to explicitly remove stationary tissue signals, the depiction of blood vessels is independent of blood flow velocity, direction, or cardiac cycle, and can well depict diseased branch vessels with slow blood flow. However, the suppression of background tissue by this method is often not good. When pursuing a better background tissue suppression effect, signal loss of collateral arteries will occur, and artifacts exist in large-field imaging, and it is impossible to ensure the balance between background tissue suppression effect and sacrificed artery signals in practice. This embodiment provides a magnetic resonance non-contrast-enhanced angiography method, which can effectively improve the stability of fat signal suppression (fat suppression) by using a non-selective water excitation pulse in the modified T2 magnetization preparation module to suppress the fat signal once, and suppressing the fat signal again after the water signal is acquired, thereby improving the contrast between arteries and veins, and between blood vessels and other background tissues, such as Figure 1 As shown, the above method specifically includes the following steps:

[0025] Step 101: Apply a combined pulse to the area to be imaged based on the non-selective water excitation pulse in the modified T2 magnetization preparation module, control the longitudinal magnetization vector of the fat signal to be opposite to the direction of the main magnetic field, and the longitudinal magnetization vector direction of the water signal to be the same as the main magnetic field direction, so as to obtain water signals with different transverse magnetization vectors, and the water signals include artery signals and vein signals.

[0026] In this embodiment, the modified T2 magnetization preparation module is obtained by combining the existing T2 magnetization preparation module with a non-selective water excitation pulse, that is, replacing the 90° pulse in the existing T2 magnetization preparation module with a non-selective water excitation pulse, and keeping the inversion recovery pulse unchanged. The non-selective water excitation pulse in the modified T2 magnetization preparation module is used to magnetize the water signal, so that the water signal undergoes T2 relaxation (transverse relaxation) in the xy plane. The inversion recovery pulse in the modified T2 magnetization preparation module is used to invert the fat signal, so that the fat signal undergoes T2 relaxation (longitudinal relaxation) in the z-axis direction, that is, to control the longitudinal magnetization vector of the fat signal to be opposite to the direction of the main magnetic field. Based on the different T2 relaxation times corresponding to the arterial signal and venous signal (which may also include muscle signal) belonging to the water signal, the direction of the longitudinal magnetization vector of the water signal is controlled to be the same as the main magnetic field, but the transverse magnetization vectors are different.

[0027] Among them, the non-selective water excitation pulse is a fat suppression technique that suppresses fat signals. Different from the existing frequency-selective saturation pulse (FS), it uses the characteristic that the precession frequencies of water protons and fat protons in the magnetic field are different. By designing the flip angle, phase, and the interval time between pulses of the combined pulse, only the water protons are excited, while the fat protons remain unchanged, so as to achieve the suppression of fat signals. Further, the combination of the non-selective water excitation pulse and the inversion recovery pulse in the T2 magnetization preparation module can, while suppressing the fat signal, achieve the selective inversion of the fat signal, thereby further suppressing the fat signal to obtain a better fat signal suppression effect.

[0028] Step 102: When the longitudinal vector of the fat signal reaches zero, use a three-dimensional fast gradient echo sequence to collect signals to obtain water signals corresponding to multiple echo time points.

[0029] In this embodiment, when the longitudinal vector of the fat signal reaches zero, a multi-echo three-dimensional fast gradient echo sequence (3D Turbo Field Echo, 3D TFE) is used to collect the excited water signals to obtain arterial signals and venous signals (which may also include muscle signals) with different transverse magnetization vectors. The three-dimensional fast gradient echo sequence can achieve higher inter-slice resolution, and isotropic voxel acquisition is beneficial to subsequent imaging processing, such as multi-planar reconstruction and maximum intensity projection (MIP) processing, etc.

[0030] Step 103: According to the water signals corresponding to multiple echo time points, obtain a non-enhanced vascular image that at least includes arterial characteristics and venous characteristics.

[0031] In this embodiment, based on the non-selective water excitation pulse and the inversion recovery pulse in the modified T2 magnetization preparation module, the fat signal is suppressed once, and combined with the water-fat separation algorithm, the fat signal is suppressed twice, which can effectively reduce the risk of misclassification of the DIXON water-fat separation algorithm in local areas with low signal-to-noise ratio, thereby improving the success rate of water-fat separation. It can be seen that by combining the modified T2 magnetization preparation module with the water-fat separation algorithm to suppress fat, the stability of fat signal suppression is effectively ensured.

[0032] For this embodiment, according to the above scheme, a combined pulse is applied to the region to be imaged based on the non-selective water excitation pulse in the modified T2 magnetization preparation module, controlling the longitudinal magnetization vector of the fat signal to be opposite to the direction of the main magnetic field, and the longitudinal magnetization vector direction of the water signal to be the same as the main magnetic field direction, obtaining arterial and venous signals with different transverse magnetization vectors. And when the longitudinal vector of the fat signal reaches zero, signal acquisition is performed using a three-dimensional fast gradient echo sequence to obtain water signals corresponding to multiple echo time points. According to the collected water signals corresponding to multiple echo time points, a non-enhanced vascular image containing at least arterial and venous characteristics is obtained using the two-point method water-fat separation algorithm. Compared with the existing relaxation-based NCE-MRA technical solution, in this embodiment, the method of suppressing the fat signal once using the non-selective water excitation pulse in the modified T2 magnetization preparation module and suppressing the fat signal twice using the water-fat separation algorithm can effectively improve the stability of fat signal suppression (fat suppression), thereby enhancing the contrast between arteries and veins, as well as between blood vessels and other background tissues, achieving the purpose of enhancing the diagnostic value of vascular imaging.

[0033] Further, as a refinement and extension of the specific implementation manner of the above embodiment, in order to fully illustrate the specific implementation process of this embodiment, another magnetic resonance non-enhanced vascular imaging method is provided, as Figure 2 shown, the method includes:

[0034] Step 201: Apply a first combined pulse to the region to be imaged using the non-selective water excitation pulse in the modified T2 magnetization preparation module to obtain a first water signal and a first fat signal.

[0035] To illustrate the specific implementation manner of step 201, as a preferred embodiment, step 201 may specifically include: based on the preset interval time within the first combined pulse, by controlling the water protons to be excited to the xy plane, a first water signal is obtained, and by controlling the fat protons to remain on the z-axis, a first fat signal is obtained; wherein, after the interval time, the precession phase difference between the water protons and the fat protons is an odd multiple of π.

[0036] In implementation, the first combined pulse includes two 45° excitation pulses with an interval time of τ. As Figure 3aAs shown, a first 45° excitation pulse is applied to the region to be imaged. The water protons and fat protons in the region to be imaged are both excited to the xy plane, deflected by 45°, and maintain a precessional state in the deflected direction. Here, precession refers to the situation where an atom, under the action of an electromagnetic force, in addition to spinning, its axis of rotation rotates around a certain center, that is, the axes of rotation of the water protons and fat protons rotate around the z axis. After a duration interval τ, the precessional phase difference between the water protons and fat protons is an odd multiple of π. At this time, a second 45° excitation pulse is applied to the region to be imaged. The water protons are excited to the xy plane again, and the fat protons are excited to the z-axis direction, that is, the fat protons remain unchanged. Here, τ is the time required for the precessional phase difference between the water protons and fat protons to reach an odd multiple of π. Through experiments, it is measured that the time required for the precessional phase difference to reach π is approximately 2.3 ms under the condition of a magnetic field strength of 1.5 T, and approximately 1.15 ms under the condition of a magnetic field strength of 3.0 T.

[0037] Step 202: After waiting for a preset proportion of the effective echo time, obtain the T2 relaxation distribution state of the first water signal, and the first fat signal remains unchanged.

[0038] In practice, during the process of waiting for a preset proportion of the effective echo time (TE effective ), for example, the preset proportion is 1 / 2. As Figure 3b shown, after the venous signal, arterial signal, and muscle signal in the first water signal respectively undergo T2 relaxation and dephasing due to the inhomogeneity of the static magnetic field, the transverse magnetization vectors of the venous signal, arterial signal, and muscle signal decrease along their respective relaxation curves. The transverse magnetization vector of the arterial signal decreases more slowly and has a larger value. The transverse magnetization vectors of the venous signal and muscle signal (short T2 tissues) decrease more rapidly and have smaller values. Moreover, the transverse magnetization vector of the venous signal is slightly larger than that of the muscle signal (short T2 tissue). At this time, the first fat signal remains unchanged, that is, after waiting for TE effective / 2, obtain the distribution state of different transverse magnetization vectors of the first water signal during this period, and the distribution state of the initial longitudinal magnetization vector of the first fat signal.

[0039] Step 203: Apply an inversion pulse to the region to be imaged using the selective inversion recovery pulse in the modified T2 magnetization preparation module to obtain an inverted water signal and an inverted fat signal.

[0040] In practice, taking the selective inversion recovery pulse in the modified T2 magnetization preparation module as a single refocusing pulse, that is, a single 180° inversion pulse as an example, as Figure 3a shown, apply a single 180° inversion pulse to the region to be imaged, excite the water protons to the reverse xy plane, and reverse the fat protons from the positive z-axis direction to the negative z-axis direction, that is, obtain an inverted water signal and an inverted fat signal.

[0041] Step 204: After waiting for the effective echo time of a preset ratio, obtain the T2 relaxation distribution state of the inverted water signal and the T1 relaxation distribution state of the inverted fat signal from the negative z-axis direction to the positive z-axis direction.

[0042] In implementation, as Figure 3b shown, during the waiting period of TE effective / 2, based on the magnetization vector distribution states of the first water signal and the first fat signal, the arterial signal, the venous signal, and the muscle signal continue to undergo T2 relaxation. The magnetization vector difference between the arterial signal, the venous signal, and the muscle signal continues to increase, the venous signal and the muscle signal are further suppressed, and the dephasing of water protons caused by the inhomogeneity of the static magnetic field is completed and refocused. At this time, the fat signal undergoes T1 relaxation from the negative z-axis direction to the positive z-axis direction, and the magnetization vector of the fat signal gradually decreases, and the fat signal is suppressed. That is, wait for TE effective / 2 to obtain the distribution states of different transverse magnetization vectors of the inverted water signal and the longitudinal magnetization vector of the inverted fat signal during this period.

[0043] Step 205: Apply a second combined pulse to the region to be imaged by using the non-selective water excitation pulse in the modified T2 magnetization preparation module to obtain a second water signal and a second fat signal, where the second water signal is the water signal with separated different transverse magnetization vectors.

[0044] To illustrate the specific implementation manner of step 205, as a preferred embodiment, step 205 specifically further includes: applying a combined pulse to the region to be imaged based on the non-selective water excitation pulse in the modified T2 magnetization preparation module to control the transverse magnetization vector of the fat signal to be zero.

[0045] To illustrate the specific implementation manner of step 205, as a preferred embodiment, step 205 may specifically include: based on the preset interval time in the second combined pulse, obtain a second water signal by controlling the water protons to be excited from the xy plane to the positive z-axis direction, and obtain a second fat signal by controlling the fat protons to remain in the negative z-axis direction.

[0046] In implementation, the second combined pulse is the same as the first combined pulse, as Figure 3aAs shown, a first 45° excitation pulse is applied again to the region to be imaged. The water protons are excited to the z-axis and deflected by 45°. The fat protons are excited to the xy-plane and deflected by 45°. The water protons and fat protons maintain a precessional state in the deflected direction. After maintaining an interval time τ, the precessional phase difference between the water protons and fat protons is an odd multiple of π. At this time, a second 45° excitation pulse is applied again to the region to be imaged. The water protons are excited to the positive direction of the z-axis, and the fat protons are excited to the negative direction of the z-axis. And within the second combined pulse time, the longitudinal magnetization vector of the fat signal continuously decreases. Based on the magnetization vector distribution states of the inverted water signal and the inverted fat signal, a second water signal with different transverse magnetization vectors in the positive direction of the z-axis and a second fat signal remaining in the negative direction of the z-axis and with a magnetization vector approaching zero are obtained.

[0047] As a preferred embodiment, the first combined pulse types include 1-1 type combined pulses, 1-2-1 type combined pulses, and 1-3-3-1 type combined pulses. The first combined pulse types are the same as the second combined pulse types. The selective inversion recovery pulse in the modified T2 magnetization preparation module is a single refocusing pulse, a double refocusing pulse, or a quadruple refocusing pulse. When the selective inversion recovery pulse in the modified T2 magnetization preparation module is a double refocusing pulse or a quadruple refocusing pulse, the flip angle of the first pulse and the flip angle of the last pulse in the second combined pulse are complementary angles.

[0048] Specifically, the combined pulse timing of the double refocusing pulse 1-1 type can be: 45 x -45 x -180 u -180 -y -45 x -135 -x ; the combined pulse timing of the double refocusing pulse 1-2-1 type can be: 22.5 x -45 x -22.5 x -180 y -180 -y -22.5 x -45 x -157.5 -x , where x and y are the directions during pulse emission, i.e., the RF phase. The single refocusing pulse can be an adiabatic pulse, which is not specifically limited here.

[0049] In an actual application scenario, based on the high fat suppression stability of this embodiment, it can be considered to extend the effective echo time TE at the cost of reducing the arterial signal-to-noise ratio. effective, enhancing the difference in transverse magnetization vectors between arterial signals and venous signals, as well as between vascular signals and muscle signals within the region of interest to be imaged, and prolonging the longitudinal relaxation time of fat signals to reduce the longitudinal magnetization vector of fat signals, so as to enhance the contrast between arteries and veins within the region of interest to be imaged, and the contrast between blood vessels and background tissues (such as fat and muscle) during subsequent imaging processes.

[0050] Step 206: When the longitudinal vector of the fat signal reaches zero, use a three-dimensional fast gradient echo sequence to collect signals to obtain water signals corresponding to multiple echo time points.

[0051] In implementation, after the correction T2 magnetization preparation module waits for a preset interval time d, the longitudinal vector of the fat signal reaches zero. At this time, use a gradient echo sequence containing multiple pulses with the same flip angle to collect signals to obtain water signals corresponding to multiple echo time points. During the process of waiting for the preset interval time d, blood signals, muscle signals, and fat signals undergo T1 relaxation, where the preset interval time d is the time required for the longitudinal magnetization vector of the fat signal to approach zero.

[0052] Step 207: Obtain a non-enhanced vascular image containing at least arterial features and venous features based on the water signals corresponding to multiple echo time points.

[0053] To illustrate the specific implementation manner of step 207, as a preferred embodiment, the water signals further include muscle signals. Step 207 may specifically include: adjusting the effective echo time in the correction T2 magnetization preparation module to a delayed effective echo time, and using a two-point water-fat separation algorithm to suppress the fat signals and muscle signals within the region of interest to be imaged to obtain a non-enhanced vascular image separating arterial features and venous features.

[0054] In implementation, according to the amplitude and phase map of the collected water signals, use a two-point water-fat separation algorithm to separate the water image corresponding to the water signals, and use this water image as the non-enhanced vascular image of the region of interest to be imaged. Based on the result of the first suppression of fat signals by the correction T2 magnetization preparation module, use a two-point water-fat separation algorithm to perform a second suppression of fat signals. It can be seen that by suppressing fat signals twice, the stability of fat signal suppression can be effectively improved. Based on the stable fat signal suppression state, by adjusting the extended effective echo time, the venous signals and muscle signals within the region of interest to be imaged can be further suppressed, thereby enhancing the contrast between arteries and veins, and the contrast between arteries and veins and background tissues (such as muscle), and further making this embodiment applicable to large-scale vascular imaging of the whole body, including parts such as the neck, chest, abdomen, pelvis, and limbs, but not limited to the above parts.

[0055] By applying the technical solution of this embodiment, a combined pulse is applied to the area to be imaged based on the non-selective water excitation pulse in the modified T2 magnetization preparation module, controlling the longitudinal magnetization vector of the fat signal to be opposite to the direction of the main magnetic field, and the direction of the longitudinal magnetization vector of the water signal to be the same as the main magnetic field direction, obtaining arterial and venous signals with different transverse magnetization vectors, and when the longitudinal vector of the fat signal reaches zero, using a three-dimensional fast gradient echo sequence for signal acquisition to obtain water signals corresponding to multiple echo time points. According to the water signals corresponding to the multiple echo time points collected, a non-enhanced vascular image containing at least arterial and venous characteristics is obtained by using the two-point water-fat separation algorithm. It can be seen that by using the non-selective water excitation pulse in the modified T2 magnetization preparation module to suppress the fat signal once and using the water-fat separation algorithm to suppress the fat signal twice, the stability of fat signal suppression (fat suppression) can be effectively improved, thereby improving the contrast between arteries and veins, and between blood vessels and other background tissues, achieving the purpose of enhancing the diagnostic value of vascular imaging.

[0056] Further, as Figure 1 a specific implementation of the method, an embodiment of the present application provides a magnetic resonance non-enhanced vascular imaging method device, as Figure 4 shown, specifically including: a magnetization preparation module 41, a sequence acquisition module 42, and a reconstruction imaging module 43.

[0057] The magnetization preparation module 41 can be used to apply a combined pulse to the area to be imaged based on the non-selective water excitation pulse in the modified T2 magnetization preparation module, controlling the longitudinal magnetization vector of the fat signal to be opposite to the direction of the main magnetic field, and the direction of the longitudinal magnetization vector of the water signal to be the same as the main magnetic field direction, obtaining water signals with different transverse magnetization vectors, and the water signals include arterial signals and venous signals.

[0058] The sequence acquisition module 42 can be used to perform signal acquisition using a three-dimensional fast gradient echo sequence when the longitudinal vector of the fat signal reaches zero, obtaining water signals corresponding to multiple echo time points.

[0059] The reconstruction imaging module 43 can be used to obtain a non-enhanced vascular image containing at least arterial and venous characteristics according to the water signals corresponding to multiple echo time points.

[0060] In a specific application scenario, as Figure 5 shown, the magnetization preparation module 41 can also be used to apply a combined pulse to the area to be imaged based on the non-selective water excitation pulse in the modified T2 magnetization preparation module, controlling the transverse magnetization vector of the fat signal to be zero.

[0061] In a specific application scenario, as Figure 5As shown, the magnetization preparation module 41 includes a first combined pulse unit 411, a first waiting unit 412, an inversion pulse unit 413, a second waiting unit 414, and a second combined pulse unit 415.

[0062] The first combined pulse unit 411 can be used to apply a first combined pulse to the region to be imaged by using a non-selective water excitation pulse in the modified T2 magnetization preparation module, so as to obtain a first water signal and a first fat signal.

[0063] The first waiting unit 412 can be used to obtain the T2 relaxation distribution state of the first water signal after waiting for a preset proportion of the effective echo time, and the first fat signal remains unchanged.

[0064] The inversion pulse unit 413 can be used to apply an inversion pulse to the region to be imaged by using a selective inversion recovery pulse in the modified T2 magnetization preparation module, so as to obtain an inverted water signal and an inverted fat signal.

[0065] The second waiting unit 414 can be used to obtain the T2 relaxation distribution state of the inverted water signal and the T1 relaxation distribution state of the inverted fat signal from the negative z-axis direction to the positive z-axis direction after waiting for a preset proportion of the effective echo time.

[0066] The second combined pulse unit 415 can be used to apply a second combined pulse to the region to be imaged by using a non-selective water excitation pulse in the modified T2 magnetization preparation module, so as to obtain a second water signal and a second fat signal, and the second water signal is a water signal of separated different transverse magnetization vectors.

[0067] In a specific application scenario, the types of the first combined pulse include 1-1 type combined pulse, 1-2-1 type combined pulse, and 1-3-3-1 type combined pulse, and the types of the first combined pulse are the same as those of the second combined pulse; the selective inversion recovery pulse in the modified T2 magnetization preparation module is a single refocusing pulse, a double refocusing pulse, or a quadruple refocusing pulse. When the selective inversion recovery pulse in the modified T2 magnetization preparation module is a double refocusing pulse or a quadruple refocusing pulse, the flip angle of the first pulse and the flip angle of the last pulse in the second combined pulse are complementary angles.

[0068] In a specific application scenario, the water signal further includes a muscle signal. The reconstruction imaging module 43 can specifically be used to adjust the effective echo time in the modified T2 magnetization preparation module to a delayed effective echo time, and use a two-point method water-fat separation algorithm to obtain a non-enhanced vascular image separating arterial features and venous features by suppressing the fat signal and the muscle signal in the region to be imaged.

[0069] It should be noted that for other corresponding descriptions of the various functional units involved in the magnetic resonance non-contrast angiography device provided in the embodiments of the present application, reference can be made to Figure 1 and Figure 2 for the corresponding descriptions, which will not be elaborated here.

[0070] Based on the above methods as shown in Figure 1 and Figure 2 , correspondingly, the embodiments of the present application also provide a storage medium, on which a computer program is stored, and when the program is executed by a processor, it implements the magnetic resonance non-contrast angiography method as shown in Figure 1 and Figure 2 .

[0071] Based on such an understanding, the technical solution of the present application can be embodied in the form of a software product, and the software product can be stored in a storage medium (which can be a CD-ROM, a USB flash drive, a mobile hard disk, etc.), including several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in the various implementation scenarios of the present application.

[0072] Based on the above methods as shown in Figure 1 , Figure 2 , as well as the virtual device embodiments shown in Figure 4 , Figure 5 , in order to achieve the above object, the embodiments of the present application also provide a computer device, which can specifically be a personal computer, a server, a network device, etc. The entity device includes a storage medium and a processor; the storage medium is used to store a computer program; the processor is used to execute the computer program to implement the magnetic resonance non-contrast angiography method as shown in Figure 1 and Figure 2 .

[0073] Optionally, the computer device may further include a user interface, a network interface, a camera, a radio frequency (RF) circuit, sensors, an audio circuit, a WI-FI module, etc. The user interface may include a display screen (Display), an input unit such as a keyboard (Keyboard), etc. Optionally, the user interface may further include a USB interface, a card reader interface, etc. The network interface may optionally include a standard wired interface, a wireless interface (such as a Bluetooth interface, a WI-FI interface), etc.

[0074] Those skilled in the art can understand that the structure of a computer device provided in this embodiment does not constitute a limitation on the entity device, and it may include more or fewer components, or combine certain components, or have different component arrangements.

[0075] The storage medium may further include an operating system and a network communication module. The operating system is a program for managing the hardware and software resources of a computer device, and supports the operation of information processing programs and other software and / or programs. The network communication module is used to implement communication between components inside the storage medium, as well as communication between other hardware and software in the entity device.

[0076] Through the description of the above embodiments, those skilled in the art can clearly understand that this application can be implemented by means of software plus a necessary general hardware platform, or can also be implemented by hardware. By applying the technical solution of this application, compared with the existing relaxation-based NCE-MRA technical solution, in this embodiment, the non-selective water excitation pulse in the modified T2 magnetization preparation module is used to suppress the fat signal once, and the fat signal is suppressed twice after the water signal is acquired. This method can effectively improve the stability of fat signal suppression (fat suppression), enhance the contrast between arteries and veins, and between blood vessels and other background tissues, so as to achieve the purpose of enhancing the diagnostic value of vascular imaging.

[0077] Those skilled in the art can understand that the drawings are only schematic diagrams of a preferred implementation scenario, and the modules or processes in the drawings are not necessarily essential for implementing this application. Those skilled in the art can understand that the modules in the device in the implementation scenario can be distributed in the device in the implementation scenario according to the description of the implementation scenario, or can be correspondingly changed and located in one or more devices different from this implementation scenario. The modules in the above implementation scenario can be combined into one module, or further split into multiple sub-modules.

[0078] The above serial numbers of this application are only for description and do not represent the advantages or disadvantages of the implementation scenarios. The above-disclosed are only several specific implementation scenarios of this application. However, this application is not limited thereto, and any changes that can be thought of by those skilled in the art should fall within the protection scope of this application.

Claims

1. A magnetic resonance non-contrast angiography method, characterized in that, Specifically, it includes: Applying a combined pulse to the region to be imaged based on the non-selective water excitation pulse in the modified T2 magnetization preparation module, controlling the longitudinal magnetization vector of the fat signal to be opposite to the direction of the main magnetic field, and the longitudinal magnetization vector of the water signal to be the same as the direction of the main magnetic field; When the longitudinal magnetization vector of the fat signal reaches zero, using a three-dimensional fast gradient echo sequence to collect signals, obtaining water signals corresponding to multiple echo time points, and the water signals include arterial signals and venous signals with different transverse magnetization vectors; Based on the water signals corresponding to multiple echo time points, obtaining a non-enhanced vascular image that at least includes arterial characteristics and venous characteristics; Among them, the water signals also include muscle signals. Obtaining a non-enhanced vascular image that at least includes arterial characteristics and venous characteristics based on the water signals corresponding to multiple echo time points specifically includes: Adjusting the effective echo time in the modified T2 magnetization preparation module to a delayed effective echo time, and using a two-point water-fat separation algorithm to suppress the fat signals and muscle signals in the region to be imaged, thereby obtaining a non-enhanced vascular image that separates arterial characteristics and venous characteristics.

2. The method according to claim 1, wherein It also includes: Applying a combined pulse to the region to be imaged based on the non-selective water excitation pulse in the modified T2 magnetization preparation module, and controlling the transverse magnetization vector of the fat signal to be zero.

3. The method according to claim 1, characterized in that The step of applying a combined pulse to the region to be imaged based on the non-selective water excitation pulse in the modified T2 magnetization preparation module and controlling the longitudinal magnetization vector of the fat signal to be opposite to the direction of the main magnetic field and the longitudinal magnetization vector direction of the water signal to be the same as the main magnetic field specifically includes: Applying a first combined pulse to the region to be imaged using the non-selective water excitation pulse in the modified T2 magnetization preparation module to obtain a first water signal and a first fat signal; Applying an inversion pulse to the region to be imaged using the selective inversion recovery pulse in the modified T2 magnetization preparation module to obtain an inverted water signal and an inverted fat signal; Applying a second combined pulse to the region to be imaged using the non-selective water excitation pulse in the modified T2 magnetization preparation module to obtain a second water signal and a second fat signal; Among them, the second water signal is a water signal with separated different transverse magnetization vectors.

4. The method according to claim 3, characterized in that The step of applying a first combined pulse to the region to be imaged using the non-selective water excitation pulse in the modified T2 magnetization preparation module to obtain a first water signal and a first fat signal specifically includes: Based on the preset interval time within the first combined pulse, by controlling the water protons to be excited to the xy plane, a first water signal is obtained, and by controlling the fat protons to remain on the z axis, a first fat signal is obtained; Among them, after the interval time lasts, the precession phase difference between the water protons and the fat protons is an odd multiple of π.

5. The method according to claim 4, wherein After the step of applying a first combined pulse to the region to be imaged using the non-selective water excitation pulse in the modified T2 magnetization preparation module to obtain a first water signal and a first fat signal, specifically, it further includes: Waiting for a preset proportion of the effective echo time to obtain the T2 relaxation distribution state of the first water signal, and the first fat signal remains unchanged; After the step of applying an inversion pulse to the region to be imaged by using the selective inversion recovery pulse in the modified T2 magnetization preparation module to obtain an inverted water signal and an inverted fat signal, the method specifically further includes: After waiting for a preset proportion of the effective echo time, obtaining the T2 relaxation distribution state of the inverted water signal and the T1 relaxation distribution state of the inverted fat signal from the negative z-axis direction to the positive z-axis direction.

6. The method according to claim 3, wherein The step of applying a second combined pulse to the region to be imaged by using the non-selective water excitation pulse in the modified T2 magnetization preparation module to obtain a second water signal and a second fat signal specifically includes: Based on the preset interval time within the second combined pulse, by controlling the water protons to be excited from the xy plane to the positive z-axis direction, a second water signal is obtained, and by controlling the fat protons to remain in the negative z-axis direction, a second fat signal is obtained.

7. The method according to claim 3, characterized in that The first combined pulse types include 1-1 type combined pulse, 1-2-1 type combined pulse, and 1-3-3-1 type combined pulse, and the first combined pulse types are the same as the second combined pulse types; The selective inversion recovery pulse in the modified T2 magnetization preparation module is a single refocusing pulse, a double refocusing pulse, or a quadruple refocusing pulse. When the selective inversion recovery pulse in the modified T2 magnetization preparation module is a double refocusing pulse or a quadruple refocusing pulse, the flip angle of the first pulse and the flip angle of the last pulse in the second combined pulse are complementary angles.

8. An apparatus for magnetic resonance non-contrast angiography, characterized in that, Specifically, it includes: A magnetization preparation module, configured to apply a combined pulse to the region to be imaged based on the non-selective water excitation pulse in the modified T2 magnetization preparation module, and control the longitudinal magnetization vector of the fat signal to be opposite to the direction of the main magnetic field, and the longitudinal magnetization vector of the water signal to be the same as the direction of the main magnetic field; A sequence acquisition module, configured to perform signal acquisition by using a three-dimensional fast gradient echo sequence when the longitudinal magnetization vector of the fat signal reaches zero, and obtain water signals corresponding to multiple echo time points, where the water signals include arterial signals and venous signals with different transverse magnetization vectors; A reconstruction imaging module, configured to obtain a non-enhanced vascular image at least including arterial characteristics and venous characteristics according to the water signals corresponding to multiple echo time points; Wherein, the water signal further includes a muscle signal, and the reconstruction imaging module is specifically configured to adjust the effective echo time in the modified T2 magnetization preparation module to a delayed effective echo time, and use a two-point method water-fat separation algorithm to obtain a non-enhanced vascular image separating arterial characteristics and venous characteristics by suppressing the fat signal and the muscle signal in the region to be imaged.

9. A computer device, comprising a storage medium, a processor, and a computer program stored on the storage medium and executable on the processor, characterized in that, When the processor executes the program, it implements the magnetic resonance non-enhanced vascular imaging method according to any one of claims 1 to 7.

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