CN114397612A - Magnetic resonance non-enhanced blood vessel imaging method and device and computer equipment - Google Patents

Abstract

The application discloses a magnetic resonance non-enhanced vascular imaging method, a magnetic resonance non-enhanced vascular imaging device and computer equipment, relates to the technical field of medical imaging, and can improve the diagnostic value of magnetic resonance vascular imaging. The method comprises the following steps: applying a combined pulse to a region to be imaged based on a non-selective water excitation pulse in a corrected T2 magnetization preparation module, controlling the longitudinal magnetization vector of a fat signal to be opposite to the direction of a main magnetic field, and controlling the longitudinal magnetization vector of a water signal to be the same as the direction of the main magnetic field to obtain water signals with different transverse magnetization vectors, wherein the water signals comprise arterial signals and venous signals; acquiring signals by using a three-dimensional fast gradient echo sequence to obtain water signals corresponding to a plurality of echo time points; and obtaining a non-enhanced blood vessel image at least comprising artery characteristics and vein characteristics according to the water signals corresponding to the multiple echo time points. The application is applicable to large-scale vessel imaging based on non-contrast enhanced magnetic resonance.

Description

Magnetic resonance non-enhanced vascular imaging method, device and computer equipment

technical field

The present application relates to the technical field of medical imaging, and in particular, to a magnetic resonance non-enhanced vascular imaging method, device and computer equipment.

Background technique

Magnetic resonance imaging is one of the main imaging methods in modern medical imaging, which is widely used in medical imaging, and magnetic resonance angiography is an important application in the practice of magnetic resonance imaging. Magnetic resonance angiography is divided into contrast-enhanced MR Angiography (Contrast-enhanced MR Angiography, CE-MRA) and non-contrast-enhanced MR Angiography (Non-contrast-enhanced MR Angiography, NCE-MRA). CE-MRA greatly enhances the influx signal through the T1 shortening effect of gadolinium, improving angiographic quality. After continuous improvement, CE-MRA is applied to almost all anatomical areas, but CE-MRA materials and injection costs are high, and gadolinium contrast agents have safety issues; while NCE-MRA methods include traditional methods such as time-of-flight (TOF) , phase contrast method (PC-MRA), etc., and also include newly developed methods, such as flow coding-based methods, spin labeling methods, and relaxation-based methods, etc. In contrast, NCE-MRA does not use contrast agents and costs more. lower, higher security.

The relaxation-based NCE-MRA method does not require the use of subtraction, so it has a certain resistance to mild exercise, but this method has poor suppression effect on background tissue, and when a better background tissue suppression effect is pursued It will cause the signal loss of the side branch arteries, and there is the problem of artifacts in the large field of view imaging.

SUMMARY OF THE INVENTION

In view of this, the present application provides magnetic resonance non-enhanced vascular imaging methods, devices and computer equipment, the main purpose of which is to solve the problem that the existing relaxation-based NCE-MRA methods have poor suppression effect on background tissue, and are in pursuit of better. Background Tissue suppression will cause signal loss of collateral arteries, and there is a technical problem of artefacts in large-field imaging.

According to one aspect of the present application, a magnetic resonance non-enhanced vascular imaging method is provided, the method comprising:

Based on the non-selective water excitation pulse in the modified T2 magnetization preparation module, a combined pulse is applied to the area to be imaged, and the longitudinal magnetization vector of the fat signal is controlled to be opposite to the direction of the main magnetic field, and the longitudinal magnetization vector of the water signal is in the same direction as the main magnetic field. the water signal of the magnetization vector, the water signal including the arterial signal and the venous signal;

When the longitudinal vector of the fat signal reaches zero, the 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 multiple echo time points, a non-enhanced blood vessel image including at least arterial features and vein features is obtained.

According to another aspect of the present application, a device for magnetic resonance non-enhanced vascular imaging is provided, the device comprising:

The magnetization preparation module applies combined pulses to the area to be imaged based on the non-selective water excitation pulse in the modified T2 magnetization preparation module, and 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 of the water signal to the same direction as the main magnetic field , to obtain water signals of different transverse magnetization vectors, the water signals include arterial signals, venous signals and muscle signals;

The sequence acquisition module, when the longitudinal vector of the fat signal reaches zero, uses a three-dimensional fast gradient echo sequence to perform signal acquisition to obtain water signals corresponding to multiple echo time points;

The reconstruction imaging module obtains a non-enhanced blood vessel image including at least arterial features and vein features according to the water signals corresponding to multiple echo time points.

According to yet another aspect of the present application, a computer device is provided, comprising a storage medium, a processor, and a computer program stored on the storage medium and executable on the processor, the processor implementing the above-mentioned magnetic resonance when the program is executed Non-enhanced vascular imaging methods.

With the above technical solution, the magnetic resonance non-enhanced vascular imaging method, device and computer equipment provided by the present application, compared with the existing relaxation-based NCE-MRA technical solution, the present application is based on correcting the non-selection in the T2 magnetization preparation module. The water excitation pulse applies combined pulses to the area to be imaged, 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 is the same as the main magnetic field. 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 collected water signals corresponding to multiple echo time points, A non-enhanced vascular image containing at least arterial and venous features 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 after the water signal is collected, the fat signal can be suppressed twice, which can effectively improve the fat signal suppression (fat reduction). The stability of vascular imaging improves the contrast between arteries and veins, as well as blood vessels and other background tissues, so as to enhance the diagnostic value of vascular imaging.

The above description is only an overview of the technical solution of the present application. In order to be able to understand the technical means of the present application more clearly, it can be implemented according to the content of the description, and in order to make the above-mentioned and other purposes, features and advantages of the present application more obvious and easy to understand , and the specific embodiments of the present application are listed below.

Description of drawings

The drawings described herein are used to provide further understanding of the present application and constitute a part of the present application. The schematic embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation of the present application. In the attached image:

FIG. 1 shows a schematic flowchart of a magnetic resonance non-enhanced vascular imaging method provided by an embodiment of the present application;

FIG. 2 shows a schematic flowchart of another magnetic resonance non-enhanced vascular imaging method provided by an embodiment of the present application;

Figure 3a shows a schematic diagram of proton evolution under the action of the modified T2 magnetization preparation module in the embodiment of the present application;

Fig. 3b shows a schematic diagram of the tissue relaxation curve under the action of the modified T2 magnetization preparation module in the embodiment of the present application;

FIG. 4 shows a schematic structural diagram of a magnetic resonance non-enhanced vascular imaging device provided by an embodiment of the present application;

FIG. 5 shows a schematic structural diagram of another magnetic resonance non-enhanced blood vessel imaging device provided by an embodiment of the present application.

Detailed ways

Hereinafter, the present application will be described in detail with reference to the accompanying drawings and in conjunction with the embodiments. It should be noted that the embodiments in the present application and the features of the embodiments may be combined with each other in the case of no conflict.

The basic principle of Magnetic Resonance Imaging (MRI) is to use the magnetic resonance phenomenon to excite hydrogen protons in the human body with radio frequency excitation, use the gradient field to encode the position, and then use the receiving coil to receive the signal with the position information, and finally pass the Fu Lie transform reconstructs the image information. Among them, the relaxation-based NCE-MRA method does not use saturation, subtraction or inversion recovery mechanism to explicitly remove the static tissue signal, and the delineation of blood vessels is independent of blood flow velocity, direction or cardiac cycle, and can be well delineated Slow-flowing diseased branch vessels, but this method often does not suppress the background tissue well. In pursuit of a better background tissue suppression effect, the signal loss of the collateral arteries will be caused, and there will be artifacts in the large field of view imaging, which cannot be used in practice. Ensure a balance between the effect of background tissue suppression and sacrificing arterial signal. This embodiment provides a magnetic resonance non-enhanced vascular imaging method, which can suppress the fat signal once by using the non-selective water excitation pulse in the modified T2 magnetization preparation module, and perform a second step on the fat signal after the water signal is collected. The method of secondary inhibition effectively improves the stability of fat signal inhibition (fat suppression), thereby improving the contrast between arteries and veins, as well as blood vessels and other background tissues. As shown in Figure 1, the above method specifically includes the following steps:

Step 101, applying 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 longitudinal magnetization vector direction of the water signal to be the same as the main magnetic field, Water signals with different transverse magnetization vectors are obtained, including arterial and venous signals.

In this embodiment, the modified T2 magnetization preparation module is obtained based on the combination of the existing T2 magnetization preparation module and the non-selective water excitation pulse, that is, the 90° pulse in the existing T2 magnetization preparation module is replaced by the non-selective water excitation pulse pulse, the inversion recovery pulse remains unchanged. The water signal is magnetized by the non-selective water excitation pulse in the modified T2 magnetization preparation module, so that the water signal undergoes T2 relaxation (transverse relaxation) in the xy plane. Using the inversion recovery pulse in the modified T2 magnetization preparation module, the The fat signal is inverted so that the fat signal undergoes T2 relaxation (longitudinal relaxation) in the z-axis direction, i.e. the longitudinal magnetization vector that controls the fat signal is in the opposite direction to the main magnetic field, and based on the arterial and venous signals belonging to the water signal (also Can include muscle signal) corresponding to different T2 relaxation times, the direction of the longitudinal magnetization vector of the control water signal is the same as that of the main magnetic field, but the transverse magnetization vector is different, so the arterial signal and venous signal with different transverse magnetization vectors (can also include muscle signal) are obtained. Signal).

Among them, the non-selective water excitation pulse is a fat-suppressing technology that suppresses fat signals. It is different from the existing frequency-selective saturation pulse (Fat Saturation, FS), which uses water protons and fat protons to precess the frequency in a magnetic field. Different characteristics, by designing the flip angle, phase and interval time of the combined pulses, only water protons are excited, while fat protons remain unchanged, so as to suppress the fat signal. Further, the combination of the non-selective water excitation pulse and the inversion recovery pulse in the T2 magnetization preparation module can suppress the fat signal at the same time as the selective inversion of the fat signal, thereby further suppressing the fat signal. , in order to obtain better fat signal inhibition effect.

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

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 signal. Higher inter-slice resolution can be achieved, and equal voxel acquisition is beneficial for subsequent imaging processing, such as multi-plane reconstruction and Maximum Intensity Projection (MIP) processing.

Step 103: Obtain a non-enhanced blood vessel image including at least arterial features and vein features according to the water signals corresponding to multiple echo time points.

In this embodiment, the fat signal is suppressed once based on the non-selective water excitation pulse and inversion recovery pulse in the modified T2 magnetization preparation module, and the fat signal is suppressed for the second time in combination with the water-fat separation algorithm, which can effectively reduce the amount of DIXON water. The lipid separation algorithm has the risk of misclassification in local areas with low signal-to-noise ratio, thereby improving the success rate of water-fat separation. It can be seen that the stability of fat signal suppression can be effectively ensured by modifying the T2 magnetization preparation module and the water-fat separation algorithm to combine fat reduction.

For this embodiment, according to the above scheme, the 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, and the longitudinal magnetization vector of the fat signal is controlled to be opposite to the direction of the main magnetic field, and the longitudinal magnetization vector of the water signal is controlled. The direction is the same as that of the main magnetic field, and arterial signals and venous signals with different transverse magnetization vectors are obtained, and when the longitudinal vector of the fat signal reaches zero, the three-dimensional fast gradient echo sequence is used for signal acquisition, and multiple echo time points corresponding to According to the collected water signals corresponding to multiple echo time points, a two-point water-fat separation algorithm is used to obtain a non-enhanced blood vessel image containing at least arterial features and vein features. Compared with the existing relaxation-based NCE-MRA technical solution, the present embodiment uses the non-selective water excitation pulse in the modified T2 magnetization preparation module to suppress the fat signal once, and uses the water-fat separation algorithm to perform the second step on the fat signal. The inhibition method can effectively improve the stability of fat signal inhibition (fat suppression), thereby improving the contrast between arteries and veins, as well as blood vessels and other background tissues, so as to achieve the purpose of enhancing the diagnostic value of vascular imaging.

Further, as a refinement and expansion of the specific implementation of the above-mentioned embodiment, in order to fully describe the specific implementation process of this embodiment, another magnetic resonance non-enhanced blood vessel imaging method is provided, as shown in FIG. 2 , the method includes:

Step 201 , using the non-selective water excitation pulse in the modified T2 magnetization preparation module to apply a first combined pulse to the area to be imaged to obtain a first water signal and a first fat signal.

In order to illustrate the specific implementation of step 201, as a preferred embodiment, step 201 may specifically include: based on the preset interval time in the first combined pulse, by controlling the excitation of water protons to the xy plane to obtain the first water signal, and by controlling the retention of fat protons 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.

In practice, the first combined pulse includes two 45° excitation pulses separated by a time τ. As shown in Fig. 3a, a first 45° excitation pulse is applied to the area to be imaged, and both water and fat protons in the area to be imaged are excited to the xy plane, deflected by 45°, and keep precessing in the deflected direction state, among which, precession refers to the situation in which atoms are subjected to the action of electromagnetic force, and their rotation axes rotate around a certain center except for spin, that is, the rotation axes of water protons and fat protons rotate around the z-axis. After the interval time τ, the precession phase difference between the water protons and the fat protons is an odd multiple of π. At this time, a second 45° excitation pulse is applied to the area 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 in the same state. Among them, τ is the time required for the precession phase difference between water protons and fat protons to reach an odd multiple of π. It is experimentally measured that the time required for the precession phase difference π is about 2.3ms under the condition of a magnetic field strength of 1.5T. , about 1.15ms under the condition of a magnetic field strength of 3.0T.

Step 202 , after waiting for a preset ratio of effective echo time, obtain the T2 relaxation distribution state of the first water signal, and the first fat signal remains unchanged.

In implementation, in the process of waiting for a preset ratio of effective echo time (TE _effective ), for example, the preset ratio is 1/2, as shown in FIG. 3b, the venous signal, the arterial signal and the muscle signal in the first water signal are respectively After T2 relaxation and the dispersion caused by the non-uniform static magnetic field, the transverse magnetization vectors of the venous signal, the arterial signal and the muscle signal decrease along their respective relaxation curves, the transverse magnetization vector of the arterial signal decreases slowly, and the transverse magnetization The larger the vector value is, the faster the transverse magnetization vector of the vein signal and the muscle signal (short T2 tissue) decreases, the smaller the transverse magnetization vector, and 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, waiting for TE _effective /2, to 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.

Step 203 , applying an inversion pulse to the area to be imaged by using the selective inversion recovery pulse in the modified T2 magnetization preparation module to obtain an inversion water signal and an inversion fat signal.

In the implementation, the selective inversion recovery pulse in the T2 magnetization preparation module is modified to be a single refocusing pulse, that is, a single 180° inversion pulse as an example, as shown in Figure 3a, a single 180° inversion pulse is applied to the area to be imaged. , excite the water protons to the reverse direction of the xy plane, and the fat protons are reversed from the positive z-axis direction to the negative z-axis direction, that is, the reversed water signal and the reversed fat signal are obtained.

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

In implementation, as shown in Fig. 3b, in the process of waiting for TE _effective /2, based on the distribution state of the magnetization vector 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, and the arterial signal continues to undergo T2 relaxation. , the magnetization vector difference between the venous signal and the muscle signal continues to increase, the venous signal and the muscle signal are further suppressed, and the water proton dispersion caused by the uneven static magnetic field completes the reunion. At this time, the fat signal is negative from the z-axis. The direction to the positive z-axis undergoes T1 relaxation, the magnetization vector of the fat signal gradually decreases, and the fat signal is suppressed, that is, waiting for TE _effective /2, and the distribution state of the different transverse magnetization vectors of the reversed water signal during this period is obtained, and the reversed fat The distribution state of the longitudinal magnetization vector of the signal.

Step 205, applying the second combined pulse to the area to be imaged by using the non-selective water excitation pulse in the modified T2 magnetization preparation module to obtain the second water signal and the second fat signal, wherein the second water signal is obtained by separation Water signals for different transverse magnetization vectors.

In order to illustrate the specific implementation of step 205, as a preferred embodiment, step 205 specifically further includes: applying a combined pulse to the area to be imaged based on the non-selective water excitation pulse in the modified T2 magnetization preparation module to control the transverse magnetization of the fat signal The vector is zero.

In order to illustrate the specific implementation of step 205, as a preferred embodiment, step 205 may specifically include: based on the preset interval time in the second combined pulse, by controlling the excitation of water protons from the xy plane to the positive direction of the z axis , the second water signal is obtained, and the second fat signal is obtained by controlling the retention of fat protons in the negative z-axis direction.

In implementation, the second combined pulse is the same as the first combined pulse. As shown in Figure 3a, the first 45° excitation pulse is applied to the area to be imaged again, 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 the precession state in the deflected direction. After the interval time τ is maintained, the precession phase difference between the water protons and the fat protons is an odd multiple of π. At this time, The second 45° excitation pulse is applied to the area to be imaged again, the water protons are excited to the positive z-axis direction, and the fat protons are excited to the negative z-axis direction, and within the second combined pulse time, the longitudinal magnetization vector of the fat signal continues to decrease . Based on the distribution of magnetization vectors of the reversed water signal and the reversed fat signal, a second water signal with different transverse magnetization vectors in the positive z-axis direction, and a second fat remaining in the negative z-axis direction with the magnetization vector approaching zero are obtained Signal.

As a preferred embodiment, the first combination pulse type includes 1-1 type combination pulse, 1-2-1 type combination pulse and 1-3-3-1 type combination pulse, the first combination pulse type and The second combined pulse type is the same, and the selective inversion recovery pulse in the modified T2 magnetization preparation module is a single polypulse, a double polypulse or a quadruple polypulse. When the modified T2 magnetization preparation module When the selective inversion recovery pulse is a double-convergence pulse or a quadruple-convergence pulse, the flip angle of the first pulse and the flip angle of the last pulse in the second combined pulse are in a complementary angle relationship.

Specifically, the combined pulse sequence of the double polypulse 1-1 type may be: 45 _x -45 _x -180 _y -180 _-y -45 _x -135 _-x ; the combined pulse sequence of the double polypulse 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 when the pulse is emitted, that is, the radio frequency phase, the single refocusing pulse can be It is an adiabatic pulse, which is not specifically limited here.

In practical application scenarios, based on the high fat reduction stability of this embodiment, it can be considered that at the expense of reducing the arterial signal-to-noise ratio, by extending the effective echo time TE _effective , the arterial and venous signals in the area to be imaged can be improved. , and the difference of the transverse magnetization vector between the blood vessel signal and the muscle signal, and prolonging the longitudinal relaxation time of the fat signal to reduce the longitudinal magnetization vector of the fat signal, so as to improve the relationship between the arteries and the arteries in the area to be imaged in the subsequent imaging process. Contrast of veins, and contrast between blood vessels and background tissue (e.g. fat, muscle).

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

In the implementation, after the correction T2 magnetization preparation module ends and waits for the preset interval time d, the longitudinal vector of the fat signal reaches zero, and at this time, the gradient echo sequence containing multiple pulses of the same flip angle is used for signal acquisition, and multiple echoes are obtained. The water signal corresponding to the time point. In the process of waiting for the preset interval time d, the blood signal, the muscle signal and the fat signal undergo T1 relaxation, wherein the preset interval time d is the time required for the longitudinal magnetization vector of the fat signal to approach the zero point.

Step 207: Obtain a non-enhanced blood vessel image including at least arterial features and vein features according to the water signals corresponding to the multiple echo time points.

In order to illustrate the specific implementation of step 207, as a preferred embodiment, the water signal also includes a muscle signal, and step 207 may specifically include: adjusting the effective echo time in the correction T2 magnetization preparation module to delay the effective echo time , using the two-point water-fat separation algorithm, by suppressing the fat signal and muscle signal in the area to be imaged, a non-enhanced blood vessel image that separates arterial and venous features is obtained.

In the implementation, according to the amplitude and phase map of the collected water signal, the two-point water-fat separation algorithm is used to separate the water image corresponding to the water signal, and the water image is used as the non-enhanced blood vessel image of the area to be imaged. Based on the results of the modified T2 magnetization preparation module for the first fat signal suppression, the two-point water-fat separation algorithm is used to suppress the fat signal twice. It can be seen that the stability of fat signal suppression can be effectively improved by suppressing the fat signal twice. Based on the stable fat signal suppression state, the extended effective echo time obtained after adjustment can further suppress the venous signal and muscle signal in the area to be imaged, thereby improving the contrast between arteries and veins, as well as arterial and vein and background tissues ( For example, the contrast ratio of muscles) makes this embodiment suitable for imaging of blood vessels in a wide range of the whole body, including parts such as neck, chest, abdomen, pelvis, limbs, etc., but not limited to the above parts.

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, and the longitudinal magnetization vector of the fat signal is controlled to be opposite to the direction of the main magnetic field, and the longitudinal magnetization vector of the water signal is controlled The direction is the same as that of the main magnetic field, and arterial signals and venous signals with different transverse magnetization vectors are obtained, and when the longitudinal vector of the fat signal reaches zero, the three-dimensional fast gradient echo sequence is used for signal acquisition, and multiple echo time points corresponding to According to the collected water signals corresponding to multiple echo time points, a two-point water-fat separation algorithm is used to obtain a non-enhanced blood vessel image containing at least arterial features and vein features. 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 the fat signal suppression (fat suppression) can be effectively improved It can improve the contrast between arteries and veins, as well as blood vessels and other background tissues, and achieve the purpose of enhancing the diagnostic value of vascular imaging.

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

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, 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 direction of the water signal. Similar to the main magnetic field, water signals with different transverse magnetization vectors are obtained, including arterial and venous signals.

The sequence acquisition module 42 can be configured to use a three-dimensional fast gradient echo sequence to perform signal acquisition when the longitudinal vector of the fat signal reaches zero to obtain water signals corresponding to multiple echo time points.

The reconstruction imaging module 43 can be used to obtain a non-enhanced blood vessel image including at least arterial features and vein features according to the water signals corresponding to multiple echo time points.

In a specific application scenario, as shown in FIG. 5 , 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 to control the transverse magnetization of the fat signal The vector is zero.

In a specific application scenario, as shown in FIG. 5 , 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 .

The first combined pulse unit 411 can be used to apply the first combined pulse to the area to be imaged by using the non-selective water excitation pulse in the modified T2 magnetization preparation module to obtain the first water signal and the first fat signal.

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

The inversion pulse unit 413 can be used to apply an inversion pulse to the area to be imaged by using the selective inversion recovery pulse in the modified T2 magnetization preparation module to obtain an inversion water signal and an inversion fat signal.

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

The second combined pulse unit 415 can be used to apply a second combined pulse to the area 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, the second water signal The signal is the water signal of different transverse magnetization vectors obtained by separation

In a specific application scenario, the first combined pulse type includes 1-1 type combined pulse, 1-2-1 type combined pulse and 1-3-3-1 type combined pulse, the first combined pulse type and The second combined pulse type is the same; the selective inversion recovery pulse in the modified T2 magnetization preparation module is a single polypulse, a double polypulse or a quadruple polypulse, when the modified T2 magnetization preparation module When the selective inversion recovery pulse is a double-convergence pulse or a quadruple-convergence pulse, the flip angle of the first pulse and the flip angle of the last pulse in the second combined pulse are in a complementary angle relationship.

In a specific application scenario, the water signal also includes muscle signals, and the reconstruction imaging module 43 can be specifically used to adjust the effective echo time in the correction T2 magnetization preparation module to delay the effective echo time, using the two-point method of water The fat separation algorithm obtains a non-enhanced blood vessel image that separates arterial and venous features by suppressing fat and muscle signals in the area to be imaged.

It should be noted that, for other corresponding descriptions of the functional units involved in the magnetic resonance non-enhanced vascular imaging device provided in the embodiments of the present application, reference may be made to the corresponding descriptions in FIG. 1 and FIG. 2 , which will not be repeated here.

Based on the above methods shown in FIGS. 1 and 2 , correspondingly, an embodiment of the present application further provides a storage medium on which a computer program is stored. Magnetic resonance non-enhanced angiography method shown.

Based on this 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, U disk, mobile hard disk, etc.), and includes several instructions to make A computer device (which may be a personal computer, a server, or a network device, etc.) executes the methods described in various implementation scenarios of this application.

Based on the methods shown in FIG. 1 and FIG. 2 and the virtual device embodiments shown in FIG. 4 and FIG. 5 , in order to achieve the above purpose, the embodiment of the present application also provides a computer device, which may be a personal computer, A server, a network device, etc., the physical 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 realize the above-mentioned non-enhanced magnetic resonance blood vessels shown in FIG. 1 and FIG. 2 . imaging method.

Optionally, the computer device may further include a user interface, a network interface, a camera, a radio frequency (Radio Frequency, RF) circuit, a sensor, an audio circuit, a WI-FI module, and the like. The user interface may include a display screen (Display), an input unit such as a keyboard (Keyboard), etc., and the optional user interface may also include a USB interface, a card reader interface, and the like. Optional network interfaces may include standard wired interfaces, wireless interfaces (such as Bluetooth interfaces, WI-FI interfaces), and the like.

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 physical device, and may include more or less components, or combine some components, or arrange different components.

The storage medium may also include an operating system and a network communication module. An operating system is a program that manages 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 realize the communication between various components inside the storage medium, as well as the communication with other hardware and software in the physical device.

From the description of the above embodiments, those skilled in the art can clearly understand that the present application can be implemented by means of software plus a necessary general hardware platform, and can also be implemented by hardware. By applying the technical solution of the present application, compared with the existing relaxation-based NCE-MRA technical solution, the present embodiment uses the non-selective water excitation pulse in the modified T2 magnetization preparation module to suppress the fat signal once, and then use the non-selective water excitation pulse in the modified T2 magnetization preparation module to suppress the fat signal. The method of secondary inhibition of fat signal after reaching the water signal can effectively improve the stability of fat signal inhibition (fat suppression), and improve the contrast between arteries and veins, as well as blood vessels and other background tissues, so as to enhance the diagnostic value of vascular imaging. Purpose.

Those skilled in the art can understand that the accompanying drawing is only a schematic diagram of a preferred implementation scenario, and the modules or processes in the accompanying drawing are not necessarily necessary to implement the present application. Those skilled in the art can understand that the modules in the device in the implementation scenario may be distributed in the device in the implementation scenario according to the description of the implementation scenario, or may be located in one or more devices different from the implementation scenario with corresponding changes. The modules of the above implementation scenarios may be combined into one module, or may be further split into multiple sub-modules.

The above serial numbers in the present application are only for description, and do not represent the pros and cons of the implementation scenarios. The above disclosures are only a few specific implementation scenarios of the present application, however, the present application is not limited thereto, and any changes that can be conceived by those skilled in the art should fall within the protection scope of the present application.

Claims (10)

1. A magnetic resonance non-enhanced blood vessel imaging method is characterized by specifically comprising the following steps:

applying a combined pulse to a region to be imaged based on a non-selective water excitation pulse in a corrected T2 magnetization preparation module, controlling the longitudinal magnetization vector of a fat signal to be opposite to the direction of a main magnetic field, and controlling the longitudinal magnetization vector of a water signal to be the same as the direction of the main magnetic field to obtain water signals with different transverse magnetization vectors, wherein the water signals comprise arterial signals and venous signals;

when the longitudinal vector of the fat signal reaches zero, performing signal acquisition by using a three-dimensional fast gradient echo sequence to obtain water signals corresponding to a plurality of echo time points;

and obtaining a non-enhanced blood vessel image at least comprising artery characteristics and vein characteristics according to the water signals corresponding to the multiple echo time points.

2. The method of claim 1, further comprising: the 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, and the transverse magnetization vector of the fat signal is controlled to be zero.

3. The method according to claim 1, wherein the applying of the combined pulse to the region 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 main magnetic field direction, and the longitudinal magnetization vector of the water signal to be the same as the main magnetic field direction, and obtains water signals with different transverse magnetization vectors, specifically comprising:

applying a first combined pulse to a region to be imaged by using a non-selective water excitation pulse in a corrected T2 magnetization preparation module to obtain a first water signal and a first fat signal;

applying inversion pulses to a region to be imaged by using selective inversion recovery pulses in a corrected T2 magnetization preparation module to obtain inversion water signals and inversion fat signals;

applying a second combined pulse to a region to be imaged by using a non-selective water excitation pulse in a corrected T2 magnetization preparation module to obtain a second water signal and a second fat signal;

and the second water signal is the water signals of different transverse magnetization vectors obtained by separation.

4. The method according to claim 3, wherein the applying the first 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 the first water signal and the first fat signal comprises:

based on preset interval time in the first combined pulse, a first water signal is obtained by controlling the excitation of water protons to an xy plane, and a first fat signal is obtained by controlling the retention of fat protons on a z axis;

wherein the precession phase difference of the water proton and the fat proton after the interval of time is an odd multiple of pi.

5. The method according to claim 4, wherein the step of obtaining the first water signal and the first fat signal by applying the first combined pulse to the region to be imaged by using the non-selective water excitation pulse in the modified T2 magnetization preparation module further comprises:

after waiting for the effective echo time with a preset proportion, obtaining a T2 relaxation distribution state of the first water signal, wherein the first fat signal is kept unchanged;

after the step of applying the inversion pulse to the region to be imaged by using the selective inversion recovery pulse in the correction T2 magnetization preparation module to obtain the inverted water signal and the inverted fat signal, the method specifically includes:

and after waiting for the effective echo time with a preset proportion, obtaining the T2 relaxation distribution state of the reversed water signal and the T1 relaxation distribution state of the reversed fat signal from the negative direction of the z axis to the positive direction of the z axis.

6. The method according to claim 3, wherein 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 comprises:

and based on the preset interval time in the second combined pulse, obtaining a second water signal by controlling the excitation of water protons from the xy plane to the positive direction of the z axis, and obtaining a second fat signal by controlling the retention of fat protons in the negative direction of the z axis.

7. The method of claim 3, wherein the first combined pulse type comprises a type 1-1 combined pulse, a type 1-2-1 combined pulse, and a type 1-3-3-1 combined pulse, and wherein the first combined pulse type and the second combined pulse type are the same;

the selective inversion recovery pulse in the corrected T2 magnetization preparation module is a monoplex pulse, a doublet pulse or a tetramer pulse, and when the selective inversion recovery pulse in the corrected T2 magnetization preparation module is a doublet pulse or a tetramer pulse, the flip angle of the first pulse and the flip angle of the last pulse in the second combined pulse are in a complementary angle relationship.

8. The method according to claim 1, wherein the water signals further include muscle signals, and the obtaining of the non-enhanced vessel image including at least the artery feature and the vein feature according to the water signals corresponding to the plurality of echo time points includes:

and adjusting the effective echo time in the corrected T2 magnetization preparation module to delay the effective echo time, and obtaining a non-enhanced blood vessel image for separating arterial features and venous features by inhibiting fat signals and muscle signals in a region to be imaged by using a two-point water-fat separation algorithm.

9. A magnetic resonance non-enhanced vascular imaging device is characterized by specifically comprising:

the magnetization preparation module is used for applying a combined pulse to a 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 a main magnetic field, and controlling 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, wherein the water signals comprise arterial signals and venous signals;

the sequence acquisition module is used for acquiring signals by utilizing a three-dimensional fast gradient echo sequence when the longitudinal vector of the fat signal reaches zero to obtain water signals corresponding to a plurality of echo time points;

and the reconstruction imaging module is used for obtaining a non-enhanced blood vessel image at least containing artery characteristics and vein characteristics according to the water signals corresponding to the multiple echo time points.

10. 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 the processor implements the magnetic resonance non-enhanced vessel imaging method according to any one of claims 1 to 8 when executing the program.

Images